mypy doesn't seem to be able to recognize dashed-options as incorrect within the context of a config file.

For example, suppose we have the following files nothing.py and mypy.ini

def nothing():
    pass

[mypy]
X = True

When X is:

• disallow_untyped_defs
  • Correctly reports nothing.py:1: error: Function is missing a type annotation
• disallow_untyped_defs1
  • Correctly reports: mypy.ini: [mypy]: Unrecognized option: disallow_untyped_defs1 = True
• disallow-untyped-defs
  • Doesn't tell me I'm missing a type annotation, nor that the option is incorrect. No errors at all!

Python 3.6.4 and mypy 0.570 were used.