https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102921
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-10-25
CC| |jakub at gcc dot gnu.org,
| |jason at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Testcase without headers:
namespace std
{
typedef decltype (sizeof 0) size_t;
template<class T>
class initializer_list
{
const T *_M_array;
size_t _M_len;
constexpr initializer_list (const T &a, size_t l) : _M_array(a), _M_len(l)
{ }
};
}
struct S
{
constexpr S () noexcept { }
int a = __builtin_is_constant_evaluated ();
};
constexpr std::initializer_list <S> a { { } };
The <temporary> is _ZGRL1a_[0] demangled reference temporary #0 for a, and the
expression that is being constant evaluated is (without cleanup points and
expr_stmt):
TARGET_EXPR <D.2197, {._M_array= (_ZGRL1a_[0] = TARGET_EXPR <D.2186, S::S
(&D.2186)>;, (const struct S *) &_ZGRL1a_;, ._M_len=1}>;
No idea how to fix that though...
Doesn't seem to be a regression, behaved this way since
r9-2311-ge408261123697a82b5965c700fa2465999f0fd62 when
__builtin_is_constant_evaluated has been introduced.
Without the builtin, bet the ctor is folded into a CONSTRUCTOR already when
performing non-manifestly constant evaluation before.
The INIT_EXPR that stores into _ZGRL1a_[0] is created by
split_nonconstant_init_1 called indirectly from set_up_extended_ref_temp, so at
that point the initializer clearly didn't go through manifestly constant
evaluation. Should that be done somewhere if set_up_extended_ref_temp is
called for a constexpr variable?
