zipPath, err := modfetch.DownloadZip(ctx, test.m)
			if err != nil {
				if *updateTestData {
					t.Logf("%s: could not download module: %s (will remove from testdata)", test.m, err)
					test.m.Path = "" // mark for deletion
					needUpdate = true
				} else {
					t.Errorf("%s: could not download module: %s", test.m, err)
				}
				return
			}

			sum := modfetch.Sum(ctx, test.m)
			if sum != test.wantSum {

		applyRewrite(f, rewriteBlockdec64, rewriteValuedec64, leaveDeadValues)
	}

	// Split up named values into their components.
	// accumulate old names for aggregates (that are decomposed) in toDelete for efficient bulk deletion,
	// accumulate new LocalSlots in newNames for addition after the iteration.  This decomposition is for
	// builtin types with leaf components, and thus there is no need to reprocess the newly create LocalSlots.

// occurs, it will report the error.
func removeFile(f string) {
	err := os.Remove(f)
	if err == nil || os.IsNotExist(err) {
		return
	}
	// Windows does not allow deletion of a binary file while it is executing.
	if runtime.GOOS == "windows" {
		// Remove lingering ~ file from last attempt.
		if _, err2 := os.Stat(f + "~"); err2 == nil {
			os.Remove(f + "~")
		}

		// Because they don't exist, they will be skipped by Walk.
		for absDir := range haveDirs {
			if str.HasFilePathPrefix(absDir, absArg) {
				if _, ok := keepDirs[absDir]; !ok {
					keepDirs[absDir] = "" // Mark for deletion.
				}
			}
		}
	}

	// Update the work file.
	for absDir, keepDir := range keepDirs {
		nKept := 0
		for _, dir := range haveDirs[absDir] {

			os.Remove(dst + "~")
		}
	}

	mayberemovefile(dst)
	df, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
	if err != nil && runtime.GOOS == "windows" {
		// Windows does not allow deletion of a binary file
		// while it is executing. Try to move it out of the way.
		// If the move fails, which is likely, we'll try again the
		// next time we do an install of this binary.

		//	----------  0 0      0           0 May 13  2014 file4
		//
		// GNU tar v1.27.1 applies global headers to subsequent records,
		// but does not do the following properly:
		//	* It does not treat an empty record as deletion.
		//	* It does not use subsequent global headers to update previous ones.
		//
		//	$ gnutar -tvf pax-global-records.tar
		//	---------- 0/0               0 2017-07-13 19:40 global1

// It should have entries for both module content sums and go.mod sums
// (version ends with "/go.mod"). Existing sums will be preserved unless they
// have been marked for deletion with TrimGoSum.
func WriteGoSum(ctx context.Context, keep map[module.Version]bool, readonly bool) error {
	goSum.mu.Lock()
	defer goSum.mu.Unlock()

	// If we haven't read the go.sum file yet, don't bother writing it.

func (s *Selection) Recv() Type { return s.recv }

// Obj returns the object denoted by x.f; a *Var for
// a field selection, and a *Func in all other cases.
func (s *Selection) Obj() Object { return s.obj }

// Type returns the type of x.f, which may be different from the type of f.
// See Selection for more information.
func (s *Selection) Type() Type {
	switch s.kind {
	case MethodVal:
		// The type of x.f is a method with its receiver type set

func UpdateWorkFile(wf *modfile.WorkFile) {
	missingModulePaths := map[string]string{} // module directory listed in file -> abspath modroot

	for _, d := range wf.Use {
		if d.Path == "" {
			continue // d is marked for deletion.
		}
		modRoot := d.Path
		if d.ModulePath == "" {
			missingModulePaths[d.Path] = modRoot
		}
	}

	// Clean up and annotate directories.
	// TODO(matloob): update x/mod to actually add module paths.

// Most internal data structures are pre-allocated and flat, so for instance adding a
// new relation does not cause any allocation. For performance reasons,
// each node has only up to two outgoing edges (like a binary tree), so intermediate
// "extra" nodes are required to represent more than two relations. For instance,
// to record that A<I, A<J, A<K (with no known relation between I,J,K), we create the
// following DAG:
//
//	  A
//	 / \