From fb551466ba7780e1421c28abd88f576d2bbe5d6c Mon Sep 17 00:00:00 2001
From: Ivan Levkivskyi <levkivskyi@gmail.com>
Date: Thu, 27 Jun 2019 17:08:21 +0100
Subject: [PATCH 1/2] Add tests

---
 test-data/unit/fine-grained.test | 58 ++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/test-data/unit/fine-grained.test b/test-data/unit/fine-grained.test
index 3ca3eec68e12..9a8301463fc7 100644
--- a/test-data/unit/fine-grained.test
+++ b/test-data/unit/fine-grained.test
@@ -8992,3 +8992,61 @@ def bar() -> str: return '0'
 main:9: error: Argument 1 to "foo" has incompatible type "int"; expected "str"
 ==
 main:9: error: Argument 1 to "foo" has incompatible type "int"; expected "str"
+
+[case testInfiniteLoop]
+# flags: --new-semantic-analyzer
+[file a.py]
+from b import f
+from typing import Callable, TypeVar
+
+F = TypeVar('F', bound=Callable)
+def dec(x: F) -> F: return x
+
+@dec
+def foo(self):
+    class A:
+        @classmethod
+        def asdf(cls, x: 'A') -> None: pass
+
+@dec
+def bar(self):
+    class B:
+        @classmethod
+        def asdf(cls, x: 'B') -> None: pass
+    f()
+
+[file b.py]
+def f() -> int: pass
+[file b.py.2]
+def f() -> str: pass
+[builtins fixtures/classmethod.pyi]
+[out]
+==
+
+[case testInfiniteLoop2]
+# flags: --new-semantic-analyzer
+[file a.py]
+from b import f
+from typing import Callable, TypeVar, NamedTuple
+
+F = TypeVar('F', bound=Callable)
+def dec(x: F) -> F: return x
+
+@dec
+def foo(self):
+    N = NamedTuple('N', [('x', int)])
+    def g(x: N) -> None: pass
+
+@dec
+def bar(self):
+    N = NamedTuple('N', [('x', int)])
+    def g(x: N) -> None: pass
+    f()
+
+[file b.py]
+def f() -> int: pass
+[file b.py.2]
+def f() -> str: pass
+[builtins fixtures/classmethod.pyi]
+[out]
+==

From 011607e09ce0befb935f34217a963f1bb0d58539 Mon Sep 17 00:00:00 2001
From: Ivan Levkivskyi <levkivskyi@gmail.com>
Date: Thu, 27 Jun 2019 17:53:40 +0100
Subject: [PATCH 2/2] Quick and dirty fix for nested classes in fine grained
 mode

---
 mypy/server/aststripnew.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mypy/server/aststripnew.py b/mypy/server/aststripnew.py
index 99fe228ef0c1..126751607f7b 100644
--- a/mypy/server/aststripnew.py
+++ b/mypy/server/aststripnew.py
@@ -62,7 +62,11 @@ def strip_file_top_level(self, file_node: MypyFile) -> None:
         self.recurse_into_functions = False
         file_node.plugin_deps.clear()
         file_node.accept(self)
-        file_node.names.clear()
+        for name in file_node.names.copy():
+            # TODO: this is a hot fix, we should delete all names,
+            # see https://github.com/python/mypy/issues/6422.
+            if '@' not in name:
+                del file_node.names[name]
 
     def visit_block(self, b: Block) -> None:
         if b.is_unreachable: