If there's a circular import in my program, I don't want to see an error message, "Cannot import name 'foo'" and then say in my mind, "ah, I'm an experienced Python developer, I know that when Python says that it often means that there's a circular import problem." I want the error message to **say there's a circular import problem**, so (a) I won't have to remember this piece of trivia and (b) less experienced developers won't have to bang their heads on their desks trying to figure out why the import isn't working. 

Bonus points if the error message actually shows which module is trying to import a module that imports itself, so we'll know where to fix.

It's not as simple as it sounds because failures from "from ... import ..." are triggered in the eval loop and not in import and without thinking it through I don't know if you could use the fine-grained import locks to inspect if something is in the middle of being imported or not that way.

New changeset 65366bc8bdc4716ebc361e622590b45a6e5aef07 by Steve Dower (Anthony Sottile) in branch 'master':
bpo-20490: Improve circular import error message (GH-15308)
https://github.com/python/cpython/commit/65366bc8bdc4716ebc361e622590b45a6e5aef07

Thanks for the patch, Anthony!

New changeset 2d5594fac21a81a06f82c3605318dfa96e72398f by Steve Dower in branch '3.8':
bpo-20490: Improve circular import error message (GH-15308)
https://github.com/python/cpython/commit/2d5594fac21a81a06f82c3605318dfa96e72398f

This PR introduced a reference leak tracked in:

https://bugs.python.org/issue38090