From ee10d29a0eeded05ad4fa281c90341412f843d0b Mon Sep 17 00:00:00 2001
From: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
Date: Sat, 16 Jul 2022 09:25:38 -0700
Subject: [PATCH] flush keepalives on operator assignment statements (#13144)
 (#13151)

This PR makes mypyc flush keepalives on operator assignment statements, to prevent accessing undefined variables in the generated C code.

Fixes mypyc/mypyc#941.

Co-authored-by: Zsolt Dollenstein <zsol.zsol@gmail.com>
---
 mypyc/irbuild/statement.py          |  1 +
 mypyc/test-data/run-generators.test | 12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/mypyc/irbuild/statement.py b/mypyc/irbuild/statement.py
index 93dc5f24158f..c1d9666a34ec 100644
--- a/mypyc/irbuild/statement.py
+++ b/mypyc/irbuild/statement.py
@@ -136,6 +136,7 @@ def transform_operator_assignment_stmt(builder: IRBuilder, stmt: OperatorAssignm
     # usually operator assignments are done in-place
     # but when target doesn't support that we need to manually assign
     builder.assign(target, res, res.line)
+    builder.flush_keep_alives()
 
 
 def transform_import(builder: IRBuilder, node: Import) -> None:
diff --git a/mypyc/test-data/run-generators.test b/mypyc/test-data/run-generators.test
index 8aecce6564c8..8feabd21258b 100644
--- a/mypyc/test-data/run-generators.test
+++ b/mypyc/test-data/run-generators.test
@@ -595,3 +595,15 @@ class C:
         self.foo.flag = True
         yield
         self.foo.flag = False
+
+[case testGeneratorEarlyReturnWithBorrows]
+from typing import Iterator
+class Bar:
+    bar = 0
+class Foo:
+    bar = Bar()
+    def f(self) -> Iterator[int]:
+        if self:
+            self.bar.bar += 1
+            return
+        yield 0
\ No newline at end of file