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

[Eli Zaretskii]

> From: Andy Moreton <address@hidden>
> Date: Sat, 11 Aug 2018 16:02:03 +0100
> 
> On Sat 11 Aug 2018, Eli Zaretskii wrote:
> 
> >> From: Andy Moreton <address@hidden>
> >> Date: Sat, 11 Aug 2018 11:41:20 +0100
> >> 
> >> > OK, I've now done so.  Andrew, please see if this fixes the original
> >> > problem with this warning.
> >> 
> >> Yes, that ha removed that batch of warnings.
> >
> > Thanks for testing.
> >
> >> There are still other warnings: one from -Wformat-overflow and 78 from
> >> -Wcast-function-type.
> >
> > Can you show the warnings from -Wcast-function-type?
> 
> Here are the warnings from commit ec6f588940e5, built with gcc 8.2.0.
> Mostly this seems to be GetProcAddress results, where it complains that
> FARPROC and the desired fuinction type don't match. The gcc manual says
> that casting via "void (*)(void)" can be used to pacify the warning.
> 
> 
>   CC       dynlib.o
> C:/emacs/git/emacs/emacs-26/src/dynlib.c: In function 'dynlib_addr':
> C:/emacs/git/emacs/emacs-26/src/dynlib.c:160:6: warning: cast between 
> incompatible function types from 'FARPROC' {aka 'long long int (*)()'} to 
> 'BOOL (*)(DWORD,  const CHAR *, struct HINSTANCE__ **)' {aka 'int (*)(long 
> unsigned int,  const char *, struct HINSTANCE__ **)'} [-Wcast-function-type]
>       (GetModuleHandleExA_Proc) GetProcAddress (hm_kernel32,
>       ^

Does it help to take the GetProcAddress call in parentheses, like
this:

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

?

If this doesn't help, what about removing the cast entirely?

In any case, I think it's a GCC bug: it thinks we are type-casting the
function being called, which is GetProcAddress, whereas what we really
want to do is cast the _value_ the function returns.

Thanks.