Fix related issue

pandas/core/indexing.py

@@ -8,6 +8,8 @@
 
 from pandas._libs.indexing import NDFrameIndexerBase
 from pandas._libs.lib import item_from_zerodim
+
+from pandas.core.dtypes.cast import infer_dtype_from_scalar
 from pandas.errors import AbstractMethodError, InvalidIndexError
 from pandas.util._decorators import doc
 
@@ -1552,6 +1554,9 @@ def _setitem_with_indexer(self, indexer, value):
                 blk = self.obj._mgr.blocks[0]
                 take_split_path = not blk._can_hold_element(val)
                 if not take_split_path:
+                    if is_scalar(value):
+                        dtype = infer_dtype_from_scalar(value)
+                        take_split_path = not is_dtype_equal(dtype, blk.dtype)
                     if isinstance(value, ABCSeries):
                         take_split_path = not (is_dtype_equal(value.dtype, blk.dtype))
                     elif isinstance(value, ABCDataFrame):

pandas/tests/frame/indexing/test_setitem.py

@@ -333,6 +333,18 @@ def test_setitem_conversion_to_datetime(self):
         )
         tm.assert_frame_equal(df, expected)
 
+    def test_setitem_scalar_dtype_change(self):
+        # GH#27583
+        df = DataFrame({"a": [0.0], "b": [0.0]})
+        df[["a", "b"]] = 0
+        expected = DataFrame({"a": [0], "b": [0]})
+        tm.assert_frame_equal(df, expected)
+
+        df = DataFrame({"a": [0.0], "b": [0.0]})
+        df["b"] = 0
+        expected = DataFrame({"a": [0.0], "b": [0]})
+        tm.assert_frame_equal(df, expected)
+
 
 class TestDataFrameSetItemSlicing:
     def test_setitem_slice_position(self):