From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1888) id B7B3C388A825; Thu, 24 Jun 2021 17:13:44 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B7B3C388A825 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Patrick Palka To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-1793] c++: alias CTAD and aggregate deduction cand [PR98832] X-Act-Checkin: gcc X-Git-Author: Patrick Palka X-Git-Refname: refs/heads/master X-Git-Oldrev: c06493dc30afbf65b14d783c7cd53f20877ef577 X-Git-Newrev: c761be53f6b62e22ac5de18c4aaf88648f64f5b7 Message-Id: <20210624171344.B7B3C388A825@sourceware.org> Date: Thu, 24 Jun 2021 17:13:44 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 24 Jun 2021 17:13:44 -0000 https://gcc.gnu.org/g:c761be53f6b62e22ac5de18c4aaf88648f64f5b7 commit r12-1793-gc761be53f6b62e22ac5de18c4aaf88648f64f5b7 Author: Patrick Palka Date: Thu Jun 24 13:11:44 2021 -0400 c++: alias CTAD and aggregate deduction cand [PR98832] During alias CTAD, we're accidentally ignoring the aggregate deduction candidate for the underlying template because this guide is added separately via maybe_aggr_guide (which doesn't yet handle alias templates) instead of via deduction_guides_for (which does). This patch makes maybe_aggr_guide handle alias templates in a manner similar to deduction_guides_for. PR c++/98832 gcc/cp/ChangeLog: * pt.c (maybe_aggr_guide): Handle alias templates appropriately. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/class-deduction-alias9.C: New test. Diff: --- gcc/cp/pt.c | 11 +++++++++++ gcc/testsuite/g++.dg/cpp2a/class-deduction-alias9.C | 6 ++++++ 2 files changed, 17 insertions(+) diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 1af81208e26..f73c7471a33 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -28886,6 +28886,8 @@ is_spec_or_derived (tree etype, tree tmpl) return !err; } +static tree alias_ctad_tweaks (tree, tree); + /* Return a C++20 aggregate deduction candidate for TYPE initialized from INIT. */ @@ -28898,6 +28900,15 @@ maybe_aggr_guide (tree tmpl, tree init, vec *args) if (init == NULL_TREE) return NULL_TREE; + if (DECL_ALIAS_TEMPLATE_P (tmpl)) + { + tree under = DECL_ORIGINAL_TYPE (DECL_TEMPLATE_RESULT (tmpl)); + tree tinfo = get_template_info (under); + if (tree guide = maybe_aggr_guide (TI_TEMPLATE (tinfo), init, args)) + return alias_ctad_tweaks (tmpl, guide); + return NULL_TREE; + } + /* We might be creating a guide for a class member template, e.g., template struct A { diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias9.C b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias9.C new file mode 100644 index 00000000000..5cc7b7c1a80 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias9.C @@ -0,0 +1,6 @@ +// PR c++/98832 +// { dg-do compile { target c++20 } } + +template struct X { U u; }; +template using Y = X; +Y y{0};