Confusing error when using non-`XID_Start` characters in lifetime names

Code

fn bad_lifetime_name<'🐛>(_: &'🐛 ()) {}

Current output

error: character literal may only contain one codepoint
 --> src/lib.rs:1:22
  |
1 | fn bad_lifetime_name<'🐛>(_: &'🐛 ()) {}
  |                      ^^^^^^^^^^
  |
help: if you meant to write a string literal, use double quotes
  |
1 - fn bad_lifetime_name<'🐛>(_: &'🐛 ()) {}
1 + fn bad_lifetime_name<"🐛>(_: &"🐛 ()) {}
  |

error: unexpected closing delimiter: `)`
 --> src/lib.rs:1:35
  |
1 | fn bad_lifetime_name<'🐛>(_: &'🐛 ()) {}
  |                                     ^ unexpected closing delimiter

Desired output

error: a lifetime name cannot begin with a character that is neither `_` nor a `XID_Start` character

 --> src/lib.rs:1:22
  |
1 | fn bad_lifetime_name<'🐛>(_: &'🐛 ()) {}
  |                       ^--
  |                        help: `\u{1F41B}` is neither `_` nor in `XID_Start`

Rationale and extra context

See also https://doc.rust-lang.org/reference/identifiers.html.
Initially reported at #general > Compiler isn't helpful with invalid lifetimes.

Looks like this recovery path(?) is hit when starting a lifetime name (not including the ') with a non-XID_Start character fails both is_id_start check and ASCII digit check hitting the !can_be_a_lifetime codepath.

https://github.com/rust-lang/rust/blob/c79bbfab78dcb0a72aa3b2bc35c00334b58bfe2e/compiler/rustc_lexer/src/lib.rs#L824-L842

Other cases

Marginally related is loop labels, this complains about "unterminated character literal".

fn main() {
    '🐛: {
        todo!();  
    };
}

Rust Version

$ rustc --version --verbose
rustc 1.87.0 (17067e9ac 2025-05-09)
binary: rustc
commit-hash: 17067e9ac6d7ecb70e50f92c1944e545188d2359
commit-date: 2025-05-09
host: aarch64-unknown-linux-gnu
release: 1.87.0
LLVM version: 20.1.1

Anything else?

No response

Start with the cited recovery path in compiler/rustc_lexer/src/lib.rs around lines 824–842 and reproduce the supplied lifetime-name example. Compare the current and desired diagnostics, then verify that invalid lifetime names report the XID_Start guidance without producing the misleading follow-up errors; the related loop-label case is also noted for consideration.