pythongh-108514: Add config & transform to hide old versionmodified i…

…n docs

Doc/conf.py

@@ -68,6 +68,9 @@
 # Minimum version of sphinx required
 needs_sphinx = '3.2'
 
+# Hide versionadded and versionchanged in the output older than this version
+min_version_show_changes = '3.6'
+
 # Ignore any .rst files in the includes/ directory;
 # they're embedded in pages but not rendered individually.
 # Ignore any .rst files in the venv/ directory.
@@ -76,6 +79,7 @@
 if venvdir is not None:
     exclude_patterns.append(venvdir + '/*')
 
+
 nitpick_ignore = [
     # Standard C functions
     ('c:func', 'calloc'),

Doc/tools/extensions/pyspecific.py

@@ -695,7 +695,21 @@ def patch_pairindextypes(app, _env) -> None:
         pairindextypes.clear()
 
 
+def hide_old_versionmodified(app, doctree, fromdocname):
+    """Remove versionmodified nodes (added/changed) older than the minimum."""
+    min_version = app.config.min_version_show_changes
+    if not min_version:
+        return
+    min_version = [int(part) for part in min_version.split(".")]
+    for node in list(doctree.findall(addnodes.versionmodified)):
+        if node['type'] in ('versionadded', 'versionchanged'):
+            node_version = [int(part) for part in node['version'].split(".")]
+            if node_version < min_version:
+                node.parent.remove(node)
+
+
 def setup(app):
+    app.add_config_value('min_version_show_changes', '', 'html')
     app.add_role('issue', issue_role)
     app.add_role('gh', gh_issue_role)
     app.add_role('source', source_role)
@@ -717,6 +731,7 @@ def setup(app):
     app.add_directive('miscnews', MiscNews)
     app.connect('env-check-consistency', patch_pairindextypes)
     app.connect('doctree-resolved', process_audit_events)
+    app.connect('doctree-resolved', hide_old_versionmodified)
     app.connect('env-merge-info', audit_events_merge)
     app.connect('env-purge-doc', audit_events_purge)
     return {'version': '1.0', 'parallel_read_safe': True}