cannot have interfaces refer to themselves as map keys

R=rsc
DELTA=11  (11 added, 0 deleted, 0 changed)
OCL=30774
CL=30774

test/bugs/bug165.go

@@ -0,0 +1,11 @@
+// errchk $G $D/$F.go
+
+// 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
+
+type I interface {
+	m(map[I] bool)
+}

test/golden.out

@@ -111,6 +111,10 @@ BUG: should not compile
 =========== bugs/bug164.go
 BUG: should not compile
 
+=========== bugs/bug165.go
+bugs/bug165.go:6: invalid map key type I
+BUG: should compile
+
 =========== fixedbugs/bug016.go
 fixedbugs/bug016.go:7: constant -3 overflows uint