// https://pkg.go.dev/cmd/go/#hdr-The_go_mod_file.
//
// The [Parse] and [ParseLax] functions both parse a go.mod file and return an
// abstract syntax tree. ParseLax ignores unknown statements and may be used to
// parse go.mod files that may have been developed with newer versions of Go.
//
// The [File] struct returned by Parse and ParseLax represent an abstract
// go.mod file. File has several methods like [File.AddNewRequire] and

	}
	return rawGoModSummaryCache.Do(m, func() (*modFileSummary, error) {
		summary := new(modFileSummary)
		name, data, err := rawGoModData(m)
		if err != nil {
			return nil, err
		}
		f, err := modfile.ParseLax(name, data, nil)
		if err != nil {
			return nil, module.VersionError(m, fmt.Errorf("parsing %s: %v", base.ShortPath(name), err))
		}
		if f.Module != nil {
			summary.module = f.Module.Mod

			break
		}
	}
	if highest == "" {
		highest = versions[len(versions)-1]
	}

	data, err := r.GoMod(ctx, highest)
	if err != nil {
		return nil, err
	}
	f, err := modfile.ParseLax("go.mod", data, nil)
	if err != nil {
		return nil, err
	}
	retractions := make([]modfile.VersionInterval, 0, len(f.Retract))
	for _, r := range f.Retract {

			}
		}
		if err != nil {
			return ErrHeader
		}
	}
	hdr.PAXRecords = paxHdrs
	return nil
}

// parsePAX parses PAX headers.
// If an extended header (type 'x') is invalid, ErrHeader is returned.
func parsePAX(r io.Reader) (map[string]string, error) {
	buf, err := readSpecialFile(r)
	if err != nil {
		return nil, err
	}
	sbuf := string(buf)

	}

	for i, v := range vectors {
		r := strings.NewReader(v.in)
		got, err := parsePAX(r)
		if !reflect.DeepEqual(got, v.want) && !(len(got) == 0 && len(v.want) == 0) {
			t.Errorf("test %d, parsePAX():\ngot  %v\nwant %v", i, got, v.want)
		}
		if ok := err == nil; ok != v.ok {
			t.Errorf("test %d, parsePAX(): got %v, want %v", i, ok, v.ok)
		}
	}
}

func TestReadOldGNUSparseMap(t *testing.T) {