From 9efd6b8a3d4d9b8336abf37d63487aded193b8b2 Mon Sep 17 00:00:00 2001
From: Ken Thompson <ken@golang.org>
Date: Thu, 2 Apr 2009 18:06:43 -0700
Subject: [PATCH] compiler falut for forgetting the assignment on a type switch

R=r
OCL=27048
CL=27048
---
 src/cmd/gc/swt.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/cmd/gc/swt.c b/src/cmd/gc/swt.c
index 70d1a9e477..263496701f 100644
--- a/src/cmd/gc/swt.c
+++ b/src/cmd/gc/swt.c
@@ -763,6 +763,13 @@ typeswitch(Node *sw)
 	Case *c, *c0, *c1;
 	int ncase;
 
+	if(sw->ntest == nil)
+		return;
+	if(sw->ntest->right == nil) {
+		setlineno(sw);
+		yyerror("type switch must have an assignment");
+		return;
+	}
 	walktype(sw->ntest->right, Erv);
 	if(!istype(sw->ntest->right->type, TINTER)) {
 		yyerror("type switch must be on an interface");
-- 
2.48.1