bug report

[Tom McLintock]

I don't have the list of known bugs, so forgive me if this is a known
one.

The version of gcc I'm using is
Reading specs from
/usr/local/lib/gcc-lib/mips-sgi-irix6.5/egcs-2.91.66/specs
gcc version egcs-2.91.66 19990314 (egcs-1.1.2 release)
on an sgi, and
Reading specs from
/usr/local/lib/gcc-lib/hppa1.1-hp-hpux10.20/egcs-2.91.66/specs
gcc version egcs-2.91.66 19990314 (egcs-1.1.2 release)
on an hp

Here's some code:

mc.h
-----
typedef struct {
  short  red;
  short  green;
  short  blue;
} MapColor;

void ApplyColorByRGB(
#ifdef UseProtos
    int channel,
    int object,
    MapColor mapcol,
    int setflag
#endif
);

mc.c
-----
#include "mc.h"
#include <stdio.h>

void ApplyColorByRGB(
#ifdef UseProtos
    int channel,
    int object,
    MapColor mapcol,
    int setflag
#else
    channel, object, mapcol, setflag
#endif
)
#ifndef UseProtos
    int channel;
    int object;
    MapColor mapcol;
    int setflag;
#endif
{
  printf("channel=%d\nobject=%d\nmapcol={%d, %d, %d}\nsetflag=%d\n",
          channel, object, mapcol.red, mapcol.green, mapcol.blue,
setflag);
}

main.c
-------
#include "mc.h"
#include <stdio.h>

main()
{
  int channel = 1;
  int object = 2;
  int setflag = 4;
  MapColor mapcol;
  mapcol.red = 10000;
  mapcol.green = 20000;
  mapcol.blue = 30000;

  printf("channel=%d\nobject=%d\nmapcol={%d, %d, %d}\nsetflag=%d\n\n",
          channel, object, mapcol.red, mapcol.green, mapcol.blue,
setflag);
  ApplyColorByRGB(channel, object, mapcol, setflag);
  printf("\n\n");
}

the "makefile"
------------
cc -c mc.c
gcc main.c mc.o -o gcc_cc
echo gcc_cc:
gcc_cc
cc main.c mc.o -o cc_cc
echo cc_cc:
cc_cc


output on an sgi
-------------
gcc_cc:
channel=1
object=2
mapcol={10000, 20000, 30000}
setflag=4

channel=1
object=2
mapcol={0, 10000, 20000}
setflag=4


cc_cc:
channel=1
object=2
mapcol={10000, 20000, 30000}
setflag=4

channel=1
object=2
mapcol={10000, 20000, 30000}
setflag=4


output on an hp
-------------
gcc_cc:
channel=1
object=2
mapcol={10000, 20000, 30000}
setflag=4

channel=1
object=2
mapcol={20000, 30000, 2}
setflag=4


cc_cc:
channel=1
object=2
mapcol={10000, 20000, 30000}
setflag=4

channel=1
object=2
mapcol={10000, 20000, 30000}
setflag=4


Notice that when main.c is compiled with gcc, the MapColor struct mapcol
is not passed in to the ApplyColorByRGB function; when main.c is
compiled with the machine's native cc compiler, the struct is passed in
correctly.  Also note that the struct is passed incorrectly in different
ways on each machine.  It looks like a byte-alignment problem to me.

To fix this problem I would ordinarily compile mc.c (actually, the file
that mc.c represents in my application) using gcc, but I don't have the
source code for it.

Please let me know what's going on here.  Thanks!