Fixed a bug that results in incorrect handling of a "bare" ClassVar a…

…nnotation either with or without an assignment. This addresses #9720. (#9724)

packages/pyright-internal/src/analyzer/typeEvaluator.ts

@@ -22961,7 +22961,13 @@ export function createTypeEvaluator(
 
             type = combineTypes(typesToCombine);
         } else {
-            type = UnboundType.create();
+            // We can encounter this situation in the case of a bare ClassVar annotation.
+            if (symbol.isClassVar()) {
+                type = UnknownType.create();
+                isIncomplete = false;
+            } else {
+                type = UnboundType.create();
+            }
         }
 
         return { type, isIncomplete, includesSpeculativeResult, evaluationAttempts };

packages/pyright-internal/src/tests/samples/classVar7.py

@@ -0,0 +1,38 @@
+# This sample tests the handling of a "bare" ClassVar with no
+# subscript.
+
+from typing import ClassVar
+
+
+class A:
+    a: ClassVar
+    b: ClassVar = 2
+    c: ClassVar
+    d: ClassVar
+
+    d = 3
+
+    @classmethod
+    def m1(cls) -> None:
+        cls.c = ""
+
+
+reveal_type(A.a, expected_text="Unknown")
+A.a = 3
+A.a = ""
+
+reveal_type(A.b, expected_text="int")
+A.b = 2
+
+# This should generate an error
+A.b = ""
+
+reveal_type(A.c, expected_text="Unknown")
+A.c = 2
+A.c = ""
+
+reveal_type(A.d, expected_text="int")
+A.d = 2
+
+# This should generate an error
+A.d = ""

packages/pyright-internal/src/tests/typeEvaluator7.test.ts

@@ -811,6 +811,12 @@ test('ClassVar6', () => {
     TestUtils.validateResults(analysisResults, 4);
 });
 
+test('ClassVar7', () => {
+    const analysisResults = TestUtils.typeAnalyzeSampleFiles(['classVar7.py']);
+
+    TestUtils.validateResults(analysisResults, 2);
+});
+
 test('TypeVar1', () => {
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['typeVar1.py']);