mv compiler to compiler/

compiler/rustc_interface/src/proc_macro_decls.rs

@@ -0,0 +1,40 @@
+use rustc_hir as hir;
+use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
+use rustc_hir::itemlikevisit::ItemLikeVisitor;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::TyCtxt;
+use rustc_span::symbol::sym;
+
+pub fn find(tcx: TyCtxt<'_>) -> Option<DefId> {
+    tcx.proc_macro_decls_static(LOCAL_CRATE)
+}
+
+fn proc_macro_decls_static(tcx: TyCtxt<'_>, cnum: CrateNum) -> Option<DefId> {
+    assert_eq!(cnum, LOCAL_CRATE);
+
+    let mut finder = Finder { tcx, decls: None };
+    tcx.hir().krate().visit_all_item_likes(&mut finder);
+
+    finder.decls.map(|id| tcx.hir().local_def_id(id).to_def_id())
+}
+
+struct Finder<'tcx> {
+    tcx: TyCtxt<'tcx>,
+    decls: Option<hir::HirId>,
+}
+
+impl<'v> ItemLikeVisitor<'v> for Finder<'_> {
+    fn visit_item(&mut self, item: &hir::Item<'_>) {
+        if self.tcx.sess.contains_name(&item.attrs, sym::rustc_proc_macro_decls) {
+            self.decls = Some(item.hir_id);
+        }
+    }
+
+    fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem<'_>) {}
+
+    fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem<'_>) {}
+}
+
+pub(crate) fn provide(providers: &mut Providers) {
+    *providers = Providers { proc_macro_decls_static, ..*providers };
+}