checker: check method args

vlib/eventbus/eventbus_test.v

@@ -28,6 +28,6 @@ fn test_eventbus(){
 	assert !eb.subscriber.is_subscribed("on_test")
 }
 
-fn on_test(sender voidptr, ev &EventData) {
+fn on_test(sender voidptr, ev &EventData, x voidptr) {
 	assert ev.data == "hello"
 }

vlib/v/checker/checker.v

@@ -658,17 +658,28 @@ pub fn (mut c Checker) call_method(call_expr mut ast.CallExpr) table.Type {
 		// call_expr.args << method.args[0].typ
 		// call_expr.exp_arg_types << method.args[0].typ
 		for i, arg in call_expr.args {
-			c.expected_type = if method.is_variadic && i >= method.args.len - 1 {
+			exp_arg_typ := if method.is_variadic && i >= method.args.len - 1 {
 				method.args[method.args.len - 1].typ
 			} else {
 				method.args[i + 1].typ
 			}
-			arg_typ := c.expr(arg.expr)
-			call_expr.args[i].typ = arg_typ
-			if method.is_variadic && arg_typ.flag_is(.variadic) && call_expr.args.len - 1 >
+			c.expected_type = exp_arg_typ
+			got_arg_typ := c.expr(arg.expr)
+			call_expr.args[i].typ = got_arg_typ
+			if method.is_variadic && got_arg_typ.flag_is(.variadic) && call_expr.args.len - 1 >
 				i {
 				c.error('when forwarding a varg variable, it must be the final argument', call_expr.pos)
 			}
+			if !c.table.check(got_arg_typ, exp_arg_typ) {
+				got_arg_sym := c.table.get_type_symbol(got_arg_typ)
+				exp_arg_sym := c.table.get_type_symbol(exp_arg_typ)
+				// str method, allow type with str method if fn arg is string
+				if exp_arg_sym.kind == .string && got_arg_sym.has_method('str') {
+					continue
+				}
+				c.error('cannot use type `$got_arg_sym.str()` as type `$exp_arg_sym.str()` in argument ${i+1} to `${left_type_sym.name}.$method_name`',
+					call_expr.pos)
+			}
 		}
 		// TODO: typ optimize.. this node can get processed more than once
 		if call_expr.expected_arg_types.len == 0 {

vlib/v/table/table.v

@@ -529,8 +529,15 @@ pub fn (t &Table) check(got, expected Type) bool {
 	if got_type_sym.kind == .function && exp_type_sym.kind == .function {
 		got_info := got_type_sym.info as FnType
 		exp_info := exp_type_sym.info as FnType
-		if got_info.func.signature() == exp_info.func.signature() {
-			return true
+		if got_info.func.args.len == exp_info.func.args.len {
+			mut matching := false
+			for i, arg in got_info.func.args {
+				exp_arg := exp_info.func.args[i]
+				matching = arg.typ.idx() == exp_arg.typ.idx() || exp_arg.typ == table.voidptr_type
+			}
+			if matching {
+				return true
+			}
 		}
 	}
 	if got_idx != exp_idx {