gc: do not compile switch on interface values into a binary search.

Fixes #2672.

R=golang-dev, lvd
CC=golang-dev, remy
https://golang.org/cl/5543058

diff --git a/src/cmd/gc/swt.c b/src/cmd/gc/swt.c
index 8b1b93c7dad9e19bc67a44d1db5d4f957206378c..6c0a9ac832f44f11a3ae81365e82f82feec9b30e 100644 (file)
--- a/src/cmd/gc/swt.c
+++ b/src/cmd/gc/swt.c
@@ -540,7 +540,7 @@ loop:
        }
 
        // deal with the variables one-at-a-time
-       if(c0->type != Texprconst) {
+       if(!okforcmp[t->etype] || c0->type != Texprconst) {
                a = exprbsw(c0, 1, arg);
                cas = list(cas, a);
                c0 = c0->link;

diff --git a/test/fixedbugs/bug393.go b/test/fixedbugs/bug393.go
new file mode 100644 (file)
index 0000000..e21b9c4
--- /dev/null
+++ b/test/fixedbugs/bug393.go
@@ -0,0 +1,30 @@
+// $G $D/$F.go || echo BUG: bug393
+
+// Copyright 2012 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 2672
+// was trying binary search with an interface type
+
+package main
+
+func f(x interface{}) int {
+       switch x {
+       case 1:
+               return 1
+       case 2:
+               return 2
+       case 3:
+               return 3
+       case 4:
+               return 4
+       case "5":
+               return 5
+       case "6":
+               return 6
+       default:
+               return 7
+       }
+       panic("switch")
+}