scikit-learn__scikit-learn-25570

ColumnTransformer with pandas output can't handle transformers with no features

Verdict: disputed: one of the two checks found quoted evidence (not counted as a flag).

It seems steps with 0 features are not fitted, hence don't appear in `self._iter(fitted=True)` (_column_transformer.py l.856) and hence break the input to the `_add_prefix_for_feature_names_out` function (l.859).

Disputed: one of the two checks found a pointer to the fix, the other found nothing. Not counted as a flag; the quote is on the task page.

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