https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94553
--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:54980635c537f3130481da2d8b1109c775db8bb0 commit r11-1714-g54980635c537f3130481da2d8b1109c775db8bb0 Author: Marek Polacek <pola...@redhat.com> Date: Fri Jun 26 12:40:59 2020 -0400 c++: Check uniqueness of concepts/variable templates [PR94553] This patch wraps up PR94553. Variable template names have no C compatibility implications so they should be unique in their declarative region. It occurred to me that this applies to concepts as well. This is not specified in [basic.scope.declarative]/4.2 but that seems like a bug in the standard. I couldn't use variable_template_p because that uses PRIMARY_TEMPLATE_P which uses DECL_PRIMARY_TEMPLATE and that might not have been set up yet (push_template_decl hasn't yet been called). PRIMARY_TEMPLATE_P is important to distinguish between a variable template and a variable in a function template. But I think we don't have to worry about that in duplicate_decls: a template declaration cannot appear at block scope, and additional checks in duplicate_decls suggest that it won't ever see a TEMPLATE_DECL for a variable in a function template. So checking that the DECL_TEMPLATE_RESULT is a VAR_DECL seems to be fine. I could have added a default argument to variable_template_p too to avoid checking PRIMARY_TEMPLATE_P but it didn't seem worth the effort. gcc/cp/ChangeLog: PR c++/94553 * decl.c (duplicate_decls): Make sure a concept or a variable template is unique in its declarative region. gcc/testsuite/ChangeLog: PR c++/94553 * g++.dg/cpp1y/pr68578.C: Adjust dg-error. * g++.dg/cpp1y/var-templ66.C: New test. * g++.dg/cpp2a/concepts-redecl1.C: New test.
