Backport PR #42633: Fixed regression for SettingWithCopyWarning showing incorrect stacklevel (#42678)

Co-authored-by: Patrick Hoefler <[email protected]>

Author: meeseeksmachine

doc/source/whatsnew/v1.3.1.rst

@@ -25,6 +25,7 @@ Fixed regressions
 - Fixed regression in :meth:`DataFrame.isin` and :meth:`Series.isin` raising ``TypeError`` with nullable data containing at least one missing value (:issue:`42405`)
 - Regression in :func:`concat` between objects with bool dtype and integer dtype casting to object instead of to integer (:issue:`42092`)
 - Bug in :class:`Series` constructor not accepting a ``dask.Array`` (:issue:`38645`)
+- Fixed regression for ``SettingWithCopyWarning`` displaying incorrect stacklevel (:issue:`42570`)
 - Fixed regression in :func:`to_datetime` returning pd.NaT for inputs that produce duplicated values, when ``cache=True`` (:issue:`42259`)
 
 

pandas/core/frame.py

@@ -3754,7 +3754,7 @@ def _set_item_mgr(self, key, value: ArrayLike) -> None:
         # try to set first as we want an invalid
         # value exception to occur first
         if len(self):
-            self._check_setitem_copy()
+            self._check_setitem_copy(stacklevel=5)
 
     def _iset_item(self, loc: int, value) -> None:
         arraylike = self._sanitize_column(value)

pandas/tests/indexing/test_chaining_and_caching.py

@@ -435,6 +435,16 @@ def test_detect_chained_assignment_warnings_filter_and_dupe_cols(self):
             )
             tm.assert_frame_equal(df, expected)
 
+    @pytest.mark.parametrize("rhs", [3, DataFrame({0: [1, 2, 3, 4]})])
+    def test_detect_chained_assignment_warning_stacklevel(self, rhs):
+        # GH#42570
+        df = DataFrame(np.arange(25).reshape(5, 5))
+        chained = df.loc[:3]
+        with option_context("chained_assignment", "warn"):
+            with tm.assert_produces_warning(com.SettingWithCopyWarning) as t:
+                chained[2] = rhs
+                assert t[0].filename == __file__
+
     # TODO(ArrayManager) fast_xs with array-like scalars is not yet working
     @td.skip_array_manager_not_yet_implemented
     def test_chained_getitem_with_lists(self):