Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.c++ > #83778
| From | Juha Nieminen <nospam@thanks.invalid> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: getline() problem |
| Date | 2022-04-26 11:06 +0000 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <t48jo1$32b$1@gioia.aioe.org> (permalink) |
| References | (8 earlier) <t46np1$5uj$1@dont-email.me> <t480p6$1gdc$1@gioia.aioe.org> <t487du$7ps$1@dont-email.me> <t48de1$11f9$1@gioia.aioe.org> <f65d5129-0b35-4732-b82c-f284726cd66an@googlegroups.com> |
Malcolm McLean <malcolm.arthur.mclean@gmail.com> wrote:
> Basically you want a severe warning, because the programmer might have
> deliberately caused the undefined behaviour because he knows what it
> will do on his platform. He might want to set the carry flag before
> jumping into an assembler routine, for example.
>
> But normally it's best if UB does something dramatic and fatal to normal
> execution, because no results are usually better than wrong results, and
> no executable is usually better than a buggy executable.
One rather interesting example of UB doing something quite unexpected
is this code, when compiled with clang 13.0.0:
//--------------------------------------------
#include <stdio.h>
void f1(void) {
for(int i = 0; i >= 0; i++) {
// Undefined behavior
}
}
void f2(void) {
puts("Formatting /dev/sda1...");
// system("mkfs -t btrfs -f /dev/sda1");
}
void (*volatile p1)(void) = f1;
void (*volatile p2)(void) = f2;
int main(void) {
puts(__VERSION__);
p1();
return 0;
}
//------------------------------------------
That "p1()" might look like it's calling the f1() function, but ends up
executing the f2() function instead (because for some reason this version
of clang compiles f1() into nothing. Not even a 'ret'. And f2() immediately
follows it, so...)
Source: https://bugs.llvm.org/show_bug.cgi?id=49599
Back to comp.lang.c++ | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-23 19:07 +0200
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-23 10:17 -0700
Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-23 19:40 +0200
Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-23 19:59 +0200
Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-23 21:47 +0300
Re: getline() problem Juha Nieminen <nospam@thanks.invalid> - 2022-04-25 06:00 +0000
Re: getline() problem Öö Tiib <ootiib@hot.ee> - 2022-04-25 00:12 -0700
Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 11:40 +0300
Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-25 11:37 -0400
Re: getline() problem Vir Campestris <vir.campestris@invalid.invalid> - 2022-04-25 16:54 +0100
Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-25 12:29 -0400
Re: getline() problem scott@slp53.sl.home (Scott Lurndal) - 2022-04-25 17:29 +0000
Re: getline() problem Manfred <noname@add.invalid> - 2022-04-25 20:17 +0200
Re: getline() problem Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-04-25 10:19 -0700
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 10:41 -0700
Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 21:58 +0300
Re: getline() problem scott@slp53.sl.home (Scott Lurndal) - 2022-04-25 15:56 +0000
Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-25 13:12 -0400
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 11:03 -0700
Re: getline() problem scott@slp53.sl.home (Scott Lurndal) - 2022-04-25 19:05 +0000
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 12:48 -0700
Re: getline() problem Ben <ben.usenet@bsb.me.uk> - 2022-04-25 21:46 +0100
Re: getline() problem Juha Nieminen <nospam@thanks.invalid> - 2022-04-26 05:43 +0000
Re: getline() problem David Brown <david.brown@hesbynett.no> - 2022-04-26 09:36 +0200
Re: getline() problem Juha Nieminen <nospam@thanks.invalid> - 2022-04-26 09:18 +0000
Re: getline() problem Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-04-26 02:47 -0700
Re: getline() problem Juha Nieminen <nospam@thanks.invalid> - 2022-04-26 11:06 +0000
Re: getline() problem David Brown <david.brown@hesbynett.no> - 2022-04-26 15:52 +0200
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-26 07:04 -0700
Re: getline() problem Manfred <noname@add.invalid> - 2022-04-26 16:49 +0200
Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-26 12:01 -0400
Re: getline() problem James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-04-26 11:49 -0400
Re: getline() problem Manfred <noname@add.invalid> - 2022-04-25 20:23 +0200
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 10:33 -0700
Re: getline() problem "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2022-04-25 10:52 -0700
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 11:08 -0700
Re: getline() problem "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2022-04-25 21:18 -0700
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 22:04 -0700
Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 22:06 +0300
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-25 13:02 -0700
Re: getline() problem Barry Schwarz <schwarzb@delq.com> - 2022-04-23 12:54 -0700
Re: getline() problem Montmorency <none@none.com> - 2022-04-23 14:45 -0700
Re: getline() problem Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-04-23 16:49 -0700
Re: getline() problem Ben <ben.usenet@bsb.me.uk> - 2022-04-24 01:04 +0100
Re: getline() problem Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-04-23 18:24 -0700
Re: getline() problem Ben <ben.usenet@bsb.me.uk> - 2022-04-24 03:16 +0100
Re: getline() problem Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-04-24 22:51 -0700
Re: getline() problem Ben <ben.usenet@bsb.me.uk> - 2022-04-25 11:07 +0100
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-23 17:15 -0700
Re: getline() problem Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-04-23 18:23 -0700
Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-24 05:28 +0200
Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-25 12:41 +0200
Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 14:33 +0300
Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-25 18:53 +0200
Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-25 22:08 +0300
Re: getline() problem Jivanmukta <jivanmukta@poczta.onet.pl> - 2022-04-26 09:01 +0200
Re: getline() problem Paavo Helde <eesnimi@osa.pri.ee> - 2022-04-26 11:15 +0300
csiph-web