Intra-doc links do not work in markdown files

[jyn514]

I tried this code:

# Hello

Link to [std::process::Command]

I expected to see this happen: Rustdoc generates a link to https://doc.rust-lang.org/std/process/struct.Command.html

Instead, this happened: Rustdoc writes the literal text [std::process::Command]

This might be a little tricky because there is no scope to resolve in. I think ideally this would have the same scope as an empty crate with only the std injects (extern crate std; use std::prelude::v1::*;).

Noticed this in #77971.

Meta

rustdoc --version:

rustdoc 1.49.0-nightly (91a79fb29 2020-10-07)

[jyn514]

#99466 came up with a fascinating solution: Add -L target/debug/deps so that rustdoc can still load the crates even when running doctests.

That doesn't actually work for intra-doc links because rustdoc runs in a different mode (that doesn't run the compiler internally) but I think it should be feasible to start loading crates when rendering markdown files :) which would make this exactly parallel to how rust source code works.