https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96555
--- Comment #3 from CVS Commits ---
The master branch has been updated by Patrick Palka :
https://gcc.gnu.org/g:9b94785dedb08b006419bec1a402614d9241317a
commit r12-1093-g9b94785dedb08b006419bec1a402614d9241317a
Author: Patrick Palka
Date: Thu May 27 12:36:39 2021 -0400
c++: Relax rule for non-type arguments in partial specs [CWG1315]
This implements the wording changes of CWG 1315, which permits non-type
template arguments in a partial specialization to use template
parameters more freely. Delightfully, it seems the only change needed
is to remove a single check from process_partial_specialization (amidst
a bunch of whitespace changes).
But that change alone revealed a latent problem with
for_each_template_parm:
it ends up looking into some non-deduced contexts even when
include_nondeduced_p is false. This causes us to silently accept some
partial specializations within the testsuite that contain non-deducible
non-type template parameters (and that were previously rejected due to
the rule that CWG 1315 relaxed). For now this patch makes a minimal
amount of changes to for_each_template_parm_r so that we continue to
reject existing ill-formed partial specializations within the testsuite.
I opened PR c++/100779 to track this issue.
DR 1315
PR c++/67593
PR c++/96555
gcc/cp/ChangeLog:
* pt.c (process_partial_specialization): Don't error on a
non-simple non-type template argument that involves template
parameters.
(for_each_template_parm_r): Don't walk TRAIT_EXPR, PLUS_EXPR,
MULT_EXPR, or SCOPE_REF when include_nondeduced_p is false.
gcc/testsuite/ChangeLog:
* g++.dg/template/partial16.C: New test.
* g++.dg/template/partial17.C: New test.
* g++.dg/template/partial18.C: New test.
* g++.dg/template/partial19.C: New test.
* g++.dg/cpp0x/pr68724.C: Adjust expected diagnostic for
ill-formed partial specialization.
* g++.dg/cpp0x/variadic38.C: Likewise.
* g++.dg/cpp1z/pr81016.C: Likewise.
* g++.dg/template/partial5.C: Likewise.
* g++.old-deja/g++.pt/spec21.C: Likewise.
