mv compiler to compiler/

compiler/rustc_metadata/src/foreign_modules.rs

@@ -0,0 +1,34 @@
+use rustc_hir as hir;
+use rustc_hir::itemlikevisit::ItemLikeVisitor;
+use rustc_middle::middle::cstore::ForeignModule;
+use rustc_middle::ty::TyCtxt;
+
+crate fn collect(tcx: TyCtxt<'_>) -> Vec<ForeignModule> {
+    let mut collector = Collector { tcx, modules: Vec::new() };
+    tcx.hir().krate().visit_all_item_likes(&mut collector);
+    collector.modules
+}
+
+struct Collector<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    modules: Vec<ForeignModule>,
+}
+
+impl ItemLikeVisitor<'tcx> for Collector<'tcx> {
+    fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
+        let fm = match it.kind {
+            hir::ItemKind::ForeignMod(ref fm) => fm,
+            _ => return,
+        };
+
+        let foreign_items =
+            fm.items.iter().map(|it| self.tcx.hir().local_def_id(it.hir_id).to_def_id()).collect();
+        self.modules.push(ForeignModule {
+            foreign_items,
+            def_id: self.tcx.hir().local_def_id(it.hir_id).to_def_id(),
+        });
+    }
+
+    fn visit_trait_item(&mut self, _it: &'tcx hir::TraitItem<'tcx>) {}
+    fn visit_impl_item(&mut self, _it: &'tcx hir::ImplItem<'tcx>) {}
+}