https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94481
--- Comment #2 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:31449cf8e119bbe172a68689068591827472da5c commit r10-7608-g31449cf8e119bbe172a68689068591827472da5c Author: Jason Merrill <ja...@redhat.com> Date: Tue Apr 7 00:22:55 2020 -0400 c++: ICE on invalid concept placeholder [PR94481]. Here the 'decltype' is missing '(auto)', so open_paren was NULL, and trying to get its location is a SEGV. Using matching_parens avoids that problem. gcc/cp/ChangeLog 2020-04-07 Jason Merrill <ja...@redhat.com> PR c++/94481 * parser.c (cp_parser_placeholder_type_specifier): Use matching_parens.