Rollup of 6 pull requests

src/doc/unstable-book/src/SUMMARY.md

@@ -217,6 +217,7 @@
     - [unique](library-features/unique.md)
     - [unsize](library-features/unsize.md)
     - [utf8_error_error_len](library-features/utf8-error-error-len.md)
+    - [vec_resize_default](library-features/vec-resize-default.md)
     - [vec_remove_item](library-features/vec-remove-item.md)
     - [windows_c](library-features/windows-c.md)
     - [windows_handle](library-features/windows-handle.md)

src/doc/unstable-book/src/library-features/vec-resize-default.md

@@ -0,0 +1,7 @@
+# `vec_resize_default`
+
+The tracking issue for this feature is: [#41758]
+
+[#41758]: https://github.com/rust-lang/rust/issues/41758
+
+------------------------

src/libcollections/vec.rs

@@ -1220,11 +1220,14 @@ impl<T> Vec<T> {
 }
 
 impl<T: Clone> Vec<T> {
-    /// Resizes the `Vec` in-place so that `len()` is equal to `new_len`.
+    /// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
     ///
-    /// If `new_len` is greater than `len()`, the `Vec` is extended by the
+    /// If `new_len` is greater than `len`, the `Vec` is extended by the
     /// difference, with each additional slot filled with `value`.
-    /// If `new_len` is less than `len()`, the `Vec` is simply truncated.
+    /// If `new_len` is less than `len`, the `Vec` is simply truncated.
+    ///
+    /// This method requires `Clone` to clone the passed value. If you'd
+    /// rather create a value with `Default` instead, see [`resize_default`].
     ///
     /// # Examples
     ///
@@ -1237,19 +1240,100 @@ impl<T: Clone> Vec<T> {
     /// vec.resize(2, 0);
     /// assert_eq!(vec, [1, 2]);
     /// ```
+    ///
+    /// [`resize_default`]: #method.resize_default
     #[stable(feature = "vec_resize", since = "1.5.0")]
     pub fn resize(&mut self, new_len: usize, value: T) {
         let len = self.len();
 
         if new_len > len {
-            self.extend_with_element(new_len - len, value);
+            self.extend_with(new_len - len, ExtendElement(value))
+        } else {
+            self.truncate(new_len);
+        }
+    }
+
+    /// Clones and appends all elements in a slice to the `Vec`.
+    ///
+    /// Iterates over the slice `other`, clones each element, and then appends
+    /// it to this `Vec`. The `other` vector is traversed in-order.
+    ///
+    /// Note that this function is same as `extend` except that it is
+    /// specialized to work with slices instead. If and when Rust gets
+    /// specialization this function will likely be deprecated (but still
+    /// available).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec![1];
+    /// vec.extend_from_slice(&[2, 3, 4]);
+    /// assert_eq!(vec, [1, 2, 3, 4]);
+    /// ```
+    #[stable(feature = "vec_extend_from_slice", since = "1.6.0")]
+    pub fn extend_from_slice(&mut self, other: &[T]) {
+        self.spec_extend(other.iter())
+    }
+}
+
+impl<T: Default> Vec<T> {
+    /// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
+    ///
+    /// If `new_len` is greater than `len`, the `Vec` is extended by the
+    /// difference, with each additional slot filled with `Default::default()`.
+    /// If `new_len` is less than `len`, the `Vec` is simply truncated.
+    ///
+    /// This method uses `Default` to create new values on every push. If
+    /// you'd rather `Clone` a given value, use [`resize`].
+    ///
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(vec_resize_default)]
+    ///
+    /// let mut vec = vec![1, 2, 3];
+    /// vec.resize_default(5);
+    /// assert_eq!(vec, [1, 2, 3, 0, 0]);
+    ///
+    /// let mut vec = vec![1, 2, 3, 4];
+    /// vec.resize_default(2);
+    /// assert_eq!(vec, [1, 2]);
+    /// ```
+    ///
+    /// [`resize`]: #method.resize
+    #[unstable(feature = "vec_resize_default", issue = "41758")]
+    pub fn resize_default(&mut self, new_len: usize) {
+        let len = self.len();
+
+        if new_len > len {
+            self.extend_with(new_len - len, ExtendDefault);
         } else {
             self.truncate(new_len);
         }
     }
+}
 
-    /// Extend the vector by `n` additional clones of `value`.
-    fn extend_with_element(&mut self, n: usize, value: T) {
+// This code generalises `extend_with_{element,default}`.
+trait ExtendWith<T> {
+    fn next(&self) -> T;
+    fn last(self) -> T;
+}
+
+struct ExtendElement<T>(T);
+impl<T: Clone> ExtendWith<T> for ExtendElement<T> {
+    fn next(&self) -> T { self.0.clone() }
+    fn last(self) -> T { self.0 }
+}
+
+struct ExtendDefault;
+impl<T: Default> ExtendWith<T> for ExtendDefault {
+    fn next(&self) -> T { Default::default() }
+    fn last(self) -> T { Default::default() }
+}
+impl<T> Vec<T> {
+    /// Extend the vector by `n` values, using the given generator.
+    fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, value: E) {
         self.reserve(n);
 
         unsafe {
@@ -1261,43 +1345,21 @@ impl<T: Clone> Vec<T> {
 
             // Write all elements except the last one
             for _ in 1..n {
-                ptr::write(ptr, value.clone());
+                ptr::write(ptr, value.next());
                 ptr = ptr.offset(1);
-                // Increment the length in every step in case clone() panics
+                // Increment the length in every step in case next() panics
                 local_len.increment_len(1);
             }
 
             if n > 0 {
                 // We can write the last element directly without cloning needlessly
-                ptr::write(ptr, value);
+                ptr::write(ptr, value.last());
                 local_len.increment_len(1);
             }
 
             // len set by scope guard
         }
     }
-
-    /// Clones and appends all elements in a slice to the `Vec`.
-    ///
-    /// Iterates over the slice `other`, clones each element, and then appends
-    /// it to this `Vec`. The `other` vector is traversed in-order.
-    ///
-    /// Note that this function is same as `extend` except that it is
-    /// specialized to work with slices instead. If and when Rust gets
-    /// specialization this function will likely be deprecated (but still
-    /// available).
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// let mut vec = vec![1];
-    /// vec.extend_from_slice(&[2, 3, 4]);
-    /// assert_eq!(vec, [1, 2, 3, 4]);
-    /// ```
-    #[stable(feature = "vec_extend_from_slice", since = "1.6.0")]
-    pub fn extend_from_slice(&mut self, other: &[T]) {
-        self.spec_extend(other.iter())
-    }
 }
 
 // Set the length of the vec when the `SetLenOnDrop` value goes out of scope.
@@ -1389,7 +1451,7 @@ trait SpecFromElem: Sized {
 impl<T: Clone> SpecFromElem for T {
     default fn from_elem(elem: Self, n: usize) -> Vec<Self> {
         let mut v = Vec::with_capacity(n);
-        v.extend_with_element(n, elem);
+        v.extend_with(n, ExtendElement(elem));
         v
     }
 }
@@ -1424,7 +1486,7 @@ macro_rules! impl_spec_from_elem {
                     }
                 }
                 let mut v = Vec::with_capacity(n);
-                v.extend_with_element(n, elem);
+                v.extend_with(n, ExtendElement(elem));
                 v
             }
         }

src/libcore/num/wrapping.rs

@@ -12,6 +12,7 @@ use super::Wrapping;
 
 use ops::*;
 
+#[allow(unused_macros)]
 macro_rules! sh_impl_signed {
     ($t:ident, $f:ident) => (
         #[stable(feature = "rust1", since = "1.0.0")]

src/libcore/ops.rs

@@ -799,6 +799,7 @@ macro_rules! neg_impl_numeric {
     ($($t:ty)*) => { neg_impl_core!{ x => -x, $($t)*} }
 }
 
+#[allow(unused_macros)]
 macro_rules! neg_impl_unsigned {
     ($($t:ty)*) => {
         neg_impl_core!{ x => {

src/librustc/lint/builtin.rs

@@ -76,6 +76,12 @@ declare_lint! {
     "detects unreachable patterns"
 }
 
+declare_lint! {
+    pub UNUSED_MACROS,
+    Warn,
+    "detects macros that were not used"
+}
+
 declare_lint! {
     pub WARNINGS,
     Warn,
@@ -259,6 +265,7 @@ impl LintPass for HardwiredLints {
             DEAD_CODE,
             UNREACHABLE_CODE,
             UNREACHABLE_PATTERNS,
+            UNUSED_MACROS,
             WARNINGS,
             UNUSED_FEATURES,
             STABLE_FEATURES,

src/librustc/lint/context.rs

@@ -49,6 +49,7 @@ use hir;
 use hir::def_id::LOCAL_CRATE;
 use hir::intravisit as hir_visit;
 use syntax::visit as ast_visit;
+use syntax::tokenstream::ThinTokenStream;
 
 /// Information about the registered lints.
 ///
@@ -1125,6 +1126,13 @@ impl<'a> ast_visit::Visitor<'a> for EarlyContext<'a> {
     fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
         run_lints!(self, check_attribute, early_passes, attr);
     }
+
+    fn visit_mac_def(&mut self, _mac: &'a ThinTokenStream, id: ast::NodeId) {
+        let lints = self.sess.lints.borrow_mut().take(id);
+        for early_lint in lints {
+            self.early_lint(&early_lint);
+        }
+    }
 }
 
 enum CheckLintNameResult {

src/librustc_driver/driver.rs

@@ -699,6 +699,8 @@ pub fn phase_2_configure_and_expand<F>(sess: &Session,
 
         let krate = ecx.monotonic_expander().expand_crate(krate);
 
+        ecx.check_unused_macros();
+
         let mut missing_fragment_specifiers: Vec<_> =
             ecx.parse_sess.missing_fragment_specifiers.borrow().iter().cloned().collect();
         missing_fragment_specifiers.sort();

src/librustc_incremental/persist/preds/compress/test_macro.rs

@@ -37,14 +37,3 @@ macro_rules! graph {
         }
     }
 }
-
-macro_rules! set {
-    ($( $value:expr ),*) => {
-        {
-            use $crate::rustc_data_structures::fx::FxHashSet;
-            let mut set = FxHashSet();
-            $(set.insert($value);)*
-            set
-        }
-    }
-}

src/librustc_lint/lib.rs

@@ -171,7 +171,8 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
                     UNUSED_MUST_USE,
                     UNUSED_UNSAFE,
                     PATH_STATEMENTS,
-                    UNUSED_ATTRIBUTES);
+                    UNUSED_ATTRIBUTES,
+                    UNUSED_MACROS);
 
     // Guidelines for creating a future incompatibility lint:
     //

src/librustc_plugin/registry.rs

@@ -103,7 +103,8 @@ impl<'a> Registry<'a> {
         }
         self.syntax_exts.push((name, match extension {
             NormalTT(ext, _, allow_internal_unstable) => {
-                NormalTT(ext, Some(self.krate_span), allow_internal_unstable)
+                let nid = ast::CRATE_NODE_ID;
+                NormalTT(ext, Some((nid, self.krate_span)), allow_internal_unstable)
             }
             IdentTT(ext, _, allow_internal_unstable) => {
                 IdentTT(ext, Some(self.krate_span), allow_internal_unstable)

src/librustc_resolve/lib.rs

@@ -1187,6 +1187,10 @@ pub struct Resolver<'a> {
     pub whitelisted_legacy_custom_derives: Vec<Name>,
     pub found_unresolved_macro: bool,
 
+    // List of crate local macros that we need to warn about as being unused.
+    // Right now this only includes macro_rules! macros.
+    unused_macros: FxHashSet<DefId>,
+
     // Maps the `Mark` of an expansion to its containing module or block.
     invocations: FxHashMap<Mark, &'a InvocationData<'a>>,
 
@@ -1392,6 +1396,7 @@ impl<'a> Resolver<'a> {
             potentially_unused_imports: Vec::new(),
             struct_constructors: DefIdMap(),
             found_unresolved_macro: false,
+            unused_macros: FxHashSet(),
         }
     }
 

src/librustc_resolve/macros.rs

@@ -16,7 +16,7 @@ use resolve_imports::ImportResolver;
 use rustc::hir::def_id::{DefId, BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, DefIndex};
 use rustc::hir::def::{Def, Export};
 use rustc::hir::map::{self, DefCollector};
-use rustc::ty;
+use rustc::{ty, lint};
 use syntax::ast::{self, Name, Ident};
 use syntax::attr::{self, HasAttrs};
 use syntax::errors::DiagnosticBuilder;
@@ -291,12 +291,32 @@ impl<'a> base::Resolver for Resolver<'a> {
             },
         };
         self.macro_defs.insert(invoc.expansion_data.mark, def.def_id());
+        self.unused_macros.remove(&def.def_id());
         Ok(Some(self.get_macro(def)))
     }
 
     fn resolve_macro(&mut self, scope: Mark, path: &ast::Path, kind: MacroKind, force: bool)
                      -> Result<Rc<SyntaxExtension>, Determinacy> {
-        self.resolve_macro_to_def(scope, path, kind, force).map(|def| self.get_macro(def))
+        self.resolve_macro_to_def(scope, path, kind, force).map(|def| {
+            self.unused_macros.remove(&def.def_id());
+            self.get_macro(def)
+        })
+    }
+
+    fn check_unused_macros(&self) {
+        for did in self.unused_macros.iter() {
+            let id_span = match *self.macro_map[did] {
+                SyntaxExtension::NormalTT(_, isp, _) => isp,
+                _ => None,
+            };
+            if let Some((id, span)) = id_span {
+                let lint = lint::builtin::UNUSED_MACROS;
+                let msg = "unused macro definition".to_string();
+                self.session.add_lint(lint, id, span, msg);
+            } else {
+                bug!("attempted to create unused macro error, but span not available");
+            }
+        }
     }
 }
 
@@ -687,6 +707,8 @@ impl<'a> Resolver<'a> {
         if attr::contains_name(&item.attrs, "macro_export") {
             let def = Def::Macro(def_id, MacroKind::Bang);
             self.macro_exports.push(Export { name: ident.name, def: def, span: item.span });
+        } else {
+            self.unused_macros.insert(def_id);
         }
     }
 

src/librustc_typeck/check/method/suggest.rs

@@ -251,9 +251,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                     let bound_list = unsatisfied_predicates.iter()
                         .map(|p| format!("`{} : {}`", p.self_ty(), p))
                         .collect::<Vec<_>>()
-                        .join(", ");
+                        .join("\n");
                     err.note(&format!("the method `{}` exists but the following trait bounds \
-                                       were not satisfied: {}",
+                                       were not satisfied:\n{}",
                                       item_name,
                                       bound_list));
                 }