cmd/go/internal/doc: pass URL fragments separately with -http

Plumb URL fragments separately when invoking pkgsite so the `#` doesn't
get %-encoded into the path.

Fixes: golang#75088
Change-Id: I33814fc6a192dff3e4f3d0b9d81205056dddd438
Reviewed-on: https://go-review.googlesource.com/c/go/+/697435
Reviewed-by: Sean Liao <sean@liao.dev>
Reviewed-by: Ian Alexander <jitsu@google.com>
Reviewed-by: Michael Matloob <matloob@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Matloob <matloob@golang.org>

Author: dfinkel

src/cmd/go/internal/doc/doc.go

@@ -212,16 +212,16 @@ func do(writer io.Writer, flagSet *flag.FlagSet, args []string) (err error) {
 			mod, err := runCmd(append(os.Environ(), "GOWORK=off"), "go", "list", "-m")
 			if err == nil && mod != "" && mod != "command-line-arguments" {
 				// If there's a module, go to the module's doc page.
-				return doPkgsite(mod)
+				return doPkgsite(mod, "")
 			}
 			gowork, err := runCmd(nil, "go", "env", "GOWORK")
 			if err == nil && gowork != "" {
 				// Outside a module, but in a workspace, go to the home page
 				// with links to each of the modules' pages.
-				return doPkgsite("")
+				return doPkgsite("", "")
 			}
 			// Outside a module or workspace, go to the documentation for the standard library.
-			return doPkgsite("std")
+			return doPkgsite("std", "")
 		}
 
 		// If args are provided, we need to figure out which page to open on the pkgsite
@@ -282,11 +282,11 @@ func do(writer io.Writer, flagSet *flag.FlagSet, args []string) (err error) {
 		}
 		if found {
 			if serveHTTP {
-				path, err := objectPath(userPath, pkg, symbol, method)
+				path, fragment, err := objectPath(userPath, pkg, symbol, method)
 				if err != nil {
 					return err
 				}
-				return doPkgsite(path)
+				return doPkgsite(path, fragment)
 			}
 			return nil
 		}
@@ -305,7 +305,8 @@ func runCmd(env []string, cmdline ...string) (string, error) {
 	return strings.TrimSpace(stdout.String()), nil
 }
 
-func objectPath(userPath string, pkg *Package, symbol, method string) (string, error) {
+// returns a path followed by a fragment (or an error)
+func objectPath(userPath string, pkg *Package, symbol, method string) (string, string, error) {
 	var err error
 	path := pkg.build.ImportPath
 	if path == "." {
@@ -314,18 +315,15 @@ func objectPath(userPath string, pkg *Package, symbol, method string) (string, e
 		// go list to get the import path.
 		path, err = runCmd(nil, "go", "list", userPath)
 		if err != nil {
-			return "", err
+			return "", "", err
 		}
 	}
 
 	object := symbol
 	if symbol != "" && method != "" {
 		object = symbol + "." + method
 	}
-	if object != "" {
-		path = path + "#" + object
-	}
-	return path, nil
+	return path, object, nil
 }
 
 // failMessage creates a nicely formatted error message when there is no result to show.

src/cmd/go/internal/doc/pkgsite.go

@@ -34,7 +34,7 @@ func pickUnusedPort() (int, error) {
 	return port, nil
 }
 
-func doPkgsite(urlPath string) error {
+func doPkgsite(urlPath, fragment string) error {
 	port, err := pickUnusedPort()
 	if err != nil {
 		return fmt.Errorf("failed to find port for documentation server: %v", err)
@@ -44,6 +44,9 @@ func doPkgsite(urlPath string) error {
 	if err != nil {
 		return fmt.Errorf("internal error: failed to construct url: %v", err)
 	}
+	if fragment != "" {
+		path += "#" + fragment
+	}
 
 	// Turn off the default signal handler for SIGINT (and SIGQUIT on Unix)
 	// and instead wait for the child process to handle the signal and

src/cmd/go/internal/doc/pkgsite_bootstrap.go

@@ -8,4 +8,4 @@
 
 package doc
 
-func doPkgsite(string) error { return nil }
+func doPkgsite(string, string) error { return nil }