https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116384
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-14 branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:52da8588fd06198edcda81d7acf83ec92ccb63ef commit r14-10603-g52da8588fd06198edcda81d7acf83ec92ccb63ef Author: Marek Polacek <pola...@redhat.com> Date: Thu Aug 15 11:53:10 2024 -0400 c++: fix ICE in convert_nontype_argument [PR116384] Here we ICE since r14-8291 in C++11/C++14 modes. Fortunately this is an easy one. The important bit of r14-8291 is this: @@ -20056,9 +20071,12 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl) RETURN (retval); } if (IMPLICIT_CONV_EXPR_NONTYPE_ARG (t)) - /* We'll pass this to convert_nontype_argument again, we don't need - to actually perform any conversion here. */ - RETURN (expr); + { + tree r = convert_nontype_argument (type, expr, complain); + if (r == NULL_TREE) + r = error_mark_node; + RETURN (r); + } which obviously means that instead of returning right away we go to convert_nontype_argument. When type is error_mark_node and we're in C++17, in convert_nontype_argument we go down this path: else if (INTEGRAL_OR_ENUMERATION_TYPE_P (type) || cxx_dialect >= cxx17) { expr = build_converted_constant_expr (type, expr, complain); if (expr == error_mark_node) return (complain & tf_error) ? NULL_TREE : error_mark_node; // ... } but pre-C++17, we take a different route and end up crashing on gcc_unreachable. It would of course also work to check for error_mark_node early in build_converted_constant_expr. PR c++/116384 gcc/cp/ChangeLog: * pt.cc (tsubst_expr) <case IMPLICIT_CONV_EXPR>: Bail if tsubst returns error_mark_node. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/vt-116384.C: New test. (cherry picked from commit 8191f15022b0ea44fcb549449b0458d07ae02e0a)
