Macro static_assert

macro_rules! static_assert {
    ($condition:expr $(,$arg:literal)?) => { ... };
}

Static assert (i.e. compile-time assert).

Similar to C11 _Static_assert and C++11 static_assert.

An optional panic message can be supplied after the expression. Currently only a string literal without formatting is supported due to constness limitations of the assert! macro.

The feature may be added to Rust in the future: see RFC 2790.

Examples

static_assert!(42 > 24);
static_assert!(core::mem::size_of::<u8>() == 1);

const X: &[u8] = b"bar";
static_assert!(X[1] == b'a');

const fn f(x: i32) -> i32 {
    x + 2
}
static_assert!(f(40) == 42);
static_assert!(f(40) == 42, "f(x) must add 2 to the given input.");