Macro build_assert::build_assert

macro_rules! build_assert {
    ($cond:expr $(,)?) => { ... };
    ($cond:expr, $($arg:tt)+) => { ... };
}

Asserts that a boolean expression is true at build-time.

In release mode, if the expression is evaluated to false, or the compiler or optimizer cannot ensure that the expression is evaluated to true, this macro will stop the compilation process.

In debug mode, if the expression is evaluated to false, this macro will panic.

Examples

fn foo<const N: usize>() {
  build_assert!(N.is_power_of_two(), "N is not a power of two");
}

foo::<16>(); // Fine.

foo::<15>(); // Fails to compile in release mode, panics in debug mode.