syntax: Implement #![no_core]

This commit is an implementation of [RFC 1184][rfc] which tweaks the behavior of
the `#![no_std]` attribute and adds a new `#![no_core]` attribute. The
`#![no_std]` attribute now injects `extern crate core` at the top of the crate
as well as the libcore prelude into all modules (in the same manner as the
standard library's prelude). The `#![no_core]` attribute disables both std and
core injection.

[rfc]: https://github.com/rust-lang/rfcs/pull/1184

30 files changed, 39 insertions, 8 deletions

diff --git a/src/libstd/sys/common/backtrace.rs b/src/libstd/sys/common/backtrace.rs
index 00932712a07..17953d0af4e 100644
--- a/src/libstd/sys/common/backtrace.rs
+++ b/src/libstd/sys/common/backtrace.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 use io::prelude::*;
 
diff --git a/src/libstd/sys/common/mod.rs b/src/libstd/sys/common/mod.rs
index 69c54f98917..b205b6df4cb 100644
--- a/src/libstd/sys/common/mod.rs
+++ b/src/libstd/sys/common/mod.rs
@@ -10,6 +10,7 @@
 
 #![allow(missing_docs)]
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 pub mod backtrace;
diff --git a/src/libstd/sys/common/poison.rs b/src/libstd/sys/common/poison.rs
index 065b1d6c9ac..196fe37d456 100644
--- a/src/libstd/sys/common/poison.rs
+++ b/src/libstd/sys/common/poison.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use cell::Cell;
diff --git a/src/libstd/sys/common/thread_info.rs b/src/libstd/sys/common/thread_info.rs
index bb47c946e49..fb4e0ec70e0 100644
--- a/src/libstd/sys/common/thread_info.rs
+++ b/src/libstd/sys/common/thread_info.rs
@@ -10,7 +10,8 @@
 
 #![allow(dead_code)] // stack_guard isn't used right now on all platforms
 
-use core::prelude::*;
+#[cfg(stage0)]
+use core::prelude::v1::*;
 
 use cell::RefCell;
 use string::String;
diff --git a/src/libstd/sys/common/thread_local.rs b/src/libstd/sys/common/thread_local.rs
index 3b2cb00d8c4..2269a053874 100644
--- a/src/libstd/sys/common/thread_local.rs
+++ b/src/libstd/sys/common/thread_local.rs
@@ -58,6 +58,7 @@
 #![unstable(feature = "thread_local_internals")]
 #![allow(dead_code)] // sys isn't exported yet
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use sync::atomic::{self, AtomicUsize, Ordering};
diff --git a/src/libstd/sys/common/wtf8.rs b/src/libstd/sys/common/wtf8.rs
index 3d5d1f5e0eb..0a5f4563dea 100644
--- a/src/libstd/sys/common/wtf8.rs
+++ b/src/libstd/sys/common/wtf8.rs
@@ -25,7 +25,8 @@
 // unix (it's mostly used on windows), so don't worry about dead code here.
 #![allow(dead_code)]
 
-use core::prelude::*;
+#[cfg(stage0)]
+use core::prelude::v1::*;
 
 use core::char::{encode_utf8_raw, encode_utf16_raw};
 use core::str::next_code_point;
diff --git a/src/libstd/sys/unix/backtrace.rs b/src/libstd/sys/unix/backtrace.rs
index ed6421f3670..ae8bfb07aaf 100644
--- a/src/libstd/sys/unix/backtrace.rs
+++ b/src/libstd/sys/unix/backtrace.rs
@@ -83,6 +83,7 @@
 /// to symbols. This is a bit of a hokey implementation as-is, but it works for
 /// all unix platforms we support right now, so it at least gets the job done.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 use io::prelude::*;
 
diff --git a/src/libstd/sys/unix/condvar.rs b/src/libstd/sys/unix/condvar.rs
index beecb445e8d..9dd8df7524d 100644
--- a/src/libstd/sys/unix/condvar.rs
+++ b/src/libstd/sys/unix/condvar.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use cell::UnsafeCell;
diff --git a/src/libstd/sys/unix/ext/fs.rs b/src/libstd/sys/unix/ext/fs.rs
index 4ee790b0161..dca7f6e829f 100644
--- a/src/libstd/sys/unix/ext/fs.rs
+++ b/src/libstd/sys/unix/ext/fs.rs
@@ -12,6 +12,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use fs::{self, Permissions, OpenOptions};
diff --git a/src/libstd/sys/unix/ext/process.rs b/src/libstd/sys/unix/ext/process.rs
index 63adae17581..71f83e7404b 100644
--- a/src/libstd/sys/unix/ext/process.rs
+++ b/src/libstd/sys/unix/ext/process.rs
@@ -14,6 +14,7 @@
 
 use os::unix::raw::{uid_t, gid_t};
 use os::unix::io::{FromRawFd, RawFd, AsRawFd, IntoRawFd};
+#[cfg(stage0)]
 use prelude::v1::*;
 use process;
 use sys;
diff --git a/src/libstd/sys/unix/fd.rs b/src/libstd/sys/unix/fd.rs
index 026380027d2..bdbe120f79d 100644
--- a/src/libstd/sys/unix/fd.rs
+++ b/src/libstd/sys/unix/fd.rs
@@ -8,7 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use core::prelude::*;
+#[cfg(stage0)]
+use core::prelude::v1::*;
 
 use io;
 use libc::{self, c_int, size_t, c_void};
diff --git a/src/libstd/sys/unix/fs.rs b/src/libstd/sys/unix/fs.rs
index 0c99a30f107..ddab24b133f 100644
--- a/src/libstd/sys/unix/fs.rs
+++ b/src/libstd/sys/unix/fs.rs
@@ -8,7 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use core::prelude::*;
+#[cfg(stage0)]
+use core::prelude::v1::*;
 use io::prelude::*;
 use os::unix::prelude::*;
 
diff --git a/src/libstd/sys/unix/mod.rs b/src/libstd/sys/unix/mod.rs
index 6fd20b940bb..85dc8752443 100644
--- a/src/libstd/sys/unix/mod.rs
+++ b/src/libstd/sys/unix/mod.rs
@@ -11,6 +11,7 @@
 #![allow(missing_docs)]
 #![allow(non_camel_case_types)]
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use io::{self, ErrorKind};
diff --git a/src/libstd/sys/unix/mutex.rs b/src/libstd/sys/unix/mutex.rs
index 6eed403dfc0..a6132b37a66 100644
--- a/src/libstd/sys/unix/mutex.rs
+++ b/src/libstd/sys/unix/mutex.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use cell::UnsafeCell;
diff --git a/src/libstd/sys/unix/os_str.rs b/src/libstd/sys/unix/os_str.rs
index 69d876a48a4..e21d88676e7 100644
--- a/src/libstd/sys/unix/os_str.rs
+++ b/src/libstd/sys/unix/os_str.rs
@@ -11,7 +11,8 @@
 /// The underlying OsString/OsStr implementation on Unix systems: just
 /// a `Vec<u8>`/`[u8]`.
 
-use core::prelude::*;
+#[cfg(stage0)]
+use core::prelude::v1::*;
 
 use borrow::Cow;
 use fmt::{self, Debug};
diff --git a/src/libstd/sys/unix/pipe.rs b/src/libstd/sys/unix/pipe.rs
index 140f0c042ba..2abd74bea1b 100644
--- a/src/libstd/sys/unix/pipe.rs
+++ b/src/libstd/sys/unix/pipe.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use sys::fd::FileDesc;
diff --git a/src/libstd/sys/unix/rwlock.rs b/src/libstd/sys/unix/rwlock.rs
index ee687f350f0..50b4907e6ca 100644
--- a/src/libstd/sys/unix/rwlock.rs
+++ b/src/libstd/sys/unix/rwlock.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use libc;
diff --git a/src/libstd/sys/unix/stack_overflow.rs b/src/libstd/sys/unix/stack_overflow.rs
index 62689c39255..ed4e50735a6 100644
--- a/src/libstd/sys/unix/stack_overflow.rs
+++ b/src/libstd/sys/unix/stack_overflow.rs
@@ -8,8 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
+use core::prelude::v1::*;
+
 use libc;
-use core::prelude::*;
 use self::imp::{make_handler, drop_handler};
 
 pub use self::imp::{init, cleanup};
diff --git a/src/libstd/sys/unix/stdio.rs b/src/libstd/sys/unix/stdio.rs
index fce52f8f92b..8542c660c26 100644
--- a/src/libstd/sys/unix/stdio.rs
+++ b/src/libstd/sys/unix/stdio.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use io;
diff --git a/src/libstd/sys/unix/thread_local.rs b/src/libstd/sys/unix/thread_local.rs
index 7238adfcc56..5626446b31c 100644
--- a/src/libstd/sys/unix/thread_local.rs
+++ b/src/libstd/sys/unix/thread_local.rs
@@ -10,6 +10,7 @@
 
 #![allow(dead_code)] // sys isn't exported yet
 
+#[cfg(stage0)]
 use prelude::v1::*;
 use libc::c_int;
 
diff --git a/src/libstd/sys/windows/backtrace.rs b/src/libstd/sys/windows/backtrace.rs
index 3f595762fc7..d84513c5f95 100644
--- a/src/libstd/sys/windows/backtrace.rs
+++ b/src/libstd/sys/windows/backtrace.rs
@@ -24,6 +24,7 @@
 
 #![allow(dead_code)]
 
+#[cfg(stage0)]
 use prelude::v1::*;
 use io::prelude::*;
 
diff --git a/src/libstd/sys/windows/condvar.rs b/src/libstd/sys/windows/condvar.rs
index 04d62200e9b..f3edcfd420c 100644
--- a/src/libstd/sys/windows/condvar.rs
+++ b/src/libstd/sys/windows/condvar.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use cell::UnsafeCell;
diff --git a/src/libstd/sys/windows/ext/fs.rs b/src/libstd/sys/windows/ext/fs.rs
index f629e983ce5..e15d1f0ec15 100644
--- a/src/libstd/sys/windows/ext/fs.rs
+++ b/src/libstd/sys/windows/ext/fs.rs
@@ -12,6 +12,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use fs::{OpenOptions, Metadata};
diff --git a/src/libstd/sys/windows/fs.rs b/src/libstd/sys/windows/fs.rs
index 4ce6d53cf12..8d81d6576ff 100644
--- a/src/libstd/sys/windows/fs.rs
+++ b/src/libstd/sys/windows/fs.rs
@@ -8,7 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use core::prelude::*;
+#[cfg(stage0)]
+use core::prelude::v1::*;
 use io::prelude::*;
 use os::windows::prelude::*;
 
diff --git a/src/libstd/sys/windows/handle.rs b/src/libstd/sys/windows/handle.rs
index a566c5eff32..91fe131c251 100644
--- a/src/libstd/sys/windows/handle.rs
+++ b/src/libstd/sys/windows/handle.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use io::ErrorKind;
diff --git a/src/libstd/sys/windows/net.rs b/src/libstd/sys/windows/net.rs
index d58355ed1fe..f2aca8d1a6e 100644
--- a/src/libstd/sys/windows/net.rs
+++ b/src/libstd/sys/windows/net.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use io;
diff --git a/src/libstd/sys/windows/pipe.rs b/src/libstd/sys/windows/pipe.rs
index a7ece66e0f1..4044c429d49 100644
--- a/src/libstd/sys/windows/pipe.rs
+++ b/src/libstd/sys/windows/pipe.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use io;
diff --git a/src/libstd/sys/windows/rwlock.rs b/src/libstd/sys/windows/rwlock.rs
index 25865286db0..010ffe76fba 100644
--- a/src/libstd/sys/windows/rwlock.rs
+++ b/src/libstd/sys/windows/rwlock.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use cell::UnsafeCell;
diff --git a/src/libstd/sys/windows/stack_overflow.rs b/src/libstd/sys/windows/stack_overflow.rs
index 491b53c4ed9..bc8ee6619f1 100644
--- a/src/libstd/sys/windows/stack_overflow.rs
+++ b/src/libstd/sys/windows/stack_overflow.rs
@@ -8,7 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use core::prelude::*;
+#[cfg(stage0)]
+use core::prelude::v1::*;
 
 use libc::types::os::arch::extra::{LPVOID, DWORD, LONG};
 use libc;
diff --git a/src/libstd/sys/windows/thread.rs b/src/libstd/sys/windows/thread.rs
index 42805c2ac52..a4131d4cada 100644
--- a/src/libstd/sys/windows/thread.rs
+++ b/src/libstd/sys/windows/thread.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#[cfg(stage0)]
 use prelude::v1::*;
 
 use alloc::boxed::FnBox;