Re: imagemagick support on W32

[Jason Rumney <jasonr@gnu.org>]

joakim@verona.se writes:

> Im not really sure, but from reading image.c it seems that on non w32
> plattforms the library stubs are just compiled in and called directly,
> which means not having the library there would be runtime linkage error.
>
> On w32 something different seems to happen, but no real effort seems to
> be done to avoid errors if the desired library isnt there. I might be
> wrong.

If the desired library is not there, then image-type-available-p will
return nil for that image type (as if the library support were not
compiled in). That should be sufficient to avoid errors.

On other platforms, a missing library will result in Emacs failing to
start, but since modern GNU/Linux systems have good packaging tools that
resolve dependencies well, this shouldn't be a problem (and it shouldn't
be a problem for users who compile Emacs themselves unless they later
remove a library that was there before).