cgen: fix using pointer as interface receiver

vlib/v/gen/cgen.v

@@ -3429,7 +3429,8 @@ _Interface I_${cctype}_to_Interface(${cctype}* x) {
 	};
 }')
 			methods_struct.writeln('\t{')
-			for method in ityp.methods {
+			st_sym := g.table.get_type_symbol(st)
+			for method in st_sym.methods {
 				// .speak = Cat_speak
 				mut method_call := '${cctype}_${method.name}'
 				if !method.args[0].typ.is_ptr() {

vlib/v/tests/interface_test.v

@@ -7,11 +7,13 @@ struct Cat {
 	breed string
 }
 
-fn (d Cat) name() string {
+fn (mut c Cat) name() string {
+	assert c.breed == 'Persian'
 	return 'Cat'
 }
 
-fn (d Cat) speak(s string) {
+fn (c &Cat) speak(s string) {
+	assert c.breed == 'Persian'
 	assert s == 'Hi !'
 	println('meow')
 }
@@ -32,7 +34,6 @@ fn test_todo() {
 	else{}
 }
 
-
 fn perform_speak(s Animal) {
 	s.speak('Hi !')
 	assert true
@@ -47,9 +48,9 @@ fn perform_speak(s Animal) {
 fn test_perform_speak() {
 	dog := Dog{breed: 'Labrador Retriever'}
 	perform_speak(dog)
-	cat := Cat{}
+	cat := Cat{breed: 'Persian'}
 	perform_speak(cat)
-	perform_speak(Cat{})
+	perform_speak(Cat{breed: 'Persian'})
 	handle_animals([dog, cat])
 	/*
 	f := Foo {
@@ -94,7 +95,6 @@ interface Animal {
 	speak(s string)
 }
 
-
 fn test_interface_array() {
 	mut animals := []Animal{}
 	animals = [ Cat{}, Dog{} ]