ast: fix generic fn with multiple return (#12971)

vlib/v/ast/table.v

@@ -1056,8 +1056,9 @@ pub fn (mut t Table) find_or_register_multi_return(mr_typs []Type) int {
 	mut cname := 'multi_return'
 	for i, mr_typ in mr_typs {
 		mr_type_sym := t.sym(mr_typ)
-		name += mr_type_sym.name
+		ref, cref := if mr_typ.is_ptr() { '&', 'ref_' } else { '', '' }
-		cname += '_$mr_type_sym.cname'
+		name += '$ref$mr_type_sym.name'
+		cname += '_$cref$mr_type_sym.cname'
 		if i < mr_typs.len - 1 {
 			name += ', '
 		}

vlib/v/tests/generic_fn_multi_return_test.v

@@ -0,0 +1,53 @@
+fn test_generic_fn_multi_return() {
+	mut a1 := GenRef<u32, u32>{32, 99}
+	b1, c1 := a1.generic_reference() or {
+		assert false
+		return
+	}
+	println(b1)
+	assert b1 == 32
+	println(c1)
+	assert *c1 == 99
+
+	mut a2 := GenRef<u64, u64>{322, 999}
+	b2, c2 := a2.generic_reference() or {
+		assert false
+		return
+	}
+	println(b2)
+	assert b2 == 322
+	println(c2)
+	assert *c2 == 999
+
+	mut a3 := GenRef<i32, u64>{22, 77}
+	b3, c3 := a3.generic_reference() or {
+		assert false
+		return
+	}
+	println(b3)
+	assert b3 == 22
+	println(c3)
+	assert *c3 == 77
+
+	mut a4 := GenRef<f64, u64>{2.2, 777}
+	b4, c4 := a4.generic_reference() or {
+		assert false
+		return
+	}
+	println(b4)
+	assert b4 == 2.2
+	println(c4)
+	assert *c4 == 777
+}
+
+struct GenRef<K, V> {
+	key K
+	val V
+}
+
+fn (mut self GenRef<K, V>) generic_reference() ?(K, &V) {
+	if false {
+		return none
+	}
+	return self.key, unsafe { &self.val }
+}