Re: [Tuxnes-devel] *.h: extern int function() VS int function().

[Jason D. S. <jd...@us...>]

Jason Dorje Short wrote:
> Mike Mestnik wrote:
> 
>> For functions maby not, however this is what I got...
>> /usr/bin/ld: Warning: size of symbol `emulators' changed from 44 in
>> controller.o to 132 in emulator.o
>> /usr/bin/ld: Warning: size of symbol `renderers' changed from 36 in
>> controller.o to 252 in renderer.o
>> /usr/bin/ld: Warning: size of symbol `sounders' changed from 28 in emu.o
>> to 84 in sounder.o
>>
>> So things that are extern should stay(and be) extern.
> 
> Variables have to be extern.  Functions need not be.

"Size of symbol changed" => this may actually be a bug.  I've seen this 
before when some header files aren't included right.

Say there is stdbool.h with:

   typedef bool char
   #define HAVE_BOOLEAN

Say you've got a header tuxtype.h with

   #ifndef HAVE_BOOLEAN
   # define bool int
   #endif

   struct var {
     bool p, q;
   };

   extern struct var var;

Now you have one tuxtype.c file:

   #include <stdbool.h>
   #include "tuxtype.h"

   struct var;

and another func.c file:

   #include "tuxtype.h"

   int func()
   {
     var.p = TRUE;
     var.q = FALSE;
   }

now func() will completely not work because it thinks bool is an int, 
whereas in the declaration in tuxtype.c it is a char.  This is almost 
impossible to track down.  But it _could_ give an error message like the 
one you have above.  The solution of course is that <stdbool.h> must be 
included in tuxtype.h.

I think leaving the extern declaration out of the variable may give an 
error, but it shouldn't be the one you got...

jason