From: Agniva De Sarker <agnivade@yahoo.co.in>
Date: Sun, 16 Dec 2018 13:43:25 +0000 (+0530)
Subject: go/doc: handle Examples with no body
X-Git-Tag: go1.12beta1~37
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=e167587dd62a7e1d8683982e2b6eaa1c1cff9c67;p=gostls13.git

go/doc: handle Examples with no body

Fixes #29271

Change-Id: Iff6a16c659ad6ec1b4d9559fcbcd40196086c60e
Reviewed-on: https://go-review.googlesource.com/c/154380
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
---

diff --git a/src/go/doc/example.go b/src/go/doc/example.go
index 45350f8fd3..81956f2fdb 100644
--- a/src/go/doc/example.go
+++ b/src/go/doc/example.go
@@ -426,6 +426,9 @@ func stripOutputComment(body *ast.BlockStmt, comments []*ast.CommentGroup) (*ast
 
 // lastComment returns the last comment inside the provided block.
 func lastComment(b *ast.BlockStmt, c []*ast.CommentGroup) (i int, last *ast.CommentGroup) {
+	if b == nil {
+		return
+	}
 	pos, end := b.Pos(), b.End()
 	for j, cg := range c {
 		if cg.Pos() < pos {
diff --git a/src/go/doc/example_test.go b/src/go/doc/example_test.go
index 0d2bf72e31..74fd10626d 100644
--- a/src/go/doc/example_test.go
+++ b/src/go/doc/example_test.go
@@ -413,6 +413,41 @@ func TestExampleInspectSignature(t *testing.T) {
 	}
 }
 
+const exampleEmpty = `
+package p
+func Example() {}
+func Example_a()
+`
+
+const exampleEmptyOutput = `package main
+
+func main() {}
+func main()
+`
+
+func TestExampleEmpty(t *testing.T) {
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, "test.go", strings.NewReader(exampleEmpty), parser.ParseComments)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	es := doc.Examples(file)
+	if len(es) != 1 {
+		t.Fatalf("wrong number of examples; got %d want 1", len(es))
+	}
+	e := es[0]
+	if e.Name != "" {
+		t.Errorf("got Name == %q, want %q", e.Name, "")
+	}
+	if g, w := formatFile(t, fset, e.Play), exampleEmptyOutput; g != w {
+		t.Errorf("got Play == %q, want %q", g, w)
+	}
+	if g, w := e.Output, ""; g != w {
+		t.Errorf("got Output == %q, want %q", g, w)
+	}
+}
+
 func formatFile(t *testing.T, fset *token.FileSet, n *ast.File) string {
 	if n == nil {
 		return "<nil>"