[Bug c/43633] New: sizeof returns wrong size for large long long values when using -std=c99

[Bug c/43633] New: sizeof returns wrong size for large long long values when using -std=c99

[sje at cup dot hp dot com]

If I compile a program with -std=c99 and do a sizeof of a constant that is
larger then LONG_LONG_MAX but smaller then ULONG_LONG_MAX I get 16 instead of
8.  For values larger then ULONG_LONG_MAX I get 8.  I can reproduce this on x86
Linux and IA64 HP-UX (and probably other systems).    Here is a test case that
should show the problem on any systems where LONG LONG is 8 bytes.  Compiled
without -std=c99 all the prints will print '8', with '-std=c99' the middle two
prints will print out 16 instead of 8.  Reproducable with ToT and going back to
at least 4.1.0.

#include <stdio.h>
main()
{
        /* LONG_LONG_MAX */
        printf("%ld\n", sizeof(9223372036854775807LL));
        /* LONG_LONG_MAX + 1 */
        printf("%ld\n", sizeof(9223372036854775808LL));
        /* ULONG_LONG_MAX as a long long type */
        printf("%ld\n", sizeof(18446744073709551615LL));
        /* ULONG_LONG_MAX + 1 as a long long type */
        printf("%ld\n", sizeof(18446744073709551616LL));
}


-- 
           Summary: sizeof returns wrong size for large long long values
                    when using -std=c99
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: sje at cup dot hp dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43633

[Bug c/43633] sizeof returns wrong size for large long long values when using -std=c99

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2010-04-02 23:04 -------
t.c:7:32: warning: integer constant is so large that it is unsigned
t.c:9:32: warning: integer constant is so large that it is unsigned
t.c:11:32: warning: integer constant is too large for its type


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43633

[Bug c/43633] sizeof returns wrong size for large long long values when using -std=c99

[schwab at linux-m68k dot org]

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------- Comment #2 from schwab at linux-m68k dot org  2010-04-03 09:16 -------
§6.4.4.1 Integer constants:

If an integer constant cannot be represented by any type in its list, it may
have an extended integer type, if the extended integer type can represent its
value. If all of the types in the list for the constant are signed, the
extended integer type shall be signed.

Thus 9223372036854775808LL will be of some signed extended type, since it does
not fit in long long.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43633

[Bug c/43633] sizeof returns wrong size for large long long values when using -std=c99

[truedfx at gentoo dot org]

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------- Comment #3 from truedfx at gentoo dot org  2010-04-05 12:54 -------
(In reply to comment #2)
> §6.4.4.1 Integer constants:
> 
> If an integer constant cannot be represented by any type in its list, it may
> have an extended integer type, if the extended integer type can represent its
> value. If all of the types in the list for the constant are signed, the
> extended integer type shall be signed.
> 
> Thus 9223372036854775808LL will be of some signed extended type, since it does
> not fit in long long.

It *may* have an extended integer type. If it doesn't (and it doesn't: gcc
doesn't have any of the standard's extended integer types, see
http://gcc.gnu.org/onlinedocs/gcc-4.4.3/gcc/Integers-implementation.html), such
a constant is simply invalid, and gcc, after reporting that, is free to make
the code behave however it likes. At least, as far as the standard is
concerned.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43633