[issue41907] Regression in IntFlag behaviour in f-string

[Dominic Davis-Foster]

Dominic Davis-Foster <dom1310df at googlemail.com> added the comment:

I believe the regression is due to GH-14545 which "fixed" bpo-37479. The news entry states:

"When `Enum.__str__` is overridden in a derived class, the override will be used by `Enum.__format__` regardless of whether mixin classes are present."

.

The change is in the __format__ method of Enum. It now checks if type(self).__str__ != Enum.__str__ and if True calls str(self). Because Flag defines its own __str__ method, the expression evaluates to True. I do not think this is the indented behaviour.

In 3.8.5 str(self) was only called if _member_type_ is object.

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nosy: +dom1310df

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<https://bugs.python.org/issue41907>
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