bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

[Aidan Kehoe]

This bug report will be sent to the Bug-GNU-Emacs mailing list
and the GNU bug tracker at debbugs.gnu.org.  Please check that
the From: line contains a valid email address.  After a delay of up
to one day, you should receive an acknowledgement at that address.

Please write in English if possible, as the Emacs maintainers
usually do not have translators for other languages.

Please describe exactly what actions triggered the bug, and
the precise symptoms of the bug.  If you can, give a recipe
starting from `emacs -Q':

Hello there,

Recipe to trigger the problem:

 (try-completion "del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone)))
 => t ;; as expected and documented

 (all-completions "del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone)))
 => ("del-alist") ;; as expected and documented

 (test-completion "del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone)))
 =>
Debugger entered--Lisp error: (wrong-type-argument stringp del-alist)
  test-completion("del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone ...)))

This is unexpected, inconsistent, and not documented; it should return t, as
it does if the hash table key is a string.

Happy New Year,

Aidan

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
For information about debugging Emacs, please read the file
/Sources/emacs/etc/DEBUG.


In GNU Emacs 24.0.92.1 (i386-apple-darwin10.8.0, GTK+ Version 2.22.1)
 of 2011-12-30 on bonbon
Windowing system distributor `The X.Org Foundation', version 11.0.10402000
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  value of $LANG: de_DE.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Fundamental

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-- 
‘Iodine deficiency was endemic in parts of the UK until, through what has been
described as “an unplanned and accidental public health triumph”, iodine was
added to cattle feed to improve milk production in the 1930s.’
(EN Pearce, Lancet, June 2011)

bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

[Stefan Monnier]

>  (try-completion "del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone)))
>  => t ;; as expected and documented

>  (all-completions "del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone)))
>  => ("del-alist") ;; as expected and documented

These are bugs.  The Elisp manual is pretty clear about it:

     If COLLECTION is a hash table, then the keys that are strings are
     the possible completions.  Other keys are ignored.


-- Stefan

bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

[Aidan Kehoe]

 Ar an chéad lá de mí Eanair, scríobh Stefan Monnier: 

 > >  (try-completion "del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone)))
 > >  => t ;; as expected and documented
 > 
 > >  (all-completions "del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone)))
 > >  => ("del-alist") ;; as expected and documented
 > 
 > These are bugs.  The Elisp manual is pretty clear about it:
 > 
 >      If COLLECTION is a hash table, then the keys that are strings are
 >      the possible completions.  Other keys are ignored.

And the docstrings of #'try-completion and #'all-completion are equally
clear, and contradict that. They both say the following:

‘If COLLECTION is a hash-table, all the keys that are strings or symbols
are the possible completions.’

-- 
‘Iodine deficiency was endemic in parts of the UK until, through what has been
described as “an unplanned and accidental public health triumph”, iodine was
added to cattle feed to improve milk production in the 1930s.’
(EN Pearce, Lancet, June 2011)

bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

[Stefan Monnier]

>> If COLLECTION is a hash table, then the keys that are strings are
>> the possible completions.  Other keys are ignored.

> And the docstrings of #'try-completion and #'all-completion are equally
> clear, and contradict that. They both say the following:

> ‘If COLLECTION is a hash-table, all the keys that are strings or symbols
> are the possible completions.’

Right.  So we clearly need to fix the doc.  Maybe also the code.  But in
the mean time I think the contradictory docs basically mean "stay away
from symbols as keys for completion hash-tables".


        Stefan

bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

[Aidan Kehoe]

 Ar an chéad lá de mí Eanair, scríobh Stefan Monnier: 

 > >  (try-completion "del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone)))
 > >  => t ;; as expected and documented
 > 
 > >  (all-completions "del-alist" #s(hash-table size 145 test equal rehash-size 1.5 rehash-threshold 0.8 data (del-alist hello "delay-mode-hooks" everyone "delete" everyone)))
 > >  => ("del-alist") ;; as expected and documented
 > 
 > These are bugs.  The Elisp manual is pretty clear about it:
 > 
 >      If COLLECTION is a hash table, then the keys that are strings are
 >      the possible completions.  Other keys are ignored.

Also, throwing an error on encountering a symbol key (as #'test-completion
does) is not what that paragraph describes.

-- 
‘Iodine deficiency was endemic in parts of the UK until, through what has been
described as “an unplanned and accidental public health triumph”, iodine was
added to cattle feed to improve milk production in the 1930s.’
(EN Pearce, Lancet, June 2011)

bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

[Noam Postavsky]

[-- Attachment #1: Type: text/plain, Size: 170 bytes --]

tag 10416 + patch
quit

In 24.5 the 3rd case is fixed, but the docs are still contradictory as
of 25.0.94. Here is a patch to make manual agree with code and
docstrings.

[-- Attachment #2: 0001-Fix-documentation-of-completion-functions.patch --]
[-- Type: text/x-diff, Size: 1208 bytes --]

From dc25b98bf90b68b78c8b3baf4dcc0bbc609bd2d2 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Tue, 7 Jun 2016 23:37:05 -0400
Subject: [PATCH] Fix documentation of completion functions

So that the behavior matches the match code (and docstrings).

* doc/lispref/minibuf.texi (Basic Completion): Symbol keys of hash table
are not ignored.
---
 doc/lispref/minibuf.texi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/lispref/minibuf.texi b/doc/lispref/minibuf.texi
index 6f41090..1fa2536 100644
--- a/doc/lispref/minibuf.texi
+++ b/doc/lispref/minibuf.texi
@@ -733,8 +733,8 @@ Basic Completion
 If @var{collection} is an obarray (@pxref{Creating Symbols}), the names
 of all symbols in the obarray form the set of permissible completions.
 
-If @var{collection} is a hash table, then the keys that are strings
-are the possible completions.  Other keys are ignored.
+If @var{collection} is a hash table, then the keys that are strings or
+symbols are the possible completions.  Other keys are ignored.
 
 You can also use a function as @var{collection}.  Then the function is
 solely responsible for performing completion; @code{try-completion}
-- 
2.8.0

bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

[Noam Postavsky]

The code has meanwhile been changed to handle symbol hash keys in 24.4
(a8036e40 "* src/minibuf.c (Ftest_completion): Ignore
non-string/symbol keys in hash tables.").

Should we update the manual to match the docstring and code now?

bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

[Eli Zaretskii]

> From: Noam Postavsky <npostavs@users.sourceforge.net>
> Date: Sat, 18 Jun 2016 12:32:07 -0400
> Cc: Aidan Kehoe <kehoea@parhasard.net>,
> 	Stefan Monnier <monnier@iro.umontreal.ca>
> 
> Should we update the manual to match the docstring and code now?

Yes, as always.

Thanks.

bug#10416: 24.0.92; #'test-completion is inconsistent with symbol hash keys in COLLECTION

[Noam Postavsky]

Version: 24.4

On Sat, Jun 18, 2016 at 1:20 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Noam Postavsky <npostavs@users.sourceforge.net>
>> Date: Sat, 18 Jun 2016 12:32:07 -0400
>> Cc: Aidan Kehoe <kehoea@parhasard.net>,
>>       Stefan Monnier <monnier@iro.umontreal.ca>
>>
>> Should we update the manual to match the docstring and code now?
>
> Yes, as always.
>
> Thanks.

Okay, I pushed the manual patch to emacs-25 (d1efbafd).