[Bug c/54037] New: Warn pointer to integer cast for ilp32

[Bug c/54037] New: Warn pointer to integer cast for ilp32

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54037

             Bug #: 54037
           Summary: Warn pointer to integer cast for ilp32
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: hjl.tools@gmail.com


On Linux/x86-64,

[hjl@gnu-6 tmp]$ cat x.c
unsigned long long
foo (void *p)
{
  return (long) p;
}
[hjl@gnu-6 tmp]$

and

[hjl@gnu-6 tmp]$ cat y.c
unsigned long long
foo (void *p)
{
  return (unsigned long) p;
}
[hjl@gnu-6 tmp]$ 

generate the same code with gcc -m64 since size of long == size of
long long.  However, they are different with "gcc -mx32" and x.c may
be incorrect.  It is desirable to issue a warning when casting from
pointer to signed integer and then to unsigned integer of different
size.

[Bug c/54037] Warn pointer to signed integer cast for ilp32

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54037

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> 2012-07-19 21:50:33 UTC ---
Created attachment 27836
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27836
A patch to add -Wpointer-to-signed-int-cast

[Bug c/54037] Warn pointer to signed integer cast for ilp32

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54037

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-07-19 21:55:24 UTC ---
(In reply to comment #1)
> Created attachment 27836 [details]
> A patch to add -Wpointer-to-signed-int-cast

This won't work for intptr_t which is a signed integer type.

[Bug c/54037] Warn pointer to signed integer cast for ilp32

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54037

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> 2012-07-19 22:04:39 UTC ---
(In reply to comment #2)
> (In reply to comment #1)
> > Created attachment 27836 [details]
> > A patch to add -Wpointer-to-signed-int-cast
> 
> This won't work for intptr_t which is a signed integer type.

-Wpointer-to-signed-int-cast will issue a warning for

[hjl@gnu-6 pr54037]$ cat foo.c
#include <stdint.h>

unsigned long long
foo (void *p)
{
  return (intptr_t) p;
}
[hjl@gnu-6 pr54037]$ 

-Wpointer-to-signed-int-cast is used to help catch the potential
point to signed integer cast issue.  It shouldn't be turned on
by default.

[Bug c/54037] Warn pointer to signed integer cast for ilp32

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54037

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-07-19 23:44:59 UTC ---
We have this request a while back and it was rejected for the same reason why I
said it won't work for intptr_t (though I cannot find the discussion).

[Bug c/54037] Warn pointer to signed integer cast for ilp32

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54037

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #27836|0                           |1
        is obsolete|                            |

--- Comment #5 from H.J. Lu <hjl.tools at gmail dot com> 2012-08-14 18:04:35 UTC ---
Created attachment 28016
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28016
A patch to add -Wpointer-to-signed-int-cast

This patch only warns when ptr_mode != word_mode.