From 4c4cf8fbff4eb8288cc6e7ef4616c30b034f3ff1 Mon Sep 17 00:00:00 2001
From: hauntsaninja <hauntsaninja@gmail.com>
Date: Thu, 10 Nov 2022 17:33:40 -0800
Subject: [PATCH 1/2] Fix crash with function redefinition

Fixes #14027
---
 mypy/checker.py                     |  6 +++++-
 test-data/unit/check-functions.test | 11 +++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/mypy/checker.py b/mypy/checker.py
index fef85d085496..328304792171 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -960,7 +960,11 @@ def _visit_func_def(self, defn: FuncDef) -> None:
                 # Function definition overrides a variable initialized via assignment or a
                 # decorated function.
                 orig_type = defn.original_def.type
-                assert orig_type is not None, f"Error checking function redefinition {defn}"
+                if orig_type is None:
+                    # I'm not sure why this happens, probably a bug elsewhere
+                    # See testConditionalFunctionDefinitionWithTuple
+                    # Setting orig_type to UninhabitedType ensures an error is reported
+                    orig_type = UninhabitedType()
                 if isinstance(orig_type, PartialType):
                     if orig_type.type is None:
                         # Ah this is a partial type. Give it the type of the function.
diff --git a/test-data/unit/check-functions.test b/test-data/unit/check-functions.test
index bb36b65f35de..697a81d3803b 100644
--- a/test-data/unit/check-functions.test
+++ b/test-data/unit/check-functions.test
@@ -1475,6 +1475,17 @@ else:
     @dec
     def f(): pass
 
+[case testConditionalFunctionDefinitionWithTuple]
+def bar() -> None:
+    # weirdly, needs to be an empty tuple. empty lists and various other special assignments
+    # don't trigger the bug
+    cond = ()
+    if cond:
+        foo = 1
+    else:
+        def foo(obj): ...  # E: Incompatible redefinition (redefinition with type "Callable[[Any], Any]", original type <nothing>)
+[builtins fixtures/tuple.pyi]
+
 [case testConditionalRedefinitionOfAnUnconditionalFunctionDefinition1]
 from typing import Any
 def f(x: str) -> None: pass

From c3739994f88c897f558c72ad9471243ecf404128 Mon Sep 17 00:00:00 2001
From: hauntsaninja <hauntsaninja@gmail.com>
Date: Fri, 11 Nov 2022 11:03:49 -0800
Subject: [PATCH 2/2] code review

---
 mypy/checker.py                     |  7 +++----
 test-data/unit/check-functions.test | 15 +++++++++------
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/mypy/checker.py b/mypy/checker.py
index 328304792171..dfd7ca5e857e 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -961,10 +961,9 @@ def _visit_func_def(self, defn: FuncDef) -> None:
                 # decorated function.
                 orig_type = defn.original_def.type
                 if orig_type is None:
-                    # I'm not sure why this happens, probably a bug elsewhere
-                    # See testConditionalFunctionDefinitionWithTuple
-                    # Setting orig_type to UninhabitedType ensures an error is reported
-                    orig_type = UninhabitedType()
+                    # If other branch is unreachable, we don't type check it and so we might
+                    # not have a type for the original definition
+                    return
                 if isinstance(orig_type, PartialType):
                     if orig_type.type is None:
                         # Ah this is a partial type. Give it the type of the function.
diff --git a/test-data/unit/check-functions.test b/test-data/unit/check-functions.test
index 697a81d3803b..ae6424f743be 100644
--- a/test-data/unit/check-functions.test
+++ b/test-data/unit/check-functions.test
@@ -1475,15 +1475,18 @@ else:
     @dec
     def f(): pass
 
-[case testConditionalFunctionDefinitionWithTuple]
+[case testConditionalFunctionDefinitionUnreachable]
 def bar() -> None:
-    # weirdly, needs to be an empty tuple. empty lists and various other special assignments
-    # don't trigger the bug
-    cond = ()
-    if cond:
+    if False:
         foo = 1
     else:
-        def foo(obj): ...  # E: Incompatible redefinition (redefinition with type "Callable[[Any], Any]", original type <nothing>)
+        def foo(obj): ...
+
+def baz() -> None:
+    if False:
+        foo: int = 1
+    else:
+        def foo(obj): ...  # E: Incompatible redefinition (redefinition with type "Callable[[Any], Any]", original type "int")
 [builtins fixtures/tuple.pyi]
 
 [case testConditionalRedefinitionOfAnUnconditionalFunctionDefinition1]