This patch implements the proposed resolution of
https://cplusplus.github.io/LWG/issue4477
The PR complains that one can't successfully throw from constructor
in placement new in a constant expression and catch that exception
later on. The problem is while P2747R2 made placement ::operator new
and ::operator new[] constexpr, when the ctor throws it invokes also
these weird placement ::operator delete and ::operator delete[]
which intentionally perform no action, and those weren't constexpr,
so constant expression evaluation failed.
2025-11-19 Jakub Jelinek <jakub@redhat.com>
PR libstdc++/122671
* libsupc++/new (::operator delete, ::operator delete[]): Implement
proposed LWG4477 resolution. Use _GLIBCXX_PLACEMENT_CONSTEXPR for
placement operator deletes.
* g++.dg/cpp26/constexpr-eh17.C: New test.
5294e0a0b4