delete mode 100644 test/behavior/empty_union.zig
 create mode 100644 test/cases/compile_errors/empty_extern_union.zig
 create mode 100644 test/cases/compile_errors/empty_packed_union.zig
 create mode 100644 test/cases/compile_errors/initialize_empty_union.zig
 create mode 100644 test/cases/compile_errors/sizeof_alignof_empty_union.zig