after rust-lang#95612, only linux and windows target are build with -Zunstable-options, 
but others platforms might use -Csplit-debuginfo

add "openbsd" target in the list of platforms using it.

…appropriate

When we don't find an item we search all of them for an appropriate
import and suggest `use`ing it. This is sometimes done for expressions
that have paths with more than one segment. We now also suggest changing
that path to work with the `use`.

Fix rust-lang#95413

`ProjectionElem:::Downcast` is used when downcasting to a variant of
an enum or a generator, regardless of the number of variants.

…rors

When suggesting to import an item, also suggest changing the path if appropriate

When we don't find an item we search all of them for an appropriate
import and suggest `use`ing it. This is sometimes done for expressions
that have paths with more than one segment. We now also suggest changing
that path to work with the `use`.

Fix rust-lang#95413

rustdoc: Resolve doc links on fields during early resolution

Another subset of rust-lang#94857 which fixes rust-lang#96429.

This case regressed in rust-lang#96135 when `may_have_doc_links`-based filtering was introduced.
Before that filtering structs could collect traits in scope for their fields, but after the filtering structs won't collect anything if they don't have doc comments on them, so we have to visit fields too.

…idtwco,Mark-Simulacrum

openbsd: unbreak build on native platform

after rust-lang#95612, only linux and windows target are build with `-Zunstable-options`, but others platforms might use `-Csplit-debuginfo`

currently, without this PR, the build of rustc on OpenBSD fails with:

```
Building stage0 tool unstable-book-gen (x86_64-unknown-openbsd)
running: "/data/semarie/build-rust/install_dir/beta/bin/cargo" "build" "--target" "x86_64-unknown-openbsd" "-Zbinary-dep-depinfo" "-j" "4" "-v" "--release" "--frozen" "--manifest-path"
"/data/semarie/build-rust/build_dir/rustc-nightly-src/src/tools/unstable-book-gen/Cargo.toml" "--message-format" "json-render-diagnostics"
error: failed to run `rustc` to learn about target-specific information

Caused by:
  process didn't exit successfully: `/data/semarie/build-rust/build_dir/build/bootstrap/debug/rustc - --crate-name ___ --print=file-names --cfg=bootstrap -Csymbol-mangling-version=v0 -Zmacro-backtrace -Clink-args=-Wl,-z,origin
'-Clink-args=-Wl,-rpath,$ORIGIN/../lib' -Csplit-debuginfo=off -Ztls-model=initial-exec --target x86_64-unknown-openbsd --crate-type bin --crate-type rlib --crate-type dylib --crate-type cdylib --crate-type staticlib --crate-type proc-macro
--print=sysroot --print=cfg` (exit status: 1)
  --- stdout

  Did not run successfully: exit status: 1
  "/data/semarie/build-rust/install_dir/beta/bin/rustc" "-" "--crate-name" "___" "--print=file-names" "--cfg=bootstrap" "-Csymbol-mangling-version=v0" "-Zmacro-backtrace" "-Clink-args=-Wl,-z,origin" "-Clink-args=-Wl,-rpath,$ORIGIN/../lib"
"-Csplit-debuginfo=off" "-Ztls-model=initial-exec" "--target" "x86_64-unknown-openbsd" "--crate-type" "bin" "--crate-type" "rlib" "--crate-type" "dylib" "--crate-type" "cdylib" "--crate-type" "staticlib" "--crate-type" "proc-macro"
"--print=sysroot" "--print=cfg" "-Wrust_2018_idioms" "-Wunused_lifetimes" "-Wsemicolon_in_expressions_from_macros" "-Dwarnings" "--sysroot" "/data/semarie/build-rust/install_dir/beta"
  -------------

  --- stderr
  error: `-Csplit-debuginfo` is unstable on this platform

command did not execute successfully: "/data/semarie/build-rust/install_dir/beta/bin/cargo.bin" "build" "--target" "x86_64-unknown-openbsd" "-Zbinary-dep-depinfo" "-j" "4" "-v" "--release" "--frozen" "--manifest-path"
```

I am suspecting that all unix might be affected, but I am unsure about the right conditional to use. so I only added "openbsd" target inside it as I am able to test it.

rustc nightly built correctly with this PR on openbsd.

Include nonexported macro_rules! macros in the doctest target

Fixes rust-lang#88038

This PR aims to include nonexported `macro_rules!` macros in the doctest target. For more details, please see the above issue.

Fix typo in lint levels doc

…-test, r=petrochenkov

Fix flaky rustdoc-ui test because it did not replace time result

As mentioned in rust-lang#93715: a test is flaky because I forgot to replace the time value.

This PR fixes it.

r? `@petrochenkov`

…kh726

Quick fix for rust-lang#96223.

This PR is a quick fix regarding rust-lang#96223.

As mentioned in the issue, others modification could be added to not elide types with bound vars from suggestions.

Special thanks to `@jackh726` for mentoring and `@Manishearth` for minimal test case.

r? `@jackh726`

Update `ProjectionElem::Downcast` documentation

`ProjectionElem:::Downcast` is used when downcasting to a variant of
an enum or a generator, regardless of the number of variants.