[singlehtml] Append docname to refid and ids

Use doc path to make ids unique with format ``/docname/#id``.
Compensates for the loss of the pathname in the href.
This will break existing hyperlinks to `singlehtml` HTML documents since
it alters the format

Author: gastmaier

sphinx/builders/singlehtml.py

@@ -42,7 +42,7 @@ def get_outdated_docs(self) -> str | list[str]:  # type: ignore[override]
     def get_target_uri(self, docname: str, typ: str | None = None) -> str:
         if docname in self.env.all_docs:
             # all references are on the same page...
-            return '#document-' + docname
+            return '#/' + docname + '/'
         else:
             # chances are this is a html_additional_page
             return docname + self.out_suffix
@@ -88,13 +88,28 @@ def _get_local_toctree(
         )
         return self.render_partial(toctree)['fragment']
 
+    def ensure_fully_qualified_refids(self, tree: nodes.document) -> None:
+        """Append docname to refids and ids using format
+        /docname/#id. Compensates for loss of the pathname section
+        of the href, that ensures uniqueness in the html builder.
+        """
+        for node in tree.findall(nodes.Element):
+            assert node.document is not None
+            if 'refid' in node or 'ids' in node:
+                docname = self.env.path2doc(node.document['source'])
+            if 'refid' in node:
+                node['refid'] = f'/{docname}/#{node["refid"]}'
+            if 'ids' in node:
+                node['ids'] = [f'/{docname}/#{id}' for id in node['ids']]
+
     def assemble_doctree(self) -> nodes.document:
         master = self.config.root_doc
         tree = self.env.get_doctree(master)
         logger.info(darkgreen(master))
         tree = inline_all_toctrees(self, set(), master, tree, darkgreen, [master])
         tree['docname'] = master
         self.env.resolve_references(tree, master, self)
+        self.ensure_fully_qualified_refids(tree)
         return tree
 
     def assemble_toc_secnumbers(self) -> dict[str, dict[str, tuple[int, ...]]]:

sphinx/writers/html5.py

@@ -67,7 +67,7 @@ def __init__(self, document: nodes.document, builder: Builder) -> None:
     def visit_start_of_file(self, node: Element) -> None:
         # only occurs in the single-file builder
         self.docnames.append(node['docname'])
-        self.body.append('<span id="document-%s"></span>' % node['docname'])
+        self.body.append('<span id="/%s/"></span>' % node['docname'])
 
     def depart_start_of_file(self, node: Element) -> None:
         self.docnames.pop()