compiler-docs: Missing trait impls for type

[tesuji]

This is a regression from stable to beta, although this issue will be P-low.
The problem is #73771 ignored documenting unstable traits for non-local types,
#76571 fixes some regressions caused by it but the regression
in nightly-rustc / compiler docs still opens.

For example: Compare https://doc.rust-lang.org/nightly/nightly-rustc/rustc_expand/base/struct.ExtCtxt.html#blanket-implementations and https://doc.rust-lang.org/1.46.0/nightly-rustc/rustc_expand/base/struct.ExtCtxt.html#blanket-implementations .

The doc in 1.46.0 has MaybeResult impl, while on nightly it doesn't have.

A way to fix this issue is ignoring this check when the compiling-crates
are being passed -Zforce-unstable-if-unmarked flag or the crate/module has rustc_private feature:

rust/src/librustdoc/clean/inline.rs

Lines 345 to 374 in c743fc4

	if let Some(stab) = tcx.lookup_stability(did) {
	if stab.level.is_unstable() && stab.feature == sym::rustc_private {
	return;
	}
	}
	}
	}
	let for_ = if let Some(did) = did.as_local() {
	let hir_id = tcx.hir().local_def_id_to_hir_id(did);
	match tcx.hir().expect_item(hir_id).kind {
	hir::ItemKind::Impl { self_ty, .. } => self_ty.clean(cx),
	_ => panic!("did given to build_impl was not an impl"),
	}
	} else {
	tcx.type_of(did).clean(cx)
	};
	// Only inline impl if the implementing type is
	// reachable in rustdoc generated documentation
	if !did.is_local() {
	if let Some(did) = for_.def_id() {
	if !cx.renderinfo.borrow().access_levels.is_public(did) {
	return;
	}
	if let Some(stab) = tcx.lookup_stability(did) {
	if stab.level.is_unstable() && stab.feature == sym::rustc_private {
	return;
	}

Meta

rustc --version --verbose: Version 1.48.0-nightly (9b41541 2020-09-14)

[jakevossen5]

Hey! I would like to check this out if that is okay

[camelid]

Is this actually a regression?

[Mark-Simulacrum]

Dropping regression label. nightly-rustc docs are, well, not really important on non-nightly channels, as they cannot be used by normal consumers.

[jyn514]

@jakevossen5 if you're still interested in working on this we'd love to have the help!
If you have trouble, feel free to ask for help in the rustdoc channel or on Zulip :)

[jakevossen5]

@jyn514 Thanks! Yes, I am still interested, I have been busy that past few weeks. I will give it a shot this weekend and will reach out if I can't figure it out!

[tesuji]

@jakevossen5 Since zulip is lag in my region at night, I post a respond here.
You could use tcx.sess.opts.debugging_opts.force_unstable_if_unmarked to check for
-Zforce-unstable-if-unmarked flag passed during compilation.

[leokhachatorians]

I think I'll hop onto this if that's OK. I've always wanted to contribute :)

[jakevossen5]

Go for it!

[ShoyuVanilla]

It doesn't seem to be fixed by #121218 😢 I'll check the cause