From 28510eae293f6051862a28969429591927757834 Mon Sep 17 00:00:00 2001
From: MarcoGorelli <>
Date: Tue, 28 Feb 2023 10:18:45 +0000
Subject: [PATCH 1/3] start enabling TCH

---
 pandas/_config/config.py               | 11 +++++---
 pandas/_testing/__init__.py            | 11 ++++----
 pandas/_testing/_io.py                 |  9 ++++---
 pandas/_testing/_random.py             |  5 ++--
 pandas/_testing/compat.py              |  5 +++-
 pandas/_testing/contexts.py            | 13 ++++++----
 pandas/_typing.py                      | 16 ++++++------
 pandas/compat/__init__.py              |  5 +++-
 pandas/compat/_optional.py             |  5 +++-
 pandas/compat/numpy/function.py        | 11 +++++---
 pandas/core/_numba/executor.py         |  4 ++-
 pandas/core/_numba/kernels/shared.py   |  6 ++++-
 pandas/core/computation/expressions.py |  5 +++-
 pandas/core/computation/pytables.py    |  9 +++++--
 pandas/core/indexing.py                |  9 ++++---
 pandas/core/interchange/utils.py       |  5 ++--
 pandas/core/sample.py                  |  3 ++-
 pyproject.toml                         | 36 ++++++++++++++++++++++++++
 typings/numba.pyi                      |  6 +++--
 19 files changed, 125 insertions(+), 49 deletions(-)

diff --git a/pandas/_config/config.py b/pandas/_config/config.py
index 4d87e8dca6d16..961da3db0ac31 100644
--- a/pandas/_config/config.py
+++ b/pandas/_config/config.py
@@ -56,6 +56,7 @@
 )
 import re
 from typing import (
+    TYPE_CHECKING,
     Any,
     Callable,
     Generator,
@@ -66,12 +67,14 @@
 )
 import warnings
 
-from pandas._typing import (
-    F,
-    T,
-)
 from pandas.util._exceptions import find_stack_level
 
+if TYPE_CHECKING:
+    from pandas._typing import (
+        F,
+        T,
+    )
+
 
 class DeprecatedOption(NamedTuple):
     key: str
diff --git a/pandas/_testing/__init__.py b/pandas/_testing/__init__.py
index 69ca809e4f498..a82a00d3de70a 100644
--- a/pandas/_testing/__init__.py
+++ b/pandas/_testing/__init__.py
@@ -25,11 +25,6 @@
     set_locale,
 )
 
-from pandas._typing import (
-    Dtype,
-    Frequency,
-    NpDtype,
-)
 from pandas.compat import pa_version_under7p0
 
 from pandas.core.dtypes.common import (
@@ -118,6 +113,12 @@
 from pandas.core.construction import extract_array
 
 if TYPE_CHECKING:
+    from pandas._typing import (
+        Dtype,
+        Frequency,
+        NpDtype,
+    )
+
     from pandas import (
         PeriodIndex,
         TimedeltaIndex,
diff --git a/pandas/_testing/_io.py b/pandas/_testing/_io.py
index 29618bdd64912..37a75d9f59920 100644
--- a/pandas/_testing/_io.py
+++ b/pandas/_testing/_io.py
@@ -13,10 +13,6 @@
 )
 import zipfile
 
-from pandas._typing import (
-    FilePath,
-    ReadPickleBuffer,
-)
 from pandas.compat import get_lzma_file
 from pandas.compat._optional import import_optional_dependency
 
@@ -27,6 +23,11 @@
 from pandas.io.common import urlopen
 
 if TYPE_CHECKING:
+    from pandas._typing import (
+        FilePath,
+        ReadPickleBuffer,
+    )
+
     from pandas import (
         DataFrame,
         Series,
diff --git a/pandas/_testing/_random.py b/pandas/_testing/_random.py
index 7cfd92efb5d5f..7abef0f1f48cd 100644
--- a/pandas/_testing/_random.py
+++ b/pandas/_testing/_random.py
@@ -1,9 +1,10 @@
 import string
+from typing import TYPE_CHECKING
 
 import numpy as np
 
-from pandas._typing import NpDtype
-
+if TYPE_CHECKING:
+    from pandas._typing import NpDtype
 RANDS_CHARS = np.array(list(string.ascii_letters + string.digits), dtype=(np.str_, 1))
 
 
diff --git a/pandas/_testing/compat.py b/pandas/_testing/compat.py
index bb3bb99a4c6e4..e5a7f99edaf9e 100644
--- a/pandas/_testing/compat.py
+++ b/pandas/_testing/compat.py
@@ -1,10 +1,13 @@
 """
 Helpers for sharing tests between DataFrame/Series
 """
-from pandas._typing import DtypeObj
+from typing import TYPE_CHECKING
 
 from pandas import DataFrame
 
+if TYPE_CHECKING:
+    from pandas._typing import DtypeObj
+
 
 def get_dtype(obj) -> DtypeObj:
     if isinstance(obj, DataFrame):
diff --git a/pandas/_testing/contexts.py b/pandas/_testing/contexts.py
index bf625a086b9ad..eb1e39ebd9c4d 100644
--- a/pandas/_testing/contexts.py
+++ b/pandas/_testing/contexts.py
@@ -6,16 +6,12 @@
 import tempfile
 from typing import (
     IO,
+    TYPE_CHECKING,
     Any,
     Generator,
 )
 import uuid
 
-from pandas._typing import (
-    BaseBuffer,
-    CompressionOptions,
-    FilePath,
-)
 from pandas.compat import PYPY
 from pandas.errors import ChainedAssignmentError
 
@@ -23,6 +19,13 @@
 
 from pandas.io.common import get_handle
 
+if TYPE_CHECKING:
+    from pandas._typing import (
+        BaseBuffer,
+        CompressionOptions,
+        FilePath,
+    )
+
 
 @contextmanager
 def decompress_file(
diff --git a/pandas/_typing.py b/pandas/_typing.py
index 6059bced4a7d4..ba524e0ff3892 100644
--- a/pandas/_typing.py
+++ b/pandas/_typing.py
@@ -1,11 +1,5 @@
 from __future__ import annotations
 
-from datetime import (
-    datetime,
-    timedelta,
-    tzinfo,
-)
-from os import PathLike
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -25,12 +19,18 @@
     Union,
 )
 
-import numpy as np
-
 # To prevent import cycles place any internal imports in the branch below
 # and use a string literal forward reference to it in subsequent types
 # https://mypy.readthedocs.io/en/latest/common_issues.html#import-cycles
 if TYPE_CHECKING:
+    from datetime import (
+        datetime,
+        timedelta,
+        tzinfo,
+    )
+    from os import PathLike
+
+    import numpy as np
     import numpy.typing as npt
 
     from pandas._libs import (
diff --git a/pandas/compat/__init__.py b/pandas/compat/__init__.py
index 60a9b3d4fd30e..656d5861912b4 100644
--- a/pandas/compat/__init__.py
+++ b/pandas/compat/__init__.py
@@ -12,8 +12,8 @@
 import os
 import platform
 import sys
+from typing import TYPE_CHECKING
 
-from pandas._typing import F
 from pandas.compat._constants import (
     IS64,
     PY39,
@@ -33,6 +33,9 @@
     pa_version_under11p0,
 )
 
+if TYPE_CHECKING:
+    from pandas._typing import F
+
 
 def set_function_name(f: F, name: str, cls) -> F:
     """
diff --git a/pandas/compat/_optional.py b/pandas/compat/_optional.py
index 01ac462eeb659..bcfd4ea790e64 100644
--- a/pandas/compat/_optional.py
+++ b/pandas/compat/_optional.py
@@ -2,13 +2,16 @@
 
 import importlib
 import sys
-import types
+from typing import TYPE_CHECKING
 import warnings
 
 from pandas.util._exceptions import find_stack_level
 
 from pandas.util.version import Version
 
+if TYPE_CHECKING:
+    import types
+
 # Update install.rst & setup.cfg when updating versions!
 
 VERSIONS = {
diff --git a/pandas/compat/numpy/function.py b/pandas/compat/numpy/function.py
index 2c71990d74cb1..ce4f59b41f9b9 100644
--- a/pandas/compat/numpy/function.py
+++ b/pandas/compat/numpy/function.py
@@ -18,6 +18,7 @@
 from __future__ import annotations
 
 from typing import (
+    TYPE_CHECKING,
     Any,
     TypeVar,
     cast,
@@ -30,10 +31,6 @@
     is_bool,
     is_integer,
 )
-from pandas._typing import (
-    Axis,
-    AxisInt,
-)
 from pandas.errors import UnsupportedFunctionCall
 from pandas.util._validators import (
     validate_args,
@@ -41,6 +38,12 @@
     validate_kwargs,
 )
 
+if TYPE_CHECKING:
+    from pandas._typing import (
+        Axis,
+        AxisInt,
+    )
+
 AxisNoneT = TypeVar("AxisNoneT", Axis, None)
 
 
diff --git a/pandas/core/_numba/executor.py b/pandas/core/_numba/executor.py
index 13d8b52bae39c..891772602c442 100644
--- a/pandas/core/_numba/executor.py
+++ b/pandas/core/_numba/executor.py
@@ -6,9 +6,11 @@
     Callable,
 )
 
+if TYPE_CHECKING:
+    from pandas._typing import Scalar
+
 import numpy as np
 
-from pandas._typing import Scalar
 from pandas.compat._optional import import_optional_dependency
 
 
diff --git a/pandas/core/_numba/kernels/shared.py b/pandas/core/_numba/kernels/shared.py
index 6e6bcef590d06..c52372fe6b08f 100644
--- a/pandas/core/_numba/kernels/shared.py
+++ b/pandas/core/_numba/kernels/shared.py
@@ -1,7 +1,11 @@
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 import numba
-import numpy as np
+
+if TYPE_CHECKING:
+    import numpy as np
 
 
 @numba.jit(
diff --git a/pandas/core/computation/expressions.py b/pandas/core/computation/expressions.py
index 2b34258982ab1..10b0670a78d6f 100644
--- a/pandas/core/computation/expressions.py
+++ b/pandas/core/computation/expressions.py
@@ -8,13 +8,13 @@
 from __future__ import annotations
 
 import operator
+from typing import TYPE_CHECKING
 import warnings
 
 import numpy as np
 
 from pandas._config import get_option
 
-from pandas._typing import FuncType
 from pandas.util._exceptions import find_stack_level
 
 from pandas.core.computation.check import NUMEXPR_INSTALLED
@@ -23,6 +23,9 @@
 if NUMEXPR_INSTALLED:
     import numexpr as ne
 
+if TYPE_CHECKING:
+    from pandas._typing import FuncType
+
 _TEST_MODE: bool | None = None
 _TEST_RESULT: list[bool] = []
 USE_NUMEXPR = NUMEXPR_INSTALLED
diff --git a/pandas/core/computation/pytables.py b/pandas/core/computation/pytables.py
index 5c8602c0291da..98ed86e8a4dec 100644
--- a/pandas/core/computation/pytables.py
+++ b/pandas/core/computation/pytables.py
@@ -3,7 +3,10 @@
 
 import ast
 from functools import partial
-from typing import Any
+from typing import (
+    TYPE_CHECKING,
+    Any,
+)
 
 import numpy as np
 
@@ -11,7 +14,6 @@
     Timedelta,
     Timestamp,
 )
-from pandas._typing import npt
 from pandas.errors import UndefinedVariableError
 
 from pandas.core.dtypes.common import is_list_like
@@ -33,6 +35,9 @@
     pprint_thing_encoded,
 )
 
+if TYPE_CHECKING:
+    from pandas._typing import npt
+
 
 class PyTablesScope(_scope.Scope):
     __slots__ = ("queryables",)
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 4c5bc659897d1..e710e9d03f589 100644
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -17,10 +17,6 @@
 
 from pandas._libs.indexing import NDFrameIndexerBase
 from pandas._libs.lib import item_from_zerodim
-from pandas._typing import (
-    Axis,
-    AxisInt,
-)
 from pandas.compat import PYPY
 from pandas.errors import (
     AbstractMethodError,
@@ -79,6 +75,11 @@
 )
 
 if TYPE_CHECKING:
+    from pandas._typing import (
+        Axis,
+        AxisInt,
+    )
+
     from pandas import (
         DataFrame,
         Series,
diff --git a/pandas/core/interchange/utils.py b/pandas/core/interchange/utils.py
index aa717d05aecb5..7faef09d11239 100644
--- a/pandas/core/interchange/utils.py
+++ b/pandas/core/interchange/utils.py
@@ -9,11 +9,12 @@
 
 import numpy as np
 
-from pandas._typing import DtypeObj
-
 import pandas as pd
 from pandas.api.types import is_datetime64_dtype
 
+if typing.TYPE_CHECKING:
+    from pandas._typing import DtypeObj
+
 
 class ArrowCTypes:
     """
diff --git a/pandas/core/sample.py b/pandas/core/sample.py
index a9b236b58a9ba..eebbed3512c4e 100644
--- a/pandas/core/sample.py
+++ b/pandas/core/sample.py
@@ -8,7 +8,6 @@
 import numpy as np
 
 from pandas._libs import lib
-from pandas._typing import AxisInt
 
 from pandas.core.dtypes.generic import (
     ABCDataFrame,
@@ -16,6 +15,8 @@
 )
 
 if TYPE_CHECKING:
+    from pandas._typing import AxisInt
+
     from pandas.core.generic import NDFrame
 
 
diff --git a/pyproject.toml b/pyproject.toml
index baffbd18329ff..c8c84f8c794ec 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -218,6 +218,8 @@ select = [
   "TID",
   # implicit string concatenation
   "ISC",
+  # type-checking imports
+  "TCH",
 ]
 
 ignore = [
@@ -282,6 +284,40 @@ exclude = [
 [tool.ruff.per-file-ignores]
 # relative imports allowed for asv_bench
 "asv_bench/*" = ["TID"]
+# TCH to be enabled gradually
+"pandas/core/arrays/*" = ["TCH"]
+"pandas/core/io/*" = ["TCH"]
+"pandas/core/indexers/*" = ["TCH"]
+"pandas/core/indexes/*" = ["TCH"]
+"pandas/core/internals/*" = ["TCH"]
+"pandas/core/groupby/*" = ["TCH"]
+"pandas/core/methods/*" = ["TCH"]
+"pandas/core/array_algos/*" = ["TCH"]
+"pandas/core/dtypes/*" = ["TCH"]
+"pandas/core/generic.py" = ["TCH"]
+"pandas/core/frame.py" = ["TCH"]
+"pandas/core/series.py" = ["TCH"]
+"pandas/core/resample.py" = ["TCH"]
+"pandas/core/nanops.py" = ["TCH"]
+"pandas/core/apply.py" = ["TCH"]
+"pandas/core/base.py" = ["TCH"]
+"pandas/core/algorithms.py" = ["TCH"]
+"pandas/core/ops/*" = ["TCH"]
+"pandas/core/sorting.py" = ["TCH"]
+"pandas/core/construction.py" = ["TCH"]
+"pandas/core/common.py" = ["TCH"]
+"pandas/core/missing.py" = ["TCH"]
+"pandas/core/util/*" = ["TCH"]
+"pandas/core/reshape/*" = ["TCH"]
+"pandas/core/strings/*" = ["TCH"]
+"pandas/core/tools/*" = ["TCH"]
+"pandas/core/window/*" = ["TCH"]
+"pandas/io/*" = ["TCH"]
+"pandas/tseries/*" = ["TCH"]
+"pandas/tests/*" = ["TCH"]
+"pandas/plotting/*" = ["TCH"]
+"pandas/util/*" = ["TCH"]
+"pandas/_libs/*" = ["TCH"]
 
 [tool.pylint.messages_control]
 max-line-length = 88
diff --git a/typings/numba.pyi b/typings/numba.pyi
index 36cccb894049b..0d9184af19a0f 100644
--- a/typings/numba.pyi
+++ b/typings/numba.pyi
@@ -1,14 +1,16 @@
 # pyright: reportIncompleteStub = false
 from typing import (
+    TYPE_CHECKING,
     Any,
     Callable,
     Literal,
     overload,
 )
 
-import numba
+if TYPE_CHECKING:
+    import numba
 
-from pandas._typing import F
+    from pandas._typing import F
 
 def __getattr__(name: str) -> Any: ...  # incomplete
 @overload

From d4a84c1c6bc271656a24904e96803d16aea21f91 Mon Sep 17 00:00:00 2001
From: MarcoGorelli <>
Date: Tue, 28 Feb 2023 10:36:07 +0000
Subject: [PATCH 2/3] fixup

---
 pandas/_config/config.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/pandas/_config/config.py b/pandas/_config/config.py
index 961da3db0ac31..a5b6fc198c4ac 100644
--- a/pandas/_config/config.py
+++ b/pandas/_config/config.py
@@ -67,13 +67,11 @@
 )
 import warnings
 
+from pandas._typing import T  # noqa: TCH001
 from pandas.util._exceptions import find_stack_level
 
 if TYPE_CHECKING:
-    from pandas._typing import (
-        F,
-        T,
-    )
+    from pandas._typing import F
 
 
 class DeprecatedOption(NamedTuple):

From c3154ad30d5ee44f2c5d3c0a817ae9c972599efd Mon Sep 17 00:00:00 2001
From: MarcoGorelli <>
Date: Tue, 28 Feb 2023 10:42:05 +0000
Subject: [PATCH 3/3] fixup

---
 pandas/_config/config.py        |  5 +----
 pandas/_testing/_random.py      |  2 ++
 pandas/_testing/compat.py       |  2 ++
 pandas/_typing.py               | 16 ++++++++--------
 pandas/compat/numpy/function.py |  2 +-
 pyproject.toml                  |  2 ++
 6 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/pandas/_config/config.py b/pandas/_config/config.py
index a5b6fc198c4ac..0149ea545a4c5 100644
--- a/pandas/_config/config.py
+++ b/pandas/_config/config.py
@@ -56,7 +56,6 @@
 )
 import re
 from typing import (
-    TYPE_CHECKING,
     Any,
     Callable,
     Generator,
@@ -67,12 +66,10 @@
 )
 import warnings
 
+from pandas._typing import F  # noqa: TCH001
 from pandas._typing import T  # noqa: TCH001
 from pandas.util._exceptions import find_stack_level
 
-if TYPE_CHECKING:
-    from pandas._typing import F
-
 
 class DeprecatedOption(NamedTuple):
     key: str
diff --git a/pandas/_testing/_random.py b/pandas/_testing/_random.py
index 7abef0f1f48cd..f0a0437a5bfc6 100644
--- a/pandas/_testing/_random.py
+++ b/pandas/_testing/_random.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import string
 from typing import TYPE_CHECKING
 
diff --git a/pandas/_testing/compat.py b/pandas/_testing/compat.py
index e5a7f99edaf9e..cc352ba7b8f2f 100644
--- a/pandas/_testing/compat.py
+++ b/pandas/_testing/compat.py
@@ -1,6 +1,8 @@
 """
 Helpers for sharing tests between DataFrame/Series
 """
+from __future__ import annotations
+
 from typing import TYPE_CHECKING
 
 from pandas import DataFrame
diff --git a/pandas/_typing.py b/pandas/_typing.py
index ba524e0ff3892..6059bced4a7d4 100644
--- a/pandas/_typing.py
+++ b/pandas/_typing.py
@@ -1,5 +1,11 @@
 from __future__ import annotations
 
+from datetime import (
+    datetime,
+    timedelta,
+    tzinfo,
+)
+from os import PathLike
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -19,18 +25,12 @@
     Union,
 )
 
+import numpy as np
+
 # To prevent import cycles place any internal imports in the branch below
 # and use a string literal forward reference to it in subsequent types
 # https://mypy.readthedocs.io/en/latest/common_issues.html#import-cycles
 if TYPE_CHECKING:
-    from datetime import (
-        datetime,
-        timedelta,
-        tzinfo,
-    )
-    from os import PathLike
-
-    import numpy as np
     import numpy.typing as npt
 
     from pandas._libs import (
diff --git a/pandas/compat/numpy/function.py b/pandas/compat/numpy/function.py
index ce4f59b41f9b9..bdd26b315ed83 100644
--- a/pandas/compat/numpy/function.py
+++ b/pandas/compat/numpy/function.py
@@ -44,7 +44,7 @@
         AxisInt,
     )
 
-AxisNoneT = TypeVar("AxisNoneT", Axis, None)
+    AxisNoneT = TypeVar("AxisNoneT", Axis, None)
 
 
 class CompatValidator:
diff --git a/pyproject.toml b/pyproject.toml
index c8c84f8c794ec..6457db4524d22 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -318,6 +318,8 @@ exclude = [
 "pandas/plotting/*" = ["TCH"]
 "pandas/util/*" = ["TCH"]
 "pandas/_libs/*" = ["TCH"]
+# Keep this one enabled
+"pandas/_typing.py" = ["TCH"]
 
 [tool.pylint.messages_control]
 max-line-length = 88