message: Add a proper Debug for FrozenList
  Summary: Previously it debug printed without its contents, which made it hard to debug.
diff: @@ -22,7 +22,7 @@ use std::{
  cell::Cell,
  cmp,
  cmp::Ordering,
  - fmt::{self, Debug, Display},
  + fmt::{self, Debug, Display, Formatter},
  intrinsics::{likely, unlikely},
  marker::PhantomData,
  ops::Deref,
  @@ -60,7 +60,7 @@ pub struct List<'v> {
  }
  /// Define the list type. See [`List`] and [`FrozenList`] as the two possible representations.
  -#[derive(Debug, AnyLifetime)]
  +#[derive(AnyLifetime)]
  #[repr(C)]
  pub struct FrozenList {
  len: usize,
  @@ -68,6 +68,14 @@ pub struct FrozenList {
  content: [FrozenValue; 0],
  }
  +impl<'v> Debug for FrozenList {
  + fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
  + f.debug_struct("FrozenList")
  + .field("content", &self.content())
  + .finish()
  + }
  +}
  +
  impl ListGen<FrozenList> {
  pub fn offset_of_content() -> usize {
  memoffset::offset_of!(FrozenList, content)
  