{"id":2224709,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2224709/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260417202807.373863-1-polacek@redhat.com/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/1.1/projects/17/?format=json","name":"GNU Compiler Collection","link_name":"gcc","list_id":"gcc-patches.gcc.gnu.org","list_email":"gcc-patches@gcc.gnu.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20260417202807.373863-1-polacek@redhat.com>","date":"2026-04-17T20:28:07","name":"c++/reflection: support splices with CTAD [PR124706]","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"9a24dbf3806ad3de50caefd2589751bfe0662690","submitter":{"id":14370,"url":"http://patchwork.ozlabs.org/api/1.1/people/14370/?format=json","name":"Marek Polacek","email":"polacek@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260417202807.373863-1-polacek@redhat.com/mbox/","series":[{"id":500399,"url":"http://patchwork.ozlabs.org/api/1.1/series/500399/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=500399","date":"2026-04-17T20:28:07","name":"c++/reflection: support splices with CTAD [PR124706]","version":1,"mbox":"http://patchwork.ozlabs.org/series/500399/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2224709/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2224709/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","gcc-patches@gcc.gnu.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","gcc-patches@gcc.gnu.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=IRL9K8JQ;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; 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a=rsa-sha256; c=relaxed/relaxed; d=redhat.com;\n s=mimecast20190719; t=1776457695;\n h=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n to:to:cc:mime-version:mime-version:content-type:content-type:\n content-transfer-encoding:content-transfer-encoding;\n bh=WbJmEEPzTYcP4Yq08BclKdX1aHFO7v9CNJDfUlDlqz0=;\n b=IRL9K8JQ/c99U6NI6qXYwqZ6AUclkJUFPcefaruU404L9U9OogO2y3xtN3pfX/TJlcGqVm\n zqsnIE0JVlrxktPmKaOnQkgETn9z57FkNDtDY6BN7WQ5vncNgzjnnG2MynYMXOuI5DykJn\n y03fVaXZEb8LvYgIGO0IHAugORn0zVs=","X-MC-Unique":"HRKVH35SPbm7Xv4DKtIRAA-1","X-Mimecast-MFC-AGG-ID":"HRKVH35SPbm7Xv4DKtIRAA_1776457693","From":"Marek Polacek ","To":"GCC Patches ,\n\tJason Merrill ","Subject":"[PATCH] c++/reflection: support splices with CTAD [PR124706]","Date":"Fri, 17 Apr 2026 16:28:07 -0400","Message-ID":"<20260417202807.373863-1-polacek@redhat.com>","MIME-Version":"1.0","X-Scanned-By":"MIMEDefang 3.4.1 on 10.30.177.93","X-Mimecast-Spam-Score":"0","X-Mimecast-MFC-PROC-ID":"HqgRfaahma6Q1fgTie7ki3xnv9D8sB-pbBCkqtreVxg_1776457693","X-Mimecast-Originator":"redhat.com","Content-Transfer-Encoding":"8bit","content-type":"text/plain; charset=\"US-ASCII\"; x-default=true","X-BeenThere":"gcc-patches@gcc.gnu.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Gcc-patches mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org"},"content":"Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?\n\n-- >8 --\nThis PR points out that we don't handle a splice-type-spec that\ndesignates a deducible template, which then serves as a placeholder\nfor CTAD. This is allowed by [dcl.type.simple]/3. This patch\nfixes that problem by calling make_template_placeholder if we\nget a deducible template.\n\n\tPR c++/124706\n\ngcc/cp/ChangeLog:\n\n\t* parser.cc (cp_parser_splice_type_specifier): For ctad_template_p\n\tcall make_template_placeholder.\n\ngcc/testsuite/ChangeLog:\n\n\t* g++.dg/reflect/error10.C: Adjust dg-error.\n\t* g++.dg/reflect/ctad1.C: New test.\n\t* g++.dg/reflect/ctad2.C: New test.\n---\n gcc/cp/parser.cc | 6 ++++++\n gcc/testsuite/g++.dg/reflect/ctad1.C | 13 +++++++++++++\n gcc/testsuite/g++.dg/reflect/ctad2.C | 24 ++++++++++++++++++++++++\n gcc/testsuite/g++.dg/reflect/error10.C | 5 ++---\n 4 files changed, 45 insertions(+), 3 deletions(-)\n create mode 100644 gcc/testsuite/g++.dg/reflect/ctad1.C\n create mode 100644 gcc/testsuite/g++.dg/reflect/ctad2.C\n\n\nbase-commit: 957c1153f5eedbbab8be92c5805d2cf53a84b204","diff":"diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc\nindex cc59065848a..9f2641f2ab2 100644\n--- a/gcc/cp/parser.cc\n+++ b/gcc/cp/parser.cc\n@@ -6258,6 +6258,12 @@ cp_parser_splice_type_specifier (cp_parser *parser)\n if (dependent_splice_p (type))\n return make_splice_scope (type, /*type_p=*/true);\n \n+ /* [dcl.type.simple]/3: A type-specifier is a placeholder for a deduced\n+ class type if [...] it is of the form typename[opt] splice-specifier and\n+ the splice-specifier designates a class template or alias template. */\n+ if (ctad_template_p (type))\n+ type = make_template_placeholder (type);\n+\n if (!valid_splice_type_p (type))\n {\n if (!cp_parser_simulate_error (parser))\ndiff --git a/gcc/testsuite/g++.dg/reflect/ctad1.C b/gcc/testsuite/g++.dg/reflect/ctad1.C\nnew file mode 100644\nindex 00000000000..5358b584bc8\n--- /dev/null\n+++ b/gcc/testsuite/g++.dg/reflect/ctad1.C\n@@ -0,0 +1,13 @@\n+// PR c++/124706\n+// { dg-do compile { target c++26 } }\n+// { dg-additional-options \"-freflection\" }\n+\n+template struct X;\n+template <> struct X {\n+ constexpr X(int) {}\n+};\n+X(int) -> X;\n+\n+static constexpr auto template_info = ^^X;\n+\n+[:template_info:] y{ 13 };\ndiff --git a/gcc/testsuite/g++.dg/reflect/ctad2.C b/gcc/testsuite/g++.dg/reflect/ctad2.C\nnew file mode 100644\nindex 00000000000..21f07a419b9\n--- /dev/null\n+++ b/gcc/testsuite/g++.dg/reflect/ctad2.C\n@@ -0,0 +1,24 @@\n+// PR c++/124706\n+// { dg-do compile { target c++26 } }\n+// { dg-additional-options \"-freflection\" }\n+\n+template \n+struct A\n+{\n+ A(T);\n+};\n+[:^^A:] a(42);\n+typename [:^^A:] a2(42);\n+\n+template struct B { T x; };\n+[:^^B:] b{0};\n+typename [:^^B:] b2{0};\n+\n+template\n+struct X { X(U) {} };\n+\n+template\n+using Y = X;\n+\n+[:^^Y:] y{1};\n+typename [:^^Y:] y2{1};\ndiff --git a/gcc/testsuite/g++.dg/reflect/error10.C b/gcc/testsuite/g++.dg/reflect/error10.C\nindex 891a643c1a0..1ac171c73cc 100644\n--- a/gcc/testsuite/g++.dg/reflect/error10.C\n+++ b/gcc/testsuite/g++.dg/reflect/error10.C\n@@ -39,8 +39,7 @@ template\n struct S {};\n \n void\n-fn5 (int, typename [: ^^S :] i) // { dg-error \"expected a reflection of a type|declared\" }\n-// { dg-message \"but .S. is a class template\" \"\" { target *-*-* } 39 }\n+fn5 (int, typename [: ^^S :] i) // { dg-error \"template placeholder not permitted in parameter\" }\n {\n }\n \n@@ -49,6 +48,6 @@ void bar ();\n \n void\n fn6 (int, typename [: ^^bar :] i) // { dg-error \"expected a reflection of a type|declared\" }\n-// { dg-message \"but .bar. is a function template\" \"\" { target *-*-* } 48 }\n+// { dg-message \"but .bar. is a function template\" \"\" { target *-*-* } 47 }\n {\n }\n","prefixes":[]}