Auto merge of #46272 - kennytm:rollup, r=kennytm

Rollup of 7 pull requests

- Successful merges: #46201, #46224, #46234, #46252, #46259, #46264, #46269
- Failed merges:

README.md

@@ -129,6 +129,9 @@ CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.
 python x.py build
 ```
 
+If you are seeing build failure when compiling `rustc_binaryen`, make sure the path
+length of the rust folder is not longer than 22 characters.
+
 #### Specifying an ABI
 [specifying-an-abi]: #specifying-an-abi
 

src/liballoc/fmt.rs

@@ -236,6 +236,8 @@
 //! writeln!     // same as write but appends a newline
 //! print!       // the format string is printed to the standard output
 //! println!     // same as print but appends a newline
+//! eprint!      // the format string is printed to the standard error
+//! eprintln!    // same as eprint but appends a newline
 //! format_args! // described below.
 //! ```
 //!
@@ -264,6 +266,11 @@
 //! print!("Hello {}!", "world");
 //! println!("I have a newline {}", "character at the end");
 //! ```
+//! ### `eprint!`
+//!
+//! The [`eprint!`] and [`eprintln!`] macros are identical to
+//! [`print!`] and [`println!`], respectively, except they emit their
+//! output to stderr.
 //!
 //! ### `format_args!`
 //!
@@ -490,7 +497,10 @@
 //! [`writeln!`]: ../../std/macro.writeln.html
 //! [`write_fmt`]: ../../std/io/trait.Write.html#method.write_fmt
 //! [`std::io::Write`]: ../../std/io/trait.Write.html
+//! [`print!`]: ../../std/macro.print.html
 //! [`println!`]: ../../std/macro.println.html
+//! [`eprint!`]: ../../std/macro.eprint.html
+//! [`eprintln!`]: ../../std/macro.eprintln.html
 //! [`write!`]: ../../std/macro.write.html
 //! [`format_args!`]: ../../std/macro.format_args.html
 //! [`fmt::Arguments`]: struct.Arguments.html

src/liballoc/linked_list.rs

@@ -1288,6 +1288,8 @@ mod tests {
             let mut node_ptr: &Node<T>;
             match list.head {
                 None => {
+                    // tail node should also be None.
+                    assert!(list.tail.is_none());
                     assert_eq!(0, list.len);
                     return;
                 }
@@ -1314,6 +1316,11 @@ mod tests {
                     }
                 }
             }
+
+            // verify that the tail node points to the last node.
+            let tail = list.tail.as_ref().expect("some tail node").as_ref();
+            assert_eq!(tail as *const Node<T>, node_ptr as *const Node<T>);
+            // check that len matches interior links.
             assert_eq!(len, list.len);
         }
     }

src/libcore/marker.rs

@@ -314,7 +314,7 @@ pub trait Copy : Clone {
 ///
 /// For cases when one does need thread-safe interior mutability,
 /// Rust provides [atomic data types], as well as explicit locking via
-/// [`sync::Mutex`][mutex] and [`sync::RWLock`][rwlock]. These types
+/// [`sync::Mutex`][mutex] and [`sync::RwLock`][rwlock]. These types
 /// ensure that any mutation cannot cause data races, hence the types
 /// are `Sync`. Likewise, [`sync::Arc`][arc] provides a thread-safe
 /// analogue of [`Rc`][rc].

src/librustc/middle/lang_items.rs

@@ -40,7 +40,7 @@ macro_rules! language_item_table {
 
 
 enum_from_u32! {
-    #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
+    #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
     pub enum LangItem {
         $($variant,)*
     }

src/librustc_mir/transform/instcombine.rs

@@ -10,10 +10,10 @@
 
 //! Performs various peephole optimizations.
 
-use rustc::mir::{Location, Lvalue, Mir, Operand, ProjectionElem, Rvalue, Local};
+use rustc::mir::{Constant, Literal, Location, Lvalue, Mir, Operand, ProjectionElem, Rvalue, Local};
 use rustc::mir::visit::{MutVisitor, Visitor};
-use rustc::ty::TyCtxt;
-use rustc::util::nodemap::FxHashSet;
+use rustc::ty::{TyCtxt, TypeVariants};
+use rustc::util::nodemap::{FxHashMap, FxHashSet};
 use rustc_data_structures::indexed_vec::Idx;
 use std::mem;
 use transform::{MirPass, MirSource};
@@ -44,11 +44,11 @@ impl MirPass for InstCombine {
     }
 }
 
-pub struct InstCombineVisitor {
-    optimizations: OptimizationList,
+pub struct InstCombineVisitor<'tcx> {
+    optimizations: OptimizationList<'tcx>,
 }
 
-impl<'tcx> MutVisitor<'tcx> for InstCombineVisitor {
+impl<'tcx> MutVisitor<'tcx> for InstCombineVisitor<'tcx> {
     fn visit_rvalue(&mut self, rvalue: &mut Rvalue<'tcx>, location: Location) {
         if self.optimizations.and_stars.remove(&location) {
             debug!("Replacing `&*`: {:?}", rvalue);
@@ -62,6 +62,11 @@ impl<'tcx> MutVisitor<'tcx> for InstCombineVisitor {
             *rvalue = Rvalue::Use(Operand::Consume(new_lvalue))
         }
 
+        if let Some(constant) = self.optimizations.arrays_lengths.remove(&location) {
+            debug!("Replacing `Len([_; N])`: {:?}", rvalue);
+            *rvalue = Rvalue::Use(Operand::Constant(box constant));
+        }
+
         self.super_rvalue(rvalue, location)
     }
 }
@@ -70,7 +75,7 @@ impl<'tcx> MutVisitor<'tcx> for InstCombineVisitor {
 struct OptimizationFinder<'b, 'a, 'tcx:'a+'b> {
     mir: &'b Mir<'tcx>,
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
-    optimizations: OptimizationList,
+    optimizations: OptimizationList<'tcx>,
 }
 
 impl<'b, 'a, 'tcx:'b> OptimizationFinder<'b, 'a, 'tcx> {
@@ -93,11 +98,23 @@ impl<'b, 'a, 'tcx> Visitor<'tcx> for OptimizationFinder<'b, 'a, 'tcx> {
             }
         }
 
+        if let Rvalue::Len(ref lvalue) = *rvalue {
+            let lvalue_ty = lvalue.ty(&self.mir.local_decls, self.tcx).to_ty(self.tcx);
+            if let TypeVariants::TyArray(_, len) = lvalue_ty.sty {
+                let span = self.mir.source_info(location).span;
+                let ty = self.tcx.types.usize;
+                let literal = Literal::Value { value: len };
+                let constant = Constant { span, ty, literal };
+                self.optimizations.arrays_lengths.insert(location, constant);
+            }
+        }
+
         self.super_rvalue(rvalue, location)
     }
 }
 
 #[derive(Default)]
-struct OptimizationList {
+struct OptimizationList<'tcx> {
     and_stars: FxHashSet<Location>,
+    arrays_lengths: FxHashMap<Location, Constant<'tcx>>,
 }

src/libstd/io/mod.rs

@@ -441,7 +441,7 @@ fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize>
 /// # }
 /// ```
 ///
-/// Read from `&str` because [`&[u8]`] implements [`Read`]:
+/// Read from `&str` because [`&[u8]`] implements `Read`:
 ///
 /// ```
 /// # use std::io;
@@ -465,7 +465,6 @@ fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize>
 /// [`BufRead`]: trait.BufRead.html
 /// [`BufReader`]: struct.BufReader.html
 /// [`&[u8]`]: primitive.slice.html
-///
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(spotlight)]
 pub trait Read {

src/test/mir-opt/combine_array_len.rs

@@ -0,0 +1,33 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn norm2(x: [f32; 2]) -> f32 {
+    let a = x[0];
+    let b = x[1];
+    a*a + b*b
+}
+
+fn main() {
+    assert_eq!(norm2([3.0, 4.0]), 5.0*5.0);
+}
+
+// END RUST SOURCE
+
+// START rustc.norm2.InstCombine.before.mir
+//     _5 = Len(_1);
+//     ...
+//     _10 = Len(_1);
+// END rustc.norm2.InstCombine.before.mir
+
+// START rustc.norm2.InstCombine.after.mir
+//     _5 = const 2usize;
+//     ...
+//     _10 = const 2usize;
+// END rustc.norm2.InstCombine.after.mir