gc: undo attempt at fixing recursive interface embedding

Fixes #582.

Update #287
Status: Accepted
Bug fix was too intrusive; undo and reopen issue.

R=ken2
CC=golang-dev
https://golang.org/cl/209044

src/cmd/gc/walk.c

@@ -122,9 +122,6 @@ walkdeflist(NodeList *l)
 		walkdef(l->n);
 }
 
-static NodeList *deftypequeue;
-static int intypedef;
-
 static void
 walkdeftype(Node *n)
 {
@@ -265,21 +262,7 @@ walkdef(Node *n)
 		n->walkdef = 1;
 		n->type = typ(TFORW);
 		n->type->sym = n->sym;
-		intypedef++;
+		walkdeftype(n);
-		if(intypedef > 1)
-			deftypequeue = list(deftypequeue, n);
-		else {
-			walkdeftype(n);
-			while(deftypequeue != nil) {
-				NodeList *l;
-				
-				l = deftypequeue;
-				deftypequeue = nil;
-				for(; l; l=l->next)
-					walkdeftype(l->n);
-			}
-		}
-		intypedef--;
 		break;
 
 	case OPACK:

test/fixedbugs/bug195.go

@@ -19,9 +19,9 @@ type I4 interface {
 }
 
 type I5 interface {
-	I6	// ERROR "interface"
+	I6
 }
 
 type I6 interface {
-	I5
+	I5	// ERROR "interface"
 }

test/fixedbugs/bug256.go

@@ -0,0 +1,16 @@
+// errchk $G -e $D/$F.go
+
+// Copyright 2010 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 T U	// bogus "invalid recursive type T" from 6g
+type U int
+
+const x T = 123
+
+type V V	// ERROR "invalid recursive type"
+
+

test/golden.out

@@ -150,3 +150,17 @@ throw: interface conversion
 panic PC=xxx
 
 == bugs/
+
+=========== bugs/bug250.go
+bugs/bug250.go:14: interface type loop involving I1
+bugs/bug250.go:17: need type assertion to use I2 as I1
+	missing m() I2
+BUG: bug250
+
+=========== bugs/bug251.go
+BUG: errchk: bugs/bug251.go:11: missing expected error: 'loop|interface'
+errchk: bugs/bug251.go: unmatched error messages:
+==================================================
+bugs/bug251.go:15: interface type loop involving I1
+bugs/bug251.go:19: need type assertion to use I2 as I1
+==================================================