gc: bug293

Fixes #846.

R=ken2
CC=golang-dev
https://golang.org/cl/1862042

src/cmd/5g/ggen.c

@@ -87,12 +87,12 @@ compile(Node *fn)
 
 	if(pret)
 		patch(pret, pc);
+	if(hasdefer)
+		ginscall(deferreturn, 0);
 	if(curfn->exit)
 		genlist(curfn->exit);
 	if(nerrors != 0)
 		goto ret;
-	if(hasdefer)
-		ginscall(deferreturn, 0);
 	pc->as = ARET;	// overwrite AEND
 	pc->lineno = lineno;
 

src/cmd/6g/ggen.c

@@ -90,13 +90,13 @@ compile(Node *fn)
 	if(pret)
 		patch(pret, pc);
 	ginit();
+	if(hasdefer)
+		ginscall(deferreturn, 0);
 	if(curfn->exit)
 		genlist(curfn->exit);
 	gclean();
 	if(nerrors != 0)
 		goto ret;
-	if(hasdefer)
-		ginscall(deferreturn, 0);
 	pc->as = ARET;	// overwrite AEND
 	pc->lineno = lineno;
 

src/cmd/8g/ggen.c

@@ -92,11 +92,6 @@ compile(Node *fn)
 	if(pret)
 		patch(pret, pc);
 	ginit();
-	if(curfn->exit)
-		genlist(curfn->exit);
-	gclean();
-	if(nerrors != 0)
-		goto ret;
 	if(hasdefer) {
 		// On Native client, insert call to no-op function
 		// to force alignment immediately before call to deferreturn,
@@ -107,6 +102,11 @@ compile(Node *fn)
 			ginscall(naclnop, 0);
 		ginscall(deferreturn, 0);
 	}
+	if(curfn->exit)
+		genlist(curfn->exit);
+	gclean();
+	if(nerrors != 0)
+		goto ret;
 	pc->as = ARET;	// overwrite AEND
 	pc->lineno = lineno;
 

src/cmd/gc/walk.c

@@ -365,7 +365,7 @@ walkstmt(Node **np)
 	NodeList *init;
 	NodeList *ll, *rl;
 	int cl, lno;
-	Node *n;
+	Node *n, *f;
 
 	n = *np;
 	if(n == N)
@@ -492,6 +492,14 @@ walkstmt(Node **np)
 				n->list = nil;
 				break;
 			}
+			if(count(n->list) == 1 && count(rl) > 1) {
+				// OAS2FUNC in disguise
+				f = n->list->n;
+				if(f->op != OCALLFUNC && f->op != OCALLMETH && f->op != OCALLINTER)
+					fatal("expected return of call, have %#N", f);
+				n->list = concat(list1(f), ascompatet(n->op, rl, &f->type, 0, &n->ninit));
+				break;
+			}
 			ll = ascompatee(n->op, rl, n->list, &n->ninit);
 			n->list = reorder3(ll);
 			break;

test/fixedbugs/bug293.go

+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// 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.
+
+// http://code.google.com/p/go/issues/detail?id=846
+
+package main
+
+func x() (a int, b bool) {
+	defer func(){
+		a++
+	}()
+	a, b = y()
+	return
+}
+
+func x2() (a int, b bool) {
+	defer func(){
+		a++
+	}()
+	return y()
+}
+
+func y() (int, bool) {
+	return 4, false
+}
+
+func main() {
+	if a, _ := x(); a != 5 {
+		println("BUG", a)
+	}
+	if a, _ := x2(); a != 5 {
+		println("BUG", a)
+	}
+}