Auto merge of #59550 - Centril:rollup, r=Centril

Rollup of 10 pull requests

Successful merges:

 - #59376 (RFC 2008: Enum Variants)
 - #59453 (Recover from parse error in tuple syntax)
 - #59455 (Account for short-hand field syntax when suggesting borrow)
 - #59499 (Fix broken download link in the armhf-gnu image)
 - #59512 (implement `AsRawFd` for stdio locks)
 - #59525 (Whitelist some rustc attrs)
 - #59528 (Improve the dbg! macro docs )
 - #59532 (In doc examples, don't ignore read/write results)
 - #59534 (rustdoc: collapse blanket impls in the same way as normal impls)
 - #59537 (Fix OnceWith docstring.)

Failed merges:

r? @ghost

Author: bors

src/ci/docker/armhf-gnu/Dockerfile

@@ -71,7 +71,8 @@ COPY scripts/qemu-bare-bones-addentropy.c /tmp/addentropy.c
 RUN arm-linux-gnueabihf-gcc addentropy.c -o rootfs/addentropy -static
 
 # TODO: What is this?!
-RUN curl -O http://ftp.nl.debian.org/debian/dists/jessie/main/installer-armhf/current/images/device-tree/vexpress-v2p-ca15-tc1.dtb
+# Source of the file: https://github.com/vfdev-5/qemu-rpi2-vexpress/raw/master/vexpress-v2p-ca15-tc1.dtb
+RUN curl -O https://s3-us-west-1.amazonaws.com/rust-lang-ci2/rust-ci-mirror/vexpress-v2p-ca15-tc1.dtb
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh

src/doc/unstable-book/src/language-features/non-exhaustive.md

@@ -7,10 +7,12 @@ The tracking issue for this feature is: [#44109]
 ------------------------
 
 The `non_exhaustive` gate allows you to use the `#[non_exhaustive]` attribute
-on structs and enums. When applied within a crate, users of the crate will need
-to use the `_` pattern when matching enums and use the `..` pattern when
-matching structs. Structs marked as `non_exhaustive` will not be able to be
-created normally outside of the defining crate. This is demonstrated below:
+on structs, enums and enum variants. When applied within a crate, users of the
+crate will need to use the `_` pattern when matching enums and use the `..`
+pattern when matching structs. Enum variants cannot be matched against.
+Structs and enum variants marked as `non_exhaustive` will not be able to
+be created normally outside of the defining crate. This is demonstrated
+below:
 
 ```rust,ignore (pseudo-Rust)
 use std::error::Error as StdError;
@@ -72,4 +74,3 @@ let config = Config { window_width: 640, window_height: 480 };
 // when marked non_exhaustive.
 let &Config { window_width, window_height, .. } = config;
 ```
-