pkg-config dependency missing

[ghost]

Seems like at least one other person had the same problem:
#99
So a line in https://github.com/mozilla/mozjpeg/blob/master/BUILDING.txt would be nice.
Thanks :)

[kornelski]

Ideally the pkg-config dependency itself should be optional (just don't build PNG when pkg-config is missing), but my autotools-fu is to weak for this.

[dwbuiten]

That's kind of contrary to the point of autotools. Users aren't supposed to be generating configure in the first place. See #86.

[kornelski]

I'm not saying users should be generating configure, but that configure file you generate should ideally work with or without pkg-config.

If there's pkg-config and libpng - configure PNG. If either one is missing - skip PNG support.

Is that possible?

[bdaehlie]

I think we should resolve this by shipping a tarball with a pre-generated configure. I'll file a bug on that. We'll need to update our build instructions to include from-git and from-tarball instructions.

[dwbuiten]

I'm not saying users should be generating configure, but that configure file you generate should ideally work with our without pkg-config.

That is already the case. The problem only happens when configure is incorrectly generated due to the pkg-config macros being missing.

[bdaehlie]

Release now includes a generated configure.