Macro trace_call 

macro_rules! trace_call {
    ($trace:expr, $node:expr, $function:literal, $operation:expr) => { ... };
}

Record one logical function invocation with its source location. 用一条宏调用记录一次逻辑函数调用，并保留源码位置。

The closure is deliberately the only required wrapper. It keeps the tracing boundary explicit, works on stable Rust, and does not introduce a trait object or a global callback into the hot path. 闭包是唯一必须写出的边界，兼容 stable Rust；不会引入 trait object， 也不会在热路径上增加全局回调。