BUG: setitem into complex64 overflow

doc/source/whatsnew/v1.5.0.rst

@@ -154,7 +154,7 @@ Indexing
 ^^^^^^^^
 - Bug in :meth:`DataFrame.iloc` where indexing a single row on a :class:`DataFrame` with a single ExtensionDtype column gave a copy instead of a view on the underlying data (:issue:`45241`)
 - Bug in :meth:`Series.__setitem__` with a non-integer :class:`Index` when using an integer key to set a value that cannot be set inplace where a ``ValueError`` was raised insead of casting to a common dtype (:issue:`45070`)
-- Bug when setting an integer too large for a :class:`Series` dtype failing to coerce to a common type (:issue:`26049`)
+- Bug when setting a value too large for a :class:`Series` dtype failing to coerce to a common type (:issue:`26049`, :issue:`32878`)
 -
 
 Missing

pandas/core/dtypes/cast.py

@@ -1931,12 +1931,21 @@ def np_can_hold_element(dtype: np.dtype, element: Any) -> Any:
         raise ValueError
 
     elif dtype.kind == "c":
+        if lib.is_integer(element) or lib.is_complex(element) or lib.is_float(element):
+            if np.isnan(element):
+                # see test_where_complex GH#6345
+                return dtype.type(element)
+
+            casted = dtype.type(element)
+            if casted == element:
+                return casted
+            # otherwise e.g. overflow see test_32878_complex_itemsize
+            raise ValueError
+
         if tipo is not None:
             if tipo.kind in ["c", "f", "i", "u"]:
                 return element
             raise ValueError
-        if lib.is_integer(element) or lib.is_complex(element) or lib.is_float(element):
-            return element
         raise ValueError
 
     elif dtype.kind == "b":

pandas/tests/series/indexing/test_setitem.py

@@ -1373,6 +1373,19 @@ def test_32878_int_itemsize():
     tm.assert_series_equal(ser, expected)
 
 
+def test_32878_complex_itemsize():
+    arr = np.arange(5).astype("c8")
+    ser = Series(arr)
+    val = np.finfo(np.float64).max
+    val = val.astype("c16")
+
+    # GH#32878 used to coerce val to inf+0.000000e+00j
+    ser[0] = val
+    assert ser[0] == val
+    expected = Series([val, 1, 2, 3, 4], dtype="c16")
+    tm.assert_series_equal(ser, expected)
+
+
 def test_37692(indexer_al):
     # GH#37692
     ser = Series([1, 2, 3], index=["a", "b", "c"])
@@ -1424,21 +1437,6 @@ def test_setitem_positional_float_into_int_coerces():
     tm.assert_series_equal(ser, expected)
 
 
-@pytest.mark.xfail(reason="Fails to upcast")
-def test_32878_complex_itemsize():
-    # TODO: when fixed, put adjacent to test_32878_int_itemsize
-    arr = np.arange(5).astype("c8")
-    ser = Series(arr)
-    val = np.finfo(np.float64).max
-    val = val.astype("c16")
-
-    # GH#32878 used to coerce val to inf+0.000000e+00j
-    ser[0] = val
-    assert ser[0] == val
-    expected = Series([val, 1, 2, 3, 4], dtype="c16")
-    tm.assert_series_equal(ser, expected)
-
-
 def test_setitem_int_as_positional_fallback_deprecation():
     # GH#42215 deprecated falling back to positional on __setitem__ with an
     #  int not contained in the index