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 AB8BC3856DC5 for ; Mon, 16 May 2022 17:06:28 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org AB8BC3856DC5 Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-671-RNqYrbwVP0uMXdOSZA1ZDw-1; Mon, 16 May 2022 13:06:24 -0400 X-MC-Unique: RNqYrbwVP0uMXdOSZA1ZDw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4EB793C16188 for ; Mon, 16 May 2022 17:06:23 +0000 (UTC) Received: from pdp-11.hsd1.ma.comcast.net (unknown [10.22.33.115]) by smtp.corp.redhat.com (Postfix) with ESMTP id 304787AD5; Mon, 16 May 2022 17:06:23 +0000 (UTC) From: Marek Polacek To: Jason Merrill , GCC Patches Subject: [PATCH] c++: suppress -Waddress warnings with *_cast [PR105569] Date: Mon, 16 May 2022 13:06:19 -0400 Message-Id: <20220516170619.358111-1-polacek@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true X-Spam-Status: No, score=-13.0 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, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham 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-List-Received-Date: Mon, 16 May 2022 17:06:30 -0000 dynamic_cast can legally return nullptr, so I don't think it's helpful for -Waddress to warn for if (dynamic_cast(&ref)) // ... More generally, it's likely not useful to warn for the artificial POINTER_PLUS_EXPRs created by build_base_path. Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? PR c++/105569 gcc/cp/ChangeLog: * class.cc (build_base_path): Suppress -Waddress warning. gcc/testsuite/ChangeLog: * g++.dg/warn/Waddress-9.C: New test. --- gcc/cp/class.cc | 2 ++ gcc/testsuite/g++.dg/warn/Waddress-9.C | 34 ++++++++++++++++++++++++++ 2 files changed, 36 insertions(+) create mode 100644 gcc/testsuite/g++.dg/warn/Waddress-9.C diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc index 3c195b35396..06167380423 100644 --- a/gcc/cp/class.cc +++ b/gcc/cp/class.cc @@ -518,6 +518,8 @@ build_base_path (enum tree_code code, expr = build1 (NOP_EXPR, ptr_target_type, expr); + suppress_warning (expr, OPT_Waddress); + indout: if (!want_pointer) { diff --git a/gcc/testsuite/g++.dg/warn/Waddress-9.C b/gcc/testsuite/g++.dg/warn/Waddress-9.C new file mode 100644 index 00000000000..2ec41949ccf --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Waddress-9.C @@ -0,0 +1,34 @@ +// PR c++/105569 +// { dg-do compile { target c++11 } } +// { dg-options -Waddress } + +class A {}; + +class B : public virtual A {}; + +class C : public A {}; + +int main() { + B* object = new B(); + B &ref = *object; + + // -Waddress warns here + bool b = nullptr == dynamic_cast(&ref); // { dg-bogus "-Waddress" } + bool b4 = nullptr == static_cast(&ref); // { dg-bogus "-Waddress" } + if (dynamic_cast(&ref)) // { dg-bogus "-Waddress" } + { + } + if (static_cast(&ref)) // { dg-bogus "-Waddress" } + { + } + + // -Waddress doesn't warn anymore + auto ptr = dynamic_cast(&ref); + bool b2 = ptr == nullptr; + + C* cobject = new C(); + C &cref = *cobject; + + // -Waddress also doesn't warn anymore + bool b3 = nullptr == dynamic_cast(&cref); +} base-commit: 682e587f1021241758f7dfe0b22651008622a312 -- 2.36.1