}
}

// PathMajorPrefix returns the major-version tag prefix implied by pathMajor.
// An empty PathMajorPrefix allows either v0 or v1.
//
// Note that [MatchPathMajor] may accept some versions that do not actually begin
// with this prefix: namely, it accepts a 'v0.0.0-' prefix for a '.v1'
// pathMajor, even though that pathMajor implies 'v1' tagging.
func PathMajorPrefix(pathMajor string) string {

	}
	pathPrefix, pathMajor, ok := module.SplitPathVersion(path)
	if !ok {
		return nil, fmt.Errorf("invalid module path %q", path)
	}
	if codeRoot == path {
		pathPrefix = path
	}
	pseudoMajor := module.PathMajorPrefix(pathMajor)

	// Compute codeDir = bar, the subdirectory within the repo
	// corresponding to the module root.
	//
	// At this point we might have:
	//	path = github.com/rsc/foo/bar/v2

				Version: vers,
				Err:     fmt.Errorf("must be of the form v1.2.3"),
			}
		}
		return &module.InvalidVersionError{
			Version: vers,
			Err:     fmt.Errorf("must be of the form %s.2.3", module.PathMajorPrefix(pathMajor)),
		}
	}

	if pathMajorOk {
		if err := module.CheckPathMajor(vers, pathMajor); err != nil {
			if pathMajor == "" {