This usage was intended to be allowed by P2128, but it didn't make it into
the final wording. Fixed by CWG 2507.
DR2507
gcc/cp/ChangeLog:
* decl.cc (grok_op_properties): Return sooner for C++23 op[].
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/subscript8.C: New test.
"operator ()". */
return true;
+ /* C++23 allows an arbitrary number of parameters and default arguments for
+ operator[], and none of the other checks below apply. */
+ if (operator_code == ARRAY_REF && cxx_dialect >= cxx23)
+ return true;
+
if (operator_code == COND_EXPR)
{
/* 13.4.0.3 */
{
if (!arg)
{
- /* Variadic. */
- if (operator_code == ARRAY_REF && cxx_dialect >= cxx23)
- break;
-
error_at (loc, "%qD must not have variable number of arguments",
decl);
return false;
case OVL_OP_FLAG_BINARY:
if (arity != 2)
{
- if (operator_code == ARRAY_REF && cxx_dialect >= cxx23)
- break;
error_at (loc,
methodp
? G_("%qD must have exactly one argument")
--- /dev/null
+// DR2507: Allow default arguments
+// { dg-additional-options {-std=c++23} }
+
+struct A
+{
+ void operator[](int, int = 42);
+};