https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41437
--- Comment #15 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:29853c653245c37ed31b6abcc9799b534372e938 commit r11-6800-g29853c653245c37ed31b6abcc9799b534372e938 Author: Patrick Palka <ppa...@redhat.com> Date: Tue Jan 19 16:20:00 2021 -0500 c++: Always check access during late-parsing of members [PR58993] This patch removes a vestigial use of dk_no_check from cp_parser_late_parsing_for_member, which ideally should have been removed as part of the PR41437 patch that improved access checking inside templates. This allows us to correctly reject f1 and f2 in the testcase access34.C below (whereas before we'd only reject f3). Additional testing revealed a new access issue when late-parsing a hidden friend within a class template. In the testcase friend68.C below, we're tripping over the checking assert from friend_accessible_p(f, S::j, S, S) during lookup of j in x.j (for which type_dependent_object_expression_p returns false, which is why we're doing the lookup at parse time). The reason for the assert failure is that DECL_FRIENDLIST(S) contains f but DECL_BEFRIENDING_CLASSES(f) is empty, and so friend_accessible_p (which looks at DECL_BEFRIENDING_CLASSES) wants to return false, but is_friend (which looks at DECL_FRIENDLIST) returns true. For sake of symmetry one would expect that DECL_BEFRIENDING_CLASSES(f) contains S, but add_friend avoids updating DECL_BEFRIENDING_CLASSES when the class type (S in this case) is dependent, for some reason. This patch works around this issue by making friend_accessible_p consider the DECL_FRIEND_CONTEXT of the access scope. Thus we sidestep the DECL_BEFRIENDING_CLASSES / DECL_FRIENDLIST asymmetry issue while correctly validating the x.j access at parse time. A earlier version of this patch checked friend_accessible_p instead of protected_accessible_p in the DECL_FRIEND_CONTEXT hunk below, but this had the side effect of making us accept the ill-formed testcase friend69.C below (ill-formed because the hidden friend g is not actually a member of A, so g doesn't have access to B's members despite B befriending A). gcc/cp/ChangeLog: PR c++/41437 PR c++/58993 * search.c (friend_accessible_p): If scope is a hidden friend defined inside a dependent class, consider access from the class. * parser.c (cp_parser_late_parsing_for_member): Don't push a dk_no_check access state. gcc/testsuite/ChangeLog: PR c++/41437 PR c++/58993 * g++.dg/opt/pr87974.C: Adjust. * g++.dg/template/access34.C: New test. * g++.dg/template/friend68.C: New test. * g++.dg/template/friend69.C: New test.
