From 750f27b0a919365ebe3906dcd0102a4304e5c6ff Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <61934744+phofl@users.noreply.github.com>
Date: Wed, 7 Sep 2022 09:12:36 +0200
Subject: [PATCH] Backport PR #48411: REGR: get_loc for ExtensionEngine not
 returning bool indexer for na

---
 pandas/_libs/index.pyx                |  2 +-
 pandas/tests/indexes/test_indexing.py | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/pandas/_libs/index.pyx b/pandas/_libs/index.pyx
index 0cf7c4d45c634..617760c2981c4 100644
--- a/pandas/_libs/index.pyx
+++ b/pandas/_libs/index.pyx
@@ -1061,7 +1061,7 @@ cdef class ExtensionEngine(SharedEngine):
 
     cdef ndarray _get_bool_indexer(self, val):
         if checknull(val):
-            return self.values.isna().view("uint8")
+            return self.values.isna()
 
         try:
             return self.values == val
diff --git a/pandas/tests/indexes/test_indexing.py b/pandas/tests/indexes/test_indexing.py
index 739039241a31d..ab934df992d61 100644
--- a/pandas/tests/indexes/test_indexing.py
+++ b/pandas/tests/indexes/test_indexing.py
@@ -20,6 +20,7 @@
 from pandas.errors import InvalidIndexError
 
 from pandas import (
+    NA,
     DatetimeIndex,
     Index,
     IntervalIndex,
@@ -221,6 +222,13 @@ def test_get_loc_generator(self, index):
             # MultiIndex specifically checks for generator; others for scalar
             index.get_loc(x for x in range(5))
 
+    def test_get_loc_masked_duplicated_na(self):
+        # GH#48411
+        idx = Index([1, 2, NA, NA], dtype="Int64")
+        result = idx.get_loc(NA)
+        expected = np.array([False, False, True, True])
+        tm.assert_numpy_array_equal(result, expected)
+
 
 class TestGetIndexer:
     def test_get_indexer_base(self, index):
@@ -253,6 +261,13 @@ def test_get_indexer_consistency(self, index):
         assert isinstance(indexer, np.ndarray)
         assert indexer.dtype == np.intp
 
+    def test_get_indexer_masked_duplicated_na(self):
+        # GH#48411
+        idx = Index([1, 2, NA, NA], dtype="Int64")
+        result = idx.get_indexer_for(Index([1, NA], dtype="Int64"))
+        expected = np.array([0, 2, 3], dtype=result.dtype)
+        tm.assert_numpy_array_equal(result, expected)
+
 
 class TestConvertSliceIndexer:
     def test_convert_almost_null_slice(self, index):