Rollup of 9 pull requests

src/liballoc/collections/btree/map.rs

@@ -196,7 +196,7 @@ impl<K: Clone, V: Clone> Clone for BTreeMap<K, V> {
                                 (root, length)
                             };
 
-                            out_node.push(k, v, subroot.unwrap_or_else(|| node::Root::new_leaf()));
+                            out_node.push(k, v, subroot.unwrap_or_else(node::Root::new_leaf));
                             out_tree.length += 1 + sublength;
                         }
                     }
@@ -2147,7 +2147,7 @@ impl<K, V> BTreeMap<K, V> {
     /// If the root node is the empty (non-allocated) root node, allocate our
     /// own node.
     fn ensure_root_is_owned(&mut self) -> &mut node::Root<K, V> {
-        self.root.get_or_insert_with(|| node::Root::new_leaf())
+        self.root.get_or_insert_with(node::Root::new_leaf)
     }
 }
 

src/liballoc/lib.rs

@@ -161,6 +161,8 @@ pub mod str;
 pub mod string;
 #[cfg(target_has_atomic = "ptr")]
 pub mod sync;
+#[cfg(target_has_atomic = "ptr")]
+pub mod task;
 #[cfg(test)]
 mod tests;
 pub mod vec;

src/liballoc/task.rs

@@ -0,0 +1,87 @@
+#![unstable(feature = "wake_trait", issue = "69912")]
+//! Types and Traits for working with asynchronous tasks.
+use core::mem::{self, ManuallyDrop};
+use core::task::{RawWaker, RawWakerVTable, Waker};
+
+use crate::sync::Arc;
+
+/// The implementation of waking a task on an executor.
+///
+/// This trait can be used to create a [`Waker`]. An executor can define an
+/// implementation of this trait, and use that to construct a Waker to pass
+/// to the tasks that are executed on that executor.
+///
+/// This trait is a memory-safe and ergonomic alternative to constructing a
+/// [`RawWaker`]. It supports the common executor design in which the data
+/// used to wake up a task is stored in an [`Arc`]. Some executors (especially
+/// those for embedded systems) cannot use this API, which is why [`RawWaker`]
+/// exists as an alternative for those systems.
+#[unstable(feature = "wake_trait", issue = "69912")]
+pub trait Wake {
+    /// Wake this task.
+    #[unstable(feature = "wake_trait", issue = "69912")]
+    fn wake(self: Arc<Self>);
+
+    /// Wake this task without consuming the waker.
+    ///
+    /// If an executor supports a cheaper way to wake without consuming the
+    /// waker, it should override this method. By default, it clones the
+    /// [`Arc`] and calls `wake` on the clone.
+    #[unstable(feature = "wake_trait", issue = "69912")]
+    fn wake_by_ref(self: &Arc<Self>) {
+        self.clone().wake();
+    }
+}
+
+#[unstable(feature = "wake_trait", issue = "69912")]
+impl<W: Wake + Send + Sync + 'static> From<Arc<W>> for Waker {
+    fn from(waker: Arc<W>) -> Waker {
+        // SAFETY: This is safe because raw_waker safely constructs
+        // a RawWaker from Arc<W>.
+        unsafe { Waker::from_raw(raw_waker(waker)) }
+    }
+}
+
+#[unstable(feature = "wake_trait", issue = "69912")]
+impl<W: Wake + Send + Sync + 'static> From<Arc<W>> for RawWaker {
+    fn from(waker: Arc<W>) -> RawWaker {
+        raw_waker(waker)
+    }
+}
+
+// NB: This private function for constructing a RawWaker is used, rather than
+// inlining this into the `From<Arc<W>> for RawWaker` impl, to ensure that
+// the safety of `From<Arc<W>> for Waker` does not depend on the correct
+// trait dispatch - instead both impls call this function directly and
+// explicitly.
+#[inline(always)]
+fn raw_waker<W: Wake + Send + Sync + 'static>(waker: Arc<W>) -> RawWaker {
+    // Increment the reference count of the arc to clone it.
+    unsafe fn clone_waker<W: Wake + Send + Sync + 'static>(waker: *const ()) -> RawWaker {
+        let waker: Arc<W> = Arc::from_raw(waker as *const W);
+        mem::forget(Arc::clone(&waker));
+        raw_waker(waker)
+    }
+
+    // Wake by value, moving the Arc into the Wake::wake function
+    unsafe fn wake<W: Wake + Send + Sync + 'static>(waker: *const ()) {
+        let waker: Arc<W> = Arc::from_raw(waker as *const W);
+        <W as Wake>::wake(waker);
+    }
+
+    // Wake by reference, wrap the waker in ManuallyDrop to avoid dropping it
+    unsafe fn wake_by_ref<W: Wake + Send + Sync + 'static>(waker: *const ()) {
+        let waker: ManuallyDrop<Arc<W>> = ManuallyDrop::new(Arc::from_raw(waker as *const W));
+        <W as Wake>::wake_by_ref(&waker);
+    }
+
+    // Decrement the reference count of the Arc on drop
+    unsafe fn drop_waker<W: Wake + Send + Sync + 'static>(waker: *const ()) {
+        mem::drop(Arc::from_raw(waker as *const W));
+    }
+
+    RawWaker::new(
+        Arc::into_raw(waker) as *const (),
+        &RawWakerVTable::new(clone_waker::<W>, wake::<W>, wake_by_ref::<W>, drop_waker::<W>),
+    )
+}

src/librustc/dep_graph/graph.rs

@@ -245,7 +245,7 @@ impl DepGraph {
         C: DepGraphSafe + StableHashingContextProvider<'a>,
     {
         if let Some(ref data) = self.data {
-            let task_deps = create_task(key).map(|deps| Lock::new(deps));
+            let task_deps = create_task(key).map(Lock::new);
 
             // In incremental mode, hash the result of the task. We don't
             // do anything with the hash yet, but we are computing it

src/librustc/lib.rs

@@ -38,6 +38,7 @@
 #![feature(extern_types)]
 #![feature(nll)]
 #![feature(option_expect_none)]
+#![feature(or_patterns)]
 #![feature(range_is_empty)]
 #![feature(specialization)]
 #![feature(trusted_len)]

src/librustc/mir/interpret/allocation.rs

@@ -796,7 +796,7 @@ impl UndefMask {
         }
 
         // FIXME(oli-obk): optimize this for allocations larger than a block.
-        let idx = (start.bytes()..end.bytes()).map(|i| Size::from_bytes(i)).find(|&i| !self.get(i));
+        let idx = (start.bytes()..end.bytes()).map(Size::from_bytes).find(|&i| !self.get(i));
 
         match idx {
             Some(idx) => Err(idx),

src/librustc/ty/mod.rs

@@ -35,7 +35,7 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::{self, par_iter, Lrc, ParallelIterator};
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Namespace, Res};
-use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX};
 use rustc_hir::{Constness, GlobMap, Node, TraitMap};
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_macros::HashStable;
@@ -2875,8 +2875,8 @@ impl<'tcx> TyCtxt<'tcx> {
                 _ => false,
             }
         } else {
-            match self.def_kind(def_id).expect("no def for `DefId`") {
-                DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy => true,
+            match self.def_kind(def_id) {
+                Some(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy) => true,
                 _ => false,
             }
         };
@@ -3054,17 +3054,7 @@ impl<'tcx> TyCtxt<'tcx> {
     /// If the given defid describes a method belonging to an impl, returns the
     /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
     pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
-        let item = if def_id.krate != LOCAL_CRATE {
-            if let Some(DefKind::AssocFn) = self.def_kind(def_id) {
-                Some(self.associated_item(def_id))
-            } else {
-                None
-            }
-        } else {
-            self.opt_associated_item(def_id)
-        };
-
-        item.and_then(|trait_item| match trait_item.container {
+        self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
             TraitContainer(_) => None,
             ImplContainer(def_id) => Some(def_id),
         })

src/librustc_ast/ast.rs

@@ -250,7 +250,7 @@ impl ParenthesizedArgs {
     pub fn as_angle_bracketed_args(&self) -> AngleBracketedArgs {
         AngleBracketedArgs {
             span: self.span,
-            args: self.inputs.iter().cloned().map(|input| GenericArg::Type(input)).collect(),
+            args: self.inputs.iter().cloned().map(GenericArg::Type).collect(),
             constraints: vec![],
         }
     }

src/librustc_ast_lowering/path.rs

@@ -272,7 +272,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         if !generic_args.parenthesized && !has_lifetimes {
             generic_args.args = self
                 .elided_path_lifetimes(path_span, expected_lifetimes)
-                .map(|lt| GenericArg::Lifetime(lt))
+                .map(GenericArg::Lifetime)
                 .chain(generic_args.args.into_iter())
                 .collect();
             if expected_lifetimes > 0 && param_mode == ParamMode::Explicit {

src/librustc_builtin_macros/deriving/generic/ty.rs

@@ -76,8 +76,8 @@ impl<'a> Path<'a> {
             self.params.iter().map(|t| t.to_ty(cx, span, self_ty, self_generics)).collect();
         let params = lt
             .into_iter()
-            .map(|lt| GenericArg::Lifetime(lt))
-            .chain(tys.into_iter().map(|ty| GenericArg::Type(ty)))
+            .map(GenericArg::Lifetime)
+            .chain(tys.into_iter().map(GenericArg::Type))
             .collect();
 
         match self.kind {

src/librustc_builtin_macros/source_util.rs

@@ -6,7 +6,7 @@ use rustc_ast_pretty::pprust;
 use rustc_expand::base::{self, *};
 use rustc_expand::module::DirectoryOwnership;
 use rustc_expand::panictry;
-use rustc_parse::{self, new_sub_parser_from_file, parser::Parser};
+use rustc_parse::{self, new_parser_from_file, parser::Parser};
 use rustc_session::lint::builtin::INCOMPLETE_INCLUDE;
 use rustc_span::symbol::Symbol;
 use rustc_span::{self, Pos, Span};
@@ -110,7 +110,7 @@ pub fn expand_include<'cx>(
             return DummyResult::any(sp);
         }
     };
-    let p = new_sub_parser_from_file(cx.parse_sess(), &file, None, sp);
+    let p = new_parser_from_file(cx.parse_sess(), &file, Some(sp));
 
     // If in the included file we have e.g., `mod bar;`,
     // then the path of `bar.rs` should be relative to the directory of `file`.

src/librustc_codegen_ssa/mir/constant.rs

@@ -40,31 +40,26 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         &mut self,
         constant: &mir::Constant<'tcx>,
     ) -> Result<ConstValue<'tcx>, ErrorHandled> {
-        match constant.literal.val {
-            ty::ConstKind::Unevaluated(def_id, substs, promoted) => {
-                let substs = self.monomorphize(&substs);
-                self.cx
-                    .tcx()
-                    .const_eval_resolve(ty::ParamEnv::reveal_all(), def_id, substs, promoted, None)
-                    .map_err(|err| {
-                        if promoted.is_none() {
-                            self.cx
-                                .tcx()
-                                .sess
-                                .span_err(constant.span, "erroneous constant encountered");
-                        }
-                        err
-                    })
-            }
+        match self.monomorphize(&constant.literal).val {
+            ty::ConstKind::Unevaluated(def_id, substs, promoted) => self
+                .cx
+                .tcx()
+                .const_eval_resolve(ty::ParamEnv::reveal_all(), def_id, substs, promoted, None)
+                .map_err(|err| {
+                    if promoted.is_none() {
+                        self.cx
+                            .tcx()
+                            .sess
+                            .span_err(constant.span, "erroneous constant encountered");
+                    }
+                    err
+                }),
             ty::ConstKind::Value(value) => Ok(value),
-            _ => {
-                let const_ = self.monomorphize(&constant.literal);
-                if let ty::ConstKind::Value(value) = const_.val {
-                    Ok(value)
-                } else {
-                    span_bug!(constant.span, "encountered bad ConstKind in codegen: {:?}", const_);
-                }
-            }
+            err => span_bug!(
+                constant.span,
+                "encountered bad ConstKind after monomorphizing: {:?}",
+                err
+            ),
         }
     }
 

src/librustc_data_structures/sharded.rs

@@ -30,7 +30,7 @@ pub struct Sharded<T> {
 impl<T: Default> Default for Sharded<T> {
     #[inline]
     fn default() -> Self {
-        Self::new(|| T::default())
+        Self::new(T::default)
     }
 }
 

src/librustc_error_codes/error_codes/E0449.md

@@ -1,5 +1,6 @@
-A visibility qualifier was used when it was unnecessary. Erroneous code
-examples:
+A visibility qualifier was used when it was unnecessary.
+
+Erroneous code examples:
 
 ```compile_fail,E0449
 struct Bar;

src/librustc_error_codes/error_codes/E0738.md

@@ -1,48 +1,11 @@
-`#[track_caller]` cannot be used in traits yet. This is due to limitations in
-the compiler which are likely to be temporary. See [RFC 2091] for details on
-this and other restrictions.
+`#[track_caller]` cannot be used to annotate foreign functions.
 
-Erroneous example with a trait method implementation:
+Erroneous example:
 
 ```compile_fail,E0738
 #![feature(track_caller)]
-
-trait Foo {
-    fn bar(&self);
-}
-
-impl Foo for u64 {
-    #[track_caller]
-    fn bar(&self) {}
-}
-```
-
-Erroneous example with a blanket trait method implementation:
-
-```compile_fail,E0738
-#![feature(track_caller)]
-
-trait Foo {
+extern "Rust" {
     #[track_caller]
-    fn bar(&self) {}
-    fn baz(&self);
+    fn bar();
 }
 ```
-
-Erroneous example with a trait method declaration:
-
-```compile_fail,E0738
-#![feature(track_caller)]
-
-trait Foo {
-    fn bar(&self) {}
-
-    #[track_caller]
-    fn baz(&self);
-}
-```
-
-Note that while the compiler may be able to support the attribute in traits in
-the future, [RFC 2091] prohibits their implementation without a follow-up RFC.
-
-[RFC 2091]: https://github.com/rust-lang/rfcs/blob/master/text/2091-inline-semantic.md

src/librustc_errors/diagnostic_builder.rs

@@ -162,7 +162,7 @@ impl<'a> DiagnosticBuilder<'a> {
         message: &str,
         span: Option<S>,
     ) -> &mut Self {
-        let span = span.map(|s| s.into()).unwrap_or_else(|| MultiSpan::new());
+        let span = span.map(|s| s.into()).unwrap_or_else(MultiSpan::new);
         self.0.diagnostic.sub(level, message, span, None);
         self
     }

src/librustc_expand/mbe/macro_rules.rs

@@ -259,8 +259,6 @@ fn generic_extension<'cx>(
                 }
 
                 let mut p = Parser::new(sess, tts, false, None);
-                p.root_module_name =
-                    cx.current_expansion.module.mod_path.last().map(|id| id.to_string());
                 p.last_type_ascription = cx.current_expansion.prior_type_ascription;
 
                 // Let the context choose how to interpret the result.

src/librustc_expand/module.rs

@@ -1,7 +1,7 @@
 use rustc_ast::ast::{self, Attribute, Ident, Mod};
 use rustc_ast::{attr, token};
 use rustc_errors::{struct_span_err, PResult};
-use rustc_parse::new_sub_parser_from_file;
+use rustc_parse::new_parser_from_file;
 use rustc_session::parse::ParseSess;
 use rustc_span::source_map::{FileName, Span};
 use rustc_span::symbol::sym;
@@ -59,9 +59,8 @@ crate fn parse_external_mod(
         *pop_mod_stack = true; // We have pushed, so notify caller.
         drop(included_mod_stack);
 
-        // Actually parse the external file as amodule.
-        let mut p0 = new_sub_parser_from_file(sess, &mp.path, Some(id.to_string()), span);
-        let mut module = p0.parse_mod(&token::Eof)?;
+        // Actually parse the external file as a module.
+        let mut module = new_parser_from_file(sess, &mp.path, Some(span)).parse_mod(&token::Eof)?;
         module.0.inline = false;
         module
     };

src/librustc_feature/lib.rs

@@ -51,7 +51,7 @@ pub struct Feature {
 
 impl Feature {
     fn issue(&self) -> Option<NonZeroU32> {
-        self.issue.and_then(|i| NonZeroU32::new(i))
+        self.issue.and_then(NonZeroU32::new)
     }
 }