From 4bf402836448baed4e993772ff8a02b49f8e119f Mon Sep 17 00:00:00 2001
From: Ivan Levkivskyi <levkivslyi@gmail.com>
Date: Tue, 30 May 2017 10:32:14 +0200
Subject: [PATCH] Don't warn about returning Any if it is a proper subtype of
 the return type

---
 mypy/checker.py                    |  3 ++-
 test-data/unit/check-warnings.test | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/mypy/checker.py b/mypy/checker.py
index 56ff993ea694..a492b6e035dc 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -1874,7 +1874,8 @@ def check_return_stmt(self, s: ReturnStmt) -> None:
                 if isinstance(typ, AnyType):
                     # (Unless you asked to be warned in that case, and the
                     # function is not declared to return Any)
-                    if not isinstance(return_type, AnyType) and self.options.warn_return_any:
+                    if (not is_proper_subtype(AnyType(), return_type) and
+                            self.options.warn_return_any):
                         self.warn(messages.RETURN_ANY.format(return_type), s)
                     return
 
diff --git a/test-data/unit/check-warnings.test b/test-data/unit/check-warnings.test
index 2f2d592b13fd..c95baec1cc93 100644
--- a/test-data/unit/check-warnings.test
+++ b/test-data/unit/check-warnings.test
@@ -165,3 +165,20 @@ from typing import Any
 def g() -> Any: pass
 def f() -> Any: return g()
 [out]
+
+[case testOKReturnAnyIfProperSubtype]
+# flags: --warn-return-any --strict-optional
+from typing import Any, Optional
+
+class Test(object):
+
+    def __init__(self) -> None:
+        self.attr = "foo"  # type: Any
+
+    def foo(self, do_it: bool) -> Optional[Any]:
+        if do_it:
+            return self.attr  # Should not warn here
+        else:
+            return None
+[builtins fixtures/list.pyi]
+[out]