https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120685
--- Comment #11 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-14 branch has been updated by Jakub Jelinek <[email protected]>: https://gcc.gnu.org/g:19653eac71b9f553e40a73e20d32bcb18b1f1f04 commit r14-12410-g19653eac71b9f553e40a73e20d32bcb18b1f1f04 Author: Jakub Jelinek <[email protected]> Date: Tue Feb 17 08:59:06 2026 +0100 c++: Don't support auto{x} and auto(x) for C++ < 23 in SFINAE contexts [PR120685] The following testcase ICEs in C++ 20 and older, because during diagnostics dump_template_bindings attempts to tsubst with tf_none something and we try to emit a pedwarn during that. While the pedwarn could be just guarded with if (complain & tf_warning), I thought we shouldn't support extensions for tf_none and should instead return error_mark_node. The following patch does that. This is a backport version which instead of not supporting it just doesn't emit the pedwarn in SFINAE contexts for C++ < 23 but still supports it. 2026-02-17 Jakub Jelinek <[email protected]> PR c++/120685 * typeck2.cc (build_functional_cast_1): For C++23 auto(x) without tf_warning or tf_error return error_mark_node instead of emitting pedwarn and handling it. * semantics.cc (finish_compound_literal): Similarly for C++26 auto{x}. * g++.dg/cpp23/auto-fncast19.C: New test. (cherry picked from commit f7efb7e62ac96c082ff72549d9b3789f5c955efe)
