bug#21943: 25.1.50; Pcvs fails to list CVS entries

bug#21943: 25.1.50; Pcvs fails to list CVS entries

[Ivan Cibrario Bertolotti]

When trying to list CVS entries using the pcvs builtin package,
for instance by means of the C-u <return> on any CVS directory
in a dired buffer, the following error message comes out:

cvs-fileinfo-from-entries: Invalid time zone specification: utc

The issue can probably be tracked down to the use of 'utc as third
argument of format-time-string at line 468 of pcvs-info.el.  Afaik,
the semantics of this argument have been changed in July 2015.

Thank you in advance for your attention,
ICB

In GNU Emacs 25.1.50.1 (x86_64-apple-darwin13.4.0, NS appkit-1265.21 Version 10.9.5 (Build 13F1112))
of 2015-11-17
Windowing system distributor 'Apple', version 10.3.1404
Configured using:
'configure --with-ns '--enable-locallisppath=/Library/Application
Support/Emacs/${version}/site-lisp:/Library/Application
Support/Emacs/site-lisp''

Configured features:
ACL LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS

Important settings:
  locale-coding-system: utf-8-unix

Major mode: Dired by name

Minor modes in effect:
  diff-auto-refine-mode: t
  type-break-mode: t
  show-paren-mode: t
  recentf-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
Loading /Users/cibrario/.recentf...done
Cleaning up the recentf list...
File /Users/cibrario/Desktop/Fat_0001/ICB_KEY#2/untitled folder/Curriculum_Bantu.doc removed from the recentf list
File /Users/cibrario/Desktop/Home/tmp/xetex/test.tex removed from the recentf list
File /Users/cibrario/Desktop/Home/tmp/xetex/test.log removed from the recentf list
Cleaning up the recentf list...done (3 removed)
For information about GNU Emacs and the GNU system, type C-h C-a.
ls does not support --dired; see ‘dired-use-ls-dired’ for more details.
cvs-fileinfo-from-entries: Invalid time zone specification: utc
Type "q" in help window to restore its previous buffer.

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug sendmail pcvs vc-cvs
pcvs-parse pcvs-info pcvs-defs ewoc psvn advice cl log-edit message
dired format-spec rfc822 mml mml-sec mm-decode mm-bodies mm-encode
mail-parse rfc2231 rfc2047 rfc2045 ietf-drums mm-util help-fns
mail-prsvr mailabbrev mail-utils gmm-utils mailheader ring pcvs-util
add-log diff-mode easy-mmode warnings server seq byte-opt gv bytecomp
byte-compile cconv cl-extra help-mode type-break paren recentf
tree-widget wid-edit cl-loaddefs pcase cl-lib cus-start cus-load
exec-path-from-shell finder-inf info tex-site package easymenu
epg-config time-date mule-util tooltip eldoc electric uniquify
ediff-hook vc-hooks lisp-float-type mwheel ns-win term/common-win
tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment
elisp-mode lisp-mode prog-mode register page menu-bar rfn-eshadow timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
frame cl-generic cham georgian utf-8-lang misc-lang vietnamese tibetan
thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek romanian
slovak czech european ethiopic indian cyrillic chinese charscript
case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote cocoa ns multi-tty
make-network-process emacs)

Memory information:
((conses 16 125698 12160)
(symbols 48 24392 0)
(miscs 40 83 253)
(strings 32 28761 5184)
(string-bytes 1 803918)
(vectors 16 17071)
(vector-slots 8 469060 3682)
(floats 8 196 75)
(intervals 56 369 14)
(buffers 976 18))


-- 
Ivan Cibrario Bertolotti             /  phone: +39 011 0905426
CNR - National Research Council     /  fax:   +39 011 0905429
IEIIT c/o Politecnico di Torino    /
Turin (Italy)                     /  mailto:ivan.cibrario@ieiit.cnr.it

bug#21943: 25.1.50; Pcvs fails to list CVS entries

[Glenn Morris]

Ivan Cibrario Bertolotti wrote:

> When trying to list CVS entries using the pcvs builtin package,
> for instance by means of the C-u <return> on any CVS directory
> in a dired buffer, the following error message comes out:
>
> cvs-fileinfo-from-entries: Invalid time zone specification: utc
>
> The issue can probably be tracked down to the use of 'utc as third
> argument of format-time-string at line 468 of pcvs-info.el.  Afaik,
> the semantics of this argument have been changed in July 2015.

Thanks for the report. The pcvs fix is obvious, but it seems to me that
this change to format-time-string should be called out in NEWS as in
incompatible one. (Obviously it would be nicer if the change were
backwards compatible.)

bug#21943: 25.1.50; Pcvs fails to list CVS entries

[Ivan Cibrario Bertolotti]

On 23 Nov 2015, at 20:01, Glenn Morris <rgm@gnu.org> wrote:
> 
> Ivan Cibrario Bertolotti wrote:
> 
>> When trying to list CVS entries using the pcvs builtin package,
>> for instance by means of the C-u <return> on any CVS directory
>> in a dired buffer, the following error message comes out:
>> 
>> cvs-fileinfo-from-entries: Invalid time zone specification: utc
>> 
>> The issue can probably be tracked down to the use of 'utc as third
>> argument of format-time-string at line 468 of pcvs-info.el.  Afaik,
>> the semantics of this argument have been changed in July 2015.
> 
> Thanks for the report. The pcvs fix is obvious, but it seems to me that
> this change to format-time-string should be called out in NEWS as in
> incompatible one. (Obviously it would be nicer if the change were
> backwards compatible.)

Thank you for your prompt reply.  As far as I know (just my 2 cents,
I’m in no way an Emacs Lisp expert) the changes introduced by
commit af32fa956267af40db61051c248597144d41521c
have been documented in NEWS, although the incompatibility has
not been explicitly called out.

More specifically, in Emacs 24.5.1, the third argument of
format-time-string was handled “as a Boolean”, that is, all non-nil
arguments were treated in the same way.

"if non-nil, means describe TIME as Universal Time; nil means
describe TIME in the local time zone”

In 25.1.50, a non-nil argument is further analyzed, looking for a
time zone rule or a few other special values.  Of them, t calls for
the old behavior.

"The optional ZONE is omitted or nil for Emacs local time, t for
Universal Time, ‘wall’ for system wall clock time, or a string as in
‘set-time-zone-rule’ for a time zone rule”

Therefore, I reckon that any call to format-time-string made in the
past with a third argument that is non-nil, not t, and does not
correspond to a valid time zone rule, is a potential source of
compatibility issues.

I do agree that the fix is obvious (most likely, just replace
any non-nil third argument with t), but it may require scanning the
code base for calls to format-time-string.

On the other hand, without introducing additional arguments, it may
be difficult to preserve backward compatibility because it is hard
to predict what programmers used as a “non-nil value” in the past.

Best regards,
ICB