1 /// A simple static assertion macro.
3 #[cfg_attr(bootstrap, allow_internal_unstable(type_ascription, underscore_const_names))]
4 #[cfg_attr(not(bootstrap), allow_internal_unstable(type_ascription))]
5 macro_rules! static_assert {
7 // Use the bool to access an array such that if the bool is false, the access
10 const _: () = [()][!($test: bool) as usize];
14 /// Type size assertion. The first argument is a type and the second argument is its expected size.
16 #[cfg_attr(bootstrap, allow_internal_unstable(underscore_const_names))]
17 macro_rules! static_assert_size {
18 ($ty:ty, $size:expr) => {
19 const _: [(); $size] = [(); ::std::mem::size_of::<$ty>()];