Implementation is not general enough error with no context

Code

use std::{any::Any, marker::PhantomData};

pub struct HasDropImpl;
impl core::ops::Drop for HasDropImpl {
    fn drop(&mut self) {}
}

pub struct Wrapper<Context = dyn Any>
where
    Context: ObjectMarker + ?Sized,
{
    raw: HasDropImpl,
    _param: PhantomData<Context>,
}

unsafe impl<C> Send for Wrapper<C> where C: ObjectMarker + ?Sized {}

pub(crate) trait ObjectMarker {}
impl ObjectMarker for dyn Any {}

fn fails() -> Result<(), Wrapper> {
    Ok(())
}

async fn fut1() {}

fn main() {
    let fut = async {
        let _across_await = fails();
        fut1().await;
    };

    require_send(fut);
}

fn require_send<F>(_: F)
where
    F: Future + Send,
{
}

Current output

error: implementation of `ObjectMarker` is not general enough
  --> src/main.rs:33:5
   |
33 |     require_send(fut);
   |     ^^^^^^^^^^^^^^^^^ implementation of `ObjectMarker` is not general enough
   |
   = note: `(dyn Any + '0)` must implement `ObjectMarker`, for any lifetime `'0`...
   = note: ...but `ObjectMarker` is actually implemented for the type `(dyn Any + 'static)`

Desired output

Rationale and extra context

This is a minimization from the rootcause library. The original error was exactly the same, with no more information than this.

Other cases

Rust Version

rustc 1.93.0-nightly (27b076af7 2025-11-21)
binary: rustc
commit-hash: 27b076af7e3e7a363975443d81dfa9ecee5a74ec
commit-date: 2025-11-21
host: x86_64-unknown-linux-gnu
release: 1.93.0-nightly
LLVM version: 21.1.5

Anything else?

No response

Reproduce the minimized example in src/main.rs with rustc 1.93.0-nightly and inspect the emitted “implementation ... not general enough” diagnostic. Trace the compiler entry point responsible for this diagnostic and determine what context is available for this case. Done means the same example produces a more informative diagnostic or an explicitly improved result, with regression coverage added where the compiler tests permit.