[CMake] howto check for res_init() ?

[Brad King]

Alexander Neundorf wrote:
> Hi, 
>  
> I tried to check for the function res_init() 
>  
> with  
> CHECK_FUNCTION_EXISTS(res_init HAVE_RES_INIT) 
>  
> This always fails, although it shouldn't. 
> The problem is this line in resolv.h: 
>  
> /usr/include$ grep res_init * 
> resolv.h:#define res_init               __res_init 
> resolv.h:int            res_init __P((void)); 
>  
> I.e. resolv() is only a macro, the actual function name is __res_init(), 
> but the compiler/linker doesn't know this since resolv.h is not included 
> when compiling the test program for CHECK_FUNCTION_EXISTS(). 
> So what can I do ? 

Use the CheckSymbolExists module.  It accounts for the possibility that 
the symbol is defined by a macro.

-Brad