fixes rust-lang#52482

Author: Saleem Jaffer

Diff for: 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 +409,9 @@ 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>,
+    /// For every coercion cast we add the HIR node ID of the cast
+    /// expression to this set.
+    coercion_casts: ItemLocalSet,
 
     /// Set of trait imports actually used in the method resolution.
     /// This is used for warning unused imports. During type
@@ -456,7 +456,7 @@ 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 +718,19 @@ 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 {
+        validate_hir_id_for_typeck_tables(self.local_id_root, hir_id, true);
+        self.coercion_casts.contains(&hir_id.local_id)
     }
 
-    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, id: ItemLocalId) {
+        self.coercion_casts.insert(id);
+    }
+
+    pub fn coercion_casts(&self) -> &ItemLocalSet {
+        &self.coercion_casts
     }
+
 }
 
 impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for TypeckTables<'gcx> {
@@ -753,7 +753,7 @@ 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 +798,7 @@ 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);

Diff for: src/librustc_mir/hair/cx/expr.rs

@@ -8,7 +8,6 @@ use rustc::hir::def::{Def, CtorKind};
 use rustc::mir::interpret::{GlobalId, ErrorHandled};
 use rustc::ty::{self, AdtKind, Ty};
 use rustc::ty::adjustment::{Adjustment, Adjust, AutoBorrow, AutoBorrowMutability};
-use rustc::ty::cast::CastKind as TyCastKind;
 use rustc::ty::subst::{InternalSubsts, SubstsRef};
 use rustc::hir;
 use rustc::hir::def_id::LocalDefId;
@@ -656,11 +655,7 @@ fn make_mirror_unadjusted<'a, 'gcx, 'tcx>(cx: &mut Cx<'a, 'gcx, 'tcx>,
 
             // 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 let Some(&TyCastKind::CoercionCast) =
-                cx.tables()
-                .cast_kinds()
-                .get(source.hir_id)
-            {
+            let cast = if cx.tables().is_coercion_cast(source.hir_id) {
                 // Convert the lexpr to a vexpr.
                 ExprKind::Use { source: source.to_ref() }
             } else {

Diff for: src/librustc_passes/rvalue_promotion.rs

@@ -14,7 +14,7 @@
 // - It's not possible to take the address of a static item with unsafe interior. This is enforced
 // by borrowck::gather_loans
 
-use rustc::ty::cast::CastKind;
+use rustc::ty::cast::CastTy;
 use rustc::hir::def::{Def, CtorKind};
 use rustc::hir::def_id::DefId;
 use rustc::middle::expr_use_visitor as euv;
@@ -319,15 +319,12 @@ fn check_expr_kind<'a, 'tcx>(
         hir::ExprKind::Cast(ref from, _) => {
             let expr_promotability = v.check_expr(from);
             debug!("Checking const cast(id={})", from.hir_id);
-            match v.tables.cast_kinds().get(from.hir_id) {
-                None => {
-                    v.tcx.sess.delay_span_bug(e.span, "no kind for cast");
-                    NotPromotable
-                },
-                Some(&CastKind::PtrAddrCast) | Some(&CastKind::FnPtrAddrCast) => {
-                    NotPromotable
-                }
-                _ => expr_promotability
+            let cast_in = CastTy::from_ty(v.tables.expr_ty(from));
+            let cast_out = CastTy::from_ty(v.tables.expr_ty(e));
+            match (cast_in, cast_out) {
+                (Some(CastTy::FnPtr), Some(CastTy::Int(_))) |
+                (Some(CastTy::Ptr(_)), Some(CastTy::Int(_))) => NotPromotable,
+                (_, _) => expr_promotability
             }
         }
         hir::ExprKind::Path(ref qpath) => {

Diff for: 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.local_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),
             };

Diff for: src/librustc_typeck/check/writeback.rs

@@ -50,7 +50,7 @@ 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_coercion_casts();
         wbcx.visit_free_region_map();
         wbcx.visit_user_provided_tys();
         wbcx.visit_user_provided_sigs();
@@ -355,19 +355,13 @@ impl<'cx, 'gcx, 'tcx> WritebackCx<'cx, 'gcx, 'tcx> {
         }
     }
 
-    fn visit_cast_types(&mut self) {
+    fn visit_coercion_casts(&mut self) {
         let fcx_tables = self.fcx.tables.borrow();
-        let fcx_cast_kinds = fcx_tables.cast_kinds();
+        let fcx_coercion_casts = fcx_tables.coercion_casts();
         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);
+        for local_id in fcx_coercion_casts {
+            self.tables.set_coercion_cast(*local_id);
         }
     }