https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107939
--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-12 branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:19ed6bf44c3fec882cf4c825f3ffa4f2ecdc78e6 commit r12-9232-g19ed6bf44c3fec882cf4c825f3ffa4f2ecdc78e6 Author: Marek Polacek <pola...@redhat.com> Date: Fri Mar 3 11:24:24 2023 -0500 c++: error with constexpr operator() [PR107939] Similarly to PR107938, this also started with r11-557, whereby cp_finish_decl can call check_initializer even in a template for a constexpr initializer. Here we are rejecting extern const Q q; template<int> constexpr auto p = q(0); even though q has a constexpr operator(). It's deemed non-const by decl_maybe_constant_var_p because even though 'q' is const it is not of integral/enum type. If fun is not a function pointer, we don't know if we're using it as an lvalue or rvalue, so with this patch we pass 'any' for want_rval. With that, p_c_e/VAR_DECL doesn't flat out reject the underlying VAR_DECL. PR c++/107939 gcc/cp/ChangeLog: * constexpr.cc (potential_constant_expression_1) <case CALL_EXPR>: Pass 'any' when recursing on a VAR_DECL and not a pointer to function. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/var-templ74.C: Remove dg-error. * g++.dg/cpp1y/var-templ77.C: New test. (cherry picked from commit e09bc034d1b4d692b409fa5af52ae34480a6f4dc)
