https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83258
--- Comment #13 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:c3afdb8ba8f1839544c414f57e41a58c8fda5349 commit r14-708-gc3afdb8ba8f1839544c414f57e41a58c8fda5349 Author: Patrick Palka <ppa...@redhat.com> Date: Thu May 11 10:04:25 2023 -0400 c++: converted lambda as template argument [PR83258, ...] r8-1253-g3d2e25a240c711 removed the template argument linkage requirement in convert_nontype_argument for C++17 (which r9-3836-g4be5c72cf3ea3e later factored out into invalid_tparm_referent_p), but we need to also remove the one in convert_nontype_argument_function for benefit of the first and third testcase which we currently reject even in C++17/20 mode. And in invalid_tparm_referent_p we're inadvertendly returning false for the address of a lambda's static op() since it's DECL_ARTIFICIAL, which currently causes us to reject the second (C++20) testcase. But this DECL_ARTIFICIAL check seems to be relevant only for VAR_DECL, and in fact this code path was originally reachable only for VAR_DECL until recently (r13-6970-gb5e38b1c166357). So this patch restricts the check to VAR_DECL. Co-authored-by: Jonathan Wakely <jwak...@redhat.com> PR c++/83258 PR c++/80488 PR c++/97700 gcc/cp/ChangeLog: * pt.cc (convert_nontype_argument_function): Remove linkage requirement for C++17 and later. (invalid_tparm_referent_p) <case ADDR_EXPR>: Restrict DECL_ARTIFICIAL rejection test to VAR_DECL. gcc/testsuite/ChangeLog: * g++.dg/ext/visibility/anon8.C: Don't expect a "no linkage" error for the template argument &B2:fn in C++17 mode. * g++.dg/cpp0x/lambda/lambda-conv15.C: New test. * g++.dg/cpp2a/nontype-class56.C: New test. * g++.dg/template/function2.C: New test.