https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97420
--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>: https://gcc.gnu.org/g:ad42219766d0e67bede2c9bd94c98082cde42518 commit r10-11482-gad42219766d0e67bede2c9bd94c98082cde42518 Author: Patrick Palka <ppa...@redhat.com> Date: Wed May 26 08:35:31 2021 -0400 c++: Fix reference NTTP binding to noexcept fn [PR97420] Here, in C++17 mode, convert_nontype_argument_function is rejecting binding a non-noexcept function reference template parameter to a noexcept function (encoded as the template argument '*(int (&) (int)) &f'). The first roadblock to making this work is that the argument is wrapped an an implicit INDIRECT_REF, so we need to unwrap it before calling strip_fnptr_conv. The second roadblock is that the NOP_EXPR cast converts from a function pointer type to a reference type while simultaneously removing the noexcept qualification, and fnptr_conv_p doesn't consider this cast to be a function pointer conversion. This patch fixes this by making fnptr_conv_p treat REFERENCE_TYPEs and POINTER_TYPEs interchangeably. Finally, in passing, this patch also simplifies noexcept_conv_p by removing a bunch of redundant checks already performed by its only caller fnptr_conv_p. PR c++/97420 gcc/cp/ChangeLog: * cvt.c (noexcept_conv_p): Remove redundant checks and simplify. (fnptr_conv_p): Don't call non_reference. Use INDIRECT_TYPE_P instead of TYPE_PTR_P. * pt.c (convert_nontype_argument_function): Look through implicit INDIRECT_REFs before calling strip_fnptr_conv. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/noexcept68.C: New test. (cherry picked from commit b4329e3dd6fb7c78948fcf9d2f5b9d873deec284)
