From patchwork Tue Jan 18 20:44:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Wakely X-Patchwork-Id: 50187 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 0EA1C3858032 for ; Tue, 18 Jan 2022 20:45:29 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 0EA1C3858032 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1642538729; bh=fmhPhBDMEvNB93CfH+R6K8rVlXo+T+5HN+SwLc/oFBw=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=ViO/v+185uYBHaV4U64KGqYwDbjlnMpBoeCNsXRikbEcjzpD3xtSb4PGuzxCE1jES U7O9uQULxhk3PTifQ2iU1qXf/aUOZWcwMFqtTPDYDDhCX0uaR5fCq7tE6BMWhn7U65 xtOucIERvU+1Dpl3zULL39PG3xFYjUB70d3B3xLY= 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 [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id F3C6C3858035 for ; Tue, 18 Jan 2022 20:44:17 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org F3C6C3858035 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-439-coC6RlbPM0OChc_am-m86Q-1; Tue, 18 Jan 2022 15:44:09 -0500 X-MC-Unique: coC6RlbPM0OChc_am-m86Q-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0DEDE6123D; Tue, 18 Jan 2022 20:44:08 +0000 (UTC) Received: from localhost (unknown [10.33.37.93]) by smtp.corp.redhat.com (Postfix) with ESMTP id B0B7612E0D; Tue, 18 Jan 2022 20:44:07 +0000 (UTC) To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: [committed] libstdc++: Limit new basic_string(nullptr_t) constructor to C++23 [PR104099] Date: Tue, 18 Jan 2022 20:44:06 +0000 Message-Id: <20220118204406.3842572-1-jwakely@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-15.0 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_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=unavailable autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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 powerpc64le-linux, pushed to trunk. The new deleted constructors added by P2166R1 are a breaking change, making previously valid code ill-formed in C++23. As a result, they should only be defined for C++23 and not for C++11 and up. libstdc++-v3/ChangeLog: PR libstdc++/104099 * include/bits/basic_string.h (basic_string(nullptr_t)): Only define for C++23. (operator=(nullptr_t)): Likewise. * include/bits/cow_string.h: Likewise. * include/std/string_view (basic_string_view(nullptr_t)): Likewise. * testsuite/21_strings/basic_string/cons/char/nullptr.cc: Adjust expected error. Add examples that become ill-formed in C++23. * testsuite/21_strings/basic_string_view/cons/char/nonnull.cc: Adjust expected errors. * testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc: Likewise. --- libstdc++-v3/include/bits/basic_string.h | 4 ++- libstdc++-v3/include/bits/cow_string.h | 4 ++- libstdc++-v3/include/std/string_view | 3 ++- .../basic_string/cons/char/nullptr.cc | 26 ++++++++++++++++++- .../basic_string_view/cons/char/nonnull.cc | 3 ++- .../basic_string_view/cons/wchar_t/nonnull.cc | 3 ++- 6 files changed, 37 insertions(+), 6 deletions(-) diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h index a91ba5114b1..fc6a303a957 100644 --- a/libstdc++-v3/include/bits/basic_string.h +++ b/libstdc++-v3/include/bits/basic_string.h @@ -728,10 +728,12 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 else _M_construct(__str.begin(), __str.end(), std::forward_iterator_tag()); } +#endif // C++11 +#if __cplusplus >= 202100L basic_string(nullptr_t) = delete; basic_string& operator=(nullptr_t) = delete; -#endif // C++11 +#endif // C++23 /** * @brief Construct string as copy of a range. diff --git a/libstdc++-v3/include/bits/cow_string.h b/libstdc++-v3/include/bits/cow_string.h index 84aab2f33c6..a49a5b04f2f 100644 --- a/libstdc++-v3/include/bits/cow_string.h +++ b/libstdc++-v3/include/bits/cow_string.h @@ -665,10 +665,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION else _M_dataplus._M_p = _S_construct(__str.begin(), __str.end(), __a); } +#endif // C++11 +#if __cplusplus >= 202100L basic_string(nullptr_t) = delete; basic_string& operator=(nullptr_t) = delete; -#endif // C++11 +#endif // C++23 /** * @brief Construct string as copy of a range. diff --git a/libstdc++-v3/include/std/string_view b/libstdc++-v3/include/std/string_view index 99080e9eccd..bccf4d1847f 100644 --- a/libstdc++-v3/include/std/string_view +++ b/libstdc++-v3/include/std/string_view @@ -167,10 +167,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r))) : _M_len(ranges::size(__r)), _M_str(ranges::data(__r)) { } + + basic_string_view(nullptr_t) = delete; #endif // C++23 #endif // C++20 - basic_string_view(nullptr_t) = delete; constexpr basic_string_view& operator=(const basic_string_view&) noexcept = default; diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nullptr.cc b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nullptr.cc index fdb24aeeb89..a69fa614ba3 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nullptr.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string/cons/char/nullptr.cc @@ -1,4 +1,28 @@ // { dg-do compile { target c++11 } } #include -std::string s = nullptr; // { dg-error "deleted" "P2166R1" } +std::string s = nullptr; // { dg-error "deleted" "P2166R1" { target c++23 } } + +struct S +{ + operator const char*() const { return ""; } + operator std::nullptr_t() const { return {}; } +}; + +std::string s2{ S{} }; // { dg-error "deleted" "PR 104099" { target c++23 } } + +#if __cpp_concepts +struct J +{ + // In C++20 this selects basic_string(const char*), + // in C++23 it's ambiguous due to basic_string(nullptr_t). + template + requires (!std::is_same_v, T>) + && (!std::is_same_v) + && (!std::is_same_v) + && (!std::is_same_v) + operator T() const { return {}; } +}; + +std::string s3{ J{} }; // { dg-error "ambiguous" "PR 104099" { target c++23 } } +#endif diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc index 00bb8e414b8..2e43788e4f5 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/nonnull.cc @@ -25,5 +25,6 @@ test01() { std::string_view s((const char*)nullptr); // { dg-warning "\\\[-Wnonnull" } std::string_view t((char*)nullptr); // { dg-warning "\\\[-Wnonnull" } - std::string_view u(nullptr); // { dg-error "deleted" } + std::string_view u(nullptr); // { dg-warning "\\\[-Wnonnull" "" { target c++20_down } } +// { dg-error "deleted" "P2166R1" { target c++23 } 0 } } diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc index 685d48c3fd7..a146d383324 100644 --- a/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc +++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/nonnull.cc @@ -25,5 +25,6 @@ test01() { std::wstring_view s((const wchar_t*)nullptr); // { dg-warning "\\\[-Wnonnull" } std::wstring_view t((wchar_t*)nullptr); // { dg-warning "\\\[-Wnonnull" } - std::wstring_view u(nullptr); // { dg-error "deleted" } + std::wstring_view u(nullptr); // { dg-warning "\\\[-Wnonnull" "" { target c++20_down } } +// { dg-error "deleted" "P2166R1" { target c++23 } 0 } }