From 620347af428358459c3781223959806c0496dee7 Mon Sep 17 00:00:00 2001
From: Pierre Sassoulas <pierre.sassoulas@gmail.com>
Date: Sat, 9 Apr 2022 19:27:37 +0200
Subject: [PATCH] Suppress `unsubscriptable-object` warnings in type-checking
 blocks (#5720)

* Add a regression test for issue #3979

* Don't emit `unsubscriptable-object` for statements in type-checking blocks

Co-authored-by: Jacob Walls <jacobtylerwalls@gmail.com>
---
 ChangeLog                                           |  5 +++++
 doc/whatsnew/2.14.rst                               |  5 +++++
 pylint/checkers/typecheck.py                        |  6 +++++-
 tests/functional/r/regression_02/regression_3979.py | 13 +++++++++++++
 4 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 tests/functional/r/regression_02/regression_3979.py

diff --git a/ChangeLog b/ChangeLog
index d6b71e6c28..71c9142c0e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -62,6 +62,11 @@ Release date: TBA
 
   Closes #4525
 
+* Fix false positive for ``unsubscriptable-object`` in Python 3.8 and below for
+  statements guarded by ``if TYPE_CHECKING``.
+
+  Closes #3979
+
 * Fix false negative for ``no-member`` when attempting to assign an instance
   attribute to itself without any prior assignment.
 
diff --git a/doc/whatsnew/2.14.rst b/doc/whatsnew/2.14.rst
index ce3c1cedfe..5ffb55052e 100644
--- a/doc/whatsnew/2.14.rst
+++ b/doc/whatsnew/2.14.rst
@@ -81,6 +81,11 @@ Other Changes
 
   Closes #5205
 
+* Fix false positive for ``unsubscriptable-object`` in Python 3.8 and below for
+  statements guarded by ``if TYPE_CHECKING``.
+
+  Closes #3979
+
 * Fix false negative for ``no-member`` when attempting to assign an instance
   attribute to itself without any prior assignment.
 
diff --git a/pylint/checkers/typecheck.py b/pylint/checkers/typecheck.py
index 2ab5ced330..5b3c6a372e 100644
--- a/pylint/checkers/typecheck.py
+++ b/pylint/checkers/typecheck.py
@@ -1951,7 +1951,11 @@ def visit_subscript(self, node: nodes.Subscript) -> None:
                 return  # It would be better to handle function
                 # decorators, but let's start slow.
 
-        if supported_protocol and not supported_protocol(inferred, node):
+        if (
+            supported_protocol
+            and not supported_protocol(inferred, node)
+            and not utils.in_type_checking_block(node)
+        ):
             self.add_message(msg, args=node.value.as_string(), node=node.value)
 
     @check_messages("dict-items-missing-iter")
diff --git a/tests/functional/r/regression_02/regression_3979.py b/tests/functional/r/regression_02/regression_3979.py
new file mode 100644
index 0000000000..4fb0c5a051
--- /dev/null
+++ b/tests/functional/r/regression_02/regression_3979.py
@@ -0,0 +1,13 @@
+"""
+Regression test for https://github.com/PyCQA/pylint/issues/3979
+"""
+
+import os
+from typing import TYPE_CHECKING, Any, Union
+
+if TYPE_CHECKING:
+    BasePathLike = os.PathLike[Any]  # <-- pylint used to emit E1136 here
+else:
+    BasePathLike = os.PathLike
+
+foo: Union[str, BasePathLike] = "bar"