https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115754
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:1250540a98e0a1dfa4d7834672d88d8543ea70b1 commit r15-1795-g1250540a98e0a1dfa4d7834672d88d8543ea70b1 Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Jul 2 22:09:58 2024 +0200 c++: Fix ICE on constexpr placement new [PR115754] C++26 is making in P2747R2 paper placement new constexpr. While working on a patch for that, I've noticed we ICE starting with GCC 14 on the following testcase. The problem is that e.g. for the void * to sometype * casts checks, we really assume the casts have their operand constant evaluated as prvalue, but on the testcase the cast itself is evaluated with vc_discard and that means op can end up e.g. a VAR_DECL which the later code doesn't like and asserts on. If the result type is void, we don't really need the cast operand for anything, so can use vc_discard for the recursive call, VIEW_CONVERT_EXPR can appear on the lhs, so we need to honor the lval but otherwise the patch uses vc_prvalue. I'd like to get this patch in before the rest of P2747R2 implementation, so that it can be backported to 14.2 later on. 2024-07-02 Jakub Jelinek <ja...@redhat.com> Jason Merrill <ja...@redhat.com> PR c++/115754 * constexpr.cc (cxx_eval_constant_expression) <case CONVERT_EXPR>: For conversions to void, pass vc_discard to the recursive call and otherwise for tcode other than VIEW_CONVERT_EXPR pass vc_prvalue. * g++.dg/cpp26/pr115754.C: New test.
