See https://is.gd/FO2qVB. Code: ``` rust fn foo<T>(_t: T) where for<'a> &'a T: for<'b> std::ops::Mul<&'b T, Output=T> {} ``` Compile output: ``` Span { lo: BytePos(38), hi: BytePos(76), expn_id: ExpnId(4294967295) } error: nested quantification of lifetimes [E0316] --> <anon>:1:39 |> 1 |> fn foo<T>(_t: T) where for<'a> &'a T: for<'b> std::ops::Mul<&'b T, Output=T> {} |> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: aborting due to previous error ``` Note the `Span { ... }`.