1 files changed, 38 insertions, 0 deletions
diff --git a/src/librustdoc/json/import_finder.rs b/src/librustdoc/json/import_finder.rs
new file mode 100644
index 000000000..c5c687df7
--- /dev/null
+++ b/src/librustdoc/json/import_finder.rs
@@ -0,0 +1,38 @@
+use rustc_data_structures::fx::FxHashSet;
+use rustc_hir::def_id::DefId;
+
+use crate::{
+    clean::{self, Import, ImportSource, Item},
+    fold::DocFolder,
+};
+
+/// Get the id's of all items that are `pub use`d in the crate.
+///
+/// We need this to know if a stripped module is `pub use mod::*`, to decide
+/// if it needs to be kept in the index, despite being stripped.
+///
+/// See [#100973](https://github.com/rust-lang/rust/issues/100973) and
+/// [#101103](https://github.com/rust-lang/rust/issues/101103) for times when
+/// this information is needed.
+pub(crate) fn get_imports(krate: clean::Crate) -> (clean::Crate, FxHashSet<DefId>) {
+    let mut finder = ImportFinder { imported: FxHashSet::default() };
+    let krate = finder.fold_crate(krate);
+    (krate, finder.imported)
+}
+
+struct ImportFinder {
+    imported: FxHashSet<DefId>,
+}
+
+impl DocFolder for ImportFinder {
+    fn fold_item(&mut self, i: Item) -> Option<Item> {
+        match *i.kind {
+            clean::ImportItem(Import { source: ImportSource { did: Some(did), .. }, .. }) => {
+                self.imported.insert(did);
+                Some(i)
+            }
+
+            _ => Some(self.fold_item_recur(i)),
+        }
+    }
+}