cmd/gc: fix spurious 'not enough arguments to return' error

Fixes #6405

LGTM=rsc
R=rsc, iant
CC=golang-codereviews
https://golang.org/cl/72920046

diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index 5efc8d7913a21ccfd09398a5364054cf0d20a945..ebff0694a0670e7bd6a6d4ab105354c83873d83a 100644 (file)
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -1065,6 +1065,7 @@ reswitch:
                        goto reswitch;
                }
                typecheck(&n->left, Erv | Etype | Ecall |(top&Eproc));
+               n->diag |= n->left->diag;
                l = n->left;
                if(l->op == ONAME && l->etype != 0) {
                        if(n->isddd && l->etype != OAPPEND)
@@ -2165,6 +2166,7 @@ typecheckaste(int op, Node *call, int isddd, Type *tstruct, NodeList *nl, char *
        if(tstruct->broke)
                goto out;
 
+       n = N;
        if(nl != nil && nl->next == nil && (n = nl->n)->type != T)
        if(n->type->etype == TSTRUCT && n->type->funarg) {
                tn = n->type->type;
@@ -2239,10 +2241,14 @@ out:
        return;
 
 notenough:
-       if(call != N)
-               yyerror("not enough arguments in call to %N", call);
-       else
-               yyerror("not enough arguments to %O", op);
+       if(n == N || !n->diag) {
+               if(call != N)
+                       yyerror("not enough arguments in call to %N", call);
+               else
+                       yyerror("not enough arguments to %O", op);
+               if(n != N)
+                       n->diag = 1;
+       }
        goto out;
 
 toomany:

diff --git a/test/fixedbugs/issue6405.go b/test/fixedbugs/issue6405.go
new file mode 100644 (file)
index 0000000..b4551cc
--- /dev/null
+++ b/test/fixedbugs/issue6405.go
@@ -0,0 +1,13 @@
+// errorcheck
+
+// Copyright 2014 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.
+
+// Issue 6405: spurious 'not enough arguments to return' error
+
+package p
+
+func Open() (int, error) {
+       return OpenFile() // ERROR "undefined: OpenFile"
+}