From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 5C8113858012; Sat, 14 Aug 2021 19:27:35 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5C8113858012 From: "eggert at cs dot ucla.edu" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/101912] New: -Wmaybe-uninitialized false alarm in tzdb localtime.c Date: Sat, 14 Aug 2021 19:27:35 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 11.2.1 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: eggert at cs dot ucla.edu X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter target_milestone attachments.created Message-ID: 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: Sat, 14 Aug 2021 19:27:35 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101912 Bug ID: 101912 Summary: -Wmaybe-uninitialized false alarm in tzdb localtime.c Product: gcc Version: 11.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: eggert at cs dot ucla.edu Target Milestone: --- Created attachment 51303 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D51303&action=3Dedit -Wuninitialized false alarm This is a simplified version of a problem I found while compiling tzdb's localtime.c with gcc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1) on x86-64. Compile the attached program w.i with: gcc -Wmaybe-uninitialized -O2 -S w.i The output is: w.i: In function =E2=80=98tzloadbody=E2=80=99: w.i:17:27: warning: =E2=80=98prevcorr=E2=80=99 may be used uninitialized in= this function [-Wmaybe-uninitialized] 16 | : (corr =3D=3D prevcorr | ~~~~~~~~~~~~~~~~~ 17 | || corr =3D=3D prevcorr - 1))))) | ^~~~~~~~~~~~~~~~~~~~~~~~ This is a false alarm, since the underlined code is executed only when leap= cnt is nonzero, and leapcnt is set to a nonzero value only after prevcorr is initialized.=