gopls/hover: remove header tags from hover markdown

Lines in go doc that look like '// ## Header' generate, by
default, tags in the markdown that look like '{hdr-Header}'
which are harmless and annoying. This CL generates the markdown
without the tags.

Fixes: golang/go#57048
Change-Id: I7109775ea3ec6b51504d62108187e3614b2d1e9d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/456535
Run-TryBot: Peter Weinberger <pjw@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

gopls/internal/lsp/source/comment_go118.go

@@ -32,6 +32,11 @@ func CommentToMarkdown(text string) string {
 	var p comment.Parser
 	doc := p.Parse(text)
 	var pr comment.Printer
+	// The default produces {#Hdr-...} tags for headings.
+	// vscode displays thems, which is undesirable.
+	// The godoc for comment.Printer says the tags
+	// avoid a security problem.
+	pr.HeadingID = func(*comment.Heading) string { return "" }
 	easy := pr.Markdown(doc)
 	return string(easy)
 }

gopls/internal/regtest/misc/hover_test.go

@@ -221,3 +221,42 @@ func main() {
 		}
 	})
 }
+
+// for x/tools/gopls: unhandled named anchor on the hover #57048
+func TestHoverTags(t *testing.T) {
+	testenv.NeedsGo1Point(t, 14) // until go1.13 is dropped from kokoro
+	const source = `
+-- go.mod --
+module mod.com
+
+go 1.19
+
+-- lib/a.go --
+
+// variety of execution modes.
+//
+// # Test package setup
+//
+// The regression test package uses a couple of uncommon patterns to reduce
+package lib
+
+-- a.go --
+	package main
+	import "mod.com/lib"
+
+	const A = 1
+
+}
+`
+	Run(t, source, func(t *testing.T, env *Env) {
+		t.Run("tags", func(t *testing.T) {
+			env.OpenFile("a.go")
+			z := env.RegexpSearch("a.go", "lib")
+			t.Logf("%#v", z)
+			got, _ := env.Hover("a.go", env.RegexpSearch("a.go", "lib"))
+			if strings.Contains(got.Value, "{#hdr-") {
+				t.Errorf("Hover: got {#hdr- tag:\n%q", got)
+			}
+		})
+	})
+}