Don't hide introspection metadata

Fixes #622

src/doc.rs

@@ -263,14 +263,20 @@ impl Frame {
 
     /// Attach metadata from an iterator.
     pub fn meta_iter(&mut self, iter: impl IntoIterator<Item = Meta>) {
+        let mut hide = false;
         for meta in iter {
             if matches!(meta, Meta::Hide) {
-                self.clear();
+                hide = true;
-                break;
+            } else {
-            }
                 self.prepend(Point::zero(), FrameItem::Meta(meta, self.size));
             }
         }
+        if hide {
+            Arc::make_mut(&mut self.items).retain(|(_, item)| {
+                matches!(item, FrameItem::Group(_) | FrameItem::Meta(Meta::Elem(_), _))
+            });
+        }
+    }
 
     /// Add a background fill.
     pub fn fill(&mut self, fill: Paint) {

tests/typ/bugs/hide-meta.typ

@@ -0,0 +1,24 @@
+// Test that metadata of hidden stuff stays available.
+
+---
+#set cite(style: "chicago-notes")
+
+A pirate. @arrgh \
+#set text(2pt)
+#hide[
+  A @arrgh pirate.
+  #bibliography("/works.bib")
+]
+
+---
+#set text(8pt)
+#outline()
+#set text(2pt)
+#hide(block(grid(
+  [= A],
+  [= B],
+  block(grid(
+    [= C],
+    [= D],
+  ))
+)))