https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104752
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:97f76b5fc4b637033229e53033b4f8b6dc23472c commit r12-7600-g97f76b5fc4b637033229e53033b4f8b6dc23472c Author: Marek Polacek <pola...@redhat.com> Date: Wed Mar 2 12:12:33 2022 -0500 c++: Don't allow type-constraint auto(x) [PR104752] 104752 points out that template<class T> concept C = true; auto y = C auto(1); is ill-formed as per [dcl.type.auto.deduct]: "For an explicit type conversion, T is the specified type, which shall be auto." which doesn't allow type-constraint auto. PR c++/104752 gcc/cp/ChangeLog: * semantics.cc (finish_compound_literal): Disallow auto{x} for is_constrained_auto. * typeck2.cc (build_functional_cast_1): Likewise. gcc/testsuite/ChangeLog: * g++.dg/cpp23/auto-fncast12.C: New test.