From: Russ Cox <rsc@golang.org>
Date: Tue, 15 May 2012 16:51:58 +0000 (-0400)
Subject: cmd/gc: make append(nil, x) error more precise
X-Git-Tag: go1.1rc2~3204
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=fcc1f2ac557602f4097e498fa4dd879fb5a680a5;p=gostls13.git

cmd/gc: make append(nil, x) error more precise

Before:
./x.go:6: first argument to append must be slice; have nil

After:
./x.go:6: first argument to append must be typed slice; have untyped nil

Fixes #3616.

R=ken2
CC=golang-dev
https://golang.org/cl/6209067
---

diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index e98d538572..02d6cc4777 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -1140,6 +1140,10 @@ reswitch:
 			goto error;
 		n->type = t;
 		if(!isslice(t)) {
+			if(isconst(args->n, CTNIL)) {
+				yyerror("first argument to append must be typed slice; have untyped nil", t);
+				goto error;
+			}
 			yyerror("first argument to append must be slice; have %lT", t);
 			goto error;
 		}