Auto merge of #35469 - jonathandturner:rollup, r=jonathandturner

Rollup of 21 pull requests

- Successful merges: #35314, #35355, #35357, #35366, #35394, #35410, #35411, #35413, #35417, #35419, #35421, #35429, #35433, #35434, #35436, #35439, #35443, #35454, #35455, #35467, #35468
- Failed merges: #35395, #35415

src/libcore/iter/traits.rs

@@ -548,7 +548,7 @@ pub trait ExactSizeIterator: Iterator {
     /// assert_eq!(one_element.next(), None);
     /// ```
     #[inline]
-    #[unstable(feature = "exact_size_is_empty", issue = "0")]
+    #[unstable(feature = "exact_size_is_empty", issue = "35428")]
     fn is_empty(&self) -> bool {
         self.len() == 0
     }

src/librustc/traits/error_reporting.rs

@@ -870,10 +870,12 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
 
 
     fn need_type_info(&self, span: Span, ty: Ty<'tcx>) {
-        span_err!(self.tcx.sess, span, E0282,
-                  "unable to infer enough type information about `{}`; \
-                   type annotations or generic parameter binding required",
-                  ty);
+        let mut err = struct_span_err!(self.tcx.sess, span, E0282,
+                                       "unable to infer enough type information about `{}`",
+                                       ty);
+        err.note("type annotations or generic parameter binding required");
+        err.span_label(span, &format!("cannot infer type for `{}`", ty));
+        err.emit()
     }
 
     fn note_obligation_cause<T>(&self,

src/librustc_mir/transform/qualify_consts.rs

@@ -686,8 +686,10 @@ impl<'a, 'tcx> Visitor<'tcx> for Qualifier<'a, 'tcx, 'tcx> {
             Rvalue::Box(_) => {
                 self.add(Qualif::NOT_CONST);
                 if self.mode != Mode::Fn {
-                    span_err!(self.tcx.sess, self.span, E0010,
-                              "allocations are not allowed in {}s", self.mode);
+                    struct_span_err!(self.tcx.sess, self.span, E0010,
+                                     "allocations are not allowed in {}s", self.mode)
+                        .span_label(self.span, &format!("allocation not allowed in {}s", self.mode))
+                        .emit();
                 }
             }
 

src/librustc_typeck/astconv.rs

@@ -1215,10 +1215,12 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                                         type_str: &str,
                                         trait_str: &str,
                                         name: &str) {
-        span_err!(self.tcx().sess, span, E0223,
-                  "ambiguous associated type; specify the type using the syntax \
-                   `<{} as {}>::{}`",
-                  type_str, trait_str, name);
+        struct_span_err!(self.tcx().sess, span, E0223, "ambiguous associated type")
+            .span_label(span, &format!("ambiguous associated type"))
+            .note(&format!("specify the type using the syntax `<{} as {}>::{}`",
+                  type_str, trait_str, name))
+            .emit();
+
     }
 
     // Search for a bound on a type parameter which includes the associated item
@@ -2095,8 +2097,11 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
 
         if !trait_bounds.is_empty() {
             let b = &trait_bounds[0];
-            span_err!(self.tcx().sess, b.trait_ref.path.span, E0225,
-                      "only the builtin traits can be used as closure or object bounds");
+            let span = b.trait_ref.path.span;
+            struct_span_err!(self.tcx().sess, span, E0225,
+                             "only the builtin traits can be used as closure or object bounds")
+                .span_label(span, &format!("non-builtin trait used as bounds"))
+                .emit();
         }
 
         let region_bound =
@@ -2255,20 +2260,27 @@ fn check_type_argument_count(tcx: TyCtxt, span: Span, supplied: usize,
         } else {
             "expected"
         };
-        span_err!(tcx.sess, span, E0243,
-                  "wrong number of type arguments: {} {}, found {}",
-                  expected, required, supplied);
+        struct_span_err!(tcx.sess, span, E0243, "wrong number of type arguments")
+            .span_label(
+                span,
+                &format!("{} {} type arguments, found {}", expected, required, supplied)
+            )
+            .emit();
     } else if supplied > accepted {
-        let expected = if required < accepted {
-            "expected at most"
+        let expected = if required == 0 {
+            "expected no".to_string()
+        } else if required < accepted {
+            format!("expected at most {}", accepted)
         } else {
-            "expected"
+            format!("expected {}", accepted)
         };
-        span_err!(tcx.sess, span, E0244,
-                  "wrong number of type arguments: {} {}, found {}",
-                  expected,
-                  accepted,
-                  supplied);
+
+        struct_span_err!(tcx.sess, span, E0244, "wrong number of type arguments")
+            .span_label(
+                span,
+                &format!("{} type arguments, found {}", expected, supplied)
+            )
+            .emit();
     }
 }
 

src/librustc_typeck/check/_match.rs

@@ -93,13 +93,12 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                         end.span
                     };
 
-                    // Note: spacing here is intentional, we want a space before "start" and "end".
-                    span_err!(tcx.sess, span, E0029,
-                              "only char and numeric types are allowed in range patterns\n \
-                               start type: {}\n end type: {}",
-                              self.ty_to_string(lhs_ty),
-                              self.ty_to_string(rhs_ty)
-                    );
+                    struct_span_err!(tcx.sess, span, E0029,
+                        "only char and numeric types are allowed in range patterns")
+                        .span_label(span, &format!("ranges require char or numeric types"))
+                        .note(&format!("start type: {}", self.ty_to_string(lhs_ty)))
+                        .note(&format!("end type: {}", self.ty_to_string(rhs_ty)))
+                        .emit();
                     return;
                 }
 
@@ -700,9 +699,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             for field in variant.fields
                 .iter()
                 .filter(|field| !used_fields.contains_key(&field.name)) {
-                span_err!(tcx.sess, span, E0027,
-                    "pattern does not mention field `{}`",
-                    field.name);
+                struct_span_err!(tcx.sess, span, E0027,
+                                "pattern does not mention field `{}`",
+                                field.name)
+                                .span_label(span, &format!("missing field `{}`", field.name))
+                                .emit();
             }
         }
     }

src/librustc_typeck/check/callee.rs

@@ -28,7 +28,9 @@ use rustc::hir;
 /// method that is called)
 pub fn check_legal_trait_for_method_call(ccx: &CrateCtxt, span: Span, trait_id: DefId) {
     if ccx.tcx.lang_items.drop_trait() == Some(trait_id) {
-        span_err!(ccx.tcx.sess, span, E0040, "explicit use of destructor method");
+        struct_span_err!(ccx.tcx.sess, span, E0040, "explicit use of destructor method")
+            .span_label(span, &format!("call to destructor method"))
+            .emit();
     }
 }
 

src/librustc_typeck/check/compare_method.rs

@@ -59,19 +59,33 @@ pub fn compare_impl_method<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
         (&ty::ExplicitSelfCategory::Static,
          &ty::ExplicitSelfCategory::Static) => {}
         (&ty::ExplicitSelfCategory::Static, _) => {
-            span_err!(tcx.sess, impl_m_span, E0185,
+            let mut err = struct_span_err!(tcx.sess, impl_m_span, E0185,
                 "method `{}` has a `{}` declaration in the impl, \
                         but not in the trait",
                         trait_m.name,
                         impl_m.explicit_self);
+            err.span_label(impl_m_span, &format!("`{}` used in impl",
+                                                 impl_m.explicit_self));
+            if let Some(span) = tcx.map.span_if_local(trait_m.def_id) {
+                err.span_label(span, &format!("trait declared without `{}`",
+                                              impl_m.explicit_self));
+            }
+            err.emit();
             return;
         }
         (_, &ty::ExplicitSelfCategory::Static) => {
-            span_err!(tcx.sess, impl_m_span, E0186,
+            let mut err = struct_span_err!(tcx.sess, impl_m_span, E0186,
                 "method `{}` has a `{}` declaration in the trait, \
                         but not in the impl",
                         trait_m.name,
                         trait_m.explicit_self);
+            err.span_label(impl_m_span, &format!("expected `{}` in impl",
+                                                  trait_m.explicit_self));
+            if let Some(span) = tcx.map.span_if_local(trait_m.def_id) {
+                err.span_label(span, & format!("`{}` used in trait",
+                                               trait_m.explicit_self));
+            }
+            err.emit();
             return;
         }
         _ => {

src/librustc_typeck/check/mod.rs

@@ -1136,11 +1136,16 @@ fn check_impl_items_against_trait<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
     }
 
     if !missing_items.is_empty() {
-        span_err!(tcx.sess, impl_span, E0046,
+        struct_span_err!(tcx.sess, impl_span, E0046,
             "not all trait items implemented, missing: `{}`",
             missing_items.iter()
                   .map(|name| name.to_string())
                   .collect::<Vec<_>>().join("`, `"))
+            .span_label(impl_span, &format!("missing `{}` in implementation",
+                missing_items.iter()
+                    .map(|name| name.to_string())
+                    .collect::<Vec<_>>().join("`, `"))
+            ).emit();
     }
 
     if !invalidated_items.is_empty() {

src/librustc_typeck/check/writeback.rs

@@ -441,13 +441,19 @@ impl<'cx, 'gcx, 'tcx> Resolver<'cx, 'gcx, 'tcx> {
         if !self.tcx.sess.has_errors() {
             match self.reason {
                 ResolvingExpr(span) => {
-                    span_err!(self.tcx.sess, span, E0101,
-                        "cannot determine a type for this expression: {}", e);
+                    struct_span_err!(
+                        self.tcx.sess, span, E0101,
+                        "cannot determine a type for this expression: {}", e)
+                        .span_label(span, &format!("cannot resolve type of expression"))
+                        .emit();
                 }
 
                 ResolvingLocal(span) => {
-                    span_err!(self.tcx.sess, span, E0102,
-                        "cannot determine a type for this local variable: {}", e);
+                    struct_span_err!(
+                        self.tcx.sess, span, E0102,
+                        "cannot determine a type for this local variable: {}", e)
+                        .span_label(span, &format!("cannot resolve type of variable"))
+                        .emit();
                 }
 
                 ResolvingPattern(span) => {

src/librustc_typeck/coherence/mod.rs

@@ -311,18 +311,23 @@ impl<'a, 'gcx, 'tcx> CoherenceChecker<'a, 'gcx, 'tcx> {
             match param_env.can_type_implement_copy(tcx, self_type, span) {
                 Ok(()) => {}
                 Err(CopyImplementationError::InfrigingField(name)) => {
-                       span_err!(tcx.sess, span, E0204,
-                                 "the trait `Copy` may not be \
-                                          implemented for this type; field \
-                                          `{}` does not implement `Copy`",
-                                         name)
+                       struct_span_err!(tcx.sess, span, E0204,
+                                 "the trait `Copy` may not be implemented for \
+                                 this type")
+                           .span_label(span, &format!(
+                                 "field `{}` does not implement `Copy`", name)
+                               )
+                           .emit()
+
                 }
                 Err(CopyImplementationError::InfrigingVariant(name)) => {
-                       span_err!(tcx.sess, span, E0205,
+                       struct_span_err!(tcx.sess, span, E0205,
                                  "the trait `Copy` may not be \
-                                          implemented for this type; variant \
+                                          implemented for this type")
+                           .span_label(span, &format!("variant \
                                           `{}` does not implement `Copy`",
-                                         name)
+                                         name))
+                           .emit()
                 }
                 Err(CopyImplementationError::NotAnAdt) => {
                        span_err!(tcx.sess, span, E0206,

src/librustc_typeck/coherence/orphan.rs

@@ -33,10 +33,12 @@ struct OrphanChecker<'cx, 'tcx:'cx> {
 impl<'cx, 'tcx> OrphanChecker<'cx, 'tcx> {
     fn check_def_id(&self, item: &hir::Item, def_id: DefId) {
         if def_id.krate != LOCAL_CRATE {
-            span_err!(self.tcx.sess, item.span, E0116,
+            struct_span_err!(self.tcx.sess, item.span, E0116,
                       "cannot define inherent `impl` for a type outside of the \
-                       crate where the type is defined; define and implement \
-                       a trait or new type instead");
+                       crate where the type is defined")
+                .span_label(item.span, &format!("impl for type defined outside of crate."))
+                .span_note(item.span, &format!("define and implement a trait or new type instead"))
+                .emit();
         }
     }
 
@@ -66,7 +68,7 @@ impl<'cx, 'tcx> OrphanChecker<'cx, 'tcx> {
     fn check_item(&self, item: &hir::Item) {
         let def_id = self.tcx.map.local_def_id(item.id);
         match item.node {
-            hir::ItemImpl(_, _, _, None, _, _) => {
+            hir::ItemImpl(_, _, _, None, ref ty, _) => {
                 // For inherent impls, self type must be a nominal type
                 // defined in this crate.
                 debug!("coherence2::orphan check: inherent impl {}",
@@ -209,11 +211,11 @@ impl<'cx, 'tcx> OrphanChecker<'cx, 'tcx> {
                         return;
                     }
                     _ => {
-                        struct_span_err!(self.tcx.sess, item.span, E0118,
+                        struct_span_err!(self.tcx.sess, ty.span, E0118,
                                          "no base type found for inherent implementation")
-                        .span_help(item.span,
-                                   "either implement a trait on it or create a newtype to wrap it \
-                                    instead")
+                        .span_label(ty.span, &format!("impl requires a base type"))
+                        .note(&format!("either implement a trait on it or create a newtype \
+                                        to wrap it instead"))
                         .emit();
                         return;
                     }
@@ -228,12 +230,14 @@ impl<'cx, 'tcx> OrphanChecker<'cx, 'tcx> {
                 match traits::orphan_check(self.tcx, def_id) {
                     Ok(()) => { }
                     Err(traits::OrphanCheckErr::NoLocalInputType) => {
-                        span_err!(
+                        struct_span_err!(
                             self.tcx.sess, item.span, E0117,
-                            "the impl does not reference any \
-                             types defined in this crate; \
-                             only traits defined in the current crate can be \
-                             implemented for arbitrary types");
+                             "only traits defined in the current crate can be \
+                             implemented for arbitrary types")
+                        .span_label(item.span, &format!("impl doesn't use types inside crate"))
+                        .note(&format!("the impl does not reference any \
+                                        types defined in this crate"))
+                        .emit();
                         return;
                     }
                     Err(traits::OrphanCheckErr::UncoveredTy(param_ty)) => {

src/librustc_typeck/collect.rs

@@ -367,8 +367,13 @@ impl<'a, 'tcx> AstConv<'tcx, 'tcx> for ItemCtxt<'a, 'tcx> {
                 _substs: Option<&mut Substs<'tcx>>,
                 _space: Option<ParamSpace>,
                 span: Span) -> Ty<'tcx> {
-        span_err!(self.tcx().sess, span, E0121,
-                  "the type placeholder `_` is not allowed within types on item signatures");
+        struct_span_err!(
+            self.tcx().sess,
+            span,
+            E0121,
+            "the type placeholder `_` is not allowed within types on item signatures"
+        ).span_label(span, &format!("not allowed in type signatures"))
+        .emit();
         self.tcx().types.err
     }
 
@@ -770,9 +775,10 @@ fn convert_item(ccx: &CrateCtxt, it: &hir::Item) {
                         let mut err = struct_span_err!(tcx.sess, impl_item.span, E0201,
                                                        "duplicate definitions with name `{}`:",
                                                        impl_item.name);
-                        span_note!(&mut err, *entry.get(),
-                                   "previous definition of `{}` here",
-                                   impl_item.name);
+                        err.span_label(*entry.get(),
+                                   &format!("previous definition of `{}` here",
+                                        impl_item.name));
+                        err.span_label(impl_item.span, &format!("duplicate definition"));
                         err.emit();
                     }
                     Vacant(entry) => {

src/librustc_typeck/lib.rs

@@ -211,11 +211,15 @@ fn check_main_fn_ty(ccx: &CrateCtxt,
             match tcx.map.find(main_id) {
                 Some(hir_map::NodeItem(it)) => {
                     match it.node {
-                        hir::ItemFn(_, _, _, _, ref ps, _)
-                        if ps.is_parameterized() => {
-                            span_err!(ccx.tcx.sess, main_span, E0131,
-                                      "main function is not allowed to have type parameters");
-                            return;
+                        hir::ItemFn(_, _, _, _, ref generics, _) => {
+                            if let Some(gen_span) = generics.span() {
+                                struct_span_err!(ccx.tcx.sess, gen_span, E0131,
+                                         "main function is not allowed to have type parameters")
+                                    .span_label(gen_span,
+                                                &format!("main cannot have type parameters"))
+                                    .emit();
+                                return;
+                            }
                         }
                         _ => ()
                     }

src/libstd/ffi/c_str.rs

@@ -373,6 +373,15 @@ impl NulError {
 
     /// Consumes this error, returning the underlying vector of bytes which
     /// generated the error in the first place.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::ffi::CString;
+    ///
+    /// let nul_error = CString::new("foo\0bar").unwrap_err();
+    /// assert_eq!(nul_error.into_vec(), b"foo\0bar");
+    /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn into_vec(self) -> Vec<u8> { self.1 }
 }