rustdoc: link to stable/beta docs consistently in documentation

 ## User-facing changes

- Intra-doc links to primitives that currently go to rust-lang.org/nightly/std/primitive.x.html will start going to channel that rustdoc was built with. Nightly will continue going to /nightly; Beta will link to /beta; stable compilers will link to /1.52.1 (or whatever version they were built as).
- Cross-crate links from std to core currently go to /nightly unconditionally. They will start going to /1.52.0 on stable channels (but remain the same on nightly channels).
- Intra-crate links from std to std (or core to core) currently go to the same URL they are hosted at; they will continue to do so. Notably, this is different from everything else because it can preserve the distinction between /stable and /1.52.0 by using relative links.

Note that "links" includes both intra-doc links and rustdoc's own
automatically generated hyperlinks.

 ## Implementation changes

- Update the testsuite to allow linking to /beta and /1.52.1 in docs
- Use an html_root_url for the standard library that's dependent on the channel

  This avoids linking to nightly docs on stable.

- Update rustdoc to use channel-dependent links for primitives from an
  unknown crate

- Set DOC_RUST_LANG_ORG_CHANNEL from bootstrap to ensure it's in sync
- Include doc.rust-lang.org in the channel

1 files changed, 14 insertions, 14 deletions

diff --git a/src/test/rustdoc/intra-doc/generic-params.rs b/src/test/rustdoc/intra-doc/generic-params.rs
index 1de6410f10c..fbc9fc6a9bc 100644
--- a/src/test/rustdoc/intra-doc/generic-params.rs
+++ b/src/test/rustdoc/intra-doc/generic-params.rs
@@ -5,40 +5,40 @@
 //! Here's a link to [`Vec<T>`] and one to [`Box<Vec<Option<T>>>`].
 //! Here's a link to [`Iterator<Box<T>>::Item`].
 //!
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html"]' 'Vec<T>'
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html"]' 'Box<Vec<Option<T>>>'
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/core/iter/traits/iterator/trait.Iterator.html#associatedtype.Item"]' 'Iterator<Box<T>>::Item'
+// @has foo/index.html '//a[@href="{{channel}}/alloc/vec/struct.Vec.html"]' 'Vec<T>'
+// @has foo/index.html '//a[@href="{{channel}}/alloc/boxed/struct.Box.html"]' 'Box<Vec<Option<T>>>'
+// @has foo/index.html '//a[@href="{{channel}}/core/iter/traits/iterator/trait.Iterator.html#associatedtype.Item"]' 'Iterator<Box<T>>::Item'
 
 //! And what about a link to [just `Option`](Option) and, [with the generic, `Option<T>`](Option<T>)?
 //!
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html"]' 'just Option'
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html"]' 'with the generic, Option<T>'
+// @has foo/index.html '//a[@href="{{channel}}/core/option/enum.Option.html"]' 'just Option'
+// @has foo/index.html '//a[@href="{{channel}}/core/option/enum.Option.html"]' 'with the generic, Option<T>'
 
 //! We should also try linking to [`Result<T, E>`]; it has *two* generics!
 //! And [`Result<T, !>`] and [`Result<!, E>`].
 //!
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html"]' 'Result<T, E>'
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html"]' 'Result<T, !>'
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html"]' 'Result<!, E>'
+// @has foo/index.html '//a[@href="{{channel}}/core/result/enum.Result.html"]' 'Result<T, E>'
+// @has foo/index.html '//a[@href="{{channel}}/core/result/enum.Result.html"]' 'Result<T, !>'
+// @has foo/index.html '//a[@href="{{channel}}/core/result/enum.Result.html"]' 'Result<!, E>'
 
 //! Now let's test a trickier case: [`Vec::<T>::new`], or you could write it
 //! [with parentheses as `Vec::<T>::new()`][Vec::<T>::new()].
 //! And what about something even harder? That would be [`Vec::<Box<T>>::new()`].
 //!
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html#method.new"]' 'Vec::<T>::new'
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html#method.new"]' 'with parentheses as Vec::<T>::new()'
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html#method.new"]' 'Vec::<Box<T>>::new()'
+// @has foo/index.html '//a[@href="{{channel}}/alloc/vec/struct.Vec.html#method.new"]' 'Vec::<T>::new'
+// @has foo/index.html '//a[@href="{{channel}}/alloc/vec/struct.Vec.html#method.new"]' 'with parentheses as Vec::<T>::new()'
+// @has foo/index.html '//a[@href="{{channel}}/alloc/vec/struct.Vec.html#method.new"]' 'Vec::<Box<T>>::new()'
 
 //! This is also pretty tricky: [`TypeId::of::<String>()`].
 //! And this too: [`Vec::<std::error::Error>::len`].
 //!
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/core/any/struct.TypeId.html#method.of"]' 'TypeId::of::<String>()'
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html#method.len"]' 'Vec::<std::error::Error>::len'
+// @has foo/index.html '//a[@href="{{channel}}/core/any/struct.TypeId.html#method.of"]' 'TypeId::of::<String>()'
+// @has foo/index.html '//a[@href="{{channel}}/alloc/vec/struct.Vec.html#method.len"]' 'Vec::<std::error::Error>::len'
 
 //! We unofficially and implicitly support things that aren't valid in the actual Rust syntax, like
 //! [`Box::<T>new()`]. We may not support them in the future!
 //!
-// @has foo/index.html '//a[@href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html#method.new"]' 'Box::<T>new()'
+// @has foo/index.html '//a[@href="{{channel}}/alloc/boxed/struct.Box.html#method.new"]' 'Box::<T>new()'
 
 //! These will be resolved as regular links:
 //! - [`this is <invalid syntax> first`](https://www.rust-lang.org)