gc: fix return variable named _

Fixes #1712.

R=ken2
CC=golang-dev
https://golang.org/cl/4445055

diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index 50cd0478677b08700b4983c1e46ee3bcb5896b51..bf164b3f43d80aece4ea8897acb37a44f30e675f 100644 (file)
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -560,6 +560,7 @@ funcargs(Node *nt)
 {
        Node *n;
        NodeList *l;
+       int gen;
 
        if(nt->op != OTFUNC)
                fatal("funcargs %O", nt->op);
@@ -589,6 +590,7 @@ funcargs(Node *nt)
        }
 
        // declare the out arguments.
+       gen = 0;
        for(l=nt->rlist; l; l=l->next) {
                n = l->n;
                if(n->op != ODCLFIELD)
@@ -596,6 +598,11 @@ funcargs(Node *nt)
                if(n->left != N) {
                        n->left->op = ONAME;
                        n->left->ntype = n->right;
+                       if(isblank(n->left)) {
+                               // Give it a name so we can assign to it during return.
+                               snprint(namebuf, sizeof(namebuf), ".anon%d", gen++);
+                               n->left->sym = lookup(namebuf);
+                       }
                        declare(n->left, PPARAMOUT);
                }
        }

diff --git a/test/fixedbugs/bug331.go b/test/fixedbugs/bug331.go
new file mode 100644 (file)
index 0000000..28aee1d
--- /dev/null
+++ b/test/fixedbugs/bug331.go
@@ -0,0 +1,36 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out || echo BUG: bug331
+
+// 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
+
+import "os"
+
+func f() (_ string, x float64, err os.Error) {
+       return
+}
+
+func g() (_ string, x float64, err os.Error) {
+       return "hello", 3.14, os.EOF
+}
+
+var _ func() (string, float64, os.Error) = f
+var _ func() (string, float64, os.Error) = g
+
+func main() {
+       x, y, z := g()
+       if x != "hello" || y != 3.14 || z != os.EOF {
+               println("wrong", x, len(x), y, z)
+       }
+}
+
+/*
+issue 1712
+
+bug331.go:12: cannot use "hello" (type string) as type float64 in assignment
+bug331.go:12: cannot use 0 (type float64) as type os.Error in assignment:
+       float64 does not implement os.Error (missing String method)
+bug331.go:12: error in shape across RETURN
+*/