overflow evaluating the requirement `impl ListString: std::marker::Freeze`

[NilSet]

This code fails to compile in an interesting and unhelpful way, taking about internal traits and giving no line numbers.

https://play.rust-lang.org/?gist=a6eb10c5a6350a9c6fbf8e4af87d98d2&version=nightly

[kennytm]

The current error doesn't mention std::marker::Freeze anymore.

rustc version: 1.23.0-nightly (2017-11-15 fa26421f56e385b1055e65b29a55b36bb2eae23e).

   Compiling playground v0.0.1 (file:///playground)
error[E0275]: overflow evaluating the requirement `<<<<<<T as ListString>::Tail as ListString>::Tail as ListString>::Tail as ListString>::Tail as ListString>::Tail as ListString>::Tail: ListString`
  |
  = help: consider adding a `#![recursion_limit="24"]` attribute to your crate
  = note: required because it appears within the type `Cons<impl ListString>`
  = note: required because it appears within the type `impl ListString`
  = note: required because it appears within the type `Cons<impl ListString>`
  = note: required because it appears within the type `impl ListString`
  = note: required because it appears within the type `Cons<impl ListString>`
  = note: required because it appears within the type `impl ListString`
  = note: required because it appears within the type `Cons<impl ListString>`
  = note: required because it appears within the type `impl ListString`
  = note: required because it appears within the type `Cons<impl ListString>`
  = note: required because it appears within the type `impl ListString`
  = note: required because it appears within the type `Cons<impl ListString>`
  = note: required because it appears within the type `impl ListString`

error: aborting due to previous error

error: Could not compile `playground`.

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