imagemagick: add pkgconfig as a runtime dependency

[ericsagnes]

Fix the pkgconfig runtime dependency for ImageMagick config scripts:

Wand-config --libs 
/run/current-system/sw/bin/Wand-config: line 53: pkg-config: command not found

[lucabrunox]

It's unusual that a package depends on pkg-config at runtime, but I guess that's ok. 👍

[ericsagnes]

As I am quite new to NixOS, review and feedback are welcome.

[edolstra]

Better to postpone this until imagemagick has a proper dev output, since then we can put want-config in the dev output without increasing the closure size of the regular package.

[lucabrunox]

Or maybe put it in propagatedBuildInputs, given that Wand-config ecc. should be used only when building stuff.

[vcunat]

I'm not sure whether ~1.2 MB is important enough, but the splitting might be in master in a month or so...

[ericsagnes]

Or maybe put it in propagatedBuildInputs, given that Wand-config ecc. should be used only when building stuff.

I see, I encountered this problem when trying to build PHP ImageMagick extension so maybe propagatedBuildInputs is a better choice in such case?

[vcunat]

Well, you likely want to have pkgconfig during the extension build anyway, so why not add it in there explicitly. It isn't perfect, but that approach doesn't add pkgconfig to runtime closure.

[ericsagnes]

Well, you likely want to have pkgconfig during the extension build anyway, so why not add it in there explicitly. It isn't perfect, but that approach doesn't add pkgconfig to runtime closure.

That's what I did first, but as it seemed to be an ImageMagick problem, it felt more natural to fix it in ImageMagick.

I will add pkgconfig to the php extension buildInputs for now.

Thanks all for the feedback!

[vcunat]

I agree it would be more natural, and after #7701 it won't cost us extra space in runtime closures.

[joachifm]

Yay or nay on this. Seems like the splitting branch is yet to land, should this still be postponed?

[ericsagnes]

@joachifm no problems with me to postpone this after multiple outputs get merged.

[vcunat]

Probably better to either postpone or port atop that branch (which is possible immediately). I wouldn't be nice to have $out depend on pkgconfig...

[joachifm]

Now that multiple-outputs has been merged, this could be integrated, right?

[ericsagnes]

@joachifm Is there any change needed to make it work it multiple outputs?

[vcunat]

• The "dev" output wasn't split yet.
• Finding pkg-config executable isn't enough... one also needs to find the *.pc files.

See 73f1f5e for details/implementation.