https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68942
--- Comment #2 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:efeca0ac4155b76ce713155f190422aac20537c5 commit r12-295-gefeca0ac4155b76ce713155f190422aac20537c5 Author: Patrick Palka <ppa...@redhat.com> Date: Thu Apr 29 13:43:00 2021 -0400 c++: Overeager use of deleted function before ADL [PR68942] Here, at template definition time, ordinary name lookup for 'foo(t)' finds only the deleted function, and so we form a CALL_EXPR thereof. Later at instantiation time, when initially substituting into this CALL_EXPR with T=N::A, we end up calling mark_used on this deleted function (since it's the only function in the overload set), triggering a bogus "use of deleted function error", before we get to augment the overload set via ADL. This patch fixes this issue by using the tf_conv flag to disable mark_used during the initial substitution into the callee of a CALL_EXPR when KOENIG_P, since at this point we're still figuring out which functions are candidates. gcc/cp/ChangeLog: PR c++/68942 * pt.c (tsubst_copy_and_build) <case CALL_EXPR>: When KOENIG_P, set tf_conv during the initial substitution into the function. gcc/testsuite/ChangeLog: PR c++/68942 * g++.dg/template/koenig12.C: New test.
