https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96106
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>: https://gcc.gnu.org/g:f31dd9beb95f4beda1d2bd5c0526c42d0ce455c4 commit r11-2418-gf31dd9beb95f4beda1d2bd5c0526c42d0ce455c4 Author: Patrick Palka <ppa...@redhat.com> Date: Wed Jul 29 22:06:36 2020 -0400 c++: abbreviated function template friend matching [PR96106] In the below testcase, duplicate_decls wasn't merging the tsubsted friend declaration for 'void add(auto)' with its definition, because reduce_template_parm_level (during tsubst_friend_function) lost the DECL_VIRTUAL_P flag on the auto's invented template parameter, which caused template_heads_equivalent_p to deem the two template heads as not equivalent in C++20 mode. This patch makes reduce_template_parm_level carry over the DECL_VIRTUAL_P flag from the original TEMPLATE_PARM_DECL. gcc/cp/ChangeLog: PR c++/96106 * pt.c (reduce_template_parm_level): Propagate DECL_VIRTUAL_P from the original TEMPLATE_PARM_DECL to the new lowered one. gcc/testsuite/ChangeLog: PR c++/96106 * g++.dg/concepts/abbrev7.C: New test.
