bug#21644: 24.4; completing-read acts differently on functional collection

[Dmitry Gutov <dgutov@yandex.ru>]

On 10/15/2015 07:47 PM, Drew Adams wrote:

> Please reread what I wrote.  I said that `completing-read' is
> not mentioned in node `Basic Completion'.  And it is not.

I see, thanks. But if you want me to read your writings in whole, you 
should really try to write more concisely.

>> Basic Completion references Programmed Completion, twice.
>
> So what?

If if they want to find out about function-value COLLECTION, they'll go 
there. On the other hand, we say that the node in question has 
information about completion, collection and predicate. That includes 
the case when the collection is not a function.

> If the bug is that a user will not know the details for a
> function-valued COLLECTION argument to `completing-read' then the
> right place to send a reader for __that information__ is node
> `Programmed Completion'.

_This_ bug was about that. That doesn't mean we should fix it by 
introducing another bug.

> And I said, regarding general info about COLLECTION:
>
>    It doesn't hurt to send them to both nodes or to only
>    their parent, `Completion'.

I think that asking the user to read the whole Completion section is too 
much. Basic Completion already contains the necessary information, or 
links to it. If the user wants the overview, they can navigate to the 
parent node just as easily.