G.FUD.05 Don't always specify #[inline(always)] for function

[Level] Advice

[Description]

inline could imporve performance, but also increase compilation time and size. You have to make a tradeoff among Performance, Compilation time and Compilation size in Rust, and it is recommended to use inline on demand.

[Bad Case]

#![allow(unused)]
#![warn(clippy::inline_always)]

fn main() {
// Not Good
#[inline(always)]
fn not_quite_hot_code(..) { ... }
}

[Exception]

Use inline on demand. i.e. it is obvious that one function is called frequently, and you could use inline for it to improve performance.

#![allow(unused)]
fn main() {
// Good: that function is often called for recycle buffer memory, so use `inline` maximize its performance.
pub fn buf_recycle(buf_id: usize) {
    // ...
}
}

[Lint Check]