Auto merge of rust-lang#65087 - Centril:rollup-skxq0zr, r=Centril

Rollup of 5 pull requests

Successful merges:

 - rust-lang#64749 (Fix most remaining Polonius test differences)
 - rust-lang#64817 (Replace ClosureSubsts with SubstsRef)
 - rust-lang#64874 (Simplify ExprUseVisitor)
 - rust-lang#65026 (metadata: Some crate loading cleanup)
 - rust-lang#65073 (Remove `borrowck_graphviz_postflow` from test)

Failed merges:

r? @ghost

src/librustc/infer/error_reporting/need_type_info.rs

@@ -220,7 +220,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
 
         let ty_msg = match local_visitor.found_ty {
             Some(ty::TyS { kind: ty::Closure(def_id, substs), .. }) => {
-                let fn_sig = substs.closure_sig(*def_id, self.tcx);
+                let fn_sig = substs.as_closure().sig(*def_id, self.tcx);
                 let args = closure_args(&fn_sig);
                 let ret = fn_sig.output().skip_binder().to_string();
                 format!(" for the closure `fn({}) -> {}`", args, ret)
@@ -255,7 +255,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
 
         let suffix = match local_visitor.found_ty {
             Some(ty::TyS { kind: ty::Closure(def_id, substs), .. }) => {
-                let fn_sig = substs.closure_sig(*def_id, self.tcx);
+                let fn_sig = substs.as_closure().sig(*def_id, self.tcx);
                 let ret = fn_sig.output().skip_binder().to_string();
 
                 if let Some(ExprKind::Closure(_, decl, body_id, ..)) = local_visitor.found_closure {

src/librustc/infer/mod.rs

@@ -1504,9 +1504,9 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     pub fn closure_kind(
         &self,
         closure_def_id: DefId,
-        closure_substs: ty::ClosureSubsts<'tcx>,
+        closure_substs: SubstsRef<'tcx>,
     ) -> Option<ty::ClosureKind> {
-        let closure_kind_ty = closure_substs.closure_kind_ty(closure_def_id, self.tcx);
+        let closure_kind_ty = closure_substs.as_closure().kind_ty(closure_def_id, self.tcx);
         let closure_kind_ty = self.shallow_resolve(closure_kind_ty);
         closure_kind_ty.to_opt_closure_kind()
     }
@@ -1518,9 +1518,9 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     pub fn closure_sig(
         &self,
         def_id: DefId,
-        substs: ty::ClosureSubsts<'tcx>,
+        substs: SubstsRef<'tcx>,
     ) -> ty::PolyFnSig<'tcx> {
-        let closure_sig_ty = substs.closure_sig_ty(def_id, self.tcx);
+        let closure_sig_ty = substs.as_closure().sig_ty(def_id, self.tcx);
         let closure_sig_ty = self.shallow_resolve(closure_sig_ty);
         closure_sig_ty.fn_sig(self.tcx)
     }

src/librustc/infer/opaque_types/mod.rs

@@ -722,11 +722,11 @@ where
             ty::Closure(def_id, ref substs) => {
                 // Skip lifetime parameters of the enclosing item(s)
 
-                for upvar_ty in substs.upvar_tys(def_id, self.tcx) {
+                for upvar_ty in substs.as_closure().upvar_tys(def_id, self.tcx) {
                     upvar_ty.visit_with(self);
                 }
 
-                substs.closure_sig_ty(def_id, self.tcx).visit_with(self);
+                substs.as_closure().sig_ty(def_id, self.tcx).visit_with(self);
             }
 
             ty::Generator(def_id, ref substs, _) => {
@@ -886,7 +886,7 @@ impl TypeFolder<'tcx> for ReverseMapper<'tcx> {
 
                 let generics = self.tcx.generics_of(def_id);
                 let substs =
-                    self.tcx.mk_substs(substs.substs.iter().enumerate().map(|(index, &kind)| {
+                    self.tcx.mk_substs(substs.iter().enumerate().map(|(index, &kind)| {
                         if index < generics.parent_count {
                             // Accommodate missing regions in the parent kinds...
                             self.fold_kind_mapping_missing_regions_to_empty(kind)
@@ -896,7 +896,7 @@ impl TypeFolder<'tcx> for ReverseMapper<'tcx> {
                         }
                     }));
 
-                self.tcx.mk_closure(def_id, ty::ClosureSubsts { substs })
+                self.tcx.mk_closure(def_id, substs)
             }
 
             ty::Generator(def_id, substs, movability) => {

src/librustc/middle/cstore.rs

@@ -148,9 +148,7 @@ pub enum ExternCrateSource {
         /// such ids
         DefId,
     ),
-    // Crate is loaded by `use`.
-    Use,
-    /// Crate is implicitly loaded by an absolute path.
+    /// Crate is implicitly loaded by a path resolving through extern prelude.
     Path,
 }