bug#1085: 23.0.60; all-completions, try-completion inconsistent: Info-read-node-name-1

[Drew Adams]

> > I was following my analogy and thought that you did the 
> > same thing for both, using the directory part as a
> > boundary/contextual "prefix" of the relative file name.
> 
> > But IIUC, there is no invalidation of the invariants for
> > file-name completion.
> 
> Your 3rd invariant is invalidated because all-completions does not
> return the directory part of a completion.

Yes and no. If you use find-file, then yes, you're right, because it calls, in
effect, try-completion passing an absolute file name:

(try-completion "c:/mydir/icicles." 'read-file-name-internal nil) gives
"c:/mydir/icicles.el", whereas, as you say, all-completions uses relative file
names.

But if you call try-completion directly using a relative file name, then it,
just like all-completions, returns the completed relative file name - completed
in the default directory.

(try-completion "icicles." 'read-file-name-internal nil) gives "icicles.el".

That was my point. If the directory information is passed separately, not
included in the file name, then try-completion and all-completions use the same
set of completions (relative file names). There is no invalidation of the
invariant - the two coexist harmoniously - the completions for try-completion
and for all-completions are the same.

> > If you agree about that, then let's come back to "(em", 
> > which is a case, we agree, where the invariants are
> > currently invalidated.  IIUC, you say it is a
> > case where the invariants *must* be invalidated. My 
> > question is why.

I still have the same question - why?

> > Why couldn't we treat this completion the same way we treat 
> > file-name completion?
> 
> We do treat it identically.

Not if I understand correctly. Isn't it true that we use the boundary thing
(with prefix "(") for the Info file/node completion, and we don't use it for
file-name completion? And doesn't the use of that feature invalidate the
invariant?