Purge and delete modules if after_compile/2 callback fails

[sabiwara]

This probably doesn't have an impact in regular use cases, but it should fix the following gotcha in Livebook: livebook-dev/livebook#3162.

I'm not sure if I'm missing any case where we might want to keep a module for which the callback failed.

[zachdaniel]

At some point it was explained to me that after_verify callbacks must not raise errors/crash. Does this make that not a problem anymore?

[sabiwara]

I remember this was discussed at some point indeed... perhaps the issue is to fix ExUnit.Case then to raise at a different step?

[josevalim]

I remember this was discussed at some point indeed... perhaps the issue is to fix ExUnit.Case then to raise at a different step?

Yes! Or make it warn.

[josevalim]

Sorry, I just realized this is about __after_compile__, not __after_verify__. __after_verify__ cannot fail, because it runs at different moments, and after bytecode has been written to disk, but __after_compile__ arguably can as it always runs in a very specific scenario and it effectively aborts compilation.

[sabiwara]

Indeed I made a mistake in the description, apologies for the confusion.

I realized the same thing after going back to the @after_verfiy docs:

Furthermore, after verification callbacks are not expected to raise. Given they run after the code is compiled, artifacts have already been written to disk, and therefore raising does not effectively halt compilation and may leave unused artifacts on disk. If you must raise, use @after_compile or other callback.

[sabiwara]

Sorry I merged after renaming the PR, but the commit still got merged with the wrong commit message 😢