Rollup of 33 pull requests

.gitignore

@@ -57,6 +57,7 @@ __pycache__/
 .project
 .settings/
 .valgrindrc
+.vscode/
 /*-*-*-*/
 /*-*-*/
 /Makefile

src/doc/book/crates-and-modules.md

@@ -22,6 +22,7 @@ As an example, let’s make a *phrases* crate, which will give us various phrase
 in different languages. To keep things simple, we’ll stick to ‘greetings’ and
 ‘farewells’ as two kinds of phrases, and use English and Japanese (日本語) as
 two languages for those phrases to be in. We’ll use this module layout:
+
 ```text
                                     +-----------+
                                 +---| greetings |

src/doc/book/patterns.md

@@ -109,14 +109,14 @@ struct Point {
     y: i32,
 }
 
-let origin = Point { x: 0, y: 0 };
+let point = Point { x: 2, y: 3 };
 
-match origin {
+match point {
     Point { x, .. } => println!("x is {}", x),
 }
 ```
 
-This prints `x is 0`.
+This prints `x is 2`.
 
 You can do this kind of match on any member, not only the first:
 
@@ -126,14 +126,14 @@ struct Point {
     y: i32,
 }
 
-let origin = Point { x: 0, y: 0 };
+let point = Point { x: 2, y: 3 };
 
-match origin {
+match point {
     Point { y, .. } => println!("y is {}", y),
 }
 ```
 
-This prints `y is 0`.
+This prints `y is 3`.
 
 This ‘destructuring’ behavior works on any compound data type, like
 [tuples][tuples] or [enums][enums].

src/doc/reference.md

@@ -3039,7 +3039,7 @@ The precedence of Rust binary operators is ordered as follows, going from
 strong to weak:
 
 ```{.text .precedence}
-as
+as :
 * / %
 + -
 << >>
@@ -3050,6 +3050,7 @@ as
 &&
 ||
 .. ...
+<-
 =
 ```
 

src/libcollections/string.rs

@@ -1180,7 +1180,7 @@ impl String {
     #[inline]
     #[unstable(feature = "insert_str",
                reason = "recent addition",
-               issue = "0")]
+               issue = "35553")]
     pub fn insert_str(&mut self, idx: usize, string: &str) {
         let len = self.len();
         assert!(idx <= len);

src/libcore/macros.rs

@@ -229,14 +229,28 @@ macro_rules! try {
     })
 }
 
-/// Use the `format!` syntax to write data into a buffer.
+/// Write formatted data into a buffer
 ///
-/// This macro is typically used with a buffer of `&mut `[`Write`][write].
+/// This macro accepts any value with `write_fmt` method as a writer, a format string, and a list
+/// of arguments to format.
+///
+/// `write_fmt` method usually comes from an implementation of [`std::fmt::Write`][fmt_write] or
+/// [`std::io::Write`][io_write] traits. These are sometimes called 'writers'.
+///
+/// Passed arguments will be formatted according to the specified format string and the resulting
+/// string will be passed to the writer.
 ///
 /// See [`std::fmt`][fmt] for more information on format syntax.
 ///
+/// Return value is completely dependent on the 'write_fmt' method.
+///
+/// Common return values are: [`Result`][enum_result], [`io::Result`][type_result]
+///
 /// [fmt]: ../std/fmt/index.html
-/// [write]: ../std/io/trait.Write.html
+/// [fmt_write]: ../std/fmt/trait.Write.html
+/// [io_write]: ../std/io/trait.Write.html
+/// [enum_result]: ../std/result/enum.Result.html
+/// [type_result]: ../std/io/type.Result.html
 ///
 /// # Examples
 ///
@@ -255,16 +269,31 @@ macro_rules! write {
     ($dst:expr, $($arg:tt)*) => ($dst.write_fmt(format_args!($($arg)*)))
 }
 
-/// Use the `format!` syntax to write data into a buffer, appending a newline.
-/// On all platforms, the newline is the LINE FEED character (`\n`/`U+000A`)
-/// alone (no additional CARRIAGE RETURN (`\r`/`U+000D`).
+/// Write formatted data into a buffer, with appending a newline.
+///
+/// On all platforms, the newline is the LINE FEED character (`\n`/`U+000A`) alone
+/// (no additional CARRIAGE RETURN (`\r`/`U+000D`).
 ///
-/// This macro is typically used with a buffer of `&mut `[`Write`][write].
+/// This macro accepts any value with `write_fmt` method as a writer, a format string, and a list
+/// of arguments to format.
+///
+/// `write_fmt` method usually comes from an implementation of [`std::fmt::Write`][fmt_write] or
+/// [`std::io::Write`][io_write] traits. These are sometimes called 'writers'.
+///
+/// Passed arguments will be formatted according to the specified format string and the resulting
+/// string will be passed to the writer.
 ///
 /// See [`std::fmt`][fmt] for more information on format syntax.
 ///
+/// Return value is completely dependent on the 'write_fmt' method.
+///
+/// Common return values are: [`Result`][enum_result], [`io::Result`][type_result]
+///
 /// [fmt]: ../std/fmt/index.html
-/// [write]: ../std/io/trait.Write.html
+/// [fmt_write]: ../std/fmt/trait.Write.html
+/// [io_write]: ../std/io/trait.Write.html
+/// [enum_result]: ../std/result/enum.Result.html
+/// [type_result]: ../std/io/type.Result.html
 ///
 /// # Examples
 ///

src/libcore/result.rs

@@ -402,8 +402,8 @@ impl<T, E> Result<T, E> {
     /// ```
     /// fn mutate(r: &mut Result<i32, i32>) {
     ///     match r.as_mut() {
-    ///         Ok(&mut ref mut v) => *v = 42,
-    ///         Err(&mut ref mut e) => *e = 0,
+    ///         Ok(v) => *v = 42,
+    ///         Err(e) => *e = 0,
     ///     }
     /// }
     ///

src/librustc/middle/resolve_lifetime.rs

@@ -718,10 +718,14 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                 let lifetime_j = &lifetimes[j];
 
                 if lifetime_i.lifetime.name == lifetime_j.lifetime.name {
-                    span_err!(self.sess, lifetime_j.lifetime.span, E0263,
-                        "lifetime name `{}` declared twice in \
-                                the same scope",
-                                lifetime_j.lifetime.name);
+                    struct_span_err!(self.sess, lifetime_j.lifetime.span, E0263,
+                                     "lifetime name `{}` declared twice in the same scope",
+                                     lifetime_j.lifetime.name)
+                        .span_label(lifetime_j.lifetime.span,
+                                    &format!("declared twice"))
+                        .span_label(lifetime_i.lifetime.span,
+                                   &format!("previous declaration here"))
+                        .emit();
                 }
             }
 

src/librustc/traits/error_reporting.rs

@@ -670,10 +670,15 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         let mut err = match warning_node_id {
             Some(_) => None,
             None => {
-                Some(struct_span_err!(
-                    self.sess, span, E0038,
-                    "the trait `{}` cannot be made into an object",
-                    self.item_path_str(trait_def_id)))
+                let trait_str = self.item_path_str(trait_def_id);
+                let mut db = struct_span_err!(
+                            self.sess, span, E0038,
+                            "the trait `{}` cannot be made into an object",
+                            trait_str);
+                db.span_label(span,
+                              &format!("the trait `{}` cannot be made \
+                              into an object", trait_str));
+                Some(db)
             }
         };
 

src/librustc_borrowck/borrowck/mod.rs

@@ -760,12 +760,16 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
                                                 lp: &LoanPath<'tcx>,
                                                 assign:
                                                 &move_data::Assignment) {
-        struct_span_err!(
+        let mut err = struct_span_err!(
             self.tcx.sess, span, E0384,
             "re-assignment of immutable variable `{}`",
-            self.loan_path_to_string(lp))
-            .span_note(assign.span, "prior assignment occurs here")
-            .emit();
+            self.loan_path_to_string(lp));
+        err.span_label(span, &format!("re-assignment of immutable variable"));
+        if span != assign.span {
+            err.span_label(assign.span, &format!("first assignment to `{}`",
+                                              self.loan_path_to_string(lp)));
+        }
+        err.emit();
     }
 
     pub fn span_err(&self, s: Span, m: &str) {

src/librustc_const_eval/check_match.rs

@@ -235,12 +235,7 @@ fn check_expr(cx: &mut MatchCheckCtxt, ex: &hir::Expr) {
                 .flat_map(|arm| &arm.0)
                 .map(|pat| vec![wrap_pat(cx, &pat)])
                 .collect();
-            let match_span = Span {
-                lo: ex.span.lo,
-                hi: scrut.span.hi,
-                expn_id: ex.span.expn_id
-            };
-            check_exhaustive(cx, match_span, &matrix, source);
+            check_exhaustive(cx, scrut.span, &matrix, source);
         },
         _ => ()
     }
@@ -316,7 +311,10 @@ fn check_arms(cx: &MatchCheckCtxt,
                                 let &(ref first_arm_pats, _) = &arms[0];
                                 let first_pat = &first_arm_pats[0];
                                 let span = first_pat.span;
-                                span_err!(cx.tcx.sess, span, E0162, "irrefutable if-let pattern");
+                                struct_span_err!(cx.tcx.sess, span, E0162,
+                                                "irrefutable if-let pattern")
+                                    .span_label(span, &format!("irrefutable pattern"))
+                                    .emit();
                                 printed_if_let_err = true;
                             }
                         },
@@ -1112,9 +1110,15 @@ fn check_legality_of_move_bindings(cx: &MatchCheckCtxt,
 
         // x @ Foo(..) is legal, but x @ Foo(y) isn't.
         if sub.map_or(false, |p| pat_contains_bindings(&p)) {
-            span_err!(cx.tcx.sess, p.span, E0007, "cannot bind by-move with sub-bindings");
+            struct_span_err!(cx.tcx.sess, p.span, E0007,
+                             "cannot bind by-move with sub-bindings")
+                .span_label(p.span, &format!("binds an already bound by-move value by moving it"))
+                .emit();
         } else if has_guard {
-            span_err!(cx.tcx.sess, p.span, E0008, "cannot bind by-move into a pattern guard");
+            struct_span_err!(cx.tcx.sess, p.span, E0008,
+                      "cannot bind by-move into a pattern guard")
+                .span_label(p.span, &format!("moves value into pattern guard"))
+                .emit();
         } else if by_ref_span.is_some() {
             let mut err = struct_span_err!(cx.tcx.sess, p.span, E0009,
                                            "cannot bind by-move and by-ref in the same pattern");

src/librustc_mir/transform/qualify_consts.rs

@@ -617,9 +617,12 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
                     if !allow {
                         self.add(Qualif::NOT_CONST);
                         if self.mode != Mode::Fn {
-                            span_err!(self.tcx.sess, self.span, E0017,
-                                      "references in {}s may only refer \
-                                       to immutable values", self.mode);
+                            struct_span_err!(self.tcx.sess,  self.span, E0017,
+                                             "references in {}s may only refer \
+                                              to immutable values", self.mode)
+                                .span_label(self.span, &format!("{}s require immutable values",
+                                                                self.mode))
+                                .emit();
                         }
                     }
                 } else {

src/librustc_resolve/lib.rs

@@ -412,7 +412,9 @@ fn resolve_struct_error<'b, 'a: 'b, 'c>(resolver: &'b Resolver<'a>,
             struct_span_err!(resolver.session, span, E0432, "{}", msg)
         }
         ResolutionError::FailedToResolve(msg) => {
-            struct_span_err!(resolver.session, span, E0433, "failed to resolve. {}", msg)
+            let mut err = struct_span_err!(resolver.session, span, E0433, "failed to resolve. {}", msg);
+            err.span_label(span, &msg);
+            err
         }
         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
             struct_span_err!(resolver.session,

src/librustc_typeck/astconv.rs

@@ -360,8 +360,11 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                 self.convert_angle_bracketed_parameters(rscope, span, decl_generics, data)
             }
             hir::ParenthesizedParameters(..) => {
-                span_err!(tcx.sess, span, E0214,
-                          "parenthesized parameters may only be used with a trait");
+                struct_span_err!(tcx.sess, span, E0214,
+                          "parenthesized parameters may only be used with a trait")
+                    .span_label(span, &format!("only traits may use parentheses"))
+                    .emit();
+
                 let ty_param_defs = decl_generics.types.get_slice(TypeSpace);
                 (Substs::empty(),
                  ty_param_defs.iter().map(|_| tcx.types.err).collect(),
@@ -1201,10 +1204,13 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
         }
 
         for (trait_def_id, name) in associated_types {
-            span_err!(tcx.sess, span, E0191,
+            struct_span_err!(tcx.sess, span, E0191,
                 "the value of the associated type `{}` (from the trait `{}`) must be specified",
                         name,
-                        tcx.item_path_str(trait_def_id));
+                        tcx.item_path_str(trait_def_id))
+                        .span_label(span, &format!(
+                            "missing associated type `{}` value", name))
+                        .emit();
         }
 
         tcx.mk_trait(object.principal, object.bounds)
@@ -1281,10 +1287,12 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
         }
 
         if bounds.len() > 1 {
-            let mut err = struct_span_err!(self.tcx().sess, span, E0221,
-                                           "ambiguous associated type `{}` in bounds of `{}`",
-                                           assoc_name,
-                                           ty_param_name);
+            let mut err = struct_span_err!(
+                self.tcx().sess, span, E0221,
+                "ambiguous associated type `{}` in bounds of `{}`",
+                assoc_name,
+                ty_param_name);
+            err.span_label(span, &format!("ambiguous associated type `{}`", assoc_name));
 
             for bound in &bounds {
                 span_note!(&mut err, span,

src/librustc_typeck/check/_match.rs

@@ -347,9 +347,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 if let ty::TyTrait(..) = mt.ty.sty {
                     // This is "x = SomeTrait" being reduced from
                     // "let &x = &SomeTrait" or "let box x = Box<SomeTrait>", an error.
-                    span_err!(self.tcx.sess, span, E0033,
-                              "type `{}` cannot be dereferenced",
-                              self.ty_to_string(expected));
+                    let type_str = self.ty_to_string(expected);
+                    struct_span_err!(self.tcx.sess, span, E0033,
+                              "type `{}` cannot be dereferenced", type_str)
+                        .span_label(span, &format!("type `{}` cannot be dereferenced", type_str))
+                        .emit();
                     return false
                 }
             }
@@ -633,10 +635,23 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 self.check_pat(&subpat, field_ty);
             }
         } else {
-            span_err!(tcx.sess, pat.span, E0023,
-                      "this pattern has {} field{s}, but the corresponding {} has {} field{s}",
-                      subpats.len(), def.kind_name(), variant.fields.len(),
-                      s = if variant.fields.len() == 1 {""} else {"s"});
+            let subpats_ending = if subpats.len() == 1 {
+                ""
+            } else {
+                "s"
+            };
+            let fields_ending = if variant.fields.len() == 1 {
+                ""
+            } else {
+                "s"
+            };
+            struct_span_err!(tcx.sess, pat.span, E0023,
+                             "this pattern has {} field{}, but the corresponding {} has {} field{}",
+                             subpats.len(), subpats_ending, def.kind_name(),
+                             variant.fields.len(),  fields_ending)
+                .span_label(pat.span, &format!("expected {} field{}, found {}",
+                                               variant.fields.len(), fields_ending, subpats.len()))
+                .emit();
             on_error();
         }
     }
@@ -682,10 +697,16 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                     field_map.get(&field.name)
                         .map(|f| self.field_ty(span, f, substs))
                         .unwrap_or_else(|| {
-                            span_err!(tcx.sess, span, E0026,
-                                "struct `{}` does not have a field named `{}`",
-                                tcx.item_path_str(variant.did),
-                                field.name);
+                            struct_span_err!(tcx.sess, span, E0026,
+                                             "struct `{}` does not have a field named `{}`",
+                                             tcx.item_path_str(variant.did),
+                                             field.name)
+                                .span_label(span,
+                                            &format!("struct `{}` does not have field `{}`",
+                                                     tcx.item_path_str(variant.did),
+                                                     field.name))
+                                .emit();
+
                             tcx.types.err
                         })
                 }