initial commit for issue 2918

Author: Louisvranderick

pyrefly/lib/alt/call.rs

@@ -365,9 +365,15 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
                     // If the class has an unknown base (e.g. inherits from an
                     // unresolved name), it might have inherited `__call__` from
                     // that base, so treat it as callable with implicit Any.
+                    //
+                    // `NotImplemented` is a singleton instance of `NotImplementedType`; it must
+                    // never be treated as callable even when stubs use `NotImplementedType(Any)`,
+                    // which would otherwise set `has_base_any` and hit this branch.
                     None if self
                         .get_metadata_for_class(cls.class_object())
-                        .has_base_any() =>
+                        .has_base_any()
+                        && !cls.has_qname("types", "NotImplementedType")
+                        && !cls.has_qname("builtins", "_NotImplementedType") =>
                     {
                         CallTargetLookup::Ok(Box::new(CallTarget::Any(AnyStyle::Implicit)))
                     }
@@ -1029,10 +1035,7 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
             && meta.kind == FunctionKind::Dataclass
             && let Some(first_ty) = self.first_arg_type(args, errors)
         {
-            let first_arg_range = args
-                .first()
-                .map(|a| a.range())
-                .unwrap_or(arguments_range);
+            let first_arg_range = args.first().map(|a| a.range()).unwrap_or(arguments_range);
             self.map_over_union(&first_ty, |ty| {
                 if let Some((_, inner)) = self.unwrap_class_object_silently(ty) {
                     if let Type::ClassType(ct) = inner

pyrefly/lib/alt/class/class_metadata.rs

@@ -390,10 +390,7 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
                 errors,
                 cls.range(),
                 ErrorInfo::Kind(ErrorKind::BadClassDefinition),
-                format!(
-                    "Cannot apply @dataclass to Enum class `{}`",
-                    cls.name()
-                ),
+                format!("Cannot apply @dataclass to Enum class `{}`", cls.name()),
             );
             dataclass_metadata = None;
         }

pyrefly/lib/test/callable.rs

@@ -1449,3 +1449,13 @@ def after_func() -> None: ...
 schedule(1000, after_func)
 "#,
 );
+
+// Regression test for https://github.com/facebook/pyrefly/issues/2918
+testcase!(
+    test_notimplemented_not_callable,
+    r#"
+NotImplemented()  # E: Expected a callable
+NotImplemented("not yet done")  # E: Expected a callable
+raise NotImplementedError()
+"#,
+);