}
	key := typ + ":" + name
	dir = filepath.Join(cfg.GOMODCACHE, "cache/vcs", fmt.Sprintf("%x", sha256.Sum256([]byte(key))))

	xLog, buildX := cfg.BuildXWriter(ctx)
	if buildX {
		fmt.Fprintf(xLog, "mkdir -p %s # %s %s\n", filepath.Dir(dir), typ, name)
	}
	if err := os.MkdirAll(filepath.Dir(dir), 0777); err != nil {
		return "", "", err
	}

	return context.WithValue(ctx, buildXContextKey{}, xLog)
}

type buildXContextKey struct{}

// BuildXWriter returns nil if BuildX is false, or
// the writer to which BuildX output should be written otherwise.
func BuildXWriter(ctx context.Context) (io.Writer, bool) {
	if !BuildX {
		return nil, false
	}
	if v := ctx.Value(buildXContextKey{}); v != nil {