From 8b7cf89f94643c5688b6409c4cc54d292051ba81 Mon Sep 17 00:00:00 2001
From: Diego Argueta <diego@goodrx.com>
Date: Thu, 11 Mar 2021 11:47:27 -0800
Subject: [PATCH 1/3] Narrower typing on Factory called with takes_self

---
 src/attr/__init__.pyi   | 11 +++++++++--
 tests/typing_example.py |  7 +++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/attr/__init__.pyi b/src/attr/__init__.pyi
index 3cbe709e3..e78fae07c 100644
--- a/src/attr/__init__.pyi
+++ b/src/attr/__init__.pyi
@@ -4,6 +4,7 @@ from typing import (
     Dict,
     Generic,
     List,
+    Literal,
     Mapping,
     Optional,
     Sequence,
@@ -64,9 +65,15 @@ NOTHING: object
 def Factory(factory: Callable[[], _T]) -> _T: ...
 @overload
 def Factory(
-    factory: Union[Callable[[Any], _T], Callable[[], _T]],
-    takes_self: bool = ...,
+    factory: Callable[[Any], _T],
+    takes_self: Literal[True],
 ) -> _T: ...
+@overload
+def Factory(
+    factory: Callable[[], _T],
+    takes_self: Literal[False],
+) -> _T: ...
+
 
 class Attribute(Generic[_T]):
     name: str
diff --git a/tests/typing_example.py b/tests/typing_example.py
index db05dec3b..13b5638db 100644
--- a/tests/typing_example.py
+++ b/tests/typing_example.py
@@ -250,3 +250,10 @@ class NGFrozen:
 @attr.s(collect_by_mro=True)
 class MRO:
     pass
+
+
+@attr.s
+class FactoryTest:
+    a: List[int] = attr.ib(default=attr.Factory(list))
+    b: List[Any] = attr.ib(default=attr.Factory(list, False))
+    c: List[int] = attr.ib(default=attr.Factory((lambda s: s.a), True))

From 05cc09650bb296d2b267f930ff12db36934170fb Mon Sep 17 00:00:00 2001
From: Diego Argueta <dargueta@users.noreply.github.com>
Date: Mon, 22 Mar 2021 11:05:10 -0700
Subject: [PATCH 2/3] Make Literal annotation depend on Python version

---
 src/attr/__init__.pyi | 37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/attr/__init__.pyi b/src/attr/__init__.pyi
index e78fae07c..072547c23 100644
--- a/src/attr/__init__.pyi
+++ b/src/attr/__init__.pyi
@@ -1,10 +1,10 @@
+import sys
 from typing import (
     Any,
     Callable,
     Dict,
     Generic,
     List,
-    Literal,
     Mapping,
     Optional,
     Sequence,
@@ -61,18 +61,29 @@ NOTHING: object
 # NOTE: Factory lies about its return type to make this possible:
 # `x: List[int] # = Factory(list)`
 # Work around mypy issue #4554 in the common case by using an overload.
-@overload
-def Factory(factory: Callable[[], _T]) -> _T: ...
-@overload
-def Factory(
-    factory: Callable[[Any], _T],
-    takes_self: Literal[True],
-) -> _T: ...
-@overload
-def Factory(
-    factory: Callable[[], _T],
-    takes_self: Literal[False],
-) -> _T: ...
+if sys.version_info >= (3, 8):
+    from typing import Literal
+
+    @overload
+    def Factory(factory: Callable[[], _T]) -> _T: ...
+    @overload
+    def Factory(
+        factory: Callable[[Any], _T],
+        takes_self: Literal[True],
+    ) -> _T: ...
+    @overload
+    def Factory(
+        factory: Callable[[], _T],
+        takes_self: Literal[False],
+    ) -> _T: ...
+else:
+    @overload
+    def Factory(factory: Callable[[], _T]) -> _T: ...
+    @overload
+    def Factory(
+        factory: Union[Callable[[Any], _T], Callable[[], _T]],
+        takes_self: bool = ...,
+    ) -> _T: ...
 
 
 class Attribute(Generic[_T]):

From 4adb22b5d09e830562c476038f6614cfee271ebc Mon Sep 17 00:00:00 2001
From: Diego Argueta <diego@goodrx.com>
Date: Tue, 23 Mar 2021 10:08:42 -0700
Subject: [PATCH 3/3] Fix linting error

---
 src/attr/__init__.pyi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/attr/__init__.pyi b/src/attr/__init__.pyi
index 072547c23..cdf9a9ff0 100644
--- a/src/attr/__init__.pyi
+++ b/src/attr/__init__.pyi
@@ -1,4 +1,5 @@
 import sys
+
 from typing import (
     Any,
     Callable,