Re: [MiNT] [Highwire] gcc4

[m0n0 <ole@monochrom.net>]

Am Sonntag, den 05.09.2010, 20:28 +0200 schrieb Peter Slegg
<p.slegg@scubadivers.co.uk>:


> I have just "fixed" them by making more use of CHAR*  in the function
> interface.


Oh, now I see "buffer" is an CHAR... so converting it to an CHAR* is
not good! And my example wasn't, too. 
It should be like this:

decGif_read (IMGINFO info, CHAR buffer)
{ 
  GifPixelType *pixelType = (GifPixelType*)&buffer;   
...
!

You can't just change an function argument from CHAR to CHAR* - that's
completely different stuff!
An CHAR occupies 1 BYTE, but an CHAR* is 4 Bytes long...

> I have just hit these which I am not familiar with:
> 
> error: cast discards qualifiers from pointer target type

> something to do with volatiles.

Most time you get this "error" is because you pass an "const char * "
to an function that needs an char*...
So doing that cast manually should make gcc happy. 
Strings defined in structs are often const char * - without explicitly
saying so. It's because you define the string somewhere in the
sources.... 

> 
> I have just tried compiling without -Wall as an experiment and it fails
> with a real error with the last, nasty line here:

No, it's not just the last line... 

>                 *p_answ++              /*[0]*/ = GS_REPLY;
>                 *p_answ++              /*[1]*/ = gl_apid;
>                 *p_answ++              /*[2]*/ = 0;
>                 *((long **)p_answ)++/*[3..4]*/ = gsi_;
> 
> AEI.c: In function 'process_messages':
> AEI.c:1555:5: error: lvalue required as increment operand
> AEI.c:1559:5: error: lvalue required as increment operand


> It's trying to asign a value to something that has been ++ incremented
> so is itself a value. Not good. Should it be split into two
> lines and values assigned to p_answ 3 and 4 or just 4 ?

I think you should get informed about the data that is getting handled,
comment the above line out, write your own line of code - and if it
works, than it's fine .
No, I think just assigning the half side of an long ptr will be the
wrong way. 

Greets,
m