BUG: Validate drop_duplicates ignore_index argument for bool (#38277)

Author: phofl

doc/source/whatsnew/v1.2.0.rst

@@ -796,6 +796,7 @@ Reshaping
 - Bug in :func:`merge_ordered` couldn't handle list-like ``left_by`` or ``right_by`` (:issue:`35269`)
 - Bug in :func:`merge_ordered` returned wrong join result when length of ``left_by`` or ``right_by`` equals to the rows of ``left`` or ``right`` (:issue:`38166`)
 - Bug in :func:`merge_ordered` didn't raise when elements in ``left_by`` or ``right_by`` not exist in ``left`` columns or ``right`` columns (:issue:`38167`)
+- Bug in :func:`DataFrame.drop_duplicates` not validating bool dtype for ``ignore_index`` keyword (:issue:`38274`)
 
 Sparse
 ^^^^^^

pandas/core/frame.py

@@ -5273,6 +5273,7 @@ def drop_duplicates(
             return self.copy()
 
         inplace = validate_bool_kwarg(inplace, "inplace")
+        ignore_index = validate_bool_kwarg(ignore_index, "ignore_index")
         duplicated = self.duplicated(subset, keep=keep)
 
         result = self[-duplicated]

pandas/tests/frame/methods/test_drop_duplicates.py

@@ -459,3 +459,12 @@ def test_drop_duplicates_series_vs_dataframe(keep):
         dropped_frame = df[[column]].drop_duplicates(keep=keep)
         dropped_series = df[column].drop_duplicates(keep=keep)
         tm.assert_frame_equal(dropped_frame, dropped_series.to_frame())
+
+
+@pytest.mark.parametrize("arg", [[1], 1, "True", [], 0])
+def test_drop_duplicates_non_boolean_ignore_index(arg):
+    # GH#38274
+    df = DataFrame({"a": [1, 2, 1, 3]})
+    msg = '^For argument "ignore_index" expected type bool, received type .*.$'
+    with pytest.raises(ValueError, match=msg):
+        df.drop_duplicates(ignore_index=arg)