On 4/25/24 07:22, Jakub Jelinek wrote:
On Thu, Apr 25, 2024 at 02:02:32PM +0200, Jakub Jelinek wrote:
I've tried the following patch, but unfortunately that lead to large
number of regressions:
+FAIL: g++.dg/cpp0x/initlist25.C -std=c++17 (test for excess errors)
So the reduced testcase for this is
template <typename T, typename U> struct A {
T a1;
U a2;
template <typename V, typename W, bool = true>
constexpr A(V &&x, W &&y) : a1(x), a2(y) {}
};
template <typename> struct B;
namespace std {
template <class> struct initializer_list {
int *_M_array;
decltype (sizeof 0) _M_len;
};
}
template <typename T, typename U> struct C {
void foo (std::initializer_list<A<const T, U>>);
};
template <class> struct D;
template <typename T, typename = D<T>, typename = B<T>>
struct E { E (const char *); ~E (); };
int
main ()
{
C<E<char>, E<char>> m;
m.foo ({{"t", "t"}, {"y", "y"}});
}
Without the patch I've just posted or even with the earlier version
of the patch the
_ZN1AIK1EIc1DIcE1BIcEES5_EC[12]IRA2_KcSB_Lb1EEEOT_OT0_
ctors were emitted, but with this patch they are unresolved externals.
The reason is that the code actually uses (calls) the
_ZN1AIK1EIc1DIcE1BIcEES5_EC1IRA2_KcSB_Lb1EEEOT_OT0_
__ct_comp constructor, that one has TREE_USED, while the
_ZN1AIK1EIc1DIcE1BIcEES5_EC2IRA2_KcSB_Lb1EEEOT_OT0_
__ct_base constructor is not TREE_USED.
But the c_parse_final_cleanups loop over
FOR_EACH_VEC_SAFE_ELT (deferred_fns, i, decl)
will ignore the TREE_USED __ct_comp because it is an alias
and so has !DECL_SAVED_TREE:
5273 if (!DECL_SAVED_TREE (decl))
5274 continue;
Hmm, maybe maybe_clone_body shouldn't clear DECL_SAVED_TREE for aliases,
but rather set it to some stub like void_node?
Though with all these changes, it's probably better to go with your
first patch for GCC 14 and delay this approach to 15. Your v1 patch is
OK for 14.
Jason
