fix: list an alias's data tree on its parent page

Data directory owners were picked among every profile, aliases included,
and an alias has no page: the 90 FreeIntv overlays linked to
emulators/freeintv_ts_overlay/, a 404. Only a profile with a page owns a
tree now, and a page lists the trees of the aliases that point at it.

scripts/generate_site.py

@@ -2029,11 +2029,37 @@ def data_directory_revisions(data_dir: Path = _REPO_ROOT / "data") -> dict[str,
     return json.loads(path.read_text(encoding="utf-8"))
 
 
+def page_data_directories(name: str, profiles: dict) -> list[dict]:
+    """The data directories an emulator page lists.
+
+    Its own, then those of the aliases that point at it: an alias has no
+    page, and the 90 FreeIntv overlays its profile declares were linked to
+    emulators/freeintv_ts_overlay/, a page that does not exist.
+    """
+    trees = [t for t in profiles[name].get("data_directories") or [] if isinstance(t, dict)]
+    refs = {str(t.get("ref", "")) for t in trees}
+    for alias in sorted(profiles):
+        profile = profiles[alias]
+        if profile.get("type") != "alias" or profile.get("alias_of") != name:
+            continue
+        for tree in profile.get("data_directories") or []:
+            ref = str(tree.get("ref", ""))
+            if isinstance(tree, dict) and ref not in refs:
+                refs.add(ref)
+                trees.append(tree)
+    return trees
+
+
 def _data_member_owners(profiles: dict) -> dict[str, str]:
-    """The emulator page that lists each data directory, the first by name."""
+    """The emulator page that lists each data directory, the first by name.
+
+    Only a profile that has a page can own one.
+    """
     owners: dict[str, str] = {}
     for name in sorted(profiles):
-        for tree in profiles[name].get("data_directories") or []:
+        if profiles[name].get("type") in ("alias", "test"):
+            continue
+        for tree in page_data_directories(name, profiles):
             owners.setdefault(str(tree.get("ref", "")), name)
     return owners
 
@@ -3285,7 +3311,9 @@ def generate_emulator_page(
     consumers: FileConsumers | None = None,
     data_names: set[str] | None = None,
     data_registry: dict | None = None,
+    data_dirs: list[dict] | None = None,
 ) -> str:
+    """One emulator's page. ``data_dirs`` defaults to the profile's own."""
     if profile.get("type") == "alias":
         parent = profile.get("alias_of", profile.get("bios_identical_to", "unknown"))
         return (
@@ -3323,7 +3351,8 @@ def generate_emulator_page(
         str(notes_raw).strip() if notes_raw and not isinstance(notes_raw, dict) else ""
     )
     exclusion = profile.get("exclusion_note", "")
-    data_dirs = profile.get("data_directories", [])
+    if data_dirs is None:
+        data_dirs = profile.get("data_directories", [])
 
     lines = [
         f"# {emu_name}",
@@ -5019,7 +5048,8 @@ def _generate(args: argparse.Namespace) -> None:
             ) + "\n",
         )
         page = generate_emulator_page(
-            name, profile, db, consumers, suppl_names, data_registry
+            name, profile, db, consumers, suppl_names, data_registry,
+            data_dirs=page_data_directories(name, profiles),
         )
         PAGE_DATA[f"emulators/{name}.md"] = emulator_structured_data(profile)
         write_if_changed(str(docs / "emulators" / f"{name}.md"), page)

tests/test_site_render.py

@@ -241,5 +241,33 @@ class DirectoryMembersNameTheirEmulator(unittest.TestCase):
                                r"\[`bios/Bungie/Marathon/Plugins/`\]\(\.\./systems/bungie\.md#")
 
 
+class AnAliasTreeIsListedOnItsParentsPage(unittest.TestCase):
+    """The 90 FreeIntv overlays were linked to the page of the alias that
+    declares them, which is never generated: every permalink was a 404."""
+
+    PROFILES = {
+        "freeintv": {"type": "libretro"},
+        "freeintv_ts_overlay": {
+            "type": "alias", "alias_of": "freeintv",
+            "data_directories": [{"ref": "freeintv-overlays",
+                                  "destination": "freeintv_overlays"}],
+        },
+    }
+
+    def test_the_permalink_goes_to_a_page_that_exists(self):
+        import generate_site
+
+        members = {"freeintv-overlays": {"a.png": {"sha1": "02" * 20}}}
+        items = generate_site.file_location_items({"files": {}}, self.PROFILES, members)
+        self.assertEqual(items, [{"sha1": "02" * 20,
+                                  "url": "emulators/freeintv/#sha1-020202020202"}])
+
+    def test_the_parent_page_lists_the_tree(self):
+        import generate_site
+
+        trees = generate_site.page_data_directories("freeintv", self.PROFILES)
+        self.assertEqual([t["ref"] for t in trees], ["freeintv-overlays"])
+
+
 if __name__ == "__main__":
     unittest.main()