* call.c (convert_arg_to_ellipsis): Use the result of force_rvalue.

From-SVN: r253465

gcc/cp/ChangeLog

+2017-10-05  Jason Merrill  <jason@redhat.com>
+
+	* call.c (convert_arg_to_ellipsis): Use the result of force_rvalue.
+
 2017-10-05  Nathan Sidwell  <nathan@acm.org>
 
 	Warn on MVP declarations

gcc/cp/call.c

@@ -7165,29 +7165,24 @@ convert_arg_to_ellipsis (tree arg, tsubst_flags_t complain)
       /* In a template (or ill-formed code), we can have an incomplete type
 	 even after require_complete_type_sfinae, in which case we don't know
 	 whether it has trivial copy or not.  */
-      && COMPLETE_TYPE_P (arg_type))
+      && COMPLETE_TYPE_P (arg_type)
+      && !cp_unevaluated_operand)
     {
-      /* Build up a real lvalue-to-rvalue conversion in case the
-	 copy constructor is trivial but not callable.  */
-      if (!cp_unevaluated_operand && CLASS_TYPE_P (arg_type))
-	force_rvalue (arg, complain);
-
       /* [expr.call] 5.2.2/7:
 	 Passing a potentially-evaluated argument of class type (Clause 9)
 	 with a non-trivial copy constructor or a non-trivial destructor
 	 with no corresponding parameter is conditionally-supported, with
 	 implementation-defined semantics.
 
-	 We support it as pass-by-invisible-reference to the caller's
-	 object.  That's different to named by-value parameters, which
-	 construct a copy and pass a reference to that.
+	 We support it as pass-by-invisible-reference, just like a normal
+	 value parameter.
 
 	 If the call appears in the context of a sizeof expression,
 	 it is not potentially-evaluated.  */
-      if (cp_unevaluated_operand == 0
-	  && (type_has_nontrivial_copy_init (arg_type)
-	      || TYPE_HAS_NONTRIVIAL_DESTRUCTOR (arg_type)))
+      if (type_has_nontrivial_copy_init (arg_type)
+	  || TYPE_HAS_NONTRIVIAL_DESTRUCTOR (arg_type))
 	{
+	  arg = force_rvalue (arg, complain);
 	  if (complain & tf_warning)
 	    warning (OPT_Wconditionally_supported,
 		     "passing objects of non-trivially-copyable "
@@ -7195,6 +7190,11 @@ convert_arg_to_ellipsis (tree arg, tsubst_flags_t complain)
 		     arg_type);
 	  return cp_build_addr_expr (arg, complain);
 	}
+      /* Build up a real lvalue-to-rvalue conversion in case the
+	 copy constructor is trivial but not callable.  */
+      else if (CLASS_TYPE_P (arg_type))
+	force_rvalue (arg, complain);
+
     }
 
   return arg;

gcc/testsuite/g++.dg/ext/varargs2.C

+// { dg-do run }
+
+int c;
+struct X { X() {}; X(const X&) { ++c; } };
+void Foo (X, ...) {}
+void bin (X &p)
+{
+  Foo (p, p);
+}
+
+int main()
+{
+  X x;
+  bin(x);
+  if (c != 2)
+    __builtin_abort();
+}