Stop passing in values that one can also get from the tcx lazily

compiler/rustc_interface/src/passes.rs

@@ -571,13 +571,7 @@ fn resolver_for_lowering<'tcx>(
 ) -> &'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)> {
     let arenas = Resolver::arenas();
     let krate = tcx.crate_for_resolver(()).steal();
-    let mut resolver = Resolver::new(
-        tcx,
-        &krate,
-        tcx.crate_name(LOCAL_CRATE),
-        tcx.metadata_loader(()).steal(),
-        &arenas,
-    );
+    let mut resolver = Resolver::new(tcx, &krate, &arenas);
     let krate = configure_and_expand(tcx, krate, &mut resolver);
 
     // Make sure we don't mutate the cstore from here on.

compiler/rustc_metadata/src/creader.rs

@@ -15,8 +15,8 @@ use rustc_hir::definitions::Definitions;
 use rustc_index::vec::IndexVec;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{self, CrateType, ExternLocation};
+use rustc_session::cstore::ExternCrateSource;
 use rustc_session::cstore::{CrateDepKind, CrateSource, ExternCrate};
-use rustc_session::cstore::{ExternCrateSource, MetadataLoaderDyn};
 use rustc_session::lint;
 use rustc_session::output::validate_crate_name;
 use rustc_session::search_paths::PathKind;
@@ -60,16 +60,22 @@ impl std::fmt::Debug for CStore {
     }
 }
 
-pub struct CrateLoader<'a> {
+pub struct CrateLoader<'a, 'tcx: 'a> {
     // Immutable configuration.
-    sess: &'a Session,
-    metadata_loader: &'a MetadataLoaderDyn,
-    local_crate_name: Symbol,
+    tcx: TyCtxt<'tcx>,
     // Mutable output.
     cstore: &'a mut CStore,
     used_extern_options: &'a mut FxHashSet<Symbol>,
 }
 
+impl<'a, 'tcx> std::ops::Deref for CrateLoader<'a, 'tcx> {
+    type Target = TyCtxt<'tcx>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.tcx
+    }
+}
+
 pub enum LoadedMacro {
     MacroDef(ast::Item, Edition),
     ProcMacro(SyntaxExtension),
@@ -254,15 +260,13 @@ impl CStore {
     }
 }
 
-impl<'a> CrateLoader<'a> {
+impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
     pub fn new(
-        sess: &'a Session,
-        metadata_loader: &'a MetadataLoaderDyn,
-        local_crate_name: Symbol,
+        tcx: TyCtxt<'tcx>,
         cstore: &'a mut CStore,
         used_extern_options: &'a mut FxHashSet<Symbol>,
     ) -> Self {
-        CrateLoader { sess, metadata_loader, local_crate_name, cstore, used_extern_options }
+        CrateLoader { tcx, cstore, used_extern_options }
     }
     pub fn cstore(&self) -> &CStore {
         &self.cstore
@@ -553,9 +557,10 @@ impl<'a> CrateLoader<'a> {
             (LoadResult::Previous(cnum), None)
         } else {
             info!("falling back to a load");
+            let metadata_loader = self.tcx.metadata_loader(()).borrow();
             let mut locator = CrateLocator::new(
                 self.sess,
-                &*self.metadata_loader,
+                &**metadata_loader,
                 name,
                 hash,
                 extra_filename,
@@ -960,7 +965,7 @@ impl<'a> CrateLoader<'a> {
                     &format!(
                         "external crate `{}` unused in `{}`: remove the dependency or add `use {} as _;`",
                         name,
-                        self.local_crate_name,
+                        self.tcx.crate_name(LOCAL_CRATE),
                         name),
                 );
         }

compiler/rustc_resolve/src/lib.rs

@@ -44,7 +44,7 @@ use rustc_middle::span_bug;
 use rustc_middle::ty::{self, DefIdTree, MainDefinition, RegisteredTools, TyCtxt};
 use rustc_middle::ty::{ResolverGlobalCtxt, ResolverOutputs};
 use rustc_query_system::ich::StableHashingContext;
-use rustc_session::cstore::{CrateStore, MetadataLoaderDyn, Untracked};
+use rustc_session::cstore::{CrateStore, Untracked};
 use rustc_session::lint::LintBuffer;
 use rustc_span::hygiene::{ExpnId, LocalExpnId, MacroKind, SyntaxContext, Transparency};
 use rustc_span::source_map::Spanned;
@@ -955,8 +955,6 @@ pub struct Resolver<'a, 'tcx> {
     arenas: &'a ResolverArenas<'a>,
     dummy_binding: &'a NameBinding<'a>,
 
-    local_crate_name: Symbol,
-    metadata_loader: Box<MetadataLoaderDyn>,
     used_extern_options: FxHashSet<Symbol>,
     macro_names: FxHashSet<Ident>,
     builtin_macros: FxHashMap<Symbol, BuiltinMacroState>,
@@ -1203,8 +1201,6 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
     pub fn new(
         tcx: TyCtxt<'tcx>,
         krate: &Crate,
-        crate_name: Symbol,
-        metadata_loader: Box<MetadataLoaderDyn>,
         arenas: &'a ResolverArenas<'a>,
     ) -> Resolver<'a, 'tcx> {
         let root_def_id = CRATE_DEF_ID.to_def_id();
@@ -1312,8 +1308,6 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                 vis: ty::Visibility::Public,
             }),
 
-            metadata_loader,
-            local_crate_name: crate_name,
             used_extern_options: Default::default(),
             macro_names: FxHashSet::default(),
             builtin_macros: Default::default(),
@@ -1464,14 +1458,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         StableHashingContext::new(self.tcx.sess, self.tcx.untracked())
     }
 
-    fn crate_loader<T>(&mut self, f: impl FnOnce(&mut CrateLoader<'_>) -> T) -> T {
-        f(&mut CrateLoader::new(
-            &self.tcx.sess,
-            &*self.metadata_loader,
-            self.local_crate_name,
-            &mut *self.tcx.untracked().cstore.write().untracked_as_any().downcast_mut().unwrap(),
-            &mut self.used_extern_options,
-        ))
+    fn crate_loader<T>(&mut self, f: impl FnOnce(&mut CrateLoader<'_, '_>) -> T) -> T {
+        let mut cstore = self.tcx.untracked().cstore.write();
+        let cstore = cstore.untracked_as_any().downcast_mut().unwrap();
+        f(&mut CrateLoader::new(self.tcx, &mut *cstore, &mut self.used_extern_options))
     }
 
     fn cstore(&self) -> MappedReadGuard<'_, CStore> {