[{"id":3684281,"web_url":"http://patchwork.ozlabs.org/comment/3684281/","msgid":"<29128558-8827-41b8-8526-0a9a5a565323@redhat.com>","list_archive_url":null,"date":"2026-04-29T21:25:01","subject":"Re: [PATCH gcc-wwwdocs] gcc-16: document some notable C++ changes","submitter":{"id":4337,"url":"http://patchwork.ozlabs.org/api/people/4337/","name":"Jason Merrill","email":"jason@redhat.com"},"content":"On 4/29/26 2:25 PM, Patrick Palka wrote:\n> OK to push?\n\nLooks good.\n\n> -- >8 --\n> ---\n>   htdocs/gcc-16/changes.html | 28 ++++++++++++++++++++++++++++\n>   1 file changed, 28 insertions(+)\n> \n> diff --git a/htdocs/gcc-16/changes.html b/htdocs/gcc-16/changes.html\n> index cab3bca4..fc100056 100644\n> --- a/htdocs/gcc-16/changes.html\n> +++ b/htdocs/gcc-16/changes.html\n> @@ -286,6 +286,34 @@ for general information.</p>\n>       <!-- commit b76d9f7c1f2e14a576e2e548b0d454a1f16c7fde\n>   \t c++: UX improvements for close matches in print_candidates -->\n>     </li>\n> +  <li>Experimental C++20 modules support\n> +    <ul>\n> +      <li>\n> +        New command line option <code>--compile-std-module</code> that\n> +        conveniently builds the <code>&lt;bits/stdc++.h&gt;</code> header unit\n> +        and the <code>std</code> and <code>std.compat</code> modules before\n> +        compiling any source files explicitly specified on the command line.\n> +      </li>\n> +      <li>\n> +        Whenever the <code>&lt;bits/stdc++.h&gt;</code> header unit has been\n> +        built, GCC now transparently translates an <code>#include</code> of\n> +        any importable standard library header into an <code>import</code> of\n> +        <code>&lt;bits/stdc++.h&gt;</code>.\n> +      </li>\n> +      <li>\n> +      </li>\n> +      <li>\n> +        Many reported bugs have been fixed, thanks to Nathaniel Shead.\n> +      </li>\n> +    </ul>\n> +  </li>\n> +  <li>\n> +    Constraint failure diagnostics for standard library type traits\n> +    such as <code>is_constructible_v</code> and <code>is_invocable_v</code>\n> +    are improved to further elaborate why the trait is <code>false</code>\n> +    instead of just reporting <code>expression is_foo_v&lt;...&gt; evaluates to\n> +    false</code>, thanks to Nathaniel Shead.\n> +  </li>\n>   </ul>\n>   \n>   <h4 id=\"libstdcxx\">Runtime Library (libstdc++)</h4>","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\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=KK4hiirE;\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; helo=vm01.sourceware.org;\n envelope-from=gcc-patches-bounces~incoming=patchwork.ozlabs.org@gcc.gnu.org;\n receiver=patchwork.ozlabs.org)","sourceware.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=KK4hiirE","sourceware.org; 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