parser: check assign expr with undefined variables of struct_init (#13495)

vlib/v/checker/tests/assign_expr_undefined_err_l.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/assign_expr_undefined_err_l.vv:29:6: error: undefined variable: `poo`
+   27 |     poo := Stru{
+   28 |         a: 123
+   29 |         i: poo.result()
+      |            ~~~
+   30 |     }
+   31 |      println('$poo')

vlib/v/checker/tests/assign_expr_undefined_err_l.vv

@@ -0,0 +1,32 @@
+module main
+
+struct Stru {
+mut:
+	a int
+	i Iface2
+}
+
+interface Iface {
+	result() &Iface2
+}
+
+interface Iface2 {
+	result2() Iface
+}
+
+pub fn (s Stru)result() &Iface2 {
+	return &Stru{}
+}
+
+pub fn (s Stru)result2() Iface {
+	return &Stru{}
+}
+
+fn main() {
+	println('hello world')
+	poo := Stru{
+		a: 123
+		i: poo.result()
+	}
+ 	println('$poo')
+}

vlib/v/parser/assign.v

@@ -18,7 +18,7 @@ fn (mut p Parser) assign_stmt() ast.Stmt {
 	return p.partial_assign_stmt(exprs, comments)
 }
 
-const max_expr_level = 310
+const max_expr_level = 100
 
 fn (mut p Parser) check_undefined_variables(exprs []ast.Expr, val ast.Expr) ? {
 	p.expr_level++
@@ -85,6 +85,12 @@ fn (mut p Parser) check_undefined_variables(exprs []ast.Expr, val ast.Expr) ? {
 				p.check_undefined_variables(exprs, expr_) ?
 			}
 		}
+		ast.StructInit {
+			fields := val.fields.clone()
+			for field in fields {
+				p.check_undefined_variables(exprs, field.expr) ?
+			}
+		}
 		else {}
 	}
 }