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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/102412] Template argument deduction fails when using concept as defaulted non-type template parameter
Date: Wed, 06 Oct 2021 14:15:36 +0000 [thread overview]
Message-ID: <bug-102412-4-YRp0j6aCIZ@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-102412-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102412
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:
https://gcc.gnu.org/g:5a411459b73b65d8a1235a16d6e2aac4eed17338
commit r11-9082-g5a411459b73b65d8a1235a16d6e2aac4eed17338
Author: Patrick Palka <ppalka@redhat.com>
Date: Wed Sep 22 11:16:53 2021 -0400
c++: concept-ids and value-dependence [PR102412]
The problem here is that uses_template_parms returns true for all
concept-ids (even those with non-dependent arguments), so when a concept-id
is used as a default template argument then during deduction the default
argument is considered dependent even after substituting into it, which
leads to deduction failure (from type_unification_real).
This patch fixes this by implementing the resolution of CWG 2446 which
says a concept-id is dependent only if its arguments are.
DR 2446
PR c++/102412
gcc/cp/ChangeLog:
* constexpr.c (cxx_eval_constant_expression)
<case TEMPLATE_ID_EXPR>: Check value_dependent_expression_p
instead of processing_template_decl.
* pt.c (value_dependent_expression_p) <case TEMPLATE_ID_EXPR>:
Return true only if any_dependent_template_arguments_p.
(instantiation_dependent_r) <case CALL_EXPR>: Remove this case.
<case TEMPLATE_ID_EXPR>: Likewise.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-nondep2.C: New test.
* g++.dg/cpp2a/concepts-nondep3.C: New test.
(cherry picked from commit 9329344a6d81a6a5e3bd171167ebc7b158bb44f4)
next prev parent reply other threads:[~2021-10-06 14:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 16:45 [Bug c++/102412] New: " joeloser93 at gmail dot com
2021-09-20 18:36 ` [Bug c++/102412] " ppalka at gcc dot gnu.org
2021-09-22 15:18 ` cvs-commit at gcc dot gnu.org
2021-10-06 14:15 ` cvs-commit at gcc dot gnu.org [this message]
2021-10-06 14:19 ` ppalka at gcc dot gnu.org
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