Hi!
is_xible_helper returns error_mark_node (i.e. false from the traits)
for abstract classes by testing ABSTRACT_CLASS_TYPE_P (to) early.
Unfortunately, as the testcase shows, that doesn't work on class templates
that haven't been instantiated yet, ABSTRACT_CLASS_TYPE_P for them is false
until it is instantiated, which is done when the routine later constructs
a dummy object with that type.
The following patch fixes this by calling complete_type first, so that
ABSTRACT_CLASS_TYPE_P test will work properly, while keeping the handling
of arrays with unknown bounds, or incomplete types where it is done
currently.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2021-09-14 Jakub Jelinek <ja...@redhat.com>
PR c++/102305
* method.c (is_xible_helper): Call complete_type on to.
* g++.dg/cpp0x/pr102305.C: New test.
--- gcc/cp/method.c.jj 2021-08-12 09:34:16.465241411 +0200
+++ gcc/cp/method.c 2021-09-13 12:29:05.398000237 +0200
@@ -2081,6 +2081,7 @@ constructible_expr (tree to, tree from)
static tree
is_xible_helper (enum tree_code code, tree to, tree from, bool trivial)
{
+ to = complete_type (to);
deferring_access_check_sentinel acs (dk_no_deferred);
if (VOID_TYPE_P (to) || ABSTRACT_CLASS_TYPE_P (to)
|| (from && FUNC_OR_METHOD_TYPE_P (from)
--- gcc/testsuite/g++.dg/cpp0x/pr102305.C.jj 2021-09-13 12:46:47.580332966
+0200
+++ gcc/testsuite/g++.dg/cpp0x/pr102305.C 2021-09-13 12:49:00.072503394
+0200
@@ -0,0 +1,39 @@
+// PR c++/102305
+// { dg-do compile { target c++11 } }
+
+namespace std
+{
+ template<typename _Tp, _Tp __v>
+ struct integral_constant
+ {
+ static constexpr _Tp value = __v;
+ typedef integral_constant<_Tp, __v> type;
+ };
+
+ template<typename _Tp, _Tp __v>
+ constexpr _Tp integral_constant<_Tp, __v>::value;
+
+ typedef integral_constant<bool, true> true_type;
+ typedef integral_constant<bool, false> false_type;
+
+ template<bool __v>
+ using bool_constant = integral_constant<bool, __v>;
+
+ template<typename _Tp, typename... _Args>
+ struct is_constructible
+ : public bool_constant<__is_constructible(_Tp, _Args...)>
+ {
+ };
+}
+
+template<typename>
+struct A {
+ virtual ~A() = 0;
+};
+
+struct B {
+ virtual ~B() = 0;
+};
+
+static_assert(!std::is_constructible<A<int> >::value, "");
+static_assert(!std::is_constructible<B>::value, "");
Jakub
