Macro declare_trace

macro_rules! declare_trace {
    ($($(#[$attr:meta])* $pub:vis unsafe fn $name:ident($($argname:ident : $argtyp:ty),* $(,)?);)*) => { ... };
}

Declare the Rust entry point for a tracepoint.

This macro generates an unsafe function that calls into C, and its safety requirements will be whatever the relevant C code requires. To document these safety requirements, you may add doc-comments when invoking the macro.