I'm using Pycharm (2019.1.2 x64) from quite a while and I never changed the standard settings.
The standard settings diplay keywords (def, class, if) in orange, pressing tab will auto complete the keyword and add a space, build-in functions (sum(), map(), print()) are displayed in purple and pressing tab will auto complete the function name, add brackets and move the cursor inside the brackets.
This is the desired behavior and it's what I get when opening any project in Pycharm except one.
In a single project this behavior suddently changed, I did nothing but writing and running code.
I noticed because tab suddently started indenting by 8 spaces instead of 4, no big deal I changed it back to 4 in the bottom of the IDE, but I also noticed that print was seen as a keyword (so orange with no brackets) instead as a built-in function, just like in Python2 (I never used it and the project's interpreter was Python 3.7). from __future__ import print_function would turn print into a function again but it's Python2 stuff.
I fixed it by creating a new virtual environment and setting up the interpreter again, so my question is: What causes this unexpected behavior?
I would like to avoid this when working on my most "serious" projects. Thanks all.