/// This item is known to rustdoc, but from a crate that does not have documentation generated.
///
/// This can only happen for non-local items.
+ ///
+ /// # Example
+ ///
+ /// Crate `a` defines a public trait and crate `b` – the target crate that depends on `a` –
+ /// implements it for a local type.
+ /// We document `b` but **not** `a` (we only _build_ the latter – with `rustc`):
+ ///
+ /// ```sh
+ /// rustc a.rs --crate-type=lib
+ /// rustdoc b.rs --crate-type=lib --extern=a=liba.rlib
+ /// ```
+ ///
+ /// Now, the associated items in the trait impl want to link to the corresponding item in the
+ /// trait declaration (see `html::render::assoc_href_attr`) but it's not available since their
+ /// *documentation (was) not built*.
DocumentationNotBuilt,
/// This can only happen for non-local items when `--document-private-items` is not passed.
Private,