From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 2DD6C387089C; Fri, 19 Mar 2021 23:30:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 2DD6C387089C From: "cvs-commit at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/99362] [10 Regression] invalid unused result Date: Fri, 19 Mar 2021 23:30:15 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c++ X-Bugzilla-Version: 10.2.1 X-Bugzilla-Keywords: diagnostic X-Bugzilla-Severity: normal X-Bugzilla-Who: cvs-commit at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: jakub at gcc dot gnu.org X-Bugzilla-Target-Milestone: 10.3 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Mar 2021 23:30:16 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99362 --- Comment #8 from CVS Commits --- The releases/gcc-10 branch has been updated by Jakub Jelinek : https://gcc.gnu.org/g:01edf2031461b558f630afea382a813e41b631e6 commit r10-9481-g01edf2031461b558f630afea382a813e41b631e6 Author: Jakub Jelinek Date: Thu Mar 4 16:04:48 2021 +0100 c++: Fix up [[nodiscard]] on ctors on targetm.cxx.cdtor_returns_this targets [PR99362] In the P1771R1 changes JeanHeyd reverted part of Alex' PR88146 fix, but that seems to be incorrect to me. Where P1771R1 suggests warnings for [[nodiscard]] on constructors is handled in a different place - in particular the TARGET_EXPR handling of convert_to_void. When we have CALL_EXPR of a ctor, on most arches that call has void return type and so returns early, and on arm where the ctor returns the this pointer it is undesirable to warn as it warns about all ctor calls, not just the ones where it should warn. The P1771R1 changes added a test for this, but as it was given *.c extension rather than *.C, the test was never run and so this didn't get spotted immediately. The test also had a bug, (?n) can't be used in dg-warning/dg-error because those are implemented by prepending some regexp before the user provided one and (?n) must come at the start of the regexp. Furthermore, while -ftrack-macro-expansion=3D0 is useful in one nodiscard test which uses macros, I don't see how it would be relevant to all the other cpp2a/nodiscard* tests which don't use any macros. 2021-03-04 Jakub Jelinek PR c++/88146 PR c++/99362 gcc/cp/ * cvt.c (convert_to_void): Revert 2019-10-17 changes. Clarify comment. gcc/testsuite/ * g++.dg/cpp2a/nodiscard-constructor.c: Renamed to ... * g++.dg/cpp2a/nodiscard-constructor1.C: ... this. Remove -ftrack-macro-expansion=3D0 from dg-options. Don't use (?n) in dg-warning regexps, instead replace .* with \[^\n\r]*. * g++.dg/cpp2a/nodiscard-constructor2.C: New test. * g++.dg/cpp2a/nodiscard-reason-only-one.C: Remove -ftrack-macro-expansion=3D0 from dg-options. * g++.dg/cpp2a/nodiscard-reason-nonstring.C: Likewise. * g++.dg/cpp2a/nodiscard-once.C: Likewise. (cherry picked from commit c9816196328a4f4b927f08cf2f66cf255849da0b)=