[BUG] Validate dtype when Int64Index, UInt64Index, or Float64Index are cons…

doc/source/whatsnew/v1.0.0.rst

@@ -336,6 +336,7 @@ Numeric
 - Bug in :class:`DataFrame` logical operations (`&`, `|`, `^`) not matching :class:`Series` behavior by filling NA values (:issue:`28741`)
 - Bug in :meth:`DataFrame.interpolate` where specifying axis by name references variable before it is assigned (:issue:`29142`)
 - Improved error message when using `frac` > 1 and `replace` = False (:issue:`27451`)
+- Bug in numeric indexes resulted in it being possible to instantiate an :class:`Int64Index`, :class:`UInt64Index`, or :class:`Float64Index` with an invalid dtype (e.g. datetime-like) (:issue:`29539`)
 -
 
 Conversion

pandas/core/indexes/base.py

@@ -380,7 +380,7 @@ def __new__(
                             pass
 
                         # Return an actual float index.
-                        return Float64Index(data, copy=copy, dtype=dtype, name=name)
+                        return Float64Index(data, copy=copy, name=name)
 
                     elif inferred == "string":
                         pass

pandas/core/indexes/numeric.py

@@ -15,6 +15,8 @@
     is_float_dtype,
     is_integer_dtype,
     is_scalar,
+    is_signed_integer_dtype,
+    is_unsigned_integer_dtype,
     needs_i8_conversion,
     pandas_dtype,
 )
@@ -26,6 +28,7 @@
 )
 from pandas.core.dtypes.missing import isna
 
+from pandas._typing import Dtype
 from pandas.core import algorithms
 import pandas.core.common as com
 from pandas.core.indexes.base import Index, InvalidIndexError, _index_shared_docs
@@ -45,7 +48,7 @@ class NumericIndex(Index):
     _is_numeric_dtype = True
 
     def __new__(cls, data=None, dtype=None, copy=False, name=None, fastpath=None):
-
+        cls._validate_dtype(dtype)
         if fastpath is not None:
             warnings.warn(
                 "The 'fastpath' keyword is deprecated, and will be "
@@ -72,6 +75,22 @@ def __new__(cls, data=None, dtype=None, copy=False, name=None, fastpath=None):
             name = data.name
         return cls._simple_new(subarr, name=name)
 
+    @classmethod
+    def _validate_dtype(cls, dtype: Dtype) -> None:
+        if dtype is None:
+            return
+        validation_metadata = {
+            "int64index": (is_signed_integer_dtype, "signed integer"),
+            "uint64index": (is_unsigned_integer_dtype, "unsigned integer"),
+            "float64index": (is_float_dtype, "float"),
+            "rangeindex": (is_signed_integer_dtype, "signed integer"),
+        }
+
+        validation_func, expected = validation_metadata[cls._typ]
+        if not validation_func(dtype):
+            msg = f"Incorrect `dtype` passed: expected {expected}, received {dtype}"
+            raise ValueError(msg)
+
     @Appender(_index_shared_docs["_maybe_cast_slice_bound"])
     def _maybe_cast_slice_bound(self, label, side, kind):
         assert kind in ["ix", "loc", "getitem", None]

pandas/core/indexes/range.py

@@ -14,7 +14,6 @@
 from pandas.core.dtypes.common import (
     ensure_platform_int,
     ensure_python_int,
-    is_int64_dtype,
     is_integer,
     is_integer_dtype,
     is_list_like,
@@ -167,12 +166,6 @@ def _simple_new(cls, values, name=None, dtype=None, **kwargs):
 
     # --------------------------------------------------------------------
 
-    @staticmethod
-    def _validate_dtype(dtype):
-        """ require dtype to be None or int64 """
-        if not (dtype is None or is_int64_dtype(dtype)):
-            raise TypeError("Invalid to pass a non-int64 dtype to RangeIndex")
-
     @cache_readonly
     def _constructor(self):
         """ return the class to use for construction """

pandas/tests/indexes/test_numeric.py

@@ -167,6 +167,23 @@ def test_constructor(self):
         result = Index(np.array([np.nan]))
         assert pd.isna(result.values).all()
 
+    @pytest.mark.parametrize(
+        "index, dtype",
+        [
+            (pd.Int64Index, "float64"),
+            (pd.UInt64Index, "categorical"),
+            (pd.Float64Index, "datetime64"),
+            (pd.RangeIndex, "float64"),
+        ],
+    )
+    def test_invalid_dtype(self, index, dtype):
+        # GH 29539
+        with pytest.raises(
+            ValueError,
+            match=rf"Incorrect `dtype` passed: expected \w+(?: \w+)?, received {dtype}",
+        ):
+            index([1, 2, 3], dtype=dtype)
+
     def test_constructor_invalid(self):
 
         # invalid

pandas/tests/indexes/test_range.py

@@ -110,7 +110,7 @@ def test_constructor_same(self):
         result = RangeIndex(index)
         tm.assert_index_equal(result, index, exact=True)
 
-        with pytest.raises(TypeError):
+        with pytest.raises(ValueError):
             RangeIndex(index, dtype="float64")
 
     def test_constructor_range(self):
@@ -140,7 +140,7 @@ def test_constructor_range(self):
         expected = RangeIndex(1, 5, 2)
         tm.assert_index_equal(result, expected, exact=True)
 
-        with pytest.raises(TypeError):
+        with pytest.raises(ValueError):
             Index(range(1, 5, 2), dtype="float64")
         msg = r"^from_range\(\) got an unexpected keyword argument"
         with pytest.raises(TypeError, match=msg):
@@ -178,7 +178,7 @@ def test_constructor_corner(self):
             RangeIndex(1.1, 10.2, 1.3)
 
         # invalid passed type
-        with pytest.raises(TypeError):
+        with pytest.raises(ValueError):
             RangeIndex(1, 5, dtype="float64")
 
     @pytest.mark.parametrize(

pandas/tests/series/indexing/test_numeric.py

@@ -86,8 +86,7 @@ def test_get():
                 1764.0,
                 1849.0,
                 1936.0,
-            ],
-            dtype="object",
+            ]
         ),
     )