From 280c8b90e2785a7de2216cb129752bbeca09210a Mon Sep 17 00:00:00 2001
From: Daniel Morsing <daniel.morsing@gmail.com>
Date: Thu, 29 Aug 2013 16:48:44 +0200
Subject: [PATCH] cmd/gc: make method names for function scoped types unique

Types in function scope can have methods on them if they embed another type, but we didn't make the name unique, meaning that 2 identically named types in different functions would conflict with eachother.

Fixes #6269.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13326045
---
 src/cmd/gc/fmt.c            |  5 ++++-
 test/fixedbugs/issue6269.go | 39 +++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 test/fixedbugs/issue6269.go

diff --git a/src/cmd/gc/fmt.c b/src/cmd/gc/fmt.c
index 8673b39ce6..0db7ed22d2 100644
--- a/src/cmd/gc/fmt.c
+++ b/src/cmd/gc/fmt.c
@@ -604,8 +604,11 @@ typefmt(Fmt *fp, Type *t)
 	if(!(fp->flags&FmtLong) && t->sym && t->etype != TFIELD && t != types[t->etype]) {
 		switch(fmtmode) {
 		case FTypeId:
-			if(fp->flags&FmtShort)
+			if(fp->flags&FmtShort) {
+				if(t->vargen)
+					return fmtprint(fp, "%hS·%d", t->sym, t->vargen);
 				return fmtprint(fp, "%hS", t->sym);
+			}
 			if(fp->flags&FmtUnsigned)
 				return fmtprint(fp, "%uS", t->sym);
 			// fallthrough
diff --git a/test/fixedbugs/issue6269.go b/test/fixedbugs/issue6269.go
new file mode 100644
index 0000000000..af5feb7286
--- /dev/null
+++ b/test/fixedbugs/issue6269.go
@@ -0,0 +1,39 @@
+// run
+
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// issue 6269: name collision on method names for function local types.
+
+package main
+
+type foo struct{}
+
+func (foo) Error() string {
+	return "ok"
+}
+
+type bar struct{}
+
+func (bar) Error() string {
+	return "fail"
+}
+
+func unused() {
+	type collision struct {
+		bar
+	}
+	_ = collision{}
+}
+
+func main() {
+	type collision struct {
+		foo
+	}
+	s := error(collision{})
+	if str := s.Error(); str != "ok" {
+		println("s.Error() ==", str)
+		panic(`s.Error() != "ok"`)
+	}
+}
-- 
2.50.0