Ensure Resolver::register_macros_for_all_crates only executes once

Author: estebank

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -180,6 +180,10 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     /// Add every proc macro accessible from the current crate to the `macro_map` so diagnostics can
     /// find them for suggestions.
     pub(crate) fn register_macros_for_all_crates(&mut self) {
+        if self.all_crate_macros_already_registered {
+            return;
+        }
+        self.all_crate_macros_already_registered = true;
         let def_ids = self.cstore().all_proc_macro_def_ids();
         for def_id in def_ids {
             self.get_macro_by_def_id(def_id);

compiler/rustc_resolve/src/lib.rs

@@ -1225,6 +1225,10 @@ pub struct Resolver<'ra, 'tcx> {
 
     mods_with_parse_errors: FxHashSet<DefId>,
 
+    /// Whether `Resolver::register_macros_for_all_crates` has been called once already, as we
+    /// don't need to run it more than once.
+    all_crate_macros_already_registered: bool,
+
     // Stores pre-expansion and pre-placeholder-fragment-insertion names for `impl Trait` types
     // that were encountered during resolution. These names are used to generate item names
     // for APITs, so we don't want to leak details of resolution into these names.
@@ -1602,6 +1606,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             all_macro_rules: Default::default(),
             delegation_fn_sigs: Default::default(),
             glob_delegation_invoc_ids: Default::default(),
+            all_crate_macros_already_registered: false,
             impl_unexpanded_invocations: Default::default(),
             impl_binding_keys: Default::default(),
             current_crate_outer_attr_insert_span,