Auto merge of #39230 - petrochenkov:nobox, r=eddyb

Refactoring TyBox -> TyAdt

r? @eddyb
cc @Manishearth

src/liballoc/boxed.rs

@@ -103,6 +103,7 @@ pub struct ExchangeHeapSingleton {
 ///
 /// See the [module-level documentation](../../std/boxed/index.html) for more.
 #[lang = "owned_box"]
+#[fundamental]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Box<T: ?Sized>(Unique<T>);
 
@@ -292,6 +293,14 @@ impl<T: ?Sized> Box<T> {
     }
 }
 
+#[cfg(not(stage0))]
+#[stable(feature = "rust1", since = "1.0.0")]
+unsafe impl<#[may_dangle] T: ?Sized> Drop for Box<T> {
+    fn drop(&mut self) {
+        // FIXME: Do nothing, drop is currently performed by compiler.
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Default> Default for Box<T> {
     /// Creates a `Box<T>`, with the `Default` value for T.

src/librustc/infer/freshen.rs

@@ -156,7 +156,6 @@ impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for TypeFreshener<'a, 'gcx, 'tcx> {
             ty::TyUint(..) |
             ty::TyFloat(..) |
             ty::TyAdt(..) |
-            ty::TyBox(..) |
             ty::TyStr |
             ty::TyError |
             ty::TyArray(..) |

src/librustc/middle/mem_categorization.rs

@@ -961,7 +961,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                                     -> cmt<'tcx>
     {
         let ptr = match base_cmt.ty.sty {
-            ty::TyBox(..) => Unique,
+            ty::TyAdt(def, ..) if def.is_box() => Unique,
             ty::TyRawPtr(ref mt) => UnsafePtr(mt.mutbl),
             ty::TyRef(r, mt) => {
                 let bk = ty::BorrowKind::from_mutbl(mt.mutbl);

src/librustc/traits/coherence.rs

@@ -199,7 +199,7 @@ fn orphan_check_trait_ref<'tcx>(tcx: TyCtxt,
 
 fn uncovered_tys<'tcx>(tcx: TyCtxt, ty: Ty<'tcx>, infer_is_local: InferIsLocal)
                        -> Vec<Ty<'tcx>> {
-    if ty_is_local_constructor(tcx, ty, infer_is_local) {
+    if ty_is_local_constructor(ty, infer_is_local) {
         vec![]
     } else if fundamental_ty(tcx, ty) {
         ty.walk_shallow()
@@ -219,13 +219,13 @@ fn is_type_parameter(ty: Ty) -> bool {
 }
 
 fn ty_is_local(tcx: TyCtxt, ty: Ty, infer_is_local: InferIsLocal) -> bool {
-    ty_is_local_constructor(tcx, ty, infer_is_local) ||
+    ty_is_local_constructor(ty, infer_is_local) ||
         fundamental_ty(tcx, ty) && ty.walk_shallow().any(|t| ty_is_local(tcx, t, infer_is_local))
 }
 
 fn fundamental_ty(tcx: TyCtxt, ty: Ty) -> bool {
     match ty.sty {
-        ty::TyBox(..) | ty::TyRef(..) => true,
+        ty::TyRef(..) => true,
         ty::TyAdt(def, _) => def.is_fundamental(),
         ty::TyDynamic(ref data, ..) => {
             data.principal().map_or(false, |p| tcx.has_attr(p.def_id(), "fundamental"))
@@ -234,7 +234,7 @@ fn fundamental_ty(tcx: TyCtxt, ty: Ty) -> bool {
     }
 }
 
-fn ty_is_local_constructor(tcx: TyCtxt, ty: Ty, infer_is_local: InferIsLocal)-> bool {
+fn ty_is_local_constructor(ty: Ty, infer_is_local: InferIsLocal)-> bool {
     debug!("ty_is_local_constructor({:?})", ty);
 
     match ty.sty {
@@ -265,11 +265,6 @@ fn ty_is_local_constructor(tcx: TyCtxt, ty: Ty, infer_is_local: InferIsLocal)->
             def.did.is_local()
         }
 
-        ty::TyBox(_) => { // Box<T>
-            let krate = tcx.lang_items.owned_box().map(|d| d.krate);
-            krate == Some(LOCAL_CRATE)
-        }
-
         ty::TyDynamic(ref tt, ..) => {
             tt.principal().map_or(false, |p| p.def_id().is_local())
         }

src/librustc/traits/error_reporting.rs

@@ -154,7 +154,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 ty::TyStr => Some(2),
                 ty::TyInt(..) | ty::TyUint(..) | ty::TyInfer(ty::IntVar(..)) => Some(3),
                 ty::TyFloat(..) | ty::TyInfer(ty::FloatVar(..)) => Some(4),
-                ty::TyBox(..) | ty::TyRef(..) | ty::TyRawPtr(..) => Some(5),
+                ty::TyRef(..) | ty::TyRawPtr(..) => Some(5),
                 ty::TyArray(..) | ty::TySlice(..) => Some(6),
                 ty::TyFnDef(..) | ty::TyFnPtr(..) => Some(7),
                 ty::TyDynamic(..) => Some(8),

src/librustc/traits/select.rs

@@ -1735,7 +1735,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
             ty::TyInfer(ty::IntVar(_)) | ty::TyInfer(ty::FloatVar(_)) |
             ty::TyUint(_) | ty::TyInt(_) | ty::TyBool | ty::TyFloat(_) |
             ty::TyFnDef(..) | ty::TyFnPtr(_) | ty::TyRawPtr(..) |
-            ty::TyChar | ty::TyBox(_) | ty::TyRef(..) |
+            ty::TyChar | ty::TyRef(..) |
             ty::TyArray(..) | ty::TyClosure(..) | ty::TyNever |
             ty::TyError => {
                 // safe for everything
@@ -1788,7 +1788,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                 Where(ty::Binder(Vec::new()))
             }
 
-            ty::TyBox(_) | ty::TyDynamic(..) | ty::TyStr | ty::TySlice(..) |
+            ty::TyDynamic(..) | ty::TyStr | ty::TySlice(..) |
             ty::TyClosure(..) |
             ty::TyRef(_, ty::TypeAndMut { ty: _, mutbl: hir::MutMutable }) => {
                 Never
@@ -1865,10 +1865,6 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
                      t);
             }
 
-            ty::TyBox(referent_ty) => {  // Box<T>
-                vec![referent_ty]
-            }
-
             ty::TyRawPtr(ty::TypeAndMut { ty: element_ty, ..}) |
             ty::TyRef(_, ty::TypeAndMut { ty: element_ty, ..}) => {
                 vec![element_ty]

src/librustc/ty/contents.rs

@@ -56,12 +56,8 @@ def_type_content_sets! {
         // InteriorAll                         = 0b00000000__00000000__1111,
 
         // Things that are owned by the value (second and third nibbles):
-        OwnsOwned                           = 0b0000_0000__0000_0001__0000,
         OwnsDtor                            = 0b0000_0000__0000_0010__0000,
-        OwnsAll                             = 0b0000_0000__1111_1111__0000,
-
-        // Things that mean drop glue is necessary
-        NeedsDrop                           = 0b0000_0000__0000_0111__0000,
+        // OwnsAll                             = 0b0000_0000__1111_1111__0000,
 
         // All bits
         All                                 = 0b1111_1111__1111_1111__1111
@@ -77,10 +73,6 @@ impl TypeContents {
         (self.bits & tc.bits) != 0
     }
 
-    pub fn owns_owned(&self) -> bool {
-        self.intersects(TC::OwnsOwned)
-    }
-
     pub fn interior_param(&self) -> bool {
         self.intersects(TC::InteriorParam)
     }
@@ -90,12 +82,7 @@ impl TypeContents {
     }
 
     pub fn needs_drop(&self, _: TyCtxt) -> bool {
-        self.intersects(TC::NeedsDrop)
-    }
-
-    /// Includes only those bits that still apply when indirected through a `Box` pointer
-    pub fn owned_pointer(&self) -> TypeContents {
-        TC::OwnsOwned | (*self & TC::OwnsAll)
+        self.intersects(TC::OwnsDtor)
     }
 
     pub fn union<I, T, F>(v: I, mut f: F) -> TypeContents where
@@ -104,10 +91,6 @@ impl TypeContents {
     {
         v.into_iter().fold(TC::None, |tc, ty| tc | f(ty))
     }
-
-    pub fn has_dtor(&self) -> bool {
-        self.intersects(TC::OwnsDtor)
-    }
 }
 
 impl ops::BitOr for TypeContents {
@@ -191,10 +174,6 @@ impl<'a, 'tcx> ty::TyS<'tcx> {
                     TC::None
                 }
 
-                ty::TyBox(typ) => {
-                    tc_ty(tcx, typ, cache).owned_pointer()
-                }
-
                 ty::TyDynamic(..) => {
                     TC::All - TC::InteriorParam
                 }
@@ -237,7 +216,7 @@ impl<'a, 'tcx> ty::TyS<'tcx> {
 
                     if def.is_union() {
                         // unions don't have destructors regardless of the child types
-                        res = res - TC::NeedsDrop;
+                        res = res - TC::OwnsDtor;
                     }
 
                     if def.has_dtor() {

src/librustc/ty/context.rs

@@ -19,6 +19,7 @@ use hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use hir::map as hir_map;
 use hir::map::DisambiguatedDefPathData;
 use middle::free_region::FreeRegionMap;
+use middle::lang_items;
 use middle::region::RegionMaps;
 use middle::resolve_lifetime;
 use middle::stability;
@@ -1088,7 +1089,7 @@ impl<'a, 'tcx> TyCtxt<'a, 'tcx, 'tcx> {
     pub fn print_debug_stats(self) {
         sty_debug_print!(
             self,
-            TyAdt, TyBox, TyArray, TySlice, TyRawPtr, TyRef, TyFnDef, TyFnPtr,
+            TyAdt, TyArray, TySlice, TyRawPtr, TyRef, TyFnDef, TyFnPtr,
             TyDynamic, TyClosure, TyTuple, TyParam, TyInfer, TyProjection, TyAnon);
 
         println!("Substs interner: #{}", self.interners.substs.borrow().len());
@@ -1336,7 +1337,10 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     }
 
     pub fn mk_box(self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        self.mk_ty(TyBox(ty))
+        let def_id = self.require_lang_item(lang_items::OwnedBoxLangItem);
+        let adt_def = self.lookup_adt_def(def_id);
+        let substs = self.mk_substs(iter::once(Kind::from(ty)));
+        self.mk_ty(TyAdt(adt_def, substs))
     }
 
     pub fn mk_ptr(self, tm: TypeAndMut<'tcx>) -> Ty<'tcx> {

src/librustc/ty/error.rs

@@ -181,7 +181,6 @@ impl<'a, 'gcx, 'lcx, 'tcx> ty::TyS<'tcx> {
             ty::TyTuple(ref tys) if tys.is_empty() => self.to_string(),
 
             ty::TyAdt(def, _) => format!("{} `{}`", def.descr(), tcx.item_path_str(def.did)),
-            ty::TyBox(_) => "box".to_string(),
             ty::TyArray(_, n) => format!("array of {} elements", n),
             ty::TySlice(_) => "slice".to_string(),
             ty::TyRawPtr(_) => "*-ptr".to_string(),

src/librustc/ty/fast_reject.rs

@@ -11,7 +11,6 @@
 use hir::def_id::DefId;
 use ty::{self, Ty, TyCtxt};
 use syntax::ast;
-use middle::lang_items::OwnedBoxLangItem;
 
 use self::SimplifiedType::*;
 
@@ -69,10 +68,6 @@ pub fn simplify_type<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
             // view of possibly unifying
             simplify_type(tcx, mt.ty, can_simplify_params)
         }
-        ty::TyBox(_) => {
-            // treat like we would treat `Box`
-            Some(AdtSimplifiedType(tcx.require_lang_item(OwnedBoxLangItem)))
-        }
         ty::TyClosure(def_id, _) => {
             Some(ClosureSimplifiedType(def_id))
         }

src/librustc/ty/flags.rs

@@ -138,7 +138,7 @@ impl FlagComputation {
                 self.add_region(r);
             }
 
-            &ty::TyBox(tt) | &ty::TyArray(tt, _) | &ty::TySlice(tt) => {
+            &ty::TyArray(tt, _) | &ty::TySlice(tt) => {
                 self.add_ty(tt)
             }
 

src/librustc/ty/item_path.rs

@@ -314,8 +314,7 @@ pub fn characteristic_def_id_of_type(ty: Ty) -> Option<DefId> {
         ty::TyDynamic(data, ..) => data.principal().map(|p| p.def_id()),
 
         ty::TyArray(subty, _) |
-        ty::TySlice(subty) |
-        ty::TyBox(subty) => characteristic_def_id_of_type(subty),
+        ty::TySlice(subty) => characteristic_def_id_of_type(subty),
 
         ty::TyRawPtr(mt) |
         ty::TyRef(_, mt) => characteristic_def_id_of_type(mt.ty),

src/librustc/ty/layout.rs

@@ -1053,6 +1053,23 @@ impl<'a, 'gcx, 'tcx> Layout {
         let dl = &tcx.data_layout;
         assert!(!ty.has_infer_types());
 
+        let ptr_layout = |pointee: Ty<'gcx>| {
+            let non_zero = !ty.is_unsafe_ptr();
+            let pointee = normalize_associated_type(infcx, pointee);
+            if pointee.is_sized(tcx, &infcx.parameter_environment, DUMMY_SP) {
+                Ok(Scalar { value: Pointer, non_zero: non_zero })
+            } else {
+                let unsized_part = tcx.struct_tail(pointee);
+                let meta = match unsized_part.sty {
+                    ty::TySlice(_) | ty::TyStr => {
+                        Int(dl.ptr_sized_integer())
+                    }
+                    ty::TyDynamic(..) => Pointer,
+                    _ => return Err(LayoutError::Unknown(unsized_part))
+                };
+                Ok(FatPointer { metadata: meta, non_zero: non_zero })
+            }
+        };
 
         let layout = match ty.sty {
             // Basic scalars.
@@ -1082,24 +1099,12 @@ impl<'a, 'gcx, 'tcx> Layout {
             },
 
             // Potentially-fat pointers.
-            ty::TyBox(pointee) |
             ty::TyRef(_, ty::TypeAndMut { ty: pointee, .. }) |
             ty::TyRawPtr(ty::TypeAndMut { ty: pointee, .. }) => {
-                let non_zero = !ty.is_unsafe_ptr();
-                let pointee = normalize_associated_type(infcx, pointee);
-                if pointee.is_sized(tcx, &infcx.parameter_environment, DUMMY_SP) {
-                    Scalar { value: Pointer, non_zero: non_zero }
-                } else {
-                    let unsized_part = tcx.struct_tail(pointee);
-                    let meta = match unsized_part.sty {
-                        ty::TySlice(_) | ty::TyStr => {
-                            Int(dl.ptr_sized_integer())
-                        }
-                        ty::TyDynamic(..) => Pointer,
-                        _ => return Err(LayoutError::Unknown(unsized_part))
-                    };
-                    FatPointer { metadata: meta, non_zero: non_zero }
-                }
+                ptr_layout(pointee)?
+            }
+            ty::TyAdt(def, _) if def.is_box() => {
+                ptr_layout(ty.boxed_ty())?
             }
 
             // Arrays and slices.
@@ -1560,26 +1565,32 @@ impl<'a, 'gcx, 'tcx> SizeSkeleton<'gcx> {
             Err(err) => err
         };
 
+        let ptr_skeleton = |pointee: Ty<'gcx>| {
+            let non_zero = !ty.is_unsafe_ptr();
+            let tail = tcx.struct_tail(pointee);
+            match tail.sty {
+                ty::TyParam(_) | ty::TyProjection(_) => {
+                    assert!(tail.has_param_types() || tail.has_self_ty());
+                    Ok(SizeSkeleton::Pointer {
+                        non_zero: non_zero,
+                        tail: tcx.erase_regions(&tail)
+                    })
+                }
+                _ => {
+                    bug!("SizeSkeleton::compute({}): layout errored ({}), yet \
+                            tail `{}` is not a type parameter or a projection",
+                            ty, err, tail)
+                }
+            }
+        };
+
         match ty.sty {
-            ty::TyBox(pointee) |
             ty::TyRef(_, ty::TypeAndMut { ty: pointee, .. }) |
             ty::TyRawPtr(ty::TypeAndMut { ty: pointee, .. }) => {
-                let non_zero = !ty.is_unsafe_ptr();
-                let tail = tcx.struct_tail(pointee);
-                match tail.sty {
-                    ty::TyParam(_) | ty::TyProjection(_) => {
-                        assert!(tail.has_param_types() || tail.has_self_ty());
-                        Ok(SizeSkeleton::Pointer {
-                            non_zero: non_zero,
-                            tail: tcx.erase_regions(&tail)
-                        })
-                    }
-                    _ => {
-                        bug!("SizeSkeleton::compute({}): layout errored ({}), yet \
-                              tail `{}` is not a type parameter or a projection",
-                             ty, err, tail)
-                    }
-                }
+                ptr_skeleton(pointee)
+            }
+            ty::TyAdt(def, _) if def.is_box() => {
+                ptr_skeleton(ty.boxed_ty())
             }
 
             ty::TyAdt(def, substs) => {