From 9ee4039f68512861612ae29b6644a1a33a937514 Mon Sep 17 00:00:00 2001
From: jbrockmendel <jbrockmendel@gmail.com>
Date: Mon, 21 Jun 2021 07:26:43 -0700
Subject: [PATCH] DEPR: Index.is_type_compatible (#42113)

---
 doc/source/whatsnew/v1.4.0.rst         |  2 +-
 pandas/core/indexes/base.py            |  6 ++++++
 pandas/core/indexes/datetimelike.py    |  7 +++++++
 pandas/core/indexes/multi.py           | 16 ++++++++++------
 pandas/tests/indexes/test_any_index.py |  7 +++++++
 5 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/doc/source/whatsnew/v1.4.0.rst b/doc/source/whatsnew/v1.4.0.rst
index 9859f12a34621..f992d6aa09ead 100644
--- a/doc/source/whatsnew/v1.4.0.rst
+++ b/doc/source/whatsnew/v1.4.0.rst
@@ -96,7 +96,7 @@ Other API changes
 
 Deprecations
 ~~~~~~~~~~~~
--
+- Deprecated :meth:`Index.is_type_compatible` (:issue:`42113`)
 -
 
 .. ---------------------------------------------------------------------------
diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 88fded29810ff..b092bd6666fc0 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -4489,6 +4489,12 @@ def is_type_compatible(self, kind: str_t) -> bool:
         """
         Whether the index type is compatible with the provided type.
         """
+        warnings.warn(
+            "Index.is_type_compatible is deprecated and will be removed in a "
+            "future version",
+            FutureWarning,
+            stacklevel=2,
+        )
         return kind == self.inferred_type
 
     def __contains__(self, key: Any) -> bool:
diff --git a/pandas/core/indexes/datetimelike.py b/pandas/core/indexes/datetimelike.py
index 7143b275214ee..417d517081863 100644
--- a/pandas/core/indexes/datetimelike.py
+++ b/pandas/core/indexes/datetimelike.py
@@ -11,6 +11,7 @@
     TypeVar,
     cast,
 )
+import warnings
 
 import numpy as np
 
@@ -634,6 +635,12 @@ def _has_complex_internals(self) -> bool:
         return False
 
     def is_type_compatible(self, kind: str) -> bool:
+        warnings.warn(
+            f"{type(self).__name__}.is_type_compatible is deprecated and will be "
+            "removed in a future version",
+            FutureWarning,
+            stacklevel=2,
+        )
         return kind in self._data._infer_matches
 
     # --------------------------------------------------------------------
diff --git a/pandas/core/indexes/multi.py b/pandas/core/indexes/multi.py
index f1f418453c68b..7b70a26155358 100644
--- a/pandas/core/indexes/multi.py
+++ b/pandas/core/indexes/multi.py
@@ -2792,15 +2792,19 @@ def _partial_tup_index(self, tup: tuple, side="left"):
         n = len(tup)
         start, end = 0, len(self)
         zipped = zip(tup, self.levels, self.codes)
-        for k, (lab, lev, labs) in enumerate(zipped):
-            section = labs[start:end]
+        for k, (lab, lev, level_codes) in enumerate(zipped):
+            section = level_codes[start:end]
 
             if lab not in lev and not isna(lab):
-                if not lev.is_type_compatible(lib.infer_dtype([lab], skipna=False)):
-                    raise TypeError(f"Level type mismatch: {lab}")
-
                 # short circuit
-                loc = lev.searchsorted(lab, side=side)
+                try:
+                    loc = lev.searchsorted(lab, side=side)
+                except TypeError as err:
+                    # non-comparable e.g. test_slice_locs_with_type_mismatch
+                    raise TypeError(f"Level type mismatch: {lab}") from err
+                if not is_integer(loc):
+                    # non-comparable level, e.g. test_groupby_example
+                    raise TypeError(f"Level type mismatch: {lab}")
                 if side == "right" and loc >= 0:
                     loc -= 1
                 return start + section.searchsorted(loc, side=side)
diff --git a/pandas/tests/indexes/test_any_index.py b/pandas/tests/indexes/test_any_index.py
index 60fa8f1a0c083..f7dcaa628228b 100644
--- a/pandas/tests/indexes/test_any_index.py
+++ b/pandas/tests/indexes/test_any_index.py
@@ -66,6 +66,13 @@ def test_ravel_deprecation(index):
         index.ravel()
 
 
+def test_is_type_compatible_deprecation(index):
+    # GH#42113
+    msg = "is_type_compatible is deprecated"
+    with tm.assert_produces_warning(FutureWarning, match=msg):
+        index.is_type_compatible(index.inferred_type)
+
+
 class TestConversion:
     def test_to_series(self, index):
         # assert that we are creating a copy of the index