Added error for duplicate bindings of associated type.

Author: Alexander Regueiro

src/librustc/traits/mod.rs

@@ -50,11 +50,8 @@ pub use self::select::{EvaluationResult, IntercrateAmbiguityCause, OverflowError
 pub use self::specialize::{OverlapError, specialization_graph, translate_substs};
 pub use self::specialize::find_associated_item;
 pub use self::engine::{TraitEngine, TraitEngineExt};
-pub use self::util::elaborate_predicates;
-pub use self::util::supertraits;
-pub use self::util::Supertraits;
-pub use self::util::supertrait_def_ids;
-pub use self::util::SupertraitDefIds;
+pub use self::util::{elaborate_predicates, elaborate_trait_ref, elaborate_trait_refs};
+pub use self::util::{supertraits, supertrait_def_ids, Supertraits, SupertraitDefIds};
 pub use self::util::transitive_bounds;
 
 #[allow(dead_code)]

src/librustc/ty/mod.rs

@@ -544,14 +544,14 @@ impl<'tcx> TyS<'tcx> {
     pub fn is_primitive_ty(&self) -> bool {
         match self.sty {
             TyKind::Bool |
-                TyKind::Char |
-                TyKind::Int(_) |
-                TyKind::Uint(_) |
-                TyKind::Float(_) |
-                TyKind::Infer(InferTy::IntVar(_)) |
-                TyKind::Infer(InferTy::FloatVar(_)) |
-                TyKind::Infer(InferTy::FreshIntTy(_)) |
-                TyKind::Infer(InferTy::FreshFloatTy(_)) => true,
+            TyKind::Char |
+            TyKind::Int(_) |
+            TyKind::Uint(_) |
+            TyKind::Float(_) |
+            TyKind::Infer(InferTy::IntVar(_)) |
+            TyKind::Infer(InferTy::FloatVar(_)) |
+            TyKind::Infer(InferTy::FreshIntTy(_)) |
+            TyKind::Infer(InferTy::FreshFloatTy(_)) => true,
             TyKind::Ref(_, x, _) => x.is_primitive_ty(),
             _ => false,
         }
@@ -1042,15 +1042,15 @@ impl<'a, 'gcx, 'tcx> GenericPredicates<'tcx> {
 
 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
 pub enum Predicate<'tcx> {
-    /// Corresponds to `where Foo : Bar<A,B,C>`. `Foo` here would be
+    /// Corresponds to `where Foo: Bar<A,B,C>`. `Foo` here would be
     /// the `Self` type of the trait reference and `A`, `B`, and `C`
     /// would be the type parameters.
     Trait(PolyTraitPredicate<'tcx>),
 
-    /// where `'a : 'b`
+    /// where `'a: 'b`
     RegionOutlives(PolyRegionOutlivesPredicate<'tcx>),
 
-    /// where `T : 'a`
+    /// where `T: 'a`
     TypeOutlives(PolyTypeOutlivesPredicate<'tcx>),
 
     /// where `<T as TraitRef>::Name == X`, approximately.
@@ -1063,7 +1063,7 @@ pub enum Predicate<'tcx> {
     /// trait must be object-safe
     ObjectSafe(DefId),
 
-    /// No direct syntax. May be thought of as `where T : FnFoo<...>`
+    /// No direct syntax. May be thought of as `where T: FnFoo<...>`
     /// for some substitutions `...` and `T` being a closure type.
     /// Satisfied (or refuted) once we know the closure's kind.
     ClosureKind(DefId, ClosureSubsts<'tcx>, ClosureKind),
@@ -1112,11 +1112,11 @@ impl<'a, 'gcx, 'tcx> Predicate<'tcx> {
         //
         // Let's start with an easy case. Consider two traits:
         //
-        //     trait Foo<'a> : Bar<'a,'a> { }
+        //     trait Foo<'a>: Bar<'a,'a> { }
         //     trait Bar<'b,'c> { }
         //
-        // Now, if we have a trait reference `for<'x> T : Foo<'x>`, then
-        // we can deduce that `for<'x> T : Bar<'x,'x>`. Basically, if we
+        // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
+        // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
         // knew that `Foo<'x>` (for any 'x) then we also know that
         // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
         // normal substitution.
@@ -1129,21 +1129,21 @@ impl<'a, 'gcx, 'tcx> Predicate<'tcx> {
         //
         // Another example to be careful of is this:
         //
-        //     trait Foo1<'a> : for<'b> Bar1<'a,'b> { }
+        //     trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
         //     trait Bar1<'b,'c> { }
         //
-        // Here, if we have `for<'x> T : Foo1<'x>`, then what do we know?
-        // The answer is that we know `for<'x,'b> T : Bar1<'x,'b>`. The
+        // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
+        // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
         // reason is similar to the previous example: any impl of
-        // `T:Foo1<'x>` must show that `for<'b> T : Bar1<'x, 'b>`.  So
+        // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`.  So
         // basically we would want to collapse the bound lifetimes from
         // the input (`trait_ref`) and the supertraits.
         //
         // To achieve this in practice is fairly straightforward. Let's
         // consider the more complicated scenario:
         //
-        // - We start out with `for<'x> T : Foo1<'x>`. In this case, `'x`
-        //   has a De Bruijn index of 1. We want to produce `for<'x,'b> T : Bar1<'x,'b>`,
+        // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
+        //   has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
         //   where both `'x` and `'b` would have a DB index of 1.
         //   The substitution from the input trait-ref is therefore going to be
         //   `'a => 'x` (where `'x` has a DB index of 1).
@@ -1219,7 +1219,7 @@ impl<'tcx> PolyTraitPredicate<'tcx> {
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
-pub struct OutlivesPredicate<A,B>(pub A, pub B); // `A : B`
+pub struct OutlivesPredicate<A,B>(pub A, pub B); // `A: B`
 pub type PolyOutlivesPredicate<A,B> = ty::Binder<OutlivesPredicate<A,B>>;
 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>,
                                                            ty::Region<'tcx>>;
@@ -2476,7 +2476,7 @@ impl<'tcx> TyS<'tcx> {
     ///
     /// Note: prefer `ty.walk()` where possible.
     pub fn maybe_walk<F>(&'tcx self, mut f: F)
-        where F : FnMut(Ty<'tcx>) -> bool
+        where F: FnMut(Ty<'tcx>) -> bool
     {
         let mut walker = self.walk();
         while let Some(ty) = walker.next() {

src/librustc/ty/sty.rs

@@ -627,7 +627,7 @@ impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
 /// A complete reference to a trait. These take numerous guises in syntax,
 /// but perhaps the most recognizable form is in a where clause:
 ///
-///     T : Foo<U>
+///     T: Foo<U>
 ///
 /// This would be represented by a trait-reference where the def-id is the
 /// def-id for the trait `Foo` and the substs define `T` as parameter 0,
@@ -637,8 +637,8 @@ impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
 /// that case the `Self` parameter is absent from the substitutions.
 ///
 /// Note that a `TraitRef` introduces a level of region binding, to
-/// account for higher-ranked trait bounds like `T : for<'a> Foo<&'a
-/// U>` or higher-ranked object types.
+/// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>`
+/// or higher-ranked object types.
 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
 pub struct TraitRef<'tcx> {
     pub def_id: DefId,
@@ -663,7 +663,7 @@ impl<'tcx> TraitRef<'tcx> {
         self.substs.type_at(0)
     }
 
-    pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
+    pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
         // Select only the "input types" from a trait-reference. For
         // now this is all the types that appear in the
         // trait-reference, but it should eventually exclude
@@ -886,16 +886,16 @@ pub struct ProjectionTy<'tcx> {
     /// The parameters of the associated item.
     pub substs: &'tcx Substs<'tcx>,
 
-    /// The DefId of the TraitItem for the associated type N.
+    /// The `DefId` of the `TraitItem` for the associated type `N`.
     ///
-    /// Note that this is not the DefId of the TraitRef containing this
-    /// associated type, which is in tcx.associated_item(item_def_id).container.
+    /// Note that this is not the `DefId` of the `TraitRef` containing this
+    /// associated type, which is in `tcx.associated_item(item_def_id).container`.
     pub item_def_id: DefId,
 }
 
 impl<'a, 'tcx> ProjectionTy<'tcx> {
-    /// Construct a ProjectionTy by searching the trait from trait_ref for the
-    /// associated item named item_name.
+    /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the
+    /// associated item named `item_name`.
     pub fn from_ref_and_name(
         tcx: TyCtxt<'_, '_, '_>, trait_ref: ty::TraitRef<'tcx>, item_name: Ident
     ) -> ProjectionTy<'tcx> {

src/librustc/ty/subst.rs

@@ -27,7 +27,7 @@ use std::marker::PhantomData;
 use std::mem;
 use std::num::NonZeroUsize;
 
-/// An entity in the Rust typesystem, which can be one of
+/// An entity in the Rust type system, which can be one of
 /// several kinds (only types and lifetimes for now).
 /// To reduce memory usage, a `Kind` is a interned pointer,
 /// with the lowest 2 bits being reserved for a tag to
@@ -171,17 +171,17 @@ impl<'tcx> Decodable for Kind<'tcx> {
 pub type Substs<'tcx> = List<Kind<'tcx>>;
 
 impl<'a, 'gcx, 'tcx> Substs<'tcx> {
-    /// Creates a Substs that maps each generic parameter to itself.
+    /// Creates a `Substs` that maps each generic parameter to itself.
     pub fn identity_for_item(tcx: TyCtxt<'a, 'gcx, 'tcx>, def_id: DefId)
                              -> &'tcx Substs<'tcx> {
         Substs::for_item(tcx, def_id, |param, _| {
             tcx.mk_param_from_def(param)
         })
     }
 
-    /// Creates a Substs for generic parameter definitions,
+    /// Creates a `Substs` for generic parameter definitions,
     /// by calling closures to obtain each kind.
-    /// The closures get to observe the Substs as they're
+    /// The closures get to observe the `Substs` as they're
     /// being built, which can be used to correctly
     /// substitute defaults of generic parameters.
     pub fn for_item<F>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
@@ -242,7 +242,7 @@ impl<'a, 'gcx, 'tcx> Substs<'tcx> {
     }
 
     #[inline]
-    pub fn types(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
+    pub fn types(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
         self.iter().filter_map(|k| {
             if let UnpackedKind::Type(ty) = k.unpack() {
                 Some(ty)
@@ -253,7 +253,7 @@ impl<'a, 'gcx, 'tcx> Substs<'tcx> {
     }
 
     #[inline]
-    pub fn regions(&'a self) -> impl DoubleEndedIterator<Item=ty::Region<'tcx>> + 'a {
+    pub fn regions(&'a self) -> impl DoubleEndedIterator<Item = ty::Region<'tcx>> + 'a {
         self.iter().filter_map(|k| {
             if let UnpackedKind::Lifetime(lt) = k.unpack() {
                 Some(lt)
@@ -332,7 +332,7 @@ impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Substs<'tcx> {}
 // `foo`. Or use `foo.subst_spanned(tcx, substs, Some(span))` when
 // there is more information available (for better errors).
 
-pub trait Subst<'tcx> : Sized {
+pub trait Subst<'tcx>: Sized {
     fn subst<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
                        substs: &[Kind<'tcx>]) -> Self {
         self.subst_spanned(tcx, substs, None)