Remove option to use bare range in init

Author: topper-123

doc/source/whatsnew/v0.25.0.rst

@@ -100,6 +100,7 @@ Other Enhancements
 - :class:`DatetimeIndex` and :class:`TimedeltaIndex` now have a ``mean`` method (:issue:`24757`)
 - :meth:`DataFrame.describe` now formats integer percentiles without decimal point (:issue:`26660`)
 
+
 .. _whatsnew_0250.api_breaking:
 
 Backwards incompatible API changes

pandas/core/indexes/base.py

@@ -270,8 +270,10 @@ def __new__(cls, data=None, dtype=None, copy=False, name=None,
             data = data.to_numpy()
 
         # range
-        if isinstance(data, (RangeIndex, range)):
+        if isinstance(data, RangeIndex):
             return RangeIndex(start=data, copy=copy, dtype=dtype, name=name)
+        elif isinstance(data, range):
+            return RangeIndex.from_range(data, dtype=dtype, name=name)
 
         # categorical
         elif is_categorical_dtype(data) or is_categorical_dtype(dtype):

pandas/core/indexes/range.py

@@ -40,7 +40,7 @@ class RangeIndex(Int64Index):
 
     Parameters
     ----------
-    start : int (default: 0), range or RangeIndex instance
+    start : int (default: 0) or other RangeIndex instance
         If int and "stop" is not given, interpreted as "stop" instead.
     stop : int (default: 0)
     step : int (default: 1)
@@ -85,10 +85,9 @@ def __new__(cls, start=None, stop=None, step=None,
                 return cls._simple_new(range(start, stop, step), name=name)
 
         # RangeIndex, range
-        if isinstance(start, (RangeIndex, range)):
-            if isinstance(start, RangeIndex):
-                name = start.name if name is None else name
-                start = start._range
+        if isinstance(start, RangeIndex):
+            name = start.name if name is None else name
+            start = start._range
             return cls._simple_new(start, dtype=dtype, name=name)
 
         # validate the arguments

pandas/tests/indexes/test_range.py

@@ -94,9 +94,9 @@ def test_constructor_same(self):
 
     def test_constructor_range(self):
 
-        result = RangeIndex(range(1, 5, 2))
-        expected = RangeIndex(1, 5, 2)
-        tm.assert_index_equal(result, expected, exact=True)
+        msg = "Value needs to be a scalar value, was type <class 'range'>"
+        with pytest.raises(TypeError, match=msg):
+            result = RangeIndex(range(1, 5, 2))
 
         result = RangeIndex.from_range(range(1, 5, 2))
         expected = RangeIndex(1, 5, 2)