https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111132
--- Comment #7 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-13 branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:294140d752fc9a3a790497da9f1e968e9849b40f commit r13-9296-g294140d752fc9a3a790497da9f1e968e9849b40f Author: Marek Polacek <pola...@redhat.com> Date: Tue Apr 2 12:59:38 2024 -0400 c++: constexpr error with fn redecl in local scope [PR111132] We evaluate constexpr functions on the original, pre-genericization bodies. That means that the function body we're evaluating will not have gone through cp_genericize_r's "Map block scope extern declarations to visible declarations with the same name and type in outer scopes if any". Here: constexpr bool bar() { return true; } // #1 constexpr bool foo() { constexpr bool bar(void); // #2 return bar(); } it means that we: 1) register_constexpr_fundef (#1) 2) cp_genericize (#1) nothing interesting happens 3) register_constexpr_fundef (foo) does copy_fn, so we have two copies of the BIND_EXPR 4) cp_genericize (foo) this remaps #2 to #1, but only on one copy of the BIND_EXPR 5) retrieve_constexpr_fundef (foo) we find it, no problem 6) retrieve_constexpr_fundef (#2) and here #2 isn't found in constexpr_fundef_table, because we're working on the BIND_EXPR copy where #2 wasn't mapped to #1 so we fail. We've only registered #1. It should work to use DECL_LOCAL_DECL_ALIAS (which used to be extern_decl_map). We evaluate constexpr functions on pre-cp_fold bodies to avoid diagnostic problems, but the remapping I'm proposing should not interfere with diagnostics. This is not a problem for a global scope redeclaration; there we go through duplicate_decls which keeps the DECL_UID: DECL_UID (olddecl) = olddecl_uid; and DECL_UID is what constexpr_fundef_hasher::hash uses. PR c++/111132 gcc/cp/ChangeLog: * constexpr.cc (get_function_named_in_call): Use cp_get_fndecl_from_callee. * cvt.cc (cp_get_fndecl_from_callee): If there's a DECL_LOCAL_DECL_ALIAS, use it. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/constexpr-redeclaration3.C: New test. * g++.dg/cpp0x/constexpr-redeclaration4.C: New test. (cherry picked from commit 8c9063825ce726fcbbc067d8a6d062cc2d4acf5e)
