Cross crate links can target items which are not rendered in the documentation.
If the item is reexported at a higher level, the destination of the link (a
concatenation of the fully qualified name) may actually lead to nowhere. This
fixes this problem by altering rustdoc to emit pages which redirect to the local
copy of the reexported structure.

cc #14515
Closes #14137

cc #14515

There is currently no way to query all impls for a type from an external crate,
and with primitive types in play this is also quite difficult. Instead of
filtering, just suck in all impls from upstream crates into the local AST, and
have them get stripped later.

This will allow population of all implementations of traits for primitive types,
as well as filling in some corner cases with inlining documentation in other
cases.

This prevents structures like RcBox from showing up in the documentation

This commit adds support in rustdoc to recognize the `#[doc(primitive = "foo")]`
attribute. This attribute indicates that the current module is the "owner" of
the primitive type `foo`. For rustdoc, this means that the doc-comment for the
module is the doc-comment for the primitive type, plus a signal to all
downstream crates that hyperlinks for primitive types will be directed at the
crate containing the `#[doc]` directive.

Additionally, rustdoc will favor crates closest to the one being documented
which "implements the primitive type". For example, documentation of libcore
links to libcore for primitive types, but documentation for libstd and beyond
all links to libstd for primitive types.

This change involves no compiler modifications, it is purely a rustdoc change.
The landing pages for the primitive types primarily serve to show a list of
implemented traits for the primitive type itself.

The primitive types documented includes both strings and slices in a semi-ad-hoc
way, but in a way that should provide at least somewhat meaningful
documentation.

Closes #14474

Type parameters were filled in for some areas, but not all. This commit unifies
the two code paths to fill in type parameters everywhere.

Closes #14508

cc #14462

When inlining documentation across crates, primitive implementors of traits were
not shown. This commit tweaks the infrastructure to treat primitive and
Path-like impls the same way, displaying all implementors everywhere.

cc #14462

The cache is going to be used earlier in the HTML generation process, which
means that it needs to get into TLS as soon as possible.

Instead of one giant function, this breaks it up into several smaller functions
which have explicit dependencies among one another.

There are no code changes as a result of this commit.

This rewrites the example to also be more aligned with
the same example given in the main tutorial.

Renamed `owned_box` to `on_the_heap` to use a consistent
naming across the tutorial and the life time guide.
Also it makes the example easier to grasp.

This rewrites the example to also be more aligned with
the same example given in the main tutorial.

Renamed `owned_box` to `on_the_heap` to use a consistent
naming across the tutorial and the life time guide.
Also it makes the example easier to grasp.

Fixes #14541

By dropping the intermediate vector that holds the relevant candidates
including duplicates and directly building the vector that has the
duplicates removed we can eliminate quite a few allocations. This
reduces the times for type checking by 5-10% (measured with libstd,
libsyntax and librustc).

For some reason, I had this comment in my local tree but not in the
branch I sent with the PR.

By dropping the intermediate vector that holds the relevant candidates
including duplicates and directly building the vector that has the
duplicates removed we can eliminate quite a few allocations. This
reduces the times for type checking by 5-10% (measured with libstd,
libsyntax and librustc).

This was only ever used by rustpkg and is very unmaintained.

[breaking-change]

Fixes #14541

Google have migrated snappy to GitHub.

I removed all remaining deprecated owned vectors from the docs. All example tests pass.

This was only ever used by rustpkg and is very unmaintained.

[breaking-change]

Adds a platform-specific function, `split_paths` to the `os` module. This
function can be used to parse PATH-like environment variables according to
local platform conventions.

Closes #14352.

For some reason, I had this comment in my local tree but not in the
branch I sent with the PR.

Google have migrated snappy to GitHub.

This is part 2 of the saga of renaming the Partial/Total equality and comparison traits.

Adds a platform-specific function, `split_paths` to the `os` module. This
function can be used to parse PATH-like environment variables according to
local platform conventions.

Closes #14352.

This commit adds the groundwork for the renaming of the Total{Eq,Ord} traits.
After this commit hits a snapshot, the traits can be renamed.

The last example in the containers and iterators guide had a superfluous owned vector in it. Everything works fine without it, so I removed it to avoid confusion.

This is part of the ongoing renaming of the equality traits. See #12517 for more
details. All code using Eq/Ord will temporarily need to move to Partial{Eq,Ord}
or the Total{Eq,Ord} traits. The Total traits will soon be renamed to {Eq,Ord}.

cc #12517

[breaking-change]

CC @alexcrichton
Closes #14545