According to PEP 526, this is not allowed:

In addition, one cannot annotate variables used in a for or with statement; they can be annotated ahead of time, in a similar manner to tuple unpacking

Annotate it before the loop:

i: int
for i in range(5):
    pass

PyCharm 2018.1 and up now recognizes the type of the variable inside the loop. This was not supported in older PyCharm versions.


I don't know if this solution is PEP-compatible or just a feature of PyCharm, but I made it work like this:

for i in range(5): #type: int
  pass

and I'm using Pycharm Community Edition 2016.2.1