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

[Andy Moreton <andrewjmoreton@gmail.com>]

On Sat 11 Aug 2018, Andy Moreton wrote:

> On Sat 11 Aug 2018, Eli Zaretskii wrote:
>
>>> From: Andy Moreton <andrewjmoreton@gmail.com>
>>> 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.

For the record, with get_proc_address like this:

    typedef void (*VOIDFNPTR)(void);

    VOIDFNPTR
    get_proc_address (HINSTANCE handle, LPCSTR fname)
    {
      return (VOIDFNPTR) GetProcAddress (handle, fname);
    }

Then the following does not trigger the warning:

 	  s_pfn_Get_Module_HandleExA =
	    (GetModuleHandleExA_Proc) get_proc_address (hm_kernel32,
                                                        "GetModuleHandleExA");