REGR: fix inplace operations for EAs with non-EA arg

doc/source/whatsnew/v1.1.5.rst

@@ -17,7 +17,7 @@ Fixed regressions
 - Regression in addition of a timedelta-like scalar to a :class:`DatetimeIndex` raising incorrectly (:issue:`37295`)
 - Fixed regression in :meth:`Series.groupby` raising when the :class:`Index` of the :class:`Series` had a tuple as its name (:issue:`37755`)
 - Fixed regression in :meth:`DataFrame.loc` and :meth:`Series.loc` for ``__setitem__`` when one-dimensional tuple was given to select from :class:`MultiIndex` (:issue:`37711`)
--
+- Fixed regression in inplace operations on :class:`Series` with ``ExtensionDtype`` with NumPy dtyped operand (:issue:`37910`)
 
 .. ---------------------------------------------------------------------------
 

pandas/core/generic.py

@@ -70,6 +70,7 @@
     is_datetime64_any_dtype,
     is_datetime64tz_dtype,
     is_dict_like,
+    is_dtype_equal,
     is_extension_array_dtype,
     is_float,
     is_list_like,
@@ -11266,7 +11267,11 @@ def _inplace_method(self, other, op):
         """
         result = op(self, other)
 
-        if self.ndim == 1 and result._indexed_same(self) and result.dtype == self.dtype:
+        if (
+            self.ndim == 1
+            and result._indexed_same(self)
+            and is_dtype_equal(result.dtype, self.dtype)
+        ):
             # GH#36498 this inplace op can _actually_ be inplace.
             self._values[:] = result._values
             return self

pandas/tests/series/test_arithmetic.py

@@ -832,6 +832,40 @@ def test_scalarop_preserve_name(self, datetime_series):
         assert result.name == datetime_series.name
 
 
+class TestInplaceOperations:
+    @pytest.mark.parametrize(
+        "dtype1, dtype2, dtype_expected, dtype_mul",
+        (
+            ("Int64", "Int64", "Int64", "Int64"),
+            ("float", "float", "float", "float"),
+            ("Int64", "float", "float", "float"),
+            pytest.param(
+                "Int64",
+                "Float64",
+                "Float64",
+                "Float64",
+                marks=pytest.mark.xfail(reason="Not implemented yet"),
+            ),
+        ),
+    )
+    def test_series_inplace_ops(self, dtype1, dtype2, dtype_expected, dtype_mul):
+        # GH 37910
+
+        ser1 = Series([1], dtype=dtype1)
+        ser2 = Series([2], dtype=dtype2)
+        ser1 += ser2
+        expected = Series([3], dtype=dtype_expected)
+        tm.assert_series_equal(ser1, expected)
+
+        ser1 -= ser2
+        expected = Series([1], dtype=dtype_expected)
+        tm.assert_series_equal(ser1, expected)
+
+        ser1 *= ser2
+        expected = Series([2], dtype=dtype_mul)
+        tm.assert_series_equal(ser1, expected)
+
+
 def test_none_comparison(series_with_simple_index):
     series = series_with_simple_index
     if isinstance(series.index, IntervalIndex):