[3.11] pythongh-121277: Allow .. versionadded:: next in docs (pythonGH-121278) (python#124718)

Make `versionchanged:: next`` expand to current (unreleased) version.

When a new CPython release is cut, the release manager will replace
all such occurences of "next" with the just-released version.
(See the issue for release-tools and devguide PRs.)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
(cherry picked from commit 7d24ea9)

pythongh-121277: Raise nice error on `next` as second argument to deprecated-removed (pythonGH-124623)

(cherry-picked from e349f73)

Author: encukou

Doc/tools/extensions/pyspecific.py

@@ -414,7 +414,22 @@ def run(self):
         return PyMethod.run(self)
 
 
-# Support for documenting version of removal in deprecations
+# Support for documenting version of changes, additions, deprecations
+
+def expand_version_arg(argument, release):
+    """Expand "next" to the current version"""
+    if argument == 'next':
+        return sphinx_gettext('{} (unreleased)').format(release)
+    return argument
+
+
+class PyVersionChange(VersionChange):
+    def run(self):
+        # Replace the 'next' special token with the current development version
+        self.arguments[0] = expand_version_arg(self.arguments[0],
+                                               self.config.release)
+        return super().run()
+
 
 class DeprecatedRemoved(Directive):
     has_content = True
@@ -430,7 +445,13 @@ def run(self):
         node = addnodes.versionmodified()
         node.document = self.state.document
         node['type'] = 'deprecated-removed'
-        version = (self.arguments[0], self.arguments[1])
+        version = (
+            expand_version_arg(self.arguments[0], self.config.release),
+            self.arguments[1],
+        )
+        if version[1] == 'next':
+            raise ValueError(
+                'deprecated-removed:: second argument cannot be `next`')
         node['version'] = version
         env = self.state.document.settings.env
         current_version = tuple(int(e) for e in env.config.version.split('.'))
@@ -713,6 +734,10 @@ def setup(app):
     app.add_directive('availability', Availability)
     app.add_directive('audit-event', AuditEvent)
     app.add_directive('audit-event-table', AuditEventListDirective)
+    app.add_directive('versionadded', PyVersionChange, override=True)
+    app.add_directive('versionchanged', PyVersionChange, override=True)
+    app.add_directive('versionremoved', PyVersionChange, override=True)
+    app.add_directive('deprecated', PyVersionChange, override=True)
     app.add_directive('deprecated-removed', DeprecatedRemoved)
     app.add_builder(PydocTopicsBuilder)
     app.add_builder(suspicious.CheckSuspiciousMarkupBuilder)

Misc/NEWS.d/next/Documentation/2024-07-19-12-22-48.gh-issue-121277.wF_zKd.rst

@@ -0,0 +1,2 @@
+Writers of CPython's documentation can now use ``next`` as the version for
+the ``versionchanged``, ``versionadded``, ``deprecated`` directives.