bug#27810: NS runtime feature detection

["Charles A. Roelli" <charles@aurox.ch>]

Shouldn't MIN_ALLOWED be MIN_REQUIRED?  As in here:

+#if defined (NS_IMPL_COCOA) \
+  && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_7
+#if MAC_OS_X_VERSION_MIN_ALLOWED < MAC_OS_X_VERSION_10_7

There are a few more places that have a MIN_ALLOWED thing.  This
always trips me up, so I'm not sure.

And also, it's apparently feasible to do a runtime check for a
specific macOS, according to this:

https://developer.apple.com/library/content/documentation/DeveloperTools/Conceptual/cross_development/Using/using.html#//apple_ref/doc/uid/20002000-SW7

which mentions APPKIT_EXTERN double NSAppKitVersionNumber.  I'm not
sure if they still define this on Sierra, though.  But if they do,
then we can use this to fix the nsmenu.m problem.


On 26/07/2017 23:57, Alan Third wrote:
> On Mon, Jul 24, 2017 at 09:44:04PM +0100, Alan Third wrote:
>>> I'm confused why the macro call you wrote doesn't prevent this. But
>>> when I change it to #if MAC_OS_X_VERSION_MIN_ALLOWED <=
>>> MAC_OS_X_VERSION_10_6, then it compiles.  This min/max stuff always
>>> confuses me...
>> I’m unclear where we should be using MIN_REQUIRED vs MAX_ALLOWED, but
>> I think we’re OK with MAX everywhere for what we’re doing. I’ve just
>> used MAX in both my new macros.
> I think I finally worked it out by reading macfont.m. I’ve attached
> YET ANOTHER version of this which doesn't use any custom macros.
>
> To compile for multiple versions you do something like:
>
> ./configure --with-ns CFLAGS="-DMAC_OS_X_VERSION_MIN_REQUIRED=1070 -DMAC_OS_X_VERSION_MAX_ALLOWED=101200 -g -O3"
>
> By default max and min are set to the version you’re running on,
> afaict. Please be aware that 10.6 isn’t fully compatible with this at
> the moment, as there is at least one place (nsmenu.m:535) where
> there’s a bug fix for it that I can’t see an immediate way of making
> dynamic.
>
> Additionally the native fullscreen stuff is based on a simple check
> against MAX. I expect I’ll be able to fix that with a bit of work,
> though.
>
> I’d be interested to see if this builds on systems lower than 10.10
> with the above configure command. There are probably bits and pieces
> I’ve not quite got right.
>