BUG: copy Index inputs to Series to preserve CoW reference tracking

Author: mroeschke

pandas/core/series.py

@@ -399,10 +399,14 @@ def __init__(
             self.name = name
             return
 
-        if isinstance(data, (ExtensionArray, np.ndarray)):
+        if isinstance(data, (ExtensionArray, np.ndarray, Index)):
             if copy is not False:
                 if dtype is None or astype_is_view(data.dtype, pandas_dtype(dtype)):
-                    data = data.copy()
+                    if isinstance(data, Index):
+                        # https://github.com/pandas-dev/pandas/issues/63306#issuecomment-3637458119
+                        data = data.copy(deep=True)
+                    else:
+                        data = data.copy()
         if copy is None:
             copy = False
 

pandas/tests/copy_view/test_constructors.py

@@ -107,12 +107,24 @@ def test_series_from_array_different_dtype(copy):
 def test_series_from_index(idx):
     ser = Series(idx)
     expected = idx.copy(deep=True)
-    assert np.shares_memory(get_array(ser), get_array(idx))
-    assert not ser._mgr._has_no_reference(0)
+    assert not np.shares_memory(get_array(ser), get_array(idx))
+    assert ser._mgr._has_no_reference(0)
     ser.iloc[0] = ser.iloc[1]
     tm.assert_index_equal(idx, expected)
 
 
+def test_series_from_temporary_index_readonly_data():
+    # GH 63306
+    arr = np.array([0, 1])
+    arr.flags.writeable = False
+    ser = Series(Index(arr))
+    assert not np.shares_memory(arr, get_array(ser))
+    assert ser._mgr._has_no_reference(0)
+    ser[[False, True]] = [0, 2]
+    expected = Series([0, 2])
+    tm.assert_series_equal(ser, expected)
+
+
 def test_series_from_index_different_dtypes():
     idx = Index([1, 2, 3], dtype="int64")
     ser = Series(idx, dtype="int32")