Error on bounds for unused lifetime

The following fails to build:

struct Foo<'a, 'b: 'a, 'c: 'a>(&'a mut &'a (), &'b (), &'c ());
fn with_foo<'b>(_f: impl FnOnce(Foo<'_, 'b, '_>)) {}

struct Bar;
impl Bar {
    fn baz<'a>(&'a self, _foo: Foo<'a, '_, '_>) {}

    fn call_baz<'b>(&'b self) {
        with_foo::<'b>(|foo| self.baz(foo))
    }
}

error[E0521]: borrowed data escapes outside of method
 --> src/lib.rs:9:30
  |
8 |     fn call_baz<'b>(&'b self) {
  |                 --  -------- `self` is a reference that is only valid in the method body
  |                 |
  |                 lifetime `'b` defined here
9 |         with_foo::<'b>(|foo| self.baz(foo))
  |                              ^^^^^^^^^^^^^
  |                              |
  |                              `self` escapes the method body here
  |                              argument requires that `'b` must outlive `'static`

For more information about this error, try `rustc --explain E0521`.
error: could not compile `playground` (lib) due to 1 previous error

However, it works if the bounds on 'c argument on the declaration of Foo are changed to either 'c: 'b, or simply an unbounded lifetime 'c. This seems unexpected because 'c: 'b is a stricter bound than 'c: 'a (and 'c is a weaker bound than 'c: 'a). It's even stranger because the 'c lifetime is unused in this example.

This seems to be either a bug, unexpected limitation, or as another user suggested, an NLL regression. I created a post on URLO that has some further discussion.

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rustc --version --verbose:

rustc 1.81.0 (eeb90cda1 2024-09-04)
binary: rustc
commit-hash: eeb90cda1969383f56a2637cbd3037bdf598841c
commit-date: 2024-09-04
host: x86_64-unknown-linux-gnu
release: 1.81.0
LLVM version: 18.1.7

Reproduce the failing lifetime example shown in src/lib.rs using the reported rustc 1.81.0 toolchain, then compare it with the variants where the 'c bound is changed or removed. Trace the compiler's handling of the unused lifetime and determine whether the borrow-checking result is incorrect; done means a justified compiler fix or a documented expected limitation with regression coverage.