What do you think
#[doc(hidden)]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 thevec!macro. Changing these things shouldn’t be considered a semver violation, because they’re not really part of the API, even though thequote!macro can’t enforce it.The only other cases I can think of where I’ve seen
#[doc(hidden)]used are even bigger kludges, and the hidden items definitely aren’t part of the platonic API, like pre-#[non_exhaustive]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!
Foowas never meant to be sent to other threads, So, losingSendis not a semver- breaking change!Exhaustive enum
Baris 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-semveris still complaining about this item which I already have cfg-ed under anexp_apicrate feature (which I don’t want to rename). CI is failing.B: PRO-TIP: Just slap a
#[doc(hidden)]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.
Probably a spicy take, but I think any API being used by a macro should be made public. A macro shouldn’t be the only way to do something; it should just be a way to remove the boilerplate required to do it.
