From 21b2e168424ee28bd20f7886ab53f68513857fa2 Mon Sep 17 00:00:00 2001
From: Jan Ziak <0xe2.0x9a.0x9b@gmail.com>
Date: Thu, 27 Mar 2014 18:47:00 +0100
Subject: [PATCH] cmd/gc: fix spurious 'use of untyped nil' error

Fixes #6402

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/81340044
---
 src/cmd/gc/const.c          |  5 ++++-
 test/fixedbugs/issue6402.go | 13 +++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 test/fixedbugs/issue6402.go

diff --git a/src/cmd/gc/const.c b/src/cmd/gc/const.c
index cfb1f0adef..a725ea971c 100644
--- a/src/cmd/gc/const.c
+++ b/src/cmd/gc/const.c
@@ -1144,7 +1144,10 @@ defaultlit(Node **np, Type *t)
 		}
 		if(n->val.ctype == CTNIL) {
 			lineno = lno;
-			yyerror("use of untyped nil");
+			if(!n->diag) {
+				yyerror("use of untyped nil");
+				n->diag = 1;
+			}
 			n->type = T;
 			break;
 		}
diff --git a/test/fixedbugs/issue6402.go b/test/fixedbugs/issue6402.go
new file mode 100644
index 0000000000..da5980c9ab
--- /dev/null
+++ b/test/fixedbugs/issue6402.go
@@ -0,0 +1,13 @@
+// errorcheck
+
+// Copyright 2014 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 6402: spurious 'use of untyped nil' error
+
+package p
+
+func f() uintptr {
+	return nil // ERROR "cannot use nil as type uintptr in return argument"
+}
-- 
2.50.0