gc: disallow invalid map keys

The algtype-based test broke when algtype
got a bit more fine-grained, so replace with
an explicit check for the invalid key types.

R=ken2
CC=golang-dev
https://golang.org/cl/5071041

src/cmd/gc/subr.c

@@ -548,9 +548,13 @@ maptype(Type *key, Type *val)
 {
 	Type *t;
 
-
-	if(key != nil && key->etype != TANY && algtype(key) == ANOEQ) {
-		if(key->etype == TFORW) {
+	if(key != nil) {
+		switch(key->etype) {
+		case TARRAY:
+		case TSTRUCT:
+			yyerror("invalid map key type %T", key);
+			break;
+		case TFORW:
 			// map[key] used during definition of key.
 			// postpone check until key is fully defined.
 			// if there are multiple uses of map[key]
@@ -559,8 +563,8 @@ maptype(Type *key, Type *val)
 			// good enough.
 			if(key->maplineno == 0)
 				key->maplineno = lineno;
-		} else
-			yyerror("invalid map key type %T", key);
+			break;
+		}
 	}
 	t = typ(TMAP);
 	t->down = key;

test/map1.go

@@ -0,0 +1,41 @@
+// errchk $G -e $D/$F.go
+
+// Copyright 2011 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() {}
+
+type v bool
+
+var (
+	// valid
+	_ map[int8]v 
+	_ map[uint8]v 
+	_ map[int16]v 
+	_ map[uint16]v 
+	_ map[int32]v 
+	_ map[uint32]v 
+	_ map[int64]v 
+	_ map[uint64]v 
+	_ map[int]v 
+	_ map[uint]v 
+	_ map[uintptr]v
+	_ map[float32]v
+	_ map[float64]v
+	_ map[complex64]v
+	_ map[complex128]v
+	_ map[bool]v
+	_ map[string]v
+	_ map[chan int]v
+	_ map[func()]v
+	_ map[*int]v
+	_ map[map[int]int]v
+
+	// invalid
+	_ map[struct{}]v // ERROR "invalid map key"
+	_ map[[]int]v  // ERROR "invalid map key"
+	_ map[[10]int]v // ERROR "invalid map key"
+)