ices/63031.rs: fixed with no errors

[github-actions]

Issue: rust-lang/rust#63031

trait Lf<'a> { type Type; }

struct F32;
impl<'a> Lf<'a> for F32 { type Type = f32; }

struct RefI32;
impl<'a> Lf<'a> for RefI32 { type Type = &'a i32; }

fn add_closure<T: for<'b> Lf<'b> + 'static>(v: &mut Vec<Box<for<'a> FnMut(<T as Lf<'a>>::Type)>>) {
    v.push(Box::new(move |_| {
    }));
}

fn main() {
    // bug? compiler can't seem to deduce <F32 as Lf<'a>>::Type == f32 nor <RefI32 as Lf<'a>>::Type == &'a i32
    let mut v1 = Vec::<Box<for<'a> FnMut(<F32 as Lf<'a>>::Type)>>::new();
    let mut v2 = Vec::<Box<for<'a> FnMut(<RefI32 as Lf<'a>>::Type)>>::new();
    add_closure::<F32>(&mut v1);
    add_closure::<RefI32>(&mut v2);
}

=== stdout ===
=== stderr ===
warning: trait objects without an explicit `dyn` are deprecated
 --> /home/runner/work/glacier/glacier/ices/63031.rs:9:61
  |
9 | fn add_closure<T: for<'b> Lf<'b> + 'static>(v: &mut Vec<Box<for<'a> FnMut(<T as Lf<'a>>::Type)>>) {
  |                                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn for<'a> FnMut(<T as Lf<'a>>::Type)`
  |
  = note: `#[warn(bare_trait_objects)]` on by default
  = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
  = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>

warning: trait objects without an explicit `dyn` are deprecated
  --> /home/runner/work/glacier/glacier/ices/63031.rs:16:28
   |
16 |     let mut v1 = Vec::<Box<for<'a> FnMut(<F32 as Lf<'a>>::Type)>>::new();
   |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn for<'a> FnMut(<F32 as Lf<'a>>::Type)`
   |
   = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>

warning: trait objects without an explicit `dyn` are deprecated
  --> /home/runner/work/glacier/glacier/ices/63031.rs:17:28
   |
17 |     let mut v2 = Vec::<Box<for<'a> FnMut(<RefI32 as Lf<'a>>::Type)>>::new();
   |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn for<'a> FnMut(<RefI32 as Lf<'a>>::Type)`
   |
   = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>

warning: 3 warnings emitted

==============