From 30a95a16d0e0e9ddf89c00c559dae7354163b5b0 Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Sat, 15 May 2021 21:14:50 +0300
Subject: [PATCH 1/2] Do not allow use Final and ClassVar at same time

---
 mypy/semanal.py                 | 5 +++++
 test-data/unit/check-final.test | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/mypy/semanal.py b/mypy/semanal.py
index f157c795d9393..59d68421beab6 100644
--- a/mypy/semanal.py
+++ b/mypy/semanal.py
@@ -2295,6 +2295,11 @@ def unwrap_final(self, s: AssignmentStmt) -> bool:
                 self.fail("Type in Final[...] can only be omitted if there is an initializer", s)
         else:
             s.type = s.unanalyzed_type.args[0]
+
+        if s.type is not None and self.is_classvar(s.type):
+            self.fail("Variable should not be annotated with both ClassVar and Final", s)
+            return False
+
         if len(s.lvalues) != 1 or not isinstance(s.lvalues[0], RefExpr):
             self.fail("Invalid final declaration", s)
             return False
diff --git a/test-data/unit/check-final.test b/test-data/unit/check-final.test
index 6f4077d9cff86..20c0591bb1356 100644
--- a/test-data/unit/check-final.test
+++ b/test-data/unit/check-final.test
@@ -1082,3 +1082,10 @@ class A:
         self.x = 10  # type: Final
         undefined  # type: ignore
 [builtins fixtures/tuple.pyi]
+
+[case testFinalUsedWithClassVar]
+from typing import Final, ClassVar
+
+class A:
+    a: Final[ClassVar[int]]  # E: Variable should not be annotated with both ClassVar and Final
+[out]
\ No newline at end of file

From dd80df8609c8a2b955367f5c49f0bcc3a475d999 Mon Sep 17 00:00:00 2001
From: Yurii Karabas <1998uriyyo@gmail.com>
Date: Sun, 16 May 2021 19:53:30 +0300
Subject: [PATCH 2/2] Add more tests for ClassVar and Final usage

---
 test-data/unit/check-final.test | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test-data/unit/check-final.test b/test-data/unit/check-final.test
index 20c0591bb1356..063b2b8aba886 100644
--- a/test-data/unit/check-final.test
+++ b/test-data/unit/check-final.test
@@ -1088,4 +1088,6 @@ from typing import Final, ClassVar
 
 class A:
     a: Final[ClassVar[int]]  # E: Variable should not be annotated with both ClassVar and Final
+    b: ClassVar[Final[int]]  # E: Final can be only used as an outermost qualifier in a variable annotation
+    c: ClassVar[Final] = 1  # E: Final can be only used as an outermost qualifier in a variable annotation
 [out]
\ No newline at end of file