Auto merge of #36303 - jonathandturner:rollup, r=jonathandturner

Rollup of 8 pull requests

- Successful merges: #36121, #36128, #36241, #36243, #36263, #36267, #36273, #36298
- Failed merges:

Author: bors

CONTRIBUTING.md

@@ -151,6 +151,10 @@ Some common make targets are:
   command above as we only build the stage1 compiler, not the entire thing).
   You can also leave off the `-rpass` to run all stage1 test types.
 - `make check-stage1-coretest` - Run stage1 tests in `libcore`.
+- `make tidy` - Check that the source code is in compliance with Rust's style
+  guidelines. There is no official document describing Rust's full guidelines 
+  as of yet, but basic rules like 4 spaces for indentation and no more than 99
+  characters in a single line should be kept in mind when writing code.
 
 ## Pull Requests
 
@@ -177,6 +181,15 @@ you’re adding something to the standard library, try
 
 This will not rebuild the compiler, but will run the tests.
 
+Please make sure your pull request is in compliance with Rust's style
+guidelines by running
+
+    $ make tidy
+
+Make this check before every pull request (and every new commit in a pull
+request) ; you can add [git hooks](https://git-scm.com/book/en/v2/Customizing-Git-Git-Hooks)
+before every push to make sure you never forget to make this check.
+
 All pull requests are reviewed by another person. We have a bot,
 @rust-highfive, that will automatically assign a random person to review your
 request.

src/doc/nomicon/safe-unsafe-meaning.md

@@ -26,10 +26,6 @@ can therefore be trusted. You can use `unsafe` on a trait implementation
 to declare that the implementation of that trait has adhered to whatever
 contracts the trait's documentation requires.
 
-There is also the `#[unsafe_no_drop_flag]` attribute, which exists for
-historic reasons and is being phased out. See the section on [drop flags]
-for details.
-
 The standard library has a number of unsafe functions, including:
 
 * `slice::get_unchecked`, which performs unchecked indexing, allowing

src/doc/reference.md

@@ -2059,10 +2059,6 @@ macro scope.
   outside of its dynamic extent), and thus this attribute has the word
   "unsafe" in its name. To use this, the
   `unsafe_destructor_blind_to_params` feature gate must be enabled.
-- `unsafe_no_drop_flag` - on structs, remove the flag that prevents
-  destructors from being run twice. Destructors might be run multiple times on
-  the same object with this attribute. To use this, the `unsafe_no_drop_flag` feature
-  gate must be enabled.
 - `doc` - Doc comments such as `/// foo` are equivalent to `#[doc = "foo"]`.
 - `rustc_on_unimplemented` - Write a custom note to be shown along with the error
    when the trait is found to be unimplemented on a type.
@@ -2458,12 +2454,6 @@ The currently implemented features of the reference compiler are:
 * `unboxed_closures` - Rust's new closure design, which is currently a work in
                        progress feature with many known bugs.
 
-* `unsafe_no_drop_flag` - Allows use of the `#[unsafe_no_drop_flag]` attribute,
-                          which removes hidden flag added to a type that
-                          implements the `Drop` trait. The design for the
-                          `Drop` flag is subject to change, and this feature
-                          may be removed in the future.
-
 * `unmarked_api` - Allows use of items within a `#![staged_api]` crate
                    which have not been marked with a stability marker.
                    Such items should not be allowed by the compiler to exist,

src/libcollections/btree/map.rs

@@ -56,8 +56,12 @@ use self::Entry::*;
 /// however, performance is excellent.
 ///
 /// It is a logic error for a key to be modified in such a way that the key's ordering relative to
-/// any other key, as determined by the `Ord` trait, changes while it is in the map. This is
-/// normally only possible through `Cell`, `RefCell`, global state, I/O, or unsafe code.
+/// any other key, as determined by the [`Ord`] trait, changes while it is in the map. This is
+/// normally only possible through [`Cell`], [`RefCell`], global state, I/O, or unsafe code.
+///
+/// [`Ord`]: ../../std/cmp/trait.Ord.html
+/// [`Cell`]: ../../std/cell/struct.Cell.html
+/// [`RefCell`]: ../../std/cell/struct.RefCell.html
 ///
 /// # Examples
 ///
@@ -2020,7 +2024,7 @@ impl<'a, K: Ord, V> VacantEntry<'a, K, V> {
         self.key
     }
 
-    /// Sets the value of the entry with the VacantEntry's key,
+    /// Sets the value of the entry with the `VacantEntry`'s key,
     /// and returns a mutable reference to it.
     ///
     /// # Examples
@@ -2192,7 +2196,7 @@ impl<'a, K: Ord, V> OccupiedEntry<'a, K, V> {
         self.handle.into_kv_mut().1
     }
 
-    /// Sets the value of the entry with the OccupiedEntry's key,
+    /// Sets the value of the entry with the `OccupiedEntry`'s key,
     /// and returns the entry's old value.
     ///
     /// # Examples

src/librustc/hir/check_attr.rs

@@ -42,7 +42,9 @@ struct CheckAttrVisitor<'a> {
 impl<'a> CheckAttrVisitor<'a> {
     fn check_inline(&self, attr: &ast::Attribute, target: Target) {
         if target != Target::Fn {
-            span_err!(self.sess, attr.span, E0518, "attribute should be applied to function");
+            struct_span_err!(self.sess, attr.span, E0518, "attribute should be applied to function")
+                .span_label(attr.span, &format!("requires a function"))
+                .emit();
         }
     }
 
@@ -56,18 +58,20 @@ impl<'a> CheckAttrVisitor<'a> {
 
         let mut conflicting_reprs = 0;
         for word in words {
+
             let name = match word.name() {
                 Some(word) => word,
                 None => continue,
             };
 
-            let message = match &*name {
+            let (message, label) = match &*name {
                 "C" => {
                     conflicting_reprs += 1;
                     if target != Target::Struct &&
                             target != Target::Union &&
                             target != Target::Enum {
-                        "attribute should be applied to struct, enum or union"
+                                ("attribute should be applied to struct, enum or union",
+                                 "a struct, enum or union")
                     } else {
                         continue
                     }
@@ -77,15 +81,17 @@ impl<'a> CheckAttrVisitor<'a> {
                     // can be used to modify another repr hint
                     if target != Target::Struct &&
                             target != Target::Union {
-                        "attribute should be applied to struct or union"
+                                ("attribute should be applied to struct or union",
+                                 "a struct or union")
                     } else {
                         continue
                     }
                 }
                 "simd" => {
                     conflicting_reprs += 1;
                     if target != Target::Struct {
-                        "attribute should be applied to struct"
+                        ("attribute should be applied to struct",
+                         "a struct")
                     } else {
                         continue
                     }
@@ -95,15 +101,17 @@ impl<'a> CheckAttrVisitor<'a> {
                 "isize" | "usize" => {
                     conflicting_reprs += 1;
                     if target != Target::Enum {
-                        "attribute should be applied to enum"
+                        ("attribute should be applied to enum",
+                         "an enum")
                     } else {
                         continue
                     }
                 }
                 _ => continue,
             };
-
-            span_err!(self.sess, attr.span, E0517, "{}", message);
+            struct_span_err!(self.sess, attr.span, E0517, "{}", message)
+                .span_label(attr.span, &format!("requires {}", label))
+                .emit();
         }
         if conflicting_reprs > 1 {
             span_warn!(self.sess, attr.span, E0566,

src/librustc_typeck/astconv.rs

@@ -1769,8 +1769,11 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
                 }
             }
             hir::TyTypeof(ref _e) => {
-                span_err!(tcx.sess, ast_ty.span, E0516,
-                      "`typeof` is a reserved keyword but unimplemented");
+                struct_span_err!(tcx.sess, ast_ty.span, E0516,
+                                 "`typeof` is a reserved keyword but unimplemented")
+                    .span_label(ast_ty.span, &format!("reserved keyword"))
+                    .emit();
+
                 tcx.types.err
             }
             hir::TyInfer => {

src/librustc_typeck/check/_match.rs

@@ -233,9 +233,12 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                         let min_len = before.len() + after.len();
                         if slice.is_none() {
                             if min_len != size {
-                                span_err!(tcx.sess, pat.span, E0527,
-                                          "pattern requires {} elements but array has {}",
-                                          min_len, size);
+                                struct_span_err!(
+                                    tcx.sess, pat.span, E0527,
+                                    "pattern requires {} elements but array has {}",
+                                    min_len, size)
+                                    .span_label(pat.span, &format!("expected {} elements",size))
+                                    .emit();
                             }
                             (inner_ty, tcx.types.err)
                         } else if let Some(rest) = size.checked_sub(min_len) {

src/librustc_typeck/check/mod.rs

@@ -118,7 +118,6 @@ use syntax::parse::token::{self, InternedString, keywords};
 use syntax::ptr::P;
 use syntax::util::lev_distance::find_best_match_for_name;
 use syntax_pos::{self, Span};
-use errors::DiagnosticBuilder;
 
 use rustc::hir::intravisit::{self, Visitor};
 use rustc::hir::{self, PatKind};
@@ -2959,7 +2958,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             }, expr_t);
             match expr_t.sty {
                 ty::TyStruct(def, _) | ty::TyUnion(def, _) => {
-                    Self::suggest_field_names(&mut err, def.struct_variant(), field, vec![]);
+                    if let Some(suggested_field_name) =
+                        Self::suggest_field_name(def.struct_variant(), field, vec![]) {
+                        err.span_help(field.span,
+                                      &format!("did you mean `{}`?", suggested_field_name));
+                    };
                 }
                 ty::TyRawPtr(..) => {
                     err.note(&format!("`{0}` is a native pointer; perhaps you need to deref with \
@@ -2972,11 +2975,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         }
     }
 
-    // displays hints about the closest matches in field names
-    fn suggest_field_names(err: &mut DiagnosticBuilder,
-                           variant: ty::VariantDef<'tcx>,
-                           field: &Spanned<ast::Name>,
-                           skip : Vec<InternedString>) {
+    // Return an hint about the closest match in field names
+    fn suggest_field_name(variant: ty::VariantDef<'tcx>,
+                          field: &Spanned<ast::Name>,
+                          skip : Vec<InternedString>)
+                          -> Option<InternedString> {
         let name = field.node.as_str();
         let names = variant.fields.iter().filter_map(|field| {
             // ignore already set fields and private fields from non-local crates
@@ -2989,10 +2992,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         });
 
         // only find fits with at least one matching letter
-        if let Some(name) = find_best_match_for_name(names, &name, Some(name.len())) {
-            err.span_help(field.span,
-                          &format!("did you mean `{}`?", name));
-        }
+        find_best_match_for_name(names, &name, Some(name.len()))
     }
 
     // Check tuple index expressions
@@ -3086,7 +3086,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             ty);
         // prevent all specified fields from being suggested
         let skip_fields = skip_fields.iter().map(|ref x| x.name.node.as_str());
-        Self::suggest_field_names(&mut err, variant, &field.name, skip_fields.collect());
+        if let Some(field_name) = Self::suggest_field_name(variant,
+                                                           &field.name,
+                                                           skip_fields.collect()) {
+            err.span_label(field.name.span,&format!("did you mean `{}`?",field_name));
+        };
         err.emit();
     }