Fix index locator cast bool key to float, closes #19087 (#22357)

Author: machenity

doc/source/whatsnew/v0.24.0.txt

@@ -656,6 +656,7 @@ Indexing
 - Fixed ``DataFrame[np.nan]`` when columns are non-unique (:issue:`21428`)
 - Bug when indexing :class:`DatetimeIndex` with nanosecond resolution dates and timezones (:issue:`11679`)
 - Bug where indexing with a Numpy array containing negative values would mutate the indexer (:issue:`21867`)
+- ``Float64Index.get_loc`` now raises ``KeyError`` when boolean key passed. (:issue:`19087`)
 
 Missing
 ^^^^^^^

pandas/core/indexes/numeric.py

@@ -403,7 +403,7 @@ def __contains__(self, other):
     @Appender(_index_shared_docs['get_loc'])
     def get_loc(self, key, method=None, tolerance=None):
         try:
-            if np.all(np.isnan(key)):
+            if np.all(np.isnan(key)) or is_bool(key):
                 nan_idxs = self._nan_idxs
                 try:
                     return nan_idxs.item()

pandas/tests/indexes/test_numeric.py

@@ -289,6 +289,8 @@ def test_get_loc(self):
         pytest.raises(KeyError, idx.get_loc, 1.5)
         pytest.raises(KeyError, idx.get_loc, 1.5, method='pad',
                       tolerance=0.1)
+        pytest.raises(KeyError, idx.get_loc, True)
+        pytest.raises(KeyError, idx.get_loc, False)
 
         with tm.assert_raises_regex(ValueError, 'must be numeric'):
             idx.get_loc(1.4, method='nearest', tolerance='foo')