[PATCH v7 0/2] strftime: Improve the width of alternative representation for year [BZ #23758][BZ #24096]

[PATCH v7 0/2] strftime: Improve the width of alternative representation for year [BZ #23758][BZ #24096]

[TAMUKI Shoichi]

Hello,

This is the new set of patches.  I have split the patch into 2 parts.

Changes include:

Patch 1: strftime: Set the default width of "%Ey" to 2
Patch 2: strftime: Pass the additional flags from "%EY" to "%Ey"

Regards,
TAMUKI Shoichi

[PATCH v7 1/2] strftime: Set the default width of "%Ey" to 2 [BZ #23758]

[TAMUKI Shoichi]

In Japanese locales, strftime's alternative year format (%Ey) produces
the year of the current era (Japanese calendar).  A new era typically
begins when a new emperor is enthroned.  The year of the current era
is therefore usually a one- or two-digit number.

Many programs that display Japanese era dates assume that the era year
is two digits wide.  To improve how these programs display dates
during the first nine years of a new era, change %Ey to pad one-digit
numbers on the left with a zero.  This change applies to all locales.
It is expected to be harmless for other locales that use the
alternative year format (e.g. lo_LA and th_TH, in which %Ey produces
the year of the Buddhist calendar) as those calendars' year numbers
are already more than two digits wide, and this is not expected to
change.

This change needs to be in place before 2019-05-01 CE, as a new era is
scheduled to begin on that date.

ChangeLog:

	[BZ #23758]
	* manual/time.texi (strftime): Document "%Ey".
	* time/strftime_l.c (__strftime_internal): Set the default width
	padding with zero of "%Ey" to 2.
---
 NEWS              | 8 ++++++++
 manual/time.texi  | 7 +++++++
 time/strftime_l.c | 2 +-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index cc20102fda4..5152b5ed0ea 100644
--- a/NEWS
+++ b/NEWS
@@ -52,6 +52,14 @@ Major new features:
     - C-SKY ABIV2 soft-float little-endian
     - C-SKY ABIV2 hard-float little-endian
 
+* strftime's default formatting of a locale's alternative year (%Ey)
+  has been changed to zero-pad the year to a minimum of two digits,
+  like %y.  This improves the display of Japanese era years during
+  the first nine years of a new era, and is expected to be harmless
+  for all other locales (only Japanese locales regularly have
+  alternative year numbers less than 10).  Zero-padding can be
+  overridden with the '-' or '_' flags (which are GNU extensions).
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The glibc.tune tunable namespace has been renamed to glibc.cpu and the
diff --git a/manual/time.texi b/manual/time.texi
index fd7781c5317..03a8a0e10fc 100644
--- a/manual/time.texi
+++ b/manual/time.texi
@@ -1568,6 +1568,13 @@ The preferred time of day representation for the current locale.
 The year without a century as a decimal number (range @code{00} through
 @code{99}).  This is equivalent to the year modulo 100.
 
+If the @code{E} modifier is specified (@code{%Ey}), instead produces
+the year number according to a locale-specific alternative calendar.
+Unlike @code{%y}, the number is @emph{not} reduced modulo 100.
+However, by default it is zero-padded to a minimum of two digits (this
+can be overridden by an explicit field width or by the @code{_} and
+@code{-} flags).
+
 @item %Y
 The year as a decimal number, using the Gregorian calendar.  Years
 before the year @code{1} are numbered @code{0}, @code{-1}, and so on.
diff --git a/time/strftime_l.c b/time/strftime_l.c
index 7ba4179de3e..cbe08e7afb4 100644
--- a/time/strftime_l.c
+++ b/time/strftime_l.c
@@ -1294,7 +1294,7 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 	      if (era)
 		{
 		  int delta = tp->tm_year - era->start_date[0];
-		  DO_NUMBER (1, (era->offset
+		  DO_NUMBER (2, (era->offset
 				 + delta * era->absolute_direction));
 		}
 #else
-- 
2.12.2

[PATCH v7 2/2] strftime: Pass the additional flags from "%EY" to "%Ey" [BZ #24096]

[TAMUKI Shoichi]

The full representation of the alternative calendar year (%EY)
typically includes an internal use of %Ey.  As a GNU extension, apply
any flags on %EY (e.g. "%-EY", "%_Ey") to the internal %Ey, allowing
users of %EY to control how the year is padded.

ChangeLog:

	[BZ #24096]
	* manual/time.texi (strftime): Document "%EC" and "%EY".
	* time/Makefile: Add tst-strftime2 to tests.  Also add ja_JP.UTF-8,
	lo_LA.UTF-8, and th_TH.UTF-8 to LOCALES.
	* time/strftime_l.c (__strftime_internal): Add argument yr_spec to
	override padding for "%Ey".
	If an optional flag ('_' or '-') is specified to "%EY", interpret the
	"%Ey" in the subformat as if decorated with that flag.
	* time/tst-strftime2.c: New file.
---
 NEWS                 |   4 ++
 manual/time.texi     |  11 +++++
 time/Makefile        |   5 +-
 time/strftime_l.c    |  20 +++++---
 time/tst-strftime2.c | 132 +++++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 163 insertions(+), 9 deletions(-)
 create mode 100644 time/tst-strftime2.c

diff --git a/NEWS b/NEWS
index 5152b5ed0ea..95e15c86766 100644
--- a/NEWS
+++ b/NEWS
@@ -60,6 +60,10 @@ Major new features:
   alternative year numbers less than 10).  Zero-padding can be
   overridden with the '-' or '_' flags (which are GNU extensions).
 
+* As a GNU extension, the '-' and '_' flags can now be applied to %EY
+  to control how the year number is formatted; they have the same
+  effect that they would on %Ey.
+
 Deprecated and removed features, and other changes affecting compatibility:
 
 * The glibc.tune tunable namespace has been renamed to glibc.cpu and the
diff --git a/manual/time.texi b/manual/time.texi
index 03a8a0e10fc..b2867482d31 100644
--- a/manual/time.texi
+++ b/manual/time.texi
@@ -1393,6 +1393,10 @@ The preferred calendar time representation for the current locale.
 The century of the year.  This is equivalent to the greatest integer not
 greater than the year divided by 100.
 
+If the @code{E} modifier is specified (@code{%EC}), instead produces
+the name of the period for the current year (e.g.@: an era name) in
+the locale's alternative calendar.
+
 This format was first standardized by POSIX.2-1992 and by @w{ISO C99}.
 
 @item %d
@@ -1579,6 +1583,13 @@ can be overridden by an explicit field width or by the @code{_} and
 The year as a decimal number, using the Gregorian calendar.  Years
 before the year @code{1} are numbered @code{0}, @code{-1}, and so on.
 
+If the @code{E} modifier is specified (@code{%EY}), instead produces a
+complete representation of the year according to the locale's
+alternative calendar.  Generally this will be some combination of the
+information produced by @code{%EC} and @code{Ey}.  As a GNU extension,
+the formatting flags @code{_} or @code{-} may be used with this
+conversion specifier; they affect how the year number is printed.
+
 @item %z
 @w{RFC 822}/@w{ISO 8601:1988} style numeric time zone (e.g.,
 @code{-0600} or @code{+0100}), or nothing if no time zone is
diff --git a/time/Makefile b/time/Makefile
index d23ba2dee6e..5c6304ece1d 100644
--- a/time/Makefile
+++ b/time/Makefile
@@ -43,13 +43,14 @@ tests	:= test_time clocktest tst-posixtz tst-strptime tst_wcsftime \
 	   tst-getdate tst-mktime tst-mktime2 tst-ftime_l tst-strftime \
 	   tst-mktime3 tst-strptime2 bug-asctime bug-asctime_r bug-mktime1 \
 	   tst-strptime3 bug-getdate1 tst-strptime-whitespace tst-ftime \
-	   tst-tzname tst-y2039 bug-mktime4
+	   tst-tzname tst-y2039 bug-mktime4 tst-strftime2
 
 include ../Rules
 
 ifeq ($(run-built-tests),yes)
 LOCALES := de_DE.ISO-8859-1 en_US.ISO-8859-1 ja_JP.EUC-JP fr_FR.UTF-8 \
-	   es_ES.UTF-8 pl_PL.UTF-8 ru_RU.UTF-8
+	   es_ES.UTF-8 pl_PL.UTF-8 ru_RU.UTF-8 \
+	   ja_JP.UTF-8 lo_LA.UTF-8 th_TH.UTF-8
 include ../gen-locales.mk
 
 $(objpfx)tst-ftime_l.out: $(gen-locales)
diff --git a/time/strftime_l.c b/time/strftime_l.c
index cbe08e7afb4..12d7c0e8744 100644
--- a/time/strftime_l.c
+++ b/time/strftime_l.c
@@ -434,7 +434,7 @@ static CHAR_T const month_name[][10] =
 #endif
 
 static size_t __strftime_internal (CHAR_T *, size_t, const CHAR_T *,
-				   const struct tm *, bool *
+				   const struct tm *, int *, bool *
 				   ut_argument_spec
 				   LOCALE_PARAM) __THROW;
 
@@ -456,8 +456,9 @@ my_strftime (CHAR_T *s, size_t maxsize, const CHAR_T *format,
   tmcopy = *tp;
   tp = &tmcopy;
 #endif
+  int yr_spec = 0;		/* Override padding for "%Ey".  */
   bool tzset_called = false;
-  return __strftime_internal (s, maxsize, format, tp, &tzset_called
+  return __strftime_internal (s, maxsize, format, tp, &yr_spec, &tzset_called
 			      ut_argument LOCALE_ARG);
 }
 #ifdef _LIBC
@@ -466,7 +467,7 @@ libc_hidden_def (my_strftime)
 
 static size_t
 __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
-		     const struct tm *tp, bool *tzset_called
+		     const struct tm *tp, int *yr_spec, bool *tzset_called
 		     ut_argument_spec LOCALE_PARAM)
 {
 #if defined _LIBC && defined USE_IN_EXTENDED_LOCALE_MODEL
@@ -838,11 +839,12 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 	  {
 	    CHAR_T *old_start = p;
 	    size_t len = __strftime_internal (NULL, (size_t) -1, subfmt,
-					      tp, tzset_called ut_argument
-					      LOCALE_ARG);
+					      tp, yr_spec, tzset_called
+					      ut_argument LOCALE_ARG);
 	    add (len, __strftime_internal (p, maxsize - i, subfmt,
-					   tp, tzset_called ut_argument
-					   LOCALE_ARG));
+					   tp, yr_spec, tzset_called
+					   ut_argument LOCALE_ARG));
+	    *yr_spec = 0;
 
 	    if (to_uppcase)
 	      while (old_start < p)
@@ -1273,6 +1275,8 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 # else
 		  subfmt = era->era_format;
 # endif
+		  if (pad != 0)
+		    *yr_spec = pad;
 		  goto subformat;
 		}
 #else
@@ -1294,6 +1298,8 @@ __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 	      if (era)
 		{
 		  int delta = tp->tm_year - era->start_date[0];
+		  if (*yr_spec != 0)
+		    pad = *yr_spec;
 		  DO_NUMBER (2, (era->offset
 				 + delta * era->absolute_direction));
 		}
diff --git a/time/tst-strftime2.c b/time/tst-strftime2.c
new file mode 100644
index 00000000000..57d2144c83c
--- /dev/null
+++ b/time/tst-strftime2.c
@@ -0,0 +1,132 @@
+/* Verify the behavior of strftime on alternative representation for
+   year.
+
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <locale.h>
+#include <time.h>
+#include <stdio.h>
+#include <string.h>
+
+static const char *locales[] = { "ja_JP.UTF-8", "lo_LA.UTF-8", "th_TH.UTF-8" };
+
+static const char *formats[] = { "%EY", "%_EY", "%-EY" };
+
+static const struct
+{
+  const int d, m, y;
+} dates[] =
+  {
+    { 1, 3, 88 },
+    { 7, 0, 89 },
+    { 8, 0, 89 },
+    { 1, 3, 90 },
+    { 1, 3, 97 },
+    { 1, 3, 98 }
+  };
+
+static char ref[3][3][6][100];
+
+static void
+mkreftable (void)
+{
+  int i, j, k;
+  char era[10];
+  static const int yrj[] = { 63, 64, 1, 2, 9, 10 };
+  static const int yrb[] = { 2531, 2532, 2532, 2533, 2540, 2541 };
+
+  for (i = 0; i < array_length (locales); i++)
+    for (j = 0; j < array_length (formats); j++)
+      for (k = 0; k < array_length (dates); k++)
+	{
+	  if (i == 0)
+	    {
+	      sprintf (era, "%s", (k < 2) ? "\xe6\x98\xad\xe5\x92\x8c"
+					  : "\xe5\xb9\xb3\xe6\x88\x90");
+	      if (yrj[k] == 1)
+		sprintf (ref[i][j][k], "%s\xe5\x85\x83\xe5\xb9\xb4", era);
+	      else
+		{
+		  if (j == 0)
+		    sprintf (ref[i][j][k], "%s%02d\xe5\xb9\xb4", era, yrj[k]);
+		  else if (j == 1)
+		    sprintf (ref[i][j][k], "%s%2d\xe5\xb9\xb4", era, yrj[k]);
+		  else
+		    sprintf (ref[i][j][k], "%s%d\xe5\xb9\xb4", era, yrj[k]);
+		}
+	    }
+	  else if (i == 1)
+	    {
+	      sprintf (era, "\xe0\xba\x9e\x2e\xe0\xba\xaa\x2e ");
+	      sprintf (ref[i][j][k], "%s%d", era, yrb[k]);
+	    }
+	  else
+	    {
+	      sprintf (era, "\xe0\xb8\x9e\x2e\xe0\xb8\xa8\x2e ");
+	      sprintf (ref[i][j][k], "%s%d", era, yrb[k]);
+	    }
+	}
+}
+
+static int
+do_test (void)
+{
+  int i, j, k, result = 0;
+  struct tm ttm;
+  char date[11], buf[100];
+  size_t r, e;
+
+  mkreftable ();
+  for (i = 0; i < array_length (locales); i++)
+    {
+      if (setlocale (LC_ALL, locales[i]) == NULL)
+	{
+	  printf ("locale %s does not exist, skipping...\n", locales[i]);
+	  continue;
+	}
+      printf ("[%s]\n", locales[i]);
+      for (j = 0; j < array_length (formats); j++)
+	{
+	  for (k = 0; k < array_length (dates); k++)
+	    {
+	      ttm.tm_mday = dates[k].d;
+	      ttm.tm_mon  = dates[k].m;
+	      ttm.tm_year = dates[k].y;
+	      strftime (date, sizeof (date), "%F", &ttm);
+	      r = strftime (buf, sizeof (buf), formats[j], &ttm);
+	      e = strlen (ref[i][j][k]);
+	      printf ("%s\t\"%s\"\t\"%s\"", date, formats[j], buf);
+	      if (strcmp (buf, ref[i][j][k]) != 0)
+		{
+		  printf ("\tshould be \"%s\"", ref[i][j][k]);
+		  if (r != e)
+		    printf ("\tgot: %zu, expected: %zu", r, e);
+		  result = 1;
+		}
+	      else
+		printf ("\tOK");
+	      putchar ('\n');
+	    }
+	  putchar ('\n');
+	}
+    }
+  return result;
+}
+
+#include <support/test-driver.c>
-- 
2.12.2

Re: [PATCH v7 1/2] strftime: Set the default width of "%Ey" to 2 [BZ #23758]

[Rafal Luzynski]

17.01.2019 07:38 TAMUKI Shoichi <tamuki@linet.gr.jp> wrote:
> In Japanese locales, strftime's alternative year format (%Ey) produces
> the year of the current era (Japanese calendar).

As I wrote in my previous email, the term "Japanese calendar" may be
incorrect here.

Now I can see that neither of our comments may be correct.  "%Ey" produces
the number of the year within the current era.  It says which (numbered)
year of the current era is now.  Is "nengo" a correct name for this?
Should we maybe drop this parentheses completely, including its content?

I don't quote the rest of your patch here as it looks correct to me,
looking at previous comments from Zack and Paul.  Please rethink this
minor issue in the commit message and/or maybe let's wait for Zack's
or Paul's comment about it and it will be OK for me to commit this.

Regards,

Rafal

Re: [PATCH v7 2/2] strftime: Pass the additional flags from "%EY" to "%Ey" [BZ #24096]

[Rafal Luzynski]

17.01.2019 07:39 TAMUKI Shoichi <tamuki@linet.gr.jp> wrote:
> The full representation of the alternative calendar year (%EY)
> typically includes an internal use of %Ey.  As a GNU extension, apply
> any flags on %EY (e.g. "%-EY", "%_Ey") to the internal %Ey, allowing
> users of %EY to control how the year is padded.

This is correct according to what Zack wrote.

> ChangeLog:
> 
> 	[BZ #24096]
> 	* manual/time.texi (strftime): Document "%EC" and "%EY".

OK

> 	* time/Makefile: Add tst-strftime2 to tests.  Also add ja_JP.UTF-8,
> 	lo_LA.UTF-8, and th_TH.UTF-8 to LOCALES.

This should be:

	* time/Makefile (tests): Add tst-strftime2.
	(LOCALES): Add ja_JP.UTF-8, lo_LA.UTF-8, and th_TH.UTF-8.

> 	* time/strftime_l.c (__strftime_internal): Add argument yr_spec to
> 	override padding for "%Ey".
> 	If an optional flag ('_' or '-') is specified to "%EY", interpret the
> 	"%Ey" in the subformat as if decorated with that flag.
> 	* time/tst-strftime2.c: New file.

The rest of the commit message and the documentation changes are correct,
according to what Zack and Paul wrote before.  I need more time to analyze
the "yr_spec" issue.  I believe that your code is working, what we are
discussing here is only how (and whether) to do it better.

Regards,

Rafal

Re: [PATCH v6 1/2] strftime: Set the default width of "%Ey" to 2 [BZ #23758]

[TAMUKI Shoichi]

Hello Rafal,

From: Rafal Luzynski <digitalfreak@lingonborough.com>
Subject: Re: [PATCH v7 1/2] strftime: Set the default width of "%Ey" to 2 [BZ #23758]
Date: Thu, 17 Jan 2019 19:11:53 +0100 (CET)

> > In Japanese locales, strftime's alternative year format (%Ey) produces
> > the year of the current era (Japanese calendar).
> 
> As I wrote in my previous email, the term "Japanese calendar" may be
> incorrect here.

I think that (Japanese numeric era year) would be more appropriate.

> Now I can see that neither of our comments may be correct.  "%Ey" produces
> the number of the year within the current era.  It says which (numbered)
> year of the current era is now.  Is "nengo" a correct name for this?
> Should we maybe drop this parentheses completely, including its content?

Not correct, "nengo" (or "gengo") means "era name" (%EC).  So, We may
rather drop this parentheses completely.

> I don't quote the rest of your patch here as it looks correct to me,
> looking at previous comments from Zack and Paul.  Please rethink this
> minor issue in the commit message and/or maybe let's wait for Zack's
> or Paul's comment about it and it will be OK for me to commit this.

OK, I am going to rethink the minor issue including the quote issue.
I will try to match existing sentences as much as possible.

Regards,
TAMUKI Shoichi