https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92517
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jason Merrill <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:82aee6dd61e2a5b4e4b124f896c8403169688f41 commit r10-6506-g82aee6dd61e2a5b4e4b124f896c8403169688f41 Author: Jason Merrill <ja...@redhat.com> Date: Thu Feb 6 16:14:19 2020 -0500 c++: Fix ICE on nonsense requires-clause. Here we were swallowing all the syntax errors by parsing tentatively, and returning error_mark_node without ever actually giving an error. Fixed by using save_tokens/rollback_tokens instead. PR c++/92517 * parser.c (cp_parser_constraint_primary_expression): Do the main parse non-tentatively.