https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112410
--- Comment #4 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:70060dadfbf0d0af5f4cab5f3aff3223a4523606 commit r14-5514-g70060dadfbf0d0af5f4cab5f3aff3223a4523606 Author: Marek Polacek <pola...@redhat.com> Date: Thu Nov 9 12:25:25 2023 -0500 c++: fix parsing with auto(x) [PR112410] Here we are wrongly parsing int y(auto(42)); which uses the C++23 cast-to-prvalue feature, and initializes y to 42. However, we were treating the auto as an implicit template parameter. Fixing the auto{42} case is easy, but when auto is followed by a (, I found the fix to be much more involved. For instance, we cannot use cp_parser_expression, because that can give hard errors. It's also necessary to disambiguate 'auto(i)' as 'auto i', not a cast. auto(), auto(int), auto(f)(int), auto(*), auto(i[]), auto(...), etc. are all function declarations. This patch rectifies that by undoing the implicit function template modification. In the test above, we should notice that the parameter list is ill-formed, and since we've synthesized an implicit template parameter, we undo it by calling abort_fully_implicit_template. Then, we'll parse the "(auto(42))" as an initializer. PR c++/112410 gcc/cp/ChangeLog: * parser.cc (cp_parser_direct_declarator): Maybe call abort_fully_implicit_template if it turned out the parameter list was ill-formed. gcc/testsuite/ChangeLog: * g++.dg/cpp23/auto-fncast13.C: New test. * g++.dg/cpp23/auto-fncast14.C: New test.
