I hope I wasn't too much pre-emptive... 🙋 let me know if I should draft this PR to avoid a premature merge 😵

Thanks for the PR! I assume you tested that the plugin still works? We definitely need to add tests at some point, but currently, it's necessary to test changes manually.

I did check it with 1.5.0 (the newest commit of MkDocs).
The PR is supposed to be merged after you change the dependency to MkDocs 1.5.0, merging it now would lead to an error.
That's why I second guessed myself in the other message, as I might've jumped the gun.
To make it work for both now and 1.5.0 would require comparing MkDocs module versions (as the API changes), and since you make releases on top of MkDocs you don't have to do that, as you always know what version is shipped in the dependencies.
I shall just draft it for now to avoid confusion. If I miss the 1.5.0 and don't undraft it before you change the dependencies you can always replicate the changes/merge the commit via git tools other than GitHub ✌️

Perfect, thanks for the explanation and thanks for your work! We'll merge it as soon as MkDocs 1.5.0 is released. I understand that without merging it, everything will keep working as expected, except there are now deprecation warnings printed to stdout. That's absolutely fine.

To make it work for both now and 1.5.0 would require comparing MkDocs module versions (as the API changes)

Actually, this statement turned out to be incorrect, because I had to implement support for both 1.5.0 and <1.5.0 in the mkdocs-minify-plugin. With the right order of conditionals, it's possible to use the API change as the deciding factor of which part of the code to run.

https://github.com/kamilkrzyskow/mkdocs-minify-plugin/blob/bc7e1d8339318ed823aeed9e1aaa4f83c442eb30/mkdocs_minify_plugin/plugin.py#L163-L175

I still think that there is no need for this kind of conditional in this project as you decide on which version of MkDocs you depend on. I just thought that the other method is worth mentioning ✌️

MkDocs 1.5.0 is out. We'll be updating to MkDocs >= 1.5.0 as it's out now and release a bugfix release shortly. Material for MkDocs 9.2.x will also depend on MkDocs 1.5.0 and will be considered stable soon.

Great, then I will just open this PR again and let you decide when to merge it 💪

Thanks again! We'll issue 9.1.20 and 9.2.0b2 in a moment.

@squidfunk
I see that the MkDocs dependency is still 1.4.2

    if theme.custom_dir:
       ^^^^^^^^^^^^^^^^
AttributeError: 'Theme' object has no attribute 'custom_dir'

and since you make releases on top of MkDocs you don't have to do that, as you always know what version is shipped in the dependencies

I said that previously, because I expected you'd update the dependency in the requirements.txt, sorry for not being clear enough 😞

Hmm, okay, so I misunderstood this then. What I did: I merged your PR and tested with MkDocs 1.4.3 (which I had on my system) if the build still works when I add the social plugin – all good. Then, I merged the PR, as I assumed that it's backward compatible. I think it was because I had a fresh cache. We'll bump 9.1 to MkDocs 1.5.0 then and issue a new release.