[Bug c/46907] New: printf width not properly working for negative numbers which are variables

["adrian.hawryluk at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46907

           Summary: printf width not properly working for negative numbers
                    which are variables
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: adrian.hawryluk@gmail.com
              Host: Windows XP SP2
            Target: mingw32
             Build: 4.5.0


#include <stdio.h>
#include <math.h>

int main()
{
    char a = 0x7f;
    printf("%02x ", 0x80);
    printf("%02x ", (char)0x80);
    printf("%02x ", a + 1);
    printf("%02x ", ++a);
    printf("%02x ", a);
    return 0;
}

Result:
80 ffffff80 80 ffffff80 ffffff80

Given this test, it looks like it might have to do with promotion to an int (or
is it long?), which is fine, except that I used the width to stop this problem
from happening.  Looks sketchy.

C:\>gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=c:/mingw/bin/../libexec/gcc/mingw32/4.5.0/lto-wrapper.exe
Target: mingw32
Configured with: ../gcc-4.5.0/configure
--enable-languages=c,c++,ada,fortran,objc,obj-c++ --disable-sjlj-exceptions
--with-dwarf2 --enable-shared --enable-libgomp --disable-win32-registry
--enable-libstdcxx-debug --enable-version-specific-runtime-libs
--disable-werror --build=mingw32 --prefix=/mingw

Thread model: win32
gcc version 4.5.0 (GCC)

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A