From f5e672934a55fe833252fae34b008084922d12c6 Mon Sep 17 00:00:00 2001
From: Brock <jbrockmendel@gmail.com>
Date: Fri, 9 Jul 2021 12:12:43 -0700
Subject: [PATCH] REGR: indexing with list subclass

---
 doc/source/whatsnew/v1.3.1.rst |  1 +
 pandas/core/common.py          |  6 +++++-
 pandas/tests/test_common.py    | 25 +++++++++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v1.3.1.rst b/doc/source/whatsnew/v1.3.1.rst
index 255747c3c5c6d..2c615618a98ef 100644
--- a/doc/source/whatsnew/v1.3.1.rst
+++ b/doc/source/whatsnew/v1.3.1.rst
@@ -18,6 +18,7 @@ Fixed regressions
 - :class:`DataFrame` constructed with with an older version of pandas could not be unpickled (:issue:`42345`)
 - Performance regression in constructing a :class:`DataFrame` from a dictionary of dictionaries (:issue:`42338`)
 - Fixed regression in :meth:`DataFrame.agg` dropping values when the DataFrame had an Extension Array dtype, a duplicate index, and ``axis=1`` (:issue:`42380`)
+- Fixed regression in indexing with a ``list`` subclass incorrectly raising ``TypeError`` (:issue:`42433`, :issue:42461`)
 -
 
 .. ---------------------------------------------------------------------------
diff --git a/pandas/core/common.py b/pandas/core/common.py
index 37674cdb34aec..b32614577393d 100644
--- a/pandas/core/common.py
+++ b/pandas/core/common.py
@@ -145,7 +145,11 @@ def is_bool_indexer(key: Any) -> bool:
             return True
     elif isinstance(key, list):
         # check if np.array(key).dtype would be bool
-        return len(key) > 0 and lib.is_bool_list(key)
+        if len(key) > 0:
+            if type(key) is not list:
+                # GH#42461 cython will raise TypeError if we pass a subclass
+                key = list(key)
+            return lib.is_bool_list(key)
 
     return False
 
diff --git a/pandas/tests/test_common.py b/pandas/tests/test_common.py
index a9b2176fba19a..5e9a53f32e0b7 100644
--- a/pandas/tests/test_common.py
+++ b/pandas/tests/test_common.py
@@ -162,3 +162,28 @@ def test_non_bool_array_with_na(self):
         # in particular, this should not raise
         arr = np.array(["A", "B", np.nan], dtype=object)
         assert not com.is_bool_indexer(arr)
+
+    def test_list_subclass(self):
+        # GH#42433
+
+        class MyList(list):
+            pass
+
+        val = MyList(["a"])
+
+        assert not com.is_bool_indexer(val)
+
+        val = MyList([True])
+        assert com.is_bool_indexer(val)
+
+    def test_frozenlist(self):
+        # GH#42461
+        data = {"col1": [1, 2], "col2": [3, 4]}
+        df = pd.DataFrame(data=data)
+
+        frozen = df.index.names[1:]
+        assert not com.is_bool_indexer(frozen)
+
+        result = df[frozen]
+        expected = df[[]]
+        tm.assert_frame_equal(result, expected)