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From: "jasonwucj at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c/7652] -Wswitch-break : Warn if a switch case falls through Date: Sun, 23 Jun 2013 12:21:00 -0000 [thread overview] Message-ID: <bug-7652-4-OcPcQ2vBxk@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-7652-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=7652 Chung-Ju Wu <jasonwucj at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jasonwucj at gmail dot com --- Comment #19 from Chung-Ju Wu <jasonwucj at gmail dot com> --- (In reply to David Binderman from comment #17) > (In reply to Daniel Marjamäki from comment #7) > > In my experience this type of check is really noisy if there is a warning > > for every fall through. > > > > I recommend that the warning is written only if the fall through cause > > redundant or bad behaviour. such as: > > > > switch (foo) { > > case 1: x = y; // <- redundant assignment > > case 2: x = z; > > }; > > I'd be happy with gcc warning for this kind of problem. > > This specific case should be easier to catch than the > general case. I believe such redundant assignment will be optimized out. $ gcc --version gcc (20130621) 4.9.0 20130621 (experimental) Copyright (C) 2013 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ gcc -O2 -S pr7652.c [pr7652.c] 1 2 extern int a; 3 extern int b; 4 extern int c; 5 6 int 7 main(int argc, char **argv) 8 { 9 int x; 10 11 switch (argc) 12 { 13 case 1: 14 x = a; 15 case 7: 16 x = b; 17 break; 18 default: 19 x = c; 20 break; 21 } 22 23 return x; 24 } [pr7652.s] 1 .file "pr7652.c" 2 .section .text.startup,"ax",@progbits 3 .p2align 4,,15 4 .globl main 5 .type main, @function 6 main: 7 .LFB0: 8 .cfi_startproc 9 movl 4(%esp), %eax 10 cmpl $1, %eax 11 je .L3 12 cmpl $7, %eax 13 je .L3 14 movl c, %eax 15 ret 16 .L3: 17 movl b, %eax 18 ret 19 .cfi_endproc 20 .LFE0: 21 .size main, .-main 22 .ident "GCC: (20130621) 4.9.0 20130621 (experimental)" 23 .section .note.GNU-stack,"",@progbits Apparently it is dead code. IMHO, it may not be a good idea to have compiler issue a warning everytime when compiler identifies dead code statements. >From gcc-bugs-return-424895-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Sun Jun 23 12:25:40 2013 Return-Path: <gcc-bugs-return-424895-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org> Delivered-To: listarch-gcc-bugs@gcc.gnu.org Received: (qmail 20466 invoked by alias); 23 Jun 2013 12:25:40 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: <gcc-bugs.gcc.gnu.org> List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/> List-Post: <mailto:gcc-bugs@gcc.gnu.org> List-Help: <mailto:gcc-bugs-help@gcc.gnu.org> Sender: gcc-bugs-owner@gcc.gnu.org Delivered-To: mailing list gcc-bugs@gcc.gnu.org Received: (qmail 20443 invoked by uid 48); 23 Jun 2013 12:25:36 -0000 From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/57684] [c++11] Lambda is not convertible to std::function Date: Sun, 23 Jun 2013 12:25:00 -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: 4.8.1 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: redi at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED 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: Message-ID: <bug-57684-4-SJSSHIcDVs@http.gcc.gnu.org/bugzilla/> In-Reply-To: <bug-57684-4@http.gcc.gnu.org/bugzilla/> References: <bug-57684-4@http.gcc.gnu.org/bugzilla/> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2013-06/txt/msg01274.txt.bz2 Content-length: 569 http://gcc.gnu.org/bugzilla/show_bug.cgi?idW684 --- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- Yes, because std::unique_ptr has a special exception that says it can be instantiated with incomplete types, so that should work OK (like your case where the static member is a raw pointer, which prevents unordered_map being instantiated when base<> is instantiated. I hope for GCC 4.9 we can make unordered_map support incomplete types again, so the original code would work, but it doesn't support them currently, which is allowed by the standard.
next prev parent reply other threads:[~2013-06-23 12:21 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-7652-4@http.gcc.gnu.org/bugzilla/> 2011-02-02 1:04 ` alsuren+gcc at gmail dot com 2011-05-09 14:48 ` barnes.leo at gmail dot com 2011-07-29 13:29 ` daniel.marjamaki at gmail dot com 2012-02-21 1:04 ` eric at brouhaha dot com 2012-02-21 1:14 ` eric at brouhaha dot com 2012-07-14 4:55 ` pinskia at gcc dot gnu.org 2012-07-14 11:54 ` redi at gcc dot gnu.org 2012-07-14 15:15 ` david at doublewise dot net 2012-09-17 22:02 ` alexfh at google dot com 2012-09-18 11:12 ` manu at gcc dot gnu.org 2012-11-26 22:49 ` arthur.j.odwyer at gmail dot com 2012-11-26 23:03 ` arthur.j.odwyer at gmail dot com 2013-06-23 6:44 ` dcb314 at hotmail dot com 2013-06-23 10:38 ` manu at gcc dot gnu.org 2013-06-23 12:21 ` jasonwucj at gmail dot com [this message] 2014-02-16 13:18 ` jackie.rosen at hushmail dot com 2014-04-30 15:45 ` michael.chapman at cortus dot com 2014-04-30 16:09 ` mw_triad at users dot sourceforge.net 2014-04-30 16:10 ` manu at gcc dot gnu.org 2014-04-30 16:18 ` fweimer at redhat dot com 2014-04-30 16:23 ` mpolacek at gcc dot gnu.org 2014-04-30 16:35 ` alexfh at google dot com 2014-04-30 16:40 ` manu at gcc dot gnu.org 2014-04-30 17:04 ` mw_triad at users dot sourceforge.net 2014-04-30 17:20 ` michael.chapman at cortus dot com 2014-09-23 7:25 ` m.j.thayer at googlemail dot com [not found] <bug-7652-1366@http.gcc.gnu.org/bugzilla/> 2010-03-04 20:48 ` pinskia at gcc dot gnu dot org [not found] <20020820073602.7652.ac131313@redhat.com> 2004-07-29 9:43 ` brendan at zen dot org
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