Re: [lwip-users] lwIP compiling warning message.

[David Empson]

"Bill Yang" <address@hidden> wrote:
> I am compiling a demo project which is FreeRTOS + lwIP (webserver demo) + 
> Keil(RVMDK) + Luminary6965.
> I got a compiling warning message below.
>
> ..\Common\ethernet\lwip-1.3.0\contrib\port\FreeRTOS\LM3S\arch/sys_arch.h(62): 
> warning:  #1295-D:
> Deprecated declaration sys_set_default_state - give arg types
>
> I wonder if any one have the ideal how to correct.

That particular file is not part of LWIP - it is supplied by whoever ported 
LWIP to your particular hardware, compiler and operating system. I can't see 
a function of that name mentioned in core LWIP or the reference ports, so it 
is very specific to your port, and the only people here who might be able to 
help directly are those who are using the same platform as you.

I don't have the source code, so I can only speculate, but educated 
guesswork suggests that the compiler is complaining about a function 
prototype which has not provided a list of arguments. That was the old-style 
form of function declaration prior to the introduction of ANSI C, so you 
could declare the return type of a function. With an ANSI C compiler, the 
function prototype must also specify the list of argument types. If the 
function has no arguments, the prototype must specify an argument list of 
(void).

C++ chose to use an empty argument list as meaning "function has no 
arguments", so a possible explanation is that someone who usually programs 
in C++ added a prototype in sys_arch.h for a function with no arguments, and 
forgot that C requires the argument list to be (void).

To find out what should go in the argument list, have a look at the 
implementation of the function, probably in sys_arch.c, and copy its 
declaration line into sys_arch.h, replacing the faulty prototype.

You should report this to the supplier of your LWIP port, as it is a bug in 
their header file.