From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id D861F3896C1A; Wed, 7 Apr 2021 15:47:44 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org D861F3896C1A From: "msebor at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c/99950] Option -Wchar-subscripts leads to wrong fixes Date: Wed, 07 Apr 2021 15:47:44 +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: 11.0 X-Bugzilla-Keywords: diagnostic X-Bugzilla-Severity: enhancement X-Bugzilla-Who: msebor at gcc dot gnu.org X-Bugzilla-Status: NEW 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: everconfirmed cc see_also cf_reconfirmed_on bug_severity bug_status 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: Wed, 07 Apr 2021 15:47:45 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99950 Martin Sebor changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 CC| |msebor at gcc dot gnu.org See Also| |https://gcc.gnu.org/bugzill | |a/show_bug.cgi?id=3D78155 Last reconfirmed| |2021-04-07 Severity|normal |enhancement Status|UNCONFIRMED |NEW --- Comment #2 from Martin Sebor --- Adding a note after the warning suggesting to cast the argument to unsigned char would help. Enabling the warning also when the char argument is cast = to a wider type might also be worth considering. See also pr78155 for a related request to enable the warning for calls to the character classification built-ins. $ cat pr99950.c && gcc -O2 -S -Wall -Wchar-subscripts pr99950.c extern int a[255]; int f (char c) { return a[c]; // -Wchar-subscripts } int g (char c) { return a[(int)c]; // same bug, no warning } pr99950.c: In function =E2=80=98f=E2=80=99: pr99950.c:5:11: warning: array subscript has type =E2=80=98char=E2=80=99 [-= Wchar-subscripts] 5 | return a[c]; // -Wchar-subscripts | ^=