Eventually upgrade mypy #1124
Description
In #1119 @erichulburd noticed that make typecheck was failing with mypy 0.750 and so pinned our mypy dependency to 0.740 as a workaround.
The type errors on mypy 0.750 stem from the definition of ExpressionDesignator in quilatom.py, which is a nested Union type like so:
ExpressionValueDesignator = Union[int, float, complex]
ExpressionDesignator = Union['Expression', ExpressionValueDesignator]Long story short, mypy 0.750 doesn't like the nested ExpressionValueDesignator.
As a workaround, flattening the Union like so resolves the issue:
ExpressionValueDesignator = Union[int, float, complex]
-ExpressionDesignator = Union['Expression', ExpressionValueDesignator]
+ExpressionDesignator = Union['Expression', int, float, complex]I've opened a mypy issue upstream.
For now we should just keep mypy pinned to 0.740, but when/if the above mypy issue is addressed, we me might consider upgrading, or else apply the above patch if the mypy issue is resolved as "wont fix".