From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 56017385DC39; Fri, 18 Feb 2022 20:14:14 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 56017385DC39 From: "qinzhao at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/104550] bogus warning from -Wuninitialized + -ftrivial-auto-var-init=pattern Date: Fri, 18 Feb 2022 20:14:14 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: middle-end X-Bugzilla-Version: 12.0 X-Bugzilla-Keywords: diagnostic X-Bugzilla-Severity: normal X-Bugzilla-Who: qinzhao at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: qinzhao at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- 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, 18 Feb 2022 20:14:14 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104550 --- Comment #18 from qinzhao at gcc dot gnu.org --- One question here, for the following testing case: [opc@qinzhao-ol7u9 104550]$ cat t1.c struct vx_audio_level { int has_monitor_level : 1; }; void vx_set_monitor_level() { struct vx_audio_level info; __builtin_clear_padding (&info); } [opc@qinzhao-ol7u9 104550]$ sh t /home/opc/Install/latest/bin/gcc -O -Wuninitialized -Wall t1.c -S t1.c: In function =E2=80=98vx_set_monitor_level=E2=80=99: t1.c:7:2: warning: =E2=80=98info=E2=80=99 is used uninitialized [-Wuninitia= lized] 7 | __builtin_clear_padding (&info); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ t1.c:6:24: note: =E2=80=98info=E2=80=99 declared here 6 | struct vx_audio_level info; | ^~~~ We can see that the compiler emitted the exactly same warning as with -ftrivial-auto-var-init=3Dpattern.=20 my question is, is the "info" in __builtin_clear_padding(&info) a REAL use = of "info"? is it correct to report the uninitialized use message for it?=