Support placeholders for years in copyright

CHANGES.rst

@@ -53,6 +53,12 @@ Features added
   GMT (universal time) instead of local time for the date-time
   supplied to :confval:`html_last_updated_fmt`.
   Patch by Adam Turner.
+* #12910: Copyright entries now support the ``'%Y'`` placeholder
+  to substitute the current year.
+  This is helpful for reducing the reliance on Python modules
+  such as :py:mod:`time` or :py:mod:`datetime` in :file:`conf.py`.
+  See :ref:`the docs <config-copyright>` for further detail.
+  Patch by Adam Turner.
 
 Bugs fixed
 ----------

doc/conf.py

@@ -3,7 +3,6 @@
 
 import os
 import re
-import time
 from typing import TYPE_CHECKING
 
 from sphinx import __display_version__
@@ -27,7 +26,7 @@
 exclude_patterns = ['_build']
 
 project = 'Sphinx'
-copyright = f'2007-{time.strftime("%Y")}, the Sphinx developers'
+copyright = '2007-%Y, the Sphinx developers'
 release = version = __display_version__
 show_authors = True
 nitpicky = True

doc/usage/configuration.rst

@@ -114,6 +114,8 @@ Project information
 
       author = 'Joe Bloggs'
 
+.. _config-copyright:
+
 .. confval:: copyright
              project_copyright
    :type: :code-py:`str | Sequence[str]`
@@ -128,13 +130,24 @@ Project information
    * :code-py:`copyright = 'YYYY-YYYY, Author Name'`
    * :code-py:`copyright = 'YYYY-YYYY Author Name'`
 
+   If the string :code-py:`'%Y'` appears in a copyright line,
+   it will be replaced with the current four-digit year.
+   For example:
+
+   * :code-py:`copyright = '%Y'`
+   * :code-py:`copyright = '%Y, Author Name'`
+   * :code-py:`copyright = 'YYYY-%Y, Author Name'`
+
    .. versionadded:: 3.5
       The :code-py:`project_copyright` alias.
 
    .. versionchanged:: 7.1
       The value may now be a sequence of copyright statements in the above form,
       which will be displayed each to their own line.
 
+   .. versionchanged:: 8.1
+      Copyright statements support the :code-py:`'%Y'` placeholder.
+
 .. confval:: version
    :type: :code-py:`str`
    :default: :code-py:`''`
@@ -2528,6 +2541,7 @@ so the HTML options also apply where appropriate.
    :default: The value of **copyright**
 
    The copyright of the document.
+   See :confval:`copyright` for permitted formats.
 
 .. confval:: epub_identifier
    :type: :code-py:`str`

sphinx/config.py

@@ -619,6 +619,21 @@ def init_numfig_format(app: Sphinx, config: Config) -> None:
     config.numfig_format = numfig_format
 
 
+def evaluate_copyright_placeholders(_app: Sphinx, config: Config) -> None:
+    """Replace copyright year placeholders (%Y) with the current year."""
+    replace_yr = str(time.localtime().tm_year)
+    for k in ('copyright', 'epub_copyright'):
+        if k in config:
+            value: str | Sequence[str] = config[k]
+            if isinstance(value, str):
+                if '%Y' in value:
+                    config[k] = value.replace('%Y', replace_yr)
+            else:
+                if any('%Y' in line for line in value):
+                    items = (line.replace('%Y', replace_yr) for line in value)
+                    config[k] = type(value)(items)  # type: ignore[call-arg]
+
+
 def correct_copyright_year(_app: Sphinx, config: Config) -> None:
     """Correct values of copyright year that are not coherent with
     the SOURCE_DATE_EPOCH environment variable (if set)
@@ -775,6 +790,7 @@ def setup(app: Sphinx) -> ExtensionMetadata:
     app.connect('config-inited', convert_source_suffix, priority=800)
     app.connect('config-inited', convert_highlight_options, priority=800)
     app.connect('config-inited', init_numfig_format, priority=800)
+    app.connect('config-inited', evaluate_copyright_placeholders, priority=795)
     app.connect('config-inited', correct_copyright_year, priority=800)
     app.connect('config-inited', check_confval_types, priority=800)
     app.connect('config-inited', check_primary_domain, priority=800)

tests/test_config/test_correct_year.py → tests/test_config/test_copyright.py

@@ -4,7 +4,11 @@
 
 import pytest
 
-from sphinx.config import Config, correct_copyright_year
+from sphinx.config import (
+    Config,
+    correct_copyright_year,
+    evaluate_copyright_placeholders,
+)
 
 LT = time.localtime()
 LT_NEW = (2009, *LT[1:], LT.tm_zone, LT.tm_gmtoff)
@@ -106,6 +110,19 @@ def test_correct_year_single_no_author(expect_date):
         assert cfg.copyright == copyright_date
 
 
+def test_correct_year_placeholder(expect_date):
+    # test that copyright is substituted
+    copyright_date = '2006-%Y, Alice'
+    cfg = Config({'copyright': copyright_date}, {})
+    assert cfg.copyright == copyright_date
+    evaluate_copyright_placeholders(None, cfg)  # type: ignore[arg-type]
+    correct_copyright_year(None, cfg)  # type: ignore[arg-type]
+    if expect_date and expect_date <= LOCALTIME_2009.tm_year:
+        assert cfg.copyright == f'2006-{expect_date}, Alice'
+    else:
+        assert cfg.copyright == '2006-2009, Alice'
+
+
 def test_correct_year_multi_line(expect_date):
     # test that copyright is substituted
     copyright_dates = (
@@ -159,6 +176,47 @@ def test_correct_year_multi_line_all_formats(expect_date):
         assert cfg.copyright == copyright_dates
 
 
+def test_correct_year_multi_line_all_formats_placeholder(expect_date):
+    # test that copyright is substituted
+    copyright_dates = (
+        '%Y',
+        '%Y Alice',
+        '%Y, Bob',
+        '2006-%Y',
+        '2006-%Y Charlie',
+        '2006-%Y, David',
+        # other format codes are left as-is
+        '2006-%y, Eve',
+        '%Y-%m-%d %H:%M:S %z, Francis',
+    )
+    cfg = Config({'copyright': copyright_dates}, {})
+    assert cfg.copyright == copyright_dates
+    evaluate_copyright_placeholders(None, cfg)  # type: ignore[arg-type]
+    correct_copyright_year(None, cfg)  # type: ignore[arg-type]
+    if expect_date and expect_date <= LOCALTIME_2009.tm_year:
+        assert cfg.copyright == (
+            f'{expect_date}',
+            f'{expect_date} Alice',
+            f'{expect_date}, Bob',
+            f'2006-{expect_date}',
+            f'2006-{expect_date} Charlie',
+            f'2006-{expect_date}, David',
+            '2006-%y, Eve',
+            '2009-%m-%d %H:%M:S %z, Francis',
+        )
+    else:
+        assert cfg.copyright == (
+            '2009',
+            '2009 Alice',
+            '2009, Bob',
+            '2006-2009',
+            '2006-2009 Charlie',
+            '2006-2009, David',
+            '2006-%y, Eve',
+            '2009-%m-%d %H:%M:S %z, Francis',
+        )
+
+
 def test_correct_year_app(expect_date, tmp_path, make_app):
     # integration test
     copyright_date = '2006-2009, Alice'