Static rustc_lint_defs::builtin::UNUSED_MACRO_RULES

pub static UNUSED_MACRO_RULES: &Lint

The unused_macro_rules lint detects macro rules that were not used.

Note that the lint is distinct from the unused_macros lint, which fires if the entire macro is never called, while this lint fires for single unused rules of the macro that is otherwise used. unused_macro_rules fires only if unused_macros wouldn’t fire.

Example

#[warn(unused_macro_rules)]
macro_rules! unused_empty {
    (hello) => { println!("Hello, world!") }; // This rule is unused
    () => { println!("empty") }; // This rule is used
}

fn main() {
    unused_empty!(hello);
}

{{produces}}

Explanation

Unused macro rules may signal a mistake or unfinished code. Furthermore, they slow down compilation. Right now, silencing the warning is not supported on a single rule level, so you have to add an allow to the entire macro definition.

If you intended to export the macro to make it available outside of the crate, use the macro_export attribute.