go/parser: handle last line comments

Fixes #20636

Change-Id: Icea0012fecb73944c95f6037922505c63b57b245
Reviewed-on: https://go-review.googlesource.com/45295
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/go/parser/parser_test.go b/src/go/parser/parser_test.go
index c7bb36d789..fb35a88ba1 100644
--- a/src/go/parser/parser_test.go
+++ b/src/go/parser/parser_test.go
@@ -531,3 +531,18 @@ func TestIncompleteSelection(t *testing.T) {
 		}
 	}
 }
+
+func TestLastLineComment(t *testing.T) {
+	const src = `package main
+type x int // comment
+`
+	fset := token.NewFileSet()
+	f, err := ParseFile(fset, "", src, ParseComments)
+	if err != nil {
+		t.Fatal(err)
+	}
+	comment := f.Decls[0].(*ast.GenDecl).Specs[0].(*ast.TypeSpec).Comment.List[0].Text
+	if comment != "// comment" {
+		t.Errorf("got %q, want %q", comment, "// comment")
+	}
+}