The default format of `today_fmt` and `html_last_updated_fmt` is back to strftime format again

`html_last_updated_fmt` is commonly used for non date formatting. But
LDML is difficult to represent them from its characteristics.

Now we moved to strftime format again (ref: #2394).

10 files changed, 49 insertions, 27 deletions

diff --git a/CHANGES b/CHANGES
index 472ca6e81..d78473a84 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,13 @@
 Release 1.4.1 (in development)
 ==============================
 
+Incompatible changes
+--------------------
+
+* The default format of `today_fmt` and `html_last_updated_fmt` is back to
+  strftime format again.  Locale Date Markup Language is also supported for
+  backward compatibility until Sphinx-1.5.
+
 Translations
 ------------
 
diff --git a/doc/config.rst b/doc/config.rst
index c87db8dd3..9fc086955 100644
--- a/doc/config.rst
+++ b/doc/config.rst
@@ -330,13 +330,12 @@ Project information
    replacement for ``|today|``.
 
    * If you set :confval:`today` to a non-empty value, it is used.
-   * Otherwise, the current time is formatted using `Locale Data Markup Language
-     <http://unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns>`_
-     and the format given in :confval:`today_fmt`.
+   * Otherwise, the current time is formatted using :func:`time.strftime` and
+     the format given in :confval:`today_fmt`.
 
-   The default is no :confval:`today` and a :confval:`today_fmt` of ``'MMMM dd,
-   YYYY'`` (or, if translation is enabled with :confval:`language`, an
-   equivalent %format for the selected locale).
+   The default is no :confval:`today` and a :confval:`today_fmt` of ``'%B %d,
+   %Y'`` (or, if translation is enabled with :confval:`language`, an equivalent
+   format for the selected locale).
 
    .. versionchanged:: 1.4
 
@@ -344,6 +343,12 @@ Project information
       Language. strftime format is also supported for backward compatibility
       until Sphinx-1.5.
 
+   .. versionchanged:: 1.4.1
+
+      Format specification was changed again from Locale Data Markup Language
+      to strftime.  LDML format is also supported for backward compatibility
+      until Sphinx-1.5.
+
 .. confval:: highlight_language
 
    The default language to highlight source code in.  The default is
@@ -696,9 +701,8 @@ that use Sphinx's HTMLWriter class.
 .. confval:: html_last_updated_fmt
 
    If this is not None, a 'Last updated on:' timestamp is inserted
-   at every page bottom, using the given `Locale Data Markup Language
-   <http://unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns>`_
-   format.  The empty string is equivalent to ``'MMM dd, YYYY'`` (or a
+   at every page bottom, using the given :func:`strftime` format.
+   The empty string is equivalent to ``'%b %d, %Y'`` (or a
    locale-dependent equivalent).
 
    .. versionchanged:: 1.4
@@ -707,6 +711,13 @@ that use Sphinx's HTMLWriter class.
       Language. strftime format is also supported for backward compatibility
       until Sphinx-1.5.
 
+   .. versionchanged:: 1.4.1
+
+      Format specification was changed again from Locale Data Markup Language
+      to strftime.  LDML format is also supported for backward compatibility
+      until Sphinx-1.5.
+
+
 .. confval:: html_use_smartypants
 
    If true, `SmartyPants <http://daringfireball.net/projects/smartypants/>`_
diff --git a/sphinx/builders/epub.py b/sphinx/builders/epub.py
index 265421d2c..cc839d757 100644
--- a/sphinx/builders/epub.py
+++ b/sphinx/builders/epub.py
@@ -530,7 +530,7 @@ class EpubBuilder(StandaloneHTMLBuilder):
         metadata['copyright'] = self.esc(self.config.epub_copyright)
         metadata['scheme'] = self.esc(self.config.epub_scheme)
         metadata['id'] = self.esc(self.config.epub_identifier)
-        metadata['date'] = self.esc(format_date('YYYY-MM-dd', language=self.config.language,
+        metadata['date'] = self.esc(format_date('%Y-%m-%d', language=self.config.language,
                                                 warn=self.warn))
         metadata['files'] = files
         metadata['spine'] = spine
diff --git a/sphinx/builders/html.py b/sphinx/builders/html.py
index 1b3db1402..f541daa1a 100644
--- a/sphinx/builders/html.py
+++ b/sphinx/builders/html.py
@@ -292,7 +292,7 @@ class StandaloneHTMLBuilder(Builder):
         # typically doesn't include the time of day
         lufmt = self.config.html_last_updated_fmt
         if lufmt is not None:
-            self.last_updated = format_date(lufmt or _('MMM dd, YYYY'),
+            self.last_updated = format_date(lufmt or _('%b %d, %Y'),
                                             language=self.config.language,
                                             warn=self.warn)
         else:
diff --git a/sphinx/transforms.py b/sphinx/transforms.py
index 7272d3b19..2e3fb7f0b 100644
--- a/sphinx/transforms.py
+++ b/sphinx/transforms.py
@@ -54,7 +54,7 @@ class DefaultSubstitutions(Transform):
                 text = config[refname]
                 if refname == 'today' and not text:
                     # special handling: can also specify a strftime format
-                    text = format_date(config.today_fmt or _('MMMM dd, YYYY'),
+                    text = format_date(config.today_fmt or _('%b %d, %Y'),
                                        language=config.language, warn=env.warn)
                 ref.replace_self(nodes.Text(text, text))
 
diff --git a/sphinx/util/i18n.py b/sphinx/util/i18n.py
index 5d98b115c..16fa7a21c 100644
--- a/sphinx/util/i18n.py
+++ b/sphinx/util/i18n.py
@@ -179,13 +179,13 @@ def format_date(format, date=None, language=None, warn=None):
         else:
             date = datetime.now()
 
-    if '%' not in format:
+    if re.match('EEE|MMM|dd|DDD|MM|WW|medium|YY', format):
         # consider the format as babel's
-        return babel_format_date(date, format, locale=language, warn=warn)
-    else:
-        warnings.warn('ustrftime format support will be dropped at Sphinx-1.5',
+        warnings.warn('LDML format support will be dropped at Sphinx-1.5',
                       DeprecationWarning)
 
+        return babel_format_date(date, format, locale=language, warn=warn)
+    else:
         # consider the format as ustrftime's and try to convert it to babel's
         result = []
         tokens = re.split('(%.)', format)
diff --git a/sphinx/writers/latex.py b/sphinx/writers/latex.py
index 2e9cc784e..6019d04ed 100644
--- a/sphinx/writers/latex.py
+++ b/sphinx/writers/latex.py
@@ -371,8 +371,7 @@ class LaTeXTranslator(nodes.NodeVisitor):
         if builder.config.today:
             self.elements['date'] = builder.config.today
         else:
-            self.elements['date'] = format_date(builder.config.today_fmt or
-                                                _('MMMM dd, YYYY'),
+            self.elements['date'] = format_date(builder.config.today_fmt or _('%b %d, %Y'),
                                                 language=builder.config.language)
         if builder.config.latex_logo:
             self.elements['logo'] = '\\includegraphics{%s}\\par' % \
diff --git a/sphinx/writers/manpage.py b/sphinx/writers/manpage.py
index 2651ec2e4..223ed78fd 100644
--- a/sphinx/writers/manpage.py
+++ b/sphinx/writers/manpage.py
@@ -97,8 +97,7 @@ class ManualPageTranslator(BaseTranslator):
         if builder.config.today:
             self._docinfo['date'] = builder.config.today
         else:
-            self._docinfo['date'] = format_date(builder.config.today_fmt or
-                                                _('MMMM dd, YYYY'),
+            self._docinfo['date'] = format_date(builder.config.today_fmt or _('%b %d, %Y'),
                                                 language=builder.config.language)
         self._docinfo['copyright'] = builder.config.copyright
         self._docinfo['version'] = builder.config.version
diff --git a/sphinx/writers/texinfo.py b/sphinx/writers/texinfo.py
index fc7d31534..978d56c0b 100644
--- a/sphinx/writers/texinfo.py
+++ b/sphinx/writers/texinfo.py
@@ -218,8 +218,7 @@ class TexinfoTranslator(nodes.NodeVisitor):
             'project': self.escape(self.builder.config.project),
             'copyright': self.escape(self.builder.config.copyright),
             'date': self.escape(self.builder.config.today or
-                                format_date(self.builder.config.today_fmt or
-                                            _('MMMM dd, YYYY'),
+                                format_date(self.builder.config.today_fmt or _('%b %d, %Y'),
                                             language=self.builder.config.language))
         })
         # title
diff --git a/tests/test_util_i18n.py b/tests/test_util_i18n.py
index a534b2771..5a54cbb80 100644
--- a/tests/test_util_i18n.py
+++ b/tests/test_util_i18n.py
@@ -169,6 +169,7 @@ def test_get_catalogs_with_compact(dir):
 def test_format_date():
     date = datetime.date(2016, 2, 7)
 
+    # default format
     format = None
     assert i18n.format_date(format, date=date) == 'Feb 7, 2016'
     assert i18n.format_date(format, date=date, language='') == 'Feb 7, 2016'
@@ -177,6 +178,7 @@ def test_format_date():
     assert i18n.format_date(format, date=date, language='ja') == '2016/02/07'
     assert i18n.format_date(format, date=date, language='de') == '07.02.2016'
 
+    # strftime format
     format = '%B %d, %Y'
     assert i18n.format_date(format, date=date) == 'February 07, 2016'
     assert i18n.format_date(format, date=date, language='') == 'February 07, 2016'
@@ -185,14 +187,19 @@ def test_format_date():
     assert i18n.format_date(format, date=date, language='ja') == u'2月 07, 2016'
     assert i18n.format_date(format, date=date, language='de') == 'Februar 07, 2016'
 
-    # invalid date format
+    # LDML format
+    format = 'MMM dd, YYYY'
+    assert i18n.format_date(format, date=date) == 'Feb 07, 2016'
+    assert i18n.format_date(format, date=date, language='') == 'Feb 07, 2016'
+    assert i18n.format_date(format, date=date, language='unknown') == 'Feb 07, 2016'
+    assert i18n.format_date(format, date=date, language='en') == 'Feb 07, 2016'
+    assert i18n.format_date(format, date=date, language='ja') == u'2月 07, 2016'
+    assert i18n.format_date(format, date=date, language='de') == 'Feb. 07, 2016'
+
+    # raw string
     format = 'Mon Mar 28 12:37:08 2016, commit 4367aef'
     assert i18n.format_date(format, date=date) == format
 
-    # quoted format
-    quoted_format = "'Mon Mar 28 12:37:08 2016, commit 4367aef'"
-    assert i18n.format_date(quoted_format, date=date) == format
-
 
 def test_get_filename_for_language():
     app = TestApp()