Co-authored-by: Josh Triplett <josh@joshtriplett.org>

Fixes rust-lang#74134

After PR rust-lang#72771 this would trigger an intra_doc_link_resolution_failure warning
when rustdoc is invoked without --document-private-items. Links from private
items to private types are however never actually generated in that case and
thus shouldn't produce a warning. These links are in fact a very useful tool to
document crate internals.

Tests are added for all 4 combinations of public/private items and link
targets. Test 1 is the case mentioned above and fails without this commit. Tests
2 - 4 passed before already but are added nonetheless to prevent regressions.

As per the discussion in PR rust-lang#74147, the 4 individual tests are replaced by a
single one.

The test is expanded to cover all 4 public/private cases, each with and without
--document-private-items.

…Simulacrum

Update RELEASES.md for 1.45.0

### [Rendered](https://github.com/XAMPPRocky/rust/blob/relnotes-1.45.0/RELEASES.md)

r? @Mark-Simulacrum
cc @rust-lang/release

…llaumeGomez

rustdoc: insert newlines between attributes

Fixes rust-lang#73205.

…riplett

Document the union keyword

Partial fix of rust-lang#34601.

This documents the `union` keyword by presenting three cases: simply using a union, matching on a union and referencing the fields of a union.

@rustbot modify labels: T-doc,C-enhancement

…-Simulacrum

Fix caching issue when building tools.

This fixes a problem with tool builds not being cached properly.

rust-lang#73297 changed it so that Clippy will participate in the "deny warnings" setting. Unfortunately this causes a problem because Clippy shares the build directory with other tools which do not participate in "deny warnings".  Because Cargo does not independently cache artifacts based on different RUSTFLAGS settings, it causes all the shared dependencies to get rebuilt if Clippy ever gets built.

The solution here is to stop using RUSTFLAGS, and just sneak the settings in through the rustc wrapper. Cargo won't know about the different settings, so it will not bust the cache. This should be safe since lint settings on dependencies are ignored. This is how things used to work in the past before rust-lang#64316.

Alternate solutions:
* Treat Clippy as a "submodule" and don't enforce warnings on it. This was the behavior before rust-lang#73297. The consequence is that if a warning sneaks into clippy, that the clippy maintainers will need to fix it when they sync clippy back to the clippy repo.
* Just deny warnings on all tools (removing the in-tree/submodule distinction). This is tempting, but with some issues (cc rust-lang#52336):
  * Adding or changing warnings in rustc can be difficult to land because tools have to be updated if they trip the warning. In practice, this isn't too bad.  Cargo (and rustfmt) already runs with `deny(warnings)`, so this has been the de-facto standard already (although they do not use the extra lints like `unused_lifetimes`).
* Teach Cargo to add flags to the workspace members, but not dependencies.
* Teach Cargo to add flags without fingerprinting them?
* Teach Cargo to independently cache different RUSTFLAGS artifacts (this was [reverted](rust-lang/cargo#7417) due to complications). This would also unnecessarily rebuild dependencies, but would avoid cache thrashing.
* Teach Cargo about lint settings.

Closes rust-lang#74016

…kfire

clean up E0718 explanation

r? @Dylan-DPC

…jyn514

rustdoc: Allow linking from private items to private types

Fixes rust-lang#74134

After PR rust-lang#72771 this would trigger an intra_doc_link_resolution_failure warning
when rustdoc is invoked without --document-private-items. Links from private
items to private types are however never actually generated in that case and
thus shouldn't produce a warning. These links are in fact a very useful tool to
document crate internals.

Tests are added for all 4 combinations of public/private items and link
targets. Test 1 is the case mentioned above and fails without this commit. Tests
2 - 4 passed before already but are added nonetheless to prevent regressions.

rust-lang#71669: add ui, codegen tests for volatile + nearby int intrinsics

Added some tests for intrinsics. See rust-lang#71669.

…Gomez

Added detailed error code explanation for issue E0688 in Rust compiler.

Added proper error explanation for issue E0688 in the Rust compiler.
Error Code E0688

Sub Part of Issue rust-lang#61137

r? @GuillaumeGomez