Intra-doc links cannot link to associated methods on type aliases.

[jonhoo]

I tried this code:

#[warn(rustdoc::all)]

pub struct Foo<C>(C);

impl<C> Foo<C> {
    pub fn new() -> Self {
        todo!()
    }
}

/// [`Bar::new`]
pub type Bar<C> = Foo<C>;

I expected to see this happen: Bar::new should be a link to Foo::new.

Instead, this happened: Bar::new was not turned into a link, and the compiler gave this warning:

warning: unresolved link to `Bar::new`
  --> src/lib.rs:11:6
   |
11 | /// [`Bar::new`]
   |      ^^^^^^^^^^ the type alias `Bar` has no associated item named `new`
   |
   = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default

warning: 1 warning emitted

I'm guessing that this isn't implemented because the forwarding may not always be obvious such as if there are multiple fn new for Foo for different values of C. But it'd be nice if it did work when there aren't and the choice is "clear".

EDIT: Though on second thought, that should also be an issue for

/// [`Foo::new`]

on Foo, so I feel like if that works this should also work.

Meta

rustc --version --verbose:

rustc 1.52.1 (9bc8c42bb 2021-05-09)
binary: rustc
commit-hash: 9bc8c42bb2f19e745a63f3445f1ac248fb015e53
commit-date: 2021-05-09
host: x86_64-apple-darwin
release: 1.52.1
LLVM version: 12.0.0

The same issue is present on nightly.

[jonhoo]

This is a simplified variant of #85960.

[inquisitivecrystal]

@rustbot label +A-intra-doc-links +T-rustdoc

[LeSeulArtichaut]

This can give some pretty surprising results:

pub struct Foo;

/// You should really try [`Self::bar`]
pub type Bar = Foo;

impl Bar {
    pub fn bar() {}
}

fails with

warning: unresolved link to `Bar::bar`
 --> test.rs:3:28
  |
3 | /// You should really try [`Self::bar`]
  |                            ^^^^^^^^^^^ the type alias `Bar` has no associated item named `bar`
  |
  = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default

warning: 1 warning emitted