Re: Warnings in mingw64 build on emacs-28 branch

[Óscar Fuentes]

Eli Zaretskii <eliz@gnu.org> writes:

>> As for the warning, I think it is because a const void* is passed to
>> VirtualQuery pointing to an uninitialized object.
>
> I don't understand why the compiler thinks the object must be
> initialized for its pointer to be valid.  Does the compiler assume
> something about what VirtualQuery does?  Why does it think the
> function will dereference the pointer?

The warning says "may be used uninitialized". The compiler doesn't know,
it sees something suspicious and speaks up. That's with -Wall, without
it, the compiler remains silent.

I guess the MinGW headers should be annotated with whatever decoration
gcc uses to convey that the pointer is not dereferenced.

Or we can initialize `m' to zero, which will silence the warning and is
a good practice in general when working with the Windows API.