feat(application): inital commit

vendor/golang.org/x/tools/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

vendor/golang.org/x/tools/PATENTS

@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.

vendor/golang.org/x/tools/go/gcexportdata/gcexportdata.go

@@ -0,0 +1,181 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package gcexportdata provides functions for locating, reading, and
+// writing export data files containing type information produced by the
+// gc compiler.  This package supports go1.7 export data format and all
+// later versions.
+//
+// Although it might seem convenient for this package to live alongside
+// go/types in the standard library, this would cause version skew
+// problems for developer tools that use it, since they must be able to
+// consume the outputs of the gc compiler both before and after a Go
+// update such as from Go 1.7 to Go 1.8.  Because this package lives in
+// golang.org/x/tools, sites can update their version of this repo some
+// time before the Go 1.8 release and rebuild and redeploy their
+// developer tools, which will then be able to consume both Go 1.7 and
+// Go 1.8 export data files, so they will work before and after the
+// Go update. (See discussion at https://golang.org/issue/15651.)
+package gcexportdata // import "golang.org/x/tools/go/gcexportdata"
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"go/token"
+	"go/types"
+	"io"
+	"io/ioutil"
+	"os/exec"
+
+	"golang.org/x/tools/internal/gcimporter"
+)
+
+// Find returns the name of an object (.o) or archive (.a) file
+// containing type information for the specified import path,
+// using the go command.
+// If no file was found, an empty filename is returned.
+//
+// A relative srcDir is interpreted relative to the current working directory.
+//
+// Find also returns the package's resolved (canonical) import path,
+// reflecting the effects of srcDir and vendoring on importPath.
+//
+// Deprecated: Use the higher-level API in golang.org/x/tools/go/packages,
+// which is more efficient.
+func Find(importPath, srcDir string) (filename, path string) {
+	cmd := exec.Command("go", "list", "-json", "-export", "--", importPath)
+	cmd.Dir = srcDir
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return "", ""
+	}
+	var data struct {
+		ImportPath string
+		Export     string
+	}
+	json.Unmarshal(out, &data)
+	return data.Export, data.ImportPath
+}
+
+// NewReader returns a reader for the export data section of an object
+// (.o) or archive (.a) file read from r.  The new reader may provide
+// additional trailing data beyond the end of the export data.
+func NewReader(r io.Reader) (io.Reader, error) {
+	buf := bufio.NewReader(r)
+	_, size, err := gcimporter.FindExportData(buf)
+	if err != nil {
+		return nil, err
+	}
+
+	if size >= 0 {
+		// We were given an archive and found the __.PKGDEF in it.
+		// This tells us the size of the export data, and we don't
+		// need to return the entire file.
+		return &io.LimitedReader{
+			R: buf,
+			N: size,
+		}, nil
+	} else {
+		// We were given an object file. As such, we don't know how large
+		// the export data is and must return the entire file.
+		return buf, nil
+	}
+}
+
+// Read reads export data from in, decodes it, and returns type
+// information for the package.
+//
+// The package path (effectively its linker symbol prefix) is
+// specified by path, since unlike the package name, this information
+// may not be recorded in the export data.
+//
+// File position information is added to fset.
+//
+// Read may inspect and add to the imports map to ensure that references
+// within the export data to other packages are consistent.  The caller
+// must ensure that imports[path] does not exist, or exists but is
+// incomplete (see types.Package.Complete), and Read inserts the
+// resulting package into this map entry.
+//
+// On return, the state of the reader is undefined.
+func Read(in io.Reader, fset *token.FileSet, imports map[string]*types.Package, path string) (*types.Package, error) {
+	data, err := ioutil.ReadAll(in)
+	if err != nil {
+		return nil, fmt.Errorf("reading export data for %q: %v", path, err)
+	}
+
+	if bytes.HasPrefix(data, []byte("!<arch>")) {
+		return nil, fmt.Errorf("can't read export data for %q directly from an archive file (call gcexportdata.NewReader first to extract export data)", path)
+	}
+
+	// The App Engine Go runtime v1.6 uses the old export data format.
+	// TODO(adonovan): delete once v1.7 has been around for a while.
+	if bytes.HasPrefix(data, []byte("package ")) {
+		return gcimporter.ImportData(imports, path, path, bytes.NewReader(data))
+	}
+
+	// The indexed export format starts with an 'i'; the older
+	// binary export format starts with a 'c', 'd', or 'v'
+	// (from "version"). Select appropriate importer.
+	if len(data) > 0 {
+		switch data[0] {
+		case 'i':
+			_, pkg, err := gcimporter.IImportData(fset, imports, data[1:], path)
+			return pkg, err
+
+		case 'v', 'c', 'd':
+			_, pkg, err := gcimporter.BImportData(fset, imports, data, path)
+			return pkg, err
+
+		case 'u':
+			_, pkg, err := gcimporter.UImportData(fset, imports, data[1:], path)
+			return pkg, err
+
+		default:
+			l := len(data)
+			if l > 10 {
+				l = 10
+			}
+			return nil, fmt.Errorf("unexpected export data with prefix %q for path %s", string(data[:l]), path)
+		}
+	}
+	return nil, fmt.Errorf("empty export data for %s", path)
+}
+
+// Write writes encoded type information for the specified package to out.
+// The FileSet provides file position information for named objects.
+func Write(out io.Writer, fset *token.FileSet, pkg *types.Package) error {
+	if _, err := io.WriteString(out, "i"); err != nil {
+		return err
+	}
+	return gcimporter.IExportData(out, fset, pkg)
+}
+
+// ReadBundle reads an export bundle from in, decodes it, and returns type
+// information for the packages.
+// File position information is added to fset.
+//
+// ReadBundle may inspect and add to the imports map to ensure that references
+// within the export bundle to other packages are consistent.
+//
+// On return, the state of the reader is undefined.
+//
+// Experimental: This API is experimental and may change in the future.
+func ReadBundle(in io.Reader, fset *token.FileSet, imports map[string]*types.Package) ([]*types.Package, error) {
+	data, err := ioutil.ReadAll(in)
+	if err != nil {
+		return nil, fmt.Errorf("reading export bundle: %v", err)
+	}
+	return gcimporter.IImportBundle(fset, imports, data)
+}
+
+// WriteBundle writes encoded type information for the specified packages to out.
+// The FileSet provides file position information for named objects.
+//
+// Experimental: This API is experimental and may change in the future.
+func WriteBundle(out io.Writer, fset *token.FileSet, pkgs []*types.Package) error {
+	return gcimporter.IExportBundle(out, fset, pkgs)
+}

vendor/golang.org/x/tools/go/gcexportdata/importer.go

@@ -0,0 +1,75 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gcexportdata
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+	"os"
+)
+
+// NewImporter returns a new instance of the types.Importer interface
+// that reads type information from export data files written by gc.
+// The Importer also satisfies types.ImporterFrom.
+//
+// Export data files are located using "go build" workspace conventions
+// and the build.Default context.
+//
+// Use this importer instead of go/importer.For("gc", ...) to avoid the
+// version-skew problems described in the documentation of this package,
+// or to control the FileSet or access the imports map populated during
+// package loading.
+//
+// Deprecated: Use the higher-level API in golang.org/x/tools/go/packages,
+// which is more efficient.
+func NewImporter(fset *token.FileSet, imports map[string]*types.Package) types.ImporterFrom {
+	return importer{fset, imports}
+}
+
+type importer struct {
+	fset    *token.FileSet
+	imports map[string]*types.Package
+}
+
+func (imp importer) Import(importPath string) (*types.Package, error) {
+	return imp.ImportFrom(importPath, "", 0)
+}
+
+func (imp importer) ImportFrom(importPath, srcDir string, mode types.ImportMode) (_ *types.Package, err error) {
+	filename, path := Find(importPath, srcDir)
+	if filename == "" {
+		if importPath == "unsafe" {
+			// Even for unsafe, call Find first in case
+			// the package was vendored.
+			return types.Unsafe, nil
+		}
+		return nil, fmt.Errorf("can't find import: %s", importPath)
+	}
+
+	if pkg, ok := imp.imports[path]; ok && pkg.Complete() {
+		return pkg, nil // cache hit
+	}
+
+	// open file
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		f.Close()
+		if err != nil {
+			// add file name to error
+			err = fmt.Errorf("reading export data: %s: %v", filename, err)
+		}
+	}()
+
+	r, err := NewReader(f)
+	if err != nil {
+		return nil, err
+	}
+
+	return Read(r, imp.fset, imp.imports, path)
+}

vendor/golang.org/x/tools/go/internal/packagesdriver/sizes.go

@@ -0,0 +1,49 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package packagesdriver fetches type sizes for go/packages and go/analysis.
+package packagesdriver
+
+import (
+	"context"
+	"fmt"
+	"go/types"
+	"strings"
+
+	"golang.org/x/tools/internal/gocommand"
+)
+
+var debug = false
+
+func GetSizesGolist(ctx context.Context, inv gocommand.Invocation, gocmdRunner *gocommand.Runner) (types.Sizes, error) {
+	inv.Verb = "list"
+	inv.Args = []string{"-f", "{{context.GOARCH}} {{context.Compiler}}", "--", "unsafe"}
+	stdout, stderr, friendlyErr, rawErr := gocmdRunner.RunRaw(ctx, inv)
+	var goarch, compiler string
+	if rawErr != nil {
+		if rawErrMsg := rawErr.Error(); strings.Contains(rawErrMsg, "cannot find main module") || strings.Contains(rawErrMsg, "go.mod file not found") {
+			// User's running outside of a module. All bets are off. Get GOARCH and guess compiler is gc.
+			// TODO(matloob): Is this a problem in practice?
+			inv.Verb = "env"
+			inv.Args = []string{"GOARCH"}
+			envout, enverr := gocmdRunner.Run(ctx, inv)
+			if enverr != nil {
+				return nil, enverr
+			}
+			goarch = strings.TrimSpace(envout.String())
+			compiler = "gc"
+		} else {
+			return nil, friendlyErr
+		}
+	} else {
+		fields := strings.Fields(stdout.String())
+		if len(fields) < 2 {
+			return nil, fmt.Errorf("could not parse GOARCH and Go compiler in format \"<GOARCH> <compiler>\":\nstdout: <<%s>>\nstderr: <<%s>>",
+				stdout.String(), stderr.String())
+		}
+		goarch = fields[0]
+		compiler = fields[1]
+	}
+	return types.SizesFor(compiler, goarch), nil
+}

vendor/golang.org/x/tools/go/packages/doc.go

@@ -0,0 +1,220 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package packages loads Go packages for inspection and analysis.
+
+The Load function takes as input a list of patterns and return a list of Package
+structs describing individual packages matched by those patterns.
+The LoadMode controls the amount of detail in the loaded packages.
+
+Load passes most patterns directly to the underlying build tool,
+but all patterns with the prefix "query=", where query is a
+non-empty string of letters from [a-z], are reserved and may be
+interpreted as query operators.
+
+Two query operators are currently supported: "file" and "pattern".
+
+The query "file=path/to/file.go" matches the package or packages enclosing
+the Go source file path/to/file.go.  For example "file=~/go/src/fmt/print.go"
+might return the packages "fmt" and "fmt [fmt.test]".
+
+The query "pattern=string" causes "string" to be passed directly to
+the underlying build tool. In most cases this is unnecessary,
+but an application can use Load("pattern=" + x) as an escaping mechanism
+to ensure that x is not interpreted as a query operator if it contains '='.
+
+All other query operators are reserved for future use and currently
+cause Load to report an error.
+
+The Package struct provides basic information about the package, including
+
+  - ID, a unique identifier for the package in the returned set;
+  - GoFiles, the names of the package's Go source files;
+  - Imports, a map from source import strings to the Packages they name;
+  - Types, the type information for the package's exported symbols;
+  - Syntax, the parsed syntax trees for the package's source code; and
+  - TypeInfo, the result of a complete type-check of the package syntax trees.
+
+(See the documentation for type Package for the complete list of fields
+and more detailed descriptions.)
+
+For example,
+
+	Load(nil, "bytes", "unicode...")
+
+returns four Package structs describing the standard library packages
+bytes, unicode, unicode/utf16, and unicode/utf8. Note that one pattern
+can match multiple packages and that a package might be matched by
+multiple patterns: in general it is not possible to determine which
+packages correspond to which patterns.
+
+Note that the list returned by Load contains only the packages matched
+by the patterns. Their dependencies can be found by walking the import
+graph using the Imports fields.
+
+The Load function can be configured by passing a pointer to a Config as
+the first argument. A nil Config is equivalent to the zero Config, which
+causes Load to run in LoadFiles mode, collecting minimal information.
+See the documentation for type Config for details.
+
+As noted earlier, the Config.Mode controls the amount of detail
+reported about the loaded packages. See the documentation for type LoadMode
+for details.
+
+Most tools should pass their command-line arguments (after any flags)
+uninterpreted to the loader, so that the loader can interpret them
+according to the conventions of the underlying build system.
+See the Example function for typical usage.
+*/
+package packages // import "golang.org/x/tools/go/packages"
+
+/*
+
+Motivation and design considerations
+
+The new package's design solves problems addressed by two existing
+packages: go/build, which locates and describes packages, and
+golang.org/x/tools/go/loader, which loads, parses and type-checks them.
+The go/build.Package structure encodes too much of the 'go build' way
+of organizing projects, leaving us in need of a data type that describes a
+package of Go source code independent of the underlying build system.
+We wanted something that works equally well with go build and vgo, and
+also other build systems such as Bazel and Blaze, making it possible to
+construct analysis tools that work in all these environments.
+Tools such as errcheck and staticcheck were essentially unavailable to
+the Go community at Google, and some of Google's internal tools for Go
+are unavailable externally.
+This new package provides a uniform way to obtain package metadata by
+querying each of these build systems, optionally supporting their
+preferred command-line notations for packages, so that tools integrate
+neatly with users' build environments. The Metadata query function
+executes an external query tool appropriate to the current workspace.
+
+Loading packages always returns the complete import graph "all the way down",
+even if all you want is information about a single package, because the query
+mechanisms of all the build systems we currently support ({go,vgo} list, and
+blaze/bazel aspect-based query) cannot provide detailed information
+about one package without visiting all its dependencies too, so there is
+no additional asymptotic cost to providing transitive information.
+(This property might not be true of a hypothetical 5th build system.)
+
+In calls to TypeCheck, all initial packages, and any package that
+transitively depends on one of them, must be loaded from source.
+Consider A->B->C->D->E: if A,C are initial, A,B,C must be loaded from
+source; D may be loaded from export data, and E may not be loaded at all
+(though it's possible that D's export data mentions it, so a
+types.Package may be created for it and exposed.)
+
+The old loader had a feature to suppress type-checking of function
+bodies on a per-package basis, primarily intended to reduce the work of
+obtaining type information for imported packages. Now that imports are
+satisfied by export data, the optimization no longer seems necessary.
+
+Despite some early attempts, the old loader did not exploit export data,
+instead always using the equivalent of WholeProgram mode. This was due
+to the complexity of mixing source and export data packages (now
+resolved by the upward traversal mentioned above), and because export data
+files were nearly always missing or stale. Now that 'go build' supports
+caching, all the underlying build systems can guarantee to produce
+export data in a reasonable (amortized) time.
+
+Test "main" packages synthesized by the build system are now reported as
+first-class packages, avoiding the need for clients (such as go/ssa) to
+reinvent this generation logic.
+
+One way in which go/packages is simpler than the old loader is in its
+treatment of in-package tests. In-package tests are packages that
+consist of all the files of the library under test, plus the test files.
+The old loader constructed in-package tests by a two-phase process of
+mutation called "augmentation": first it would construct and type check
+all the ordinary library packages and type-check the packages that
+depend on them; then it would add more (test) files to the package and
+type-check again. This two-phase approach had four major problems:
+1) in processing the tests, the loader modified the library package,
+   leaving no way for a client application to see both the test
+   package and the library package; one would mutate into the other.
+2) because test files can declare additional methods on types defined in
+   the library portion of the package, the dispatch of method calls in
+   the library portion was affected by the presence of the test files.
+   This should have been a clue that the packages were logically
+   different.
+3) this model of "augmentation" assumed at most one in-package test
+   per library package, which is true of projects using 'go build',
+   but not other build systems.
+4) because of the two-phase nature of test processing, all packages that
+   import the library package had to be processed before augmentation,
+   forcing a "one-shot" API and preventing the client from calling Load
+   in several times in sequence as is now possible in WholeProgram mode.
+   (TypeCheck mode has a similar one-shot restriction for a different reason.)
+
+Early drafts of this package supported "multi-shot" operation.
+Although it allowed clients to make a sequence of calls (or concurrent
+calls) to Load, building up the graph of Packages incrementally,
+it was of marginal value: it complicated the API
+(since it allowed some options to vary across calls but not others),
+it complicated the implementation,
+it cannot be made to work in Types mode, as explained above,
+and it was less efficient than making one combined call (when this is possible).
+Among the clients we have inspected, none made multiple calls to load
+but could not be easily and satisfactorily modified to make only a single call.
+However, applications changes may be required.
+For example, the ssadump command loads the user-specified packages
+and in addition the runtime package.  It is tempting to simply append
+"runtime" to the user-provided list, but that does not work if the user
+specified an ad-hoc package such as [a.go b.go].
+Instead, ssadump no longer requests the runtime package,
+but seeks it among the dependencies of the user-specified packages,
+and emits an error if it is not found.
+
+Overlays: The Overlay field in the Config allows providing alternate contents
+for Go source files, by providing a mapping from file path to contents.
+go/packages will pull in new imports added in overlay files when go/packages
+is run in LoadImports mode or greater.
+Overlay support for the go list driver isn't complete yet: if the file doesn't
+exist on disk, it will only be recognized in an overlay if it is a non-test file
+and the package would be reported even without the overlay.
+
+Questions & Tasks
+
+- Add GOARCH/GOOS?
+  They are not portable concepts, but could be made portable.
+  Our goal has been to allow users to express themselves using the conventions
+  of the underlying build system: if the build system honors GOARCH
+  during a build and during a metadata query, then so should
+  applications built atop that query mechanism.
+  Conversely, if the target architecture of the build is determined by
+  command-line flags, the application can pass the relevant
+  flags through to the build system using a command such as:
+    myapp -query_flag="--cpu=amd64" -query_flag="--os=darwin"
+  However, this approach is low-level, unwieldy, and non-portable.
+  GOOS and GOARCH seem important enough to warrant a dedicated option.
+
+- How should we handle partial failures such as a mixture of good and
+  malformed patterns, existing and non-existent packages, successful and
+  failed builds, import failures, import cycles, and so on, in a call to
+  Load?
+
+- Support bazel, blaze, and go1.10 list, not just go1.11 list.
+
+- Handle (and test) various partial success cases, e.g.
+  a mixture of good packages and:
+  invalid patterns
+  nonexistent packages
+  empty packages
+  packages with malformed package or import declarations
+  unreadable files
+  import cycles
+  other parse errors
+  type errors
+  Make sure we record errors at the correct place in the graph.
+
+- Missing packages among initial arguments are not reported.
+  Return bogus packages for them, like golist does.
+
+- "undeclared name" errors (for example) are reported out of source file
+  order. I suspect this is due to the breadth-first resolution now used
+  by go/types. Is that a bug? Discuss with gri.
+
+*/

vendor/golang.org/x/tools/go/packages/external.go

@@ -0,0 +1,101 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file enables an external tool to intercept package requests.
+// If the tool is present then its results are used in preference to
+// the go list command.
+
+package packages
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	exec "golang.org/x/sys/execabs"
+	"os"
+	"strings"
+)
+
+// The Driver Protocol
+//
+// The driver, given the inputs to a call to Load, returns metadata about the packages specified.
+// This allows for different build systems to support go/packages by telling go/packages how the
+// packages' source is organized.
+// The driver is a binary, either specified by the GOPACKAGESDRIVER environment variable or in
+// the path as gopackagesdriver. It's given the inputs to load in its argv. See the package
+// documentation in doc.go for the full description of the patterns that need to be supported.
+// A driver receives as a JSON-serialized driverRequest struct in standard input and will
+// produce a JSON-serialized driverResponse (see definition in packages.go) in its standard output.
+
+// driverRequest is used to provide the portion of Load's Config that is needed by a driver.
+type driverRequest struct {
+	Mode LoadMode `json:"mode"`
+	// Env specifies the environment the underlying build system should be run in.
+	Env []string `json:"env"`
+	// BuildFlags are flags that should be passed to the underlying build system.
+	BuildFlags []string `json:"build_flags"`
+	// Tests specifies whether the patterns should also return test packages.
+	Tests bool `json:"tests"`
+	// Overlay maps file paths (relative to the driver's working directory) to the byte contents
+	// of overlay files.
+	Overlay map[string][]byte `json:"overlay"`
+}
+
+// findExternalDriver returns the file path of a tool that supplies
+// the build system package structure, or "" if not found."
+// If GOPACKAGESDRIVER is set in the environment findExternalTool returns its
+// value, otherwise it searches for a binary named gopackagesdriver on the PATH.
+func findExternalDriver(cfg *Config) driver {
+	const toolPrefix = "GOPACKAGESDRIVER="
+	tool := ""
+	for _, env := range cfg.Env {
+		if val := strings.TrimPrefix(env, toolPrefix); val != env {
+			tool = val
+		}
+	}
+	if tool != "" && tool == "off" {
+		return nil
+	}
+	if tool == "" {
+		var err error
+		tool, err = exec.LookPath("gopackagesdriver")
+		if err != nil {
+			return nil
+		}
+	}
+	return func(cfg *Config, words ...string) (*driverResponse, error) {
+		req, err := json.Marshal(driverRequest{
+			Mode:       cfg.Mode,
+			Env:        cfg.Env,
+			BuildFlags: cfg.BuildFlags,
+			Tests:      cfg.Tests,
+			Overlay:    cfg.Overlay,
+		})
+		if err != nil {
+			return nil, fmt.Errorf("failed to encode message to driver tool: %v", err)
+		}
+
+		buf := new(bytes.Buffer)
+		stderr := new(bytes.Buffer)
+		cmd := exec.CommandContext(cfg.Context, tool, words...)
+		cmd.Dir = cfg.Dir
+		cmd.Env = cfg.Env
+		cmd.Stdin = bytes.NewReader(req)
+		cmd.Stdout = buf
+		cmd.Stderr = stderr
+
+		if err := cmd.Run(); err != nil {
+			return nil, fmt.Errorf("%v: %v: %s", tool, err, cmd.Stderr)
+		}
+		if len(stderr.Bytes()) != 0 && os.Getenv("GOPACKAGESPRINTDRIVERERRORS") != "" {
+			fmt.Fprintf(os.Stderr, "%s stderr: <<%s>>\n", cmdDebugStr(cmd), stderr)
+		}
+
+		var response driverResponse
+		if err := json.Unmarshal(buf.Bytes(), &response); err != nil {
+			return nil, err
+		}
+		return &response, nil
+	}
+}

vendor/golang.org/x/tools/go/packages/golist_overlay.go

@@ -0,0 +1,575 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packages
+
+import (
+	"encoding/json"
+	"fmt"
+	"go/parser"
+	"go/token"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/internal/gocommand"
+)
+
+// processGolistOverlay provides rudimentary support for adding
+// files that don't exist on disk to an overlay. The results can be
+// sometimes incorrect.
+// TODO(matloob): Handle unsupported cases, including the following:
+// - determining the correct package to add given a new import path
+func (state *golistState) processGolistOverlay(response *responseDeduper) (modifiedPkgs, needPkgs []string, err error) {
+	havePkgs := make(map[string]string) // importPath -> non-test package ID
+	needPkgsSet := make(map[string]bool)
+	modifiedPkgsSet := make(map[string]bool)
+
+	pkgOfDir := make(map[string][]*Package)
+	for _, pkg := range response.dr.Packages {
+		// This is an approximation of import path to id. This can be
+		// wrong for tests, vendored packages, and a number of other cases.
+		havePkgs[pkg.PkgPath] = pkg.ID
+		dir, err := commonDir(pkg.GoFiles)
+		if err != nil {
+			return nil, nil, err
+		}
+		if dir != "" {
+			pkgOfDir[dir] = append(pkgOfDir[dir], pkg)
+		}
+	}
+
+	// If no new imports are added, it is safe to avoid loading any needPkgs.
+	// Otherwise, it's hard to tell which package is actually being loaded
+	// (due to vendoring) and whether any modified package will show up
+	// in the transitive set of dependencies (because new imports are added,
+	// potentially modifying the transitive set of dependencies).
+	var overlayAddsImports bool
+
+	// If both a package and its test package are created by the overlay, we
+	// need the real package first. Process all non-test files before test
+	// files, and make the whole process deterministic while we're at it.
+	var overlayFiles []string
+	for opath := range state.cfg.Overlay {
+		overlayFiles = append(overlayFiles, opath)
+	}
+	sort.Slice(overlayFiles, func(i, j int) bool {
+		iTest := strings.HasSuffix(overlayFiles[i], "_test.go")
+		jTest := strings.HasSuffix(overlayFiles[j], "_test.go")
+		if iTest != jTest {
+			return !iTest // non-tests are before tests.
+		}
+		return overlayFiles[i] < overlayFiles[j]
+	})
+	for _, opath := range overlayFiles {
+		contents := state.cfg.Overlay[opath]
+		base := filepath.Base(opath)
+		dir := filepath.Dir(opath)
+		var pkg *Package           // if opath belongs to both a package and its test variant, this will be the test variant
+		var testVariantOf *Package // if opath is a test file, this is the package it is testing
+		var fileExists bool
+		isTestFile := strings.HasSuffix(opath, "_test.go")
+		pkgName, ok := extractPackageName(opath, contents)
+		if !ok {
+			// Don't bother adding a file that doesn't even have a parsable package statement
+			// to the overlay.
+			continue
+		}
+		// If all the overlay files belong to a different package, change the
+		// package name to that package.
+		maybeFixPackageName(pkgName, isTestFile, pkgOfDir[dir])
+	nextPackage:
+		for _, p := range response.dr.Packages {
+			if pkgName != p.Name && p.ID != "command-line-arguments" {
+				continue
+			}
+			for _, f := range p.GoFiles {
+				if !sameFile(filepath.Dir(f), dir) {
+					continue
+				}
+				// Make sure to capture information on the package's test variant, if needed.
+				if isTestFile && !hasTestFiles(p) {
+					// TODO(matloob): Are there packages other than the 'production' variant
+					// of a package that this can match? This shouldn't match the test main package
+					// because the file is generated in another directory.
+					testVariantOf = p
+					continue nextPackage
+				} else if !isTestFile && hasTestFiles(p) {
+					// We're examining a test variant, but the overlaid file is
+					// a non-test file. Because the overlay implementation
+					// (currently) only adds a file to one package, skip this
+					// package, so that we can add the file to the production
+					// variant of the package. (https://golang.org/issue/36857
+					// tracks handling overlays on both the production and test
+					// variant of a package).
+					continue nextPackage
+				}
+				if pkg != nil && p != pkg && pkg.PkgPath == p.PkgPath {
+					// We have already seen the production version of the
+					// for which p is a test variant.
+					if hasTestFiles(p) {
+						testVariantOf = pkg
+					}
+				}
+				pkg = p
+				if filepath.Base(f) == base {
+					fileExists = true
+				}
+			}
+		}
+		// The overlay could have included an entirely new package or an
+		// ad-hoc package. An ad-hoc package is one that we have manually
+		// constructed from inadequate `go list` results for a file= query.
+		// It will have the ID command-line-arguments.
+		if pkg == nil || pkg.ID == "command-line-arguments" {
+			// Try to find the module or gopath dir the file is contained in.
+			// Then for modules, add the module opath to the beginning.
+			pkgPath, ok, err := state.getPkgPath(dir)
+			if err != nil {
+				return nil, nil, err
+			}
+			if !ok {
+				break
+			}
+			var forTest string // only set for x tests
+			isXTest := strings.HasSuffix(pkgName, "_test")
+			if isXTest {
+				forTest = pkgPath
+				pkgPath += "_test"
+			}
+			id := pkgPath
+			if isTestFile {
+				if isXTest {
+					id = fmt.Sprintf("%s [%s.test]", pkgPath, forTest)
+				} else {
+					id = fmt.Sprintf("%s [%s.test]", pkgPath, pkgPath)
+				}
+			}
+			if pkg != nil {
+				// TODO(rstambler): We should change the package's path and ID
+				// here. The only issue is that this messes with the roots.
+			} else {
+				// Try to reclaim a package with the same ID, if it exists in the response.
+				for _, p := range response.dr.Packages {
+					if reclaimPackage(p, id, opath, contents) {
+						pkg = p
+						break
+					}
+				}
+				// Otherwise, create a new package.
+				if pkg == nil {
+					pkg = &Package{
+						PkgPath: pkgPath,
+						ID:      id,
+						Name:    pkgName,
+						Imports: make(map[string]*Package),
+					}
+					response.addPackage(pkg)
+					havePkgs[pkg.PkgPath] = id
+					// Add the production package's sources for a test variant.
+					if isTestFile && !isXTest && testVariantOf != nil {
+						pkg.GoFiles = append(pkg.GoFiles, testVariantOf.GoFiles...)
+						pkg.CompiledGoFiles = append(pkg.CompiledGoFiles, testVariantOf.CompiledGoFiles...)
+						// Add the package under test and its imports to the test variant.
+						pkg.forTest = testVariantOf.PkgPath
+						for k, v := range testVariantOf.Imports {
+							pkg.Imports[k] = &Package{ID: v.ID}
+						}
+					}
+					if isXTest {
+						pkg.forTest = forTest
+					}
+				}
+			}
+		}
+		if !fileExists {
+			pkg.GoFiles = append(pkg.GoFiles, opath)
+			// TODO(matloob): Adding the file to CompiledGoFiles can exhibit the wrong behavior
+			// if the file will be ignored due to its build tags.
+			pkg.CompiledGoFiles = append(pkg.CompiledGoFiles, opath)
+			modifiedPkgsSet[pkg.ID] = true
+		}
+		imports, err := extractImports(opath, contents)
+		if err != nil {
+			// Let the parser or type checker report errors later.
+			continue
+		}
+		for _, imp := range imports {
+			// TODO(rstambler): If the package is an x test and the import has
+			// a test variant, make sure to replace it.
+			if _, found := pkg.Imports[imp]; found {
+				continue
+			}
+			overlayAddsImports = true
+			id, ok := havePkgs[imp]
+			if !ok {
+				var err error
+				id, err = state.resolveImport(dir, imp)
+				if err != nil {
+					return nil, nil, err
+				}
+			}
+			pkg.Imports[imp] = &Package{ID: id}
+			// Add dependencies to the non-test variant version of this package as well.
+			if testVariantOf != nil {
+				testVariantOf.Imports[imp] = &Package{ID: id}
+			}
+		}
+	}
+
+	// toPkgPath guesses the package path given the id.
+	toPkgPath := func(sourceDir, id string) (string, error) {
+		if i := strings.IndexByte(id, ' '); i >= 0 {
+			return state.resolveImport(sourceDir, id[:i])
+		}
+		return state.resolveImport(sourceDir, id)
+	}
+
+	// Now that new packages have been created, do another pass to determine
+	// the new set of missing packages.
+	for _, pkg := range response.dr.Packages {
+		for _, imp := range pkg.Imports {
+			if len(pkg.GoFiles) == 0 {
+				return nil, nil, fmt.Errorf("cannot resolve imports for package %q with no Go files", pkg.PkgPath)
+			}
+			pkgPath, err := toPkgPath(filepath.Dir(pkg.GoFiles[0]), imp.ID)
+			if err != nil {
+				return nil, nil, err
+			}
+			if _, ok := havePkgs[pkgPath]; !ok {
+				needPkgsSet[pkgPath] = true
+			}
+		}
+	}
+
+	if overlayAddsImports {
+		needPkgs = make([]string, 0, len(needPkgsSet))
+		for pkg := range needPkgsSet {
+			needPkgs = append(needPkgs, pkg)
+		}
+	}
+	modifiedPkgs = make([]string, 0, len(modifiedPkgsSet))
+	for pkg := range modifiedPkgsSet {
+		modifiedPkgs = append(modifiedPkgs, pkg)
+	}
+	return modifiedPkgs, needPkgs, err
+}
+
+// resolveImport finds the ID of a package given its import path.
+// In particular, it will find the right vendored copy when in GOPATH mode.
+func (state *golistState) resolveImport(sourceDir, importPath string) (string, error) {
+	env, err := state.getEnv()
+	if err != nil {
+		return "", err
+	}
+	if env["GOMOD"] != "" {
+		return importPath, nil
+	}
+
+	searchDir := sourceDir
+	for {
+		vendorDir := filepath.Join(searchDir, "vendor")
+		exists, ok := state.vendorDirs[vendorDir]
+		if !ok {
+			info, err := os.Stat(vendorDir)
+			exists = err == nil && info.IsDir()
+			state.vendorDirs[vendorDir] = exists
+		}
+
+		if exists {
+			vendoredPath := filepath.Join(vendorDir, importPath)
+			if info, err := os.Stat(vendoredPath); err == nil && info.IsDir() {
+				// We should probably check for .go files here, but shame on anyone who fools us.
+				path, ok, err := state.getPkgPath(vendoredPath)
+				if err != nil {
+					return "", err
+				}
+				if ok {
+					return path, nil
+				}
+			}
+		}
+
+		// We know we've hit the top of the filesystem when we Dir / and get /,
+		// or C:\ and get C:\, etc.
+		next := filepath.Dir(searchDir)
+		if next == searchDir {
+			break
+		}
+		searchDir = next
+	}
+	return importPath, nil
+}
+
+func hasTestFiles(p *Package) bool {
+	for _, f := range p.GoFiles {
+		if strings.HasSuffix(f, "_test.go") {
+			return true
+		}
+	}
+	return false
+}
+
+// determineRootDirs returns a mapping from absolute directories that could
+// contain code to their corresponding import path prefixes.
+func (state *golistState) determineRootDirs() (map[string]string, error) {
+	env, err := state.getEnv()
+	if err != nil {
+		return nil, err
+	}
+	if env["GOMOD"] != "" {
+		state.rootsOnce.Do(func() {
+			state.rootDirs, state.rootDirsError = state.determineRootDirsModules()
+		})
+	} else {
+		state.rootsOnce.Do(func() {
+			state.rootDirs, state.rootDirsError = state.determineRootDirsGOPATH()
+		})
+	}
+	return state.rootDirs, state.rootDirsError
+}
+
+func (state *golistState) determineRootDirsModules() (map[string]string, error) {
+	// List all of the modules--the first will be the directory for the main
+	// module. Any replaced modules will also need to be treated as roots.
+	// Editing files in the module cache isn't a great idea, so we don't
+	// plan to ever support that.
+	out, err := state.invokeGo("list", "-m", "-json", "all")
+	if err != nil {
+		// 'go list all' will fail if we're outside of a module and
+		// GO111MODULE=on. Try falling back without 'all'.
+		var innerErr error
+		out, innerErr = state.invokeGo("list", "-m", "-json")
+		if innerErr != nil {
+			return nil, err
+		}
+	}
+	roots := map[string]string{}
+	modules := map[string]string{}
+	var i int
+	for dec := json.NewDecoder(out); dec.More(); {
+		mod := new(gocommand.ModuleJSON)
+		if err := dec.Decode(mod); err != nil {
+			return nil, err
+		}
+		if mod.Dir != "" && mod.Path != "" {
+			// This is a valid module; add it to the map.
+			absDir, err := filepath.Abs(mod.Dir)
+			if err != nil {
+				return nil, err
+			}
+			modules[absDir] = mod.Path
+			// The first result is the main module.
+			if i == 0 || mod.Replace != nil && mod.Replace.Path != "" {
+				roots[absDir] = mod.Path
+			}
+		}
+		i++
+	}
+	return roots, nil
+}
+
+func (state *golistState) determineRootDirsGOPATH() (map[string]string, error) {
+	m := map[string]string{}
+	for _, dir := range filepath.SplitList(state.mustGetEnv()["GOPATH"]) {
+		absDir, err := filepath.Abs(dir)
+		if err != nil {
+			return nil, err
+		}
+		m[filepath.Join(absDir, "src")] = ""
+	}
+	return m, nil
+}
+
+func extractImports(filename string, contents []byte) ([]string, error) {
+	f, err := parser.ParseFile(token.NewFileSet(), filename, contents, parser.ImportsOnly) // TODO(matloob): reuse fileset?
+	if err != nil {
+		return nil, err
+	}
+	var res []string
+	for _, imp := range f.Imports {
+		quotedPath := imp.Path.Value
+		path, err := strconv.Unquote(quotedPath)
+		if err != nil {
+			return nil, err
+		}
+		res = append(res, path)
+	}
+	return res, nil
+}
+
+// reclaimPackage attempts to reuse a package that failed to load in an overlay.
+//
+// If the package has errors and has no Name, GoFiles, or Imports,
+// then it's possible that it doesn't yet exist on disk.
+func reclaimPackage(pkg *Package, id string, filename string, contents []byte) bool {
+	// TODO(rstambler): Check the message of the actual error?
+	// It differs between $GOPATH and module mode.
+	if pkg.ID != id {
+		return false
+	}
+	if len(pkg.Errors) != 1 {
+		return false
+	}
+	if pkg.Name != "" || pkg.ExportFile != "" {
+		return false
+	}
+	if len(pkg.GoFiles) > 0 || len(pkg.CompiledGoFiles) > 0 || len(pkg.OtherFiles) > 0 {
+		return false
+	}
+	if len(pkg.Imports) > 0 {
+		return false
+	}
+	pkgName, ok := extractPackageName(filename, contents)
+	if !ok {
+		return false
+	}
+	pkg.Name = pkgName
+	pkg.Errors = nil
+	return true
+}
+
+func extractPackageName(filename string, contents []byte) (string, bool) {
+	// TODO(rstambler): Check the message of the actual error?
+	// It differs between $GOPATH and module mode.
+	f, err := parser.ParseFile(token.NewFileSet(), filename, contents, parser.PackageClauseOnly) // TODO(matloob): reuse fileset?
+	if err != nil {
+		return "", false
+	}
+	return f.Name.Name, true
+}
+
+// commonDir returns the directory that all files are in, "" if files is empty,
+// or an error if they aren't in the same directory.
+func commonDir(files []string) (string, error) {
+	seen := make(map[string]bool)
+	for _, f := range files {
+		seen[filepath.Dir(f)] = true
+	}
+	if len(seen) > 1 {
+		return "", fmt.Errorf("files (%v) are in more than one directory: %v", files, seen)
+	}
+	for k := range seen {
+		// seen has only one element; return it.
+		return k, nil
+	}
+	return "", nil // no files
+}
+
+// It is possible that the files in the disk directory dir have a different package
+// name from newName, which is deduced from the overlays. If they all have a different
+// package name, and they all have the same package name, then that name becomes
+// the package name.
+// It returns true if it changes the package name, false otherwise.
+func maybeFixPackageName(newName string, isTestFile bool, pkgsOfDir []*Package) {
+	names := make(map[string]int)
+	for _, p := range pkgsOfDir {
+		names[p.Name]++
+	}
+	if len(names) != 1 {
+		// some files are in different packages
+		return
+	}
+	var oldName string
+	for k := range names {
+		oldName = k
+	}
+	if newName == oldName {
+		return
+	}
+	// We might have a case where all of the package names in the directory are
+	// the same, but the overlay file is for an x test, which belongs to its
+	// own package. If the x test does not yet exist on disk, we may not yet
+	// have its package name on disk, but we should not rename the packages.
+	//
+	// We use a heuristic to determine if this file belongs to an x test:
+	// The test file should have a package name whose package name has a _test
+	// suffix or looks like "newName_test".
+	maybeXTest := strings.HasPrefix(oldName+"_test", newName) || strings.HasSuffix(newName, "_test")
+	if isTestFile && maybeXTest {
+		return
+	}
+	for _, p := range pkgsOfDir {
+		p.Name = newName
+	}
+}
+
+// This function is copy-pasted from
+// https://github.com/golang/go/blob/9706f510a5e2754595d716bd64be8375997311fb/src/cmd/go/internal/search/search.go#L360.
+// It should be deleted when we remove support for overlays from go/packages.
+//
+// NOTE: This does not handle any ./... or ./ style queries, as this function
+// doesn't know the working directory.
+//
+// matchPattern(pattern)(name) reports whether
+// name matches pattern. Pattern is a limited glob
+// pattern in which '...' means 'any string' and there
+// is no other special syntax.
+// Unfortunately, there are two special cases. Quoting "go help packages":
+//
+// First, /... at the end of the pattern can match an empty string,
+// so that net/... matches both net and packages in its subdirectories, like net/http.
+// Second, any slash-separated pattern element containing a wildcard never
+// participates in a match of the "vendor" element in the path of a vendored
+// package, so that ./... does not match packages in subdirectories of
+// ./vendor or ./mycode/vendor, but ./vendor/... and ./mycode/vendor/... do.
+// Note, however, that a directory named vendor that itself contains code
+// is not a vendored package: cmd/vendor would be a command named vendor,
+// and the pattern cmd/... matches it.
+func matchPattern(pattern string) func(name string) bool {
+	// Convert pattern to regular expression.
+	// The strategy for the trailing /... is to nest it in an explicit ? expression.
+	// The strategy for the vendor exclusion is to change the unmatchable
+	// vendor strings to a disallowed code point (vendorChar) and to use
+	// "(anything but that codepoint)*" as the implementation of the ... wildcard.
+	// This is a bit complicated but the obvious alternative,
+	// namely a hand-written search like in most shell glob matchers,
+	// is too easy to make accidentally exponential.
+	// Using package regexp guarantees linear-time matching.
+
+	const vendorChar = "\x00"
+
+	if strings.Contains(pattern, vendorChar) {
+		return func(name string) bool { return false }
+	}
+
+	re := regexp.QuoteMeta(pattern)
+	re = replaceVendor(re, vendorChar)
+	switch {
+	case strings.HasSuffix(re, `/`+vendorChar+`/\.\.\.`):
+		re = strings.TrimSuffix(re, `/`+vendorChar+`/\.\.\.`) + `(/vendor|/` + vendorChar + `/\.\.\.)`
+	case re == vendorChar+`/\.\.\.`:
+		re = `(/vendor|/` + vendorChar + `/\.\.\.)`
+	case strings.HasSuffix(re, `/\.\.\.`):
+		re = strings.TrimSuffix(re, `/\.\.\.`) + `(/\.\.\.)?`
+	}
+	re = strings.ReplaceAll(re, `\.\.\.`, `[^`+vendorChar+`]*`)
+
+	reg := regexp.MustCompile(`^` + re + `$`)
+
+	return func(name string) bool {
+		if strings.Contains(name, vendorChar) {
+			return false
+		}
+		return reg.MatchString(replaceVendor(name, vendorChar))
+	}
+}
+
+// replaceVendor returns the result of replacing
+// non-trailing vendor path elements in x with repl.
+func replaceVendor(x, repl string) string {
+	if !strings.Contains(x, "vendor") {
+		return x
+	}
+	elem := strings.Split(x, "/")
+	for i := 0; i < len(elem)-1; i++ {
+		if elem[i] == "vendor" {
+			elem[i] = repl
+		}
+	}
+	return strings.Join(elem, "/")
+}

vendor/golang.org/x/tools/go/packages/loadmode_string.go

@@ -0,0 +1,57 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packages
+
+import (
+	"fmt"
+	"strings"
+)
+
+var allModes = []LoadMode{
+	NeedName,
+	NeedFiles,
+	NeedCompiledGoFiles,
+	NeedImports,
+	NeedDeps,
+	NeedExportFile,
+	NeedTypes,
+	NeedSyntax,
+	NeedTypesInfo,
+	NeedTypesSizes,
+}
+
+var modeStrings = []string{
+	"NeedName",
+	"NeedFiles",
+	"NeedCompiledGoFiles",
+	"NeedImports",
+	"NeedDeps",
+	"NeedExportFile",
+	"NeedTypes",
+	"NeedSyntax",
+	"NeedTypesInfo",
+	"NeedTypesSizes",
+}
+
+func (mod LoadMode) String() string {
+	m := mod
+	if m == 0 {
+		return "LoadMode(0)"
+	}
+	var out []string
+	for i, x := range allModes {
+		if x > m {
+			break
+		}
+		if (m & x) != 0 {
+			out = append(out, modeStrings[i])
+			m = m ^ x
+		}
+	}
+	if m != 0 {
+		out = append(out, "Unknown")
+	}
+	return fmt.Sprintf("LoadMode(%s)", strings.Join(out, "|"))
+}

vendor/golang.org/x/tools/go/packages/visit.go

@@ -0,0 +1,59 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package packages
+
+import (
+	"fmt"
+	"os"
+	"sort"
+)
+
+// Visit visits all the packages in the import graph whose roots are
+// pkgs, calling the optional pre function the first time each package
+// is encountered (preorder), and the optional post function after a
+// package's dependencies have been visited (postorder).
+// The boolean result of pre(pkg) determines whether
+// the imports of package pkg are visited.
+func Visit(pkgs []*Package, pre func(*Package) bool, post func(*Package)) {
+	seen := make(map[*Package]bool)
+	var visit func(*Package)
+	visit = func(pkg *Package) {
+		if !seen[pkg] {
+			seen[pkg] = true
+
+			if pre == nil || pre(pkg) {
+				paths := make([]string, 0, len(pkg.Imports))
+				for path := range pkg.Imports {
+					paths = append(paths, path)
+				}
+				sort.Strings(paths) // Imports is a map, this makes visit stable
+				for _, path := range paths {
+					visit(pkg.Imports[path])
+				}
+			}
+
+			if post != nil {
+				post(pkg)
+			}
+		}
+	}
+	for _, pkg := range pkgs {
+		visit(pkg)
+	}
+}
+
+// PrintErrors prints to os.Stderr the accumulated errors of all
+// packages in the import graph rooted at pkgs, dependencies first.
+// PrintErrors returns the number of errors printed.
+func PrintErrors(pkgs []*Package) int {
+	var n int
+	Visit(pkgs, nil, func(pkg *Package) {
+		for _, err := range pkg.Errors {
+			fmt.Fprintln(os.Stderr, err)
+			n++
+		}
+	})
+	return n
+}

vendor/golang.org/x/tools/internal/event/core/event.go

@@ -0,0 +1,85 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package core provides support for event based telemetry.
+package core
+
+import (
+	"fmt"
+	"time"
+
+	"golang.org/x/tools/internal/event/label"
+)
+
+// Event holds the information about an event of note that occurred.
+type Event struct {
+	at time.Time
+
+	// As events are often on the stack, storing the first few labels directly
+	// in the event can avoid an allocation at all for the very common cases of
+	// simple events.
+	// The length needs to be large enough to cope with the majority of events
+	// but no so large as to cause undue stack pressure.
+	// A log message with two values will use 3 labels (one for each value and
+	// one for the message itself).
+
+	static  [3]label.Label // inline storage for the first few labels
+	dynamic []label.Label  // dynamically sized storage for remaining labels
+}
+
+// eventLabelMap implements label.Map for a the labels of an Event.
+type eventLabelMap struct {
+	event Event
+}
+
+func (ev Event) At() time.Time { return ev.at }
+
+func (ev Event) Format(f fmt.State, r rune) {
+	if !ev.at.IsZero() {
+		fmt.Fprint(f, ev.at.Format("2006/01/02 15:04:05 "))
+	}
+	for index := 0; ev.Valid(index); index++ {
+		if l := ev.Label(index); l.Valid() {
+			fmt.Fprintf(f, "\n\t%v", l)
+		}
+	}
+}
+
+func (ev Event) Valid(index int) bool {
+	return index >= 0 && index < len(ev.static)+len(ev.dynamic)
+}
+
+func (ev Event) Label(index int) label.Label {
+	if index < len(ev.static) {
+		return ev.static[index]
+	}
+	return ev.dynamic[index-len(ev.static)]
+}
+
+func (ev Event) Find(key label.Key) label.Label {
+	for _, l := range ev.static {
+		if l.Key() == key {
+			return l
+		}
+	}
+	for _, l := range ev.dynamic {
+		if l.Key() == key {
+			return l
+		}
+	}
+	return label.Label{}
+}
+
+func MakeEvent(static [3]label.Label, labels []label.Label) Event {
+	return Event{
+		static:  static,
+		dynamic: labels,
+	}
+}
+
+// CloneEvent event returns a copy of the event with the time adjusted to at.
+func CloneEvent(ev Event, at time.Time) Event {
+	ev.at = at
+	return ev
+}

vendor/golang.org/x/tools/internal/event/core/export.go

@@ -0,0 +1,70 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package core
+
+import (
+	"context"
+	"sync/atomic"
+	"time"
+	"unsafe"
+
+	"golang.org/x/tools/internal/event/label"
+)
+
+// Exporter is a function that handles events.
+// It may return a modified context and event.
+type Exporter func(context.Context, Event, label.Map) context.Context
+
+var (
+	exporter unsafe.Pointer
+)
+
+// SetExporter sets the global exporter function that handles all events.
+// The exporter is called synchronously from the event call site, so it should
+// return quickly so as not to hold up user code.
+func SetExporter(e Exporter) {
+	p := unsafe.Pointer(&e)
+	if e == nil {
+		// &e is always valid, and so p is always valid, but for the early abort
+		// of ProcessEvent to be efficient it needs to make the nil check on the
+		// pointer without having to dereference it, so we make the nil function
+		// also a nil pointer
+		p = nil
+	}
+	atomic.StorePointer(&exporter, p)
+}
+
+// deliver is called to deliver an event to the supplied exporter.
+// it will fill in the time.
+func deliver(ctx context.Context, exporter Exporter, ev Event) context.Context {
+	// add the current time to the event
+	ev.at = time.Now()
+	// hand the event off to the current exporter
+	return exporter(ctx, ev, ev)
+}
+
+// Export is called to deliver an event to the global exporter if set.
+func Export(ctx context.Context, ev Event) context.Context {
+	// get the global exporter and abort early if there is not one
+	exporterPtr := (*Exporter)(atomic.LoadPointer(&exporter))
+	if exporterPtr == nil {
+		return ctx
+	}
+	return deliver(ctx, *exporterPtr, ev)
+}
+
+// ExportPair is called to deliver a start event to the supplied exporter.
+// It also returns a function that will deliver the end event to the same
+// exporter.
+// It will fill in the time.
+func ExportPair(ctx context.Context, begin, end Event) (context.Context, func()) {
+	// get the global exporter and abort early if there is not one
+	exporterPtr := (*Exporter)(atomic.LoadPointer(&exporter))
+	if exporterPtr == nil {
+		return ctx, func() {}
+	}
+	ctx = deliver(ctx, *exporterPtr, begin)
+	return ctx, func() { deliver(ctx, *exporterPtr, end) }
+}

vendor/golang.org/x/tools/internal/event/core/fast.go

@@ -0,0 +1,77 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package core
+
+import (
+	"context"
+
+	"golang.org/x/tools/internal/event/keys"
+	"golang.org/x/tools/internal/event/label"
+)
+
+// Log1 takes a message and one label delivers a log event to the exporter.
+// It is a customized version of Print that is faster and does no allocation.
+func Log1(ctx context.Context, message string, t1 label.Label) {
+	Export(ctx, MakeEvent([3]label.Label{
+		keys.Msg.Of(message),
+		t1,
+	}, nil))
+}
+
+// Log2 takes a message and two labels and delivers a log event to the exporter.
+// It is a customized version of Print that is faster and does no allocation.
+func Log2(ctx context.Context, message string, t1 label.Label, t2 label.Label) {
+	Export(ctx, MakeEvent([3]label.Label{
+		keys.Msg.Of(message),
+		t1,
+		t2,
+	}, nil))
+}
+
+// Metric1 sends a label event to the exporter with the supplied labels.
+func Metric1(ctx context.Context, t1 label.Label) context.Context {
+	return Export(ctx, MakeEvent([3]label.Label{
+		keys.Metric.New(),
+		t1,
+	}, nil))
+}
+
+// Metric2 sends a label event to the exporter with the supplied labels.
+func Metric2(ctx context.Context, t1, t2 label.Label) context.Context {
+	return Export(ctx, MakeEvent([3]label.Label{
+		keys.Metric.New(),
+		t1,
+		t2,
+	}, nil))
+}
+
+// Start1 sends a span start event with the supplied label list to the exporter.
+// It also returns a function that will end the span, which should normally be
+// deferred.
+func Start1(ctx context.Context, name string, t1 label.Label) (context.Context, func()) {
+	return ExportPair(ctx,
+		MakeEvent([3]label.Label{
+			keys.Start.Of(name),
+			t1,
+		}, nil),
+		MakeEvent([3]label.Label{
+			keys.End.New(),
+		}, nil))
+}
+
+// Start2 sends a span start event with the supplied label list to the exporter.
+// It also returns a function that will end the span, which should normally be
+// deferred.
+func Start2(ctx context.Context, name string, t1, t2 label.Label) (context.Context, func()) {
+	return ExportPair(ctx,
+		MakeEvent([3]label.Label{
+			keys.Start.Of(name),
+			t1,
+			t2,
+		}, nil),
+		MakeEvent([3]label.Label{
+			keys.End.New(),
+		}, nil))
+}

vendor/golang.org/x/tools/internal/event/doc.go

@@ -0,0 +1,7 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package event provides a set of packages that cover the main
+// concepts of telemetry in an implementation agnostic way.
+package event

vendor/golang.org/x/tools/internal/event/event.go

@@ -0,0 +1,127 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package event
+
+import (
+	"context"
+
+	"golang.org/x/tools/internal/event/core"
+	"golang.org/x/tools/internal/event/keys"
+	"golang.org/x/tools/internal/event/label"
+)
+
+// Exporter is a function that handles events.
+// It may return a modified context and event.
+type Exporter func(context.Context, core.Event, label.Map) context.Context
+
+// SetExporter sets the global exporter function that handles all events.
+// The exporter is called synchronously from the event call site, so it should
+// return quickly so as not to hold up user code.
+func SetExporter(e Exporter) {
+	core.SetExporter(core.Exporter(e))
+}
+
+// Log takes a message and a label list and combines them into a single event
+// before delivering them to the exporter.
+func Log(ctx context.Context, message string, labels ...label.Label) {
+	core.Export(ctx, core.MakeEvent([3]label.Label{
+		keys.Msg.Of(message),
+	}, labels))
+}
+
+// IsLog returns true if the event was built by the Log function.
+// It is intended to be used in exporters to identify the semantics of the
+// event when deciding what to do with it.
+func IsLog(ev core.Event) bool {
+	return ev.Label(0).Key() == keys.Msg
+}
+
+// Error takes a message and a label list and combines them into a single event
+// before delivering them to the exporter. It captures the error in the
+// delivered event.
+func Error(ctx context.Context, message string, err error, labels ...label.Label) {
+	core.Export(ctx, core.MakeEvent([3]label.Label{
+		keys.Msg.Of(message),
+		keys.Err.Of(err),
+	}, labels))
+}
+
+// IsError returns true if the event was built by the Error function.
+// It is intended to be used in exporters to identify the semantics of the
+// event when deciding what to do with it.
+func IsError(ev core.Event) bool {
+	return ev.Label(0).Key() == keys.Msg &&
+		ev.Label(1).Key() == keys.Err
+}
+
+// Metric sends a label event to the exporter with the supplied labels.
+func Metric(ctx context.Context, labels ...label.Label) {
+	core.Export(ctx, core.MakeEvent([3]label.Label{
+		keys.Metric.New(),
+	}, labels))
+}
+
+// IsMetric returns true if the event was built by the Metric function.
+// It is intended to be used in exporters to identify the semantics of the
+// event when deciding what to do with it.
+func IsMetric(ev core.Event) bool {
+	return ev.Label(0).Key() == keys.Metric
+}
+
+// Label sends a label event to the exporter with the supplied labels.
+func Label(ctx context.Context, labels ...label.Label) context.Context {
+	return core.Export(ctx, core.MakeEvent([3]label.Label{
+		keys.Label.New(),
+	}, labels))
+}
+
+// IsLabel returns true if the event was built by the Label function.
+// It is intended to be used in exporters to identify the semantics of the
+// event when deciding what to do with it.
+func IsLabel(ev core.Event) bool {
+	return ev.Label(0).Key() == keys.Label
+}
+
+// Start sends a span start event with the supplied label list to the exporter.
+// It also returns a function that will end the span, which should normally be
+// deferred.
+func Start(ctx context.Context, name string, labels ...label.Label) (context.Context, func()) {
+	return core.ExportPair(ctx,
+		core.MakeEvent([3]label.Label{
+			keys.Start.Of(name),
+		}, labels),
+		core.MakeEvent([3]label.Label{
+			keys.End.New(),
+		}, nil))
+}
+
+// IsStart returns true if the event was built by the Start function.
+// It is intended to be used in exporters to identify the semantics of the
+// event when deciding what to do with it.
+func IsStart(ev core.Event) bool {
+	return ev.Label(0).Key() == keys.Start
+}
+
+// IsEnd returns true if the event was built by the End function.
+// It is intended to be used in exporters to identify the semantics of the
+// event when deciding what to do with it.
+func IsEnd(ev core.Event) bool {
+	return ev.Label(0).Key() == keys.End
+}
+
+// Detach returns a context without an associated span.
+// This allows the creation of spans that are not children of the current span.
+func Detach(ctx context.Context) context.Context {
+	return core.Export(ctx, core.MakeEvent([3]label.Label{
+		keys.Detach.New(),
+	}, nil))
+}
+
+// IsDetach returns true if the event was built by the Detach function.
+// It is intended to be used in exporters to identify the semantics of the
+// event when deciding what to do with it.
+func IsDetach(ev core.Event) bool {
+	return ev.Label(0).Key() == keys.Detach
+}

vendor/golang.org/x/tools/internal/event/keys/keys.go

@@ -0,0 +1,564 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package keys
+
+import (
+	"fmt"
+	"io"
+	"math"
+	"strconv"
+
+	"golang.org/x/tools/internal/event/label"
+)
+
+// Value represents a key for untyped values.
+type Value struct {
+	name        string
+	description string
+}
+
+// New creates a new Key for untyped values.
+func New(name, description string) *Value {
+	return &Value{name: name, description: description}
+}
+
+func (k *Value) Name() string        { return k.name }
+func (k *Value) Description() string { return k.description }
+
+func (k *Value) Format(w io.Writer, buf []byte, l label.Label) {
+	fmt.Fprint(w, k.From(l))
+}
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Value) Get(lm label.Map) interface{} {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return nil
+}
+
+// From can be used to get a value from a Label.
+func (k *Value) From(t label.Label) interface{} { return t.UnpackValue() }
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Value) Of(value interface{}) label.Label { return label.OfValue(k, value) }
+
+// Tag represents a key for tagging labels that have no value.
+// These are used when the existence of the label is the entire information it
+// carries, such as marking events to be of a specific kind, or from a specific
+// package.
+type Tag struct {
+	name        string
+	description string
+}
+
+// NewTag creates a new Key for tagging labels.
+func NewTag(name, description string) *Tag {
+	return &Tag{name: name, description: description}
+}
+
+func (k *Tag) Name() string        { return k.name }
+func (k *Tag) Description() string { return k.description }
+
+func (k *Tag) Format(w io.Writer, buf []byte, l label.Label) {}
+
+// New creates a new Label with this key.
+func (k *Tag) New() label.Label { return label.OfValue(k, nil) }
+
+// Int represents a key
+type Int struct {
+	name        string
+	description string
+}
+
+// NewInt creates a new Key for int values.
+func NewInt(name, description string) *Int {
+	return &Int{name: name, description: description}
+}
+
+func (k *Int) Name() string        { return k.name }
+func (k *Int) Description() string { return k.description }
+
+func (k *Int) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendInt(buf, int64(k.From(l)), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Int) Of(v int) label.Label { return label.Of64(k, uint64(v)) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Int) Get(lm label.Map) int {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *Int) From(t label.Label) int { return int(t.Unpack64()) }
+
+// Int8 represents a key
+type Int8 struct {
+	name        string
+	description string
+}
+
+// NewInt8 creates a new Key for int8 values.
+func NewInt8(name, description string) *Int8 {
+	return &Int8{name: name, description: description}
+}
+
+func (k *Int8) Name() string        { return k.name }
+func (k *Int8) Description() string { return k.description }
+
+func (k *Int8) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendInt(buf, int64(k.From(l)), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Int8) Of(v int8) label.Label { return label.Of64(k, uint64(v)) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Int8) Get(lm label.Map) int8 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *Int8) From(t label.Label) int8 { return int8(t.Unpack64()) }
+
+// Int16 represents a key
+type Int16 struct {
+	name        string
+	description string
+}
+
+// NewInt16 creates a new Key for int16 values.
+func NewInt16(name, description string) *Int16 {
+	return &Int16{name: name, description: description}
+}
+
+func (k *Int16) Name() string        { return k.name }
+func (k *Int16) Description() string { return k.description }
+
+func (k *Int16) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendInt(buf, int64(k.From(l)), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Int16) Of(v int16) label.Label { return label.Of64(k, uint64(v)) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Int16) Get(lm label.Map) int16 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *Int16) From(t label.Label) int16 { return int16(t.Unpack64()) }
+
+// Int32 represents a key
+type Int32 struct {
+	name        string
+	description string
+}
+
+// NewInt32 creates a new Key for int32 values.
+func NewInt32(name, description string) *Int32 {
+	return &Int32{name: name, description: description}
+}
+
+func (k *Int32) Name() string        { return k.name }
+func (k *Int32) Description() string { return k.description }
+
+func (k *Int32) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendInt(buf, int64(k.From(l)), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Int32) Of(v int32) label.Label { return label.Of64(k, uint64(v)) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Int32) Get(lm label.Map) int32 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *Int32) From(t label.Label) int32 { return int32(t.Unpack64()) }
+
+// Int64 represents a key
+type Int64 struct {
+	name        string
+	description string
+}
+
+// NewInt64 creates a new Key for int64 values.
+func NewInt64(name, description string) *Int64 {
+	return &Int64{name: name, description: description}
+}
+
+func (k *Int64) Name() string        { return k.name }
+func (k *Int64) Description() string { return k.description }
+
+func (k *Int64) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendInt(buf, k.From(l), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Int64) Of(v int64) label.Label { return label.Of64(k, uint64(v)) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Int64) Get(lm label.Map) int64 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *Int64) From(t label.Label) int64 { return int64(t.Unpack64()) }
+
+// UInt represents a key
+type UInt struct {
+	name        string
+	description string
+}
+
+// NewUInt creates a new Key for uint values.
+func NewUInt(name, description string) *UInt {
+	return &UInt{name: name, description: description}
+}
+
+func (k *UInt) Name() string        { return k.name }
+func (k *UInt) Description() string { return k.description }
+
+func (k *UInt) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendUint(buf, uint64(k.From(l)), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *UInt) Of(v uint) label.Label { return label.Of64(k, uint64(v)) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *UInt) Get(lm label.Map) uint {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *UInt) From(t label.Label) uint { return uint(t.Unpack64()) }
+
+// UInt8 represents a key
+type UInt8 struct {
+	name        string
+	description string
+}
+
+// NewUInt8 creates a new Key for uint8 values.
+func NewUInt8(name, description string) *UInt8 {
+	return &UInt8{name: name, description: description}
+}
+
+func (k *UInt8) Name() string        { return k.name }
+func (k *UInt8) Description() string { return k.description }
+
+func (k *UInt8) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendUint(buf, uint64(k.From(l)), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *UInt8) Of(v uint8) label.Label { return label.Of64(k, uint64(v)) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *UInt8) Get(lm label.Map) uint8 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *UInt8) From(t label.Label) uint8 { return uint8(t.Unpack64()) }
+
+// UInt16 represents a key
+type UInt16 struct {
+	name        string
+	description string
+}
+
+// NewUInt16 creates a new Key for uint16 values.
+func NewUInt16(name, description string) *UInt16 {
+	return &UInt16{name: name, description: description}
+}
+
+func (k *UInt16) Name() string        { return k.name }
+func (k *UInt16) Description() string { return k.description }
+
+func (k *UInt16) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendUint(buf, uint64(k.From(l)), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *UInt16) Of(v uint16) label.Label { return label.Of64(k, uint64(v)) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *UInt16) Get(lm label.Map) uint16 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *UInt16) From(t label.Label) uint16 { return uint16(t.Unpack64()) }
+
+// UInt32 represents a key
+type UInt32 struct {
+	name        string
+	description string
+}
+
+// NewUInt32 creates a new Key for uint32 values.
+func NewUInt32(name, description string) *UInt32 {
+	return &UInt32{name: name, description: description}
+}
+
+func (k *UInt32) Name() string        { return k.name }
+func (k *UInt32) Description() string { return k.description }
+
+func (k *UInt32) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendUint(buf, uint64(k.From(l)), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *UInt32) Of(v uint32) label.Label { return label.Of64(k, uint64(v)) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *UInt32) Get(lm label.Map) uint32 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *UInt32) From(t label.Label) uint32 { return uint32(t.Unpack64()) }
+
+// UInt64 represents a key
+type UInt64 struct {
+	name        string
+	description string
+}
+
+// NewUInt64 creates a new Key for uint64 values.
+func NewUInt64(name, description string) *UInt64 {
+	return &UInt64{name: name, description: description}
+}
+
+func (k *UInt64) Name() string        { return k.name }
+func (k *UInt64) Description() string { return k.description }
+
+func (k *UInt64) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendUint(buf, k.From(l), 10))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *UInt64) Of(v uint64) label.Label { return label.Of64(k, v) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *UInt64) Get(lm label.Map) uint64 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *UInt64) From(t label.Label) uint64 { return t.Unpack64() }
+
+// Float32 represents a key
+type Float32 struct {
+	name        string
+	description string
+}
+
+// NewFloat32 creates a new Key for float32 values.
+func NewFloat32(name, description string) *Float32 {
+	return &Float32{name: name, description: description}
+}
+
+func (k *Float32) Name() string        { return k.name }
+func (k *Float32) Description() string { return k.description }
+
+func (k *Float32) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendFloat(buf, float64(k.From(l)), 'E', -1, 32))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Float32) Of(v float32) label.Label {
+	return label.Of64(k, uint64(math.Float32bits(v)))
+}
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Float32) Get(lm label.Map) float32 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *Float32) From(t label.Label) float32 {
+	return math.Float32frombits(uint32(t.Unpack64()))
+}
+
+// Float64 represents a key
+type Float64 struct {
+	name        string
+	description string
+}
+
+// NewFloat64 creates a new Key for int64 values.
+func NewFloat64(name, description string) *Float64 {
+	return &Float64{name: name, description: description}
+}
+
+func (k *Float64) Name() string        { return k.name }
+func (k *Float64) Description() string { return k.description }
+
+func (k *Float64) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendFloat(buf, k.From(l), 'E', -1, 64))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Float64) Of(v float64) label.Label {
+	return label.Of64(k, math.Float64bits(v))
+}
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Float64) Get(lm label.Map) float64 {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return 0
+}
+
+// From can be used to get a value from a Label.
+func (k *Float64) From(t label.Label) float64 {
+	return math.Float64frombits(t.Unpack64())
+}
+
+// String represents a key
+type String struct {
+	name        string
+	description string
+}
+
+// NewString creates a new Key for int64 values.
+func NewString(name, description string) *String {
+	return &String{name: name, description: description}
+}
+
+func (k *String) Name() string        { return k.name }
+func (k *String) Description() string { return k.description }
+
+func (k *String) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendQuote(buf, k.From(l)))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *String) Of(v string) label.Label { return label.OfString(k, v) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *String) Get(lm label.Map) string {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return ""
+}
+
+// From can be used to get a value from a Label.
+func (k *String) From(t label.Label) string { return t.UnpackString() }
+
+// Boolean represents a key
+type Boolean struct {
+	name        string
+	description string
+}
+
+// NewBoolean creates a new Key for bool values.
+func NewBoolean(name, description string) *Boolean {
+	return &Boolean{name: name, description: description}
+}
+
+func (k *Boolean) Name() string        { return k.name }
+func (k *Boolean) Description() string { return k.description }
+
+func (k *Boolean) Format(w io.Writer, buf []byte, l label.Label) {
+	w.Write(strconv.AppendBool(buf, k.From(l)))
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Boolean) Of(v bool) label.Label {
+	if v {
+		return label.Of64(k, 1)
+	}
+	return label.Of64(k, 0)
+}
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Boolean) Get(lm label.Map) bool {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return false
+}
+
+// From can be used to get a value from a Label.
+func (k *Boolean) From(t label.Label) bool { return t.Unpack64() > 0 }
+
+// Error represents a key
+type Error struct {
+	name        string
+	description string
+}
+
+// NewError creates a new Key for int64 values.
+func NewError(name, description string) *Error {
+	return &Error{name: name, description: description}
+}
+
+func (k *Error) Name() string        { return k.name }
+func (k *Error) Description() string { return k.description }
+
+func (k *Error) Format(w io.Writer, buf []byte, l label.Label) {
+	io.WriteString(w, k.From(l).Error())
+}
+
+// Of creates a new Label with this key and the supplied value.
+func (k *Error) Of(v error) label.Label { return label.OfValue(k, v) }
+
+// Get can be used to get a label for the key from a label.Map.
+func (k *Error) Get(lm label.Map) error {
+	if t := lm.Find(k); t.Valid() {
+		return k.From(t)
+	}
+	return nil
+}
+
+// From can be used to get a value from a Label.
+func (k *Error) From(t label.Label) error {
+	err, _ := t.UnpackValue().(error)
+	return err
+}

vendor/golang.org/x/tools/internal/event/keys/standard.go

@@ -0,0 +1,22 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package keys
+
+var (
+	// Msg is a key used to add message strings to label lists.
+	Msg = NewString("message", "a readable message")
+	// Label is a key used to indicate an event adds labels to the context.
+	Label = NewTag("label", "a label context marker")
+	// Start is used for things like traces that have a name.
+	Start = NewString("start", "span start")
+	// Metric is a key used to indicate an event records metrics.
+	End = NewTag("end", "a span end marker")
+	// Metric is a key used to indicate an event records metrics.
+	Detach = NewTag("detach", "a span detach marker")
+	// Err is a key used to add error values to label lists.
+	Err = NewError("error", "an error that occurred")
+	// Metric is a key used to indicate an event records metrics.
+	Metric = NewTag("metric", "a metric event marker")
+)

vendor/golang.org/x/tools/internal/event/label/label.go

@@ -0,0 +1,215 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package label
+
+import (
+	"fmt"
+	"io"
+	"reflect"
+	"unsafe"
+)
+
+// Key is used as the identity of a Label.
+// Keys are intended to be compared by pointer only, the name should be unique
+// for communicating with external systems, but it is not required or enforced.
+type Key interface {
+	// Name returns the key name.
+	Name() string
+	// Description returns a string that can be used to describe the value.
+	Description() string
+
+	// Format is used in formatting to append the value of the label to the
+	// supplied buffer.
+	// The formatter may use the supplied buf as a scratch area to avoid
+	// allocations.
+	Format(w io.Writer, buf []byte, l Label)
+}
+
+// Label holds a key and value pair.
+// It is normally used when passing around lists of labels.
+type Label struct {
+	key     Key
+	packed  uint64
+	untyped interface{}
+}
+
+// Map is the interface to a collection of Labels indexed by key.
+type Map interface {
+	// Find returns the label that matches the supplied key.
+	Find(key Key) Label
+}
+
+// List is the interface to something that provides an iterable
+// list of labels.
+// Iteration should start from 0 and continue until Valid returns false.
+type List interface {
+	// Valid returns true if the index is within range for the list.
+	// It does not imply the label at that index will itself be valid.
+	Valid(index int) bool
+	// Label returns the label at the given index.
+	Label(index int) Label
+}
+
+// list implements LabelList for a list of Labels.
+type list struct {
+	labels []Label
+}
+
+// filter wraps a LabelList filtering out specific labels.
+type filter struct {
+	keys       []Key
+	underlying List
+}
+
+// listMap implements LabelMap for a simple list of labels.
+type listMap struct {
+	labels []Label
+}
+
+// mapChain implements LabelMap for a list of underlying LabelMap.
+type mapChain struct {
+	maps []Map
+}
+
+// OfValue creates a new label from the key and value.
+// This method is for implementing new key types, label creation should
+// normally be done with the Of method of the key.
+func OfValue(k Key, value interface{}) Label { return Label{key: k, untyped: value} }
+
+// UnpackValue assumes the label was built using LabelOfValue and returns the value
+// that was passed to that constructor.
+// This method is for implementing new key types, for type safety normal
+// access should be done with the From method of the key.
+func (t Label) UnpackValue() interface{} { return t.untyped }
+
+// Of64 creates a new label from a key and a uint64. This is often
+// used for non uint64 values that can be packed into a uint64.
+// This method is for implementing new key types, label creation should
+// normally be done with the Of method of the key.
+func Of64(k Key, v uint64) Label { return Label{key: k, packed: v} }
+
+// Unpack64 assumes the label was built using LabelOf64 and returns the value that
+// was passed to that constructor.
+// This method is for implementing new key types, for type safety normal
+// access should be done with the From method of the key.
+func (t Label) Unpack64() uint64 { return t.packed }
+
+type stringptr unsafe.Pointer
+
+// OfString creates a new label from a key and a string.
+// This method is for implementing new key types, label creation should
+// normally be done with the Of method of the key.
+func OfString(k Key, v string) Label {
+	hdr := (*reflect.StringHeader)(unsafe.Pointer(&v))
+	return Label{
+		key:     k,
+		packed:  uint64(hdr.Len),
+		untyped: stringptr(hdr.Data),
+	}
+}
+
+// UnpackString assumes the label was built using LabelOfString and returns the
+// value that was passed to that constructor.
+// This method is for implementing new key types, for type safety normal
+// access should be done with the From method of the key.
+func (t Label) UnpackString() string {
+	var v string
+	hdr := (*reflect.StringHeader)(unsafe.Pointer(&v))
+	hdr.Data = uintptr(t.untyped.(stringptr))
+	hdr.Len = int(t.packed)
+	return v
+}
+
+// Valid returns true if the Label is a valid one (it has a key).
+func (t Label) Valid() bool { return t.key != nil }
+
+// Key returns the key of this Label.
+func (t Label) Key() Key { return t.key }
+
+// Format is used for debug printing of labels.
+func (t Label) Format(f fmt.State, r rune) {
+	if !t.Valid() {
+		io.WriteString(f, `nil`)
+		return
+	}
+	io.WriteString(f, t.Key().Name())
+	io.WriteString(f, "=")
+	var buf [128]byte
+	t.Key().Format(f, buf[:0], t)
+}
+
+func (l *list) Valid(index int) bool {
+	return index >= 0 && index < len(l.labels)
+}
+
+func (l *list) Label(index int) Label {
+	return l.labels[index]
+}
+
+func (f *filter) Valid(index int) bool {
+	return f.underlying.Valid(index)
+}
+
+func (f *filter) Label(index int) Label {
+	l := f.underlying.Label(index)
+	for _, f := range f.keys {
+		if l.Key() == f {
+			return Label{}
+		}
+	}
+	return l
+}
+
+func (lm listMap) Find(key Key) Label {
+	for _, l := range lm.labels {
+		if l.Key() == key {
+			return l
+		}
+	}
+	return Label{}
+}
+
+func (c mapChain) Find(key Key) Label {
+	for _, src := range c.maps {
+		l := src.Find(key)
+		if l.Valid() {
+			return l
+		}
+	}
+	return Label{}
+}
+
+var emptyList = &list{}
+
+func NewList(labels ...Label) List {
+	if len(labels) == 0 {
+		return emptyList
+	}
+	return &list{labels: labels}
+}
+
+func Filter(l List, keys ...Key) List {
+	if len(keys) == 0 {
+		return l
+	}
+	return &filter{keys: keys, underlying: l}
+}
+
+func NewMap(labels ...Label) Map {
+	return listMap{labels: labels}
+}
+
+func MergeMaps(srcs ...Map) Map {
+	var nonNil []Map
+	for _, src := range srcs {
+		if src != nil {
+			nonNil = append(nonNil, src)
+		}
+	}
+	if len(nonNil) == 1 {
+		return nonNil[0]
+	}
+	return mapChain{maps: nonNil}
+}

vendor/golang.org/x/tools/internal/gcimporter/bexport.go

@@ -0,0 +1,852 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Binary package export.
+// This file was derived from $GOROOT/src/cmd/compile/internal/gc/bexport.go;
+// see that file for specification of the format.
+
+package gcimporter
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"math"
+	"math/big"
+	"sort"
+	"strings"
+)
+
+// If debugFormat is set, each integer and string value is preceded by a marker
+// and position information in the encoding. This mechanism permits an importer
+// to recognize immediately when it is out of sync. The importer recognizes this
+// mode automatically (i.e., it can import export data produced with debugging
+// support even if debugFormat is not set at the time of import). This mode will
+// lead to massively larger export data (by a factor of 2 to 3) and should only
+// be enabled during development and debugging.
+//
+// NOTE: This flag is the first flag to enable if importing dies because of
+// (suspected) format errors, and whenever a change is made to the format.
+const debugFormat = false // default: false
+
+// Current export format version. Increase with each format change.
+//
+// Note: The latest binary (non-indexed) export format is at version 6.
+// This exporter is still at level 4, but it doesn't matter since
+// the binary importer can handle older versions just fine.
+//
+//	6: package height (CL 105038) -- NOT IMPLEMENTED HERE
+//	5: improved position encoding efficiency (issue 20080, CL 41619) -- NOT IMPLEMENTED HERE
+//	4: type name objects support type aliases, uses aliasTag
+//	3: Go1.8 encoding (same as version 2, aliasTag defined but never used)
+//	2: removed unused bool in ODCL export (compiler only)
+//	1: header format change (more regular), export package for _ struct fields
+//	0: Go1.7 encoding
+const exportVersion = 4
+
+// trackAllTypes enables cycle tracking for all types, not just named
+// types. The existing compiler invariants assume that unnamed types
+// that are not completely set up are not used, or else there are spurious
+// errors.
+// If disabled, only named types are tracked, possibly leading to slightly
+// less efficient encoding in rare cases. It also prevents the export of
+// some corner-case type declarations (but those are not handled correctly
+// with with the textual export format either).
+// TODO(gri) enable and remove once issues caused by it are fixed
+const trackAllTypes = false
+
+type exporter struct {
+	fset *token.FileSet
+	out  bytes.Buffer
+
+	// object -> index maps, indexed in order of serialization
+	strIndex map[string]int
+	pkgIndex map[*types.Package]int
+	typIndex map[types.Type]int
+
+	// position encoding
+	posInfoFormat bool
+	prevFile      string
+	prevLine      int
+
+	// debugging support
+	written int // bytes written
+	indent  int // for trace
+}
+
+// internalError represents an error generated inside this package.
+type internalError string
+
+func (e internalError) Error() string { return "gcimporter: " + string(e) }
+
+func internalErrorf(format string, args ...interface{}) error {
+	return internalError(fmt.Sprintf(format, args...))
+}
+
+// BExportData returns binary export data for pkg.
+// If no file set is provided, position info will be missing.
+func BExportData(fset *token.FileSet, pkg *types.Package) (b []byte, err error) {
+	if !debug {
+		defer func() {
+			if e := recover(); e != nil {
+				if ierr, ok := e.(internalError); ok {
+					err = ierr
+					return
+				}
+				// Not an internal error; panic again.
+				panic(e)
+			}
+		}()
+	}
+
+	p := exporter{
+		fset:          fset,
+		strIndex:      map[string]int{"": 0}, // empty string is mapped to 0
+		pkgIndex:      make(map[*types.Package]int),
+		typIndex:      make(map[types.Type]int),
+		posInfoFormat: true, // TODO(gri) might become a flag, eventually
+	}
+
+	// write version info
+	// The version string must start with "version %d" where %d is the version
+	// number. Additional debugging information may follow after a blank; that
+	// text is ignored by the importer.
+	p.rawStringln(fmt.Sprintf("version %d", exportVersion))
+	var debug string
+	if debugFormat {
+		debug = "debug"
+	}
+	p.rawStringln(debug) // cannot use p.bool since it's affected by debugFormat; also want to see this clearly
+	p.bool(trackAllTypes)
+	p.bool(p.posInfoFormat)
+
+	// --- generic export data ---
+
+	// populate type map with predeclared "known" types
+	for index, typ := range predeclared() {
+		p.typIndex[typ] = index
+	}
+	if len(p.typIndex) != len(predeclared()) {
+		return nil, internalError("duplicate entries in type map?")
+	}
+
+	// write package data
+	p.pkg(pkg, true)
+	if trace {
+		p.tracef("\n")
+	}
+
+	// write objects
+	objcount := 0
+	scope := pkg.Scope()
+	for _, name := range scope.Names() {
+		if !token.IsExported(name) {
+			continue
+		}
+		if trace {
+			p.tracef("\n")
+		}
+		p.obj(scope.Lookup(name))
+		objcount++
+	}
+
+	// indicate end of list
+	if trace {
+		p.tracef("\n")
+	}
+	p.tag(endTag)
+
+	// for self-verification only (redundant)
+	p.int(objcount)
+
+	if trace {
+		p.tracef("\n")
+	}
+
+	// --- end of export data ---
+
+	return p.out.Bytes(), nil
+}
+
+func (p *exporter) pkg(pkg *types.Package, emptypath bool) {
+	if pkg == nil {
+		panic(internalError("unexpected nil pkg"))
+	}
+
+	// if we saw the package before, write its index (>= 0)
+	if i, ok := p.pkgIndex[pkg]; ok {
+		p.index('P', i)
+		return
+	}
+
+	// otherwise, remember the package, write the package tag (< 0) and package data
+	if trace {
+		p.tracef("P%d = { ", len(p.pkgIndex))
+		defer p.tracef("} ")
+	}
+	p.pkgIndex[pkg] = len(p.pkgIndex)
+
+	p.tag(packageTag)
+	p.string(pkg.Name())
+	if emptypath {
+		p.string("")
+	} else {
+		p.string(pkg.Path())
+	}
+}
+
+func (p *exporter) obj(obj types.Object) {
+	switch obj := obj.(type) {
+	case *types.Const:
+		p.tag(constTag)
+		p.pos(obj)
+		p.qualifiedName(obj)
+		p.typ(obj.Type())
+		p.value(obj.Val())
+
+	case *types.TypeName:
+		if obj.IsAlias() {
+			p.tag(aliasTag)
+			p.pos(obj)
+			p.qualifiedName(obj)
+		} else {
+			p.tag(typeTag)
+		}
+		p.typ(obj.Type())
+
+	case *types.Var:
+		p.tag(varTag)
+		p.pos(obj)
+		p.qualifiedName(obj)
+		p.typ(obj.Type())
+
+	case *types.Func:
+		p.tag(funcTag)
+		p.pos(obj)
+		p.qualifiedName(obj)
+		sig := obj.Type().(*types.Signature)
+		p.paramList(sig.Params(), sig.Variadic())
+		p.paramList(sig.Results(), false)
+
+	default:
+		panic(internalErrorf("unexpected object %v (%T)", obj, obj))
+	}
+}
+
+func (p *exporter) pos(obj types.Object) {
+	if !p.posInfoFormat {
+		return
+	}
+
+	file, line := p.fileLine(obj)
+	if file == p.prevFile {
+		// common case: write line delta
+		// delta == 0 means different file or no line change
+		delta := line - p.prevLine
+		p.int(delta)
+		if delta == 0 {
+			p.int(-1) // -1 means no file change
+		}
+	} else {
+		// different file
+		p.int(0)
+		// Encode filename as length of common prefix with previous
+		// filename, followed by (possibly empty) suffix. Filenames
+		// frequently share path prefixes, so this can save a lot
+		// of space and make export data size less dependent on file
+		// path length. The suffix is unlikely to be empty because
+		// file names tend to end in ".go".
+		n := commonPrefixLen(p.prevFile, file)
+		p.int(n)           // n >= 0
+		p.string(file[n:]) // write suffix only
+		p.prevFile = file
+		p.int(line)
+	}
+	p.prevLine = line
+}
+
+func (p *exporter) fileLine(obj types.Object) (file string, line int) {
+	if p.fset != nil {
+		pos := p.fset.Position(obj.Pos())
+		file = pos.Filename
+		line = pos.Line
+	}
+	return
+}
+
+func commonPrefixLen(a, b string) int {
+	if len(a) > len(b) {
+		a, b = b, a
+	}
+	// len(a) <= len(b)
+	i := 0
+	for i < len(a) && a[i] == b[i] {
+		i++
+	}
+	return i
+}
+
+func (p *exporter) qualifiedName(obj types.Object) {
+	p.string(obj.Name())
+	p.pkg(obj.Pkg(), false)
+}
+
+func (p *exporter) typ(t types.Type) {
+	if t == nil {
+		panic(internalError("nil type"))
+	}
+
+	// Possible optimization: Anonymous pointer types *T where
+	// T is a named type are common. We could canonicalize all
+	// such types *T to a single type PT = *T. This would lead
+	// to at most one *T entry in typIndex, and all future *T's
+	// would be encoded as the respective index directly. Would
+	// save 1 byte (pointerTag) per *T and reduce the typIndex
+	// size (at the cost of a canonicalization map). We can do
+	// this later, without encoding format change.
+
+	// if we saw the type before, write its index (>= 0)
+	if i, ok := p.typIndex[t]; ok {
+		p.index('T', i)
+		return
+	}
+
+	// otherwise, remember the type, write the type tag (< 0) and type data
+	if trackAllTypes {
+		if trace {
+			p.tracef("T%d = {>\n", len(p.typIndex))
+			defer p.tracef("<\n} ")
+		}
+		p.typIndex[t] = len(p.typIndex)
+	}
+
+	switch t := t.(type) {
+	case *types.Named:
+		if !trackAllTypes {
+			// if we don't track all types, track named types now
+			p.typIndex[t] = len(p.typIndex)
+		}
+
+		p.tag(namedTag)
+		p.pos(t.Obj())
+		p.qualifiedName(t.Obj())
+		p.typ(t.Underlying())
+		if !types.IsInterface(t) {
+			p.assocMethods(t)
+		}
+
+	case *types.Array:
+		p.tag(arrayTag)
+		p.int64(t.Len())
+		p.typ(t.Elem())
+
+	case *types.Slice:
+		p.tag(sliceTag)
+		p.typ(t.Elem())
+
+	case *dddSlice:
+		p.tag(dddTag)
+		p.typ(t.elem)
+
+	case *types.Struct:
+		p.tag(structTag)
+		p.fieldList(t)
+
+	case *types.Pointer:
+		p.tag(pointerTag)
+		p.typ(t.Elem())
+
+	case *types.Signature:
+		p.tag(signatureTag)
+		p.paramList(t.Params(), t.Variadic())
+		p.paramList(t.Results(), false)
+
+	case *types.Interface:
+		p.tag(interfaceTag)
+		p.iface(t)
+
+	case *types.Map:
+		p.tag(mapTag)
+		p.typ(t.Key())
+		p.typ(t.Elem())
+
+	case *types.Chan:
+		p.tag(chanTag)
+		p.int(int(3 - t.Dir())) // hack
+		p.typ(t.Elem())
+
+	default:
+		panic(internalErrorf("unexpected type %T: %s", t, t))
+	}
+}
+
+func (p *exporter) assocMethods(named *types.Named) {
+	// Sort methods (for determinism).
+	var methods []*types.Func
+	for i := 0; i < named.NumMethods(); i++ {
+		methods = append(methods, named.Method(i))
+	}
+	sort.Sort(methodsByName(methods))
+
+	p.int(len(methods))
+
+	if trace && methods != nil {
+		p.tracef("associated methods {>\n")
+	}
+
+	for i, m := range methods {
+		if trace && i > 0 {
+			p.tracef("\n")
+		}
+
+		p.pos(m)
+		name := m.Name()
+		p.string(name)
+		if !exported(name) {
+			p.pkg(m.Pkg(), false)
+		}
+
+		sig := m.Type().(*types.Signature)
+		p.paramList(types.NewTuple(sig.Recv()), false)
+		p.paramList(sig.Params(), sig.Variadic())
+		p.paramList(sig.Results(), false)
+		p.int(0) // dummy value for go:nointerface pragma - ignored by importer
+	}
+
+	if trace && methods != nil {
+		p.tracef("<\n} ")
+	}
+}
+
+type methodsByName []*types.Func
+
+func (x methodsByName) Len() int           { return len(x) }
+func (x methodsByName) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
+func (x methodsByName) Less(i, j int) bool { return x[i].Name() < x[j].Name() }
+
+func (p *exporter) fieldList(t *types.Struct) {
+	if trace && t.NumFields() > 0 {
+		p.tracef("fields {>\n")
+		defer p.tracef("<\n} ")
+	}
+
+	p.int(t.NumFields())
+	for i := 0; i < t.NumFields(); i++ {
+		if trace && i > 0 {
+			p.tracef("\n")
+		}
+		p.field(t.Field(i))
+		p.string(t.Tag(i))
+	}
+}
+
+func (p *exporter) field(f *types.Var) {
+	if !f.IsField() {
+		panic(internalError("field expected"))
+	}
+
+	p.pos(f)
+	p.fieldName(f)
+	p.typ(f.Type())
+}
+
+func (p *exporter) iface(t *types.Interface) {
+	// TODO(gri): enable importer to load embedded interfaces,
+	// then emit Embeddeds and ExplicitMethods separately here.
+	p.int(0)
+
+	n := t.NumMethods()
+	if trace && n > 0 {
+		p.tracef("methods {>\n")
+		defer p.tracef("<\n} ")
+	}
+	p.int(n)
+	for i := 0; i < n; i++ {
+		if trace && i > 0 {
+			p.tracef("\n")
+		}
+		p.method(t.Method(i))
+	}
+}
+
+func (p *exporter) method(m *types.Func) {
+	sig := m.Type().(*types.Signature)
+	if sig.Recv() == nil {
+		panic(internalError("method expected"))
+	}
+
+	p.pos(m)
+	p.string(m.Name())
+	if m.Name() != "_" && !token.IsExported(m.Name()) {
+		p.pkg(m.Pkg(), false)
+	}
+
+	// interface method; no need to encode receiver.
+	p.paramList(sig.Params(), sig.Variadic())
+	p.paramList(sig.Results(), false)
+}
+
+func (p *exporter) fieldName(f *types.Var) {
+	name := f.Name()
+
+	if f.Anonymous() {
+		// anonymous field - we distinguish between 3 cases:
+		// 1) field name matches base type name and is exported
+		// 2) field name matches base type name and is not exported
+		// 3) field name doesn't match base type name (alias name)
+		bname := basetypeName(f.Type())
+		if name == bname {
+			if token.IsExported(name) {
+				name = "" // 1) we don't need to know the field name or package
+			} else {
+				name = "?" // 2) use unexported name "?" to force package export
+			}
+		} else {
+			// 3) indicate alias and export name as is
+			// (this requires an extra "@" but this is a rare case)
+			p.string("@")
+		}
+	}
+
+	p.string(name)
+	if name != "" && !token.IsExported(name) {
+		p.pkg(f.Pkg(), false)
+	}
+}
+
+func basetypeName(typ types.Type) string {
+	switch typ := deref(typ).(type) {
+	case *types.Basic:
+		return typ.Name()
+	case *types.Named:
+		return typ.Obj().Name()
+	default:
+		return "" // unnamed type
+	}
+}
+
+func (p *exporter) paramList(params *types.Tuple, variadic bool) {
+	// use negative length to indicate unnamed parameters
+	// (look at the first parameter only since either all
+	// names are present or all are absent)
+	n := params.Len()
+	if n > 0 && params.At(0).Name() == "" {
+		n = -n
+	}
+	p.int(n)
+	for i := 0; i < params.Len(); i++ {
+		q := params.At(i)
+		t := q.Type()
+		if variadic && i == params.Len()-1 {
+			t = &dddSlice{t.(*types.Slice).Elem()}
+		}
+		p.typ(t)
+		if n > 0 {
+			name := q.Name()
+			p.string(name)
+			if name != "_" {
+				p.pkg(q.Pkg(), false)
+			}
+		}
+		p.string("") // no compiler-specific info
+	}
+}
+
+func (p *exporter) value(x constant.Value) {
+	if trace {
+		p.tracef("= ")
+	}
+
+	switch x.Kind() {
+	case constant.Bool:
+		tag := falseTag
+		if constant.BoolVal(x) {
+			tag = trueTag
+		}
+		p.tag(tag)
+
+	case constant.Int:
+		if v, exact := constant.Int64Val(x); exact {
+			// common case: x fits into an int64 - use compact encoding
+			p.tag(int64Tag)
+			p.int64(v)
+			return
+		}
+		// uncommon case: large x - use float encoding
+		// (powers of 2 will be encoded efficiently with exponent)
+		p.tag(floatTag)
+		p.float(constant.ToFloat(x))
+
+	case constant.Float:
+		p.tag(floatTag)
+		p.float(x)
+
+	case constant.Complex:
+		p.tag(complexTag)
+		p.float(constant.Real(x))
+		p.float(constant.Imag(x))
+
+	case constant.String:
+		p.tag(stringTag)
+		p.string(constant.StringVal(x))
+
+	case constant.Unknown:
+		// package contains type errors
+		p.tag(unknownTag)
+
+	default:
+		panic(internalErrorf("unexpected value %v (%T)", x, x))
+	}
+}
+
+func (p *exporter) float(x constant.Value) {
+	if x.Kind() != constant.Float {
+		panic(internalErrorf("unexpected constant %v, want float", x))
+	}
+	// extract sign (there is no -0)
+	sign := constant.Sign(x)
+	if sign == 0 {
+		// x == 0
+		p.int(0)
+		return
+	}
+	// x != 0
+
+	var f big.Float
+	if v, exact := constant.Float64Val(x); exact {
+		// float64
+		f.SetFloat64(v)
+	} else if num, denom := constant.Num(x), constant.Denom(x); num.Kind() == constant.Int {
+		// TODO(gri): add big.Rat accessor to constant.Value.
+		r := valueToRat(num)
+		f.SetRat(r.Quo(r, valueToRat(denom)))
+	} else {
+		// Value too large to represent as a fraction => inaccessible.
+		// TODO(gri): add big.Float accessor to constant.Value.
+		f.SetFloat64(math.MaxFloat64) // FIXME
+	}
+
+	// extract exponent such that 0.5 <= m < 1.0
+	var m big.Float
+	exp := f.MantExp(&m)
+
+	// extract mantissa as *big.Int
+	// - set exponent large enough so mant satisfies mant.IsInt()
+	// - get *big.Int from mant
+	m.SetMantExp(&m, int(m.MinPrec()))
+	mant, acc := m.Int(nil)
+	if acc != big.Exact {
+		panic(internalError("internal error"))
+	}
+
+	p.int(sign)
+	p.int(exp)
+	p.string(string(mant.Bytes()))
+}
+
+func valueToRat(x constant.Value) *big.Rat {
+	// Convert little-endian to big-endian.
+	// I can't believe this is necessary.
+	bytes := constant.Bytes(x)
+	for i := 0; i < len(bytes)/2; i++ {
+		bytes[i], bytes[len(bytes)-1-i] = bytes[len(bytes)-1-i], bytes[i]
+	}
+	return new(big.Rat).SetInt(new(big.Int).SetBytes(bytes))
+}
+
+func (p *exporter) bool(b bool) bool {
+	if trace {
+		p.tracef("[")
+		defer p.tracef("= %v] ", b)
+	}
+
+	x := 0
+	if b {
+		x = 1
+	}
+	p.int(x)
+	return b
+}
+
+// ----------------------------------------------------------------------------
+// Low-level encoders
+
+func (p *exporter) index(marker byte, index int) {
+	if index < 0 {
+		panic(internalError("invalid index < 0"))
+	}
+	if debugFormat {
+		p.marker('t')
+	}
+	if trace {
+		p.tracef("%c%d ", marker, index)
+	}
+	p.rawInt64(int64(index))
+}
+
+func (p *exporter) tag(tag int) {
+	if tag >= 0 {
+		panic(internalError("invalid tag >= 0"))
+	}
+	if debugFormat {
+		p.marker('t')
+	}
+	if trace {
+		p.tracef("%s ", tagString[-tag])
+	}
+	p.rawInt64(int64(tag))
+}
+
+func (p *exporter) int(x int) {
+	p.int64(int64(x))
+}
+
+func (p *exporter) int64(x int64) {
+	if debugFormat {
+		p.marker('i')
+	}
+	if trace {
+		p.tracef("%d ", x)
+	}
+	p.rawInt64(x)
+}
+
+func (p *exporter) string(s string) {
+	if debugFormat {
+		p.marker('s')
+	}
+	if trace {
+		p.tracef("%q ", s)
+	}
+	// if we saw the string before, write its index (>= 0)
+	// (the empty string is mapped to 0)
+	if i, ok := p.strIndex[s]; ok {
+		p.rawInt64(int64(i))
+		return
+	}
+	// otherwise, remember string and write its negative length and bytes
+	p.strIndex[s] = len(p.strIndex)
+	p.rawInt64(-int64(len(s)))
+	for i := 0; i < len(s); i++ {
+		p.rawByte(s[i])
+	}
+}
+
+// marker emits a marker byte and position information which makes
+// it easy for a reader to detect if it is "out of sync". Used for
+// debugFormat format only.
+func (p *exporter) marker(m byte) {
+	p.rawByte(m)
+	// Enable this for help tracking down the location
+	// of an incorrect marker when running in debugFormat.
+	if false && trace {
+		p.tracef("#%d ", p.written)
+	}
+	p.rawInt64(int64(p.written))
+}
+
+// rawInt64 should only be used by low-level encoders.
+func (p *exporter) rawInt64(x int64) {
+	var tmp [binary.MaxVarintLen64]byte
+	n := binary.PutVarint(tmp[:], x)
+	for i := 0; i < n; i++ {
+		p.rawByte(tmp[i])
+	}
+}
+
+// rawStringln should only be used to emit the initial version string.
+func (p *exporter) rawStringln(s string) {
+	for i := 0; i < len(s); i++ {
+		p.rawByte(s[i])
+	}
+	p.rawByte('\n')
+}
+
+// rawByte is the bottleneck interface to write to p.out.
+// rawByte escapes b as follows (any encoding does that
+// hides '$'):
+//
+//	'$'  => '|' 'S'
+//	'|'  => '|' '|'
+//
+// Necessary so other tools can find the end of the
+// export data by searching for "$$".
+// rawByte should only be used by low-level encoders.
+func (p *exporter) rawByte(b byte) {
+	switch b {
+	case '$':
+		// write '$' as '|' 'S'
+		b = 'S'
+		fallthrough
+	case '|':
+		// write '|' as '|' '|'
+		p.out.WriteByte('|')
+		p.written++
+	}
+	p.out.WriteByte(b)
+	p.written++
+}
+
+// tracef is like fmt.Printf but it rewrites the format string
+// to take care of indentation.
+func (p *exporter) tracef(format string, args ...interface{}) {
+	if strings.ContainsAny(format, "<>\n") {
+		var buf bytes.Buffer
+		for i := 0; i < len(format); i++ {
+			// no need to deal with runes
+			ch := format[i]
+			switch ch {
+			case '>':
+				p.indent++
+				continue
+			case '<':
+				p.indent--
+				continue
+			}
+			buf.WriteByte(ch)
+			if ch == '\n' {
+				for j := p.indent; j > 0; j-- {
+					buf.WriteString(".  ")
+				}
+			}
+		}
+		format = buf.String()
+	}
+	fmt.Printf(format, args...)
+}
+
+// Debugging support.
+// (tagString is only used when tracing is enabled)
+var tagString = [...]string{
+	// Packages
+	-packageTag: "package",
+
+	// Types
+	-namedTag:     "named type",
+	-arrayTag:     "array",
+	-sliceTag:     "slice",
+	-dddTag:       "ddd",
+	-structTag:    "struct",
+	-pointerTag:   "pointer",
+	-signatureTag: "signature",
+	-interfaceTag: "interface",
+	-mapTag:       "map",
+	-chanTag:      "chan",
+
+	// Values
+	-falseTag:    "false",
+	-trueTag:     "true",
+	-int64Tag:    "int64",
+	-floatTag:    "float",
+	-fractionTag: "fraction",
+	-complexTag:  "complex",
+	-stringTag:   "string",
+	-unknownTag:  "unknown",
+
+	// Type aliases
+	-aliasTag: "alias",
+}

vendor/golang.org/x/tools/internal/gcimporter/exportdata.go

@@ -0,0 +1,99 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file is a copy of $GOROOT/src/go/internal/gcimporter/exportdata.go.
+
+// This file implements FindExportData.
+
+package gcimporter
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+func readGopackHeader(r *bufio.Reader) (name string, size int64, err error) {
+	// See $GOROOT/include/ar.h.
+	hdr := make([]byte, 16+12+6+6+8+10+2)
+	_, err = io.ReadFull(r, hdr)
+	if err != nil {
+		return
+	}
+	// leave for debugging
+	if false {
+		fmt.Printf("header: %s", hdr)
+	}
+	s := strings.TrimSpace(string(hdr[16+12+6+6+8:][:10]))
+	length, err := strconv.Atoi(s)
+	size = int64(length)
+	if err != nil || hdr[len(hdr)-2] != '`' || hdr[len(hdr)-1] != '\n' {
+		err = fmt.Errorf("invalid archive header")
+		return
+	}
+	name = strings.TrimSpace(string(hdr[:16]))
+	return
+}
+
+// FindExportData positions the reader r at the beginning of the
+// export data section of an underlying GC-created object/archive
+// file by reading from it. The reader must be positioned at the
+// start of the file before calling this function. The hdr result
+// is the string before the export data, either "$$" or "$$B".
+// The size result is the length of the export data in bytes, or -1 if not known.
+func FindExportData(r *bufio.Reader) (hdr string, size int64, err error) {
+	// Read first line to make sure this is an object file.
+	line, err := r.ReadSlice('\n')
+	if err != nil {
+		err = fmt.Errorf("can't find export data (%v)", err)
+		return
+	}
+
+	if string(line) == "!<arch>\n" {
+		// Archive file. Scan to __.PKGDEF.
+		var name string
+		if name, size, err = readGopackHeader(r); err != nil {
+			return
+		}
+
+		// First entry should be __.PKGDEF.
+		if name != "__.PKGDEF" {
+			err = fmt.Errorf("go archive is missing __.PKGDEF")
+			return
+		}
+
+		// Read first line of __.PKGDEF data, so that line
+		// is once again the first line of the input.
+		if line, err = r.ReadSlice('\n'); err != nil {
+			err = fmt.Errorf("can't find export data (%v)", err)
+			return
+		}
+		size -= int64(len(line))
+	}
+
+	// Now at __.PKGDEF in archive or still at beginning of file.
+	// Either way, line should begin with "go object ".
+	if !strings.HasPrefix(string(line), "go object ") {
+		err = fmt.Errorf("not a Go object file")
+		return
+	}
+
+	// Skip over object header to export data.
+	// Begins after first line starting with $$.
+	for line[0] != '$' {
+		if line, err = r.ReadSlice('\n'); err != nil {
+			err = fmt.Errorf("can't find export data (%v)", err)
+			return
+		}
+		size -= int64(len(line))
+	}
+	hdr = string(line)
+	if size < 0 {
+		size = -1
+	}
+
+	return
+}

vendor/golang.org/x/tools/internal/gcimporter/iimport.go

@@ -0,0 +1,898 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Indexed package import.
+// See cmd/compile/internal/gc/iexport.go for the export data format.
+
+// This file is a copy of $GOROOT/src/go/internal/gcimporter/iimport.go.
+
+package gcimporter
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"go/constant"
+	"go/token"
+	"go/types"
+	"io"
+	"math/big"
+	"sort"
+	"strings"
+
+	"golang.org/x/tools/internal/typeparams"
+)
+
+type intReader struct {
+	*bytes.Reader
+	path string
+}
+
+func (r *intReader) int64() int64 {
+	i, err := binary.ReadVarint(r.Reader)
+	if err != nil {
+		errorf("import %q: read varint error: %v", r.path, err)
+	}
+	return i
+}
+
+func (r *intReader) uint64() uint64 {
+	i, err := binary.ReadUvarint(r.Reader)
+	if err != nil {
+		errorf("import %q: read varint error: %v", r.path, err)
+	}
+	return i
+}
+
+// Keep this in sync with constants in iexport.go.
+const (
+	iexportVersionGo1_11   = 0
+	iexportVersionPosCol   = 1
+	iexportVersionGo1_18   = 2
+	iexportVersionGenerics = 2
+
+	iexportVersionCurrent = 2
+)
+
+type ident struct {
+	pkg  *types.Package
+	name string
+}
+
+const predeclReserved = 32
+
+type itag uint64
+
+const (
+	// Types
+	definedType itag = iota
+	pointerType
+	sliceType
+	arrayType
+	chanType
+	mapType
+	signatureType
+	structType
+	interfaceType
+	typeParamType
+	instanceType
+	unionType
+)
+
+// IImportData imports a package from the serialized package data
+// and returns 0 and a reference to the package.
+// If the export data version is not recognized or the format is otherwise
+// compromised, an error is returned.
+func IImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (int, *types.Package, error) {
+	pkgs, err := iimportCommon(fset, imports, data, false, path, nil)
+	if err != nil {
+		return 0, nil, err
+	}
+	return 0, pkgs[0], nil
+}
+
+// IImportBundle imports a set of packages from the serialized package bundle.
+func IImportBundle(fset *token.FileSet, imports map[string]*types.Package, data []byte) ([]*types.Package, error) {
+	return iimportCommon(fset, imports, data, true, "", nil)
+}
+
+func iimportCommon(fset *token.FileSet, imports map[string]*types.Package, data []byte, bundle bool, path string, insert InsertType) (pkgs []*types.Package, err error) {
+	const currentVersion = iexportVersionCurrent
+	version := int64(-1)
+	if !debug {
+		defer func() {
+			if e := recover(); e != nil {
+				if bundle {
+					err = fmt.Errorf("%v", e)
+				} else if version > currentVersion {
+					err = fmt.Errorf("cannot import %q (%v), export data is newer version - update tool", path, e)
+				} else {
+					err = fmt.Errorf("cannot import %q (%v), possibly version skew - reinstall package", path, e)
+				}
+			}
+		}()
+	}
+
+	r := &intReader{bytes.NewReader(data), path}
+
+	if bundle {
+		bundleVersion := r.uint64()
+		switch bundleVersion {
+		case bundleVersion:
+		default:
+			errorf("unknown bundle format version %d", bundleVersion)
+		}
+	}
+
+	version = int64(r.uint64())
+	switch version {
+	case iexportVersionGo1_18, iexportVersionPosCol, iexportVersionGo1_11:
+	default:
+		if version > iexportVersionGo1_18 {
+			errorf("unstable iexport format version %d, just rebuild compiler and std library", version)
+		} else {
+			errorf("unknown iexport format version %d", version)
+		}
+	}
+
+	sLen := int64(r.uint64())
+	dLen := int64(r.uint64())
+
+	whence, _ := r.Seek(0, io.SeekCurrent)
+	stringData := data[whence : whence+sLen]
+	declData := data[whence+sLen : whence+sLen+dLen]
+	r.Seek(sLen+dLen, io.SeekCurrent)
+
+	p := iimporter{
+		version: int(version),
+		ipath:   path,
+		insert:  insert,
+
+		stringData:  stringData,
+		stringCache: make(map[uint64]string),
+		pkgCache:    make(map[uint64]*types.Package),
+
+		declData: declData,
+		pkgIndex: make(map[*types.Package]map[string]uint64),
+		typCache: make(map[uint64]types.Type),
+		// Separate map for typeparams, keyed by their package and unique
+		// name.
+		tparamIndex: make(map[ident]types.Type),
+
+		fake: fakeFileSet{
+			fset:  fset,
+			files: make(map[string]*fileInfo),
+		},
+	}
+	defer p.fake.setLines() // set lines for files in fset
+
+	for i, pt := range predeclared() {
+		p.typCache[uint64(i)] = pt
+	}
+
+	pkgList := make([]*types.Package, r.uint64())
+	for i := range pkgList {
+		pkgPathOff := r.uint64()
+		pkgPath := p.stringAt(pkgPathOff)
+		pkgName := p.stringAt(r.uint64())
+		_ = r.uint64() // package height; unused by go/types
+
+		if pkgPath == "" {
+			pkgPath = path
+		}
+		pkg := imports[pkgPath]
+		if pkg == nil {
+			pkg = types.NewPackage(pkgPath, pkgName)
+			imports[pkgPath] = pkg
+		} else if pkg.Name() != pkgName {
+			errorf("conflicting names %s and %s for package %q", pkg.Name(), pkgName, path)
+		}
+		if i == 0 && !bundle {
+			p.localpkg = pkg
+		}
+
+		p.pkgCache[pkgPathOff] = pkg
+
+		// Read index for package.
+		nameIndex := make(map[string]uint64)
+		nSyms := r.uint64()
+		// In shallow mode we don't expect an index for other packages.
+		assert(nSyms == 0 || p.localpkg == pkg || p.insert == nil)
+		for ; nSyms > 0; nSyms-- {
+			name := p.stringAt(r.uint64())
+			nameIndex[name] = r.uint64()
+		}
+
+		p.pkgIndex[pkg] = nameIndex
+		pkgList[i] = pkg
+	}
+
+	if bundle {
+		pkgs = make([]*types.Package, r.uint64())
+		for i := range pkgs {
+			pkg := p.pkgAt(r.uint64())
+			imps := make([]*types.Package, r.uint64())
+			for j := range imps {
+				imps[j] = p.pkgAt(r.uint64())
+			}
+			pkg.SetImports(imps)
+			pkgs[i] = pkg
+		}
+	} else {
+		if len(pkgList) == 0 {
+			errorf("no packages found for %s", path)
+			panic("unreachable")
+		}
+		pkgs = pkgList[:1]
+
+		// record all referenced packages as imports
+		list := append(([]*types.Package)(nil), pkgList[1:]...)
+		sort.Sort(byPath(list))
+		pkgs[0].SetImports(list)
+	}
+
+	for _, pkg := range pkgs {
+		if pkg.Complete() {
+			continue
+		}
+
+		names := make([]string, 0, len(p.pkgIndex[pkg]))
+		for name := range p.pkgIndex[pkg] {
+			names = append(names, name)
+		}
+		sort.Strings(names)
+		for _, name := range names {
+			p.doDecl(pkg, name)
+		}
+
+		// package was imported completely and without errors
+		pkg.MarkComplete()
+	}
+
+	// SetConstraint can't be called if the constraint type is not yet complete.
+	// When type params are created in the 'P' case of (*importReader).obj(),
+	// the associated constraint type may not be complete due to recursion.
+	// Therefore, we defer calling SetConstraint there, and call it here instead
+	// after all types are complete.
+	for _, d := range p.later {
+		typeparams.SetTypeParamConstraint(d.t, d.constraint)
+	}
+
+	for _, typ := range p.interfaceList {
+		typ.Complete()
+	}
+
+	return pkgs, nil
+}
+
+type setConstraintArgs struct {
+	t          *typeparams.TypeParam
+	constraint types.Type
+}
+
+type iimporter struct {
+	version int
+	ipath   string
+
+	localpkg *types.Package
+	insert   func(pkg *types.Package, name string) // "shallow" mode only
+
+	stringData  []byte
+	stringCache map[uint64]string
+	pkgCache    map[uint64]*types.Package
+
+	declData    []byte
+	pkgIndex    map[*types.Package]map[string]uint64
+	typCache    map[uint64]types.Type
+	tparamIndex map[ident]types.Type
+
+	fake          fakeFileSet
+	interfaceList []*types.Interface
+
+	// Arguments for calls to SetConstraint that are deferred due to recursive types
+	later []setConstraintArgs
+
+	indent int // for tracing support
+}
+
+func (p *iimporter) trace(format string, args ...interface{}) {
+	if !trace {
+		// Call sites should also be guarded, but having this check here allows
+		// easily enabling/disabling debug trace statements.
+		return
+	}
+	fmt.Printf(strings.Repeat("..", p.indent)+format+"\n", args...)
+}
+
+func (p *iimporter) doDecl(pkg *types.Package, name string) {
+	if debug {
+		p.trace("import decl %s", name)
+		p.indent++
+		defer func() {
+			p.indent--
+			p.trace("=> %s", name)
+		}()
+	}
+	// See if we've already imported this declaration.
+	if obj := pkg.Scope().Lookup(name); obj != nil {
+		return
+	}
+
+	off, ok := p.pkgIndex[pkg][name]
+	if !ok {
+		// In "shallow" mode, call back to the application to
+		// find the object and insert it into the package scope.
+		if p.insert != nil {
+			assert(pkg != p.localpkg)
+			p.insert(pkg, name) // "can't fail"
+			return
+		}
+		errorf("%v.%v not in index", pkg, name)
+	}
+
+	r := &importReader{p: p, currPkg: pkg}
+	r.declReader.Reset(p.declData[off:])
+
+	r.obj(name)
+}
+
+func (p *iimporter) stringAt(off uint64) string {
+	if s, ok := p.stringCache[off]; ok {
+		return s
+	}
+
+	slen, n := binary.Uvarint(p.stringData[off:])
+	if n <= 0 {
+		errorf("varint failed")
+	}
+	spos := off + uint64(n)
+	s := string(p.stringData[spos : spos+slen])
+	p.stringCache[off] = s
+	return s
+}
+
+func (p *iimporter) pkgAt(off uint64) *types.Package {
+	if pkg, ok := p.pkgCache[off]; ok {
+		return pkg
+	}
+	path := p.stringAt(off)
+	errorf("missing package %q in %q", path, p.ipath)
+	return nil
+}
+
+func (p *iimporter) typAt(off uint64, base *types.Named) types.Type {
+	if t, ok := p.typCache[off]; ok && canReuse(base, t) {
+		return t
+	}
+
+	if off < predeclReserved {
+		errorf("predeclared type missing from cache: %v", off)
+	}
+
+	r := &importReader{p: p}
+	r.declReader.Reset(p.declData[off-predeclReserved:])
+	t := r.doType(base)
+
+	if canReuse(base, t) {
+		p.typCache[off] = t
+	}
+	return t
+}
+
+// canReuse reports whether the type rhs on the RHS of the declaration for def
+// may be re-used.
+//
+// Specifically, if def is non-nil and rhs is an interface type with methods, it
+// may not be re-used because we have a convention of setting the receiver type
+// for interface methods to def.
+func canReuse(def *types.Named, rhs types.Type) bool {
+	if def == nil {
+		return true
+	}
+	iface, _ := rhs.(*types.Interface)
+	if iface == nil {
+		return true
+	}
+	// Don't use iface.Empty() here as iface may not be complete.
+	return iface.NumEmbeddeds() == 0 && iface.NumExplicitMethods() == 0
+}
+
+type importReader struct {
+	p          *iimporter
+	declReader bytes.Reader
+	currPkg    *types.Package
+	prevFile   string
+	prevLine   int64
+	prevColumn int64
+}
+
+func (r *importReader) obj(name string) {
+	tag := r.byte()
+	pos := r.pos()
+
+	switch tag {
+	case 'A':
+		typ := r.typ()
+
+		r.declare(types.NewTypeName(pos, r.currPkg, name, typ))
+
+	case 'C':
+		typ, val := r.value()
+
+		r.declare(types.NewConst(pos, r.currPkg, name, typ, val))
+
+	case 'F', 'G':
+		var tparams []*typeparams.TypeParam
+		if tag == 'G' {
+			tparams = r.tparamList()
+		}
+		sig := r.signature(nil, nil, tparams)
+		r.declare(types.NewFunc(pos, r.currPkg, name, sig))
+
+	case 'T', 'U':
+		// Types can be recursive. We need to setup a stub
+		// declaration before recursing.
+		obj := types.NewTypeName(pos, r.currPkg, name, nil)
+		named := types.NewNamed(obj, nil, nil)
+		// Declare obj before calling r.tparamList, so the new type name is recognized
+		// if used in the constraint of one of its own typeparams (see #48280).
+		r.declare(obj)
+		if tag == 'U' {
+			tparams := r.tparamList()
+			typeparams.SetForNamed(named, tparams)
+		}
+
+		underlying := r.p.typAt(r.uint64(), named).Underlying()
+		named.SetUnderlying(underlying)
+
+		if !isInterface(underlying) {
+			for n := r.uint64(); n > 0; n-- {
+				mpos := r.pos()
+				mname := r.ident()
+				recv := r.param()
+
+				// If the receiver has any targs, set those as the
+				// rparams of the method (since those are the
+				// typeparams being used in the method sig/body).
+				base := baseType(recv.Type())
+				assert(base != nil)
+				targs := typeparams.NamedTypeArgs(base)
+				var rparams []*typeparams.TypeParam
+				if targs.Len() > 0 {
+					rparams = make([]*typeparams.TypeParam, targs.Len())
+					for i := range rparams {
+						rparams[i] = targs.At(i).(*typeparams.TypeParam)
+					}
+				}
+				msig := r.signature(recv, rparams, nil)
+
+				named.AddMethod(types.NewFunc(mpos, r.currPkg, mname, msig))
+			}
+		}
+
+	case 'P':
+		// We need to "declare" a typeparam in order to have a name that
+		// can be referenced recursively (if needed) in the type param's
+		// bound.
+		if r.p.version < iexportVersionGenerics {
+			errorf("unexpected type param type")
+		}
+		name0 := tparamName(name)
+		tn := types.NewTypeName(pos, r.currPkg, name0, nil)
+		t := typeparams.NewTypeParam(tn, nil)
+
+		// To handle recursive references to the typeparam within its
+		// bound, save the partial type in tparamIndex before reading the bounds.
+		id := ident{r.currPkg, name}
+		r.p.tparamIndex[id] = t
+		var implicit bool
+		if r.p.version >= iexportVersionGo1_18 {
+			implicit = r.bool()
+		}
+		constraint := r.typ()
+		if implicit {
+			iface, _ := constraint.(*types.Interface)
+			if iface == nil {
+				errorf("non-interface constraint marked implicit")
+			}
+			typeparams.MarkImplicit(iface)
+		}
+		// The constraint type may not be complete, if we
+		// are in the middle of a type recursion involving type
+		// constraints. So, we defer SetConstraint until we have
+		// completely set up all types in ImportData.
+		r.p.later = append(r.p.later, setConstraintArgs{t: t, constraint: constraint})
+
+	case 'V':
+		typ := r.typ()
+
+		r.declare(types.NewVar(pos, r.currPkg, name, typ))
+
+	default:
+		errorf("unexpected tag: %v", tag)
+	}
+}
+
+func (r *importReader) declare(obj types.Object) {
+	obj.Pkg().Scope().Insert(obj)
+}
+
+func (r *importReader) value() (typ types.Type, val constant.Value) {
+	typ = r.typ()
+	if r.p.version >= iexportVersionGo1_18 {
+		// TODO: add support for using the kind.
+		_ = constant.Kind(r.int64())
+	}
+
+	switch b := typ.Underlying().(*types.Basic); b.Info() & types.IsConstType {
+	case types.IsBoolean:
+		val = constant.MakeBool(r.bool())
+
+	case types.IsString:
+		val = constant.MakeString(r.string())
+
+	case types.IsInteger:
+		var x big.Int
+		r.mpint(&x, b)
+		val = constant.Make(&x)
+
+	case types.IsFloat:
+		val = r.mpfloat(b)
+
+	case types.IsComplex:
+		re := r.mpfloat(b)
+		im := r.mpfloat(b)
+		val = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
+
+	default:
+		if b.Kind() == types.Invalid {
+			val = constant.MakeUnknown()
+			return
+		}
+		errorf("unexpected type %v", typ) // panics
+		panic("unreachable")
+	}
+
+	return
+}
+
+func intSize(b *types.Basic) (signed bool, maxBytes uint) {
+	if (b.Info() & types.IsUntyped) != 0 {
+		return true, 64
+	}
+
+	switch b.Kind() {
+	case types.Float32, types.Complex64:
+		return true, 3
+	case types.Float64, types.Complex128:
+		return true, 7
+	}
+
+	signed = (b.Info() & types.IsUnsigned) == 0
+	switch b.Kind() {
+	case types.Int8, types.Uint8:
+		maxBytes = 1
+	case types.Int16, types.Uint16:
+		maxBytes = 2
+	case types.Int32, types.Uint32:
+		maxBytes = 4
+	default:
+		maxBytes = 8
+	}
+
+	return
+}
+
+func (r *importReader) mpint(x *big.Int, typ *types.Basic) {
+	signed, maxBytes := intSize(typ)
+
+	maxSmall := 256 - maxBytes
+	if signed {
+		maxSmall = 256 - 2*maxBytes
+	}
+	if maxBytes == 1 {
+		maxSmall = 256
+	}
+
+	n, _ := r.declReader.ReadByte()
+	if uint(n) < maxSmall {
+		v := int64(n)
+		if signed {
+			v >>= 1
+			if n&1 != 0 {
+				v = ^v
+			}
+		}
+		x.SetInt64(v)
+		return
+	}
+
+	v := -n
+	if signed {
+		v = -(n &^ 1) >> 1
+	}
+	if v < 1 || uint(v) > maxBytes {
+		errorf("weird decoding: %v, %v => %v", n, signed, v)
+	}
+	b := make([]byte, v)
+	io.ReadFull(&r.declReader, b)
+	x.SetBytes(b)
+	if signed && n&1 != 0 {
+		x.Neg(x)
+	}
+}
+
+func (r *importReader) mpfloat(typ *types.Basic) constant.Value {
+	var mant big.Int
+	r.mpint(&mant, typ)
+	var f big.Float
+	f.SetInt(&mant)
+	if f.Sign() != 0 {
+		f.SetMantExp(&f, int(r.int64()))
+	}
+	return constant.Make(&f)
+}
+
+func (r *importReader) ident() string {
+	return r.string()
+}
+
+func (r *importReader) qualifiedIdent() (*types.Package, string) {
+	name := r.string()
+	pkg := r.pkg()
+	return pkg, name
+}
+
+func (r *importReader) pos() token.Pos {
+	if r.p.version >= iexportVersionPosCol {
+		r.posv1()
+	} else {
+		r.posv0()
+	}
+
+	if r.prevFile == "" && r.prevLine == 0 && r.prevColumn == 0 {
+		return token.NoPos
+	}
+	return r.p.fake.pos(r.prevFile, int(r.prevLine), int(r.prevColumn))
+}
+
+func (r *importReader) posv0() {
+	delta := r.int64()
+	if delta != deltaNewFile {
+		r.prevLine += delta
+	} else if l := r.int64(); l == -1 {
+		r.prevLine += deltaNewFile
+	} else {
+		r.prevFile = r.string()
+		r.prevLine = l
+	}
+}
+
+func (r *importReader) posv1() {
+	delta := r.int64()
+	r.prevColumn += delta >> 1
+	if delta&1 != 0 {
+		delta = r.int64()
+		r.prevLine += delta >> 1
+		if delta&1 != 0 {
+			r.prevFile = r.string()
+		}
+	}
+}
+
+func (r *importReader) typ() types.Type {
+	return r.p.typAt(r.uint64(), nil)
+}
+
+func isInterface(t types.Type) bool {
+	_, ok := t.(*types.Interface)
+	return ok
+}
+
+func (r *importReader) pkg() *types.Package { return r.p.pkgAt(r.uint64()) }
+func (r *importReader) string() string      { return r.p.stringAt(r.uint64()) }
+
+func (r *importReader) doType(base *types.Named) (res types.Type) {
+	k := r.kind()
+	if debug {
+		r.p.trace("importing type %d (base: %s)", k, base)
+		r.p.indent++
+		defer func() {
+			r.p.indent--
+			r.p.trace("=> %s", res)
+		}()
+	}
+	switch k {
+	default:
+		errorf("unexpected kind tag in %q: %v", r.p.ipath, k)
+		return nil
+
+	case definedType:
+		pkg, name := r.qualifiedIdent()
+		r.p.doDecl(pkg, name)
+		return pkg.Scope().Lookup(name).(*types.TypeName).Type()
+	case pointerType:
+		return types.NewPointer(r.typ())
+	case sliceType:
+		return types.NewSlice(r.typ())
+	case arrayType:
+		n := r.uint64()
+		return types.NewArray(r.typ(), int64(n))
+	case chanType:
+		dir := chanDir(int(r.uint64()))
+		return types.NewChan(dir, r.typ())
+	case mapType:
+		return types.NewMap(r.typ(), r.typ())
+	case signatureType:
+		r.currPkg = r.pkg()
+		return r.signature(nil, nil, nil)
+
+	case structType:
+		r.currPkg = r.pkg()
+
+		fields := make([]*types.Var, r.uint64())
+		tags := make([]string, len(fields))
+		for i := range fields {
+			fpos := r.pos()
+			fname := r.ident()
+			ftyp := r.typ()
+			emb := r.bool()
+			tag := r.string()
+
+			fields[i] = types.NewField(fpos, r.currPkg, fname, ftyp, emb)
+			tags[i] = tag
+		}
+		return types.NewStruct(fields, tags)
+
+	case interfaceType:
+		r.currPkg = r.pkg()
+
+		embeddeds := make([]types.Type, r.uint64())
+		for i := range embeddeds {
+			_ = r.pos()
+			embeddeds[i] = r.typ()
+		}
+
+		methods := make([]*types.Func, r.uint64())
+		for i := range methods {
+			mpos := r.pos()
+			mname := r.ident()
+
+			// TODO(mdempsky): Matches bimport.go, but I
+			// don't agree with this.
+			var recv *types.Var
+			if base != nil {
+				recv = types.NewVar(token.NoPos, r.currPkg, "", base)
+			}
+
+			msig := r.signature(recv, nil, nil)
+			methods[i] = types.NewFunc(mpos, r.currPkg, mname, msig)
+		}
+
+		typ := newInterface(methods, embeddeds)
+		r.p.interfaceList = append(r.p.interfaceList, typ)
+		return typ
+
+	case typeParamType:
+		if r.p.version < iexportVersionGenerics {
+			errorf("unexpected type param type")
+		}
+		pkg, name := r.qualifiedIdent()
+		id := ident{pkg, name}
+		if t, ok := r.p.tparamIndex[id]; ok {
+			// We're already in the process of importing this typeparam.
+			return t
+		}
+		// Otherwise, import the definition of the typeparam now.
+		r.p.doDecl(pkg, name)
+		return r.p.tparamIndex[id]
+
+	case instanceType:
+		if r.p.version < iexportVersionGenerics {
+			errorf("unexpected instantiation type")
+		}
+		// pos does not matter for instances: they are positioned on the original
+		// type.
+		_ = r.pos()
+		len := r.uint64()
+		targs := make([]types.Type, len)
+		for i := range targs {
+			targs[i] = r.typ()
+		}
+		baseType := r.typ()
+		// The imported instantiated type doesn't include any methods, so
+		// we must always use the methods of the base (orig) type.
+		// TODO provide a non-nil *Environment
+		t, _ := typeparams.Instantiate(nil, baseType, targs, false)
+		return t
+
+	case unionType:
+		if r.p.version < iexportVersionGenerics {
+			errorf("unexpected instantiation type")
+		}
+		terms := make([]*typeparams.Term, r.uint64())
+		for i := range terms {
+			terms[i] = typeparams.NewTerm(r.bool(), r.typ())
+		}
+		return typeparams.NewUnion(terms)
+	}
+}
+
+func (r *importReader) kind() itag {
+	return itag(r.uint64())
+}
+
+func (r *importReader) signature(recv *types.Var, rparams []*typeparams.TypeParam, tparams []*typeparams.TypeParam) *types.Signature {
+	params := r.paramList()
+	results := r.paramList()
+	variadic := params.Len() > 0 && r.bool()
+	return typeparams.NewSignatureType(recv, rparams, tparams, params, results, variadic)
+}
+
+func (r *importReader) tparamList() []*typeparams.TypeParam {
+	n := r.uint64()
+	if n == 0 {
+		return nil
+	}
+	xs := make([]*typeparams.TypeParam, n)
+	for i := range xs {
+		// Note: the standard library importer is tolerant of nil types here,
+		// though would panic in SetTypeParams.
+		xs[i] = r.typ().(*typeparams.TypeParam)
+	}
+	return xs
+}
+
+func (r *importReader) paramList() *types.Tuple {
+	xs := make([]*types.Var, r.uint64())
+	for i := range xs {
+		xs[i] = r.param()
+	}
+	return types.NewTuple(xs...)
+}
+
+func (r *importReader) param() *types.Var {
+	pos := r.pos()
+	name := r.ident()
+	typ := r.typ()
+	return types.NewParam(pos, r.currPkg, name, typ)
+}
+
+func (r *importReader) bool() bool {
+	return r.uint64() != 0
+}
+
+func (r *importReader) int64() int64 {
+	n, err := binary.ReadVarint(&r.declReader)
+	if err != nil {
+		errorf("readVarint: %v", err)
+	}
+	return n
+}
+
+func (r *importReader) uint64() uint64 {
+	n, err := binary.ReadUvarint(&r.declReader)
+	if err != nil {
+		errorf("readUvarint: %v", err)
+	}
+	return n
+}
+
+func (r *importReader) byte() byte {
+	x, err := r.declReader.ReadByte()
+	if err != nil {
+		errorf("declReader.ReadByte: %v", err)
+	}
+	return x
+}
+
+func baseType(typ types.Type) *types.Named {
+	// pointer receivers are never types.Named types
+	if p, _ := typ.(*types.Pointer); p != nil {
+		typ = p.Elem()
+	}
+	// receiver base types are always (possibly generic) types.Named types
+	n, _ := typ.(*types.Named)
+	return n
+}

vendor/golang.org/x/tools/internal/gcimporter/newInterface10.go

@@ -0,0 +1,22 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.11
+// +build !go1.11
+
+package gcimporter
+
+import "go/types"
+
+func newInterface(methods []*types.Func, embeddeds []types.Type) *types.Interface {
+	named := make([]*types.Named, len(embeddeds))
+	for i, e := range embeddeds {
+		var ok bool
+		named[i], ok = e.(*types.Named)
+		if !ok {
+			panic("embedding of non-defined interfaces in interfaces is not supported before Go 1.11")
+		}
+	}
+	return types.NewInterface(methods, named)
+}

vendor/golang.org/x/tools/internal/gcimporter/newInterface11.go

@@ -0,0 +1,14 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.11
+// +build go1.11
+
+package gcimporter
+
+import "go/types"
+
+func newInterface(methods []*types.Func, embeddeds []types.Type) *types.Interface {
+	return types.NewInterfaceType(methods, embeddeds)
+}

vendor/golang.org/x/tools/internal/gcimporter/support_go117.go

@@ -0,0 +1,16 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.18
+// +build !go1.18
+
+package gcimporter
+
+import "go/types"
+
+const iexportVersion = iexportVersionGo1_11
+
+func additionalPredeclared() []types.Type {
+	return nil
+}

vendor/golang.org/x/tools/internal/gcimporter/support_go118.go

@@ -0,0 +1,37 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.18
+// +build go1.18
+
+package gcimporter
+
+import "go/types"
+
+const iexportVersion = iexportVersionGenerics
+
+// additionalPredeclared returns additional predeclared types in go.1.18.
+func additionalPredeclared() []types.Type {
+	return []types.Type{
+		// comparable
+		types.Universe.Lookup("comparable").Type(),
+
+		// any
+		types.Universe.Lookup("any").Type(),
+	}
+}
+
+// See cmd/compile/internal/types.SplitVargenSuffix.
+func splitVargenSuffix(name string) (base, suffix string) {
+	i := len(name)
+	for i > 0 && name[i-1] >= '0' && name[i-1] <= '9' {
+		i--
+	}
+	const dot = "·"
+	if i >= len(dot) && name[i-len(dot):i] == dot {
+		i -= len(dot)
+		return name[:i], name[i:]
+	}
+	return name, ""
+}

vendor/golang.org/x/tools/internal/gcimporter/unified_no.go

@@ -0,0 +1,10 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !(go1.18 && goexperiment.unified)
+// +build !go1.18 !goexperiment.unified
+
+package gcimporter
+
+const unifiedIR = false

vendor/golang.org/x/tools/internal/gcimporter/unified_yes.go

@@ -0,0 +1,10 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.18 && goexperiment.unified
+// +build go1.18,goexperiment.unified
+
+package gcimporter
+
+const unifiedIR = true

vendor/golang.org/x/tools/internal/gcimporter/ureader_no.go

@@ -0,0 +1,19 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.18
+// +build !go1.18
+
+package gcimporter
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+)
+
+func UImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (_ int, pkg *types.Package, err error) {
+	err = fmt.Errorf("go/tools compiled with a Go version earlier than 1.18 cannot read unified IR export data")
+	return
+}

vendor/golang.org/x/tools/internal/gcimporter/ureader_yes.go

@@ -0,0 +1,698 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Derived from go/internal/gcimporter/ureader.go
+
+//go:build go1.18
+// +build go1.18
+
+package gcimporter
+
+import (
+	"go/token"
+	"go/types"
+	"strings"
+
+	"golang.org/x/tools/internal/pkgbits"
+)
+
+// A pkgReader holds the shared state for reading a unified IR package
+// description.
+type pkgReader struct {
+	pkgbits.PkgDecoder
+
+	fake fakeFileSet
+
+	ctxt    *types.Context
+	imports map[string]*types.Package // previously imported packages, indexed by path
+
+	// lazily initialized arrays corresponding to the unified IR
+	// PosBase, Pkg, and Type sections, respectively.
+	posBases []string // position bases (i.e., file names)
+	pkgs     []*types.Package
+	typs     []types.Type
+
+	// laterFns holds functions that need to be invoked at the end of
+	// import reading.
+	laterFns []func()
+	// laterFors is used in case of 'type A B' to ensure that B is processed before A.
+	laterFors map[types.Type]int
+
+	// ifaces holds a list of constructed Interfaces, which need to have
+	// Complete called after importing is done.
+	ifaces []*types.Interface
+}
+
+// later adds a function to be invoked at the end of import reading.
+func (pr *pkgReader) later(fn func()) {
+	pr.laterFns = append(pr.laterFns, fn)
+}
+
+// See cmd/compile/internal/noder.derivedInfo.
+type derivedInfo struct {
+	idx    pkgbits.Index
+	needed bool
+}
+
+// See cmd/compile/internal/noder.typeInfo.
+type typeInfo struct {
+	idx     pkgbits.Index
+	derived bool
+}
+
+func UImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (_ int, pkg *types.Package, err error) {
+	s := string(data)
+	s = s[:strings.LastIndex(s, "\n$$\n")]
+	input := pkgbits.NewPkgDecoder(path, s)
+	pkg = readUnifiedPackage(fset, nil, imports, input)
+	return
+}
+
+// laterFor adds a function to be invoked at the end of import reading, and records the type that function is finishing.
+func (pr *pkgReader) laterFor(t types.Type, fn func()) {
+	if pr.laterFors == nil {
+		pr.laterFors = make(map[types.Type]int)
+	}
+	pr.laterFors[t] = len(pr.laterFns)
+	pr.laterFns = append(pr.laterFns, fn)
+}
+
+// readUnifiedPackage reads a package description from the given
+// unified IR export data decoder.
+func readUnifiedPackage(fset *token.FileSet, ctxt *types.Context, imports map[string]*types.Package, input pkgbits.PkgDecoder) *types.Package {
+	pr := pkgReader{
+		PkgDecoder: input,
+
+		fake: fakeFileSet{
+			fset:  fset,
+			files: make(map[string]*fileInfo),
+		},
+
+		ctxt:    ctxt,
+		imports: imports,
+
+		posBases: make([]string, input.NumElems(pkgbits.RelocPosBase)),
+		pkgs:     make([]*types.Package, input.NumElems(pkgbits.RelocPkg)),
+		typs:     make([]types.Type, input.NumElems(pkgbits.RelocType)),
+	}
+	defer pr.fake.setLines()
+
+	r := pr.newReader(pkgbits.RelocMeta, pkgbits.PublicRootIdx, pkgbits.SyncPublic)
+	pkg := r.pkg()
+	r.Bool() // has init
+
+	for i, n := 0, r.Len(); i < n; i++ {
+		// As if r.obj(), but avoiding the Scope.Lookup call,
+		// to avoid eager loading of imports.
+		r.Sync(pkgbits.SyncObject)
+		assert(!r.Bool())
+		r.p.objIdx(r.Reloc(pkgbits.RelocObj))
+		assert(r.Len() == 0)
+	}
+
+	r.Sync(pkgbits.SyncEOF)
+
+	for _, fn := range pr.laterFns {
+		fn()
+	}
+
+	for _, iface := range pr.ifaces {
+		iface.Complete()
+	}
+
+	pkg.MarkComplete()
+	return pkg
+}
+
+// A reader holds the state for reading a single unified IR element
+// within a package.
+type reader struct {
+	pkgbits.Decoder
+
+	p *pkgReader
+
+	dict *readerDict
+}
+
+// A readerDict holds the state for type parameters that parameterize
+// the current unified IR element.
+type readerDict struct {
+	// bounds is a slice of typeInfos corresponding to the underlying
+	// bounds of the element's type parameters.
+	bounds []typeInfo
+
+	// tparams is a slice of the constructed TypeParams for the element.
+	tparams []*types.TypeParam
+
+	// devived is a slice of types derived from tparams, which may be
+	// instantiated while reading the current element.
+	derived      []derivedInfo
+	derivedTypes []types.Type // lazily instantiated from derived
+}
+
+func (pr *pkgReader) newReader(k pkgbits.RelocKind, idx pkgbits.Index, marker pkgbits.SyncMarker) *reader {
+	return &reader{
+		Decoder: pr.NewDecoder(k, idx, marker),
+		p:       pr,
+	}
+}
+
+// @@@ Positions
+
+func (r *reader) pos() token.Pos {
+	r.Sync(pkgbits.SyncPos)
+	if !r.Bool() {
+		return token.NoPos
+	}
+
+	// TODO(mdempsky): Delta encoding.
+	posBase := r.posBase()
+	line := r.Uint()
+	col := r.Uint()
+	return r.p.fake.pos(posBase, int(line), int(col))
+}
+
+func (r *reader) posBase() string {
+	return r.p.posBaseIdx(r.Reloc(pkgbits.RelocPosBase))
+}
+
+func (pr *pkgReader) posBaseIdx(idx pkgbits.Index) string {
+	if b := pr.posBases[idx]; b != "" {
+		return b
+	}
+
+	r := pr.newReader(pkgbits.RelocPosBase, idx, pkgbits.SyncPosBase)
+
+	// Within types2, position bases have a lot more details (e.g.,
+	// keeping track of where //line directives appeared exactly).
+	//
+	// For go/types, we just track the file name.
+
+	filename := r.String()
+
+	if r.Bool() { // file base
+		// Was: "b = token.NewTrimmedFileBase(filename, true)"
+	} else { // line base
+		pos := r.pos()
+		line := r.Uint()
+		col := r.Uint()
+
+		// Was: "b = token.NewLineBase(pos, filename, true, line, col)"
+		_, _, _ = pos, line, col
+	}
+
+	b := filename
+	pr.posBases[idx] = b
+	return b
+}
+
+// @@@ Packages
+
+func (r *reader) pkg() *types.Package {
+	r.Sync(pkgbits.SyncPkg)
+	return r.p.pkgIdx(r.Reloc(pkgbits.RelocPkg))
+}
+
+func (pr *pkgReader) pkgIdx(idx pkgbits.Index) *types.Package {
+	// TODO(mdempsky): Consider using some non-nil pointer to indicate
+	// the universe scope, so we don't need to keep re-reading it.
+	if pkg := pr.pkgs[idx]; pkg != nil {
+		return pkg
+	}
+
+	pkg := pr.newReader(pkgbits.RelocPkg, idx, pkgbits.SyncPkgDef).doPkg()
+	pr.pkgs[idx] = pkg
+	return pkg
+}
+
+func (r *reader) doPkg() *types.Package {
+	path := r.String()
+	switch path {
+	case "":
+		path = r.p.PkgPath()
+	case "builtin":
+		return nil // universe
+	case "unsafe":
+		return types.Unsafe
+	}
+
+	if pkg := r.p.imports[path]; pkg != nil {
+		return pkg
+	}
+
+	name := r.String()
+
+	pkg := types.NewPackage(path, name)
+	r.p.imports[path] = pkg
+
+	imports := make([]*types.Package, r.Len())
+	for i := range imports {
+		imports[i] = r.pkg()
+	}
+	pkg.SetImports(flattenImports(imports))
+
+	return pkg
+}
+
+// flattenImports returns the transitive closure of all imported
+// packages rooted from pkgs.
+func flattenImports(pkgs []*types.Package) []*types.Package {
+	var res []*types.Package
+
+	seen := make(map[*types.Package]bool)
+	var add func(pkg *types.Package)
+	add = func(pkg *types.Package) {
+		if seen[pkg] {
+			return
+		}
+		seen[pkg] = true
+		res = append(res, pkg)
+		for _, imp := range pkg.Imports() {
+			add(imp)
+		}
+	}
+
+	for _, pkg := range pkgs {
+		add(pkg)
+	}
+	return res
+}
+
+// @@@ Types
+
+func (r *reader) typ() types.Type {
+	return r.p.typIdx(r.typInfo(), r.dict)
+}
+
+func (r *reader) typInfo() typeInfo {
+	r.Sync(pkgbits.SyncType)
+	if r.Bool() {
+		return typeInfo{idx: pkgbits.Index(r.Len()), derived: true}
+	}
+	return typeInfo{idx: r.Reloc(pkgbits.RelocType), derived: false}
+}
+
+func (pr *pkgReader) typIdx(info typeInfo, dict *readerDict) types.Type {
+	idx := info.idx
+	var where *types.Type
+	if info.derived {
+		where = &dict.derivedTypes[idx]
+		idx = dict.derived[idx].idx
+	} else {
+		where = &pr.typs[idx]
+	}
+
+	if typ := *where; typ != nil {
+		return typ
+	}
+
+	r := pr.newReader(pkgbits.RelocType, idx, pkgbits.SyncTypeIdx)
+	r.dict = dict
+
+	typ := r.doTyp()
+	assert(typ != nil)
+
+	// See comment in pkgReader.typIdx explaining how this happens.
+	if prev := *where; prev != nil {
+		return prev
+	}
+
+	*where = typ
+	return typ
+}
+
+func (r *reader) doTyp() (res types.Type) {
+	switch tag := pkgbits.CodeType(r.Code(pkgbits.SyncType)); tag {
+	default:
+		errorf("unhandled type tag: %v", tag)
+		panic("unreachable")
+
+	case pkgbits.TypeBasic:
+		return types.Typ[r.Len()]
+
+	case pkgbits.TypeNamed:
+		obj, targs := r.obj()
+		name := obj.(*types.TypeName)
+		if len(targs) != 0 {
+			t, _ := types.Instantiate(r.p.ctxt, name.Type(), targs, false)
+			return t
+		}
+		return name.Type()
+
+	case pkgbits.TypeTypeParam:
+		return r.dict.tparams[r.Len()]
+
+	case pkgbits.TypeArray:
+		len := int64(r.Uint64())
+		return types.NewArray(r.typ(), len)
+	case pkgbits.TypeChan:
+		dir := types.ChanDir(r.Len())
+		return types.NewChan(dir, r.typ())
+	case pkgbits.TypeMap:
+		return types.NewMap(r.typ(), r.typ())
+	case pkgbits.TypePointer:
+		return types.NewPointer(r.typ())
+	case pkgbits.TypeSignature:
+		return r.signature(nil, nil, nil)
+	case pkgbits.TypeSlice:
+		return types.NewSlice(r.typ())
+	case pkgbits.TypeStruct:
+		return r.structType()
+	case pkgbits.TypeInterface:
+		return r.interfaceType()
+	case pkgbits.TypeUnion:
+		return r.unionType()
+	}
+}
+
+func (r *reader) structType() *types.Struct {
+	fields := make([]*types.Var, r.Len())
+	var tags []string
+	for i := range fields {
+		pos := r.pos()
+		pkg, name := r.selector()
+		ftyp := r.typ()
+		tag := r.String()
+		embedded := r.Bool()
+
+		fields[i] = types.NewField(pos, pkg, name, ftyp, embedded)
+		if tag != "" {
+			for len(tags) < i {
+				tags = append(tags, "")
+			}
+			tags = append(tags, tag)
+		}
+	}
+	return types.NewStruct(fields, tags)
+}
+
+func (r *reader) unionType() *types.Union {
+	terms := make([]*types.Term, r.Len())
+	for i := range terms {
+		terms[i] = types.NewTerm(r.Bool(), r.typ())
+	}
+	return types.NewUnion(terms)
+}
+
+func (r *reader) interfaceType() *types.Interface {
+	methods := make([]*types.Func, r.Len())
+	embeddeds := make([]types.Type, r.Len())
+	implicit := len(methods) == 0 && len(embeddeds) == 1 && r.Bool()
+
+	for i := range methods {
+		pos := r.pos()
+		pkg, name := r.selector()
+		mtyp := r.signature(nil, nil, nil)
+		methods[i] = types.NewFunc(pos, pkg, name, mtyp)
+	}
+
+	for i := range embeddeds {
+		embeddeds[i] = r.typ()
+	}
+
+	iface := types.NewInterfaceType(methods, embeddeds)
+	if implicit {
+		iface.MarkImplicit()
+	}
+
+	// We need to call iface.Complete(), but if there are any embedded
+	// defined types, then we may not have set their underlying
+	// interface type yet. So we need to defer calling Complete until
+	// after we've called SetUnderlying everywhere.
+	//
+	// TODO(mdempsky): After CL 424876 lands, it should be safe to call
+	// iface.Complete() immediately.
+	r.p.ifaces = append(r.p.ifaces, iface)
+
+	return iface
+}
+
+func (r *reader) signature(recv *types.Var, rtparams, tparams []*types.TypeParam) *types.Signature {
+	r.Sync(pkgbits.SyncSignature)
+
+	params := r.params()
+	results := r.params()
+	variadic := r.Bool()
+
+	return types.NewSignatureType(recv, rtparams, tparams, params, results, variadic)
+}
+
+func (r *reader) params() *types.Tuple {
+	r.Sync(pkgbits.SyncParams)
+
+	params := make([]*types.Var, r.Len())
+	for i := range params {
+		params[i] = r.param()
+	}
+
+	return types.NewTuple(params...)
+}
+
+func (r *reader) param() *types.Var {
+	r.Sync(pkgbits.SyncParam)
+
+	pos := r.pos()
+	pkg, name := r.localIdent()
+	typ := r.typ()
+
+	return types.NewParam(pos, pkg, name, typ)
+}
+
+// @@@ Objects
+
+func (r *reader) obj() (types.Object, []types.Type) {
+	r.Sync(pkgbits.SyncObject)
+
+	assert(!r.Bool())
+
+	pkg, name := r.p.objIdx(r.Reloc(pkgbits.RelocObj))
+	obj := pkgScope(pkg).Lookup(name)
+
+	targs := make([]types.Type, r.Len())
+	for i := range targs {
+		targs[i] = r.typ()
+	}
+
+	return obj, targs
+}
+
+func (pr *pkgReader) objIdx(idx pkgbits.Index) (*types.Package, string) {
+	rname := pr.newReader(pkgbits.RelocName, idx, pkgbits.SyncObject1)
+
+	objPkg, objName := rname.qualifiedIdent()
+	assert(objName != "")
+
+	tag := pkgbits.CodeObj(rname.Code(pkgbits.SyncCodeObj))
+
+	if tag == pkgbits.ObjStub {
+		assert(objPkg == nil || objPkg == types.Unsafe)
+		return objPkg, objName
+	}
+
+	// Ignore local types promoted to global scope (#55110).
+	if _, suffix := splitVargenSuffix(objName); suffix != "" {
+		return objPkg, objName
+	}
+
+	if objPkg.Scope().Lookup(objName) == nil {
+		dict := pr.objDictIdx(idx)
+
+		r := pr.newReader(pkgbits.RelocObj, idx, pkgbits.SyncObject1)
+		r.dict = dict
+
+		declare := func(obj types.Object) {
+			objPkg.Scope().Insert(obj)
+		}
+
+		switch tag {
+		default:
+			panic("weird")
+
+		case pkgbits.ObjAlias:
+			pos := r.pos()
+			typ := r.typ()
+			declare(types.NewTypeName(pos, objPkg, objName, typ))
+
+		case pkgbits.ObjConst:
+			pos := r.pos()
+			typ := r.typ()
+			val := r.Value()
+			declare(types.NewConst(pos, objPkg, objName, typ, val))
+
+		case pkgbits.ObjFunc:
+			pos := r.pos()
+			tparams := r.typeParamNames()
+			sig := r.signature(nil, nil, tparams)
+			declare(types.NewFunc(pos, objPkg, objName, sig))
+
+		case pkgbits.ObjType:
+			pos := r.pos()
+
+			obj := types.NewTypeName(pos, objPkg, objName, nil)
+			named := types.NewNamed(obj, nil, nil)
+			declare(obj)
+
+			named.SetTypeParams(r.typeParamNames())
+
+			rhs := r.typ()
+			pk := r.p
+			pk.laterFor(named, func() {
+				// First be sure that the rhs is initialized, if it needs to be initialized.
+				delete(pk.laterFors, named) // prevent cycles
+				if i, ok := pk.laterFors[rhs]; ok {
+					f := pk.laterFns[i]
+					pk.laterFns[i] = func() {} // function is running now, so replace it with a no-op
+					f()                        // initialize RHS
+				}
+				underlying := rhs.Underlying()
+
+				// If the underlying type is an interface, we need to
+				// duplicate its methods so we can replace the receiver
+				// parameter's type (#49906).
+				if iface, ok := underlying.(*types.Interface); ok && iface.NumExplicitMethods() != 0 {
+					methods := make([]*types.Func, iface.NumExplicitMethods())
+					for i := range methods {
+						fn := iface.ExplicitMethod(i)
+						sig := fn.Type().(*types.Signature)
+
+						recv := types.NewVar(fn.Pos(), fn.Pkg(), "", named)
+						methods[i] = types.NewFunc(fn.Pos(), fn.Pkg(), fn.Name(), types.NewSignature(recv, sig.Params(), sig.Results(), sig.Variadic()))
+					}
+
+					embeds := make([]types.Type, iface.NumEmbeddeds())
+					for i := range embeds {
+						embeds[i] = iface.EmbeddedType(i)
+					}
+
+					newIface := types.NewInterfaceType(methods, embeds)
+					r.p.ifaces = append(r.p.ifaces, newIface)
+					underlying = newIface
+				}
+
+				named.SetUnderlying(underlying)
+			})
+
+			for i, n := 0, r.Len(); i < n; i++ {
+				named.AddMethod(r.method())
+			}
+
+		case pkgbits.ObjVar:
+			pos := r.pos()
+			typ := r.typ()
+			declare(types.NewVar(pos, objPkg, objName, typ))
+		}
+	}
+
+	return objPkg, objName
+}
+
+func (pr *pkgReader) objDictIdx(idx pkgbits.Index) *readerDict {
+	r := pr.newReader(pkgbits.RelocObjDict, idx, pkgbits.SyncObject1)
+
+	var dict readerDict
+
+	if implicits := r.Len(); implicits != 0 {
+		errorf("unexpected object with %v implicit type parameter(s)", implicits)
+	}
+
+	dict.bounds = make([]typeInfo, r.Len())
+	for i := range dict.bounds {
+		dict.bounds[i] = r.typInfo()
+	}
+
+	dict.derived = make([]derivedInfo, r.Len())
+	dict.derivedTypes = make([]types.Type, len(dict.derived))
+	for i := range dict.derived {
+		dict.derived[i] = derivedInfo{r.Reloc(pkgbits.RelocType), r.Bool()}
+	}
+
+	// function references follow, but reader doesn't need those
+
+	return &dict
+}
+
+func (r *reader) typeParamNames() []*types.TypeParam {
+	r.Sync(pkgbits.SyncTypeParamNames)
+
+	// Note: This code assumes it only processes objects without
+	// implement type parameters. This is currently fine, because
+	// reader is only used to read in exported declarations, which are
+	// always package scoped.
+
+	if len(r.dict.bounds) == 0 {
+		return nil
+	}
+
+	// Careful: Type parameter lists may have cycles. To allow for this,
+	// we construct the type parameter list in two passes: first we
+	// create all the TypeNames and TypeParams, then we construct and
+	// set the bound type.
+
+	r.dict.tparams = make([]*types.TypeParam, len(r.dict.bounds))
+	for i := range r.dict.bounds {
+		pos := r.pos()
+		pkg, name := r.localIdent()
+
+		tname := types.NewTypeName(pos, pkg, name, nil)
+		r.dict.tparams[i] = types.NewTypeParam(tname, nil)
+	}
+
+	typs := make([]types.Type, len(r.dict.bounds))
+	for i, bound := range r.dict.bounds {
+		typs[i] = r.p.typIdx(bound, r.dict)
+	}
+
+	// TODO(mdempsky): This is subtle, elaborate further.
+	//
+	// We have to save tparams outside of the closure, because
+	// typeParamNames() can be called multiple times with the same
+	// dictionary instance.
+	//
+	// Also, this needs to happen later to make sure SetUnderlying has
+	// been called.
+	//
+	// TODO(mdempsky): Is it safe to have a single "later" slice or do
+	// we need to have multiple passes? See comments on CL 386002 and
+	// go.dev/issue/52104.
+	tparams := r.dict.tparams
+	r.p.later(func() {
+		for i, typ := range typs {
+			tparams[i].SetConstraint(typ)
+		}
+	})
+
+	return r.dict.tparams
+}
+
+func (r *reader) method() *types.Func {
+	r.Sync(pkgbits.SyncMethod)
+	pos := r.pos()
+	pkg, name := r.selector()
+
+	rparams := r.typeParamNames()
+	sig := r.signature(r.param(), rparams, nil)
+
+	_ = r.pos() // TODO(mdempsky): Remove; this is a hacker for linker.go.
+	return types.NewFunc(pos, pkg, name, sig)
+}
+
+func (r *reader) qualifiedIdent() (*types.Package, string) { return r.ident(pkgbits.SyncSym) }
+func (r *reader) localIdent() (*types.Package, string)     { return r.ident(pkgbits.SyncLocalIdent) }
+func (r *reader) selector() (*types.Package, string)       { return r.ident(pkgbits.SyncSelector) }
+
+func (r *reader) ident(marker pkgbits.SyncMarker) (*types.Package, string) {
+	r.Sync(marker)
+	return r.pkg(), r.String()
+}
+
+// pkgScope returns pkg.Scope().
+// If pkg is nil, it returns types.Universe instead.
+//
+// TODO(mdempsky): Remove after x/tools can depend on Go 1.19.
+func pkgScope(pkg *types.Package) *types.Scope {
+	if pkg != nil {
+		return pkg.Scope()
+	}
+	return types.Universe
+}

vendor/golang.org/x/tools/internal/gocommand/invoke.go

@@ -0,0 +1,356 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package gocommand is a helper for calling the go command.
+package gocommand
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"regexp"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	exec "golang.org/x/sys/execabs"
+
+	"golang.org/x/tools/internal/event"
+)
+
+// An Runner will run go command invocations and serialize
+// them if it sees a concurrency error.
+type Runner struct {
+	// once guards the runner initialization.
+	once sync.Once
+
+	// inFlight tracks available workers.
+	inFlight chan struct{}
+
+	// serialized guards the ability to run a go command serially,
+	// to avoid deadlocks when claiming workers.
+	serialized chan struct{}
+}
+
+const maxInFlight = 10
+
+func (runner *Runner) initialize() {
+	runner.once.Do(func() {
+		runner.inFlight = make(chan struct{}, maxInFlight)
+		runner.serialized = make(chan struct{}, 1)
+	})
+}
+
+// 1.13: go: updates to go.mod needed, but contents have changed
+// 1.14: go: updating go.mod: existing contents have changed since last read
+var modConcurrencyError = regexp.MustCompile(`go:.*go.mod.*contents have changed`)
+
+// Run is a convenience wrapper around RunRaw.
+// It returns only stdout and a "friendly" error.
+func (runner *Runner) Run(ctx context.Context, inv Invocation) (*bytes.Buffer, error) {
+	stdout, _, friendly, _ := runner.RunRaw(ctx, inv)
+	return stdout, friendly
+}
+
+// RunPiped runs the invocation serially, always waiting for any concurrent
+// invocations to complete first.
+func (runner *Runner) RunPiped(ctx context.Context, inv Invocation, stdout, stderr io.Writer) error {
+	_, err := runner.runPiped(ctx, inv, stdout, stderr)
+	return err
+}
+
+// RunRaw runs the invocation, serializing requests only if they fight over
+// go.mod changes.
+func (runner *Runner) RunRaw(ctx context.Context, inv Invocation) (*bytes.Buffer, *bytes.Buffer, error, error) {
+	// Make sure the runner is always initialized.
+	runner.initialize()
+
+	// First, try to run the go command concurrently.
+	stdout, stderr, friendlyErr, err := runner.runConcurrent(ctx, inv)
+
+	// If we encounter a load concurrency error, we need to retry serially.
+	if friendlyErr == nil || !modConcurrencyError.MatchString(friendlyErr.Error()) {
+		return stdout, stderr, friendlyErr, err
+	}
+	event.Error(ctx, "Load concurrency error, will retry serially", err)
+
+	// Run serially by calling runPiped.
+	stdout.Reset()
+	stderr.Reset()
+	friendlyErr, err = runner.runPiped(ctx, inv, stdout, stderr)
+	return stdout, stderr, friendlyErr, err
+}
+
+func (runner *Runner) runConcurrent(ctx context.Context, inv Invocation) (*bytes.Buffer, *bytes.Buffer, error, error) {
+	// Wait for 1 worker to become available.
+	select {
+	case <-ctx.Done():
+		return nil, nil, nil, ctx.Err()
+	case runner.inFlight <- struct{}{}:
+		defer func() { <-runner.inFlight }()
+	}
+
+	stdout, stderr := &bytes.Buffer{}, &bytes.Buffer{}
+	friendlyErr, err := inv.runWithFriendlyError(ctx, stdout, stderr)
+	return stdout, stderr, friendlyErr, err
+}
+
+func (runner *Runner) runPiped(ctx context.Context, inv Invocation, stdout, stderr io.Writer) (error, error) {
+	// Make sure the runner is always initialized.
+	runner.initialize()
+
+	// Acquire the serialization lock. This avoids deadlocks between two
+	// runPiped commands.
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	case runner.serialized <- struct{}{}:
+		defer func() { <-runner.serialized }()
+	}
+
+	// Wait for all in-progress go commands to return before proceeding,
+	// to avoid load concurrency errors.
+	for i := 0; i < maxInFlight; i++ {
+		select {
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		case runner.inFlight <- struct{}{}:
+			// Make sure we always "return" any workers we took.
+			defer func() { <-runner.inFlight }()
+		}
+	}
+
+	return inv.runWithFriendlyError(ctx, stdout, stderr)
+}
+
+// An Invocation represents a call to the go command.
+type Invocation struct {
+	Verb       string
+	Args       []string
+	BuildFlags []string
+
+	// If ModFlag is set, the go command is invoked with -mod=ModFlag.
+	ModFlag string
+
+	// If ModFile is set, the go command is invoked with -modfile=ModFile.
+	ModFile string
+
+	// If Overlay is set, the go command is invoked with -overlay=Overlay.
+	Overlay string
+
+	// If CleanEnv is set, the invocation will run only with the environment
+	// in Env, not starting with os.Environ.
+	CleanEnv   bool
+	Env        []string
+	WorkingDir string
+	Logf       func(format string, args ...interface{})
+}
+
+func (i *Invocation) runWithFriendlyError(ctx context.Context, stdout, stderr io.Writer) (friendlyError error, rawError error) {
+	rawError = i.run(ctx, stdout, stderr)
+	if rawError != nil {
+		friendlyError = rawError
+		// Check for 'go' executable not being found.
+		if ee, ok := rawError.(*exec.Error); ok && ee.Err == exec.ErrNotFound {
+			friendlyError = fmt.Errorf("go command required, not found: %v", ee)
+		}
+		if ctx.Err() != nil {
+			friendlyError = ctx.Err()
+		}
+		friendlyError = fmt.Errorf("err: %v: stderr: %s", friendlyError, stderr)
+	}
+	return
+}
+
+func (i *Invocation) run(ctx context.Context, stdout, stderr io.Writer) error {
+	log := i.Logf
+	if log == nil {
+		log = func(string, ...interface{}) {}
+	}
+
+	goArgs := []string{i.Verb}
+
+	appendModFile := func() {
+		if i.ModFile != "" {
+			goArgs = append(goArgs, "-modfile="+i.ModFile)
+		}
+	}
+	appendModFlag := func() {
+		if i.ModFlag != "" {
+			goArgs = append(goArgs, "-mod="+i.ModFlag)
+		}
+	}
+	appendOverlayFlag := func() {
+		if i.Overlay != "" {
+			goArgs = append(goArgs, "-overlay="+i.Overlay)
+		}
+	}
+
+	switch i.Verb {
+	case "env", "version":
+		goArgs = append(goArgs, i.Args...)
+	case "mod":
+		// mod needs the sub-verb before flags.
+		goArgs = append(goArgs, i.Args[0])
+		appendModFile()
+		goArgs = append(goArgs, i.Args[1:]...)
+	case "get":
+		goArgs = append(goArgs, i.BuildFlags...)
+		appendModFile()
+		goArgs = append(goArgs, i.Args...)
+
+	default: // notably list and build.
+		goArgs = append(goArgs, i.BuildFlags...)
+		appendModFile()
+		appendModFlag()
+		appendOverlayFlag()
+		goArgs = append(goArgs, i.Args...)
+	}
+	cmd := exec.Command("go", goArgs...)
+	cmd.Stdout = stdout
+	cmd.Stderr = stderr
+	// On darwin the cwd gets resolved to the real path, which breaks anything that
+	// expects the working directory to keep the original path, including the
+	// go command when dealing with modules.
+	// The Go stdlib has a special feature where if the cwd and the PWD are the
+	// same node then it trusts the PWD, so by setting it in the env for the child
+	// process we fix up all the paths returned by the go command.
+	if !i.CleanEnv {
+		cmd.Env = os.Environ()
+	}
+	cmd.Env = append(cmd.Env, i.Env...)
+	if i.WorkingDir != "" {
+		cmd.Env = append(cmd.Env, "PWD="+i.WorkingDir)
+		cmd.Dir = i.WorkingDir
+	}
+	defer func(start time.Time) { log("%s for %v", time.Since(start), cmdDebugStr(cmd)) }(time.Now())
+
+	return runCmdContext(ctx, cmd)
+}
+
+// DebugHangingGoCommands may be set by tests to enable additional
+// instrumentation (including panics) for debugging hanging Go commands.
+//
+// See golang/go#54461 for details.
+var DebugHangingGoCommands = false
+
+// runCmdContext is like exec.CommandContext except it sends os.Interrupt
+// before os.Kill.
+func runCmdContext(ctx context.Context, cmd *exec.Cmd) error {
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+	resChan := make(chan error, 1)
+	go func() {
+		resChan <- cmd.Wait()
+	}()
+
+	// If we're interested in debugging hanging Go commands, stop waiting after a
+	// minute and panic with interesting information.
+	if DebugHangingGoCommands {
+		select {
+		case err := <-resChan:
+			return err
+		case <-time.After(1 * time.Minute):
+			HandleHangingGoCommand(cmd.Process)
+		case <-ctx.Done():
+		}
+	} else {
+		select {
+		case err := <-resChan:
+			return err
+		case <-ctx.Done():
+		}
+	}
+
+	// Cancelled. Interrupt and see if it ends voluntarily.
+	cmd.Process.Signal(os.Interrupt)
+	select {
+	case err := <-resChan:
+		return err
+	case <-time.After(time.Second):
+	}
+
+	// Didn't shut down in response to interrupt. Kill it hard.
+	// TODO(rfindley): per advice from bcmills@, it may be better to send SIGQUIT
+	// on certain platforms, such as unix.
+	if err := cmd.Process.Kill(); err != nil && DebugHangingGoCommands {
+		// Don't panic here as this reliably fails on windows with EINVAL.
+		log.Printf("error killing the Go command: %v", err)
+	}
+
+	// See above: don't wait indefinitely if we're debugging hanging Go commands.
+	if DebugHangingGoCommands {
+		select {
+		case err := <-resChan:
+			return err
+		case <-time.After(10 * time.Second): // a shorter wait as resChan should return quickly following Kill
+			HandleHangingGoCommand(cmd.Process)
+		}
+	}
+	return <-resChan
+}
+
+func HandleHangingGoCommand(proc *os.Process) {
+	switch runtime.GOOS {
+	case "linux", "darwin", "freebsd", "netbsd":
+		fmt.Fprintln(os.Stderr, `DETECTED A HANGING GO COMMAND
+
+The gopls test runner has detected a hanging go command. In order to debug
+this, the output of ps and lsof/fstat is printed below.
+
+See golang/go#54461 for more details.`)
+
+		fmt.Fprintln(os.Stderr, "\nps axo ppid,pid,command:")
+		fmt.Fprintln(os.Stderr, "-------------------------")
+		psCmd := exec.Command("ps", "axo", "ppid,pid,command")
+		psCmd.Stdout = os.Stderr
+		psCmd.Stderr = os.Stderr
+		if err := psCmd.Run(); err != nil {
+			panic(fmt.Sprintf("running ps: %v", err))
+		}
+
+		listFiles := "lsof"
+		if runtime.GOOS == "freebsd" || runtime.GOOS == "netbsd" {
+			listFiles = "fstat"
+		}
+
+		fmt.Fprintln(os.Stderr, "\n"+listFiles+":")
+		fmt.Fprintln(os.Stderr, "-----")
+		listFilesCmd := exec.Command(listFiles)
+		listFilesCmd.Stdout = os.Stderr
+		listFilesCmd.Stderr = os.Stderr
+		if err := listFilesCmd.Run(); err != nil {
+			panic(fmt.Sprintf("running %s: %v", listFiles, err))
+		}
+	}
+	panic(fmt.Sprintf("detected hanging go command (pid %d): see golang/go#54461 for more details", proc.Pid))
+}
+
+func cmdDebugStr(cmd *exec.Cmd) string {
+	env := make(map[string]string)
+	for _, kv := range cmd.Env {
+		split := strings.SplitN(kv, "=", 2)
+		if len(split) == 2 {
+			k, v := split[0], split[1]
+			env[k] = v
+		}
+	}
+
+	var args []string
+	for _, arg := range cmd.Args {
+		quoted := strconv.Quote(arg)
+		if quoted[1:len(quoted)-1] != arg || strings.Contains(arg, " ") {
+			args = append(args, quoted)
+		} else {
+			args = append(args, arg)
+		}
+	}
+	return fmt.Sprintf("GOROOT=%v GOPATH=%v GO111MODULE=%v GOPROXY=%v PWD=%v %v", env["GOROOT"], env["GOPATH"], env["GO111MODULE"], env["GOPROXY"], env["PWD"], strings.Join(args, " "))
+}

vendor/golang.org/x/tools/internal/gocommand/vendor.go

@@ -0,0 +1,109 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gocommand
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"time"
+
+	"golang.org/x/mod/semver"
+)
+
+// ModuleJSON holds information about a module.
+type ModuleJSON struct {
+	Path      string      // module path
+	Version   string      // module version
+	Versions  []string    // available module versions (with -versions)
+	Replace   *ModuleJSON // replaced by this module
+	Time      *time.Time  // time version was created
+	Update    *ModuleJSON // available update, if any (with -u)
+	Main      bool        // is this the main module?
+	Indirect  bool        // is this module only an indirect dependency of main module?
+	Dir       string      // directory holding files for this module, if any
+	GoMod     string      // path to go.mod file used when loading this module, if any
+	GoVersion string      // go version used in module
+}
+
+var modFlagRegexp = regexp.MustCompile(`-mod[ =](\w+)`)
+
+// VendorEnabled reports whether vendoring is enabled. It takes a *Runner to execute Go commands
+// with the supplied context.Context and Invocation. The Invocation can contain pre-defined fields,
+// of which only Verb and Args are modified to run the appropriate Go command.
+// Inspired by setDefaultBuildMod in modload/init.go
+func VendorEnabled(ctx context.Context, inv Invocation, r *Runner) (bool, *ModuleJSON, error) {
+	mainMod, go114, err := getMainModuleAnd114(ctx, inv, r)
+	if err != nil {
+		return false, nil, err
+	}
+
+	// We check the GOFLAGS to see if there is anything overridden or not.
+	inv.Verb = "env"
+	inv.Args = []string{"GOFLAGS"}
+	stdout, err := r.Run(ctx, inv)
+	if err != nil {
+		return false, nil, err
+	}
+	goflags := string(bytes.TrimSpace(stdout.Bytes()))
+	matches := modFlagRegexp.FindStringSubmatch(goflags)
+	var modFlag string
+	if len(matches) != 0 {
+		modFlag = matches[1]
+	}
+	// Don't override an explicit '-mod=' argument.
+	if modFlag == "vendor" {
+		return true, mainMod, nil
+	} else if modFlag != "" {
+		return false, nil, nil
+	}
+	if mainMod == nil || !go114 {
+		return false, nil, nil
+	}
+	// Check 1.14's automatic vendor mode.
+	if fi, err := os.Stat(filepath.Join(mainMod.Dir, "vendor")); err == nil && fi.IsDir() {
+		if mainMod.GoVersion != "" && semver.Compare("v"+mainMod.GoVersion, "v1.14") >= 0 {
+			// The Go version is at least 1.14, and a vendor directory exists.
+			// Set -mod=vendor by default.
+			return true, mainMod, nil
+		}
+	}
+	return false, nil, nil
+}
+
+// getMainModuleAnd114 gets one of the main modules' information and whether the
+// go command in use is 1.14+. This is the information needed to figure out
+// if vendoring should be enabled.
+func getMainModuleAnd114(ctx context.Context, inv Invocation, r *Runner) (*ModuleJSON, bool, error) {
+	const format = `{{.Path}}
+{{.Dir}}
+{{.GoMod}}
+{{.GoVersion}}
+{{range context.ReleaseTags}}{{if eq . "go1.14"}}{{.}}{{end}}{{end}}
+`
+	inv.Verb = "list"
+	inv.Args = []string{"-m", "-f", format}
+	stdout, err := r.Run(ctx, inv)
+	if err != nil {
+		return nil, false, err
+	}
+
+	lines := strings.Split(stdout.String(), "\n")
+	if len(lines) < 5 {
+		return nil, false, fmt.Errorf("unexpected stdout: %q", stdout.String())
+	}
+	mod := &ModuleJSON{
+		Path:      lines[0],
+		Dir:       lines[1],
+		GoMod:     lines[2],
+		GoVersion: lines[3],
+		Main:      true,
+	}
+	return mod, lines[4] == "go1.14", nil
+}

vendor/golang.org/x/tools/internal/gocommand/version.go

@@ -0,0 +1,58 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gocommand
+
+import (
+	"context"
+	"fmt"
+	"strings"
+)
+
+// GoVersion reports the minor version number of the highest release
+// tag built into the go command on the PATH.
+//
+// Note that this may be higher than the version of the go tool used
+// to build this application, and thus the versions of the standard
+// go/{scanner,parser,ast,types} packages that are linked into it.
+// In that case, callers should either downgrade to the version of
+// go used to build the application, or report an error that the
+// application is too old to use the go command on the PATH.
+func GoVersion(ctx context.Context, inv Invocation, r *Runner) (int, error) {
+	inv.Verb = "list"
+	inv.Args = []string{"-e", "-f", `{{context.ReleaseTags}}`, `--`, `unsafe`}
+	inv.Env = append(append([]string{}, inv.Env...), "GO111MODULE=off")
+	// Unset any unneeded flags, and remove them from BuildFlags, if they're
+	// present.
+	inv.ModFile = ""
+	inv.ModFlag = ""
+	var buildFlags []string
+	for _, flag := range inv.BuildFlags {
+		// Flags can be prefixed by one or two dashes.
+		f := strings.TrimPrefix(strings.TrimPrefix(flag, "-"), "-")
+		if strings.HasPrefix(f, "mod=") || strings.HasPrefix(f, "modfile=") {
+			continue
+		}
+		buildFlags = append(buildFlags, flag)
+	}
+	inv.BuildFlags = buildFlags
+	stdoutBytes, err := r.Run(ctx, inv)
+	if err != nil {
+		return 0, err
+	}
+	stdout := stdoutBytes.String()
+	if len(stdout) < 3 {
+		return 0, fmt.Errorf("bad ReleaseTags output: %q", stdout)
+	}
+	// Split up "[go1.1 go1.15]" and return highest go1.X value.
+	tags := strings.Fields(stdout[1 : len(stdout)-2])
+	for i := len(tags) - 1; i >= 0; i-- {
+		var version int
+		if _, err := fmt.Sscanf(tags[i], "go1.%d", &version); err != nil {
+			continue
+		}
+		return version, nil
+	}
+	return 0, fmt.Errorf("no parseable ReleaseTags in %v", tags)
+}

vendor/golang.org/x/tools/internal/goroot/importcfg.go

@@ -0,0 +1,71 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package goroot is a copy of package internal/goroot
+// in the main GO repot. It provides a utility to produce
+// an importcfg and import path to package file map mapping
+// standard library packages to the locations of their export
+// data files.
+package goroot
+
+import (
+	"bytes"
+	"fmt"
+	"os/exec"
+	"strings"
+	"sync"
+)
+
+// Importcfg returns an importcfg file to be passed to the
+// Go compiler that contains the cached paths for the .a files for the
+// standard library.
+func Importcfg() (string, error) {
+	var icfg bytes.Buffer
+
+	m, err := PkgfileMap()
+	if err != nil {
+		return "", err
+	}
+	fmt.Fprintf(&icfg, "# import config")
+	for importPath, export := range m {
+		if importPath != "unsafe" && export != "" { // unsafe
+			fmt.Fprintf(&icfg, "\npackagefile %s=%s", importPath, export)
+		}
+	}
+	s := icfg.String()
+	return s, nil
+}
+
+var (
+	stdlibPkgfileMap map[string]string
+	stdlibPkgfileErr error
+	once             sync.Once
+)
+
+// PkgfileMap returns a map of package paths to the location on disk
+// of the .a file for the package.
+// The caller must not modify the map.
+func PkgfileMap() (map[string]string, error) {
+	once.Do(func() {
+		m := make(map[string]string)
+		output, err := exec.Command("go", "list", "-export", "-e", "-f", "{{.ImportPath}} {{.Export}}", "std", "cmd").Output()
+		if err != nil {
+			stdlibPkgfileErr = err
+		}
+		for _, line := range strings.Split(string(output), "\n") {
+			if line == "" {
+				continue
+			}
+			sp := strings.SplitN(line, " ", 2)
+			if len(sp) != 2 {
+				err = fmt.Errorf("determining pkgfile map: invalid line in go list output: %q", line)
+				return
+			}
+			importPath, export := sp[0], sp[1]
+			m[importPath] = export
+		}
+		stdlibPkgfileMap = m
+	})
+	return stdlibPkgfileMap, stdlibPkgfileErr
+}

vendor/golang.org/x/tools/internal/packagesinternal/packages.go

@@ -0,0 +1,30 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package packagesinternal exposes internal-only fields from go/packages.
+package packagesinternal
+
+import (
+	"golang.org/x/tools/internal/gocommand"
+)
+
+var GetForTest = func(p interface{}) string { return "" }
+var GetDepsErrors = func(p interface{}) []*PackageError { return nil }
+
+type PackageError struct {
+	ImportStack []string // shortest path from package named on command line to this one
+	Pos         string   // position of error (if present, file:line:col)
+	Err         string   // the error itself
+}
+
+var GetGoCmdRunner = func(config interface{}) *gocommand.Runner { return nil }
+
+var SetGoCmdRunner = func(config interface{}, runner *gocommand.Runner) {}
+
+var TypecheckCgo int
+var DepsErrors int // must be set as a LoadMode to call GetDepsErrors
+var ForTest int    // must be set as a LoadMode to call GetForTest
+
+var SetModFlag = func(config interface{}, value string) {}
+var SetModFile = func(config interface{}, value string) {}

vendor/golang.org/x/tools/internal/pkgbits/codes.go

@@ -0,0 +1,77 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pkgbits
+
+// A Code is an enum value that can be encoded into bitstreams.
+//
+// Code types are preferable for enum types, because they allow
+// Decoder to detect desyncs.
+type Code interface {
+	// Marker returns the SyncMarker for the Code's dynamic type.
+	Marker() SyncMarker
+
+	// Value returns the Code's ordinal value.
+	Value() int
+}
+
+// A CodeVal distinguishes among go/constant.Value encodings.
+type CodeVal int
+
+func (c CodeVal) Marker() SyncMarker { return SyncVal }
+func (c CodeVal) Value() int         { return int(c) }
+
+// Note: These values are public and cannot be changed without
+// updating the go/types importers.
+
+const (
+	ValBool CodeVal = iota
+	ValString
+	ValInt64
+	ValBigInt
+	ValBigRat
+	ValBigFloat
+)
+
+// A CodeType distinguishes among go/types.Type encodings.
+type CodeType int
+
+func (c CodeType) Marker() SyncMarker { return SyncType }
+func (c CodeType) Value() int         { return int(c) }
+
+// Note: These values are public and cannot be changed without
+// updating the go/types importers.
+
+const (
+	TypeBasic CodeType = iota
+	TypeNamed
+	TypePointer
+	TypeSlice
+	TypeArray
+	TypeChan
+	TypeMap
+	TypeSignature
+	TypeStruct
+	TypeInterface
+	TypeUnion
+	TypeTypeParam
+)
+
+// A CodeObj distinguishes among go/types.Object encodings.
+type CodeObj int
+
+func (c CodeObj) Marker() SyncMarker { return SyncCodeObj }
+func (c CodeObj) Value() int         { return int(c) }
+
+// Note: These values are public and cannot be changed without
+// updating the go/types importers.
+
+const (
+	ObjAlias CodeObj = iota
+	ObjConst
+	ObjType
+	ObjFunc
+	ObjVar
+	ObjStub
+)

vendor/golang.org/x/tools/internal/pkgbits/decoder.go

@@ -0,0 +1,434 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pkgbits
+
+import (
+	"encoding/binary"
+	"fmt"
+	"go/constant"
+	"go/token"
+	"io"
+	"math/big"
+	"os"
+	"runtime"
+	"strings"
+)
+
+// A PkgDecoder provides methods for decoding a package's Unified IR
+// export data.
+type PkgDecoder struct {
+	// version is the file format version.
+	version uint32
+
+	// sync indicates whether the file uses sync markers.
+	sync bool
+
+	// pkgPath is the package path for the package to be decoded.
+	//
+	// TODO(mdempsky): Remove; unneeded since CL 391014.
+	pkgPath string
+
+	// elemData is the full data payload of the encoded package.
+	// Elements are densely and contiguously packed together.
+	//
+	// The last 8 bytes of elemData are the package fingerprint.
+	elemData string
+
+	// elemEnds stores the byte-offset end positions of element
+	// bitstreams within elemData.
+	//
+	// For example, element I's bitstream data starts at elemEnds[I-1]
+	// (or 0, if I==0) and ends at elemEnds[I].
+	//
+	// Note: elemEnds is indexed by absolute indices, not
+	// section-relative indices.
+	elemEnds []uint32
+
+	// elemEndsEnds stores the index-offset end positions of relocation
+	// sections within elemEnds.
+	//
+	// For example, section K's end positions start at elemEndsEnds[K-1]
+	// (or 0, if K==0) and end at elemEndsEnds[K].
+	elemEndsEnds [numRelocs]uint32
+}
+
+// PkgPath returns the package path for the package
+//
+// TODO(mdempsky): Remove; unneeded since CL 391014.
+func (pr *PkgDecoder) PkgPath() string { return pr.pkgPath }
+
+// SyncMarkers reports whether pr uses sync markers.
+func (pr *PkgDecoder) SyncMarkers() bool { return pr.sync }
+
+// NewPkgDecoder returns a PkgDecoder initialized to read the Unified
+// IR export data from input. pkgPath is the package path for the
+// compilation unit that produced the export data.
+//
+// TODO(mdempsky): Remove pkgPath parameter; unneeded since CL 391014.
+func NewPkgDecoder(pkgPath, input string) PkgDecoder {
+	pr := PkgDecoder{
+		pkgPath: pkgPath,
+	}
+
+	// TODO(mdempsky): Implement direct indexing of input string to
+	// avoid copying the position information.
+
+	r := strings.NewReader(input)
+
+	assert(binary.Read(r, binary.LittleEndian, &pr.version) == nil)
+
+	switch pr.version {
+	default:
+		panic(fmt.Errorf("unsupported version: %v", pr.version))
+	case 0:
+		// no flags
+	case 1:
+		var flags uint32
+		assert(binary.Read(r, binary.LittleEndian, &flags) == nil)
+		pr.sync = flags&flagSyncMarkers != 0
+	}
+
+	assert(binary.Read(r, binary.LittleEndian, pr.elemEndsEnds[:]) == nil)
+
+	pr.elemEnds = make([]uint32, pr.elemEndsEnds[len(pr.elemEndsEnds)-1])
+	assert(binary.Read(r, binary.LittleEndian, pr.elemEnds[:]) == nil)
+
+	pos, err := r.Seek(0, io.SeekCurrent)
+	assert(err == nil)
+
+	pr.elemData = input[pos:]
+	assert(len(pr.elemData)-8 == int(pr.elemEnds[len(pr.elemEnds)-1]))
+
+	return pr
+}
+
+// NumElems returns the number of elements in section k.
+func (pr *PkgDecoder) NumElems(k RelocKind) int {
+	count := int(pr.elemEndsEnds[k])
+	if k > 0 {
+		count -= int(pr.elemEndsEnds[k-1])
+	}
+	return count
+}
+
+// TotalElems returns the total number of elements across all sections.
+func (pr *PkgDecoder) TotalElems() int {
+	return len(pr.elemEnds)
+}
+
+// Fingerprint returns the package fingerprint.
+func (pr *PkgDecoder) Fingerprint() [8]byte {
+	var fp [8]byte
+	copy(fp[:], pr.elemData[len(pr.elemData)-8:])
+	return fp
+}
+
+// AbsIdx returns the absolute index for the given (section, index)
+// pair.
+func (pr *PkgDecoder) AbsIdx(k RelocKind, idx Index) int {
+	absIdx := int(idx)
+	if k > 0 {
+		absIdx += int(pr.elemEndsEnds[k-1])
+	}
+	if absIdx >= int(pr.elemEndsEnds[k]) {
+		errorf("%v:%v is out of bounds; %v", k, idx, pr.elemEndsEnds)
+	}
+	return absIdx
+}
+
+// DataIdx returns the raw element bitstream for the given (section,
+// index) pair.
+func (pr *PkgDecoder) DataIdx(k RelocKind, idx Index) string {
+	absIdx := pr.AbsIdx(k, idx)
+
+	var start uint32
+	if absIdx > 0 {
+		start = pr.elemEnds[absIdx-1]
+	}
+	end := pr.elemEnds[absIdx]
+
+	return pr.elemData[start:end]
+}
+
+// StringIdx returns the string value for the given string index.
+func (pr *PkgDecoder) StringIdx(idx Index) string {
+	return pr.DataIdx(RelocString, idx)
+}
+
+// NewDecoder returns a Decoder for the given (section, index) pair,
+// and decodes the given SyncMarker from the element bitstream.
+func (pr *PkgDecoder) NewDecoder(k RelocKind, idx Index, marker SyncMarker) Decoder {
+	r := pr.NewDecoderRaw(k, idx)
+	r.Sync(marker)
+	return r
+}
+
+// NewDecoderRaw returns a Decoder for the given (section, index) pair.
+//
+// Most callers should use NewDecoder instead.
+func (pr *PkgDecoder) NewDecoderRaw(k RelocKind, idx Index) Decoder {
+	r := Decoder{
+		common: pr,
+		k:      k,
+		Idx:    idx,
+	}
+
+	// TODO(mdempsky) r.data.Reset(...) after #44505 is resolved.
+	r.Data = *strings.NewReader(pr.DataIdx(k, idx))
+
+	r.Sync(SyncRelocs)
+	r.Relocs = make([]RelocEnt, r.Len())
+	for i := range r.Relocs {
+		r.Sync(SyncReloc)
+		r.Relocs[i] = RelocEnt{RelocKind(r.Len()), Index(r.Len())}
+	}
+
+	return r
+}
+
+// A Decoder provides methods for decoding an individual element's
+// bitstream data.
+type Decoder struct {
+	common *PkgDecoder
+
+	Relocs []RelocEnt
+	Data   strings.Reader
+
+	k   RelocKind
+	Idx Index
+}
+
+func (r *Decoder) checkErr(err error) {
+	if err != nil {
+		errorf("unexpected decoding error: %w", err)
+	}
+}
+
+func (r *Decoder) rawUvarint() uint64 {
+	x, err := binary.ReadUvarint(&r.Data)
+	r.checkErr(err)
+	return x
+}
+
+func (r *Decoder) rawVarint() int64 {
+	ux := r.rawUvarint()
+
+	// Zig-zag decode.
+	x := int64(ux >> 1)
+	if ux&1 != 0 {
+		x = ^x
+	}
+	return x
+}
+
+func (r *Decoder) rawReloc(k RelocKind, idx int) Index {
+	e := r.Relocs[idx]
+	assert(e.Kind == k)
+	return e.Idx
+}
+
+// Sync decodes a sync marker from the element bitstream and asserts
+// that it matches the expected marker.
+//
+// If r.common.sync is false, then Sync is a no-op.
+func (r *Decoder) Sync(mWant SyncMarker) {
+	if !r.common.sync {
+		return
+	}
+
+	pos, _ := r.Data.Seek(0, io.SeekCurrent)
+	mHave := SyncMarker(r.rawUvarint())
+	writerPCs := make([]int, r.rawUvarint())
+	for i := range writerPCs {
+		writerPCs[i] = int(r.rawUvarint())
+	}
+
+	if mHave == mWant {
+		return
+	}
+
+	// There's some tension here between printing:
+	//
+	// (1) full file paths that tools can recognize (e.g., so emacs
+	//     hyperlinks the "file:line" text for easy navigation), or
+	//
+	// (2) short file paths that are easier for humans to read (e.g., by
+	//     omitting redundant or irrelevant details, so it's easier to
+	//     focus on the useful bits that remain).
+	//
+	// The current formatting favors the former, as it seems more
+	// helpful in practice. But perhaps the formatting could be improved
+	// to better address both concerns. For example, use relative file
+	// paths if they would be shorter, or rewrite file paths to contain
+	// "$GOROOT" (like objabi.AbsFile does) if tools can be taught how
+	// to reliably expand that again.
+
+	fmt.Printf("export data desync: package %q, section %v, index %v, offset %v\n", r.common.pkgPath, r.k, r.Idx, pos)
+
+	fmt.Printf("\nfound %v, written at:\n", mHave)
+	if len(writerPCs) == 0 {
+		fmt.Printf("\t[stack trace unavailable; recompile package %q with -d=syncframes]\n", r.common.pkgPath)
+	}
+	for _, pc := range writerPCs {
+		fmt.Printf("\t%s\n", r.common.StringIdx(r.rawReloc(RelocString, pc)))
+	}
+
+	fmt.Printf("\nexpected %v, reading at:\n", mWant)
+	var readerPCs [32]uintptr // TODO(mdempsky): Dynamically size?
+	n := runtime.Callers(2, readerPCs[:])
+	for _, pc := range fmtFrames(readerPCs[:n]...) {
+		fmt.Printf("\t%s\n", pc)
+	}
+
+	// We already printed a stack trace for the reader, so now we can
+	// simply exit. Printing a second one with panic or base.Fatalf
+	// would just be noise.
+	os.Exit(1)
+}
+
+// Bool decodes and returns a bool value from the element bitstream.
+func (r *Decoder) Bool() bool {
+	r.Sync(SyncBool)
+	x, err := r.Data.ReadByte()
+	r.checkErr(err)
+	assert(x < 2)
+	return x != 0
+}
+
+// Int64 decodes and returns an int64 value from the element bitstream.
+func (r *Decoder) Int64() int64 {
+	r.Sync(SyncInt64)
+	return r.rawVarint()
+}
+
+// Int64 decodes and returns a uint64 value from the element bitstream.
+func (r *Decoder) Uint64() uint64 {
+	r.Sync(SyncUint64)
+	return r.rawUvarint()
+}
+
+// Len decodes and returns a non-negative int value from the element bitstream.
+func (r *Decoder) Len() int { x := r.Uint64(); v := int(x); assert(uint64(v) == x); return v }
+
+// Int decodes and returns an int value from the element bitstream.
+func (r *Decoder) Int() int { x := r.Int64(); v := int(x); assert(int64(v) == x); return v }
+
+// Uint decodes and returns a uint value from the element bitstream.
+func (r *Decoder) Uint() uint { x := r.Uint64(); v := uint(x); assert(uint64(v) == x); return v }
+
+// Code decodes a Code value from the element bitstream and returns
+// its ordinal value. It's the caller's responsibility to convert the
+// result to an appropriate Code type.
+//
+// TODO(mdempsky): Ideally this method would have signature "Code[T
+// Code] T" instead, but we don't allow generic methods and the
+// compiler can't depend on generics yet anyway.
+func (r *Decoder) Code(mark SyncMarker) int {
+	r.Sync(mark)
+	return r.Len()
+}
+
+// Reloc decodes a relocation of expected section k from the element
+// bitstream and returns an index to the referenced element.
+func (r *Decoder) Reloc(k RelocKind) Index {
+	r.Sync(SyncUseReloc)
+	return r.rawReloc(k, r.Len())
+}
+
+// String decodes and returns a string value from the element
+// bitstream.
+func (r *Decoder) String() string {
+	r.Sync(SyncString)
+	return r.common.StringIdx(r.Reloc(RelocString))
+}
+
+// Strings decodes and returns a variable-length slice of strings from
+// the element bitstream.
+func (r *Decoder) Strings() []string {
+	res := make([]string, r.Len())
+	for i := range res {
+		res[i] = r.String()
+	}
+	return res
+}
+
+// Value decodes and returns a constant.Value from the element
+// bitstream.
+func (r *Decoder) Value() constant.Value {
+	r.Sync(SyncValue)
+	isComplex := r.Bool()
+	val := r.scalar()
+	if isComplex {
+		val = constant.BinaryOp(val, token.ADD, constant.MakeImag(r.scalar()))
+	}
+	return val
+}
+
+func (r *Decoder) scalar() constant.Value {
+	switch tag := CodeVal(r.Code(SyncVal)); tag {
+	default:
+		panic(fmt.Errorf("unexpected scalar tag: %v", tag))
+
+	case ValBool:
+		return constant.MakeBool(r.Bool())
+	case ValString:
+		return constant.MakeString(r.String())
+	case ValInt64:
+		return constant.MakeInt64(r.Int64())
+	case ValBigInt:
+		return constant.Make(r.bigInt())
+	case ValBigRat:
+		num := r.bigInt()
+		denom := r.bigInt()
+		return constant.Make(new(big.Rat).SetFrac(num, denom))
+	case ValBigFloat:
+		return constant.Make(r.bigFloat())
+	}
+}
+
+func (r *Decoder) bigInt() *big.Int {
+	v := new(big.Int).SetBytes([]byte(r.String()))
+	if r.Bool() {
+		v.Neg(v)
+	}
+	return v
+}
+
+func (r *Decoder) bigFloat() *big.Float {
+	v := new(big.Float).SetPrec(512)
+	assert(v.UnmarshalText([]byte(r.String())) == nil)
+	return v
+}
+
+// @@@ Helpers
+
+// TODO(mdempsky): These should probably be removed. I think they're a
+// smell that the export data format is not yet quite right.
+
+// PeekPkgPath returns the package path for the specified package
+// index.
+func (pr *PkgDecoder) PeekPkgPath(idx Index) string {
+	r := pr.NewDecoder(RelocPkg, idx, SyncPkgDef)
+	path := r.String()
+	if path == "" {
+		path = pr.pkgPath
+	}
+	return path
+}
+
+// PeekObj returns the package path, object name, and CodeObj for the
+// specified object index.
+func (pr *PkgDecoder) PeekObj(idx Index) (string, string, CodeObj) {
+	r := pr.NewDecoder(RelocName, idx, SyncObject1)
+	r.Sync(SyncSym)
+	r.Sync(SyncPkg)
+	path := pr.PeekPkgPath(r.Reloc(RelocPkg))
+	name := r.String()
+	assert(name != "")
+
+	tag := CodeObj(r.Code(SyncCodeObj))
+
+	return path, name, tag
+}

vendor/golang.org/x/tools/internal/pkgbits/doc.go

@@ -0,0 +1,32 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package pkgbits implements low-level coding abstractions for
+// Unified IR's export data format.
+//
+// At a low-level, a package is a collection of bitstream elements.
+// Each element has a "kind" and a dense, non-negative index.
+// Elements can be randomly accessed given their kind and index.
+//
+// Individual elements are sequences of variable-length values (e.g.,
+// integers, booleans, strings, go/constant values, cross-references
+// to other elements). Package pkgbits provides APIs for encoding and
+// decoding these low-level values, but the details of mapping
+// higher-level Go constructs into elements is left to higher-level
+// abstractions.
+//
+// Elements may cross-reference each other with "relocations." For
+// example, an element representing a pointer type has a relocation
+// referring to the element type.
+//
+// Go constructs may be composed as a constellation of multiple
+// elements. For example, a declared function may have one element to
+// describe the object (e.g., its name, type, position), and a
+// separate element to describe its function body. This allows readers
+// some flexibility in efficiently seeking or re-reading data (e.g.,
+// inlining requires re-reading the function body for each inlined
+// call, without needing to re-read the object-level details).
+//
+// This is a copy of internal/pkgbits in the Go implementation.
+package pkgbits

vendor/golang.org/x/tools/internal/pkgbits/encoder.go

@@ -0,0 +1,383 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pkgbits
+
+import (
+	"bytes"
+	"crypto/md5"
+	"encoding/binary"
+	"go/constant"
+	"io"
+	"math/big"
+	"runtime"
+)
+
+// currentVersion is the current version number.
+//
+//   - v0: initial prototype
+//
+//   - v1: adds the flags uint32 word
+const currentVersion uint32 = 1
+
+// A PkgEncoder provides methods for encoding a package's Unified IR
+// export data.
+type PkgEncoder struct {
+	// elems holds the bitstream for previously encoded elements.
+	elems [numRelocs][]string
+
+	// stringsIdx maps previously encoded strings to their index within
+	// the RelocString section, to allow deduplication. That is,
+	// elems[RelocString][stringsIdx[s]] == s (if present).
+	stringsIdx map[string]Index
+
+	// syncFrames is the number of frames to write at each sync
+	// marker. A negative value means sync markers are omitted.
+	syncFrames int
+}
+
+// SyncMarkers reports whether pw uses sync markers.
+func (pw *PkgEncoder) SyncMarkers() bool { return pw.syncFrames >= 0 }
+
+// NewPkgEncoder returns an initialized PkgEncoder.
+//
+// syncFrames is the number of caller frames that should be serialized
+// at Sync points. Serializing additional frames results in larger
+// export data files, but can help diagnosing desync errors in
+// higher-level Unified IR reader/writer code. If syncFrames is
+// negative, then sync markers are omitted entirely.
+func NewPkgEncoder(syncFrames int) PkgEncoder {
+	return PkgEncoder{
+		stringsIdx: make(map[string]Index),
+		syncFrames: syncFrames,
+	}
+}
+
+// DumpTo writes the package's encoded data to out0 and returns the
+// package fingerprint.
+func (pw *PkgEncoder) DumpTo(out0 io.Writer) (fingerprint [8]byte) {
+	h := md5.New()
+	out := io.MultiWriter(out0, h)
+
+	writeUint32 := func(x uint32) {
+		assert(binary.Write(out, binary.LittleEndian, x) == nil)
+	}
+
+	writeUint32(currentVersion)
+
+	var flags uint32
+	if pw.SyncMarkers() {
+		flags |= flagSyncMarkers
+	}
+	writeUint32(flags)
+
+	// Write elemEndsEnds.
+	var sum uint32
+	for _, elems := range &pw.elems {
+		sum += uint32(len(elems))
+		writeUint32(sum)
+	}
+
+	// Write elemEnds.
+	sum = 0
+	for _, elems := range &pw.elems {
+		for _, elem := range elems {
+			sum += uint32(len(elem))
+			writeUint32(sum)
+		}
+	}
+
+	// Write elemData.
+	for _, elems := range &pw.elems {
+		for _, elem := range elems {
+			_, err := io.WriteString(out, elem)
+			assert(err == nil)
+		}
+	}
+
+	// Write fingerprint.
+	copy(fingerprint[:], h.Sum(nil))
+	_, err := out0.Write(fingerprint[:])
+	assert(err == nil)
+
+	return
+}
+
+// StringIdx adds a string value to the strings section, if not
+// already present, and returns its index.
+func (pw *PkgEncoder) StringIdx(s string) Index {
+	if idx, ok := pw.stringsIdx[s]; ok {
+		assert(pw.elems[RelocString][idx] == s)
+		return idx
+	}
+
+	idx := Index(len(pw.elems[RelocString]))
+	pw.elems[RelocString] = append(pw.elems[RelocString], s)
+	pw.stringsIdx[s] = idx
+	return idx
+}
+
+// NewEncoder returns an Encoder for a new element within the given
+// section, and encodes the given SyncMarker as the start of the
+// element bitstream.
+func (pw *PkgEncoder) NewEncoder(k RelocKind, marker SyncMarker) Encoder {
+	e := pw.NewEncoderRaw(k)
+	e.Sync(marker)
+	return e
+}
+
+// NewEncoderRaw returns an Encoder for a new element within the given
+// section.
+//
+// Most callers should use NewEncoder instead.
+func (pw *PkgEncoder) NewEncoderRaw(k RelocKind) Encoder {
+	idx := Index(len(pw.elems[k]))
+	pw.elems[k] = append(pw.elems[k], "") // placeholder
+
+	return Encoder{
+		p:   pw,
+		k:   k,
+		Idx: idx,
+	}
+}
+
+// An Encoder provides methods for encoding an individual element's
+// bitstream data.
+type Encoder struct {
+	p *PkgEncoder
+
+	Relocs   []RelocEnt
+	RelocMap map[RelocEnt]uint32
+	Data     bytes.Buffer // accumulated element bitstream data
+
+	encodingRelocHeader bool
+
+	k   RelocKind
+	Idx Index // index within relocation section
+}
+
+// Flush finalizes the element's bitstream and returns its Index.
+func (w *Encoder) Flush() Index {
+	var sb bytes.Buffer // TODO(mdempsky): strings.Builder after #44505 is resolved
+
+	// Backup the data so we write the relocations at the front.
+	var tmp bytes.Buffer
+	io.Copy(&tmp, &w.Data)
+
+	// TODO(mdempsky): Consider writing these out separately so they're
+	// easier to strip, along with function bodies, so that we can prune
+	// down to just the data that's relevant to go/types.
+	if w.encodingRelocHeader {
+		panic("encodingRelocHeader already true; recursive flush?")
+	}
+	w.encodingRelocHeader = true
+	w.Sync(SyncRelocs)
+	w.Len(len(w.Relocs))
+	for _, rEnt := range w.Relocs {
+		w.Sync(SyncReloc)
+		w.Len(int(rEnt.Kind))
+		w.Len(int(rEnt.Idx))
+	}
+
+	io.Copy(&sb, &w.Data)
+	io.Copy(&sb, &tmp)
+	w.p.elems[w.k][w.Idx] = sb.String()
+
+	return w.Idx
+}
+
+func (w *Encoder) checkErr(err error) {
+	if err != nil {
+		errorf("unexpected encoding error: %v", err)
+	}
+}
+
+func (w *Encoder) rawUvarint(x uint64) {
+	var buf [binary.MaxVarintLen64]byte
+	n := binary.PutUvarint(buf[:], x)
+	_, err := w.Data.Write(buf[:n])
+	w.checkErr(err)
+}
+
+func (w *Encoder) rawVarint(x int64) {
+	// Zig-zag encode.
+	ux := uint64(x) << 1
+	if x < 0 {
+		ux = ^ux
+	}
+
+	w.rawUvarint(ux)
+}
+
+func (w *Encoder) rawReloc(r RelocKind, idx Index) int {
+	e := RelocEnt{r, idx}
+	if w.RelocMap != nil {
+		if i, ok := w.RelocMap[e]; ok {
+			return int(i)
+		}
+	} else {
+		w.RelocMap = make(map[RelocEnt]uint32)
+	}
+
+	i := len(w.Relocs)
+	w.RelocMap[e] = uint32(i)
+	w.Relocs = append(w.Relocs, e)
+	return i
+}
+
+func (w *Encoder) Sync(m SyncMarker) {
+	if !w.p.SyncMarkers() {
+		return
+	}
+
+	// Writing out stack frame string references requires working
+	// relocations, but writing out the relocations themselves involves
+	// sync markers. To prevent infinite recursion, we simply trim the
+	// stack frame for sync markers within the relocation header.
+	var frames []string
+	if !w.encodingRelocHeader && w.p.syncFrames > 0 {
+		pcs := make([]uintptr, w.p.syncFrames)
+		n := runtime.Callers(2, pcs)
+		frames = fmtFrames(pcs[:n]...)
+	}
+
+	// TODO(mdempsky): Save space by writing out stack frames as a
+	// linked list so we can share common stack frames.
+	w.rawUvarint(uint64(m))
+	w.rawUvarint(uint64(len(frames)))
+	for _, frame := range frames {
+		w.rawUvarint(uint64(w.rawReloc(RelocString, w.p.StringIdx(frame))))
+	}
+}
+
+// Bool encodes and writes a bool value into the element bitstream,
+// and then returns the bool value.
+//
+// For simple, 2-alternative encodings, the idiomatic way to call Bool
+// is something like:
+//
+//	if w.Bool(x != 0) {
+//		// alternative #1
+//	} else {
+//		// alternative #2
+//	}
+//
+// For multi-alternative encodings, use Code instead.
+func (w *Encoder) Bool(b bool) bool {
+	w.Sync(SyncBool)
+	var x byte
+	if b {
+		x = 1
+	}
+	err := w.Data.WriteByte(x)
+	w.checkErr(err)
+	return b
+}
+
+// Int64 encodes and writes an int64 value into the element bitstream.
+func (w *Encoder) Int64(x int64) {
+	w.Sync(SyncInt64)
+	w.rawVarint(x)
+}
+
+// Uint64 encodes and writes a uint64 value into the element bitstream.
+func (w *Encoder) Uint64(x uint64) {
+	w.Sync(SyncUint64)
+	w.rawUvarint(x)
+}
+
+// Len encodes and writes a non-negative int value into the element bitstream.
+func (w *Encoder) Len(x int) { assert(x >= 0); w.Uint64(uint64(x)) }
+
+// Int encodes and writes an int value into the element bitstream.
+func (w *Encoder) Int(x int) { w.Int64(int64(x)) }
+
+// Len encodes and writes a uint value into the element bitstream.
+func (w *Encoder) Uint(x uint) { w.Uint64(uint64(x)) }
+
+// Reloc encodes and writes a relocation for the given (section,
+// index) pair into the element bitstream.
+//
+// Note: Only the index is formally written into the element
+// bitstream, so bitstream decoders must know from context which
+// section an encoded relocation refers to.
+func (w *Encoder) Reloc(r RelocKind, idx Index) {
+	w.Sync(SyncUseReloc)
+	w.Len(w.rawReloc(r, idx))
+}
+
+// Code encodes and writes a Code value into the element bitstream.
+func (w *Encoder) Code(c Code) {
+	w.Sync(c.Marker())
+	w.Len(c.Value())
+}
+
+// String encodes and writes a string value into the element
+// bitstream.
+//
+// Internally, strings are deduplicated by adding them to the strings
+// section (if not already present), and then writing a relocation
+// into the element bitstream.
+func (w *Encoder) String(s string) {
+	w.Sync(SyncString)
+	w.Reloc(RelocString, w.p.StringIdx(s))
+}
+
+// Strings encodes and writes a variable-length slice of strings into
+// the element bitstream.
+func (w *Encoder) Strings(ss []string) {
+	w.Len(len(ss))
+	for _, s := range ss {
+		w.String(s)
+	}
+}
+
+// Value encodes and writes a constant.Value into the element
+// bitstream.
+func (w *Encoder) Value(val constant.Value) {
+	w.Sync(SyncValue)
+	if w.Bool(val.Kind() == constant.Complex) {
+		w.scalar(constant.Real(val))
+		w.scalar(constant.Imag(val))
+	} else {
+		w.scalar(val)
+	}
+}
+
+func (w *Encoder) scalar(val constant.Value) {
+	switch v := constant.Val(val).(type) {
+	default:
+		errorf("unhandled %v (%v)", val, val.Kind())
+	case bool:
+		w.Code(ValBool)
+		w.Bool(v)
+	case string:
+		w.Code(ValString)
+		w.String(v)
+	case int64:
+		w.Code(ValInt64)
+		w.Int64(v)
+	case *big.Int:
+		w.Code(ValBigInt)
+		w.bigInt(v)
+	case *big.Rat:
+		w.Code(ValBigRat)
+		w.bigInt(v.Num())
+		w.bigInt(v.Denom())
+	case *big.Float:
+		w.Code(ValBigFloat)
+		w.bigFloat(v)
+	}
+}
+
+func (w *Encoder) bigInt(v *big.Int) {
+	b := v.Bytes()
+	w.String(string(b)) // TODO: More efficient encoding.
+	w.Bool(v.Sign() < 0)
+}
+
+func (w *Encoder) bigFloat(v *big.Float) {
+	b := v.Append(nil, 'p', -1)
+	w.String(string(b)) // TODO: More efficient encoding.
+}

vendor/golang.org/x/tools/internal/pkgbits/flags.go

@@ -0,0 +1,9 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pkgbits
+
+const (
+	flagSyncMarkers = 1 << iota // file format contains sync markers
+)

vendor/golang.org/x/tools/internal/pkgbits/frames_go1.go

@@ -0,0 +1,21 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.7
+// +build !go1.7
+
+// TODO(mdempsky): Remove after #44505 is resolved
+
+package pkgbits
+
+import "runtime"
+
+func walkFrames(pcs []uintptr, visit frameVisitor) {
+	for _, pc := range pcs {
+		fn := runtime.FuncForPC(pc)
+		file, line := fn.FileLine(pc)
+
+		visit(file, line, fn.Name(), pc-fn.Entry())
+	}
+}

vendor/golang.org/x/tools/internal/pkgbits/frames_go17.go

@@ -0,0 +1,28 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.7
+// +build go1.7
+
+package pkgbits
+
+import "runtime"
+
+// walkFrames calls visit for each call frame represented by pcs.
+//
+// pcs should be a slice of PCs, as returned by runtime.Callers.
+func walkFrames(pcs []uintptr, visit frameVisitor) {
+	if len(pcs) == 0 {
+		return
+	}
+
+	frames := runtime.CallersFrames(pcs)
+	for {
+		frame, more := frames.Next()
+		visit(frame.File, frame.Line, frame.Function, frame.PC-frame.Entry)
+		if !more {
+			return
+		}
+	}
+}

vendor/golang.org/x/tools/internal/pkgbits/reloc.go

@@ -0,0 +1,42 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pkgbits
+
+// A RelocKind indicates a particular section within a unified IR export.
+type RelocKind int32
+
+// An Index represents a bitstream element index within a particular
+// section.
+type Index int32
+
+// A relocEnt (relocation entry) is an entry in an element's local
+// reference table.
+//
+// TODO(mdempsky): Rename this too.
+type RelocEnt struct {
+	Kind RelocKind
+	Idx  Index
+}
+
+// Reserved indices within the meta relocation section.
+const (
+	PublicRootIdx  Index = 0
+	PrivateRootIdx Index = 1
+)
+
+const (
+	RelocString RelocKind = iota
+	RelocMeta
+	RelocPosBase
+	RelocPkg
+	RelocName
+	RelocType
+	RelocObj
+	RelocObjExt
+	RelocObjDict
+	RelocBody
+
+	numRelocs = iota
+)

vendor/golang.org/x/tools/internal/pkgbits/support.go

@@ -0,0 +1,17 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pkgbits
+
+import "fmt"
+
+func assert(b bool) {
+	if !b {
+		panic("assertion failed")
+	}
+}
+
+func errorf(format string, args ...interface{}) {
+	panic(fmt.Errorf(format, args...))
+}

vendor/golang.org/x/tools/internal/pkgbits/sync.go

@@ -0,0 +1,113 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pkgbits
+
+import (
+	"fmt"
+	"strings"
+)
+
+// fmtFrames formats a backtrace for reporting reader/writer desyncs.
+func fmtFrames(pcs ...uintptr) []string {
+	res := make([]string, 0, len(pcs))
+	walkFrames(pcs, func(file string, line int, name string, offset uintptr) {
+		// Trim package from function name. It's just redundant noise.
+		name = strings.TrimPrefix(name, "cmd/compile/internal/noder.")
+
+		res = append(res, fmt.Sprintf("%s:%v: %s +0x%v", file, line, name, offset))
+	})
+	return res
+}
+
+type frameVisitor func(file string, line int, name string, offset uintptr)
+
+// SyncMarker is an enum type that represents markers that may be
+// written to export data to ensure the reader and writer stay
+// synchronized.
+type SyncMarker int
+
+//go:generate stringer -type=SyncMarker -trimprefix=Sync
+
+const (
+	_ SyncMarker = iota
+
+	// Public markers (known to go/types importers).
+
+	// Low-level coding markers.
+	SyncEOF
+	SyncBool
+	SyncInt64
+	SyncUint64
+	SyncString
+	SyncValue
+	SyncVal
+	SyncRelocs
+	SyncReloc
+	SyncUseReloc
+
+	// Higher-level object and type markers.
+	SyncPublic
+	SyncPos
+	SyncPosBase
+	SyncObject
+	SyncObject1
+	SyncPkg
+	SyncPkgDef
+	SyncMethod
+	SyncType
+	SyncTypeIdx
+	SyncTypeParamNames
+	SyncSignature
+	SyncParams
+	SyncParam
+	SyncCodeObj
+	SyncSym
+	SyncLocalIdent
+	SyncSelector
+
+	// Private markers (only known to cmd/compile).
+	SyncPrivate
+
+	SyncFuncExt
+	SyncVarExt
+	SyncTypeExt
+	SyncPragma
+
+	SyncExprList
+	SyncExprs
+	SyncExpr
+	SyncExprType
+	SyncAssign
+	SyncOp
+	SyncFuncLit
+	SyncCompLit
+
+	SyncDecl
+	SyncFuncBody
+	SyncOpenScope
+	SyncCloseScope
+	SyncCloseAnotherScope
+	SyncDeclNames
+	SyncDeclName
+
+	SyncStmts
+	SyncBlockStmt
+	SyncIfStmt
+	SyncForStmt
+	SyncSwitchStmt
+	SyncRangeStmt
+	SyncCaseClause
+	SyncCommClause
+	SyncSelectStmt
+	SyncDecls
+	SyncLabeledStmt
+	SyncUseObjLocal
+	SyncAddLocal
+	SyncLinkname
+	SyncStmt1
+	SyncStmtsEnd
+	SyncLabel
+	SyncOptLabel
+)

vendor/golang.org/x/tools/internal/pkgbits/syncmarker_string.go

@@ -0,0 +1,89 @@
+// Code generated by "stringer -type=SyncMarker -trimprefix=Sync"; DO NOT EDIT.
+
+package pkgbits
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[SyncEOF-1]
+	_ = x[SyncBool-2]
+	_ = x[SyncInt64-3]
+	_ = x[SyncUint64-4]
+	_ = x[SyncString-5]
+	_ = x[SyncValue-6]
+	_ = x[SyncVal-7]
+	_ = x[SyncRelocs-8]
+	_ = x[SyncReloc-9]
+	_ = x[SyncUseReloc-10]
+	_ = x[SyncPublic-11]
+	_ = x[SyncPos-12]
+	_ = x[SyncPosBase-13]
+	_ = x[SyncObject-14]
+	_ = x[SyncObject1-15]
+	_ = x[SyncPkg-16]
+	_ = x[SyncPkgDef-17]
+	_ = x[SyncMethod-18]
+	_ = x[SyncType-19]
+	_ = x[SyncTypeIdx-20]
+	_ = x[SyncTypeParamNames-21]
+	_ = x[SyncSignature-22]
+	_ = x[SyncParams-23]
+	_ = x[SyncParam-24]
+	_ = x[SyncCodeObj-25]
+	_ = x[SyncSym-26]
+	_ = x[SyncLocalIdent-27]
+	_ = x[SyncSelector-28]
+	_ = x[SyncPrivate-29]
+	_ = x[SyncFuncExt-30]
+	_ = x[SyncVarExt-31]
+	_ = x[SyncTypeExt-32]
+	_ = x[SyncPragma-33]
+	_ = x[SyncExprList-34]
+	_ = x[SyncExprs-35]
+	_ = x[SyncExpr-36]
+	_ = x[SyncExprType-37]
+	_ = x[SyncAssign-38]
+	_ = x[SyncOp-39]
+	_ = x[SyncFuncLit-40]
+	_ = x[SyncCompLit-41]
+	_ = x[SyncDecl-42]
+	_ = x[SyncFuncBody-43]
+	_ = x[SyncOpenScope-44]
+	_ = x[SyncCloseScope-45]
+	_ = x[SyncCloseAnotherScope-46]
+	_ = x[SyncDeclNames-47]
+	_ = x[SyncDeclName-48]
+	_ = x[SyncStmts-49]
+	_ = x[SyncBlockStmt-50]
+	_ = x[SyncIfStmt-51]
+	_ = x[SyncForStmt-52]
+	_ = x[SyncSwitchStmt-53]
+	_ = x[SyncRangeStmt-54]
+	_ = x[SyncCaseClause-55]
+	_ = x[SyncCommClause-56]
+	_ = x[SyncSelectStmt-57]
+	_ = x[SyncDecls-58]
+	_ = x[SyncLabeledStmt-59]
+	_ = x[SyncUseObjLocal-60]
+	_ = x[SyncAddLocal-61]
+	_ = x[SyncLinkname-62]
+	_ = x[SyncStmt1-63]
+	_ = x[SyncStmtsEnd-64]
+	_ = x[SyncLabel-65]
+	_ = x[SyncOptLabel-66]
+}
+
+const _SyncMarker_name = "EOFBoolInt64Uint64StringValueValRelocsRelocUseRelocPublicPosPosBaseObjectObject1PkgPkgDefMethodTypeTypeIdxTypeParamNamesSignatureParamsParamCodeObjSymLocalIdentSelectorPrivateFuncExtVarExtTypeExtPragmaExprListExprsExprExprTypeAssignOpFuncLitCompLitDeclFuncBodyOpenScopeCloseScopeCloseAnotherScopeDeclNamesDeclNameStmtsBlockStmtIfStmtForStmtSwitchStmtRangeStmtCaseClauseCommClauseSelectStmtDeclsLabeledStmtUseObjLocalAddLocalLinknameStmt1StmtsEndLabelOptLabel"
+
+var _SyncMarker_index = [...]uint16{0, 3, 7, 12, 18, 24, 29, 32, 38, 43, 51, 57, 60, 67, 73, 80, 83, 89, 95, 99, 106, 120, 129, 135, 140, 147, 150, 160, 168, 175, 182, 188, 195, 201, 209, 214, 218, 226, 232, 234, 241, 248, 252, 260, 269, 279, 296, 305, 313, 318, 327, 333, 340, 350, 359, 369, 379, 389, 394, 405, 416, 424, 432, 437, 445, 450, 458}
+
+func (i SyncMarker) String() string {
+	i -= 1
+	if i < 0 || i >= SyncMarker(len(_SyncMarker_index)-1) {
+		return "SyncMarker(" + strconv.FormatInt(int64(i+1), 10) + ")"
+	}
+	return _SyncMarker_name[_SyncMarker_index[i]:_SyncMarker_index[i+1]]
+}

vendor/golang.org/x/tools/internal/typeparams/common.go

@@ -0,0 +1,179 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package typeparams contains common utilities for writing tools that interact
+// with generic Go code, as introduced with Go 1.18.
+//
+// Many of the types and functions in this package are proxies for the new APIs
+// introduced in the standard library with Go 1.18. For example, the
+// typeparams.Union type is an alias for go/types.Union, and the ForTypeSpec
+// function returns the value of the go/ast.TypeSpec.TypeParams field. At Go
+// versions older than 1.18 these helpers are implemented as stubs, allowing
+// users of this package to write code that handles generic constructs inline,
+// even if the Go version being used to compile does not support generics.
+//
+// Additionally, this package contains common utilities for working with the
+// new generic constructs, to supplement the standard library APIs. Notably,
+// the StructuralTerms API computes a minimal representation of the structural
+// restrictions on a type parameter.
+//
+// An external version of these APIs is available in the
+// golang.org/x/exp/typeparams module.
+package typeparams
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+)
+
+// UnpackIndexExpr extracts data from AST nodes that represent index
+// expressions.
+//
+// For an ast.IndexExpr, the resulting indices slice will contain exactly one
+// index expression. For an ast.IndexListExpr (go1.18+), it may have a variable
+// number of index expressions.
+//
+// For nodes that don't represent index expressions, the first return value of
+// UnpackIndexExpr will be nil.
+func UnpackIndexExpr(n ast.Node) (x ast.Expr, lbrack token.Pos, indices []ast.Expr, rbrack token.Pos) {
+	switch e := n.(type) {
+	case *ast.IndexExpr:
+		return e.X, e.Lbrack, []ast.Expr{e.Index}, e.Rbrack
+	case *IndexListExpr:
+		return e.X, e.Lbrack, e.Indices, e.Rbrack
+	}
+	return nil, token.NoPos, nil, token.NoPos
+}
+
+// PackIndexExpr returns an *ast.IndexExpr or *ast.IndexListExpr, depending on
+// the cardinality of indices. Calling PackIndexExpr with len(indices) == 0
+// will panic.
+func PackIndexExpr(x ast.Expr, lbrack token.Pos, indices []ast.Expr, rbrack token.Pos) ast.Expr {
+	switch len(indices) {
+	case 0:
+		panic("empty indices")
+	case 1:
+		return &ast.IndexExpr{
+			X:      x,
+			Lbrack: lbrack,
+			Index:  indices[0],
+			Rbrack: rbrack,
+		}
+	default:
+		return &IndexListExpr{
+			X:       x,
+			Lbrack:  lbrack,
+			Indices: indices,
+			Rbrack:  rbrack,
+		}
+	}
+}
+
+// IsTypeParam reports whether t is a type parameter.
+func IsTypeParam(t types.Type) bool {
+	_, ok := t.(*TypeParam)
+	return ok
+}
+
+// OriginMethod returns the origin method associated with the method fn.
+// For methods on a non-generic receiver base type, this is just
+// fn. However, for methods with a generic receiver, OriginMethod returns the
+// corresponding method in the method set of the origin type.
+//
+// As a special case, if fn is not a method (has no receiver), OriginMethod
+// returns fn.
+func OriginMethod(fn *types.Func) *types.Func {
+	recv := fn.Type().(*types.Signature).Recv()
+	if recv == nil {
+
+		return fn
+	}
+	base := recv.Type()
+	p, isPtr := base.(*types.Pointer)
+	if isPtr {
+		base = p.Elem()
+	}
+	named, isNamed := base.(*types.Named)
+	if !isNamed {
+		// Receiver is a *types.Interface.
+		return fn
+	}
+	if ForNamed(named).Len() == 0 {
+		// Receiver base has no type parameters, so we can avoid the lookup below.
+		return fn
+	}
+	orig := NamedTypeOrigin(named)
+	gfn, _, _ := types.LookupFieldOrMethod(orig, true, fn.Pkg(), fn.Name())
+	return gfn.(*types.Func)
+}
+
+// GenericAssignableTo is a generalization of types.AssignableTo that
+// implements the following rule for uninstantiated generic types:
+//
+// If V and T are generic named types, then V is considered assignable to T if,
+// for every possible instantation of V[A_1, ..., A_N], the instantiation
+// T[A_1, ..., A_N] is valid and V[A_1, ..., A_N] implements T[A_1, ..., A_N].
+//
+// If T has structural constraints, they must be satisfied by V.
+//
+// For example, consider the following type declarations:
+//
+//	type Interface[T any] interface {
+//		Accept(T)
+//	}
+//
+//	type Container[T any] struct {
+//		Element T
+//	}
+//
+//	func (c Container[T]) Accept(t T) { c.Element = t }
+//
+// In this case, GenericAssignableTo reports that instantiations of Container
+// are assignable to the corresponding instantiation of Interface.
+func GenericAssignableTo(ctxt *Context, V, T types.Type) bool {
+	// If V and T are not both named, or do not have matching non-empty type
+	// parameter lists, fall back on types.AssignableTo.
+
+	VN, Vnamed := V.(*types.Named)
+	TN, Tnamed := T.(*types.Named)
+	if !Vnamed || !Tnamed {
+		return types.AssignableTo(V, T)
+	}
+
+	vtparams := ForNamed(VN)
+	ttparams := ForNamed(TN)
+	if vtparams.Len() == 0 || vtparams.Len() != ttparams.Len() || NamedTypeArgs(VN).Len() != 0 || NamedTypeArgs(TN).Len() != 0 {
+		return types.AssignableTo(V, T)
+	}
+
+	// V and T have the same (non-zero) number of type params. Instantiate both
+	// with the type parameters of V. This must always succeed for V, and will
+	// succeed for T if and only if the type set of each type parameter of V is a
+	// subset of the type set of the corresponding type parameter of T, meaning
+	// that every instantiation of V corresponds to a valid instantiation of T.
+
+	// Minor optimization: ensure we share a context across the two
+	// instantiations below.
+	if ctxt == nil {
+		ctxt = NewContext()
+	}
+
+	var targs []types.Type
+	for i := 0; i < vtparams.Len(); i++ {
+		targs = append(targs, vtparams.At(i))
+	}
+
+	vinst, err := Instantiate(ctxt, V, targs, true)
+	if err != nil {
+		panic("type parameters should satisfy their own constraints")
+	}
+
+	tinst, err := Instantiate(ctxt, T, targs, true)
+	if err != nil {
+		return false
+	}
+
+	return types.AssignableTo(vinst, tinst)
+}

vendor/golang.org/x/tools/internal/typeparams/coretype.go

@@ -0,0 +1,122 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typeparams
+
+import (
+	"go/types"
+)
+
+// CoreType returns the core type of T or nil if T does not have a core type.
+//
+// See https://go.dev/ref/spec#Core_types for the definition of a core type.
+func CoreType(T types.Type) types.Type {
+	U := T.Underlying()
+	if _, ok := U.(*types.Interface); !ok {
+		return U // for non-interface types,
+	}
+
+	terms, err := _NormalTerms(U)
+	if len(terms) == 0 || err != nil {
+		// len(terms) -> empty type set of interface.
+		// err != nil => U is invalid, exceeds complexity bounds, or has an empty type set.
+		return nil // no core type.
+	}
+
+	U = terms[0].Type().Underlying()
+	var identical int // i in [0,identical) => Identical(U, terms[i].Type().Underlying())
+	for identical = 1; identical < len(terms); identical++ {
+		if !types.Identical(U, terms[identical].Type().Underlying()) {
+			break
+		}
+	}
+
+	if identical == len(terms) {
+		// https://go.dev/ref/spec#Core_types
+		// "There is a single type U which is the underlying type of all types in the type set of T"
+		return U
+	}
+	ch, ok := U.(*types.Chan)
+	if !ok {
+		return nil // no core type as identical < len(terms) and U is not a channel.
+	}
+	// https://go.dev/ref/spec#Core_types
+	// "the type chan E if T contains only bidirectional channels, or the type chan<- E or
+	// <-chan E depending on the direction of the directional channels present."
+	for chans := identical; chans < len(terms); chans++ {
+		curr, ok := terms[chans].Type().Underlying().(*types.Chan)
+		if !ok {
+			return nil
+		}
+		if !types.Identical(ch.Elem(), curr.Elem()) {
+			return nil // channel elements are not identical.
+		}
+		if ch.Dir() == types.SendRecv {
+			// ch is bidirectional. We can safely always use curr's direction.
+			ch = curr
+		} else if curr.Dir() != types.SendRecv && ch.Dir() != curr.Dir() {
+			// ch and curr are not bidirectional and not the same direction.
+			return nil
+		}
+	}
+	return ch
+}
+
+// _NormalTerms returns a slice of terms representing the normalized structural
+// type restrictions of a type, if any.
+//
+// For all types other than *types.TypeParam, *types.Interface, and
+// *types.Union, this is just a single term with Tilde() == false and
+// Type() == typ. For *types.TypeParam, *types.Interface, and *types.Union, see
+// below.
+//
+// Structural type restrictions of a type parameter are created via
+// non-interface types embedded in its constraint interface (directly, or via a
+// chain of interface embeddings). For example, in the declaration type
+// T[P interface{~int; m()}] int the structural restriction of the type
+// parameter P is ~int.
+//
+// With interface embedding and unions, the specification of structural type
+// restrictions may be arbitrarily complex. For example, consider the
+// following:
+//
+//  type A interface{ ~string|~[]byte }
+//
+//  type B interface{ int|string }
+//
+//  type C interface { ~string|~int }
+//
+//  type T[P interface{ A|B; C }] int
+//
+// In this example, the structural type restriction of P is ~string|int: A|B
+// expands to ~string|~[]byte|int|string, which reduces to ~string|~[]byte|int,
+// which when intersected with C (~string|~int) yields ~string|int.
+//
+// _NormalTerms computes these expansions and reductions, producing a
+// "normalized" form of the embeddings. A structural restriction is normalized
+// if it is a single union containing no interface terms, and is minimal in the
+// sense that removing any term changes the set of types satisfying the
+// constraint. It is left as a proof for the reader that, modulo sorting, there
+// is exactly one such normalized form.
+//
+// Because the minimal representation always takes this form, _NormalTerms
+// returns a slice of tilde terms corresponding to the terms of the union in
+// the normalized structural restriction. An error is returned if the type is
+// invalid, exceeds complexity bounds, or has an empty type set. In the latter
+// case, _NormalTerms returns ErrEmptyTypeSet.
+//
+// _NormalTerms makes no guarantees about the order of terms, except that it
+// is deterministic.
+func _NormalTerms(typ types.Type) ([]*Term, error) {
+	switch typ := typ.(type) {
+	case *TypeParam:
+		return StructuralTerms(typ)
+	case *Union:
+		return UnionTermSet(typ)
+	case *types.Interface:
+		return InterfaceTermSet(typ)
+	default:
+		return []*Term{NewTerm(false, typ)}, nil
+	}
+}

vendor/golang.org/x/tools/internal/typeparams/enabled_go117.go

@@ -0,0 +1,12 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.18
+// +build !go1.18
+
+package typeparams
+
+// Enabled reports whether type parameters are enabled in the current build
+// environment.
+const Enabled = false

vendor/golang.org/x/tools/internal/typeparams/enabled_go118.go

@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.18
+// +build go1.18
+
+package typeparams
+
+// Note: this constant is in a separate file as this is the only acceptable
+// diff between the <1.18 API of this package and the 1.18 API.
+
+// Enabled reports whether type parameters are enabled in the current build
+// environment.
+const Enabled = true

vendor/golang.org/x/tools/internal/typeparams/normalize.go

@@ -0,0 +1,218 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typeparams
+
+import (
+	"errors"
+	"fmt"
+	"go/types"
+	"os"
+	"strings"
+)
+
+//go:generate go run copytermlist.go
+
+const debug = false
+
+var ErrEmptyTypeSet = errors.New("empty type set")
+
+// StructuralTerms returns a slice of terms representing the normalized
+// structural type restrictions of a type parameter, if any.
+//
+// Structural type restrictions of a type parameter are created via
+// non-interface types embedded in its constraint interface (directly, or via a
+// chain of interface embeddings). For example, in the declaration
+//
+//	type T[P interface{~int; m()}] int
+//
+// the structural restriction of the type parameter P is ~int.
+//
+// With interface embedding and unions, the specification of structural type
+// restrictions may be arbitrarily complex. For example, consider the
+// following:
+//
+//	type A interface{ ~string|~[]byte }
+//
+//	type B interface{ int|string }
+//
+//	type C interface { ~string|~int }
+//
+//	type T[P interface{ A|B; C }] int
+//
+// In this example, the structural type restriction of P is ~string|int: A|B
+// expands to ~string|~[]byte|int|string, which reduces to ~string|~[]byte|int,
+// which when intersected with C (~string|~int) yields ~string|int.
+//
+// StructuralTerms computes these expansions and reductions, producing a
+// "normalized" form of the embeddings. A structural restriction is normalized
+// if it is a single union containing no interface terms, and is minimal in the
+// sense that removing any term changes the set of types satisfying the
+// constraint. It is left as a proof for the reader that, modulo sorting, there
+// is exactly one such normalized form.
+//
+// Because the minimal representation always takes this form, StructuralTerms
+// returns a slice of tilde terms corresponding to the terms of the union in
+// the normalized structural restriction. An error is returned if the
+// constraint interface is invalid, exceeds complexity bounds, or has an empty
+// type set. In the latter case, StructuralTerms returns ErrEmptyTypeSet.
+//
+// StructuralTerms makes no guarantees about the order of terms, except that it
+// is deterministic.
+func StructuralTerms(tparam *TypeParam) ([]*Term, error) {
+	constraint := tparam.Constraint()
+	if constraint == nil {
+		return nil, fmt.Errorf("%s has nil constraint", tparam)
+	}
+	iface, _ := constraint.Underlying().(*types.Interface)
+	if iface == nil {
+		return nil, fmt.Errorf("constraint is %T, not *types.Interface", constraint.Underlying())
+	}
+	return InterfaceTermSet(iface)
+}
+
+// InterfaceTermSet computes the normalized terms for a constraint interface,
+// returning an error if the term set cannot be computed or is empty. In the
+// latter case, the error will be ErrEmptyTypeSet.
+//
+// See the documentation of StructuralTerms for more information on
+// normalization.
+func InterfaceTermSet(iface *types.Interface) ([]*Term, error) {
+	return computeTermSet(iface)
+}
+
+// UnionTermSet computes the normalized terms for a union, returning an error
+// if the term set cannot be computed or is empty. In the latter case, the
+// error will be ErrEmptyTypeSet.
+//
+// See the documentation of StructuralTerms for more information on
+// normalization.
+func UnionTermSet(union *Union) ([]*Term, error) {
+	return computeTermSet(union)
+}
+
+func computeTermSet(typ types.Type) ([]*Term, error) {
+	tset, err := computeTermSetInternal(typ, make(map[types.Type]*termSet), 0)
+	if err != nil {
+		return nil, err
+	}
+	if tset.terms.isEmpty() {
+		return nil, ErrEmptyTypeSet
+	}
+	if tset.terms.isAll() {
+		return nil, nil
+	}
+	var terms []*Term
+	for _, term := range tset.terms {
+		terms = append(terms, NewTerm(term.tilde, term.typ))
+	}
+	return terms, nil
+}
+
+// A termSet holds the normalized set of terms for a given type.
+//
+// The name termSet is intentionally distinct from 'type set': a type set is
+// all types that implement a type (and includes method restrictions), whereas
+// a term set just represents the structural restrictions on a type.
+type termSet struct {
+	complete bool
+	terms    termlist
+}
+
+func indentf(depth int, format string, args ...interface{}) {
+	fmt.Fprintf(os.Stderr, strings.Repeat(".", depth)+format+"\n", args...)
+}
+
+func computeTermSetInternal(t types.Type, seen map[types.Type]*termSet, depth int) (res *termSet, err error) {
+	if t == nil {
+		panic("nil type")
+	}
+
+	if debug {
+		indentf(depth, "%s", t.String())
+		defer func() {
+			if err != nil {
+				indentf(depth, "=> %s", err)
+			} else {
+				indentf(depth, "=> %s", res.terms.String())
+			}
+		}()
+	}
+
+	const maxTermCount = 100
+	if tset, ok := seen[t]; ok {
+		if !tset.complete {
+			return nil, fmt.Errorf("cycle detected in the declaration of %s", t)
+		}
+		return tset, nil
+	}
+
+	// Mark the current type as seen to avoid infinite recursion.
+	tset := new(termSet)
+	defer func() {
+		tset.complete = true
+	}()
+	seen[t] = tset
+
+	switch u := t.Underlying().(type) {
+	case *types.Interface:
+		// The term set of an interface is the intersection of the term sets of its
+		// embedded types.
+		tset.terms = allTermlist
+		for i := 0; i < u.NumEmbeddeds(); i++ {
+			embedded := u.EmbeddedType(i)
+			if _, ok := embedded.Underlying().(*TypeParam); ok {
+				return nil, fmt.Errorf("invalid embedded type %T", embedded)
+			}
+			tset2, err := computeTermSetInternal(embedded, seen, depth+1)
+			if err != nil {
+				return nil, err
+			}
+			tset.terms = tset.terms.intersect(tset2.terms)
+		}
+	case *Union:
+		// The term set of a union is the union of term sets of its terms.
+		tset.terms = nil
+		for i := 0; i < u.Len(); i++ {
+			t := u.Term(i)
+			var terms termlist
+			switch t.Type().Underlying().(type) {
+			case *types.Interface:
+				tset2, err := computeTermSetInternal(t.Type(), seen, depth+1)
+				if err != nil {
+					return nil, err
+				}
+				terms = tset2.terms
+			case *TypeParam, *Union:
+				// A stand-alone type parameter or union is not permitted as union
+				// term.
+				return nil, fmt.Errorf("invalid union term %T", t)
+			default:
+				if t.Type() == types.Typ[types.Invalid] {
+					continue
+				}
+				terms = termlist{{t.Tilde(), t.Type()}}
+			}
+			tset.terms = tset.terms.union(terms)
+			if len(tset.terms) > maxTermCount {
+				return nil, fmt.Errorf("exceeded max term count %d", maxTermCount)
+			}
+		}
+	case *TypeParam:
+		panic("unreachable")
+	default:
+		// For all other types, the term set is just a single non-tilde term
+		// holding the type itself.
+		if u != types.Typ[types.Invalid] {
+			tset.terms = termlist{{false, t}}
+		}
+	}
+	return tset, nil
+}
+
+// under is a facade for the go/types internal function of the same name. It is
+// used by typeterm.go.
+func under(t types.Type) types.Type {
+	return t.Underlying()
+}

vendor/golang.org/x/tools/internal/typeparams/termlist.go

@@ -0,0 +1,163 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by copytermlist.go DO NOT EDIT.
+
+package typeparams
+
+import (
+	"bytes"
+	"go/types"
+)
+
+// A termlist represents the type set represented by the union
+// t1 ∪ y2 ∪ ... tn of the type sets of the terms t1 to tn.
+// A termlist is in normal form if all terms are disjoint.
+// termlist operations don't require the operands to be in
+// normal form.
+type termlist []*term
+
+// allTermlist represents the set of all types.
+// It is in normal form.
+var allTermlist = termlist{new(term)}
+
+// String prints the termlist exactly (without normalization).
+func (xl termlist) String() string {
+	if len(xl) == 0 {
+		return "∅"
+	}
+	var buf bytes.Buffer
+	for i, x := range xl {
+		if i > 0 {
+			buf.WriteString(" ∪ ")
+		}
+		buf.WriteString(x.String())
+	}
+	return buf.String()
+}
+
+// isEmpty reports whether the termlist xl represents the empty set of types.
+func (xl termlist) isEmpty() bool {
+	// If there's a non-nil term, the entire list is not empty.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil {
+			return false
+		}
+	}
+	return true
+}
+
+// isAll reports whether the termlist xl represents the set of all types.
+func (xl termlist) isAll() bool {
+	// If there's a 𝓤 term, the entire list is 𝓤.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil && x.typ == nil {
+			return true
+		}
+	}
+	return false
+}
+
+// norm returns the normal form of xl.
+func (xl termlist) norm() termlist {
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	used := make([]bool, len(xl))
+	var rl termlist
+	for i, xi := range xl {
+		if xi == nil || used[i] {
+			continue
+		}
+		for j := i + 1; j < len(xl); j++ {
+			xj := xl[j]
+			if xj == nil || used[j] {
+				continue
+			}
+			if u1, u2 := xi.union(xj); u2 == nil {
+				// If we encounter a 𝓤 term, the entire list is 𝓤.
+				// Exit early.
+				// (Note that this is not just an optimization;
+				// if we continue, we may end up with a 𝓤 term
+				// and other terms and the result would not be
+				// in normal form.)
+				if u1.typ == nil {
+					return allTermlist
+				}
+				xi = u1
+				used[j] = true // xj is now unioned into xi - ignore it in future iterations
+			}
+		}
+		rl = append(rl, xi)
+	}
+	return rl
+}
+
+// union returns the union xl ∪ yl.
+func (xl termlist) union(yl termlist) termlist {
+	return append(xl, yl...).norm()
+}
+
+// intersect returns the intersection xl ∩ yl.
+func (xl termlist) intersect(yl termlist) termlist {
+	if xl.isEmpty() || yl.isEmpty() {
+		return nil
+	}
+
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	var rl termlist
+	for _, x := range xl {
+		for _, y := range yl {
+			if r := x.intersect(y); r != nil {
+				rl = append(rl, r)
+			}
+		}
+	}
+	return rl.norm()
+}
+
+// equal reports whether xl and yl represent the same type set.
+func (xl termlist) equal(yl termlist) bool {
+	// TODO(gri) this should be more efficient
+	return xl.subsetOf(yl) && yl.subsetOf(xl)
+}
+
+// includes reports whether t ∈ xl.
+func (xl termlist) includes(t types.Type) bool {
+	for _, x := range xl {
+		if x.includes(t) {
+			return true
+		}
+	}
+	return false
+}
+
+// supersetOf reports whether y ⊆ xl.
+func (xl termlist) supersetOf(y *term) bool {
+	for _, x := range xl {
+		if y.subsetOf(x) {
+			return true
+		}
+	}
+	return false
+}
+
+// subsetOf reports whether xl ⊆ yl.
+func (xl termlist) subsetOf(yl termlist) bool {
+	if yl.isEmpty() {
+		return xl.isEmpty()
+	}
+
+	// each term x of xl must be a subset of yl
+	for _, x := range xl {
+		if !yl.supersetOf(x) {
+			return false // x is not a subset yl
+		}
+	}
+	return true
+}

vendor/golang.org/x/tools/internal/typeparams/typeparams_go117.go

@@ -0,0 +1,197 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !go1.18
+// +build !go1.18
+
+package typeparams
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+)
+
+func unsupported() {
+	panic("type parameters are unsupported at this go version")
+}
+
+// IndexListExpr is a placeholder type, as type parameters are not supported at
+// this Go version. Its methods panic on use.
+type IndexListExpr struct {
+	ast.Expr
+	X       ast.Expr   // expression
+	Lbrack  token.Pos  // position of "["
+	Indices []ast.Expr // index expressions
+	Rbrack  token.Pos  // position of "]"
+}
+
+// ForTypeSpec returns an empty field list, as type parameters on not supported
+// at this Go version.
+func ForTypeSpec(*ast.TypeSpec) *ast.FieldList {
+	return nil
+}
+
+// ForFuncType returns an empty field list, as type parameters are not
+// supported at this Go version.
+func ForFuncType(*ast.FuncType) *ast.FieldList {
+	return nil
+}
+
+// TypeParam is a placeholder type, as type parameters are not supported at
+// this Go version. Its methods panic on use.
+type TypeParam struct{ types.Type }
+
+func (*TypeParam) Index() int             { unsupported(); return 0 }
+func (*TypeParam) Constraint() types.Type { unsupported(); return nil }
+func (*TypeParam) Obj() *types.TypeName   { unsupported(); return nil }
+
+// TypeParamList is a placeholder for an empty type parameter list.
+type TypeParamList struct{}
+
+func (*TypeParamList) Len() int          { return 0 }
+func (*TypeParamList) At(int) *TypeParam { unsupported(); return nil }
+
+// TypeList is a placeholder for an empty type list.
+type TypeList struct{}
+
+func (*TypeList) Len() int          { return 0 }
+func (*TypeList) At(int) types.Type { unsupported(); return nil }
+
+// NewTypeParam is unsupported at this Go version, and panics.
+func NewTypeParam(name *types.TypeName, constraint types.Type) *TypeParam {
+	unsupported()
+	return nil
+}
+
+// SetTypeParamConstraint is unsupported at this Go version, and panics.
+func SetTypeParamConstraint(tparam *TypeParam, constraint types.Type) {
+	unsupported()
+}
+
+// NewSignatureType calls types.NewSignature, panicking if recvTypeParams or
+// typeParams is non-empty.
+func NewSignatureType(recv *types.Var, recvTypeParams, typeParams []*TypeParam, params, results *types.Tuple, variadic bool) *types.Signature {
+	if len(recvTypeParams) != 0 || len(typeParams) != 0 {
+		panic("signatures cannot have type parameters at this Go version")
+	}
+	return types.NewSignature(recv, params, results, variadic)
+}
+
+// ForSignature returns an empty slice.
+func ForSignature(*types.Signature) *TypeParamList {
+	return nil
+}
+
+// RecvTypeParams returns a nil slice.
+func RecvTypeParams(sig *types.Signature) *TypeParamList {
+	return nil
+}
+
+// IsComparable returns false, as no interfaces are type-restricted at this Go
+// version.
+func IsComparable(*types.Interface) bool {
+	return false
+}
+
+// IsMethodSet returns true, as no interfaces are type-restricted at this Go
+// version.
+func IsMethodSet(*types.Interface) bool {
+	return true
+}
+
+// IsImplicit returns false, as no interfaces are implicit at this Go version.
+func IsImplicit(*types.Interface) bool {
+	return false
+}
+
+// MarkImplicit does nothing, because this Go version does not have implicit
+// interfaces.
+func MarkImplicit(*types.Interface) {}
+
+// ForNamed returns an empty type parameter list, as type parameters are not
+// supported at this Go version.
+func ForNamed(*types.Named) *TypeParamList {
+	return nil
+}
+
+// SetForNamed panics if tparams is non-empty.
+func SetForNamed(_ *types.Named, tparams []*TypeParam) {
+	if len(tparams) > 0 {
+		unsupported()
+	}
+}
+
+// NamedTypeArgs returns nil.
+func NamedTypeArgs(*types.Named) *TypeList {
+	return nil
+}
+
+// NamedTypeOrigin is the identity method at this Go version.
+func NamedTypeOrigin(named *types.Named) types.Type {
+	return named
+}
+
+// Term holds information about a structural type restriction.
+type Term struct {
+	tilde bool
+	typ   types.Type
+}
+
+func (m *Term) Tilde() bool      { return m.tilde }
+func (m *Term) Type() types.Type { return m.typ }
+func (m *Term) String() string {
+	pre := ""
+	if m.tilde {
+		pre = "~"
+	}
+	return pre + m.typ.String()
+}
+
+// NewTerm is unsupported at this Go version, and panics.
+func NewTerm(tilde bool, typ types.Type) *Term {
+	return &Term{tilde, typ}
+}
+
+// Union is a placeholder type, as type parameters are not supported at this Go
+// version. Its methods panic on use.
+type Union struct{ types.Type }
+
+func (*Union) Len() int         { return 0 }
+func (*Union) Term(i int) *Term { unsupported(); return nil }
+
+// NewUnion is unsupported at this Go version, and panics.
+func NewUnion(terms []*Term) *Union {
+	unsupported()
+	return nil
+}
+
+// InitInstanceInfo is a noop at this Go version.
+func InitInstanceInfo(*types.Info) {}
+
+// Instance is a placeholder type, as type parameters are not supported at this
+// Go version.
+type Instance struct {
+	TypeArgs *TypeList
+	Type     types.Type
+}
+
+// GetInstances returns a nil map, as type parameters are not supported at this
+// Go version.
+func GetInstances(info *types.Info) map[*ast.Ident]Instance { return nil }
+
+// Context is a placeholder type, as type parameters are not supported at
+// this Go version.
+type Context struct{}
+
+// NewContext returns a placeholder Context instance.
+func NewContext() *Context {
+	return &Context{}
+}
+
+// Instantiate is unsupported on this Go version, and panics.
+func Instantiate(ctxt *Context, typ types.Type, targs []types.Type, validate bool) (types.Type, error) {
+	unsupported()
+	return nil, nil
+}

vendor/golang.org/x/tools/internal/typeparams/typeparams_go118.go

@@ -0,0 +1,151 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.18
+// +build go1.18
+
+package typeparams
+
+import (
+	"go/ast"
+	"go/types"
+)
+
+// IndexListExpr is an alias for ast.IndexListExpr.
+type IndexListExpr = ast.IndexListExpr
+
+// ForTypeSpec returns n.TypeParams.
+func ForTypeSpec(n *ast.TypeSpec) *ast.FieldList {
+	if n == nil {
+		return nil
+	}
+	return n.TypeParams
+}
+
+// ForFuncType returns n.TypeParams.
+func ForFuncType(n *ast.FuncType) *ast.FieldList {
+	if n == nil {
+		return nil
+	}
+	return n.TypeParams
+}
+
+// TypeParam is an alias for types.TypeParam
+type TypeParam = types.TypeParam
+
+// TypeParamList is an alias for types.TypeParamList
+type TypeParamList = types.TypeParamList
+
+// TypeList is an alias for types.TypeList
+type TypeList = types.TypeList
+
+// NewTypeParam calls types.NewTypeParam.
+func NewTypeParam(name *types.TypeName, constraint types.Type) *TypeParam {
+	return types.NewTypeParam(name, constraint)
+}
+
+// SetTypeParamConstraint calls tparam.SetConstraint(constraint).
+func SetTypeParamConstraint(tparam *TypeParam, constraint types.Type) {
+	tparam.SetConstraint(constraint)
+}
+
+// NewSignatureType calls types.NewSignatureType.
+func NewSignatureType(recv *types.Var, recvTypeParams, typeParams []*TypeParam, params, results *types.Tuple, variadic bool) *types.Signature {
+	return types.NewSignatureType(recv, recvTypeParams, typeParams, params, results, variadic)
+}
+
+// ForSignature returns sig.TypeParams()
+func ForSignature(sig *types.Signature) *TypeParamList {
+	return sig.TypeParams()
+}
+
+// RecvTypeParams returns sig.RecvTypeParams().
+func RecvTypeParams(sig *types.Signature) *TypeParamList {
+	return sig.RecvTypeParams()
+}
+
+// IsComparable calls iface.IsComparable().
+func IsComparable(iface *types.Interface) bool {
+	return iface.IsComparable()
+}
+
+// IsMethodSet calls iface.IsMethodSet().
+func IsMethodSet(iface *types.Interface) bool {
+	return iface.IsMethodSet()
+}
+
+// IsImplicit calls iface.IsImplicit().
+func IsImplicit(iface *types.Interface) bool {
+	return iface.IsImplicit()
+}
+
+// MarkImplicit calls iface.MarkImplicit().
+func MarkImplicit(iface *types.Interface) {
+	iface.MarkImplicit()
+}
+
+// ForNamed extracts the (possibly empty) type parameter object list from
+// named.
+func ForNamed(named *types.Named) *TypeParamList {
+	return named.TypeParams()
+}
+
+// SetForNamed sets the type params tparams on n. Each tparam must be of
+// dynamic type *types.TypeParam.
+func SetForNamed(n *types.Named, tparams []*TypeParam) {
+	n.SetTypeParams(tparams)
+}
+
+// NamedTypeArgs returns named.TypeArgs().
+func NamedTypeArgs(named *types.Named) *TypeList {
+	return named.TypeArgs()
+}
+
+// NamedTypeOrigin returns named.Orig().
+func NamedTypeOrigin(named *types.Named) types.Type {
+	return named.Origin()
+}
+
+// Term is an alias for types.Term.
+type Term = types.Term
+
+// NewTerm calls types.NewTerm.
+func NewTerm(tilde bool, typ types.Type) *Term {
+	return types.NewTerm(tilde, typ)
+}
+
+// Union is an alias for types.Union
+type Union = types.Union
+
+// NewUnion calls types.NewUnion.
+func NewUnion(terms []*Term) *Union {
+	return types.NewUnion(terms)
+}
+
+// InitInstanceInfo initializes info to record information about type and
+// function instances.
+func InitInstanceInfo(info *types.Info) {
+	info.Instances = make(map[*ast.Ident]types.Instance)
+}
+
+// Instance is an alias for types.Instance.
+type Instance = types.Instance
+
+// GetInstances returns info.Instances.
+func GetInstances(info *types.Info) map[*ast.Ident]Instance {
+	return info.Instances
+}
+
+// Context is an alias for types.Context.
+type Context = types.Context
+
+// NewContext calls types.NewContext.
+func NewContext() *Context {
+	return types.NewContext()
+}
+
+// Instantiate calls types.Instantiate.
+func Instantiate(ctxt *Context, typ types.Type, targs []types.Type, validate bool) (types.Type, error) {
+	return types.Instantiate(ctxt, typ, targs, validate)
+}

vendor/golang.org/x/tools/internal/typeparams/typeterm.go

@@ -0,0 +1,170 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by copytermlist.go DO NOT EDIT.
+
+package typeparams
+
+import "go/types"
+
+// A term describes elementary type sets:
+//
+//   ∅:  (*term)(nil)     == ∅                      // set of no types (empty set)
+//   𝓤:  &term{}          == 𝓤                      // set of all types (𝓤niverse)
+//   T:  &term{false, T}  == {T}                    // set of type T
+//  ~t:  &term{true, t}   == {t' | under(t') == t}  // set of types with underlying type t
+//
+type term struct {
+	tilde bool // valid if typ != nil
+	typ   types.Type
+}
+
+func (x *term) String() string {
+	switch {
+	case x == nil:
+		return "∅"
+	case x.typ == nil:
+		return "𝓤"
+	case x.tilde:
+		return "~" + x.typ.String()
+	default:
+		return x.typ.String()
+	}
+}
+
+// equal reports whether x and y represent the same type set.
+func (x *term) equal(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return x == y
+	case x.typ == nil || y.typ == nil:
+		return x.typ == y.typ
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	return x.tilde == y.tilde && types.Identical(x.typ, y.typ)
+}
+
+// union returns the union x ∪ y: zero, one, or two non-nil terms.
+func (x *term) union(y *term) (_, _ *term) {
+	// easy cases
+	switch {
+	case x == nil && y == nil:
+		return nil, nil // ∅ ∪ ∅ == ∅
+	case x == nil:
+		return y, nil // ∅ ∪ y == y
+	case y == nil:
+		return x, nil // x ∪ ∅ == x
+	case x.typ == nil:
+		return x, nil // 𝓤 ∪ y == 𝓤
+	case y.typ == nil:
+		return y, nil // x ∪ 𝓤 == 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∪ ~t == ~t
+	// ~t ∪  T == ~t
+	//  T ∪ ~t == ~t
+	//  T ∪  T ==  T
+	if x.tilde || !y.tilde {
+		return x, nil
+	}
+	return y, nil
+}
+
+// intersect returns the intersection x ∩ y.
+func (x *term) intersect(y *term) *term {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
+	case x.typ == nil:
+		return y // 𝓤 ∩ y == y
+	case y.typ == nil:
+		return x // x ∩ 𝓤 == x
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return nil // x ∩ y == ∅ if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∩ ~t == ~t
+	// ~t ∩  T ==  T
+	//  T ∩ ~t ==  T
+	//  T ∩  T ==  T
+	if !x.tilde || y.tilde {
+		return x
+	}
+	return y
+}
+
+// includes reports whether t ∈ x.
+func (x *term) includes(t types.Type) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return false // t ∈ ∅ == false
+	case x.typ == nil:
+		return true // t ∈ 𝓤 == true
+	}
+	// ∅ ⊂ x ⊂ 𝓤
+
+	u := t
+	if x.tilde {
+		u = under(u)
+	}
+	return types.Identical(x.typ, u)
+}
+
+// subsetOf reports whether x ⊆ y.
+func (x *term) subsetOf(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return true // ∅ ⊆ y == true
+	case y == nil:
+		return false // x ⊆ ∅ == false since x != ∅
+	case y.typ == nil:
+		return true // x ⊆ 𝓤 == true
+	case x.typ == nil:
+		return false // 𝓤 ⊆ y == false since y != 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return false // x ⊆ y == false if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ⊆ ~t == true
+	// ~t ⊆ T == false
+	//  T ⊆ ~t == true
+	//  T ⊆  T == true
+	return !x.tilde || y.tilde
+}
+
+// disjoint reports whether x ∩ y == ∅.
+// x.typ and y.typ must not be nil.
+func (x *term) disjoint(y *term) bool {
+	if debug && (x.typ == nil || y.typ == nil) {
+		panic("invalid argument(s)")
+	}
+	ux := x.typ
+	if y.tilde {
+		ux = under(ux)
+	}
+	uy := y.typ
+	if x.tilde {
+		uy = under(uy)
+	}
+	return !types.Identical(ux, uy)
+}

vendor/golang.org/x/tools/internal/typesinternal/errorcode_string.go

@@ -0,0 +1,167 @@
+// Code generated by "stringer -type=ErrorCode"; DO NOT EDIT.
+
+package typesinternal
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[Test-1]
+	_ = x[BlankPkgName-2]
+	_ = x[MismatchedPkgName-3]
+	_ = x[InvalidPkgUse-4]
+	_ = x[BadImportPath-5]
+	_ = x[BrokenImport-6]
+	_ = x[ImportCRenamed-7]
+	_ = x[UnusedImport-8]
+	_ = x[InvalidInitCycle-9]
+	_ = x[DuplicateDecl-10]
+	_ = x[InvalidDeclCycle-11]
+	_ = x[InvalidTypeCycle-12]
+	_ = x[InvalidConstInit-13]
+	_ = x[InvalidConstVal-14]
+	_ = x[InvalidConstType-15]
+	_ = x[UntypedNil-16]
+	_ = x[WrongAssignCount-17]
+	_ = x[UnassignableOperand-18]
+	_ = x[NoNewVar-19]
+	_ = x[MultiValAssignOp-20]
+	_ = x[InvalidIfaceAssign-21]
+	_ = x[InvalidChanAssign-22]
+	_ = x[IncompatibleAssign-23]
+	_ = x[UnaddressableFieldAssign-24]
+	_ = x[NotAType-25]
+	_ = x[InvalidArrayLen-26]
+	_ = x[BlankIfaceMethod-27]
+	_ = x[IncomparableMapKey-28]
+	_ = x[InvalidIfaceEmbed-29]
+	_ = x[InvalidPtrEmbed-30]
+	_ = x[BadRecv-31]
+	_ = x[InvalidRecv-32]
+	_ = x[DuplicateFieldAndMethod-33]
+	_ = x[DuplicateMethod-34]
+	_ = x[InvalidBlank-35]
+	_ = x[InvalidIota-36]
+	_ = x[MissingInitBody-37]
+	_ = x[InvalidInitSig-38]
+	_ = x[InvalidInitDecl-39]
+	_ = x[InvalidMainDecl-40]
+	_ = x[TooManyValues-41]
+	_ = x[NotAnExpr-42]
+	_ = x[TruncatedFloat-43]
+	_ = x[NumericOverflow-44]
+	_ = x[UndefinedOp-45]
+	_ = x[MismatchedTypes-46]
+	_ = x[DivByZero-47]
+	_ = x[NonNumericIncDec-48]
+	_ = x[UnaddressableOperand-49]
+	_ = x[InvalidIndirection-50]
+	_ = x[NonIndexableOperand-51]
+	_ = x[InvalidIndex-52]
+	_ = x[SwappedSliceIndices-53]
+	_ = x[NonSliceableOperand-54]
+	_ = x[InvalidSliceExpr-55]
+	_ = x[InvalidShiftCount-56]
+	_ = x[InvalidShiftOperand-57]
+	_ = x[InvalidReceive-58]
+	_ = x[InvalidSend-59]
+	_ = x[DuplicateLitKey-60]
+	_ = x[MissingLitKey-61]
+	_ = x[InvalidLitIndex-62]
+	_ = x[OversizeArrayLit-63]
+	_ = x[MixedStructLit-64]
+	_ = x[InvalidStructLit-65]
+	_ = x[MissingLitField-66]
+	_ = x[DuplicateLitField-67]
+	_ = x[UnexportedLitField-68]
+	_ = x[InvalidLitField-69]
+	_ = x[UntypedLit-70]
+	_ = x[InvalidLit-71]
+	_ = x[AmbiguousSelector-72]
+	_ = x[UndeclaredImportedName-73]
+	_ = x[UnexportedName-74]
+	_ = x[UndeclaredName-75]
+	_ = x[MissingFieldOrMethod-76]
+	_ = x[BadDotDotDotSyntax-77]
+	_ = x[NonVariadicDotDotDot-78]
+	_ = x[MisplacedDotDotDot-79]
+	_ = x[InvalidDotDotDotOperand-80]
+	_ = x[InvalidDotDotDot-81]
+	_ = x[UncalledBuiltin-82]
+	_ = x[InvalidAppend-83]
+	_ = x[InvalidCap-84]
+	_ = x[InvalidClose-85]
+	_ = x[InvalidCopy-86]
+	_ = x[InvalidComplex-87]
+	_ = x[InvalidDelete-88]
+	_ = x[InvalidImag-89]
+	_ = x[InvalidLen-90]
+	_ = x[SwappedMakeArgs-91]
+	_ = x[InvalidMake-92]
+	_ = x[InvalidReal-93]
+	_ = x[InvalidAssert-94]
+	_ = x[ImpossibleAssert-95]
+	_ = x[InvalidConversion-96]
+	_ = x[InvalidUntypedConversion-97]
+	_ = x[BadOffsetofSyntax-98]
+	_ = x[InvalidOffsetof-99]
+	_ = x[UnusedExpr-100]
+	_ = x[UnusedVar-101]
+	_ = x[MissingReturn-102]
+	_ = x[WrongResultCount-103]
+	_ = x[OutOfScopeResult-104]
+	_ = x[InvalidCond-105]
+	_ = x[InvalidPostDecl-106]
+	_ = x[InvalidChanRange-107]
+	_ = x[InvalidIterVar-108]
+	_ = x[InvalidRangeExpr-109]
+	_ = x[MisplacedBreak-110]
+	_ = x[MisplacedContinue-111]
+	_ = x[MisplacedFallthrough-112]
+	_ = x[DuplicateCase-113]
+	_ = x[DuplicateDefault-114]
+	_ = x[BadTypeKeyword-115]
+	_ = x[InvalidTypeSwitch-116]
+	_ = x[InvalidExprSwitch-117]
+	_ = x[InvalidSelectCase-118]
+	_ = x[UndeclaredLabel-119]
+	_ = x[DuplicateLabel-120]
+	_ = x[MisplacedLabel-121]
+	_ = x[UnusedLabel-122]
+	_ = x[JumpOverDecl-123]
+	_ = x[JumpIntoBlock-124]
+	_ = x[InvalidMethodExpr-125]
+	_ = x[WrongArgCount-126]
+	_ = x[InvalidCall-127]
+	_ = x[UnusedResults-128]
+	_ = x[InvalidDefer-129]
+	_ = x[InvalidGo-130]
+	_ = x[BadDecl-131]
+	_ = x[RepeatedDecl-132]
+	_ = x[InvalidUnsafeAdd-133]
+	_ = x[InvalidUnsafeSlice-134]
+	_ = x[UnsupportedFeature-135]
+	_ = x[NotAGenericType-136]
+	_ = x[WrongTypeArgCount-137]
+	_ = x[CannotInferTypeArgs-138]
+	_ = x[InvalidTypeArg-139]
+	_ = x[InvalidInstanceCycle-140]
+	_ = x[InvalidUnion-141]
+	_ = x[MisplacedConstraintIface-142]
+	_ = x[InvalidMethodTypeParams-143]
+	_ = x[MisplacedTypeParam-144]
+}
+
+const _ErrorCode_name = "TestBlankPkgNameMismatchedPkgNameInvalidPkgUseBadImportPathBrokenImportImportCRenamedUnusedImportInvalidInitCycleDuplicateDeclInvalidDeclCycleInvalidTypeCycleInvalidConstInitInvalidConstValInvalidConstTypeUntypedNilWrongAssignCountUnassignableOperandNoNewVarMultiValAssignOpInvalidIfaceAssignInvalidChanAssignIncompatibleAssignUnaddressableFieldAssignNotATypeInvalidArrayLenBlankIfaceMethodIncomparableMapKeyInvalidIfaceEmbedInvalidPtrEmbedBadRecvInvalidRecvDuplicateFieldAndMethodDuplicateMethodInvalidBlankInvalidIotaMissingInitBodyInvalidInitSigInvalidInitDeclInvalidMainDeclTooManyValuesNotAnExprTruncatedFloatNumericOverflowUndefinedOpMismatchedTypesDivByZeroNonNumericIncDecUnaddressableOperandInvalidIndirectionNonIndexableOperandInvalidIndexSwappedSliceIndicesNonSliceableOperandInvalidSliceExprInvalidShiftCountInvalidShiftOperandInvalidReceiveInvalidSendDuplicateLitKeyMissingLitKeyInvalidLitIndexOversizeArrayLitMixedStructLitInvalidStructLitMissingLitFieldDuplicateLitFieldUnexportedLitFieldInvalidLitFieldUntypedLitInvalidLitAmbiguousSelectorUndeclaredImportedNameUnexportedNameUndeclaredNameMissingFieldOrMethodBadDotDotDotSyntaxNonVariadicDotDotDotMisplacedDotDotDotInvalidDotDotDotOperandInvalidDotDotDotUncalledBuiltinInvalidAppendInvalidCapInvalidCloseInvalidCopyInvalidComplexInvalidDeleteInvalidImagInvalidLenSwappedMakeArgsInvalidMakeInvalidRealInvalidAssertImpossibleAssertInvalidConversionInvalidUntypedConversionBadOffsetofSyntaxInvalidOffsetofUnusedExprUnusedVarMissingReturnWrongResultCountOutOfScopeResultInvalidCondInvalidPostDeclInvalidChanRangeInvalidIterVarInvalidRangeExprMisplacedBreakMisplacedContinueMisplacedFallthroughDuplicateCaseDuplicateDefaultBadTypeKeywordInvalidTypeSwitchInvalidExprSwitchInvalidSelectCaseUndeclaredLabelDuplicateLabelMisplacedLabelUnusedLabelJumpOverDeclJumpIntoBlockInvalidMethodExprWrongArgCountInvalidCallUnusedResultsInvalidDeferInvalidGoBadDeclRepeatedDeclInvalidUnsafeAddInvalidUnsafeSliceUnsupportedFeatureNotAGenericTypeWrongTypeArgCountCannotInferTypeArgsInvalidTypeArgInvalidInstanceCycleInvalidUnionMisplacedConstraintIfaceInvalidMethodTypeParamsMisplacedTypeParam"
+
+var _ErrorCode_index = [...]uint16{0, 4, 16, 33, 46, 59, 71, 85, 97, 113, 126, 142, 158, 174, 189, 205, 215, 231, 250, 258, 274, 292, 309, 327, 351, 359, 374, 390, 408, 425, 440, 447, 458, 481, 496, 508, 519, 534, 548, 563, 578, 591, 600, 614, 629, 640, 655, 664, 680, 700, 718, 737, 749, 768, 787, 803, 820, 839, 853, 864, 879, 892, 907, 923, 937, 953, 968, 985, 1003, 1018, 1028, 1038, 1055, 1077, 1091, 1105, 1125, 1143, 1163, 1181, 1204, 1220, 1235, 1248, 1258, 1270, 1281, 1295, 1308, 1319, 1329, 1344, 1355, 1366, 1379, 1395, 1412, 1436, 1453, 1468, 1478, 1487, 1500, 1516, 1532, 1543, 1558, 1574, 1588, 1604, 1618, 1635, 1655, 1668, 1684, 1698, 1715, 1732, 1749, 1764, 1778, 1792, 1803, 1815, 1828, 1845, 1858, 1869, 1882, 1894, 1903, 1910, 1922, 1938, 1956, 1974, 1989, 2006, 2025, 2039, 2059, 2071, 2095, 2118, 2136}
+
+func (i ErrorCode) String() string {
+	i -= 1
+	if i < 0 || i >= ErrorCode(len(_ErrorCode_index)-1) {
+		return "ErrorCode(" + strconv.FormatInt(int64(i+1), 10) + ")"
+	}
+	return _ErrorCode_name[_ErrorCode_index[i]:_ErrorCode_index[i+1]]
+}

vendor/golang.org/x/tools/internal/typesinternal/types.go

@@ -0,0 +1,52 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package typesinternal provides access to internal go/types APIs that are not
+// yet exported.
+package typesinternal
+
+import (
+	"go/token"
+	"go/types"
+	"reflect"
+	"unsafe"
+)
+
+func SetUsesCgo(conf *types.Config) bool {
+	v := reflect.ValueOf(conf).Elem()
+
+	f := v.FieldByName("go115UsesCgo")
+	if !f.IsValid() {
+		f = v.FieldByName("UsesCgo")
+		if !f.IsValid() {
+			return false
+		}
+	}
+
+	addr := unsafe.Pointer(f.UnsafeAddr())
+	*(*bool)(addr) = true
+
+	return true
+}
+
+// ReadGo116ErrorData extracts additional information from types.Error values
+// generated by Go version 1.16 and later: the error code, start position, and
+// end position. If all positions are valid, start <= err.Pos <= end.
+//
+// If the data could not be read, the final result parameter will be false.
+func ReadGo116ErrorData(err types.Error) (code ErrorCode, start, end token.Pos, ok bool) {
+	var data [3]int
+	// By coincidence all of these fields are ints, which simplifies things.
+	v := reflect.ValueOf(err)
+	for i, name := range []string{"go116code", "go116start", "go116end"} {
+		f := v.FieldByName(name)
+		if !f.IsValid() {
+			return 0, 0, 0, false
+		}
+		data[i] = int(f.Int())
+	}
+	return ErrorCode(data[0]), token.Pos(data[1]), token.Pos(data[2]), true
+}
+
+var SetGoVersion = func(conf *types.Config, version string) bool { return false }

vendor/golang.org/x/tools/internal/typesinternal/types_118.go

@@ -0,0 +1,19 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.18
+// +build go1.18
+
+package typesinternal
+
+import (
+	"go/types"
+)
+
+func init() {
+	SetGoVersion = func(conf *types.Config, version string) bool {
+		conf.GoVersion = version
+		return true
+	}
+}