Document From::from impls

[TimTheBig]

This resolves #51430 by documenting all from impls in lib std and core.
I still need someone to look over a few of the comments to see if the style is correct.

[rustbot]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @Amanieu (or someone else) some time within the next two weeks.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

• @rustbot author: the review is finished, PR author should check the comments and take action accordingly
• @rustbot review: the author is ready for a review, this PR will be queued again in the reviewer's queue

[rustbot]

The Miri subtree was changed

cc @rust-lang/miri

Portable SIMD is developed in its own repository. If possible, consider making this change to rust-lang/portable-simd instead.

cc @calebzulawski, @programmerjake

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

[TimTheBig]

@rustbot label A-docs C-enhancement T-libs-api

[TimTheBig]

Should I move Portable SIMD and rust-analyzer changes even though they are small?

[RalfJung]

It is generally a good idea to split up large changes. :) You changed a whole bunch of files in rust-analyzer, so yeah that should be split. Miri and clippy have fewer changes, but the fact that there are any changes at all there still contradicts the PR description.

It's too late now, but the best strategy for PRs like this is to start with just a few files, e.g. just core, take the review feedback, and then apply that to the next PRs. That avoids having to re-do large amounts of work when there is overarching feedback.

[rustbot]

The Miri subtree was changed

cc @rust-lang/miri

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

Portable SIMD is developed in its own repository. If possible, consider making this change to rust-lang/portable-simd instead.

cc @calebzulawski, @programmerjake

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

[TimTheBig]

My mistake, I will revert the rust-analyzer changes.

[oli-obk]

This PR requires a lot of changes, I did not get far with reviews, but a lot of the doc comments only explain the body in its rawest form. I feel like fully reviewing this just makes the reviewer do the work of documenting things, so it may be easier to just write PRs with documentation.

Also please disclose whether you generated this documentation, even just partially or as an initial thing that you edited.

[TimTheBig]

I'm still seeing changes in src/tools in this PR.

This has been resolved.

[rustbot]

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

[rust-log-analyzer]

The job mingw-check-tidy failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

info: removing rustup binaries
info: rustup is uninstalled
##[group]Image checksum input
mingw-check-tidy
# We use the ghcr base image because ghcr doesn't have a rate limit
# and the mingw-check-tidy job doesn't cache docker images in CI.
FROM ghcr.io/rust-lang/ubuntu:22.04

ARG DEBIAN_FRONTEND=noninteractive
RUN apt-get update && apt-get install -y --no-install-recommends \
  g++ \
  make \
---

COPY host-x86_64/mingw-check/validate-toolstate.sh /scripts/
COPY host-x86_64/mingw-check/validate-error-codes.sh /scripts/

# NOTE: intentionally uses python2 for x.py so we can test it still works.
# validate-toolstate only runs in our CI, so it's ok for it to only support python3.
ENV SCRIPT TIDY_PRINT_DIFF=1 python2.7 ../x.py test \
           --stage 0 src/tools/tidy tidyselftest --extra-checks=py,cpp
#
# This file is autogenerated by pip-compile with Python 3.10
# by the following command:
#
#    pip-compile --allow-unsafe --generate-hashes reuse-requirements.in
---
#12 2.823 Building wheels for collected packages: reuse
#12 2.824   Building wheel for reuse (pyproject.toml): started
#12 3.036   Building wheel for reuse (pyproject.toml): finished with status 'done'
#12 3.036   Created wheel for reuse: filename=reuse-4.0.3-cp310-cp310-manylinux_2_35_x86_64.whl size=132720 sha256=0c2fd2aaf7b0bf8d6e131220aff14712a774c2ca462f3204d25460cbcf610b63
#12 3.037   Stored in directory: /tmp/pip-ephem-wheel-cache-1g1ihj07/wheels/3d/8d/0a/e0fc6aba4494b28a967ab5eaf951c121d9c677958714e34532
#12 3.039 Successfully built reuse
#12 3.039 Installing collected packages: boolean-py, binaryornot, tomlkit, reuse, python-debian, markupsafe, license-expression, jinja2, chardet, attrs
#12 3.456 Successfully installed attrs-23.2.0 binaryornot-0.4.4 boolean-py-4.0 chardet-5.2.0 jinja2-3.1.4 license-expression-30.3.0 markupsafe-2.1.5 python-debian-0.1.49 reuse-4.0.3 tomlkit-0.13.0
#12 3.456 WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv
#12 3.992 Collecting virtualenv
#12 4.116   Downloading virtualenv-20.29.3-py3-none-any.whl (4.3 MB)
#12 4.335      ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 4.3/4.3 MB 20.1 MB/s eta 0:00:00
#12 4.378 Collecting distlib<1,>=0.3.7
#12 4.411   Downloading distlib-0.3.9-py2.py3-none-any.whl (468 kB)
#12 4.419      ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 469.0/469.0 KB 78.8 MB/s eta 0:00:00
#12 4.459 Collecting filelock<4,>=3.12.2
#12 4.491   Downloading filelock-3.18.0-py3-none-any.whl (16 kB)
#12 4.526 Collecting platformdirs<5,>=3.9.1
#12 4.559   Downloading platformdirs-4.3.7-py3-none-any.whl (18 kB)
#12 4.641 Installing collected packages: distlib, platformdirs, filelock, virtualenv
#12 4.827 Successfully installed distlib-0.3.9 filelock-3.18.0 platformdirs-4.3.7 virtualenv-20.29.3
#12 4.828 WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv
#12 DONE 4.9s

#13 [7/8] COPY host-x86_64/mingw-check/validate-toolstate.sh /scripts/
#13 DONE 0.0s
---
DirectMap4k:      120768 kB
DirectMap2M:     8267776 kB
DirectMap1G:    10485760 kB
##[endgroup]
Executing TIDY_PRINT_DIFF=1 python2.7 ../x.py test            --stage 0 src/tools/tidy tidyselftest --extra-checks=py,cpp
+ TIDY_PRINT_DIFF=1 python2.7 ../x.py test --stage 0 src/tools/tidy tidyselftest --extra-checks=py,cpp
##[group]Building bootstrap
    Finished `dev` profile [unoptimized] target(s) in 0.05s
##[endgroup]
WARN: currently no CI rustc builds have rustc debug assertions enabled. Please either set `rust.debug-assertions` to `false` if you want to use download CI rustc or set `rust.download-rustc` to `false`.
[TIMING] core::build_steps::tool::LibcxxVersionTool { target: x86_64-unknown-linux-gnu } -- 0.217
---
##[endgroup]
[TIMING] core::build_steps::tool::ToolBuild { compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu, tool: "tidy", path: "src/tools/tidy", mode: ToolBootstrap, source_type: InTree, extra_features: [], allow_features: "", cargo_args: [], artifact_kind: Binary } -- 36.822
[TIMING] core::build_steps::tool::Tidy { compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu } -- 0.000
fmt check
Diff in /checkout/library/alloc/src/bstr.rs:673:
 #[cfg(all(not(no_rc), not(no_sync), target_has_atomic = "ptr"))]
 impl From<Arc<ByteStr>> for Arc<[u8]> {
     /// Create a `Arc<[u8]>` from the inner bytes of `Arc<ByteStr>`.
-    
+
     #[inline]
     fn from(s: Arc<ByteStr>) -> Arc<[u8]> {
         // SAFETY: `ByteStr` is a transparent wrapper around `[u8]`.
fmt: checked 5926 files
Build completed unsuccessfully in 0:01:19
  local time: Tue Mar 25 00:53:37 UTC 2025
  network time: Tue, 25 Mar 2025 00:53:37 GMT
##[error]Process completed with exit code 1.