As per issue #136827 submitting updates to E0495 documentation

[progressive-galib]

documentation updated

[rustbot]

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

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[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 2.775 Building wheels for collected packages: reuse
#12 2.776   Building wheel for reuse (pyproject.toml): started
#12 2.984   Building wheel for reuse (pyproject.toml): finished with status 'done'
#12 2.985   Created wheel for reuse: filename=reuse-4.0.3-cp310-cp310-manylinux_2_35_x86_64.whl size=132719 sha256=be6760d5849de4a58bbe52b85ca57a55f2b32b518b17029a5ad2e530db0d4303
#12 2.986   Stored in directory: /tmp/pip-ephem-wheel-cache-z2llq0xa/wheels/3d/8d/0a/e0fc6aba4494b28a967ab5eaf951c121d9c677958714e34532
#12 2.988 Installing collected packages: boolean-py, binaryornot, tomlkit, reuse, python-debian, markupsafe, license-expression, jinja2, chardet, attrs
#12 3.379 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 3.379 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 3.906 Collecting virtualenv
#12 3.906 Collecting virtualenv
#12 3.942   Downloading virtualenv-20.29.2-py3-none-any.whl (4.3 MB)
#12 4.006      ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 4.3/4.3 MB 68.8 MB/s eta 0:00:00
#12 4.060 Collecting platformdirs<5,>=3.9.1
#12 4.063   Downloading platformdirs-4.3.6-py3-none-any.whl (18 kB)
#12 4.098 Collecting filelock<4,>=3.12.2
#12 4.118 Collecting distlib<1,>=0.3.7
#12 4.121   Downloading distlib-0.3.9-py2.py3-none-any.whl (468 kB)
#12 4.128      ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 469.0/469.0 KB 96.0 MB/s eta 0:00:00
#12 4.128      ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 469.0/469.0 KB 96.0 MB/s eta 0:00:00
#12 4.208 Installing collected packages: distlib, platformdirs, filelock, virtualenv
#12 4.389 Successfully installed distlib-0.3.9 filelock-3.17.0 platformdirs-4.3.6 virtualenv-20.29.2
#12 DONE 4.5s

#13 [7/8] COPY host-x86_64/mingw-check/validate-toolstate.sh /scripts/
#13 DONE 0.0s
---
DirectMap4k:      124864 kB
DirectMap2M:     7215104 kB
DirectMap1G:    11534336 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
    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`.
downloading https://static.rust-lang.org/dist/2025-02-08/rustfmt-nightly-x86_64-unknown-linux-gnu.tar.xz
---
fmt check
fmt: checked 5843 files
tidy check
tidy: Skipping binary file check, read-only filesystem
##[error]tidy error: /checkout/compiler/rustc_error_codes/src/error_codes/E0495.md:1: line longer than 80 chars
##[error]tidy error: /checkout/compiler/rustc_error_codes/src/error_codes/E0495.md:19: line longer than 80 chars
removing old virtual environment
creating virtual environment at '/checkout/obj/build/venv' using 'python3.10' and 'venv'
creating virtual environment at '/checkout/obj/build/venv' using 'python3.10' and 'virtualenv'
Requirement already satisfied: pip in ./build/venv/lib/python3.10/site-packages (25.0.1)
All checks passed!
checking python file formatting
28 files already formatted
checking C++ file formatting
checking C++ file formatting
some tidy checks failed
Command has failed. Rerun with -v to see more details.
  local time: Fri Feb 14 20:43:02 UTC 2025
  network time: Fri, 14 Feb 2025 20:43:03 GMT
##[error]Process completed with exit code 1.
Post job cleanup.

[Noratrieb]

I don't think this is what this error stands for, I think this is a much more generic lifetime error from searching for the code in ./tests.

I would probably just keep the old documentation, it's not amazing but I don't think it's possible to write documentation with great examples for this error code, it just seems like this is a very generic error code emitted in all sorts of cases.

@compiler-errors maybe you know more about this error code and whether what I said is correct. (emitted here

rust/compiler/rustc_trait_selection/src/error_reporting/infer/region.rs

Line 994 in c3fe9e7

fn report_inference_failure(&self, var_origin: RegionVariableOrigin) -> Diag<'_> {

)

[Noratrieb]

@progressive-galib thank you for the PR, I've left some feedback on the contents. As this is your first PR, some tips on how to best write a PR title and description: This fixes an issue, and if you leave fixes #136827 in the PR description, GitHub will automatically close the issue when this PR is merged (you can check the docs for more information). It will also mean that it's easy to go to the issue from the PR because it has a nicely clickable link.
For the PR title, I would recommend structuring it as just describing what you did, not relating to the issue. I might have called it "Update E0495 documentation to say that error is emitted" or something like that. The "As per issue #137042 submitting" is not needed, as the PR description will mention the issue already and it's clear that you're submitting this :).
While in this case that's not really necessary, it's generally also useful to include some text in the PR description about why you're doing this change, so that it's easier for the reviewer or a later visitor to understand what's going on here.

Don't worry about getting it wrong here, it's fine, you can update it here and for next time :).

[apiraino]

@progressive-galib can you have a look at the latest feedback when you have a moment?

Switching to waiting on author to incorporate changes. Feel free to request a review with @rustbot ready, thanks!

@rustbot author