https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93557
--- Comment #3 from CVS 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:5a8ad97b6e4823d4ded00a3ce8d80e4bf93368d4 commit r10-6460-g5a8ad97b6e4823d4ded00a3ce8d80e4bf93368d4 Author: Jakub Jelinek <ja...@redhat.com> Date: Wed Feb 5 23:35:08 2020 +0100 c++: Mark __builtin_convertvector operand as read [PR93557] In C++ we weren't calling mark_exp_read on the __builtin_convertvector first argument. I guess it could misbehave even with lambda implicit captures. Fixed by calling decay_conversion on the argument, we use the argument as rvalue so we want the standard lvalue to rvalue conversions, but as the argument must be a vector type, e.g. integral promotions aren't really needed. 2020-02-05 Jakub Jelinek <ja...@redhat.com> PR c++/93557 * semantics.c (cp_build_vec_convert): Call decay_conversion on arg prior to passing it to c_build_vec_convert. * c-c++-common/Wunused-var-17.c: New test.