IIFE false positive when temporary lifetimes are involved

Summary

The format_args! macro creates temporaries dropped at the end of the expression, so

let x = format_args!("");

is almost always unusable. An IIFE can be used to extend the temporary lifetime to the entirety of the IIFE, allowing format_args! to be used for factoring out large format_args!.

This typically isn't necessary, as you an just nest format_args! directly, but is useful for cases where a fmt;:Arguments may be used in multiple places, e.g.

(|message| {
    #[cfg(debug_assertions)]
    panic!("{}", message);
    #[cfg(not(debug_assertions)]
    eprintln!("{}; attempting to continue...", message);
})(format_args!("big message that formats some locals and would be annoying to duplicate multiple times"));

Lint Name

clippy::redundant_closure_call

Reproducer

I tried this code:

pub fn main() {
    let a = 2;
    let b = 3;
    let c = a + b;

    (|equasion| {
        println!("With Rust, we can know that {equasion}!");
    })(format_args!("{a} + {b} = {c}"));
}

I saw this happen:

warning: try not to call a closure in the expression where it is declared
 --> src/main.rs:6:5
  |
6 | /     (|equasion| {
7 | |         println!("With Rust, we can know that {equasion}!");
8 | |     })(format_args!("{a} + {b} = {c}"));
  | |_______________________________________^
  |
  = note: `#[warn(clippy::redundant_closure_call)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure_call

I expected to see this happen:

No warnings (as with IIFE-for-try) because replacing the IIFE with a let binding changes temporary lifetimes to make the code no longer compile.

Version

rustc 1.61.0-nightly (76d770ac2 2022-04-02)
binary: rustc
commit-hash: 76d770ac21d9521db6a92a48c7b3d5b2cc535941
commit-date: 2022-04-02
host: x86_64-pc-windows-msvc
release: 1.61.0-nightly
LLVM version: 14.0.0

Start by locating the implementation and tests for the clippy::redundant_closure_call lint, then run the Rust reproducer from the issue to confirm the warning. Compare the format_args! IIFE case with an ordinary redundant closure call; done means the lifetime-preserving case is accepted without weakening the lint for cases that remain redundant.