error: lifetime may not live long enough
  --> $DIR/issue-75777.rs:11:5
   |
LL | fn inject<'a, Env: 'a, A: 'a + Send>(v: A) -> Box<dyn FnOnce(&'a Env) -> BoxFuture<'a, A>> {
   |           -- lifetime `'a` defined here
LL |     let fut: BoxFuture<'a, A> = Box::pin(future::ready(v));
LL |     Box::new(move |_| fut)
   |     ^^^^^^^^^^^^^^^^^^^^^^ returning this value requires that `'a` must outlive `'static`

error: aborting due to 1 previous error