Make hasdoc public

[jariji]

Making Docs.hasdoc public per @LilithHafner #52139 (comment).

[stevengj]

Should it simply be exported?

(Note that even if you add export hasdoc here, it still won't be re-exported by Base by default.)

[jariji]

Now exporting undocumented_names from Docs too, per #52708 (comment).

[stevengj]

I also fixed the docstring to refer to "public" symbols rather than "exported" symbols, following #52413 (comment) by @LilithHafner

[LilithHafner]

I don't see much advantage of exporting from a submodule (historically, I'm guessing the primary uses were to mark the symbols public and when a symbol was previously defined in Base and moved to a submodule)

[jariji]

In favor of export:

• people who do using Base.Docs can get the convenience they want.
• export is the most common way of making something public, so without a particular reason against, it seems good to keep with the normal practice. It's nice to have a single way of doing things that works as often as possible.

[stevengj]

If we are going to export doc and @var and @text_str (some of which aren't even documented), it doesn't make sense to me not to export hasdoc and documented_symbols (which are much more likely to be used outside of Base). And, after all, people can do using Base.Docs or using .Docs` as @jariji pointed out.

[stevengj]

(After this, I think we need to make a concerted effort to get @test isempty(undocumented_symbols(Foo)) to pass for stdlib modules and documented submodules. See #52723 and #52725.)

[stevengj]

Bump.

[LilithHafner]

The declared semantics of undocumented_names (based on isidentifier) don't seem viable to me right now (e.g. it excludes macros and operators) so we shouldn't publicize them.

c.f. #52413 (comment)

The original commit (make hasdoc public) is definitely mergable, though.

[stevengj]

@LilithHafner, undocumented_names was already changed (at your request) to include all public symbols, including macros and operators, that don't begin with # (to exclude generated internal symbols, ala gensym), don't you remember? #52743

(This PR just needs to be updated merge the latest master branch and fix merge conflicts.)

[LilithHafner]

don't you remember?

Clearly not, lol. You are quite right.