warning: implicit declaration of function 'sym_forget' is invalid in C99

[Jeremy Lavergne]

That warning (implicit function declaration) likely means the source code is using a function before having it defined. You’ll need to edit the source (fixes the cause), or ask clang to use an older c standard (fixes only the symptom).

On Jan 8, 2014, at 14:21, zhifeng yang <yangzf01 at gmail.com> wrote:

> 
> I use the following command to compile a .c file and got the error as below.
> 
> cc -DIWORDSIZE=4 -DMAX_HISTORY=25 -DNMM_CORE=0  -c -g  registry.c
> registry.c:60:3: warning: implicit declaration of function 'sym_forget' is invalid in C99 [-Wimplicit-function-declaration]
> sym_forget() ;
> 
> I am sure it is due to the cc flag. But I am not sure which flag causes this error. Can anybody help me? thank you