Revert "opengl32: Return a NULL pointer for functions requiring unsupported or disabled extensions.".

[Alex Henrie]

2015-11-27 12:15 GMT-07:00 Alex Henrie <alexhenrie24 at gmail.com>:
> 2015-11-27 0:54 GMT-07:00 Alexandre Julliard <julliard at winehq.org>:
>> Sebastian Lackner <sebastian at fds-team.de> writes:
>>
>>> @Alexandre: Just to make sure I tested it in practice, and it indeed solves
>>> the bug. It would be acceptable but 1.8, but wouldn't solve
>>> https://bugs.winehq.org/show_bug.cgi?id=39563 for example. I am aware that
>>> its technically not a Wine bug, but it could still be solved by being less
>>> strict with extension filtering. Both MESA and NVIDIA return valid valid
>>> function pointers in this case.
>>
>> Actually I would argue that it is a Wine bug. If you can get a valid
>> function on Windows even when the extension is missing, you should get
>> one on Wine. Conversely, if you get a NULL pointer on Windows for a
>> missing function, you should get NULL on Wine too.
>>
>> This means that we have a responsibility to properly remap functions and
>> extensions between the Windows and the Unix side. We can't simply
>> forward to the Unix driver and hope that it happens to follow the
>> Windows semantics.
>
> After giving it some thought, I think this could work. As long as
> we're sure that suffixed functions behave identically to their
> unsuffixed counterparts, we should be able to return a function
> pointer to a suffixed function even though a unsuffixed function was
> requested (as long as the suffixed function is advertised in the
> extension list).
>
> This would match both:
> - Windows returning function pointers for unsuffixed functions even
> though the rest of the OpenGL version is not available
> - GLX providing no guarantee that calling a function not defined in
> the GL version or extension list won't crash the program, even though
> an unsuffixed equivalent could work fine
>
> And it would cleanly resolve bugs 38480 and 39563.

Sorry, I meant to say "even though a suffixed equivalent could work fine".

-Alex