gopls/internal/golang: fix gopls hover doc link

The hoverJSON.LinkPath field was incorrectly documented, and
the gopls links formed from it were invalid when a module
version was present. This CL fixes the URL logic.

The existing test covered the behavior, but the assertion
concealed a mistake.

Fixes golang/go#70453

Change-Id: If9a7d3e65dabff50c9f528d82df9de67a71c41d1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/630077
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>

Author: adonovan

gopls/internal/golang/hover.go

@@ -72,9 +72,12 @@ type hoverJSON struct {
 	// SymbolName is the human-readable name to use for the symbol in links.
 	SymbolName string `json:"symbolName"`
 
-	// LinkPath is the pkg.go.dev link for the given symbol.
-	// For example, the "go/ast" part of "pkg.go.dev/go/ast#Node".
-	// It may have a module version suffix "@v1.2.3".
+	// LinkPath is the path of the package enclosing the given symbol,
+	// with the module portion (if any) replaced by "module@version".
+	//
+	// For example: "github.com/google/go-github/v48@v48.1.0/github".
+	//
+	// Use LinkTarget + "/" + LinkPath + "#" + LinkAnchor to form a pkgsite URL.
 	LinkPath string `json:"linkPath"`
 
 	// LinkAnchor is the pkg.go.dev link anchor for the given symbol.
@@ -1367,7 +1370,16 @@ func formatLink(h *hoverJSON, options *settings.Options, pkgURL func(path Packag
 	var url protocol.URI
 	var caption string
 	if pkgURL != nil { // LinksInHover == "gopls"
-		path, _, _ := strings.Cut(h.LinkPath, "@") // remove optional module version suffix
+		// Discard optional module version portion.
+		// (Ideally the hoverJSON would retain the structure...)
+		path := h.LinkPath
+		if module, versionDir, ok := strings.Cut(h.LinkPath, "@"); ok {
+			// "module@version/dir"
+			path = module
+			if _, dir, ok := strings.Cut(versionDir, "/"); ok {
+				path += "/" + dir
+			}
+		}
 		url = pkgURL(PackagePath(path), h.LinkAnchor)
 		caption = "in gopls doc viewer"
 	} else {

gopls/internal/test/integration/misc/hover_test.go

@@ -592,7 +592,7 @@ func main() {
 	).Run(t, mod, func(t *testing.T, env *Env) {
 		env.OpenFile("main.go")
 		got, _ := env.Hover(env.RegexpSearch("main.go", "F"))
-		const wantRE = "\\[`a.F` in gopls doc viewer\\]\\(http://127.0.0.1:[0-9]+/gopls/[^/]+/pkg/example.com\\?view=[0-9]+#F\\)" // no version
+		const wantRE = "\\[`a.F` in gopls doc viewer\\]\\(http://127.0.0.1:[0-9]+/gopls/[^/]+/pkg/example.com/a\\?view=[0-9]+#F\\)" // no version
 		if m, err := regexp.MatchString(wantRE, got.Value); err != nil {
 			t.Fatalf("bad regexp in test: %v", err)
 		} else if !m {