cmd/go/internal/get: simplify scheme lookup

Fixes #26123

Change-Id: If0dad65a3885d2146624f2aac42099e9eca9670e
Reviewed-on: https://go-review.googlesource.com/c/go/+/200758
Run-TryBot: Bryan C. Mills <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Jay Conrod <[email protected]>

src/cmd/go/internal/get/vcs.go

@@ -531,12 +531,12 @@ func (v *vcsCmd) tagSync(dir, tag string) error {
 // A vcsPath describes how to convert an import path into a
 // version control system and repository name.
 type vcsPath struct {
- prefix string // prefix this description applies to
- regexp *lazyregexp.Regexp // compiled pattern for import path
- repo string // repository to use (expand with match of re)
- vcs string // version control system to use (expand with match of re)
- check func(match map[string]string) error // additional checks
- ping bool // ping for scheme to use to download repo
+ prefix  string // prefix this description applies to
+ regexp  *lazyregexp.Regexp // compiled pattern for import path
+ repo  string // repository to use (expand with match of re)
+ vcs  string // version control system to use (expand with match of re)
+ check  func(match map[string]string) error // additional checks
+ schemelessRepo bool // if true, the repo pattern lacks a scheme
 }
 
 // vcsFromDir inspects dir and its parents to determine the
@@ -657,15 +657,15 @@ const (
 // RepoRootForImportPath analyzes importPath to determine the
 // version control system, and code repository to use.
 func RepoRootForImportPath(importPath string, mod ModuleMode, security web.SecurityMode) (*RepoRoot, error) {
- rr, err := repoRootFromVCSPaths(importPath, "", security, vcsPaths)
+ rr, err := repoRootFromVCSPaths(importPath, security, vcsPaths)
  if err == errUnknownSite {
  rr, err = repoRootForImportDynamic(importPath, mod, security)
  if err != nil {
  err = fmt.Errorf("unrecognized import path %q: %v", importPath, err)
  }
  }
  if err != nil {
- rr1, err1 := repoRootFromVCSPaths(importPath, "", security, vcsPathsAfterDynamic)
+ rr1, err1 := repoRootFromVCSPaths(importPath, security, vcsPathsAfterDynamic)
  if err1 == nil {
  rr = rr1
  err = nil
@@ -685,8 +685,7 @@ var errUnknownSite = errors.New("dynamic lookup required to find mapping")
 
 // repoRootFromVCSPaths attempts to map importPath to a repoRoot
 // using the mappings defined in vcsPaths.
-// If scheme is non-empty, that scheme is forced.
-func repoRootFromVCSPaths(importPath, scheme string, security web.SecurityMode, vcsPaths []*vcsPath) (*RepoRoot, error) {
+func repoRootFromVCSPaths(importPath string, security web.SecurityMode, vcsPaths []*vcsPath) (*RepoRoot, error) {
  // A common error is to use https://packagepath because that's what
  // hg and git require. Diagnose this helpfully.
  if prefix := httpPrefix(importPath); prefix != "" {
@@ -731,26 +730,28 @@ func repoRootFromVCSPaths(importPath, scheme string, security web.SecurityMode,
  if vcs == nil {
  return nil, fmt.Errorf("unknown version control system %q", match["vcs"])
  }
- if srv.ping {
- if scheme != "" {
- match["repo"] = scheme + ":https://" + match["repo"]
- } else {
- for _, scheme := range vcs.scheme {
- if security == web.SecureOnly && !vcs.isSecureScheme(scheme) {
+ var repoURL string
+ if !srv.schemelessRepo {
+ repoURL = match["repo"]
+ } else {
+ scheme := vcs.scheme[0] // default to first scheme
+ repo := match["repo"]
+ if vcs.pingCmd != "" {
+ // If we know how to test schemes, scan to find one.
+ for _, s := range vcs.scheme {
+ if security == web.SecureOnly && !vcs.isSecureScheme(s) {
  continue
  }
- if vcs.pingCmd != "" && vcs.ping(scheme, match["repo"]) == nil {
- match["repo"] = scheme + ":https://" + match["repo"]
- goto Found
+ if vcs.ping(s, repo) == nil {
+ scheme = s
+ break
  }
  }
- // No scheme found. Fall back to the first one.
- match["repo"] = vcs.scheme[0] + ":https://" + match["repo"]
- Found:
  }
+ repoURL = scheme + ":https://" + repo
  }
  rr := &RepoRoot{
- Repo: match["repo"],
+ Repo: repoURL,
  Root: match["root"],
  VCS: vcs.cmd,
  vcs: vcs,
@@ -1075,8 +1076,8 @@ var vcsPaths = []*vcsPath{
  // General syntax for any server.
  // Must be last.
  {
- regexp: lazyregexp.New(`(?P<root>(?P<repo>([a-z0-9.\-]+\.)+[a-z0-9.\-]+(:[0-9]+)?(/~?[A-Za-z0-9_.\-]+)+?)\.(?P<vcs>bzr|fossil|git|hg|svn))(/~?[A-Za-z0-9_.\-]+)*$`),
- ping:  true,
+ regexp:  lazyregexp.New(`(?P<root>(?P<repo>([a-z0-9.\-]+\.)+[a-z0-9.\-]+(:[0-9]+)?(/~?[A-Za-z0-9_.\-]+)+?)\.(?P<vcs>bzr|fossil|git|hg|svn))(/~?[A-Za-z0-9_.\-]+)*$`),
+ schemelessRepo: true,
  },
 }