fix: parsing of recursive interface types

_test/interface36.go

@@ -0,0 +1,37 @@
+package main
+
+import "fmt"
+
+var (
+	t *S
+	_ I = t
+	_ J = t
+)
+
+type S struct {
+	Name string
+}
+
+func (s *S) F() int { return len(s.Name) }
+func (s *S) G() int { return s.F() }
+func (s *S) Ri() I  { return s }
+func (s *S) Rj() J  { return s }
+
+type J interface {
+	I
+	G() int
+	Rj() J
+}
+
+type I interface {
+	F() int
+	Ri() I
+}
+
+func main() {
+	var j J
+	fmt.Println(j)
+}
+
+// Output:
+// <nil>

interp/type.go

@@ -423,6 +423,7 @@ func nodeType(interp *Interpreter, sc *scope, n *node) (*itype, error) {
 
 	case interfaceType:
 		t.cat = interfaceT
+		var incomplete bool
 		if sname := typeName(n); sname != "" {
 			if sym, _, found := sc.lookup(sname); found && sym.kind == typeSym {
 				sym.typ = t
@@ -435,16 +436,17 @@ func nodeType(interp *Interpreter, sc *scope, n *node) (*itype, error) {
 					return nil, err
 				}
 				t.field = append(t.field, structField{name: fieldName(field.child[0]), embed: true, typ: typ})
-				t.incomplete = t.incomplete || typ.incomplete
+				incomplete = incomplete || typ.incomplete
 			} else {
 				typ, err := nodeType(interp, sc, field.child[1])
 				if err != nil {
 					return nil, err
 				}
 				t.field = append(t.field, structField{name: field.child[0].ident, typ: typ})
-				t.incomplete = t.incomplete || typ.incomplete
+				incomplete = incomplete || typ.incomplete
 			}
 		}
+		t.incomplete = incomplete
 
 	case landExpr, lorExpr:
 		t.cat = boolT