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* [Bug c/31977] New: can return OK from "int main()" without a return statement by using a goto before the return
@ 2007-05-17 15:46 bmcfadden at cdp dot com
2007-05-17 15:48 ` [Bug c/31977] " bmcfadden at cdp dot com
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: bmcfadden at cdp dot com @ 2007-05-17 15:46 UTC (permalink / raw)
To: gcc-bugs
I'm using gcc 3.4.5, and I was looking into a weird condition. The following
program compiles OK:
#include <stdio.h>
int alloc()
{
return 0;
}
int main(int argc, char* argv[])
{
printf("Testing!\n");
if(alloc() == 0)goto Radhe;
return 0;
Radhe:
printf("Hello\n");
}
The result is a program which prints "Testing", then "Hello", and then exits.
I and a few other people expect that the compiler would generate an error
during compile, because main should return an int, and not all code paths have
a return statement; however, both gcc and msvc are compiling this OK.
added note: this bug was recently discussed on the NTDEV mailing list.
--
Summary: can return OK from "int main()" without a return
statement by using a goto before the return
Product: gcc
Version: 3.4.5
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: bmcfadden at cdp dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31977
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/31977] can return OK from "int main()" without a return statement by using a goto before the return
2007-05-17 15:46 [Bug c/31977] New: can return OK from "int main()" without a return statement by using a goto before the return bmcfadden at cdp dot com
@ 2007-05-17 15:48 ` bmcfadden at cdp dot com
2007-05-17 15:52 ` bmcfadden at cdp dot com
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: bmcfadden at cdp dot com @ 2007-05-17 15:48 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from bmcfadden at cdp dot com 2007-05-17 16:48 -------
Created an attachment (id=13571)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13571&action=view)
The file from -save-temps
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31977
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/31977] can return OK from "int main()" without a return statement by using a goto before the return
2007-05-17 15:46 [Bug c/31977] New: can return OK from "int main()" without a return statement by using a goto before the return bmcfadden at cdp dot com
2007-05-17 15:48 ` [Bug c/31977] " bmcfadden at cdp dot com
@ 2007-05-17 15:52 ` bmcfadden at cdp dot com
2007-05-17 15:54 ` bmcfadden at cdp dot com
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: bmcfadden at cdp dot com @ 2007-05-17 15:52 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from bmcfadden at cdp dot com 2007-05-17 16:52 -------
Created an attachment (id=13572)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13572&action=view)
the assembly (.s) file
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31977
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/31977] can return OK from "int main()" without a return statement by using a goto before the return
2007-05-17 15:46 [Bug c/31977] New: can return OK from "int main()" without a return statement by using a goto before the return bmcfadden at cdp dot com
2007-05-17 15:48 ` [Bug c/31977] " bmcfadden at cdp dot com
2007-05-17 15:52 ` bmcfadden at cdp dot com
@ 2007-05-17 15:54 ` bmcfadden at cdp dot com
2007-05-17 17:53 ` pinskia at gcc dot gnu dot org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: bmcfadden at cdp dot com @ 2007-05-17 15:54 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from bmcfadden at cdp dot com 2007-05-17 16:54 -------
Reading specs from /usr/lib/gcc/i386-redhat-linux/3.4.5/specs
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--disable-checking --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-java-awt=gtk --host=i386-redhat-linux
Thread model: posix
gcc version 3.4.5 20051201 (Red Hat 3.4.5-2)
--
bmcfadden at cdp dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bmcfadden at cdp dot com
GCC host triplet| |i386-redhat-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31977
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/31977] can return OK from "int main()" without a return statement by using a goto before the return
2007-05-17 15:46 [Bug c/31977] New: can return OK from "int main()" without a return statement by using a goto before the return bmcfadden at cdp dot com
` (2 preceding siblings ...)
2007-05-17 15:54 ` bmcfadden at cdp dot com
@ 2007-05-17 17:53 ` pinskia at gcc dot gnu dot org
2007-05-17 19:39 ` bangerth at dealii dot org
2007-05-17 19:45 ` pinskia at gcc dot gnu dot org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-05-17 17:53 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from pinskia at gcc dot gnu dot org 2007-05-17 18:53 -------
[pinskia-laptop:~/src] pinskia% gcc -Wreturn-type t.c
t.c: In function 'main':
t.c:15: warning: control reaches end of non-void function
This code is only undefined at runtime which means you cannot error out.
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |INVALID
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31977
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/31977] can return OK from "int main()" without a return statement by using a goto before the return
2007-05-17 15:46 [Bug c/31977] New: can return OK from "int main()" without a return statement by using a goto before the return bmcfadden at cdp dot com
` (3 preceding siblings ...)
2007-05-17 17:53 ` pinskia at gcc dot gnu dot org
@ 2007-05-17 19:39 ` bangerth at dealii dot org
2007-05-17 19:45 ` pinskia at gcc dot gnu dot org
5 siblings, 0 replies; 7+ messages in thread
From: bangerth at dealii dot org @ 2007-05-17 19:39 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from bangerth at dealii dot org 2007-05-17 20:38 -------
Both the C99 standard (section 5.1.2.2.3) and the C++ standard (3.6.1/5)
say that if you hit the end of the main() function, then this is equivalent
to a "return 0;" statement.
W.
--
bangerth at dealii dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bangerth at dealii dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31977
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/31977] can return OK from "int main()" without a return statement by using a goto before the return
2007-05-17 15:46 [Bug c/31977] New: can return OK from "int main()" without a return statement by using a goto before the return bmcfadden at cdp dot com
` (4 preceding siblings ...)
2007-05-17 19:39 ` bangerth at dealii dot org
@ 2007-05-17 19:45 ` pinskia at gcc dot gnu dot org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-05-17 19:45 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from pinskia at gcc dot gnu dot org 2007-05-17 20:45 -------
(In reply to comment #5)
> Both the C99 standard (section 5.1.2.2.3) and the C++ standard (3.6.1/5)
> say that if you hit the end of the main() function, then this is equivalent
> to a "return 0;" statement.
C90 is different from both of those and it is just undefined behavior there.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31977
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2007-05-17 19:45 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2007-05-17 15:46 [Bug c/31977] New: can return OK from "int main()" without a return statement by using a goto before the return bmcfadden at cdp dot com
2007-05-17 15:48 ` [Bug c/31977] " bmcfadden at cdp dot com
2007-05-17 15:52 ` bmcfadden at cdp dot com
2007-05-17 15:54 ` bmcfadden at cdp dot com
2007-05-17 17:53 ` pinskia at gcc dot gnu dot org
2007-05-17 19:39 ` bangerth at dealii dot org
2007-05-17 19:45 ` pinskia at gcc dot gnu dot org
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