slice doesn't work on a string literal

SVN=125259

test/bugs/bug061.go

+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 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.
+
+package main
+
+func main() {
+	var s string;
+	s = "0000000000000000000000000000000000000000000000000000000000"[0:7];
+}

test/golden.out

@@ -312,6 +312,12 @@ BUG: crashes
 =========== bugs/bug060.go
 BUG: crashes
 
+=========== bugs/bug061.go
+bugs/bug061.go:7: illegal types for operand: SLICE
+bugs/bug061.go:7: illegal types for operand: AS
+	(<string>*STRING)
+BUG: known to fail incorrectly
+
 =========== fixedbugs/bug000.go
 
 =========== fixedbugs/bug001.go