Higher-ranked lifetimes captured by `impl Trait` result in too many errors in 2024 edition

[estebank]

Code

// Slightly modified from tests/ui/impl-trait/issues/issue-54895.rs
trait Trait<'a> {
    type Out;
    fn call(&'a self) -> Self::Out;
}

struct X(());

impl<'a> Trait<'a> for X {
    type Out = ();
    fn call(&'a self) -> Self::Out {
        ()
    }
}

fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
    //~^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
    //[edition2024]~^^ ERROR `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
    X(())
}

fn main() {
    let _ = f();
}

Current output

error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:44
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                                            ^^^^^^^^^^^^^^^^^^^^ `impl Trait` implicitly captures all lifetimes in scope
   |
note: lifetime declared here
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:24
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                        ^^

error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:44
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                                            ^^^^^^^^^^^^^^^^^^^^ `impl Trait` implicitly captures all lifetimes in scope
   |
note: lifetime declared here
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:20
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                    ^^

error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:57
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                                                         ^^
   |
note: lifetime declared here
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:20
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                    ^^

error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:62
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                                                              ^^
   |
note: lifetime declared here
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:24
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                        ^^

error: aborting due to 4 previous errors

Desired output

error[E0657]: `impl Trait` cannot capture higher-ranked lifetime from outer `impl Trait`
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:44
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                                            ^^^^^^^^^^   ^^   ^^
   |                                            |
   |                                            `impl Trait` implicitly captures all lifetimes in scope
note: captured lifetimes declared here
  --> tests/ui/impl-trait/issues/issue-54895.rs:18:24
   |
18 | fn f() -> impl for<'a, 'b> Trait<'a, Out = impl Sized + 'a + 'b> {
   |                    ^^  ^^

error: aborting due to 1 previous error

Rationale and extra context

In the example we're emitting 4 errors when a single one would suffice. In ediiton 2024, implicit captures cause two errors per lifetime, one pointing at the whole impl Trait + 'lt and another pointing at the 'lt. This gets repeated for each lifetime involved. Deduplication doesn't happen first because the primary span is different, and later because the "lifetime declared here" span points to a different one each time. It might be reasonable to not mention the implicit lifetime captures if there's an explicit one causing an error already.

Other cases

Rust Version

rustc 1.90.0-dev
binary: rustc
commit-hash: unknown
commit-date: unknown
host: x86_64-unknown-linux-gnu
release: 1.90.0-dev
LLVM version: 20.1.7

Anything else?

Noticed while working on #142255.