Re: New warnings on emacs-26 branch with gcc 8.2.0

[Andy Moreton]

On Sat 11 Aug 2018, Eli Zaretskii wrote:

>> From: Andy Moreton <address@hidden>
>> Date: Sat, 11 Aug 2018 19:13:00 +0100
>> 
>> > Does it help to take the GetProcAddress call in parentheses, like
>> > this:
>> >
>> >      s_pfn_Get_Module_HandleExA =
>> >        (GetModuleHandleExA_Proc) (GetProcAddress (hm_kernel32,
>> >                                                   "GetModuleHandleExA"));
>> 
>> Doesn't help - gcc still warns.
>> 
>> > If this doesn't help, what about removing the cast entirely?
>> 
>> Also still warns. This does work:
>> 
>>        s_pfn_Get_Module_HandleExA =
>>          (GetModuleHandleExA_Proc) (void (*)(void))
>>             GetProcAddress (hm_kernel32, "GetModuleHandleExA");
>> 
>> This is sliughtly less ugly and also pacifies the warning:
>> 
>> #define FN_PTR_CAST(fnptrtype, fnptr)                   \
>>           ((fnptrtype) (void (*)(void)) (fnptr))
>> 
>>        s_pfn_Get_Module_HandleExA =
>>             FN_PTR_CAST(GetModuleHandleExA_Proc,
>>                         GetProcAddress (hm_kernel32, "GetModuleHandleExA"));
>
> I'd rather disable the warning around the code which uses these casts.
> Or maybe we should introduce our ownj get_proc_address, which returns
> a (void (*)(void)) pointer.  But that's not for emacs-26, sorry.

Given how many source files are involved, for emacs-26 the simplest
thing is simply to disable -Wcast-function-type in configure.ac.

For master we can leave the warning enabled if the GetProcAddress calls
can be fixed to pacify the warning.

    AndyM