bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[andrea.rossetti]

Hello,

  when I execute 

(format-time-string "%h")

I get a return value of "" instead of "nov" meaning
November, the current date month. On the contrary,
execution of

(format-time-string "%b")

correctly returns "nov". I suppose this is
due to the runtime of my Windows installation
(an ordinary Windows 7 64-bit) not supporting
C99 format modifiers of the C function "strftime".

  My conjecture came after reading of this page:
http://www.cplusplus.com/reference/ctime/strftime/ .

  I kindly ask if someone good-willed Emacs user
might see if the problem happens on his/her
Windows machine. A test on Linux could be also
a useful counterexample.

  If it affects other users too, my suggestion is to
simply add a note in the docstring of format-time-string,
saying that modifier "%h" requires a C99-compliant
runtime. 

  Thanks for your attention, kindest regards.

  Andrea




In GNU Emacs 24.3.1 (i386-mingw-nt6.1.7600)
 of 2013-03-17 on MARVIN
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SPC I SPC g e t SPC " " SPC i n s t e a d SPC o f SPC 
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e - s t r i n g SPC " % h " ) C-j <return> <return> 
<return> " % b " SPC w o r k s SPC f o r SPC m e : 
<return> <return> ( f o r m a t - t i m e - s t r i 
n g SPC " % b " ) C-j O K : SPC I SPC g o t SPC " n 
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bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Stefan Monnier]

> (format-time-string "%h")
> I get a return value of "" instead of "nov" meaning

I get "nov" here under GNU/Linux.


        Stefan

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Bastien]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> (format-time-string "%h")
>> I get a return value of "" instead of "nov" meaning
>
> I get "nov" here under GNU/Linux.

If I may chim in: someone reported the same problem on the orgmode
list, this seems limited to Windows users.

By the way, the docstring of `format-time-string' suggests that
%b and %h are equivalent: is there a difference?

-- 
 Bastien

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Eli Zaretskii]

> From: andrea.rossetti@gmail.com
> Date: Wed, 06 Nov 2013 01:05:45 +0100
> 
>   when I execute 
> 
> (format-time-string "%h")
> 
> I get a return value of "" instead of "nov" meaning
> November, the current date month. On the contrary,
> execution of
> 
> (format-time-string "%b")
> 
> correctly returns "nov". I suppose this is
> due to the runtime of my Windows installation
> (an ordinary Windows 7 64-bit) not supporting
> C99 format modifiers of the C function "strftime".

Indeed, Windows version of strftime doesn't support %h.

>   If it affects other users too, my suggestion is to
> simply add a note in the docstring of format-time-string,
> saying that modifier "%h" requires a C99-compliant
> runtime. 

Done.

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Eli Zaretskii]

> From: Bastien <bzg@altern.org>
> Date: Wed, 06 Nov 2013 07:46:18 +0100
> Cc: andrea.rossetti@gmail.com, 15816@debbugs.gnu.org
> 
> By the way, the docstring of `format-time-string' suggests that
> %b and %h are equivalent: is there a difference?

Not AFAIK.

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Rüdiger Sonderfeld]

On Wednesday 06 November 2013 12:16:00 Eli Zaretskii wrote:
> > From: andrea.rossetti@gmail.com
> > Date: Wed, 06 Nov 2013 01:05:45 +0100

> > correctly returns "nov". I suppose this is
> > due to the runtime of my Windows installation
> > (an ordinary Windows 7 64-bit) not supporting
> > C99 format modifiers of the C function "strftime".
> 
> Indeed, Windows version of strftime doesn't support %h.

I just compared the docstring to the manpage of strftime on GNU/Linux and the 
following symbols are not  ANSI C

- %C is SU
- %G,%g are TZ
- %h is SU (%b)
- %e is SU (%d with blanks)
- %u is SU
- %V is SU
- %k is TZ (%H with blanks)
- %l is TZ (%I with blanks)
- %N not in manpage or glibc manual
- %z is SU
- %s is TZ
- %D is SU ("%m/%d/%y", should not be used)
- %T is SU ("%H:%M:%S")
- %R is SU ("%H:%M")
- %r is SU ("%I:%M:%S %p")
- %t is SU (\t)
- %n is SU (\n)

(SU :: Single UNIX Specification and TZ :: Olson's timezone package)

Maybe we should not mention %h, %D, %T, %R, %r, %t, %n at all because these 
can be replaced by the portable alternatives mentioned.  The rest might be a 
bit tricky to replace.  Could you try which of them work on Windows at all?  
(Sorry I don't have a current Windows Emacs available.)

There are also %F in C99 (ISO 8601 date format) and %P (GNU extension, am/pm), 
which are not mentioned in the docstring right now.

Regards,
Rüdiger

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Andreas Schwab]

Rüdiger Sonderfeld <ruediger@c-plusplus.de> writes:

> I just compared the docstring to the manpage of strftime on GNU/Linux and the 
> following symbols are not  ANSI C

C11 has all of them (execpt %k, %l, %N, %s).

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Stefan Monnier]

> (Sorry I don't have a current Windows Emacs available.)

Not to encourage you to use the Windows version of Emacs, but I remember
once having to debug a problem where the only recipe was on Windows, and
being able to run Windows Emacs inside Wine (not perfectly, but good
enough to track the problem down).


        Stefan

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Eli Zaretskii]

> From: Rüdiger Sonderfeld <ruediger@c-plusplus.de>
> Cc: andrea.rossetti@gmail.com, 15816-done@debbugs.gnu.org
> Date: Wed, 06 Nov 2013 14:31:04 +0100
> 
> I just compared the docstring to the manpage of strftime on GNU/Linux and the 
> following symbols are not  ANSI C
> 
> - %C is SU
> - %G,%g are TZ
> - %h is SU (%b)
> - %e is SU (%d with blanks)
> - %u is SU
> - %V is SU
> - %k is TZ (%H with blanks)
> - %l is TZ (%I with blanks)
> - %N not in manpage or glibc manual
> - %z is SU
> - %s is TZ
> - %D is SU ("%m/%d/%y", should not be used)
> - %T is SU ("%H:%M:%S")
> - %R is SU ("%H:%M")
> - %r is SU ("%I:%M:%S %p")
> - %t is SU (\t)
> - %n is SU (\n)
> 
> (SU :: Single UNIX Specification and TZ :: Olson's timezone package)
> 
> Maybe we should not mention %h, %D, %T, %R, %r, %t, %n at all because these 
> can be replaced by the portable alternatives mentioned.  The rest might be a 
> bit tricky to replace.  Could you try which of them work on Windows at all?  
> (Sorry I don't have a current Windows Emacs available.)

All of them are supported, with the single exception of %r.

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Rüdiger Sonderfeld]

On Wednesday 06 November 2013 19:26:56 Eli Zaretskii wrote:
> All of them are supported, with the single exception of %r.

I'd suggest documenting %F then.  It is the date format for ISO 8601.

-- 8< ---------------------------------------------------------- >8 --

* editfns.c (Fformat_time_string): Doc fix.  (Bug#15816)

---
 src/ChangeLog | 4 ++++
 src/editfns.c | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/ChangeLog b/src/ChangeLog
index 4c3811d..7921b96 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2013-11-16  Rüdiger Sonderfeld  <ruediger@c-plusplus.de>
+
+	* editfns.c (Fformat_time_string): Doc fix.  (Bug#15816)
+
 2013-11-15  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* data.c: Work around bogus GCC diagnostic about shift count.
diff --git a/src/editfns.c b/src/editfns.c
index 277e5b6..f17b02a 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -1722,6 +1722,7 @@ TIME is specified as (HIGH LOW USEC PSEC), as returned by
 %c is the locale's date and time format.
 %x is the locale's "preferred" date format.
 %D is like "%m/%d/%y".
+%F is the ISO 8601 date format (like "%Y-%m-%d").
 
 %R is like "%H:%M", %T is like "%H:%M:%S", %r is like "%I:%M:%S %p".
 %X is the locale's "preferred" time format.
@@ -1740,7 +1741,7 @@ but takes up at least N (a number) positions.
 %EX is a locale's alternative version of %X;
 %OX is like %X, but uses the locale's number symbols.
 
-For example, to produce full ISO 8601 format, use "%Y-%m-%dT%T%z".
+For example, to produce full ISO 8601 format, use "%FT%T%z".
 
 usage: (format-time-string FORMAT-STRING &optional TIME UNIVERSAL)  */)
   (Lisp_Object format_string, Lisp_Object timeval, Lisp_Object universal)
-- 
1.8.4.2

bug#15816: 24.3; (format-time-string "%h") returns "" instead of month

[Rüdiger Sonderfeld]

Pushed the change to trunk.

Regards,
Rüdiger

On Saturday 16 November 2013 01:01:32 Rüdiger Sonderfeld wrote:
> On Wednesday 06 November 2013 19:26:56 Eli Zaretskii wrote:
> > All of them are supported, with the single exception of %r.
> 
> I'd suggest documenting %F then.  It is the date format for ISO 8601.
> 
> -- 8< ---------------------------------------------------------- >8 --
> 
> * editfns.c (Fformat_time_string): Doc fix.  (Bug#15816)
> 
> ---
>  src/ChangeLog | 4 ++++
>  src/editfns.c | 3 ++-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/src/ChangeLog b/src/ChangeLog
> index 4c3811d..7921b96 100644
> --- a/src/ChangeLog
> +++ b/src/ChangeLog
> @@ -1,3 +1,7 @@
> +2013-11-16  Rüdiger Sonderfeld  <ruediger@c-plusplus.de>
> +
> +	* editfns.c (Fformat_time_string): Doc fix.  (Bug#15816)
> +
>  2013-11-15  Paul Eggert  <eggert@cs.ucla.edu>
> 
>  	* data.c: Work around bogus GCC diagnostic about shift count.
> diff --git a/src/editfns.c b/src/editfns.c
> index 277e5b6..f17b02a 100644
> --- a/src/editfns.c
> +++ b/src/editfns.c
> @@ -1722,6 +1722,7 @@ TIME is specified as (HIGH LOW USEC PSEC), as returned
> by %c is the locale's date and time format.
>  %x is the locale's "preferred" date format.
>  %D is like "%m/%d/%y".
> +%F is the ISO 8601 date format (like "%Y-%m-%d").
> 
>  %R is like "%H:%M", %T is like "%H:%M:%S", %r is like "%I:%M:%S %p".
>  %X is the locale's "preferred" time format.
> @@ -1740,7 +1741,7 @@ but takes up at least N (a number) positions.
>  %EX is a locale's alternative version of %X;
>  %OX is like %X, but uses the locale's number symbols.
> 
> -For example, to produce full ISO 8601 format, use "%Y-%m-%dT%T%z".
> +For example, to produce full ISO 8601 format, use "%FT%T%z".
> 
>  usage: (format-time-string FORMAT-STRING &optional TIME UNIVERSAL)  */)
>    (Lisp_Object format_string, Lisp_Object timeval, Lisp_Object universal)