Fix false positive for function-redefined for simple type annotations

Closes pylint-dev#4936

ChangeLog

@@ -39,6 +39,10 @@ Release date: TBA
 
   Closes #3802
 
+* Fix false positive for ``function-redefined`` for simple type annotations
+
+  Closes #4936
+
 
 What's New in Pylint 2.10.3?
 ============================

doc/whatsnew/2.11.rst

@@ -41,3 +41,7 @@ Other Changes
 * Added ``py-version`` config key (if ``[MASTER]`` section). Used for version dependant checks.
   Will default to whatever Python version pylint is executed with.
 * The ``invalid-name`` message is now more detailed when using multiple naming style regexes.
+
+* Fix false positive for ``function-redefined`` for simple type annotations
+
+  Closes #4936

pylint/checkers/base.py

@@ -862,7 +862,11 @@ def _check_redefinition(self, redeftype, node):
         parent_frame = node.parent.frame()
 
         # Ignore function stubs created for type information
-        redefinitions = parent_frame.locals[node.name]
+        redefinitions = [
+            i
+            for i in parent_frame.locals[node.name]
+            if not (isinstance(i.parent, nodes.AnnAssign) and i.parent.simple)
+        ]
         defined_self = next(
             (local for local in redefinitions if not utils.is_overload_stub(local)),
             node,

tests/functional/f/function_redefined.py

@@ -1,6 +1,9 @@
 # pylint: disable=no-self-use,missing-docstring,using-constant-test, useless-object-inheritance
 # pylint: disable=unused-import,wrong-import-position,reimported, unnecessary-pass
 from __future__ import division
+
+from typing import Callable
+
 __revision__ = ''
 class AAAA(object):
     """docstring"""
@@ -118,3 +121,8 @@ def callback1():
         def callback2():
             return 24
     return callback1(), callback2()
+
+do_something: Callable[[], int]
+
+def do_something() -> int:
+    return 1

tests/functional/f/function_redefined.txt

@@ -1,7 +1,7 @@
-function-redefined:15:4:AAAA.method2:method already defined line 12
-function-redefined:18:0:AAAA:class already defined line 5
-function-redefined:32:0:func2:function already defined line 29
-redefined-outer-name:34:4:func2:Redefining name '__revision__' from outer scope (line 4)
-function-redefined:51:4:exclusive_func2:function already defined line 45
-function-redefined:86:0:ceil:function already defined line 85
-function-redefined:90:0:math:function already defined line 89
+function-redefined:18:4:AAAA.method2:method already defined line 15:HIGH
+function-redefined:21:0:AAAA:class already defined line 8:HIGH
+function-redefined:35:0:func2:function already defined line 32:HIGH
+redefined-outer-name:37:4:func2:Redefining name '__revision__' from outer scope (line 7):HIGH
+function-redefined:54:4:exclusive_func2:function already defined line 48:HIGH
+function-redefined:89:0:ceil:function already defined line 88:HIGH
+function-redefined:93:0:math:function already defined line 92:HIGH