What do you think is for, other than declaring something “private” that the language unfortunately doesn’t let you declare as truly private right now?
I’ve mostly seen it used as a way to expose tools to macro APIs. For example, these internal parts of the quote!
macro, or these internal parts of the vec!
macro. Changing these things shouldn’t be considered a semver violation, because they’re not really part of the API, even though the quote!
macro can’t enforce it.
The only other cases I can think of where I’ve seen used are even bigger kludges, and the hidden items definitely aren’t part of the platonic API, like pre-
crates that wanted to reserve the right to add new variants to their enums.
I’m arguing (humbly of course) that intended vs. unintended use of what is at the end of the day a part of the public interface shouldn’t be taken into consideration by default. Otherwise, other cases can be argued as non-breaking too!
Foo
was never meant to be sent to other threads, So, losing Send
is not a semver- breaking change!
Exhaustive enum Bar
is only meant to be matched exhaustively internally. We say so in the docs. So adding a variant to it is not a semver-breaking change!
And giving more powers to a (kludge) doc attribute just doesn’t seem in my eyes to be a generally wise move.
A: cargo-semver
is still complaining about this item which I already have cfg-ed under an exp_api
crate feature (which I don’t want to rename). CI is failing.
B: PRO-TIP: Just slap a on it and CI will pass!
A: What if I still want to see the docs?
B: We are pushing for --document-hidden-items to stabilize soon. So you can just simply use that!
That’s a good point.
cargo-semver-check should definitely provide a way to mark syntactically-public items as “de-facto private,” because some projects just need to do bad things and leaving them out in the cold is not helpful. But you’ve convinced me that doc(hidden)
is a poor way to do it.