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 [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id A132D3858024 for ; Mon, 17 May 2021 14:02:18 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org A132D3858024 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-155-YuqX7KquPlib0XqgygQNsA-1; Mon, 17 May 2021 10:02:15 -0400 X-MC-Unique: YuqX7KquPlib0XqgygQNsA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5FD8C107ACCA; Mon, 17 May 2021 14:02:13 +0000 (UTC) Received: from localhost (unknown [10.33.36.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0C0A110027C4; Mon, 17 May 2021 14:02:12 +0000 (UTC) Date: Mon, 17 May 2021 15:02:12 +0100 From: Jonathan Wakely To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: [PATCH] libstdc++: Fix filesystem::path constraints for volatile [PR 100630] Message-ID: MIME-Version: 1.0 X-Clacks-Overhead: GNU Terry Pratchett X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/mixed; boundary="EX7QaZGd3Gogvd6c" Content-Disposition: inline X-Spam-Status: No, score=-14.1 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_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP, URI_HEX autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libstdc++@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++ mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 17 May 2021 14:02:29 -0000 --EX7QaZGd3Gogvd6c Content-Type: text/plain; charset=us-ascii Content-Disposition: inline The constraint check for filesystem::path construction uses decltype(__is_path_src(declval())) which mean it considers conversion from an rvalue. When Source is a volatile-qualified type it cannot use is_path_src(const Unknown&) because a const lvalue reference can only bind to a non-volatile rvalue. Since the relevant path members all have a const Source& parameter, the constraint should be defined in terms of declval(), not declval(). This avoids the problem of volatile-qualified rvalues, because we no longer use an rvalue at all. libstdc++-v3/ChangeLog: PR libstdc++/100630 * include/bits/fs_path.h (__is_constructible_from): Test construction from a const lvalue, not an rvalue. * include/experimental/bits/fs_path.h (__is_constructible_from): Likewise. * testsuite/27_io/filesystem/path/construct/100630.cc: New test. * testsuite/experimental/filesystem/path/construct/100630.cc: New test. Tested x86_64-linux, pushed to gcc-10 (this isn't needed for gcc-11 or trunk, but I also plan to backport it to gcc-9). --EX7QaZGd3Gogvd6c Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="patch.txt" commit 4cd69a5a0dd31bc6fdef1bbabc8d6d1416014ea1 Author: Jonathan Wakely Date: Mon May 17 11:54:06 2021 libstdc++: Fix filesystem::path constraints for volatile [PR 100630] The constraint check for filesystem::path construction uses decltype(__is_path_src(declval())) which mean it considers conversion from an rvalue. When Source is a volatile-qualified type it cannot use is_path_src(const Unknown&) because a const lvalue reference can only bind to a non-volatile rvalue. Since the relevant path members all have a const Source& parameter, the constraint should be defined in terms of declval(), not declval(). This avoids the problem of volatile-qualified rvalues, because we no longer use an rvalue at all. libstdc++-v3/ChangeLog: PR libstdc++/100630 * include/bits/fs_path.h (__is_constructible_from): Test construction from a const lvalue, not an rvalue. * include/experimental/bits/fs_path.h (__is_constructible_from): Likewise. * testsuite/27_io/filesystem/path/construct/100630.cc: New test. * testsuite/experimental/filesystem/path/construct/100630.cc: New test. diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h index 3d341916db5..6e0a85417cc 100644 --- a/libstdc++-v3/include/bits/fs_path.h +++ b/libstdc++-v3/include/bits/fs_path.h @@ -116,7 +116,7 @@ namespace __detail template struct __constructible_from<_Source, void> - : decltype(__is_path_src(std::declval<_Source>(), 0)) + : decltype(__is_path_src(std::declval(), 0)) { }; template diff --git a/libstdc++-v3/include/experimental/bits/fs_path.h b/libstdc++-v3/include/experimental/bits/fs_path.h index c5fc3beed1f..0a8f4eee0a1 100644 --- a/libstdc++-v3/include/experimental/bits/fs_path.h +++ b/libstdc++-v3/include/experimental/bits/fs_path.h @@ -124,7 +124,7 @@ namespace __detail template struct __constructible_from<_Source, void> - : decltype(__is_path_src(std::declval<_Source>(), 0)) + : decltype(__is_path_src(std::declval(), 0)) { }; template + +void f(bool) { } +void f(const std::filesystem::path&) { } + +void +test_100630() +{ + volatile bool b = true; + f(b); +} diff --git a/libstdc++-v3/testsuite/experimental/filesystem/path/construct/100630.cc b/libstdc++-v3/testsuite/experimental/filesystem/path/construct/100630.cc new file mode 100644 index 00000000000..b2428ff74cf --- /dev/null +++ b/libstdc++-v3/testsuite/experimental/filesystem/path/construct/100630.cc @@ -0,0 +1,14 @@ +// { dg-do compile { target c++11 } } +// { dg-require-filesystem-ts "" } + +#include + +void f(bool) { } +void f(const std::experimental::filesystem::path&) { } + +void +test_100630() +{ + volatile bool b = true; + f(b); +} --EX7QaZGd3Gogvd6c--