Remove `Word` from the `unix_sigpipe` attribute template so that plain
`#[unix_sigpipe]` is not included in suggestions of valid forms of the
attribute. Also re-arrange diagnostics code slightly to avoid duplicate
diagnostics.
unix_sigpipe: Simple fixes and improvements in tests
In https://github.com/rust-lang/rust/pull/120832 I included 5 preparatory commits.
It will take a while before discussions there and in https://github.com/rust-lang/rust/issues/62569 is settled, so here is a PR that splits out 4 of the commits that are easy to review, to get them out of the way.
r? ``@davidtwco`` who already approved these commits in https://github.com/rust-lang/rust/pull/120832 (but I have tweaked them a bit and rebased them since then).
For the convenience of my reviewer, here are the full commit messages of the commits:
<details>
<summary>Click to expand</summary>
```
commit 948b1d68ab (HEAD -> unix_sigpipe-tests-fixes, origin/unix_sigpipe-tests-fixes)
Author: Martin Nordholts <martin.nordholts@codetale.se>
Date: Fri Feb 9 07:57:27 2024 +0100
tests: Add unix_sigpipe-different-duplicates.rs test variant
To make sure that
#[unix_sigpipe = "x"]
#[unix_sigpipe = "y"]
behaves like
#[unix_sigpipe = "x"]
#[unix_sigpipe = "x"]
commit d14f15862d
Author: Martin Nordholts <martin.nordholts@codetale.se>
Date: Fri Feb 9 08:47:47 2024 +0100
tests: Combine unix_sigpipe-not-used.rs and unix_sigpipe-only-feature.rs
The only difference between the files is the presence/absence of
#![feature(unix_sigpipe)]
attribute. Avoid duplication by using revisions instead.
commit a1cb3dba84
Author: Martin Nordholts <martin.nordholts@codetale.se>
Date: Fri Feb 9 06:44:56 2024 +0100
tests: Rename unix_sigpipe.rs to unix_sigpipe-bare.rs for clarity
The test is for the "bare" variant of the attribute that looks like this:
#[unix_sigpipe]
which is not allowed, because it must look like this:
#[unix_sigpipe = "sig_ign"]
commit e060274e55
Author: Martin Nordholts <martin.nordholts@codetale.se>
Date: Fri Feb 9 05:48:24 2024 +0100
tests: Fix typo unix_sigpipe-error.rs -> unix_sigpipe-sig_ign.rs
There is no error expected. It's simply the "regular" test for sig_ign.
So rename it.
```
</details>
Tracking issue: https://github.com/rust-lang/rust/issues/97889
In `auxiliary/sigpipe-utils.rs`, all we want to know is the current
`SIGPIPE` disposition. We should not change it. So use `libc::sigaction`
instead of `libc::signal`. That way we can also remove the code that
restores it.
The test is for the "bare" variant of the attribute that looks like this:
#[unix_sigpipe]
which is not allowed, because it must look like this:
#[unix_sigpipe = "sig_ign"]
