https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105848
--- 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:733a792a2b2e1662e738fa358b45a2720a8618a7 commit r13-995-g733a792a2b2e1662e738fa358b45a2720a8618a7 Author: Patrick Palka <ppa...@redhat.com> Date: Mon Jun 6 14:29:12 2022 -0400 c++: function NTTP argument considered unused [PR53164, PR105848] Here at parse time the template argument f (an OVERLOAD) in A<f> gets resolved ahead of time to the FUNCTION_DECL f<int>, and we defer marking f<int> as used until instantiation (of g) as usual. Later when instantiating g the type A<f> (where f has already been resolved) is non-dependent, so tsubst_aggr_type avoids re-processing its template arguments, and we end up never actually marking f<int> as used (which means we never instantiate it) even though A<f>::h() later calls it, leading to a link error. This patch works around this issue by looking through ADDR_EXPR when calling mark_used on the substituted callee of a CALL_EXPR. PR c++/53164 PR c++/105848 gcc/cp/ChangeLog: * pt.cc (tsubst_copy_and_build) <case CALL_EXPR>: Look through an ADDR_EXPR callee when calling mark_used. gcc/testsuite/ChangeLog: * g++.dg/template/fn-ptr3.C: New test.
