4 files changed, 21 insertions, 3 deletions
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index cbb030958c6..4f9b362e237 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -2133,6 +2133,20 @@ impl CheckAttrVisitor<'_> {
                     );
                 }
             }
+        } else {
+            // special case when `#[macro_export]` is applied to a macro 2.0
+            let (macro_definition, _) =
+                self.tcx.hir().find(hir_id).unwrap().expect_item().expect_macro();
+            let is_decl_macro = !macro_definition.macro_rules;
+
+            if is_decl_macro {
+                self.tcx.emit_spanned_lint(
+                    UNUSED_ATTRIBUTES,
+                    hir_id,
+                    attr.span,
+                    errors::MacroExport::OnDeclMacro,
+                );
+            }
         }
     }
 
diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs
index fbe6fc3bee4..07b437f463f 100644
--- a/compiler/rustc_passes/src/dead.rs
+++ b/compiler/rustc_passes/src/dead.rs
@@ -87,7 +87,7 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
 
     fn handle_res(&mut self, res: Res) {
         match res {
-            Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::TyAlias, def_id) => {
+            Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::TyAlias { .. }, def_id) => {
                 self.check_def_id(def_id);
             }
             _ if self.in_pat => {}
@@ -861,7 +861,7 @@ impl<'tcx> DeadVisitor<'tcx> {
             | DefKind::Fn
             | DefKind::Static(_)
             | DefKind::Const
-            | DefKind::TyAlias
+            | DefKind::TyAlias { .. }
             | DefKind::Enum
             | DefKind::Union
             | DefKind::ForeignTy => self.warn_dead_code(def_id, "used"),
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index 4f5514372d1..683717344ce 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -690,6 +690,10 @@ pub enum MacroExport {
     #[diag(passes_macro_export)]
     Normal,
 
+    #[diag(passes_macro_export_on_decl_macro)]
+    #[note]
+    OnDeclMacro,
+
     #[diag(passes_invalid_macro_export_arguments)]
     UnknownItem { name: Symbol },
 
diff --git a/compiler/rustc_passes/src/layout_test.rs b/compiler/rustc_passes/src/layout_test.rs
index 794dbda3688..0463ee2914b 100644
--- a/compiler/rustc_passes/src/layout_test.rs
+++ b/compiler/rustc_passes/src/layout_test.rs
@@ -16,7 +16,7 @@ pub fn test_layout(tcx: TyCtxt<'_>) {
         for id in tcx.hir().items() {
             if matches!(
                 tcx.def_kind(id.owner_id),
-                DefKind::TyAlias | DefKind::Enum | DefKind::Struct | DefKind::Union
+                DefKind::TyAlias { .. } | DefKind::Enum | DefKind::Struct | DefKind::Union
             ) {
                 for attr in tcx.get_attrs(id.owner_id, sym::rustc_layout) {
                     dump_layout_of(tcx, id.owner_id.def_id, attr);