fix: clarify implicit abstract class diagnostic

packages/pyright-internal/src/localization/package.nls.en-us.json

@@ -492,7 +492,7 @@
             "message": "Class \"{type}\" is marked final and must implement all abstract symbols",
             "comment": "{Locked='final'}"
         },
-        "classImplicitlyAbstract": "Class \"{type}\" is implicitly abstract because it extends an abstract class without implementing all abstract symbols. If this is intentional, add `ABC` to its base classes or use `metaclass=ABCMeta`.",
+        "classImplicitlyAbstract": "Class \"{type}\" is implicitly abstract because it extends an abstract class but still contains abstract symbols. If this is intentional, add `ABC` to its base classes or use `metaclass=ABCMeta`.",
         "classImplicitlyProtocol": "Class \"{type}\" is implicitly a `Protocol` because it extends a `Protocol` without implementing all abstract symbols. If this is intentional, add `Protocol` or `ABC` to its base classes, or use `metaclass=ABCMeta`.",
         "finalContext": {
             "message": "\"Final\" is not allowed in this context",

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

@@ -813,8 +813,19 @@ test('reportImplicitAbstractClass', () => {
     const analysisResults = TestUtils.typeAnalyzeSampleFiles(['implicitAbstractClass.py'], configOptions);
     TestUtils.validateResultsButBased(analysisResults, {
         errors: [
-            { code: DiagnosticRule.reportImplicitAbstractClass, line: 7 },
+            {
+                code: DiagnosticRule.reportImplicitAbstractClass,
+                line: 7,
+                message:
+                    'Class "B" is implicitly abstract because it extends an abstract class but still contains abstract symbols. If this is intentional, add `ABC` to its base classes or use `metaclass=ABCMeta`.\n  "A.asdf" is not implemented',
+            },
             { code: DiagnosticRule.reportImplicitAbstractClass, line: 25 },
+            {
+                code: DiagnosticRule.reportImplicitAbstractClass,
+                line: 33,
+                message:
+                    'Class "J" is implicitly abstract because it extends an abstract class but still contains abstract symbols. If this is intentional, add `ABC` to its base classes or use `metaclass=ABCMeta`.\n  "J.asdf" is not implemented',
+            },
         ],
     });
 });

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

@@ -27,4 +27,10 @@ class G(F): # error
     pass
 
 class H(F, Protocol):
-    pass
+    pass
+
+class I(ABC): ...
+
+class J(I): # error
+    @abstractmethod
+    def asdf(self) -> int: ...