Update dependencies

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

@@ -0,0 +1,186 @@
+// 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"
+	"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.Output()
+	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
+	}
+}
+
+// readAll works the same way as io.ReadAll, but avoids allocations and copies
+// by preallocating a byte slice of the necessary size if the size is known up
+// front. This is always possible when the input is an archive. In that case,
+// NewReader will return the known size using an io.LimitedReader.
+func readAll(r io.Reader) ([]byte, error) {
+	if lr, ok := r.(*io.LimitedReader); ok {
+		data := make([]byte, lr.N)
+		_, err := io.ReadFull(lr, data)
+		return data, err
+	}
+	return io.ReadAll(r)
+}
+
+// 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 := 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 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 'v', 'c', 'd': // binary, till go1.10
+			return nil, fmt.Errorf("binary (%c) import format is no longer supported", data[0])
+
+		case 'i': // indexed, till go1.19
+			_, pkg, err := gcimporter.IImportData(fset, imports, data[1:], path)
+			return pkg, err
+
+		case 'u': // unified, from go1.20
+			_, 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 := 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/packages/doc.go

@@ -0,0 +1,242 @@
+// 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 returns a
+list of [Package] values describing individual packages matched by those
+patterns.
+A [Config] specifies configuration options, the most important of which is
+the [LoadMode], which controls the amount of detail in the loaded packages.
+
+Load passes most patterns directly to the underlying build tool.
+The default build tool is the go command.
+Its supported patterns are described at
+https://pkg.go.dev/cmd/go#hdr-Package_lists_and_patterns.
+Other build systems may be supported by providing a "driver";
+see [The driver protocol].
+
+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
+  - TypesInfo, 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 [Load], so that it can interpret them
+according to the conventions of the underlying build system.
+
+See the Example function for typical usage.
+
+# The driver protocol
+
+[Load] may be used to load Go packages even in Go projects that use
+alternative build systems, by installing an appropriate "driver"
+program for the build system and specifying its location in the
+GOPACKAGESDRIVER environment variable.
+For example,
+https://github.com/bazelbuild/rules_go/wiki/Editor-and-tool-integration
+explains how to use the driver for Bazel.
+
+The driver program is responsible for interpreting patterns in its
+preferred notation and reporting information about the packages that
+those patterns identify. Drivers must also support the special "file="
+and "pattern=" patterns described above.
+
+The patterns are provided as positional command-line arguments. A
+JSON-encoded [DriverRequest] message providing additional information
+is written to the driver's standard input. The driver must write a
+JSON-encoded [DriverResponse] message to its standard output. (This
+message differs from the JSON schema produced by 'go list'.)
+*/
+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.
+
+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 +1,156 @@
+// 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
+
+// This file defines the protocol that enables an external "driver"
+// tool to supply package metadata in place of 'go list'.
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+// DriverRequest defines the schema of a request for package metadata
+// from an external driver program. The JSON-encoded DriverRequest
+// message is provided to the driver program's standard input. The
+// query patterns are provided as command-line arguments.
+//
+// See the package documentation for an overview.
+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 contents of overlay files (see Config.Overlay).
+	Overlay map[string][]byte `json:"overlay"`
+}
+
+// DriverResponse defines the schema of a response from an external
+// driver program, providing the results of a query for package
+// metadata. The driver program must write a JSON-encoded
+// DriverResponse message to its standard output.
+//
+// See the package documentation for an overview.
+type DriverResponse struct {
+	// NotHandled is returned if the request can't be handled by the current
+	// driver. If an external driver returns a response with NotHandled, the
+	// rest of the DriverResponse is ignored, and go/packages will fallback
+	// to the next driver. If go/packages is extended in the future to support
+	// lists of multiple drivers, go/packages will fall back to the next driver.
+	NotHandled bool
+
+	// Compiler and Arch are the arguments pass of types.SizesFor
+	// to get a types.Sizes to use when type checking.
+	Compiler string
+	Arch     string
+
+	// Roots is the set of package IDs that make up the root packages.
+	// We have to encode this separately because when we encode a single package
+	// we cannot know if it is one of the roots as that requires knowledge of the
+	// graph it is part of.
+	Roots []string `json:",omitempty"`
+
+	// Packages is the full set of packages in the graph.
+	// The packages are not connected into a graph.
+	// The Imports if populated will be stubs that only have their ID set.
+	// Imports will be connected and then type and syntax information added in a
+	// later pass (see refine).
+	Packages []*Package
+
+	// GoVersion is the minor version number used by the driver
+	// (e.g. the go command on the PATH) when selecting .go files.
+	// Zero means unknown.
+	GoVersion int
+}
+
+// driver is the type for functions that query the build system for the
+// packages named by the patterns.
+type driver func(cfg *Config, patterns ...string) (*DriverResponse, error)
+
+// 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
+		// The cwd gets resolved to the real path. On Darwin, where
+		// /tmp is a symlink, this breaks anything that expects the
+		// working directory to keep the original path, including the
+		// go command when dealing with modules.
+		//
+		// os.Getwd 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.
+		//
+		// (See similar trick in Invocation.run in ../../internal/gocommand/invoke.go)
+		cmd.Env = append(slicesClip(cfg.Env), "PWD="+cfg.Dir)
+		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
+	}
+}
+
+// slicesClip removes unused capacity from the slice, returning s[:len(s):len(s)].
+// TODO(adonovan): use go1.21 slices.Clip.
+func slicesClip[S ~[]E, E any](s S) S { return s[:len(s):len(s)] }

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

@@ -0,0 +1,83 @@
+// 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"
+	"path/filepath"
+
+	"golang.org/x/tools/internal/gocommand"
+)
+
+// 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
+}

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/go/types/objectpath/objectpath.go

@@ -0,0 +1,772 @@
+// 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 objectpath defines a naming scheme for types.Objects
+// (that is, named entities in Go programs) relative to their enclosing
+// package.
+//
+// Type-checker objects are canonical, so they are usually identified by
+// their address in memory (a pointer), but a pointer has meaning only
+// within one address space. By contrast, objectpath names allow the
+// identity of an object to be sent from one program to another,
+// establishing a correspondence between types.Object variables that are
+// distinct but logically equivalent.
+//
+// A single object may have multiple paths. In this example,
+//
+//	type A struct{ X int }
+//	type B A
+//
+// the field X has two paths due to its membership of both A and B.
+// The For(obj) function always returns one of these paths, arbitrarily
+// but consistently.
+package objectpath
+
+import (
+	"fmt"
+	"go/types"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/internal/aliases"
+	"golang.org/x/tools/internal/typesinternal"
+)
+
+// TODO(adonovan): think about generic aliases.
+
+// A Path is an opaque name that identifies a types.Object
+// relative to its package. Conceptually, the name consists of a
+// sequence of destructuring operations applied to the package scope
+// to obtain the original object.
+// The name does not include the package itself.
+type Path string
+
+// Encoding
+//
+// An object path is a textual and (with training) human-readable encoding
+// of a sequence of destructuring operators, starting from a types.Package.
+// The sequences represent a path through the package/object/type graph.
+// We classify these operators by their type:
+//
+//	PO package->object	Package.Scope.Lookup
+//	OT  object->type 	Object.Type
+//	TT    type->type 	Type.{Elem,Key,{,{,Recv}Type}Params,Results,Underlying} [EKPRUTrC]
+//	TO   type->object	Type.{At,Field,Method,Obj} [AFMO]
+//
+// All valid paths start with a package and end at an object
+// and thus may be defined by the regular language:
+//
+//	objectpath = PO (OT TT* TO)*
+//
+// The concrete encoding follows directly:
+//   - The only PO operator is Package.Scope.Lookup, which requires an identifier.
+//   - The only OT operator is Object.Type,
+//     which we encode as '.' because dot cannot appear in an identifier.
+//   - The TT operators are encoded as [EKPRUTrC];
+//     two of these ({,Recv}TypeParams) require an integer operand,
+//     which is encoded as a string of decimal digits.
+//   - The TO operators are encoded as [AFMO];
+//     three of these (At,Field,Method) require an integer operand,
+//     which is encoded as a string of decimal digits.
+//     These indices are stable across different representations
+//     of the same package, even source and export data.
+//     The indices used are implementation specific and may not correspond to
+//     the argument to the go/types function.
+//
+// In the example below,
+//
+//	package p
+//
+//	type T interface {
+//		f() (a string, b struct{ X int })
+//	}
+//
+// field X has the path "T.UM0.RA1.F0",
+// representing the following sequence of operations:
+//
+//	p.Lookup("T")					T
+//	.Type().Underlying().Method(0).			f
+//	.Type().Results().At(1)				b
+//	.Type().Field(0)					X
+//
+// The encoding is not maximally compact---every R or P is
+// followed by an A, for example---but this simplifies the
+// encoder and decoder.
+const (
+	// object->type operators
+	opType = '.' // .Type()		  (Object)
+
+	// type->type operators
+	opElem          = 'E' // .Elem()		(Pointer, Slice, Array, Chan, Map)
+	opKey           = 'K' // .Key()			(Map)
+	opParams        = 'P' // .Params()		(Signature)
+	opResults       = 'R' // .Results()		(Signature)
+	opUnderlying    = 'U' // .Underlying()		(Named)
+	opTypeParam     = 'T' // .TypeParams.At(i)	(Named, Signature)
+	opRecvTypeParam = 'r' // .RecvTypeParams.At(i)	(Signature)
+	opConstraint    = 'C' // .Constraint()		(TypeParam)
+
+	// type->object operators
+	opAt     = 'A' // .At(i)	(Tuple)
+	opField  = 'F' // .Field(i)	(Struct)
+	opMethod = 'M' // .Method(i)	(Named or Interface; not Struct: "promoted" names are ignored)
+	opObj    = 'O' // .Obj()	(Named, TypeParam)
+)
+
+// For is equivalent to new(Encoder).For(obj).
+//
+// It may be more efficient to reuse a single Encoder across several calls.
+func For(obj types.Object) (Path, error) {
+	return new(Encoder).For(obj)
+}
+
+// An Encoder amortizes the cost of encoding the paths of multiple objects.
+// The zero value of an Encoder is ready to use.
+type Encoder struct {
+	scopeMemo map[*types.Scope][]types.Object // memoization of scopeObjects
+}
+
+// For returns the path to an object relative to its package,
+// or an error if the object is not accessible from the package's Scope.
+//
+// The For function guarantees to return a path only for the following objects:
+// - package-level types
+// - exported package-level non-types
+// - methods
+// - parameter and result variables
+// - struct fields
+// These objects are sufficient to define the API of their package.
+// The objects described by a package's export data are drawn from this set.
+//
+// The set of objects accessible from a package's Scope depends on
+// whether the package was produced by type-checking syntax, or
+// reading export data; the latter may have a smaller Scope since
+// export data trims objects that are not reachable from an exported
+// declaration. For example, the For function will return a path for
+// an exported method of an unexported type that is not reachable
+// from any public declaration; this path will cause the Object
+// function to fail if called on a package loaded from export data.
+// TODO(adonovan): is this a bug or feature? Should this package
+// compute accessibility in the same way?
+//
+// For does not return a path for predeclared names, imported package
+// names, local names, and unexported package-level names (except
+// types).
+//
+// Example: given this definition,
+//
+//	package p
+//
+//	type T interface {
+//		f() (a string, b struct{ X int })
+//	}
+//
+// For(X) would return a path that denotes the following sequence of operations:
+//
+//	p.Scope().Lookup("T")				(TypeName T)
+//	.Type().Underlying().Method(0).			(method Func f)
+//	.Type().Results().At(1)				(field Var b)
+//	.Type().Field(0)					(field Var X)
+//
+// where p is the package (*types.Package) to which X belongs.
+func (enc *Encoder) For(obj types.Object) (Path, error) {
+	pkg := obj.Pkg()
+
+	// This table lists the cases of interest.
+	//
+	// Object				Action
+	// ------                               ------
+	// nil					reject
+	// builtin				reject
+	// pkgname				reject
+	// label				reject
+	// var
+	//    package-level			accept
+	//    func param/result			accept
+	//    local				reject
+	//    struct field			accept
+	// const
+	//    package-level			accept
+	//    local				reject
+	// func
+	//    package-level			accept
+	//    init functions			reject
+	//    concrete method			accept
+	//    interface method			accept
+	// type
+	//    package-level			accept
+	//    local				reject
+	//
+	// The only accessible package-level objects are members of pkg itself.
+	//
+	// The cases are handled in four steps:
+	//
+	// 1. reject nil and builtin
+	// 2. accept package-level objects
+	// 3. reject obviously invalid objects
+	// 4. search the API for the path to the param/result/field/method.
+
+	// 1. reference to nil or builtin?
+	if pkg == nil {
+		return "", fmt.Errorf("predeclared %s has no path", obj)
+	}
+	scope := pkg.Scope()
+
+	// 2. package-level object?
+	if scope.Lookup(obj.Name()) == obj {
+		// Only exported objects (and non-exported types) have a path.
+		// Non-exported types may be referenced by other objects.
+		if _, ok := obj.(*types.TypeName); !ok && !obj.Exported() {
+			return "", fmt.Errorf("no path for non-exported %v", obj)
+		}
+		return Path(obj.Name()), nil
+	}
+
+	// 3. Not a package-level object.
+	//    Reject obviously non-viable cases.
+	switch obj := obj.(type) {
+	case *types.TypeName:
+		if _, ok := aliases.Unalias(obj.Type()).(*types.TypeParam); !ok {
+			// With the exception of type parameters, only package-level type names
+			// have a path.
+			return "", fmt.Errorf("no path for %v", obj)
+		}
+	case *types.Const, // Only package-level constants have a path.
+		*types.Label,   // Labels are function-local.
+		*types.PkgName: // PkgNames are file-local.
+		return "", fmt.Errorf("no path for %v", obj)
+
+	case *types.Var:
+		// Could be:
+		// - a field (obj.IsField())
+		// - a func parameter or result
+		// - a local var.
+		// Sadly there is no way to distinguish
+		// a param/result from a local
+		// so we must proceed to the find.
+
+	case *types.Func:
+		// A func, if not package-level, must be a method.
+		if recv := obj.Type().(*types.Signature).Recv(); recv == nil {
+			return "", fmt.Errorf("func is not a method: %v", obj)
+		}
+
+		if path, ok := enc.concreteMethod(obj); ok {
+			// Fast path for concrete methods that avoids looping over scope.
+			return path, nil
+		}
+
+	default:
+		panic(obj)
+	}
+
+	// 4. Search the API for the path to the var (field/param/result) or method.
+
+	// First inspect package-level named types.
+	// In the presence of path aliases, these give
+	// the best paths because non-types may
+	// refer to types, but not the reverse.
+	empty := make([]byte, 0, 48) // initial space
+	objs := enc.scopeObjects(scope)
+	for _, o := range objs {
+		tname, ok := o.(*types.TypeName)
+		if !ok {
+			continue // handle non-types in second pass
+		}
+
+		path := append(empty, o.Name()...)
+		path = append(path, opType)
+
+		T := o.Type()
+
+		if tname.IsAlias() {
+			// type alias
+			if r := find(obj, T, path, nil); r != nil {
+				return Path(r), nil
+			}
+		} else {
+			if named, _ := T.(*types.Named); named != nil {
+				if r := findTypeParam(obj, named.TypeParams(), path, opTypeParam, nil); r != nil {
+					// generic named type
+					return Path(r), nil
+				}
+			}
+			// defined (named) type
+			if r := find(obj, T.Underlying(), append(path, opUnderlying), nil); r != nil {
+				return Path(r), nil
+			}
+		}
+	}
+
+	// Then inspect everything else:
+	// non-types, and declared methods of defined types.
+	for _, o := range objs {
+		path := append(empty, o.Name()...)
+		if _, ok := o.(*types.TypeName); !ok {
+			if o.Exported() {
+				// exported non-type (const, var, func)
+				if r := find(obj, o.Type(), append(path, opType), nil); r != nil {
+					return Path(r), nil
+				}
+			}
+			continue
+		}
+
+		// Inspect declared methods of defined types.
+		if T, ok := aliases.Unalias(o.Type()).(*types.Named); ok {
+			path = append(path, opType)
+			// The method index here is always with respect
+			// to the underlying go/types data structures,
+			// which ultimately derives from source order
+			// and must be preserved by export data.
+			for i := 0; i < T.NumMethods(); i++ {
+				m := T.Method(i)
+				path2 := appendOpArg(path, opMethod, i)
+				if m == obj {
+					return Path(path2), nil // found declared method
+				}
+				if r := find(obj, m.Type(), append(path2, opType), nil); r != nil {
+					return Path(r), nil
+				}
+			}
+		}
+	}
+
+	return "", fmt.Errorf("can't find path for %v in %s", obj, pkg.Path())
+}
+
+func appendOpArg(path []byte, op byte, arg int) []byte {
+	path = append(path, op)
+	path = strconv.AppendInt(path, int64(arg), 10)
+	return path
+}
+
+// concreteMethod returns the path for meth, which must have a non-nil receiver.
+// The second return value indicates success and may be false if the method is
+// an interface method or if it is an instantiated method.
+//
+// This function is just an optimization that avoids the general scope walking
+// approach. You are expected to fall back to the general approach if this
+// function fails.
+func (enc *Encoder) concreteMethod(meth *types.Func) (Path, bool) {
+	// Concrete methods can only be declared on package-scoped named types. For
+	// that reason we can skip the expensive walk over the package scope: the
+	// path will always be package -> named type -> method. We can trivially get
+	// the type name from the receiver, and only have to look over the type's
+	// methods to find the method index.
+	//
+	// Methods on generic types require special consideration, however. Consider
+	// the following package:
+	//
+	// 	L1: type S[T any] struct{}
+	// 	L2: func (recv S[A]) Foo() { recv.Bar() }
+	// 	L3: func (recv S[B]) Bar() { }
+	// 	L4: type Alias = S[int]
+	// 	L5: func _[T any]() { var s S[int]; s.Foo() }
+	//
+	// The receivers of methods on generic types are instantiations. L2 and L3
+	// instantiate S with the type-parameters A and B, which are scoped to the
+	// respective methods. L4 and L5 each instantiate S with int. Each of these
+	// instantiations has its own method set, full of methods (and thus objects)
+	// with receivers whose types are the respective instantiations. In other
+	// words, we have
+	//
+	// S[A].Foo, S[A].Bar
+	// S[B].Foo, S[B].Bar
+	// S[int].Foo, S[int].Bar
+	//
+	// We may thus be trying to produce object paths for any of these objects.
+	//
+	// S[A].Foo and S[B].Bar are the origin methods, and their paths are S.Foo
+	// and S.Bar, which are the paths that this function naturally produces.
+	//
+	// S[A].Bar, S[B].Foo, and both methods on S[int] are instantiations that
+	// don't correspond to the origin methods. For S[int], this is significant.
+	// The most precise object path for S[int].Foo, for example, is Alias.Foo,
+	// not S.Foo. Our function, however, would produce S.Foo, which would
+	// resolve to a different object.
+	//
+	// For S[A].Bar and S[B].Foo it could be argued that S.Bar and S.Foo are
+	// still the correct paths, since only the origin methods have meaningful
+	// paths. But this is likely only true for trivial cases and has edge cases.
+	// Since this function is only an optimization, we err on the side of giving
+	// up, deferring to the slower but definitely correct algorithm. Most users
+	// of objectpath will only be giving us origin methods, anyway, as referring
+	// to instantiated methods is usually not useful.
+
+	if meth.Origin() != meth {
+		return "", false
+	}
+
+	_, named := typesinternal.ReceiverNamed(meth.Type().(*types.Signature).Recv())
+	if named == nil {
+		return "", false
+	}
+
+	if types.IsInterface(named) {
+		// Named interfaces don't have to be package-scoped
+		//
+		// TODO(dominikh): opt: if scope.Lookup(name) == named, then we can apply this optimization to interface
+		// methods, too, I think.
+		return "", false
+	}
+
+	// Preallocate space for the name, opType, opMethod, and some digits.
+	name := named.Obj().Name()
+	path := make([]byte, 0, len(name)+8)
+	path = append(path, name...)
+	path = append(path, opType)
+
+	// Method indices are w.r.t. the go/types data structures,
+	// ultimately deriving from source order,
+	// which is preserved by export data.
+	for i := 0; i < named.NumMethods(); i++ {
+		if named.Method(i) == meth {
+			path = appendOpArg(path, opMethod, i)
+			return Path(path), true
+		}
+	}
+
+	// Due to golang/go#59944, go/types fails to associate the receiver with
+	// certain methods on cgo types.
+	//
+	// TODO(rfindley): replace this panic once golang/go#59944 is fixed in all Go
+	// versions gopls supports.
+	return "", false
+	// panic(fmt.Sprintf("couldn't find method %s on type %s; methods: %#v", meth, named, enc.namedMethods(named)))
+}
+
+// find finds obj within type T, returning the path to it, or nil if not found.
+//
+// The seen map is used to short circuit cycles through type parameters. If
+// nil, it will be allocated as necessary.
+func find(obj types.Object, T types.Type, path []byte, seen map[*types.TypeName]bool) []byte {
+	switch T := T.(type) {
+	case *aliases.Alias:
+		return find(obj, aliases.Unalias(T), path, seen)
+	case *types.Basic, *types.Named:
+		// Named types belonging to pkg were handled already,
+		// so T must belong to another package. No path.
+		return nil
+	case *types.Pointer:
+		return find(obj, T.Elem(), append(path, opElem), seen)
+	case *types.Slice:
+		return find(obj, T.Elem(), append(path, opElem), seen)
+	case *types.Array:
+		return find(obj, T.Elem(), append(path, opElem), seen)
+	case *types.Chan:
+		return find(obj, T.Elem(), append(path, opElem), seen)
+	case *types.Map:
+		if r := find(obj, T.Key(), append(path, opKey), seen); r != nil {
+			return r
+		}
+		return find(obj, T.Elem(), append(path, opElem), seen)
+	case *types.Signature:
+		if r := findTypeParam(obj, T.RecvTypeParams(), path, opRecvTypeParam, nil); r != nil {
+			return r
+		}
+		if r := findTypeParam(obj, T.TypeParams(), path, opTypeParam, seen); r != nil {
+			return r
+		}
+		if r := find(obj, T.Params(), append(path, opParams), seen); r != nil {
+			return r
+		}
+		return find(obj, T.Results(), append(path, opResults), seen)
+	case *types.Struct:
+		for i := 0; i < T.NumFields(); i++ {
+			fld := T.Field(i)
+			path2 := appendOpArg(path, opField, i)
+			if fld == obj {
+				return path2 // found field var
+			}
+			if r := find(obj, fld.Type(), append(path2, opType), seen); r != nil {
+				return r
+			}
+		}
+		return nil
+	case *types.Tuple:
+		for i := 0; i < T.Len(); i++ {
+			v := T.At(i)
+			path2 := appendOpArg(path, opAt, i)
+			if v == obj {
+				return path2 // found param/result var
+			}
+			if r := find(obj, v.Type(), append(path2, opType), seen); r != nil {
+				return r
+			}
+		}
+		return nil
+	case *types.Interface:
+		for i := 0; i < T.NumMethods(); i++ {
+			m := T.Method(i)
+			path2 := appendOpArg(path, opMethod, i)
+			if m == obj {
+				return path2 // found interface method
+			}
+			if r := find(obj, m.Type(), append(path2, opType), seen); r != nil {
+				return r
+			}
+		}
+		return nil
+	case *types.TypeParam:
+		name := T.Obj()
+		if name == obj {
+			return append(path, opObj)
+		}
+		if seen[name] {
+			return nil
+		}
+		if seen == nil {
+			seen = make(map[*types.TypeName]bool)
+		}
+		seen[name] = true
+		if r := find(obj, T.Constraint(), append(path, opConstraint), seen); r != nil {
+			return r
+		}
+		return nil
+	}
+	panic(T)
+}
+
+func findTypeParam(obj types.Object, list *types.TypeParamList, path []byte, op byte, seen map[*types.TypeName]bool) []byte {
+	for i := 0; i < list.Len(); i++ {
+		tparam := list.At(i)
+		path2 := appendOpArg(path, op, i)
+		if r := find(obj, tparam, path2, seen); r != nil {
+			return r
+		}
+	}
+	return nil
+}
+
+// Object returns the object denoted by path p within the package pkg.
+func Object(pkg *types.Package, p Path) (types.Object, error) {
+	pathstr := string(p)
+	if pathstr == "" {
+		return nil, fmt.Errorf("empty path")
+	}
+
+	var pkgobj, suffix string
+	if dot := strings.IndexByte(pathstr, opType); dot < 0 {
+		pkgobj = pathstr
+	} else {
+		pkgobj = pathstr[:dot]
+		suffix = pathstr[dot:] // suffix starts with "."
+	}
+
+	obj := pkg.Scope().Lookup(pkgobj)
+	if obj == nil {
+		return nil, fmt.Errorf("package %s does not contain %q", pkg.Path(), pkgobj)
+	}
+
+	// abstraction of *types.{Pointer,Slice,Array,Chan,Map}
+	type hasElem interface {
+		Elem() types.Type
+	}
+	// abstraction of *types.{Named,Signature}
+	type hasTypeParams interface {
+		TypeParams() *types.TypeParamList
+	}
+	// abstraction of *types.{Named,TypeParam}
+	type hasObj interface {
+		Obj() *types.TypeName
+	}
+
+	// The loop state is the pair (t, obj),
+	// exactly one of which is non-nil, initially obj.
+	// All suffixes start with '.' (the only object->type operation),
+	// followed by optional type->type operations,
+	// then a type->object operation.
+	// The cycle then repeats.
+	var t types.Type
+	for suffix != "" {
+		code := suffix[0]
+		suffix = suffix[1:]
+
+		// Codes [AFMTr] have an integer operand.
+		var index int
+		switch code {
+		case opAt, opField, opMethod, opTypeParam, opRecvTypeParam:
+			rest := strings.TrimLeft(suffix, "0123456789")
+			numerals := suffix[:len(suffix)-len(rest)]
+			suffix = rest
+			i, err := strconv.Atoi(numerals)
+			if err != nil {
+				return nil, fmt.Errorf("invalid path: bad numeric operand %q for code %q", numerals, code)
+			}
+			index = int(i)
+		case opObj:
+			// no operand
+		default:
+			// The suffix must end with a type->object operation.
+			if suffix == "" {
+				return nil, fmt.Errorf("invalid path: ends with %q, want [AFMO]", code)
+			}
+		}
+
+		if code == opType {
+			if t != nil {
+				return nil, fmt.Errorf("invalid path: unexpected %q in type context", opType)
+			}
+			t = obj.Type()
+			obj = nil
+			continue
+		}
+
+		if t == nil {
+			return nil, fmt.Errorf("invalid path: code %q in object context", code)
+		}
+
+		// Inv: t != nil, obj == nil
+
+		t = aliases.Unalias(t)
+		switch code {
+		case opElem:
+			hasElem, ok := t.(hasElem) // Pointer, Slice, Array, Chan, Map
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want pointer, slice, array, chan or map)", code, t, t)
+			}
+			t = hasElem.Elem()
+
+		case opKey:
+			mapType, ok := t.(*types.Map)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want map)", code, t, t)
+			}
+			t = mapType.Key()
+
+		case opParams:
+			sig, ok := t.(*types.Signature)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
+			}
+			t = sig.Params()
+
+		case opResults:
+			sig, ok := t.(*types.Signature)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
+			}
+			t = sig.Results()
+
+		case opUnderlying:
+			named, ok := t.(*types.Named)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want named)", code, t, t)
+			}
+			t = named.Underlying()
+
+		case opTypeParam:
+			hasTypeParams, ok := t.(hasTypeParams) // Named, Signature
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want named or signature)", code, t, t)
+			}
+			tparams := hasTypeParams.TypeParams()
+			if n := tparams.Len(); index >= n {
+				return nil, fmt.Errorf("tuple index %d out of range [0-%d)", index, n)
+			}
+			t = tparams.At(index)
+
+		case opRecvTypeParam:
+			sig, ok := t.(*types.Signature) // Signature
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
+			}
+			rtparams := sig.RecvTypeParams()
+			if n := rtparams.Len(); index >= n {
+				return nil, fmt.Errorf("tuple index %d out of range [0-%d)", index, n)
+			}
+			t = rtparams.At(index)
+
+		case opConstraint:
+			tparam, ok := t.(*types.TypeParam)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want type parameter)", code, t, t)
+			}
+			t = tparam.Constraint()
+
+		case opAt:
+			tuple, ok := t.(*types.Tuple)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want tuple)", code, t, t)
+			}
+			if n := tuple.Len(); index >= n {
+				return nil, fmt.Errorf("tuple index %d out of range [0-%d)", index, n)
+			}
+			obj = tuple.At(index)
+			t = nil
+
+		case opField:
+			structType, ok := t.(*types.Struct)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want struct)", code, t, t)
+			}
+			if n := structType.NumFields(); index >= n {
+				return nil, fmt.Errorf("field index %d out of range [0-%d)", index, n)
+			}
+			obj = structType.Field(index)
+			t = nil
+
+		case opMethod:
+			switch t := t.(type) {
+			case *types.Interface:
+				if index >= t.NumMethods() {
+					return nil, fmt.Errorf("method index %d out of range [0-%d)", index, t.NumMethods())
+				}
+				obj = t.Method(index) // Id-ordered
+
+			case *types.Named:
+				if index >= t.NumMethods() {
+					return nil, fmt.Errorf("method index %d out of range [0-%d)", index, t.NumMethods())
+				}
+				obj = t.Method(index)
+
+			default:
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want interface or named)", code, t, t)
+			}
+			t = nil
+
+		case opObj:
+			hasObj, ok := t.(hasObj)
+			if !ok {
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want named or type param)", code, t, t)
+			}
+			obj = hasObj.Obj()
+			t = nil
+
+		default:
+			return nil, fmt.Errorf("invalid path: unknown code %q", code)
+		}
+	}
+
+	if obj == nil {
+		panic(p) // path does not end in an object-valued operator
+	}
+
+	if obj.Pkg() != pkg {
+		return nil, fmt.Errorf("path denotes %s, which belongs to a different package", obj)
+	}
+
+	return obj, nil // success
+}
+
+// scopeObjects is a memoization of scope objects.
+// Callers must not modify the result.
+func (enc *Encoder) scopeObjects(scope *types.Scope) []types.Object {
+	m := enc.scopeMemo
+	if m == nil {
+		m = make(map[*types.Scope][]types.Object)
+		enc.scopeMemo = m
+	}
+	objs, ok := m[scope]
+	if !ok {
+		names := scope.Names() // allocates and sorts
+		objs = make([]types.Object, len(names))
+		for i, name := range names {
+			objs[i] = scope.Lookup(name)
+		}
+		m[scope] = objs
+	}
+	return objs
+}