Incompatibility with Flask <2.0 due to flask.typing import

[apgiorgi]

The functions-framework package (as of version 3.5.0) is using flask.typing, which was introduced in Flask 2.0.0. However, the setup.py file allows Flask versions from 1.0 to 4.0. This causes runtime errors when using functions-framework with Flask versions before 2.0.0.

Error Message

CopyTraceback (most recent call last):
File "/layers/google.python.pip/pip/bin/functions-framework", line 5, in <module>
    from functions_framework._cli import *cli
File "/layers/google.python.pip/pip/lib/python3.7/site-packages/functions_framework/__init__.py", line 57, in <module>
    HTTPFunction = Callable[[flask.Request], flask.typing.ResponseReturnValue]
AttributeError: module 'flask' has no attribute 'typing'

Proposed Solution

Requirements should be updated to Flask 2.0.0 or later.