cmp stdout want

-- want --
{
	"ImportPath": "m/c",
	"DepsErrors": [
		{
			"ImportStack": [
				"m/a",
				"m/b",
				"m/c",
				"m/a"
			],
			"Pos": "",
			"Err": "import cycle not allowed"
		}
	]
}
{
	"ImportPath": "m/b",
	"DepsErrors": [
		{
			"ImportStack": [
				"m/a",
				"m/b",
				"m/c",
				"m/a"
			],
			"Pos": "",

	return e.importPath
}

// An ImportStack is a stack of import paths, possibly with the suffix " (test)" appended.
// The import path of a test package is the import path of the corresponding
// non-test package with the suffix "_test" added.
type ImportStack []string

func (s *ImportStack) Push(p string) {
	*s = append(*s, p)
}

func (s *ImportStack) Pop() {
	*s = (*s)[0 : len(*s)-1]
}

	allImports = append(allImports, p.XTestImports...)
	pre.preloadImports(ctx, opts, allImports, p.Internal.Build)

	var ptestErr, pxtestErr *PackageError
	var imports, ximports []*Package
	var stk ImportStack
	var testEmbed, xtestEmbed map[string][]string
	var incomplete bool
	stk.Push(p.ImportPath + " (test)")
	rawTestImports := str.StringList(p.TestImports)
	for i, path := range p.TestImports {

	// the package the error was produced for. Each package can have at most
	// one error set on it.
	sort.Slice(p.DepsErrors, func(i, j int) bool {
		stki, stkj := p.DepsErrors[i].ImportStack, p.DepsErrors[j].ImportStack
		// Some packages are missing import stacks. To ensure deterministic
		// sort order compare two errors that are missing import stacks by
		// their errors' error texts.
		if len(stki) == 0 {

// an ELF note with name "Go\x00\x00" and type 1. For GCCGO it is extracted from the
// .go_export section.
func readpkglist(shlibpath string) (pkgs []*load.Package) {
	var stk load.ImportStack
	if cfg.BuildToolchainName == "gccgo" {
		f, err := elf.Open(shlibpath)
		if err != nil {
			base.Fatal(fmt.Errorf("failed to open shared library: %v", err))
		}
		defer f.Close()

// expanded import paths. See golang.org/s/go15vendor for more about vendoring.
//
// The error information, if any, is
//
//	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
//	}
//