doc-comments on unstable features should end up in the unstable book

[jyn514]

Location

https://doc.rust-lang.org/nightly/unstable-book/language-features/abi-unadjusted.html

Summary

abi_unadjusted is a perma-unstable language feature. it has docs inline in unstable.rs:

rust/compiler/rustc_feature/src/unstable.rs

Lines 190 to 191 in d3a2440

	/// Allows using the `unadjusted` ABI; perma-unstable.
	(internal, abi_unadjusted, "1.16.0", None),

those docs should end up in the unstable-book, so it's not purely a stub. hopefully this will make it easier for people to document perma-unstable features so we have fewer features with no docs at all.

[jyn514]

mentoring instructions: change

rust/src/tools/tidy/src/features.rs

Line 286 in d3a2440

fn collect_lang_features_in(features: &mut Features, base: &Path, file: &str, bad: &mut bool) {

to also collect doc-comments. then change these two functions to include those docs:

rust/src/tools/unstable-book-gen/src/main.rs

Lines 15 to 23 in d3a2440

	fn generate_stub_issue(path: &Path, name: &str, issue: u32) {
	let content = format!(include_str!("stub-issue.md"), name = name, issue = issue);
	t!(write(path, content), path);
	}
	fn generate_stub_no_issue(path: &Path, name: &str) {
	let content = format!(include_str!("stub-no-issue.md"), name = name);
	t!(write(path, content), path);
	}

@rustbot label +E-Easy +E-mentor +E-help-wanted

[ranger-ross]

Hey, I'd like to pick this up :)

@rustbot claim

[Todun01]

i'd like to pick this up please! @rustbot claim