Auto merge of #38466 - sanxiyn:rollup, r=sanxiyn

Rollup of 9 pull requests

- Successful merges: #38334, #38397, #38413, #38421, #38422, #38433, #38438, #38445, #38459
- Failed merges:

Author: bors

src/bootstrap/bin/rustc.rs

@@ -30,7 +30,7 @@ extern crate bootstrap;
 use std::env;
 use std::ffi::OsString;
 use std::path::PathBuf;
-use std::process::Command;
+use std::process::{Command, ExitStatus};
 
 fn main() {
     let args = env::args_os().skip(1).collect::<Vec<_>>();
@@ -180,8 +180,19 @@ fn main() {
     }
 
     // Actually run the compiler!
-    std::process::exit(match cmd.status() {
-        Ok(s) => s.code().unwrap_or(1),
+    std::process::exit(match exec_cmd(&mut cmd) {
+        Ok(s) => s.code().unwrap_or(0xfe),
         Err(e) => panic!("\n\nfailed to run {:?}: {}\n\n", cmd, e),
     })
 }
+
+#[cfg(unix)]
+fn exec_cmd(cmd: &mut Command) -> ::std::io::Result<ExitStatus> {
+    use std::os::unix::process::CommandExt;
+    Err(cmd.exec())
+}
+
+#[cfg(not(unix))]
+fn exec_cmd(cmd: &mut Command) -> ::std::io::Result<ExitStatus> {
+    cmd.status()
+}

src/libcore/hash/mod.rs

@@ -255,10 +255,44 @@ pub trait BuildHasher {
     fn build_hasher(&self) -> Self::Hasher;
 }
 
-/// A structure which implements `BuildHasher` for all `Hasher` types which also
-/// implement `Default`.
+/// The `BuildHasherDefault` structure is used in scenarios where one has a
+/// type that implements [`Hasher`] and [`Default`], but needs that type to
+/// implement [`BuildHasher`].
 ///
-/// This struct is 0-sized and does not need construction.
+/// This structure is zero-sized and does not need construction.
+///
+/// # Examples
+///
+/// Using `BuildHasherDefault` to specify a custom [`BuildHasher`] for
+/// [`HashMap`]:
+///
+/// ```
+/// use std::collections::HashMap;
+/// use std::hash::{BuildHasherDefault, Hasher};
+///
+/// #[derive(Default)]
+/// struct MyHasher;
+///
+/// impl Hasher for MyHasher {
+///     fn write(&mut self, bytes: &[u8]) {
+///         // Your hashing algorithm goes here!
+///        unimplemented!()
+///     }
+///
+///     fn finish(&self) -> u64 {
+///         // Your hashing algorithm goes here!
+///         unimplemented!()
+///     }
+/// }
+///
+/// type MyBuildHasher = BuildHasherDefault<MyHasher>;
+///
+/// let hash_map = HashMap::<u32, u32, MyBuildHasher>::default();
+/// ```
+///
+/// [`BuildHasher`]: trait.BuildHasher.html
+/// [`Default`]: ../default/trait.Default.html
+/// [`Hasher`]: trait.Hasher.html
 #[stable(since = "1.7.0", feature = "build_hasher")]
 pub struct BuildHasherDefault<H>(marker::PhantomData<H>);
 

src/librustc_back/target/aarch64_linux_android.rs

@@ -10,6 +10,9 @@
 
 use target::{Target, TargetOptions, TargetResult};
 
+// See https://developer.android.com/ndk/guides/abis.html#arm64-v8a
+// for target ABI requirements.
+
 pub fn target() -> TargetResult {
     let mut base = super::android_base::opts();
     base.max_atomic_width = Some(128);

src/librustc_back/target/armv7_linux_androideabi.rs

@@ -1,4 +1,4 @@
-// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -10,9 +10,12 @@
 
 use target::{Target, TargetOptions, TargetResult};
 
+// See https://developer.android.com/ndk/guides/abis.html#v7a
+// for target ABI requirements.
+
 pub fn target() -> TargetResult {
     let mut base = super::android_base::opts();
-    base.features = "+v7,+thumb2,+vfp3,+d16".to_string();
+    base.features = "+v7,+thumb2,+vfp3,+d16,-neon".to_string();
     base.max_atomic_width = Some(64);
 
     Ok(Target {

src/librustc_back/target/i686_linux_android.rs

@@ -10,6 +10,9 @@
 
 use target::{Target, TargetResult};
 
+// See https://developer.android.com/ndk/guides/abis.html#x86
+// for target ABI requirements.
+
 pub fn target() -> TargetResult {
     let mut base = super::android_base::opts();
 

src/libstd/process.rs

@@ -828,13 +828,30 @@ impl Child {
 /// this function at a known point where there are no more destructors left
 /// to run.
 ///
+/// ## Platform-specific behavior
+///
+/// **Unix**: On Unix-like platforms, it is unlikely that all 32 bits of `exit`
+/// will be visible to a parent process inspecting the exit code. On most
+/// Unix-like platforms, only the eight least-significant bits are considered.
+///
 /// # Examples
 ///
 /// ```
 /// use std::process;
 ///
 /// process::exit(0);
 /// ```
+///
+/// Due to [platform-specific behavior], the exit code for this example will be
+/// `0` on Linux, but `256` on Windows:
+///
+/// ```no_run
+/// use std::process;
+///
+/// process::exit(0x0f00);
+/// ```
+///
+/// [platform-specific behavior]: #platform-specific-behavior
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn exit(code: i32) -> ! {
     ::sys_common::cleanup();