Note: As of Rust 1.57 this crate is superseded by native support for panic! in const contexts. Only consider using this crate if you care about supporting compilers between 1.31 and 1.57. |
This crate provide macros assertions who can be used in const function.
```rust const fn myconstfn(x: u8) -> u8 { cfn_assert!(x < 5); x + 1 }
const CONST: u8 = myconst_fn(1);
fn main() { let var = myconst_fn(2); } ```
The function below panic when running :
rust
fn fail() {
let _var = my_const_fn(6); //thread 'main' panicked at 'index out of bounds: the len is 1 but the index is 1'
}
And this code don't compile :
rust
const _CONST: u8 = my_const_fn(6); //~ ERROR any use of this value will cause an error
Available macros are cfn_assert, cfn_assert_eq, cfn_assert_ne, cfn_debug_assert, cfn_debug_assert_eq and cfn_debug_assert_ne.
This crate is available
on crates.io and can be used by
adding the following to your project's
Cargo.toml:
toml
[dependencies]
const_fn_assert = "0.1"
and this to your crate root (main.rs or lib.rs):
```rust
extern crate constfnassert; ```