…n time

VxWorks does not provide a way to set the task name except at creation time

… document.

Feature gate definitions were split into multiple files in rust-lang#63824 but
tidy kept reporting the hard-coded path. Now, it shows the full path
to the correct file.

This is just in preparation for future usage of these texts.

…_or`.

…lace.

This replaces the ad-hoc tuples used in the different feature gate files
and unifies their content into a common type, leading to more readable
matches and other good stuff that comes from having named fields. It
also contains the description of each feature as extracted from the doc
comment.

Tries to clarify the filtering of active features and make the code more
expressive.

Do not complain about unused code when used in `impl` `Self` type

Fix rust-lang#18290.

…ebank

Fully implement or-pattern parsing

Builds upon the initial parsing in rust-lang#61708 to fully implement or-pattern (`p | q`) parsing as specified in [the grammar section of RFC 2535](https://github.com/rust-lang/rfcs/blob/master/text/2535-or-patterns.md#grammar).

Noteworthy:

- We allow or-patterns in `[p | q, ...]`.
- We allow or-patterns in `let` statements and `for` expressions including with leading `|`.
- We improve recovery for `p || q` (+ tests for that in `multiple-pattern-typo.rs`).
- We improve recovery for `| p | q` in inner patterns (tests in `or-patterns-syntactic-fail.rs`).
- We rigorously test or-pattern parsing (in `or-patterns-syntactic-{pass,fail}.rs`).
- We harden the feature gating tests.
- We do **_not_** change `ast.rs`. That is, `ExprKind::Let.0` and `Arm.pats` still accept `Vec<P<Pat>>`.
   I was starting work on that but it would be cleaner to do this in a separate PR so this one has a narrower scope.

cc @dlrobertson
cc the tracking issue rust-lang#54883.

r? @estebank

VxWorks does not provide a way to set the task name except at creation time

Make set_name do thing as VxWorks does not provide a way to set the task name except at creation time.

r? @alexcrichton

cc @n-salim

…nikomatsakis

Removed a confusing FnOnce example

# Description
See rust-lang#47091 for a discussion.

## Changes
- Removed an example that might suggest readers that square_x is (only) FnOnce.

closes rust-lang#47091

…=Centril

Refactor feature gates

After rust-lang#63824, this goes a few steps further by

- parsing doc comments in the macros to extract descriptions for feature gates, and
- introducing a common `Feature` type to replace the tuples used previously to improve readability.

The descriptions are not yet used, but I felt like this PR is a useful enough refactoring on its own.

r? @Centril

add link to FileCheck docs

Thanks @gnzlbg for pointing me to those docs.