rustc_interface: Add a new query `pre_configure`

It partially expands crate attributes before the main expansion pass (without modifying the crate), and the produced preliminary crate attribute list is used for querying a few attributes that are required very early.

Crate-level cfg attributes are then expanded normally during the main expansion pass, like attributes on any other nodes.

2 files changed, 8 insertions, 7 deletions

diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index a0b9188c315..bcc83c5b4ce 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -1180,7 +1180,8 @@ impl<'tcx> Resolver<'_, 'tcx> {
 impl<'a, 'tcx> Resolver<'a, 'tcx> {
     pub fn new(
         tcx: TyCtxt<'tcx>,
-        krate: &Crate,
+        attrs: &[ast::Attribute],
+        crate_span: Span,
         arenas: &'a ResolverArenas<'a>,
     ) -> Resolver<'a, 'tcx> {
         let root_def_id = CRATE_DEF_ID.to_def_id();
@@ -1189,8 +1190,8 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             None,
             ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty),
             ExpnId::root(),
-            krate.spans.inner_span,
-            attr::contains_name(&krate.attrs, sym::no_implicit_prelude),
+            crate_span,
+            attr::contains_name(attrs, sym::no_implicit_prelude),
             &mut module_map,
         );
         let empty_module = arenas.new_module(
@@ -1222,9 +1223,9 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             .map(|(name, _)| (Ident::from_str(name), Default::default()))
             .collect();
 
-        if !attr::contains_name(&krate.attrs, sym::no_core) {
+        if !attr::contains_name(attrs, sym::no_core) {
             extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
-            if !attr::contains_name(&krate.attrs, sym::no_std) {
+            if !attr::contains_name(attrs, sym::no_std) {
                 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
             }
         }
diff --git a/compiler/rustc_resolve/src/macros.rs b/compiler/rustc_resolve/src/macros.rs
index c540682d8db..48707d37a10 100644
--- a/compiler/rustc_resolve/src/macros.rs
+++ b/compiler/rustc_resolve/src/macros.rs
@@ -112,8 +112,8 @@ fn fast_print_path(path: &ast::Path) -> Symbol {
 
 pub(crate) fn registered_tools(tcx: TyCtxt<'_>, (): ()) -> RegisteredTools {
     let mut registered_tools = RegisteredTools::default();
-    let krate = tcx.crate_for_resolver(()).borrow();
-    for attr in attr::filter_by_name(&krate.attrs, sym::register_tool) {
+    let (_, pre_configured_attrs) = &*tcx.crate_for_resolver(()).borrow();
+    for attr in attr::filter_by_name(pre_configured_attrs, sym::register_tool) {
         for nested_meta in attr.meta_item_list().unwrap_or_default() {
             match nested_meta.ident() {
                 Some(ident) => {