update to golang.org/x/{crypto,net,text,sync,tools}@latest

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

@@ -1,53 +0,0 @@
-// 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"
-	"strings"
-
-	"golang.org/x/tools/internal/gocommand"
-)
-
-func GetSizesForArgsGolist(ctx context.Context, inv gocommand.Invocation, gocmdRunner *gocommand.Runner) (string, string, 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 {
-		rawErrMsg := rawErr.Error()
-		if 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 "", "", enverr
-			}
-			goarch = strings.TrimSpace(envout.String())
-			compiler = "gc"
-		} else if friendlyErr != nil {
-			return "", "", friendlyErr
-		} else {
-			// This should be unreachable, but be defensive
-			// in case RunRaw's error results are inconsistent.
-			return "", "", rawErr
-		}
-	} else {
-		fields := strings.Fields(stdout.String())
-		if len(fields) < 2 {
-			return "", "", 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 compiler, goarch, nil
-}

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

@@ -198,14 +198,6 @@ 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?

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

@@ -34,8 +34,8 @@ type DriverRequest struct {
 	// 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 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"`
 }
 
@@ -119,7 +119,19 @@ func findExternalDriver(cfg *Config) driver {
 		stderr := new(bytes.Buffer)
 		cmd := exec.CommandContext(cfg.Context, tool, words...)
 		cmd.Dir = cfg.Dir
-		cmd.Env = cfg.Env
+		// 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
@@ -138,3 +150,7 @@ func findExternalDriver(cfg *Config) driver {
 		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.go

@@ -21,7 +21,6 @@ import (
 	"sync"
 	"unicode"
 
-	"golang.org/x/tools/go/internal/packagesdriver"
 	"golang.org/x/tools/internal/gocommand"
 	"golang.org/x/tools/internal/packagesinternal"
 )
@@ -149,7 +148,7 @@ func goListDriver(cfg *Config, patterns ...string) (_ *DriverResponse, err error
 	if cfg.Mode&NeedTypesSizes != 0 || cfg.Mode&NeedTypes != 0 {
 		errCh := make(chan error)
 		go func() {
-			compiler, arch, err := packagesdriver.GetSizesForArgsGolist(ctx, state.cfgInvocation(), cfg.gocmdRunner)
+			compiler, arch, err := getSizesForArgs(ctx, state.cfgInvocation(), cfg.gocmdRunner)
 			response.dr.Compiler = compiler
 			response.dr.Arch = arch
 			errCh <- err
@@ -841,6 +840,7 @@ func (state *golistState) cfgInvocation() gocommand.Invocation {
 		Env:        cfg.Env,
 		Logf:       cfg.Logf,
 		WorkingDir: cfg.Dir,
+		Overlay:    cfg.goListOverlayFile,
 	}
 }
 
@@ -849,26 +849,6 @@ func (state *golistState) invokeGo(verb string, args ...string) (*bytes.Buffer,
 	cfg := state.cfg
 
 	inv := state.cfgInvocation()
-
-	// For Go versions 1.16 and above, `go list` accepts overlays directly via
-	// the -overlay flag. Set it, if it's available.
-	//
-	// The check for "list" is not necessarily required, but we should avoid
-	// getting the go version if possible.
-	if verb == "list" {
-		goVersion, err := state.getGoVersion()
-		if err != nil {
-			return nil, err
-		}
-		if goVersion >= 16 {
-			filename, cleanup, err := state.writeOverlays()
-			if err != nil {
-				return nil, err
-			}
-			defer cleanup()
-			inv.Overlay = filename
-		}
-	}
 	inv.Verb = verb
 	inv.Args = args
 	gocmdRunner := cfg.gocmdRunner
@@ -1015,67 +995,6 @@ func (state *golistState) invokeGo(verb string, args ...string) (*bytes.Buffer,
 	return stdout, nil
 }
 
-// OverlayJSON is the format overlay files are expected to be in.
-// The Replace map maps from overlaid paths to replacement paths:
-// the Go command will forward all reads trying to open
-// each overlaid path to its replacement path, or consider the overlaid
-// path not to exist if the replacement path is empty.
-//
-// From golang/go#39958.
-type OverlayJSON struct {
-	Replace map[string]string `json:"replace,omitempty"`
-}
-
-// writeOverlays writes out files for go list's -overlay flag, as described
-// above.
-func (state *golistState) writeOverlays() (filename string, cleanup func(), err error) {
-	// Do nothing if there are no overlays in the config.
-	if len(state.cfg.Overlay) == 0 {
-		return "", func() {}, nil
-	}
-	dir, err := os.MkdirTemp("", "gopackages-*")
-	if err != nil {
-		return "", nil, err
-	}
-	// The caller must clean up this directory, unless this function returns an
-	// error.
-	cleanup = func() {
-		os.RemoveAll(dir)
-	}
-	defer func() {
-		if err != nil {
-			cleanup()
-		}
-	}()
-	overlays := map[string]string{}
-	for k, v := range state.cfg.Overlay {
-		// Create a unique filename for the overlaid files, to avoid
-		// creating nested directories.
-		noSeparator := strings.Join(strings.Split(filepath.ToSlash(k), "/"), "")
-		f, err := os.CreateTemp(dir, fmt.Sprintf("*-%s", noSeparator))
-		if err != nil {
-			return "", func() {}, err
-		}
-		if _, err := f.Write(v); err != nil {
-			return "", func() {}, err
-		}
-		if err := f.Close(); err != nil {
-			return "", func() {}, err
-		}
-		overlays[k] = f.Name()
-	}
-	b, err := json.Marshal(OverlayJSON{Replace: overlays})
-	if err != nil {
-		return "", func() {}, err
-	}
-	// Write out the overlay file that contains the filepath mappings.
-	filename = filepath.Join(dir, "overlay.json")
-	if err := os.WriteFile(filename, b, 0665); err != nil {
-		return "", func() {}, err
-	}
-	return filename, cleanup, nil
-}
-
 func containsGoFile(s []string) bool {
 	for _, f := range s {
 		if strings.HasSuffix(f, ".go") {
@@ -1104,3 +1023,44 @@ func cmdDebugStr(cmd *exec.Cmd) string {
 	}
 	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, " "))
 }
+
+// getSizesForArgs queries 'go list' for the appropriate
+// Compiler and GOARCH arguments to pass to [types.SizesFor].
+func getSizesForArgs(ctx context.Context, inv gocommand.Invocation, gocmdRunner *gocommand.Runner) (string, string, 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 {
+		rawErrMsg := rawErr.Error()
+		if 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 "", "", enverr
+			}
+			goarch = strings.TrimSpace(envout.String())
+			compiler = "gc"
+		} else if friendlyErr != nil {
+			return "", "", friendlyErr
+		} else {
+			// This should be unreachable, but be defensive
+			// in case RunRaw's error results are inconsistent.
+			return "", "", rawErr
+		}
+	} else {
+		fields := strings.Fields(stdout.String())
+		if len(fields) < 2 {
+			return "", "", 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 compiler, goarch, nil
+}

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

@@ -37,10 +37,19 @@ import (
 // A LoadMode controls the amount of detail to return when loading.
 // The bits below can be combined to specify which fields should be
 // filled in the result packages.
+//
 // The zero value is a special case, equivalent to combining
 // the NeedName, NeedFiles, and NeedCompiledGoFiles bits.
+//
 // ID and Errors (if present) will always be filled.
-// Load may return more information than requested.
+// [Load] may return more information than requested.
+//
+// Unfortunately there are a number of open bugs related to
+// interactions among the LoadMode bits:
+// - https://github.com/golang/go/issues/56633
+// - https://github.com/golang/go/issues/56677
+// - https://github.com/golang/go/issues/58726
+// - https://github.com/golang/go/issues/63517
 type LoadMode int
 
 const (
@@ -66,7 +75,7 @@ const (
 	// NeedTypes adds Types, Fset, and IllTyped.
 	NeedTypes
 
-	// NeedSyntax adds Syntax.
+	// NeedSyntax adds Syntax and Fset.
 	NeedSyntax
 
 	// NeedTypesInfo adds TypesInfo.
@@ -123,15 +132,21 @@ const (
 
 // A Config specifies details about how packages should be loaded.
 // The zero value is a valid configuration.
+//
 // Calls to Load do not modify this struct.
+//
+// TODO(adonovan): #67702: this is currently false: in fact,
+// calls to [Load] do not modify the public fields of this struct, but
+// may modify hidden fields, so concurrent calls to [Load] must not
+// use the same Config. But perhaps we should reestablish the
+// documented invariant.
 type Config struct {
 	// Mode controls the level of information returned for each package.
 	Mode LoadMode
 
 	// Context specifies the context for the load operation.
-	// If the context is cancelled, the loader may stop early
-	// and return an ErrCancelled error.
-	// If Context is nil, the load cannot be cancelled.
+	// Cancelling the context may cause [Load] to abort and
+	// return an error.
 	Context context.Context
 
 	// Logf is the logger for the config.
@@ -200,13 +215,23 @@ type Config struct {
 	// setting Tests may have no effect.
 	Tests bool
 
-	// Overlay provides a mapping of absolute file paths to file contents.
-	// If the file with the given path already exists, the parser will use the
-	// alternative file contents provided by the map.
+	// Overlay is a mapping from absolute file paths to file contents.
 	//
-	// Overlays provide incomplete support for when a given file doesn't
-	// already exist on disk. See the package doc above for more details.
+	// For each map entry, [Load] uses the alternative file
+	// contents provided by the overlay mapping instead of reading
+	// from the file system. This mechanism can be used to enable
+	// editor-integrated tools to correctly analyze the contents
+	// of modified but unsaved buffers, for example.
+	//
+	// The overlay mapping is passed to the build system's driver
+	// (see "The driver protocol") so that it too can report
+	// consistent package metadata about unsaved files. However,
+	// drivers may vary in their level of support for overlays.
 	Overlay map[string][]byte
+
+	// goListOverlayFile is the JSON file that encodes the Overlay
+	// mapping, used by 'go list -overlay=...'
+	goListOverlayFile string
 }
 
 // Load loads and returns the Go packages named by the given patterns.
@@ -214,8 +239,22 @@ type Config struct {
 // Config specifies loading options;
 // nil behaves the same as an empty Config.
 //
-// Load returns an error if any of the patterns was invalid
-// as defined by the underlying build system.
+// The [Config.Mode] field is a set of bits that determine what kinds
+// of information should be computed and returned. Modes that require
+// more information tend to be slower. See [LoadMode] for details
+// and important caveats. Its zero value is equivalent to
+// NeedName | NeedFiles | NeedCompiledGoFiles.
+//
+// Each call to Load returns a new set of [Package] instances.
+// The Packages and their Imports form a directed acyclic graph.
+//
+// If the [NeedTypes] mode flag was set, each call to Load uses a new
+// [types.Importer], so [types.Object] and [types.Type] values from
+// different calls to Load must not be mixed as they will have
+// inconsistent notions of type identity.
+//
+// If any of the patterns was invalid as defined by the
+// underlying build system, Load returns an error.
 // It may return an empty list of packages without an error,
 // for instance for an empty expansion of a valid wildcard.
 // Errors associated with a particular package are recorded in the
@@ -287,6 +326,17 @@ func defaultDriver(cfg *Config, patterns ...string) (*DriverResponse, bool, erro
 		// (fall through)
 	}
 
+	// go list fallback
+	//
+	// Write overlays once, as there are many calls
+	// to 'go list' (one per chunk plus others too).
+	overlay, cleanupOverlay, err := gocommand.WriteOverlays(cfg.Overlay)
+	if err != nil {
+		return nil, false, err
+	}
+	defer cleanupOverlay()
+	cfg.goListOverlayFile = overlay
+
 	response, err := callDriverOnChunks(goListDriver, cfg, chunks)
 	if err != nil {
 		return nil, false, err
@@ -366,6 +416,9 @@ func mergeResponses(responses ...*DriverResponse) *DriverResponse {
 }
 
 // A Package describes a loaded Go package.
+//
+// It also defines part of the JSON schema of [DriverResponse].
+// See the package documentation for an overview.
 type Package struct {
 	// ID is a unique identifier for a package,
 	// in a syntax provided by the underlying build system.
@@ -424,19 +477,30 @@ type Package struct {
 	// to corresponding loaded Packages.
 	Imports map[string]*Package
 
+	// Module is the module information for the package if it exists.
+	//
+	// Note: it may be missing for std and cmd; see Go issue #65816.
+	Module *Module
+
+	// -- The following fields are not part of the driver JSON schema. --
+
 	// Types provides type information for the package.
 	// The NeedTypes LoadMode bit sets this field for packages matching the
 	// patterns; type information for dependencies may be missing or incomplete,
 	// unless NeedDeps and NeedImports are also set.
-	Types *types.Package
+	//
+	// Each call to [Load] returns a consistent set of type
+	// symbols, as defined by the comment at [types.Identical].
+	// Avoid mixing type information from two or more calls to [Load].
+	Types *types.Package `json:"-"`
 
 	// Fset provides position information for Types, TypesInfo, and Syntax.
 	// It is set only when Types is set.
-	Fset *token.FileSet
+	Fset *token.FileSet `json:"-"`
 
 	// IllTyped indicates whether the package or any dependency contains errors.
 	// It is set only when Types is set.
-	IllTyped bool
+	IllTyped bool `json:"-"`
 
 	// Syntax is the package's syntax trees, for the files listed in CompiledGoFiles.
 	//
@@ -446,26 +510,28 @@ type Package struct {
 	//
 	// Syntax is kept in the same order as CompiledGoFiles, with the caveat that nils are
 	// removed.  If parsing returned nil, Syntax may be shorter than CompiledGoFiles.
-	Syntax []*ast.File
+	Syntax []*ast.File `json:"-"`
 
 	// TypesInfo provides type information about the package's syntax trees.
 	// It is set only when Syntax is set.
-	TypesInfo *types.Info
+	TypesInfo *types.Info `json:"-"`
 
 	// TypesSizes provides the effective size function for types in TypesInfo.
-	TypesSizes types.Sizes
+	TypesSizes types.Sizes `json:"-"`
+
+	// -- internal --
 
 	// forTest is the package under test, if any.
 	forTest string
 
 	// depsErrors is the DepsErrors field from the go list response, if any.
 	depsErrors []*packagesinternal.PackageError
-
-	// module is the module information for the package if it exists.
-	Module *Module
 }
 
 // Module provides module information for a package.
+//
+// It also defines part of the JSON schema of [DriverResponse].
+// See the package documentation for an overview.
 type Module struct {
 	Path      string       // module path
 	Version   string       // module version
@@ -598,6 +664,7 @@ func (p *Package) UnmarshalJSON(b []byte) error {
 		OtherFiles:      flat.OtherFiles,
 		EmbedFiles:      flat.EmbedFiles,
 		EmbedPatterns:   flat.EmbedPatterns,
+		IgnoredFiles:    flat.IgnoredFiles,
 		ExportFile:      flat.ExportFile,
 	}
 	if len(flat.Imports) > 0 {
@@ -854,6 +921,12 @@ func (ld *loader) refine(response *DriverResponse) ([]*Package, error) {
 		wg.Wait()
 	}
 
+	// If the context is done, return its error and
+	// throw out [likely] incomplete packages.
+	if err := ld.Context.Err(); err != nil {
+		return nil, err
+	}
+
 	result := make([]*Package, len(initial))
 	for i, lpkg := range initial {
 		result[i] = lpkg.Package
@@ -887,12 +960,14 @@ func (ld *loader) refine(response *DriverResponse) ([]*Package, error) {
 		}
 		if ld.requestedMode&NeedTypes == 0 {
 			ld.pkgs[i].Types = nil
-			ld.pkgs[i].Fset = nil
 			ld.pkgs[i].IllTyped = false
 		}
 		if ld.requestedMode&NeedSyntax == 0 {
 			ld.pkgs[i].Syntax = nil
 		}
+		if ld.requestedMode&NeedTypes == 0 && ld.requestedMode&NeedSyntax == 0 {
+			ld.pkgs[i].Fset = nil
+		}
 		if ld.requestedMode&NeedTypesInfo == 0 {
 			ld.pkgs[i].TypesInfo = nil
 		}
@@ -949,6 +1024,14 @@ func (ld *loader) loadPackage(lpkg *loaderPackage) {
 	lpkg.Types = types.NewPackage(lpkg.PkgPath, lpkg.Name)
 	lpkg.Fset = ld.Fset
 
+	// Start shutting down if the context is done and do not load
+	// source or export data files.
+	// Packages that import this one will have ld.Context.Err() != nil.
+	// ld.Context.Err() will be returned later by refine.
+	if ld.Context.Err() != nil {
+		return
+	}
+
 	// Subtle: we populate all Types fields with an empty Package
 	// before loading export data so that export data processing
 	// never has to create a types.Package for an indirect dependency,
@@ -1068,6 +1151,13 @@ func (ld *loader) loadPackage(lpkg *loaderPackage) {
 		return
 	}
 
+	// Start shutting down if the context is done and do not type check.
+	// Packages that import this one will have ld.Context.Err() != nil.
+	// ld.Context.Err() will be returned later by refine.
+	if ld.Context.Err() != nil {
+		return
+	}
+
 	lpkg.TypesInfo = &types.Info{
 		Types:      make(map[ast.Expr]types.TypeAndValue),
 		Defs:       make(map[*ast.Ident]types.Object),
@@ -1245,11 +1335,6 @@ func (ld *loader) parseFiles(filenames []string) ([]*ast.File, []error) {
 	parsed := make([]*ast.File, n)
 	errors := make([]error, n)
 	for i, file := range filenames {
-		if ld.Config.Context.Err() != nil {
-			parsed[i] = nil
-			errors[i] = ld.Config.Context.Err()
-			continue
-		}
 		wg.Add(1)
 		go func(i int, filename string) {
 			parsed[i], errors[i] = ld.parseFile(filename)
@@ -1415,6 +1500,10 @@ func impliedLoadMode(loadMode LoadMode) LoadMode {
 		// All these things require knowing the import graph.
 		loadMode |= NeedImports
 	}
+	if loadMode&NeedTypes != 0 {
+		// Types require the GoVersion from Module.
+		loadMode |= NeedModule
+	}
 
 	return loadMode
 }

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

@@ -49,11 +49,20 @@ func Visit(pkgs []*Package, pre func(*Package) bool, post func(*Package)) {
 // PrintErrors returns the number of errors printed.
 func PrintErrors(pkgs []*Package) int {
 	var n int
+	errModules := make(map[*Module]bool)
 	Visit(pkgs, nil, func(pkg *Package) {
 		for _, err := range pkg.Errors {
 			fmt.Fprintln(os.Stderr, err)
 			n++
 		}
+
+		// Print pkg.Module.Error once if present.
+		mod := pkg.Module
+		if mod != nil && mod.Error != nil && !errModules[mod] {
+			errModules[mod] = true
+			fmt.Fprintln(os.Stderr, mod.Error.Err)
+			n++
+		}
 	})
 	return n
 }

vendor/golang.org/x/tools/go/types/objectpath/objectpath.go

@@ -51,7 +51,7 @@ type Path string
 //
 //	PO package->object	Package.Scope.Lookup
 //	OT  object->type 	Object.Type
-//	TT    type->type 	Type.{Elem,Key,Params,Results,Underlying} [EKPRU]
+//	TT    type->type 	Type.{Elem,Key,{,{,Recv}Type}Params,Results,Underlying,Rhs} [EKPRUTrCa]
 //	TO   type->object	Type.{At,Field,Method,Obj} [AFMO]
 //
 // All valid paths start with a package and end at an object
@@ -63,8 +63,8 @@ type Path string
 //   - 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 [EKPRUTC];
-//     one of these (TypeParam) requires an integer operand,
+//   - The TT operators are encoded as [EKPRUTrCa];
+//     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,
@@ -98,19 +98,21 @@ const (
 	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)
-	opConstraint = 'C' // .Constraint()     (TypeParam)
+	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)
+	opRhs           = 'a' // .Rhs()			(Alias)
 
 	// 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)
+	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).
@@ -278,21 +280,26 @@ func (enc *Encoder) For(obj types.Object) (Path, error) {
 		path = append(path, opType)
 
 		T := o.Type()
+		if alias, ok := T.(*aliases.Alias); ok {
+			if r := findTypeParam(obj, aliases.TypeParams(alias), path, opTypeParam, nil); r != nil {
+				return Path(r), nil
+			}
+			if r := find(obj, aliases.Rhs(alias), append(path, opRhs), nil); r != nil {
+				return Path(r), nil
+			}
 
-		if tname.IsAlias() {
-			// type alias
+		} else if tname.IsAlias() {
+			// legacy 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, nil); r != nil {
-					// generic named type
-					return Path(r), nil
-				}
-			}
+
+		} else if named, ok := T.(*types.Named); ok {
 			// defined (named) type
-			if r := find(obj, T.Underlying(), append(path, opUnderlying), nil); r != nil {
+			if r := findTypeParam(obj, named.TypeParams(), path, opTypeParam, nil); r != nil {
+				return Path(r), nil
+			}
+			if r := find(obj, named.Underlying(), append(path, opUnderlying), nil); r != nil {
 				return Path(r), nil
 			}
 		}
@@ -462,7 +469,10 @@ func find(obj types.Object, T types.Type, path []byte, seen map[*types.TypeName]
 		}
 		return find(obj, T.Elem(), append(path, opElem), seen)
 	case *types.Signature:
-		if r := findTypeParam(obj, T.TypeParams(), path, seen); r != nil {
+		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 {
@@ -525,10 +535,10 @@ func find(obj types.Object, T types.Type, path []byte, seen map[*types.TypeName]
 	panic(T)
 }
 
-func findTypeParam(obj types.Object, list *types.TypeParamList, path []byte, seen map[*types.TypeName]bool) []byte {
+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, opTypeParam, i)
+		path2 := appendOpArg(path, op, i)
 		if r := find(obj, tparam, path2, seen); r != nil {
 			return r
 		}
@@ -580,10 +590,10 @@ func Object(pkg *types.Package, p Path) (types.Object, error) {
 		code := suffix[0]
 		suffix = suffix[1:]
 
-		// Codes [AFM] have an integer operand.
+		// Codes [AFMTr] have an integer operand.
 		var index int
 		switch code {
-		case opAt, opField, opMethod, opTypeParam:
+		case opAt, opField, opMethod, opTypeParam, opRecvTypeParam:
 			rest := strings.TrimLeft(suffix, "0123456789")
 			numerals := suffix[:len(suffix)-len(rest)]
 			suffix = rest
@@ -653,6 +663,16 @@ func Object(pkg *types.Package, p Path) (types.Object, error) {
 			}
 			t = named.Underlying()
 
+		case opRhs:
+			if alias, ok := t.(*aliases.Alias); ok {
+				t = aliases.Rhs(alias)
+			} else if false && aliases.Enabled() {
+				// The Enabled check is too expensive, so for now we
+				// simply assume that aliases are not enabled.
+				// TODO(adonovan): replace with "if true {" when go1.24 is assured.
+				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want alias)", code, t, t)
+			}
+
 		case opTypeParam:
 			hasTypeParams, ok := t.(hasTypeParams) // Named, Signature
 			if !ok {
@@ -664,6 +684,17 @@ func Object(pkg *types.Package, p Path) (types.Object, error) {
 			}
 			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 {
@@ -725,6 +756,10 @@ func Object(pkg *types.Package, p Path) (types.Object, error) {
 		}
 	}
 
+	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)
 	}