BUG: ensure we still honor copy=True in Series constructor in all cases #63342
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jorisvandenbossche
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Series
mroeschke
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Dec 12, 2025
| if copy is not False: | ||
| if dtype is None or astype_is_view(data.dtype, pandas_dtype(dtype)): | ||
| data = data.copy() | ||
| copy = False |
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To avoid another copy later
| Pandas4Warning, | ||
| stacklevel=2, | ||
| ) | ||
| allow_mgr = True |
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To avoid raising this warning a second time below in some specific corner case
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| copy = False | ||
| data = data._mgr | ||
| if data._has_no_reference(0): | ||
| copy = False |
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The reindex could in theory return a shallow copy instead of full copy (if the passed index is identical to data's index), so the change here is to ensure that we only override copy to False if that did not happen (i.e. when there is no reference between the original and reindexed data).
That is to ensure that if the user specified copy=True, it will actually get a copy, and not a shallow copy, even in this case of reindexing.
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Expanding the
Series(..)constructor tests to cover all cases for copy=True vs False vs default None, and ensure we still honorcopy=Truewhen passing a Series or Index.Triggered by checking the exact behaviour to describe that in the docstring for #63341