make subst_mir take EarlyBinder

Author: kylematsuda

compiler/rustc_middle/src/ty/instance.rs

@@ -578,14 +578,15 @@ impl<'tcx> Instance<'tcx> {
         self.def.has_polymorphic_mir_body().then_some(self.substs)
     }
 
-    pub fn subst_mir<T>(&self, tcx: TyCtxt<'tcx>, v: &T) -> T
+    pub fn subst_mir<T>(&self, tcx: TyCtxt<'tcx>, v: EarlyBinder<&T>) -> T
     where
         T: TypeFoldable<TyCtxt<'tcx>> + Copy,
     {
+        let v = v.map_bound(|v| *v);
         if let Some(substs) = self.substs_for_mir_body() {
-            EarlyBinder(*v).subst(tcx, substs)
+            v.subst(tcx, substs)
         } else {
-            *v
+            v.subst_identity()
         }
     }
 

compiler/rustc_mir_transform/src/inline.rs

@@ -444,7 +444,9 @@ impl<'tcx> Inliner<'tcx> {
                 work_list.push(target);
 
                 // If the place doesn't actually need dropping, treat it like a regular goto.
-                let ty = callsite.callee.subst_mir(self.tcx, &place.ty(callee_body, tcx).ty);
+                let ty = callsite
+                    .callee
+                    .subst_mir(self.tcx, ty::EarlyBinder(&place.ty(callee_body, tcx).ty));
                 if ty.needs_drop(tcx, self.param_env) && let UnwindAction::Cleanup(unwind) = unwind {
                         work_list.push(unwind);
                     }
@@ -788,7 +790,9 @@ impl<'tcx> Visitor<'tcx> for CostChecker<'_, 'tcx> {
         match terminator.kind {
             TerminatorKind::Drop { ref place, unwind, .. } => {
                 // If the place doesn't actually need dropping, treat it like a regular goto.
-                let ty = self.instance.subst_mir(tcx, &place.ty(self.callee_body, tcx).ty);
+                let ty = self
+                    .instance
+                    .subst_mir(tcx, ty::EarlyBinder(&place.ty(self.callee_body, tcx).ty));
                 if ty.needs_drop(tcx, self.param_env) {
                     self.cost += CALL_PENALTY;
                     if let UnwindAction::Cleanup(_) = unwind {
@@ -799,7 +803,7 @@ impl<'tcx> Visitor<'tcx> for CostChecker<'_, 'tcx> {
                 }
             }
             TerminatorKind::Call { func: Operand::Constant(ref f), unwind, .. } => {
-                let fn_ty = self.instance.subst_mir(tcx, &f.literal.ty());
+                let fn_ty = self.instance.subst_mir(tcx, ty::EarlyBinder(&f.literal.ty()));
                 self.cost += if let ty::FnDef(def_id, _) = *fn_ty.kind() && tcx.is_intrinsic(def_id) {
                     // Don't give intrinsics the extra penalty for calls
                     INSTR_COST