Bad parse error on token sequences `safe unsafe` and `unsafe safe` (before extern fns)

[ionicmc-rs]

Code

safe unsafe extern "C" fn foo() {
   // ...
}

Current output

help: unsafe comes before safe: `unsafe safe`

Desired output

error: safe is invalid outside of `unsafe extern` blocks
help: extern functions are safe by default

Rationale and extra context

this is a follow-up to my previous issue #133586, for more info you can visit it or see the PR (#133618 (closed))

Other cases

unsafe safe extern "C" fn foo() {} // safe is recognised as an identifier, and suggests putting a block around it

Rust Version

rustc 1.82.0 (f6e511eec 2024-10-15)
binary: rustc
commit-hash: f6e511eec7342f59a25f7c0534f1dbea00d01b14
commit-date: 2024-10-15
host: x86_64-unknown-linux-gnu
release: 1.82.0
LLVM version: 19.1.1

Anything else?

The same happens with nightly releases

[ionicmc-rs]

This issue has been combined into one with #133586 at #134580