Macro const_warn 

macro_rules! const_warn {
    ($msg:literal $(,)?) => { ... };
    (if $cond:expr, $msg:literal $(,)?) => { ... };
    (%if $cond:expr, $name:ident, $msg:literal $(,)?) => { ... };
}

⌗ 🐛 Emits a compile-time warning with a provided message.

---

^{📍 code/util}

---

Example

fn main() {
    const_warn!("hello warning!");
    const_warn!(if size_of::<u8>() == 1, "byte alert!!");
}

That may look as follows:

warning: use of deprecated associated constant `main::_::__::<true>::WARNING`: hello warning!
 --> src/main.rs:3:5
  |
3 |     const_warn!("hello warning!");
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(deprecated)]` on by default
  = note: this warning originates in the macro `$crate::const_warn` which comes from the expansion of the macro `const_warn` (in Nightly builds, run with -Z macro-backtrace for more info)

warning: use of deprecated associated constant `main::_::__::<true>::WARNING`: byte alert!!
 --> src/main.rs:4:5
  |
4 |     const_warn!(if size_of::<u8>() == 1, "byte alert!!");
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  ...