minor

src/librustc/ty/context.rs

@@ -40,7 +40,7 @@ use crate::ty::steal::Steal;
 use crate::ty::subst::{UserSubsts, UnpackedKind};
 use crate::ty::{BoundVar, BindingMode};
 use crate::ty::CanonicalPolyFnSig;
-use crate::util::nodemap::{DefIdMap, DefIdSet, ItemLocalMap};
+use crate::util::nodemap::{DefIdMap, DefIdSet, ItemLocalMap, ItemLocalSet};
 use crate::util::nodemap::{FxHashMap, FxHashSet};
 use errors::DiagnosticBuilder;
 use rustc_data_structures::interner::HashInterner;
@@ -409,9 +409,7 @@ pub struct TypeckTables<'tcx> {
     /// MIR construction and hence is not serialized to metadata.
     fru_field_types: ItemLocalMap<Vec<Ty<'tcx>>>,
 
-    /// Maps a cast expression to its kind. This is keyed on the
-    /// *from* expression of the cast, not the cast itself.
-    cast_kinds: ItemLocalMap<ty::cast::CastKind>,
+    coercion_casts: ItemLocalSet,
 
     /// Set of trait imports actually used in the method resolution.
     /// This is used for warning unused imports. During type
@@ -456,7 +454,7 @@ impl<'tcx> TypeckTables<'tcx> {
             closure_kind_origins: Default::default(),
             liberated_fn_sigs: Default::default(),
             fru_field_types: Default::default(),
-            cast_kinds: Default::default(),
+            coercion_casts: Default::default(),
             used_trait_imports: Lrc::new(Default::default()),
             tainted_by_errors: false,
             free_region_map: Default::default(),
@@ -718,19 +716,17 @@ impl<'tcx> TypeckTables<'tcx> {
         }
     }
 
-    pub fn cast_kinds(&self) -> LocalTableInContext<'_, ty::cast::CastKind> {
-        LocalTableInContext {
-            local_id_root: self.local_id_root,
-            data: &self.cast_kinds
+    pub fn is_coercion_cast(&self, hir_id: &hir::HirId) -> bool {
+        if self.coercion_casts.contains(&hir_id.local_id) {
+            return true
         }
+        false
     }
 
-    pub fn cast_kinds_mut(&mut self) -> LocalTableInContextMut<'_, ty::cast::CastKind> {
-        LocalTableInContextMut {
-            local_id_root: self.local_id_root,
-            data: &mut self.cast_kinds
-        }
+    pub fn set_coercion_cast(&mut self, hir_id: &hir::HirId) -> () {
+        self.coercion_casts.insert(hir_id.local_id);
     }
+
 }
 
 impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for TypeckTables<'gcx> {
@@ -753,7 +749,7 @@ impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for TypeckTables<'gcx> {
             ref liberated_fn_sigs,
             ref fru_field_types,
 
-            ref cast_kinds,
+            ref coercion_casts,
 
             ref used_trait_imports,
             tainted_by_errors,
@@ -798,7 +794,7 @@ impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for TypeckTables<'gcx> {
             closure_kind_origins.hash_stable(hcx, hasher);
             liberated_fn_sigs.hash_stable(hcx, hasher);
             fru_field_types.hash_stable(hcx, hasher);
-            cast_kinds.hash_stable(hcx, hasher);
+            coercion_casts.hash_stable(hcx, hasher);
             used_trait_imports.hash_stable(hcx, hasher);
             tainted_by_errors.hash_stable(hcx, hasher);
             free_region_map.hash_stable(hcx, hasher);

src/librustc_mir/hair/cx/expr.rs

@@ -651,8 +651,10 @@ fn make_mirror_unadjusted<'a, 'gcx, 'tcx>(cx: &mut Cx<'a, 'gcx, 'tcx>,
                 user_ty,
             );
 
-            let source_ty = cx.tables().expr_ty(source);
-            let cast = if source_ty == expr_ty {
+            // Check to see if this cast is a "coercion cast", where the cast is actually done
+            // using a coercion (or is a no-op).
+            let cast = if cx.tables().is_coercion_cast(&source.hir_id)
+            {
                 // Convert the lexpr to a vexpr.
                 ExprKind::Use { source: source.to_ref() }
             } else {

src/librustc_typeck/check/cast.rs

@@ -428,13 +428,12 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
         } else if self.try_coercion_cast(fcx) {
             self.trivial_cast_lint(fcx);
             debug!(" -> CoercionCast");
-            fcx.tables.borrow_mut().cast_kinds_mut().insert(self.expr.hir_id,
-                                                            CastKind::CoercionCast);
+            fcx.tables.borrow_mut().set_coercion_cast(&self.expr.hir_id);
+
         } else {
             match self.do_check(fcx) {
                 Ok(k) => {
                     debug!(" -> {:?}", k);
-                    fcx.tables.borrow_mut().cast_kinds_mut().insert(self.expr.hir_id, k);
                 }
                 Err(e) => self.report_cast_error(fcx, e),
             };

src/librustc_typeck/check/writeback.rs

@@ -50,7 +50,6 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         wbcx.visit_liberated_fn_sigs();
         wbcx.visit_fru_field_types();
         wbcx.visit_opaque_types(body.value.span);
-        wbcx.visit_cast_types();
         wbcx.visit_free_region_map();
         wbcx.visit_user_provided_tys();
         wbcx.visit_user_provided_sigs();
@@ -355,22 +354,6 @@ impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
         }
     }
 
-    fn visit_cast_types(&mut self) {
-        let fcx_tables = self.fcx.tables.borrow();
-        let fcx_cast_kinds = fcx_tables.cast_kinds();
-        debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
-        let mut self_cast_kinds = self.tables.cast_kinds_mut();
-        let common_local_id_root = fcx_tables.local_id_root.unwrap();
-
-        for (&local_id, &cast_kind) in fcx_cast_kinds.iter() {
-            let hir_id = hir::HirId {
-                owner: common_local_id_root.index,
-                local_id,
-            };
-            self_cast_kinds.insert(hir_id, cast_kind);
-        }
-    }
-
     fn visit_free_region_map(&mut self) {
         let free_region_map = self.tcx()
             .lift_to_global(&self.fcx.tables.borrow().free_region_map);