rustc: Implement the #[global_allocator] attribute

This PR is an implementation of [RFC 1974] which specifies a new method of
defining a global allocator for a program. This obsoletes the old
`#![allocator]` attribute and also removes support for it.

[RFC 1974]: https://github.com/rust-lang/rfcs/pull/197

The new `#[global_allocator]` attribute solves many issues encountered with the
`#![allocator]` attribute such as composition and restrictions on the crate
graph itself. The compiler now has much more control over the ABI of the
allocator and how it's implemented, allowing much more freedom in terms of how
this feature is implemented.

cc #27389

2 files changed, 0 insertions, 38 deletions

diff --git a/src/libstd/sys/unix/mod.rs b/src/libstd/sys/unix/mod.rs
index 854d380d128..46e5acdf3d2 100644
--- a/src/libstd/sys/unix/mod.rs
+++ b/src/libstd/sys/unix/mod.rs
@@ -59,8 +59,6 @@ pub mod stdio;
 
 #[cfg(not(test))]
 pub fn init() {
-    use alloc::oom;
-
     // By default, some platforms will send a *signal* when an EPIPE error
     // would otherwise be delivered. This runtime doesn't install a SIGPIPE
     // handler, causing it to kill the program, which isn't exactly what we
@@ -72,24 +70,6 @@ pub fn init() {
         reset_sigpipe();
     }
 
-    oom::set_oom_handler(oom_handler);
-
-    // A nicer handler for out-of-memory situations than the default one. This
-    // one prints a message to stderr before aborting. It is critical that this
-    // code does not allocate any memory since we are in an OOM situation. Any
-    // errors are ignored while printing since there's nothing we can do about
-    // them and we are about to exit anyways.
-    fn oom_handler() -> ! {
-        use intrinsics;
-        let msg = "fatal runtime error: out of memory\n";
-        unsafe {
-            libc::write(libc::STDERR_FILENO,
-                        msg.as_ptr() as *const libc::c_void,
-                        msg.len());
-            intrinsics::abort();
-        }
-    }
-
     #[cfg(not(any(target_os = "nacl", target_os = "emscripten", target_os="fuchsia")))]
     unsafe fn reset_sigpipe() {
         assert!(signal(libc::SIGPIPE, libc::SIG_IGN) != libc::SIG_ERR);
diff --git a/src/libstd/sys/windows/mod.rs b/src/libstd/sys/windows/mod.rs
index 840e7fdfc9b..ee58efc5144 100644
--- a/src/libstd/sys/windows/mod.rs
+++ b/src/libstd/sys/windows/mod.rs
@@ -47,24 +47,6 @@ pub mod stdio;
 
 #[cfg(not(test))]
 pub fn init() {
-    ::alloc::oom::set_oom_handler(oom_handler);
-
-    // See comment in sys/unix/mod.rs
-    fn oom_handler() -> ! {
-        use intrinsics;
-        use ptr;
-        let msg = "fatal runtime error: out of memory\n";
-        unsafe {
-            // WriteFile silently fails if it is passed an invalid handle, so
-            // there is no need to check the result of GetStdHandle.
-            c::WriteFile(c::GetStdHandle(c::STD_ERROR_HANDLE),
-                         msg.as_ptr() as c::LPVOID,
-                         msg.len() as c::DWORD,
-                         ptr::null_mut(),
-                         ptr::null_mut());
-            intrinsics::abort();
-        }
-    }
 }
 
 pub fn decode_error_kind(errno: i32) -> ErrorKind {