https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113835
--- Comment #4 from Patrick Palka <ppalka at gcc dot gnu.org> --- r13-6421 just makes us use mce_true and mce_uknown during trial constant evaluation of x's initialization, so my guess is before that commit the evaluation was quickly aborted as soon as it saw a std::is_constant_evaluated() call, and afterwards we evaluate is_constant_evaluated() to true and keep going until we hit constexpr_loop_limit / constexpr_ops_limit. So perhaps we should have reduced limits for trial constant evaluation?
