Rollup of 14 pull requests

src/libcore/iter/range.rs

@@ -263,14 +263,12 @@ impl<A: Step> ops::RangeFrom<A> {
     /// # Examples
     ///
     /// ```
-    /// # #![feature(step_by)]
-    ///
-    /// for i in (0u8..).step_by(2).take(10) {
-    ///     println!("{}", i);
+    /// #![feature(step_by)]
+    /// fn main() {
+    ///     let result: Vec<_> = (0..).step_by(2).take(5).collect();
+    ///     assert_eq!(result, vec![0, 2, 4, 6, 8]);
     /// }
     /// ```
-    ///
-    /// This prints the first ten even natural integers (0 to 18).
     #[unstable(feature = "step_by", reason = "recent addition",
                issue = "27741")]
     pub fn step_by(self, by: A) -> StepBy<A, Self> {
@@ -291,8 +289,10 @@ impl<A: Step> ops::Range<A> {
     ///
     /// ```
     /// #![feature(step_by)]
-    /// let result: Vec<_> = (0..10).step_by(2).collect();
-    /// assert_eq!(result, vec![0, 2, 4, 6, 8]);
+    /// fn main() {
+    ///     let result: Vec<_> = (0..10).step_by(2).collect();
+    ///     assert_eq!(result, vec![0, 2, 4, 6, 8]);
+    /// }
     /// ```
     #[unstable(feature = "step_by", reason = "recent addition",
                issue = "27741")]
@@ -315,20 +315,8 @@ impl<A: Step> ops::RangeInclusive<A> {
     /// ```
     /// #![feature(step_by, inclusive_range_syntax)]
     ///
-    /// for i in (0...10).step_by(2) {
-    ///     println!("{}", i);
-    /// }
-    /// ```
-    ///
-    /// This prints:
-    ///
-    /// ```text
-    /// 0
-    /// 2
-    /// 4
-    /// 6
-    /// 8
-    /// 10
+    /// let result: Vec<_> = (0...10).step_by(2).collect();
+    /// assert_eq!(result, vec![0, 2, 4, 6, 8, 10]);
     /// ```
     #[unstable(feature = "step_by", reason = "recent addition",
                issue = "27741")]

src/libcore/ops.rs

@@ -948,25 +948,55 @@ bitand_impl! { bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 }
 ///
 /// # Examples
 ///
-/// A trivial implementation of `BitOr`. When `Foo | Foo` happens, it ends up
-/// calling `bitor`, and therefore, `main` prints `Bitwise Or-ing!`.
+/// In this example, the `|` operator is lifted to a trivial `Scalar` type.
 ///
 /// ```
 /// use std::ops::BitOr;
 ///
-/// struct Foo;
+/// #[derive(Debug, PartialEq)]
+/// struct Scalar(bool);
 ///
-/// impl BitOr for Foo {
-///     type Output = Foo;
+/// impl BitOr for Scalar {
+///     type Output = Self;
 ///
-///     fn bitor(self, _rhs: Foo) -> Foo {
-///         println!("Bitwise Or-ing!");
-///         self
+///     // rhs is the "right-hand side" of the expression `a | b`
+///     fn bitor(self, rhs: Self) -> Self {
+///         Scalar(self.0 | rhs.0)
+///     }
+/// }
+///
+/// fn main() {
+///     assert_eq!(Scalar(true) | Scalar(true), Scalar(true));
+///     assert_eq!(Scalar(true) | Scalar(false), Scalar(true));
+///     assert_eq!(Scalar(false) | Scalar(true), Scalar(true));
+///     assert_eq!(Scalar(false) | Scalar(false), Scalar(false));
+/// }
+/// ```
+///
+/// In this example, the `BitOr` trait is implemented for a `BooleanVector`
+/// struct.
+///
+/// ```
+/// use std::ops::BitOr;
+///
+/// #[derive(Debug, PartialEq)]
+/// struct BooleanVector(Vec<bool>);
+///
+/// impl BitOr for BooleanVector {
+///     type Output = Self;
+///
+///     fn bitor(self, BooleanVector(rhs): Self) -> Self {
+///         let BooleanVector(lhs) = self;
+///         assert_eq!(lhs.len(), rhs.len());
+///         BooleanVector(lhs.iter().zip(rhs.iter()).map(|(x, y)| *x || *y).collect())
 ///     }
 /// }
 ///
 /// fn main() {
-///     Foo | Foo;
+///     let bv1 = BooleanVector(vec![true, true, false, false]);
+///     let bv2 = BooleanVector(vec![true, false, true, false]);
+///     let expected = BooleanVector(vec![true, true, true, false]);
+///     assert_eq!(bv1 | bv2, expected);
 /// }
 /// ```
 #[lang = "bitor"]
@@ -1001,25 +1031,58 @@ bitor_impl! { bool usize u8 u16 u32 u64 isize i8 i16 i32 i64 }
 ///
 /// # Examples
 ///
-/// A trivial implementation of `BitXor`. When `Foo ^ Foo` happens, it ends up
-/// calling `bitxor`, and therefore, `main` prints `Bitwise Xor-ing!`.
+/// In this example, the `^` operator is lifted to a trivial `Scalar` type.
 ///
 /// ```
 /// use std::ops::BitXor;
 ///
-/// struct Foo;
+/// #[derive(Debug, PartialEq)]
+/// struct Scalar(bool);
 ///
-/// impl BitXor for Foo {
-///     type Output = Foo;
+/// impl BitXor for Scalar {
+///     type Output = Self;
 ///
-///     fn bitxor(self, _rhs: Foo) -> Foo {
-///         println!("Bitwise Xor-ing!");
-///         self
+///     // rhs is the "right-hand side" of the expression `a ^ b`
+///     fn bitxor(self, rhs: Self) -> Self {
+///         Scalar(self.0 ^ rhs.0)
+///     }
+/// }
+///
+/// fn main() {
+///     assert_eq!(Scalar(true) ^ Scalar(true), Scalar(false));
+///     assert_eq!(Scalar(true) ^ Scalar(false), Scalar(true));
+///     assert_eq!(Scalar(false) ^ Scalar(true), Scalar(true));
+///     assert_eq!(Scalar(false) ^ Scalar(false), Scalar(false));
+/// }
+/// ```
+///
+/// In this example, the `BitXor` trait is implemented for a `BooleanVector`
+/// struct.
+///
+/// ```
+/// use std::ops::BitXor;
+///
+/// #[derive(Debug, PartialEq)]
+/// struct BooleanVector(Vec<bool>);
+///
+/// impl BitXor for BooleanVector {
+///     type Output = Self;
+///
+///     fn bitxor(self, BooleanVector(rhs): Self) -> Self {
+///         let BooleanVector(lhs) = self;
+///         assert_eq!(lhs.len(), rhs.len());
+///         BooleanVector(lhs.iter()
+///                          .zip(rhs.iter())
+///                          .map(|(x, y)| (*x || *y) && !(*x && *y))
+///                          .collect())
 ///     }
 /// }
 ///
 /// fn main() {
-///     Foo ^ Foo;
+///     let bv1 = BooleanVector(vec![true, true, false, false]);
+///     let bv2 = BooleanVector(vec![true, false, true, false]);
+///     let expected = BooleanVector(vec![false, true, true, false]);
+///     assert_eq!(bv1 ^ bv2, expected);
 /// }
 /// ```
 #[lang = "bitxor"]

src/librustc_passes/static_recursion.rs

@@ -126,7 +126,7 @@ impl<'a, 'ast: 'a> CheckItemRecursionVisitor<'a, 'ast> {
             idstack: Vec::new(),
         }
     }
-    fn with_item_id_pushed<F>(&mut self, id: ast::NodeId, f: F)
+    fn with_item_id_pushed<F>(&mut self, id: ast::NodeId, f: F, span: Span)
         where F: Fn(&mut Self)
     {
         if self.idstack.iter().any(|&x| x == id) {
@@ -150,7 +150,9 @@ impl<'a, 'ast: 'a> CheckItemRecursionVisitor<'a, 'ast> {
                                      "recursive static");
                 }
             } else {
-                span_err!(self.sess, *self.root_span, E0265, "recursive constant");
+                struct_span_err!(self.sess, span, E0265, "recursive constant")
+                    .span_label(span, &format!("recursion not allowed in constant"))
+                    .emit();
             }
             return;
         }
@@ -203,7 +205,7 @@ impl<'a, 'ast: 'a> CheckItemRecursionVisitor<'a, 'ast> {
 
 impl<'a, 'ast: 'a> Visitor<'ast> for CheckItemRecursionVisitor<'a, 'ast> {
     fn visit_item(&mut self, it: &'ast hir::Item) {
-        self.with_item_id_pushed(it.id, |v| intravisit::walk_item(v, it));
+        self.with_item_id_pushed(it.id, |v| intravisit::walk_item(v, it), it.span);
     }
 
     fn visit_enum_def(&mut self,
@@ -233,16 +235,16 @@ impl<'a, 'ast: 'a> Visitor<'ast> for CheckItemRecursionVisitor<'a, 'ast> {
         // If `maybe_expr` is `None`, that's because no discriminant is
         // specified that affects this variant. Thus, no risk of recursion.
         if let Some(expr) = maybe_expr {
-            self.with_item_id_pushed(expr.id, |v| intravisit::walk_expr(v, expr));
+            self.with_item_id_pushed(expr.id, |v| intravisit::walk_expr(v, expr), expr.span);
         }
     }
 
     fn visit_trait_item(&mut self, ti: &'ast hir::TraitItem) {
-        self.with_item_id_pushed(ti.id, |v| intravisit::walk_trait_item(v, ti));
+        self.with_item_id_pushed(ti.id, |v| intravisit::walk_trait_item(v, ti), ti.span);
     }
 
     fn visit_impl_item(&mut self, ii: &'ast hir::ImplItem) {
-        self.with_item_id_pushed(ii.id, |v| intravisit::walk_impl_item(v, ii));
+        self.with_item_id_pushed(ii.id, |v| intravisit::walk_impl_item(v, ii), ii.span);
     }
 
     fn visit_expr(&mut self, e: &'ast hir::Expr) {

src/librustc_resolve/diagnostics.rs

@@ -1270,7 +1270,42 @@ trait Foo {}
 
 impl Foo for i32 {}
 ```
-"##
+"##,
+
+E0530: r##"
+A binding shadowed something it shouldn't.
+
+Erroneous code example:
+
+```compile_fail,E0530
+static TEST: i32 = 0;
+
+let r: (i32, i32) = (0, 0);
+match r {
+    TEST => {} // error: match bindings cannot shadow statics
+}
+```
+
+To fix this error, just change the binding's name in order to avoid shadowing
+one of the following:
+
+* struct name
+* struct/enum variant
+* static
+* const
+* associated const
+
+Fixed example:
+
+```
+static TEST: i32 = 0;
+
+let r: (i32, i32) = (0, 0);
+match r {
+    something => {} // ok!
+}
+```
+"##,
 
 }
 
@@ -1289,7 +1324,6 @@ register_diagnostics! {
 //  E0419, merged into 531
 //  E0420, merged into 532
 //  E0421, merged into 531
-    E0530, // X bindings cannot shadow Ys
     E0531, // unresolved pattern path kind `name`
     E0532, // expected pattern path kind, found another pattern path kind
 //  E0427, merged into 530

src/librustc_typeck/astconv.rs

@@ -515,12 +515,13 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                 // defaults. This will lead to an ICE if we are not
                 // careful!
                 if default_needs_object_self(def) {
-                    span_err!(tcx.sess, span, E0393,
-                              "the type parameter `{}` must be explicitly specified \
-                               in an object type because its default value `{}` references \
-                               the type `Self`",
-                              def.name,
-                              default);
+                    struct_span_err!(tcx.sess, span, E0393,
+                                     "the type parameter `{}` must be explicitly specified",
+                                     def.name)
+                        .span_label(span, &format!("missing reference to `{}`", def.name))
+                        .note(&format!("because of the default `Self` reference, \
+                                        type parameters must be specified on object types"))
+                        .emit();
                     tcx.types.err
                 } else {
                     // This is a default type parameter.

src/librustc_typeck/check/method/suggest.rs

@@ -242,6 +242,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             MethodError::Ambiguity(sources) => {
                 let mut err = struct_span_err!(self.sess(), span, E0034,
                                                "multiple applicable items in scope");
+                err.span_label(span, &format!("multiple `{}` found", item_name));
 
                 report_candidates(&mut err, sources);
                 err.emit();

src/librustc_typeck/check/mod.rs

@@ -903,14 +903,18 @@ fn report_forbidden_specialization<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 {
     let mut err = struct_span_err!(
         tcx.sess, impl_item.span, E0520,
-        "item `{}` is provided by an `impl` that specializes \
-         another, but the item in the parent `impl` is not \
-         marked `default` and so it cannot be specialized.",
+        "`{}` specializes an item from a parent `impl`, but \
+         neither that item nor the `impl` are marked `default`",
         impl_item.name);
+    err.span_label(impl_item.span, &format!("cannot specialize default item `{}`",
+                                            impl_item.name));
 
     match tcx.span_of_impl(parent_impl) {
         Ok(span) => {
-            err.span_note(span, "parent implementation is here:");
+            err.span_label(span, &"parent `impl` is here");
+            err.note(&format!("to specialize, either the parent `impl` or `{}` \
+                               in the parent `impl` must be marked `default`",
+                              impl_item.name));
         }
         Err(cname) => {
             err.note(&format!("parent implementation is in crate `{}`", cname));
@@ -1204,7 +1208,9 @@ pub fn check_simd<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, sp: Span, id: ast::Node
             }
             let e = fields[0].ty(tcx, substs);
             if !fields.iter().all(|f| f.ty(tcx, substs) == e) {
-                span_err!(tcx.sess, sp, E0076, "SIMD vector should be homogeneous");
+                struct_span_err!(tcx.sess, sp, E0076, "SIMD vector should be homogeneous")
+                                .span_label(sp, &format!("SIMD elements must have the same type"))
+                                .emit();
                 return;
             }
             match e.sty {