Want better error message for attempted hygiene violation

[ijackson]

Code

macro_rules! print_it { {} => { println!("{:?}", it); } }

fn main() {
    let it = ();
    print_it!();
}

Current output

error[E0425]: cannot find value `it` in this scope
 --> src/main.rs:1:50
  |
1 | macro_rules! print_it { {} => { println!("{:?}", it); } }
  |                                                  ^^ not found in this scope
...
5 |     print_it!();
  |     ----------- in this macro invocation

Desired output

error[E0425]: cannot find value `it` in this scope
 --> src/main.rs:1:50
  |
1 | macro_rules! print_it { {} => { println!("{:?}", it); } }
  |                                                  ^^ not found in this scope
...
5 |     print_it!();
  |     ----------- in this macro invocation

help: An identifier with the same name is defined here, but is not accessible due to macro hygiene
4 |    let it = ();
  |        ^^

Rationale and extra context

The current message is quite gaslight-y, I think.

My suggestion would help novices who don't know that hygiene is even a thing.

It would also help experts who are doing something exciting with macros. I found myself confused by this earlier today. (Ref https://gitlab.torproject.org/Diziet/rust-derive-deftly/-/issues/130)

Hygiene things are particularly hard to debug because the hygiene is invisible in cargo expand output etc.

Other cases

I found a whole bunch of exciting tickets relating to macro hygiene. Some of them have scenarios where this new help message would have perhaps helped the user. Eg #46489 #47988

Rust Version

Today's stable on the Rust playground.

https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=1ee109560f0d9e2f216a02e346679f1c