From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 531BA3858C53 for ; Wed, 4 Jan 2023 11:54:40 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 531BA3858C53 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1672833280; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=ZeUr5Ui97hzYqBck5EBYwWWbuPojGjh3oaSaILXx8V4=; b=in2MnVMC3JTrFb9+jnUtDU/tZ/ym3L811KPrBJvZgWyxGCvmOPZsQJMJ/tEdnCVI7JwVOq DMQSSoUJrUWpgUVneHUy1e3Q7EirABhq90uUYjuwL0sL3X42JOA7m2vWacA4C7uBQRuS1v NuWrbUo9tDB3i/6pvHn/FbiXl69wXDY= 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-91-PSQaLqFLO0yy4nK_53uAlw-1; Wed, 04 Jan 2023 06:54:38 -0500 X-MC-Unique: PSQaLqFLO0yy4nK_53uAlw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 60AB780D0E5; Wed, 4 Jan 2023 11:54:38 +0000 (UTC) Received: from localhost (unknown [10.33.36.242]) by smtp.corp.redhat.com (Postfix) with ESMTP id 27772C15BA0; Wed, 4 Jan 2023 11:54:38 +0000 (UTC) From: Jonathan Wakely To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: [committed] libstdc++: Fix std::array::data() to be a constant expression [PR108258] Date: Wed, 4 Jan 2023 11:54:37 +0000 Message-Id: <20230104115437.48991-1-jwakely@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Content-Transfer-Encoding: 8bit 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=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Tested x86_64-linux. Pushed to trunk. -- >8 -- When I refactored the __array_traits helper I broke this. libstdc++-v3/ChangeLog: PR libstdc++/108258 * include/std/array (__array_traits::operator T*()): Add constexpr. * testsuite/23_containers/array/element_access/constexpr_c++17.cc: Check std::array::data(). --- libstdc++-v3/include/std/array | 2 +- .../array/element_access/constexpr_c++17.cc | 19 ++++++++++++++++--- 2 files changed, 17 insertions(+), 4 deletions(-) diff --git a/libstdc++-v3/include/std/array b/libstdc++-v3/include/std/array index e26390e6f80..c50a201b032 100644 --- a/libstdc++-v3/include/std/array +++ b/libstdc++-v3/include/std/array @@ -69,7 +69,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // Conversion to a pointer produces a null pointer. __attribute__((__always_inline__)) - operator _Tp*() const noexcept { return nullptr; } + constexpr operator _Tp*() const noexcept { return nullptr; } }; using _Is_swappable = true_type; diff --git a/libstdc++-v3/testsuite/23_containers/array/element_access/constexpr_c++17.cc b/libstdc++-v3/testsuite/23_containers/array/element_access/constexpr_c++17.cc index b6878fd0c59..b92aa5c04e2 100644 --- a/libstdc++-v3/testsuite/23_containers/array/element_access/constexpr_c++17.cc +++ b/libstdc++-v3/testsuite/23_containers/array/element_access/constexpr_c++17.cc @@ -34,21 +34,34 @@ constexpr std::size_t test01() auto v2 = a.at(2); auto v3 = a.front(); auto v4 = a.back(); - return v1 + v2 + v3 + v4; + auto v5 = *a.data(); + return v1 + v2 + v3 + v4 + v5; } static_assert( test01() == (55 + 66 + 0 + 2) ); constexpr std::size_t test02() { - // array + // const array typedef std::array array_type; const array_type a = { { 0, 55, 66, 99, 4115, 2 } }; auto v1 = a[1]; auto v2 = a.at(2); auto v3 = a.front(); auto v4 = a.back(); - return v1 + v2 + v3 + v4; + auto v5 = *a.data(); + return v1 + v2 + v3 + v4 + v5; } static_assert( test02() == (55 + 66 + 0 + 2) ); + +constexpr bool test_zero() +{ + // zero-sized array (PR libstdc++/108258) + std::array a{}; + auto v4 = a.data(); + // The standard says this is unspecified, it's null for our implementation: + return a.data() == nullptr; +} + +static_assert( test_zero() ); -- 2.39.0