Add comment when new directory is added to `tests/ui`

[reddevilmidzy]

If a new directory is added under tests/ui, it would be nice to add a comment to tests/ui/README.md to update it as well.

There are a few directories that are not described in README.md.

[Urgau]

We don't currently have a [mentions] type that would be sutible for this this usecase.

We would need a way to detect when there is a change (add or remove) to a top-level sub-directory, I don't know if git records such information.

Would you happen to have an example PR where it would have been useful?

[reddevilmidzy]

For example, the tests/ui/ffi directory was created in #146490.
But tests/ui/README.md was not updated. (see tests/ui/README.md)
So I updated in this PR #149767

I know that it's not often that a tests/ui/ subdirectory is created. However, I opened an issue because I thought it would be cumbersome for reviewers to check that a directory was added.

Wouldn't it be better to create a file that collects the currently existing directories, like issues.txt, and check it?

[Urgau]

Thanks for the example.

Unfortunately, as I suspected, GitHub/git does not give us any information on the individual directories, see the return of the API where only the individual files are listed. We have no way of knowing that tests/ui/ffi directory is new with the current method we use.

Wouldn't it be better to create a file that collects the currently existing directories, like issues.txt, and check it?

Sure that would work, and wouldn't require any changes to triagebot it-self.

Similar to issues.txt, tidy could be thought to keep a file ui-suites.txt in-sync, and any changes to that file could be monitored by a [mentions] in rust-lang/rust.

Does this makes sense to you? Would you like to work on that?

[reddevilmidzy]

sure, thanks I appreciate it:)

[Urgau]

Then let's move this discussion to rust-lang/rust.

[Urgau]

There are two things that needs to be done:

1. Update tidy so it keeps a file (let's name it ui-suites.txt) in sync with the top-level directories of tests/ui. Feel free to take inspiration from the current issues.txt handling.

   rust/src/tools/tidy/src/ui_tests.rs

   Lines 48 to 75 in 8da80d3

   	let remaining_issue_names = recursively_check_ui_tests(&mut check, path, &allowed_issue_names);
   	// if there are any file names remaining, they were moved on the fs.
   	// our data must remain up to date, so it must be removed from issues.txt
   	// do this automatically on bless, otherwise issue a tidy error
   	if bless && (!remaining_issue_names.is_empty() || !is_sorted) {
   	let tidy_src = root_path.join("src/tools/tidy/src");
   	// instead of overwriting the file, recreate it and use an "atomic rename"
   	// so we don't bork things on panic or a contributor using Ctrl+C
   	let blessed_issues_path = tidy_src.join("issues_blessed.txt");
   	let mut blessed_issues_txt = fs::File::create(&blessed_issues_path).unwrap();
   	blessed_issues_txt.write_all(ISSUES_TXT_HEADER.as_bytes()).unwrap();
   	// If we changed paths to use the OS separator, reassert Unix chauvinism for blessing.
   	for filename in allowed_issue_names.difference(&remaining_issue_names) {
   	writeln!(blessed_issues_txt, "{filename}").unwrap();
   	}
   	let old_issues_path = tidy_src.join("issues.txt");
   	fs::rename(blessed_issues_path, old_issues_path).unwrap();
   	} else {
   	for file_name in remaining_issue_names {
   	let mut p = PathBuf::from(path);
   	p.push(file_name);
   	check.error(format!(
   	"file `{}` no longer exists and should be removed from the exclusions in `src/tools/tidy/src/issues.txt`",
   	p.display()
   	));
   	}
   	}

2. Update this repo triagebot.toml with a new [mentions], take inspiration from the existing mentions.

   rust/triagebot.toml

   Lines 1117 to 1121 in 8da80d3

   	[mentions."src/tools/compiletest/src/directives"]
   	message = """
   	`compiletest` directives have been modified. Please add or update docs for the
   	new or modified directive in `src/doc/rustc-dev-guide/`.
   	"""