stdint.h & machine/types.h Header file redefinitions

[Ralf Corsepius]

On Wed, 2003-11-19 at 05:10, Derick Hammond wrote:
> Hello All:
> 
> I have come up with a redefinition warning when I started using the 
> stdint.h header file.
> 
> A little background:
> 
> I use the multilib compiled version of the RTEMS libraries for m68k, and my 
> own build system that  links to the appropriate libraries.

Then you're on your own.

>   Much like using 
> the AMX RTOS, or any commercial RTOS for that matter.  :-)


> The current warning that I get is:
> 
> /opt/rtems-4.6/bin/m68k-rtems-gcc -m5200 -O4 -fomit-frame-pointer -Wall -g 
> -ansi -fasm -DBOOTSTRAP 
> -I/home/derickh/cvs_wa/DataVault_Firmware/devtools/rtems/m68k-rtems/lib/include 
> -I/home/derickh/cvs_wa/DataVault_Firmware/firmware/include 
> -I/home/derickh/cvs_wa/DataVault_Firmware/firmware/rom_start 
> -I/home/derickh/cvs_wa/DataVault_Firmware/firmware/startup -o 
> /home/derickh/cvs_wa/DataVault_Firmware/firmware/../library/rom_objs/rom_start/main.o 
> -c /home/derickh/cvs_wa/DataVault_Firmware/firmware/startup/main.c
> In file included from 
> /home/derickh/cvs_wa/DataVault_Firmware/devtools/rtems/m68k-rtems/lib/include/stdint.h:16,
>                   from 
> /home/derickh/cvs_wa/DataVault_Firmware/devtools/rtems/m68k-rtems/lib/include/rtems/rtems/types.h:26,
>                   from 
> /home/derickh/cvs_wa/DataVault_Firmware/devtools/rtems/m68k-rtems/lib/include/rtems.h:39,
>                   from 
> /home/derickh/cvs_wa/DataVault_Firmware/firmware/include/tod/tod.h:33,
>                   from 
> /home/derickh/cvs_wa/DataVault_Firmware/firmware/startup/main.c:32:
> /home/derickh/cvs_wa/DataVault_Firmware/devtools/rtems/m68k-rtems/lib/include/rtems/stdint.h:21: 
> warning: redefinition of `int8_t'
> /opt/rtems-4.6/m68k-rtems/include/machine/types.h:18: warning: `int8_t' 
> previously declared here
> /home/derickh/cvs_wa/DataVault_Firmware/devtools/rtems/m68k-rtems/lib/include/rtems/stdint.h:22: 
> warning: redefinition of `int16_t'
> /opt/rtems-4.6/m68k-rtems/include/machine/types.h:17: warning: `int16_t' 
> previously declared here
> /home/derickh/cvs_wa/DataVault_Firmware/devtools/rtems/m68k-rtems/lib/include/rtems/stdint.h:23: 
> warning: redefinition of `int32_t'
> /opt/rtems-4.6/m68k-rtems/include/machine/types.h:15: warning: `int32_t' 
> previously declared here
> /home/derickh/cvs_wa/DataVault_Firmware/devtools/rtems/m68k-rtems/lib/include/rtems/stdint.h:24: 
> warning: redefinition of `int64_t'
> /opt/rtems-4.6/m68k-rtems/include/machine/types.h:11: warning: `int64_t' 
> previously declared here
> 
> I have had a quick investigation and have found that machine/types.h seems 
> to only be used in cpukit/libnetworking.  Is this correct?

Yes and no.

machine/types.h is one of RTEMS fundamental and essential internal
system headers that is used all over the place. It is indirectly
included at various places.

>   If so can 
> libnetworking be updated to use stdint.h instead?
I wish it could be, but ...

... you have entered muddy ground here were the problems reach much
deeper than you probably expect.

* libnetworking and other parts of the sources are BSD-sources. BSD has
its own system for fixed-size types. 

* stdint.h is c99. newlib is c89, machine/types.h is part of newlib.
I.e. all parts of 

* Historically, RTEMS has been using it own type-system for fixed size
types.

All this accumulates inside of libnetworking, where all fixed size type
systems are used simultaneously and ... actually clash ...

So what actually would be required is to change libnetworking from using
BSD-types to c99 types, to convert RTEMS as a whole to c99 types, and
find a way to implement stdint.h inside of RTEMS to avoid problems with
gcc and newlib. 

This change is on my agenda for 4.7.0, once 4.6.0 is released. 

The stdint.h implementation in 4.6.0pre is a preliminary and not fully
functional initial attempt to implement this, but is far from being
complete.

> I am happy to do a patch for rtems-4.6.0pre5 if I can get some feedback on 
> what would be considered the best way to solve this issue.
I have spent more than a few hours on this issue, and wish I knew that.

My current strategy for 4.7.0 to implement this, is:
* let stdint.h types be derived from the RTEMS type system.
* replace all occurrences of the RTEMS type system by stdint.h types.
* remove the BSD-fixed-type system (this comprises converting
libnetworking to using stdint.h)

I have many patches related to this pending in my local sources, and
don't want commit them to the official development sources before 4.6.0
is released.

Ralf