fix: class definition bug

crates/erg_compiler/lower.rs

@@ -2352,9 +2352,11 @@ impl<A: ASTBuildable> GenericASTLowerer<A> {
         let Some(hir::Expr::Call(call)) = hir_def.body.block.first() else {
             return unreachable_error!(LowerErrors, LowerError, self);
         };
-        if let Some(sup_type) = call.args.get_left_or_key("Super") {
-            if let Err(err) = self.check_inheritable(type_obj, sup_type, &hir_def.sig) {
-                self.errs.extend(err);
+        if hir_def.def_kind().is_inherit() {
+            if let Some(sup_type) = call.args.get_left_or_key("Super") {
+                if let Err(err) = self.check_inheritable(type_obj, sup_type, &hir_def.sig) {
+                    self.errs.extend(err);
+                }
             }
         }
         let Some(constructor) =

crates/erg_parser/ast.rs

@@ -5553,6 +5553,10 @@ impl DefKind {
         matches!(self, Self::Class | Self::Inherit)
     }
 
+    pub const fn is_inherit(&self) -> bool {
+        matches!(self, Self::Inherit)
+    }
+
     pub const fn is_class_or_trait(&self) -> bool {
         self.is_class() || self.is_trait()
     }

tests/should_ok/recursive_class.er

@@ -0,0 +1,21 @@
+F = Class((obj: Obj) -> F)
+
+greedy(obj) =
+    log obj
+    F.new greedy
+
+_ = greedy(1)::base(1)::base(1)
+
+Leaf = Class Int
+Leaf|<: Show|.
+    __str__ ref self = "Leaf(\{self::base})"
+Node = Class { left = Tree; right = Tree }
+Node|<: Show|.
+    __str__ ref self = "Node{ left = \{self::left}; right = \{self::right} }"
+Tree = Class Node or Leaf
+Tree|<: Show|.
+    __str__ ref self = match self::base:
+        (l: Leaf) -> l.__str__()
+        (n: Node)-> n.__str__()
+
+print! Node.new { left = Tree.new Leaf.new 1; right = Tree.new Leaf.new 2 }

tests/test.rs

@@ -344,6 +344,11 @@ fn exec_record_err() -> Result<(), ()> {
     expect_failure("tests/should_err/record.er", 0, 1)
 }
 
+#[test]
+fn exec_recursive_class() -> Result<(), ()> {
+    expect_success("tests/should_ok/recursive_class.er", 0)
+}
+
 #[test]
 fn exec_refinement() -> Result<(), ()> {
     expect_success("tests/should_ok/refinement.er", 0)