`round` doesn't convert the magnitude of a quantity to `int`

[Kodiologist]

>>> import pint; U = pint.UnitRegistry()
>>> round(1.1), type(round(1.1))
(1, <class 'int'>)
>>> round(1.1 * U.kg), type(round(1.1 * U.kg).magnitude)
(<Quantity(1.0, 'kilogram')>, <class 'float'>)

I'm not sure if this is a bug, but it certainly surprised me.

[jules-ch]

Seems to come from this line

pint/pint/facets/plain/quantity.py

Line 1291 in c70c076

def __round__(self, ndigits: int | None = 0) -> PlainQuantity[MagnitudeT]:

Want to open a PR for this ?

[jules-ch]

Might be more complicated than just type hinting haha, I will try to see whats going on

[Kodiologist]

I haven't used type hints much myself. That code sure looks like it should produce an int, if the built-in round is being called.

[jules-ch]

Those lines should be like this:

    def __round__(self, ndigits: int | None = None) -> PlainQuantity[int]:
        return self.__class__(round(self._magnitude, ndigits), self._units)

[jules-ch]

Per the docs :

round(number[, ndigits])
Return number rounded to ndigits precision after the decimal point. If ndigits is omitted or is None, it returns the nearest integer to its input.

It defaulted to 0 here