{"id":2224715,"url":"http://patchwork.ozlabs.org/api/patches/2224715/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/patch/20260417211713.450546-1-jwakely@redhat.com/","project":{"id":17,"url":"http://patchwork.ozlabs.org/api/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,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260417211713.450546-1-jwakely@redhat.com>","list_archive_url":null,"date":"2026-04-17T21:16:31","name":"[wwwdocs] Document change to -std=gnu++20 and non-experimental C++20 support","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"b384d6769fbee64fe28aecf918a0207d488c5288","submitter":{"id":48004,"url":"http://patchwork.ozlabs.org/api/people/48004/?format=json","name":"Jonathan Wakely","email":"jwakely@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/gcc/patch/20260417211713.450546-1-jwakely@redhat.com/mbox/","series":[{"id":500405,"url":"http://patchwork.ozlabs.org/api/series/500405/?format=json","web_url":"http://patchwork.ozlabs.org/project/gcc/list/?series=500405","date":"2026-04-17T21:16:31","name":"[wwwdocs] Document change to -std=gnu++20 and non-experimental C++20 support","version":1,"mbox":"http://patchwork.ozlabs.org/series/500405/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2224715/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2224715/checks/","tags":{},"related":[],"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=T57XarFr;\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=1776460641;\n h=from:from:reply-to:subject:subject:date:date:message-id:message-id:\n to:to:cc:cc:mime-version:mime-version:content-type:content-type:\n content-transfer-encoding:content-transfer-encoding;\n bh=uHZ0ZpnN7qeZtZSurYjJCUgHW4tXv+PZA+9TVTvYzJw=;\n b=T57XarFrJ3hLqGr+YUdAq4Aota2RQfYKUM88QkYoRyiKr/KVJv8xC9BptQIf5VJr64z6EO\n izrm/dT5kWqJoVtt4cf2qoQx4/TPMDpCSTXyz5M2Y+UDiFx/F715dpG8hucB1XRJpyPUTl\n pVpVY91aXRI5UHCtca51udM33SnzRBA=","X-MC-Unique":"4w9GBAJIN8y3IDXkWHHEFQ-1","X-Mimecast-MFC-AGG-ID":"4w9GBAJIN8y3IDXkWHHEFQ_1776460637","From":"Jonathan Wakely ","To":"gcc-patches@gcc.gnu.org,\n\tlibstdc++@gcc.gnu.org","Cc":"Jason Merrill ","Subject":"[wwwdocs] Document change to -std=gnu++20 and non-experimental C++20\n support","Date":"Fri, 17 Apr 2026 22:16:31 +0100","Message-ID":"<20260417211713.450546-1-jwakely@redhat.com>","MIME-Version":"1.0","X-Scanned-By":"MIMEDefang 3.0 on 10.30.177.12","X-Mimecast-Spam-Score":"0","X-Mimecast-MFC-PROC-ID":"CTW4bMYeibmB90Eidg7g9DwJU2jnE-m7Kf35hND60Lg_1776460637","X-Mimecast-Originator":"redhat.com","Content-Type":"text/plain","Content-Transfer-Encoding":"8bit","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":"Does this look OK for wwwdocs?\n\nThere are other libstdc++ changes that should be added to this page, and\nthe porting_to.html page needs work, but this is the main thing.\n\n---\n htdocs/gcc-16/changes.html | 21 +++++++++++++++++----\n 1 file changed, 17 insertions(+), 4 deletions(-)","diff":"diff --git a/htdocs/gcc-16/changes.html b/htdocs/gcc-16/changes.html\nindex fb0719d5..56c63e99 100644\n--- a/htdocs/gcc-16/changes.html\n+++ b/htdocs/gcc-16/changes.html\n@@ -204,6 +204,16 @@ for general information.

\n

C++

\n \n
    \n+
  • C++20 by default: GCC 16 changes the default language version\n+ for C++ compilation from\n+ -std=gnu++17\n+ to\n+ -std=gnu++20.\n+ If your code relies on older versions of the C++ standard, you will need to\n+ either add\n+ -std=\n+ to your build flags, or port your code; see the porting notes.\n+
    • \n
  • Several C++26 features have been implemented:\n
      \n
    • P2996R13, Reflection\n@@ -295,8 +305,11 @@ struct Affected : E\n C++17 mode.\n
      • \n \n-
    • Improved experimental support for C++20, including:\n+
    • Improved support for C++20, including:\n
        \n+
      • \n+ The C++20 implementation is no longer experimental.\n+
        • \n
      • \n Working std::chrono::current_zone() on Windows\n (thanks to Björn Schäpers).\n@@ -331,9 +344,9 @@ struct Affected : E\n Representation of some range adaptors in <ranges>.\n
        • \n
      \n- This list is not necessarily complete. As with all experimental support,\n- programs using C++20 components should assume that those components\n- are not compatible between different major releases.\n+ This list is not necessarily complete. As C++20 support was experimental\n+ before GCC 16, programs using C++20 components should assume that those\n+ components are not compatible with older releases.\n
      • \n
    • Improved experimental support for C++23, including:\n
        \n","prefixes":["wwwdocs"]}