autofree: fix optional returns

vlib/v/gen/c/cgen.v

@@ -4664,6 +4664,7 @@ fn (mut g Gen) return_statement(node ast.Return) {
 		if optional_none || is_regular_option || node.types[0] == ast.error_type_idx {
 			g.write('return ')
 			g.gen_optional_error(g.fn_decl.return_type, node.exprs[0])
+			// g.writeln('; /*ret1*/')
 			g.writeln(';')
 			return
 		}
@@ -4778,6 +4779,7 @@ fn (mut g Gen) return_statement(node ast.Return) {
 				}
 			}
 			g.writeln(' }, (Option*)(&$opt_tmp), sizeof($styp));')
+			g.autofree_scope_vars(node.pos.pos - 1, node.pos.line_nr, true)
 			g.writeln('return $opt_tmp;')
 			return
 		}

vlib/v/tests/valgrind/1.strings_and_arrays.v

@@ -353,6 +353,8 @@ fn parse_header0(s string) ?string {
 		return error('missing colon in header')
 	}
 	words := s.split_nth(':', 2)
+	// x := words[0]
+	// return x
 	return words[0]
 }
 
@@ -386,7 +388,7 @@ fn main() {
 	s2 := return_sb_str()
 	// free_map()
 	// loop_map()
-	// advanced_optionals()
+	advanced_optionals()
 	free_array_except_returned_element()
 	println('end')
 }