Macro konst::assertc_ne

macro_rules! assertc_ne {
    ($left:expr, $right:expr $(, $($fmt:tt)* )? ) => { ... };
}

Available on crate feature cmp only.

For asserting that two values are unequal.

examples below

This macro is only evaluated at compile-time if used in a context that requires it (eg: in the expression assigned to a const _: () = )

Formatting

This uses the same syntax for formatting arguments as const_panic::concat_panic.

By default, this only supports primitive types as arguments, to format arrays or custom types you must enable const_panic’s "non_basic" feature.

To pass user-defined types, they must implement both of these traits as described in their docs:

• konst::cmp::ConstCmp
• const_panic::fmt::PanicFmt

Examples

Unique strings

assert_eq!(NAMES, ["bob", "matt", "rob"]);

const NAMES: &[&str] = assert_unique(&["bob", "matt", "rob"]);

#[track_caller]
const fn assert_unique<'a, 'b>(names: &'a [&'b str]) -> &'a [&'b str] {
    konst::for_range!{x in 0..names.len() =>
        konst::for_range!{y in 0..names.len() =>
            if x == y { continue }
            konst::assertc_ne!{
                names[x],
                names[y],
                "equal names at index `", x, "` and `", y, "`"
            }
        }
    }
    names
}

If the argument had repeated strings, this would be the error:

error[E0080]: evaluation of constant value failed
 --> src/macros/assert_macros.rs:126:24
  |
6 | const NAMES: &[&str] = assert_unique(&["bob", "matt", "rob", "rob"]);
  |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at '
assertion failed: LEFT != RIGHT
 left: `"rob"`
right: `"rob"`
: equal names at index `2` and `3`', src/macros/assert_macros.rs:6:24