CoW: Add warning for mask, where and clip with inplace (#56067)

Co-authored-by: Joris Van den Bossche <[email protected]>

Author: phofl

pandas/core/generic.py

@@ -8903,6 +8903,18 @@ def clip(
                         ChainedAssignmentError,
                         stacklevel=2,
                     )
+            elif not PYPY and not using_copy_on_write():
+                ctr = sys.getrefcount(self)
+                ref_count = REF_COUNT
+                if isinstance(self, ABCSeries) and hasattr(self, "_cacher"):
+                    # see https://github.com/pandas-dev/pandas/pull/56060#discussion_r1399245221
+                    ref_count += 1
+                if ctr <= ref_count:
+                    warnings.warn(
+                        _chained_assignment_warning_method_msg,
+                        FutureWarning,
+                        stacklevel=2,
+                    )
 
         axis = nv.validate_clip_with_axis(axis, (), kwargs)
         if axis is not None:
@@ -10803,6 +10815,19 @@ def where(
                         ChainedAssignmentError,
                         stacklevel=2,
                     )
+            elif not PYPY and not using_copy_on_write():
+                ctr = sys.getrefcount(self)
+                ref_count = REF_COUNT
+                if isinstance(self, ABCSeries) and hasattr(self, "_cacher"):
+                    # see https://github.com/pandas-dev/pandas/pull/56060#discussion_r1399245221
+                    ref_count += 1
+                if ctr <= ref_count:
+                    warnings.warn(
+                        _chained_assignment_warning_method_msg,
+                        FutureWarning,
+                        stacklevel=2,
+                    )
+
         other = common.apply_if_callable(other, self)
         return self._where(cond, other, inplace, axis, level)
 
@@ -10869,14 +10894,27 @@ def mask(
                         ChainedAssignmentError,
                         stacklevel=2,
                     )
+            elif not PYPY and not using_copy_on_write():
+                ctr = sys.getrefcount(self)
+                ref_count = REF_COUNT
+                if isinstance(self, ABCSeries) and hasattr(self, "_cacher"):
+                    # see https://github.com/pandas-dev/pandas/pull/56060#discussion_r1399245221
+                    ref_count += 1
+                if ctr <= ref_count:
+                    warnings.warn(
+                        _chained_assignment_warning_method_msg,
+                        FutureWarning,
+                        stacklevel=2,
+                    )
 
         cond = common.apply_if_callable(cond, self)
+        other = common.apply_if_callable(other, self)
 
         # see gh-21891
         if not hasattr(cond, "__invert__"):
             cond = np.array(cond)
 
-        return self.where(
+        return self._where(
             ~cond,
             other=other,
             inplace=inplace,

pandas/tests/copy_view/test_clip.py

@@ -1,6 +1,9 @@
 import numpy as np
 
-from pandas import DataFrame
+from pandas import (
+    DataFrame,
+    option_context,
+)
 import pandas._testing as tm
 from pandas.tests.copy_view.util import get_array
 
@@ -81,3 +84,14 @@ def test_clip_chained_inplace(using_copy_on_write):
         with tm.raises_chained_assignment_error():
             df[["a"]].clip(1, 2, inplace=True)
         tm.assert_frame_equal(df, df_orig)
+    else:
+        with tm.assert_produces_warning(FutureWarning, match="inplace method"):
+            df["a"].clip(1, 2, inplace=True)
+
+        with tm.assert_produces_warning(FutureWarning, match="inplace method"):
+            with option_context("mode.chained_assignment", None):
+                df[["a"]].clip(1, 2, inplace=True)
+
+        with tm.assert_produces_warning(FutureWarning, match="inplace method"):
+            with option_context("mode.chained_assignment", None):
+                df[df["a"] > 1].clip(1, 2, inplace=True)

pandas/tests/copy_view/test_methods.py

@@ -1551,6 +1551,17 @@ def test_chained_where_mask(using_copy_on_write, func):
         with tm.raises_chained_assignment_error():
             getattr(df[["a"]], func)(df["a"] > 2, 5, inplace=True)
         tm.assert_frame_equal(df, df_orig)
+    else:
+        with tm.assert_produces_warning(FutureWarning, match="inplace method"):
+            getattr(df["a"], func)(df["a"] > 2, 5, inplace=True)
+
+        with tm.assert_produces_warning(FutureWarning, match="inplace method"):
+            with option_context("mode.chained_assignment", None):
+                getattr(df[["a"]], func)(df["a"] > 2, 5, inplace=True)
+
+        with tm.assert_produces_warning(FutureWarning, match="inplace method"):
+            with option_context("mode.chained_assignment", None):
+                getattr(df[df["a"] > 1], func)(df["a"] > 2, 5, inplace=True)
 
 
 def test_asfreq_noop(using_copy_on_write):