From patchwork Wed Nov 16 20:59:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Wakely X-Patchwork-Id: 60716 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 8AF62396E439 for ; Wed, 16 Nov 2022 21:00:26 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 8AF62396E439 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1668632426; bh=npBLG/yyKAjzQfX9wXyYuVvOmF96j/uJSwtKHVtk5n4=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=bWFjIma2lea+ix5ZoTvBZN33GPIDrWOva55WCx4V22HhzHCmmGujIXVkD/kNkpHq7 jjDRLlfMZn1auqENPEJFQ9Ahz1zTNt7i+64cnrUbybaHLKPyGYsI7Ece2UUJL46S9C H/9wFeNecFQ2i5DFPKiLphSUv/SPX8PvQ76WbEwE= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 9D066396DC3C for ; Wed, 16 Nov 2022 20:59:56 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 9D066396DC3C Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-26-IoBgBTMyPbiMHozBjBRWGw-1; Wed, 16 Nov 2022 15:59:53 -0500 X-MC-Unique: IoBgBTMyPbiMHozBjBRWGw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1845A862FDF; Wed, 16 Nov 2022 20:59:53 +0000 (UTC) Received: from localhost (unknown [10.33.36.199]) by smtp.corp.redhat.com (Postfix) with ESMTP id D5BA9140EBF3; Wed, 16 Nov 2022 20:59:52 +0000 (UTC) To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: [committed] libstdc++: Disable std::format of _Float128 if std::to_chars is innaccurate Date: Wed, 16 Nov 2022 20:59:50 +0000 Message-Id: <20221116205950.1420057-1-jwakely@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-11.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Jonathan Wakely via Gcc-patches From: Jonathan Wakely Reply-To: Jonathan Wakely Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" Tested x86_64-linux. Pushed to trunk. -- >8 -- This restricts std::format support for _Float128 (and __float128) to targets where glibc provides __strfromf128 and so can give correct output. libstdc++-v3/ChangeLog: * include/std/format [__FLT128_DIG__] (_GLIBCXX_FORMAT_F128): Only support formatting _Float128 when glibc provides the functionality needed for accurate std::to_chars. --- libstdc++-v3/include/std/format | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format index 204a1710aca..fb29f7e7835 100644 --- a/libstdc++-v3/include/std/format +++ b/libstdc++-v3/include/std/format @@ -1235,13 +1235,13 @@ namespace __format using __float128_t = long double; # define _GLIBCXX_FORMAT_F128 1 -#elif __FLT128_DIG__ && defined(__GLIBC_PREREQ) // see floating_to_chars.cc +#elif __FLT128_DIG__ && defined(_GLIBCXX_HAVE_FLOAT128_MATH) // Format 128-bit floating-point types using _Float128. using __float128_t = _Float128; # define _GLIBCXX_FORMAT_F128 2 -# if __cplusplus == 202002L || !defined(_GLIBCXX_HAVE_FLOAT128_MATH) +# if __cplusplus == 202002L // These overloads exist in the library, but are not declared for C++20. // Make them available as std::__format::to_chars. to_chars_result