Cover Letter Detail
Show a cover letter.
GET /api/covers/2226647/?format=api
{ "id": 2226647, "url": "http://patchwork.ozlabs.org/api/covers/2226647/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/cover/bmm.hhunfc5mlg.gcc.gcc-TEST.peppe.36.1.0@forge-stage.sourceware.org/", "project": { "id": 17, "url": "http://patchwork.ozlabs.org/api/projects/17/?format=api", "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, "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<bmm.hhunfc5mlg.gcc.gcc-TEST.peppe.36.1.0@forge-stage.sourceware.org>", "list_archive_url": null, "date": "2026-04-22T17:47:27", "name": "[v1,0/1] WIP: libstdc++: constrain std::atomic's default constructor", "submitter": { "id": 93222, "url": "http://patchwork.ozlabs.org/api/people/93222/?format=api", "name": "peppe via Sourceware Forge", "email": "forge-bot+peppe@forge-stage.sourceware.org" }, "mbox": "http://patchwork.ozlabs.org/project/gcc/cover/bmm.hhunfc5mlg.gcc.gcc-TEST.peppe.36.1.0@forge-stage.sourceware.org/mbox/", "series": [ { "id": 501056, "url": "http://patchwork.ozlabs.org/api/series/501056/?format=api", "web_url": "http://patchwork.ozlabs.org/project/gcc/list/?series=501056", "date": "2026-04-22T17:47:28", "name": "WIP: libstdc++: constrain std::atomic's default constructor", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/501056/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2226647/comments/", "headers": { "Return-Path": "<gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org>", "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 spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org\n (client-ip=2620:52:6:3111::32; helo=vm01.sourceware.org;\n envelope-from=gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org;\n receiver=patchwork.ozlabs.org)", "sourceware.org; dmarc=none (p=none dis=none)\n header.from=forge-stage.sourceware.org", "sourceware.org;\n spf=pass smtp.mailfrom=forge-stage.sourceware.org", "server2.sourceware.org;\n arc=none smtp.remote-ip=38.145.34.39" ], "Received": [ "from vm01.sourceware.org (vm01.sourceware.org\n [IPv6:2620:52:6:3111::32])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g16G14Sxdz1y2d\n\tfor <incoming@patchwork.ozlabs.org>; Thu, 23 Apr 2026 03:50:49 +1000 (AEST)", "from vm01.sourceware.org (localhost [127.0.0.1])\n\tby sourceware.org (Postfix) with ESMTP id C03014B920FA\n\tfor <incoming@patchwork.ozlabs.org>; Wed, 22 Apr 2026 17:50:47 +0000 (GMT)", "from forge-stage.sourceware.org (vm08.sourceware.org [38.145.34.39])\n by sourceware.org (Postfix) with ESMTPS id 1E9854B9DB63\n for <gcc-patches@gcc.gnu.org>; Wed, 22 Apr 2026 17:48:22 +0000 (GMT)", "from forge-stage.sourceware.org (localhost [IPv6:::1])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange x25519 server-signature ECDSA (prime256v1) server-digest SHA256)\n (No client certificate requested)\n by forge-stage.sourceware.org (Postfix) with ESMTPS id E294042BF4\n for <gcc-patches@gcc.gnu.org>; Wed, 22 Apr 2026 17:48:21 +0000 (UTC)" ], "DKIM-Filter": [ "OpenDKIM Filter v2.11.0 sourceware.org C03014B920FA", "OpenDKIM Filter v2.11.0 sourceware.org 1E9854B9DB63" ], "DMARC-Filter": "OpenDMARC Filter v1.4.2 sourceware.org 1E9854B9DB63", "ARC-Filter": "OpenARC Filter v1.0.0 sourceware.org 1E9854B9DB63", "ARC-Seal": "i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1776880102; cv=none;\n b=J56dODkNy2HqD4sPW9xJnuI3HBxGrqnfhzjHW1/4N5gzGzQmOuMji3Sabwsk6Oaww/mOzRd6DwKpBn8w4TroJfqVIBmS60AKGJyMA+DWnWjmxlzgRKVuF9dUN1LQGebl2Lp+LCuzFKQ8lAnF+tXA1qVgRu2A5orX2zxQDhYASy4=", "ARC-Message-Signature": "i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1776880102; c=relaxed/simple;\n bh=gPiTd7DUxrvXZDNrqVoCmBYbDojEJVnoHUe8IlB5+xw=;\n h=From:Date:Subject:To:Message-ID;\n b=ICdeG/VvoaiMsuXzGF8a1Dtoe5aZR9S10e9/0FkZj+H4TCT4rY+lCpdg4Hx/gA2feAYfeLghn+VqvDeTNoaXsSUFrRqEuvtvrSq6DkTkp9E7VX8h5OT5Ohs0mwRKMAM+3K7VpKnHOuhdkUT0KxwU+ostwCKBsivfTh+iJpGpyxk=", "ARC-Authentication-Results": "i=1; server2.sourceware.org", "From": "peppe via Sourceware Forge <forge-bot+peppe@forge-stage.sourceware.org>", "Date": "Wed, 22 Apr 2026 17:47:27 +0000", "Subject": "[PATCH v1 0/1] WIP: libstdc++: constrain std::atomic's default\n constructor", "To": "gcc-patches mailing list <gcc-patches@gcc.gnu.org>", "Message-ID": "\n <bmm.hhunfc5mlg.gcc.gcc-TEST.peppe.36.1.0@forge-stage.sourceware.org>", "X-Mailer": "batrachomyomachia", "X-Requested-Reviewer": "redi", "X-Pull-Request-Organization": "gcc", "X-Pull-Request-Repository": "gcc-TEST", "X-Pull-Request": "https://forge.sourceware.org/gcc/gcc-TEST/pulls/36", "X-BeenThere": "gcc-patches@gcc.gnu.org", "X-Mailman-Version": "2.1.30", "Precedence": "list", "List-Id": "Gcc-patches mailing list <gcc-patches.gcc.gnu.org>", "List-Unsubscribe": "<https://gcc.gnu.org/mailman/options/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=unsubscribe>", "List-Archive": "<https://gcc.gnu.org/pipermail/gcc-patches/>", "List-Post": "<mailto:gcc-patches@gcc.gnu.org>", "List-Help": "<mailto:gcc-patches-request@gcc.gnu.org?subject=help>", "List-Subscribe": "<https://gcc.gnu.org/mailman/listinfo/gcc-patches>,\n <mailto:gcc-patches-request@gcc.gnu.org?subject=subscribe>", "Reply-To": "gcc-patches mailing list <gcc-patches@gcc.gnu.org>,\n peppe@noreply.localhost", "Errors-To": "gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org" }, "content": "Hi gcc-patches mailing list,\npeppe via Sourceware Forge <forge-bot+peppe@forge-stage.sourceware.org> has requested that the following forgejo pull request\nbe published on the mailing list.\n\nCreated on: 2025-03-06 10:32:34+00:00\nLatest update: 2025-08-13 03:36:59+00:00\nChanges: 0 changed files, 0 additions, 0 deletions\nHead revision: peppe/gcc-TEST ref refs/pull/36/head commit 50befa32f7cc696850607d9c09b81a4de529597a\nBase revision: gcc/gcc-TEST ref trunk commit e6e7b477bbdbfb3fee6b44087a59f94fd1e2c7a3 r15-7897-ge6e7b477bbdbfb\nMerge base: e6e7b477bbdbfb3fee6b44087a59f94fd1e2c7a3\nFull diff url: https://forge.sourceware.org/gcc/gcc-TEST/pulls/36.diff\nDiscussion: https://forge.sourceware.org/gcc/gcc-TEST/pulls/36\nRequested Reviewers: redi\n\nThis commit implements the proposed resolution to LWG4169, which is\nto constrain std::atomic<T>'s default constructor based on whether\nT itself is default constructible.\n\nAt the moment, std::atomic<T>'s primary template in libstdc++ has a\ndefaulted default constructor. Value-initialization of the T member\n(since C++20 / P0883R2) is done via a NSDMI (= T()).\n\nGCC already considers the defaulted constructor constrained/deleted,\nhowever this behavior is non-standard (see the discussion in PR116769):\nthe presence of a NSDMI should not make the constructor unavailable to\noverload resolution/deleted ([class.default.ctor]/2.5 does not apply).\nWhen using libstdc++ on Clang, this causes build issues as the\nconstructor is *not* deleted there -- the interpretation of\n[class.default.ctor]/4 seems to match Clang's behavior.\n\nTherefore, although there would be \"nothing to do\" with GCC+libstdc++,\nthis commit changes the code as to stop relying on the GCC language\nextension. std::atomic's defaulted default constructor is changed to be\na non-defaulted one, with a constraint added as per LWG4169;\nvalue-initialization of the data member is moved from the NSDMI to the\nmember init list. The new signature matches the one in the Standard as\nper [atomics.types.operations]/1.\n\nA test that explictly instantiated std::atomic with a non-default\nconstructible type needed to be amended. Such an instantiation would\ninstantiate all member functions (as per [temp.explicit]/9), including\nthe default constructor, which now triggers a hard error when built in\npre-C++20 modes.\n\nIn its place I've instead added a couple of static_asserts checking that\nstd::atomic is default constructible even with a non-default\nconstructible T (in pre-C++20 modes), or is not default constructible\nat all (since C++20).\n\n```\nlibstdc++-v3/ChangeLog:\n\n\t* include/std/atomic (atomic): Turn the defaulted default\n\tconstructor in a non-defaulted one, constraining it as per\n\tLWG4169; remove the NSDMI for the _M_i member.\n\t(_GLIBCXX20_INIT): Drop the macro, as it is not needed any more.\n\t* testsuite/29_atomics/atomic/69301.cc: Restrict the explicit\n\tclass instantation only to C++ >= 20 modes; it would otherwise\n\tcause a hard error. Add a new test.\n\t* testsuite/29_atomics/atomic/cons/value_init.cc: Add a new test.\n```\n\n\nChanged files:\n- A: libstdc++-v3/testsuite/29_atomics/atomic/cons/trivial.cc\n- M: libstdc++-v3/include/bits/version.def\n- M: libstdc++-v3/include/bits/version.h\n- M: libstdc++-v3/include/std/atomic\n- M: libstdc++-v3/testsuite/29_atomics/atomic/69301.cc\n\n\nGiuseppe D'Angelo (1):\n libstdc++: constrain std::atomic's default constructor\n\n libstdc++-v3/include/bits/version.def | 1 +\n libstdc++-v3/include/bits/version.h | 2 +-\n libstdc++-v3/include/std/atomic | 22 +++++-----\n .../testsuite/29_atomics/atomic/69301.cc | 2 +\n .../29_atomics/atomic/cons/trivial.cc | 41 +++++++++++++++++++\n 5 files changed, 57 insertions(+), 11 deletions(-)\n create mode 100644 libstdc++-v3/testsuite/29_atomics/atomic/cons/trivial.cc" }