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

34 files changed, 415 insertions, 357 deletions

diff --git a/src/test/codegen/function-arguments.rs b/src/test/codegen/function-arguments.rs
index bc84ac49da9..d8bbcd9b732 100644
--- a/src/test/codegen/function-arguments.rs
+++ b/src/test/codegen/function-arguments.rs
@@ -11,7 +11,7 @@
 // compile-flags: -C no-prepopulate-passes
 
 #![crate_type = "lib"]
-#![feature(allocator)]
+#![feature(custom_attribute)]
 
 pub struct S {
   _field: [i64; 4],
diff --git a/src/test/compile-fail/allocator-depends-on-needs-allocators.rs b/src/test/compile-fail/allocator-depends-on-needs-allocators.rs
deleted file mode 100644
index 7f420ff735a..00000000000
--- a/src/test/compile-fail/allocator-depends-on-needs-allocators.rs
+++ /dev/null
@@ -1,21 +0,0 @@
-// Copyright 2015 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.
-
-// error-pattern: `allocator3` cannot depend on a crate that needs an allocator
-// aux-build:needs_allocator.rs
-// aux-build:allocator3.rs
-
-// The needs_allocator crate is a dependency of the allocator crate allocator3,
-// which is not allowed
-
-extern crate allocator3;
-
-fn main() {
-}
diff --git a/src/test/compile-fail/allocator-dylib-is-system.rs b/src/test/compile-fail/allocator-dylib-is-system.rs
deleted file mode 100644
index 31009554c69..00000000000
--- a/src/test/compile-fail/allocator-dylib-is-system.rs
+++ /dev/null
@@ -1,41 +0,0 @@
-// Copyright 2015 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.
-
-// ignore-musl no dylibs
-// aux-build:allocator-dylib.rs
-// aux-build:allocator1.rs
-// no-prefer-dynamic
-// error-pattern: cannot link together two allocators
-
-// Verify that the allocator for statically linked dynamic libraries is the
-// system allocator. Do this by linking in jemalloc and making sure that we get
-// an error.
-
-// ignore-emscripten FIXME: What "other allocator" should we use for emcc?
-
-#![feature(alloc_jemalloc)]
-
-extern crate allocator_dylib;
-
-// The main purpose of this test is to ensure that `alloc_jemalloc` **fails**
-// here (specifically the jemalloc allocator), but currently jemalloc is
-// disabled on quite a few platforms (bsds, emscripten, msvc, etc). To ensure
-// that this just passes on those platforms we link in some other allocator to
-// ensure we get the same error.
-//
-// So long as we CI linux/macOS we should be good.
-#[cfg(any(target_os = "linux", target_os = "macos"))]
-extern crate alloc_jemalloc;
-#[cfg(not(any(target_os = "linux", target_os = "macos")))]
-extern crate allocator1;
-
-fn main() {
-    allocator_dylib::foo();
-}
diff --git a/src/test/compile-fail/allocator-rust-dylib-is-jemalloc.rs b/src/test/compile-fail/allocator-rust-dylib-is-jemalloc.rs
deleted file mode 100644
index 68e01bad96b..00000000000
--- a/src/test/compile-fail/allocator-rust-dylib-is-jemalloc.rs
+++ /dev/null
@@ -1,41 +0,0 @@
-// Copyright 2015 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.
-
-// ignore-musl no dylibs
-// aux-build:allocator-dylib2.rs
-// aux-build:allocator1.rs
-// error-pattern: cannot link together two allocators
-
-// Ensure that rust dynamic libraries use jemalloc as their allocator, verifying
-// by linking in the system allocator here and ensuring that we get a complaint.
-
-// ignore-emscripten FIXME: What "other allocator" is correct for emscripten?
-
-#![feature(alloc_system)]
-
-extern crate allocator_dylib2;
-
-// The main purpose of this test is to ensure that `alloc_system` **fails**
-// here (specifically the system allocator), but currently system is
-// disabled on quite a few platforms (bsds, emscripten, msvc, etc). To ensure
-// that this just passes on those platforms we link in some other allocator to
-// ensure we get the same error.
-//
-// So long as we CI linux/macOS we should be good.
-#[cfg(any(all(target_os = "linux", any(target_arch = "x86", target_arch = "x86_64")),
-          target_os = "macos"))]
-extern crate alloc_system;
-#[cfg(not(any(all(target_os = "linux", any(target_arch = "x86", target_arch = "x86_64")),
-              target_os = "macos")))]
-extern crate allocator1;
-
-fn main() {
-    allocator_dylib2::foo();
-}
diff --git a/src/test/compile-fail/auxiliary/allocator3.rs b/src/test/compile-fail/allocator/auxiliary/system-allocator.rs
index d3eb1f6f7ab..4761dc421d7 100644
--- a/src/test/compile-fail/auxiliary/allocator3.rs
+++ b/src/test/compile-fail/allocator/auxiliary/system-allocator.rs
@@ -1,4 +1,4 @@
-// Copyright 2015 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.
 //
@@ -10,10 +10,10 @@
 
 // no-prefer-dynamic
 
-#![feature(allocator)]
-#![no_std]
-#![allocator]
+#![feature(global_allocator, allocator_api)]
 #![crate_type = "rlib"]
 
-extern crate needs_allocator;
+use std::heap::System;
 
+#[global_allocator]
+static A: System = System;
diff --git a/src/test/compile-fail/auxiliary/allocator1.rs b/src/test/compile-fail/allocator/auxiliary/system-allocator2.rs
index b24784838d0..4761dc421d7 100644
--- a/src/test/compile-fail/auxiliary/allocator1.rs
+++ b/src/test/compile-fail/allocator/auxiliary/system-allocator2.rs
@@ -1,4 +1,4 @@
-// Copyright 2015 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.
 //
@@ -10,7 +10,10 @@
 
 // no-prefer-dynamic
 
-#![feature(allocator)]
-#![allocator]
+#![feature(global_allocator, allocator_api)]
 #![crate_type = "rlib"]
-#![no_std]
+
+use std::heap::System;
+
+#[global_allocator]
+static A: System = System;
diff --git a/src/test/compile-fail/allocator/function-allocator.rs b/src/test/compile-fail/allocator/function-allocator.rs
new file mode 100644
index 00000000000..50f82607b53
--- /dev/null
+++ b/src/test/compile-fail/allocator/function-allocator.rs
@@ -0,0 +1,16 @@
+// 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.
+//
+// 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.
+
+#![feature(global_allocator)]
+
+#[global_allocator]
+fn foo() {} //~ ERROR: allocators must be statics
+
+fn main() {}
diff --git a/src/test/compile-fail/allocator/not-an-allocator.rs b/src/test/compile-fail/allocator/not-an-allocator.rs
new file mode 100644
index 00000000000..e4301435063
--- /dev/null
+++ b/src/test/compile-fail/allocator/not-an-allocator.rs
@@ -0,0 +1,26 @@
+// 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.
+//
+// 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.
+
+#![feature(global_allocator, heap_api)]
+
+#[global_allocator]
+static A: usize = 0;
+//~^ the trait bound `&usize:
+//~| the trait bound `&usize:
+//~| the trait bound `&usize:
+//~| the trait bound `&usize:
+//~| the trait bound `&usize:
+//~| the trait bound `&usize:
+//~| the trait bound `&usize:
+//~| the trait bound `&usize:
+//~| the trait bound `&usize:
+//~| the trait bound `&usize:
+
+fn main() {}
diff --git a/src/test/compile-fail/two-allocators.rs b/src/test/compile-fail/allocator/two-allocators.rs
index a34f77de245..b46ba6334a2 100644
--- a/src/test/compile-fail/two-allocators.rs
+++ b/src/test/compile-fail/allocator/two-allocators.rs
@@ -1,4 +1,4 @@
-// Copyright 2015 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.
 //
@@ -8,12 +8,15 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// error-pattern: cannot link together two allocators
+#![feature(global_allocator, allocator_api)]
 
-// aux-build:allocator1.rs
-// aux-build:allocator2.rs
+use std::heap::System;
 
-extern crate allocator1;
-extern crate allocator2;
+#[global_allocator]
+static A: System = System;
+#[global_allocator]
+static B: System = System;
+//~^ ERROR: cannot define more than one #[global_allocator]
 
 fn main() {}
+
diff --git a/src/test/compile-fail/allocator/two-allocators2.rs b/src/test/compile-fail/allocator/two-allocators2.rs
new file mode 100644
index 00000000000..e342c1f9c44
--- /dev/null
+++ b/src/test/compile-fail/allocator/two-allocators2.rs
@@ -0,0 +1,25 @@
+// 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.
+//
+// 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.
+
+// aux-build:system-allocator.rs
+// no-prefer-dynamic
+// error-pattern: the #[global_allocator] in
+
+#![feature(global_allocator, allocator_api)]
+
+extern crate system_allocator;
+
+use std::heap::System;
+
+#[global_allocator]
+static A: System = System;
+
+fn main() {}
+
diff --git a/src/test/run-pass/allocator-system.rs b/src/test/compile-fail/allocator/two-allocators3.rs
index 4585003d579..c310d94f6df 100644
--- a/src/test/run-pass/allocator-system.rs
+++ b/src/test/compile-fail/allocator/two-allocators3.rs
@@ -1,4 +1,4 @@
-// Copyright 2015 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.
 //
@@ -8,12 +8,14 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// aux-build:system-allocator.rs
+// aux-build:system-allocator2.rs
 // no-prefer-dynamic
+// error-pattern: the #[global_allocator] in
 
-#![feature(alloc_system)]
+#![feature(global_allocator)]
 
-extern crate alloc_system;
+extern crate system_allocator;
+extern crate system_allocator2;
 
-fn main() {
-    println!("{:?}", Box::new(3));
-}
+fn main() {}
diff --git a/src/test/compile-fail/auxiliary/allocator-dylib.rs b/src/test/compile-fail/feature-gate-allocator_internals.rs
index 568b247ecdb..b519a985ec5 100644
--- a/src/test/compile-fail/auxiliary/allocator-dylib.rs
+++ b/src/test/compile-fail/feature-gate-allocator_internals.rs
@@ -1,4 +1,4 @@
-// Copyright 2015 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.
 //
@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// no-prefer-dynamic
+#![default_lib_allocator] //~ ERROR: attribute is an experimental feature
 
-#![crate_type = "dylib"]
+fn main() {}
 
-pub fn foo() {}
diff --git a/src/test/compile-fail/feature-gate-global_allocator.rs b/src/test/compile-fail/feature-gate-global_allocator.rs
new file mode 100644
index 00000000000..ff3c342f9e0
--- /dev/null
+++ b/src/test/compile-fail/feature-gate-global_allocator.rs
@@ -0,0 +1,14 @@
+// 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.
+//
+// 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.
+
+#[global_allocator] //~ ERROR: attribute is an experimental feature
+static A: usize = 0;
+
+fn main() {}
diff --git a/src/test/compile-fail/two-allocators-2.rs b/src/test/compile-fail/two-allocators-2.rs
deleted file mode 100644
index d6fcbcb513a..00000000000
--- a/src/test/compile-fail/two-allocators-2.rs
+++ /dev/null
@@ -1,21 +0,0 @@
-// Copyright 2015 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.
-
-// error-pattern: cannot link together two allocators: allocator1 and allocator2
-// aux-build:allocator1.rs
-// aux-build:allocator2.rs
-
-// Make sure we can't link together two explicit allocators.
-
-extern crate allocator1;
-extern crate allocator2;
-
-fn main() {}
-
diff --git a/src/test/compile-fail/two-allocators-3.rs b/src/test/compile-fail/two-allocators-3.rs
deleted file mode 100644
index 965e4e0e2ea..00000000000
--- a/src/test/compile-fail/two-allocators-3.rs
+++ /dev/null
@@ -1,23 +0,0 @@
-// Copyright 2015 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.
-
-// aux-build:allocator1.rs
-// error-pattern: cannot link together two allocators
-// ignore-musl no dylibs on musl yet
-// ignore-emscripten
-
-// We're linking std dynamically (via -C prefer-dynamic for this test) which
-// has an allocator and then we're also linking in a new allocator (allocator1)
-// and this should be an error
-
-extern crate allocator1;
-
-fn main() {
-}
diff --git a/src/test/run-make/no-duplicate-libs/Makefile b/src/test/run-make/no-duplicate-libs/Makefile
index 3f6a28c251a..13d8366c60a 100644
--- a/src/test/run-make/no-duplicate-libs/Makefile
+++ b/src/test/run-make/no-duplicate-libs/Makefile
@@ -4,9 +4,7 @@ ifdef IS_MSVC
 # FIXME(#27979)
 all:
 else
-all:
-	$(RUSTC) foo.rs
-	$(RUSTC) bar.rs
+all: $(call STATICLIB,foo) $(call STATICLIB,bar)
 	$(RUSTC) main.rs
 	$(call RUN,main)
 endif
diff --git a/src/test/compile-fail/feature-gate-allocator.rs b/src/test/run-make/no-duplicate-libs/bar.c
index 6490216d012..b9dcd0f5e5e 100644
--- a/src/test/compile-fail/feature-gate-allocator.rs
+++ b/src/test/run-make/no-duplicate-libs/bar.c
@@ -1,4 +1,4 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// 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.
 //
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![allocator] //~ ERROR: experimental feature
+extern void foo();
 
-fn main() {}
+void bar() {
+  foo();
+}
diff --git a/src/test/run-make/no-duplicate-libs/bar.rs b/src/test/run-make/no-duplicate-libs/bar.rs
deleted file mode 100644
index cb1c88689a8..00000000000
--- a/src/test/run-make/no-duplicate-libs/bar.rs
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2014 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.
-
-#![feature(lang_items, alloc_system, compiler_builtins_lib)]
-#![crate_type = "dylib"]
-#![no_std]
-
-extern crate alloc_system;
-extern crate compiler_builtins;
-
-#[no_mangle]
-pub extern fn bar() {}
-
-#[lang = "eh_personality"] fn eh_personality() {}
-#[lang = "eh_unwind_resume"] fn eh_unwind_resume() {}
-#[lang = "panic_fmt"] fn panic_fmt() -> ! { loop {} }
-#[no_mangle] pub extern fn rust_eh_register_frames () {}
-#[no_mangle] pub extern fn rust_eh_unregister_frames () {}
diff --git a/src/test/compile-fail/auxiliary/allocator-dylib2.rs b/src/test/run-make/no-duplicate-libs/foo.c
index 0d76c0e5eb8..906cd5682b8 100644
--- a/src/test/compile-fail/auxiliary/allocator-dylib2.rs
+++ b/src/test/run-make/no-duplicate-libs/foo.c
@@ -1,4 +1,4 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// 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.
 //
@@ -8,5 +8,4 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-pub fn foo() {}
-
+void foo() {}
diff --git a/src/test/run-make/no-duplicate-libs/foo.rs b/src/test/run-make/no-duplicate-libs/foo.rs
deleted file mode 100644
index 214fb156c2d..00000000000
--- a/src/test/run-make/no-duplicate-libs/foo.rs
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2014 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.
-
-#![feature(lang_items, alloc_system, compiler_builtins_lib)]
-#![no_std]
-#![crate_type = "dylib"]
-
-extern crate alloc_system;
-extern crate compiler_builtins;
-
-#[no_mangle]
-pub extern fn foo() {}
-
-#[lang = "eh_personality"] fn eh_personality() {}
-#[lang = "eh_unwind_resume"] fn eh_unwind_resume() {}
-#[lang = "panic_fmt"] fn panic_fmt() -> ! { loop {} }
-#[no_mangle] pub extern fn rust_eh_register_frames () {}
-#[no_mangle] pub extern fn rust_eh_unregister_frames () {}
diff --git a/src/test/run-make/no-duplicate-libs/main.rs b/src/test/run-make/no-duplicate-libs/main.rs
index 12ddce34582..824946fe9c2 100644
--- a/src/test/run-make/no-duplicate-libs/main.rs
+++ b/src/test/run-make/no-duplicate-libs/main.rs
@@ -8,9 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#[link(name = "foo")]
-#[link(name = "bar")]
-#[link(name = "foo")]
+#[link(name = "foo")] // linker should drop this library, no symbols used
+#[link(name = "bar")] // symbol comes from this library
+#[link(name = "foo")] // now linker picks up `foo` b/c `bar` library needs it
 extern {
     fn bar();
 }
diff --git a/src/test/run-pass/allocator-alloc-one.rs b/src/test/run-pass/allocator-alloc-one.rs
index 7cc547dcc04..712fa2d6001 100644
--- a/src/test/run-pass/allocator-alloc-one.rs
+++ b/src/test/run-pass/allocator-alloc-one.rs
@@ -8,20 +8,17 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![feature(alloc, allocator_api, heap_api, unique)]
+#![feature(allocator_api, unique)]
 
-extern crate alloc;
-
-use alloc::heap::HeapAlloc;
-use alloc::allocator::Alloc;
+use std::heap::{Heap, Alloc};
 
 fn main() {
     unsafe {
-        let ptr = HeapAlloc.alloc_one::<i32>().unwrap_or_else(|e| {
-            HeapAlloc.oom(e)
+        let ptr = Heap.alloc_one::<i32>().unwrap_or_else(|e| {
+            Heap.oom(e)
         });
         *ptr.as_ptr() = 4;
         assert_eq!(*ptr.as_ptr(), 4);
-        HeapAlloc.dealloc_one(ptr);
+        Heap.dealloc_one(ptr);
     }
 }
diff --git a/src/test/run-pass/allocator-default.rs b/src/test/run-pass/allocator-default.rs
deleted file mode 100644
index 0a02e8072b9..00000000000
--- a/src/test/run-pass/allocator-default.rs
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2015 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.
-
-#![feature(alloc_jemalloc)]
-
-#[cfg(any(all(target_os = "linux", any(target_arch = "x86", target_arch = "x86_64")),
-          target_os = "macos"))]
-extern crate alloc_jemalloc;
-
-fn main() {
-    println!("{:?}", Box::new(3));
-}
diff --git a/src/test/run-pass/allocator-override.rs b/src/test/run-pass/allocator-override.rs
deleted file mode 100644
index ca2dbdf2b3d..00000000000
--- a/src/test/run-pass/allocator-override.rs
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright 2015 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.
-
-// no-prefer-dynamic
-// aux-build:allocator-dummy.rs
-// ignore-emscripten
-
-#![feature(test)]
-
-extern crate allocator_dummy;
-extern crate test;
-
-fn main() {
-    unsafe {
-        let before = allocator_dummy::HITS;
-        let mut b = Box::new(3);
-        test::black_box(&mut b); // Make sure the allocation is not optimized away
-        assert_eq!(allocator_dummy::HITS - before, 1);
-        drop(b);
-        assert_eq!(allocator_dummy::HITS - before, 2);
-    }
-}
diff --git a/src/test/compile-fail/auxiliary/needs_allocator.rs b/src/test/run-pass/allocator/auxiliary/custom-as-global.rs
index 51003160427..538f36faadf 100644
--- a/src/test/compile-fail/auxiliary/needs_allocator.rs
+++ b/src/test/run-pass/allocator/auxiliary/custom-as-global.rs
@@ -1,4 +1,4 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// 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.
 //
@@ -10,7 +10,18 @@
 
 // no-prefer-dynamic
 
-#![feature(needs_allocator)]
-#![no_std]
-#![needs_allocator]
+#![feature(global_allocator)]
 #![crate_type = "rlib"]
+
+extern crate custom;
+
+use std::sync::atomic::{ATOMIC_USIZE_INIT, Ordering};
+
+use custom::A;
+
+#[global_allocator]
+static ALLOCATOR: A = A(ATOMIC_USIZE_INIT);
+
+pub fn get() -> usize {
+    ALLOCATOR.0.load(Ordering::SeqCst)
+}
diff --git a/src/test/run-pass/allocator/auxiliary/custom.rs b/src/test/run-pass/allocator/auxiliary/custom.rs
new file mode 100644
index 00000000000..8f4fbcd5ab1
--- /dev/null
+++ b/src/test/run-pass/allocator/auxiliary/custom.rs
@@ -0,0 +1,31 @@
+// 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.
+
+// no-prefer-dynamic
+
+#![feature(heap_api, allocator_api)]
+#![crate_type = "rlib"]
+
+use std::heap::{Alloc, System, AllocErr, Layout};
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+pub struct A(pub AtomicUsize);
+
+unsafe impl<'a> Alloc for &'a A {
+    unsafe fn alloc(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+        self.0.fetch_add(1, Ordering::SeqCst);
+        System.alloc(layout)
+    }
+
+    unsafe fn dealloc(&mut self, ptr: *mut u8, layout: Layout) {
+        self.0.fetch_add(1, Ordering::SeqCst);
+        System.dealloc(ptr, layout)
+    }
+}
diff --git a/src/test/compile-fail/auxiliary/allocator2.rs b/src/test/run-pass/allocator/auxiliary/helper.rs
index b24784838d0..e75a432710d 100644
--- a/src/test/compile-fail/auxiliary/allocator2.rs
+++ b/src/test/run-pass/allocator/auxiliary/helper.rs
@@ -1,4 +1,4 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// 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.
 //
@@ -10,7 +10,10 @@
 
 // no-prefer-dynamic
 
-#![feature(allocator)]
-#![allocator]
 #![crate_type = "rlib"]
-#![no_std]
+
+use std::fmt;
+
+pub fn work_with(p: &fmt::Debug) {
+    drop(p);
+}
diff --git a/src/test/run-pass/allocator/custom.rs b/src/test/run-pass/allocator/custom.rs
new file mode 100644
index 00000000000..b46f024b5bf
--- /dev/null
+++ b/src/test/run-pass/allocator/custom.rs
@@ -0,0 +1,68 @@
+// 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.
+
+// aux-build:helper.rs
+// no-prefer-dynamic
+
+#![feature(global_allocator, heap_api, allocator_api)]
+
+extern crate helper;
+
+use std::env;
+use std::heap::{Heap, Alloc, System, Layout, AllocErr};
+use std::sync::atomic::{AtomicUsize, Ordering, ATOMIC_USIZE_INIT};
+
+static HITS: AtomicUsize = ATOMIC_USIZE_INIT;
+
+struct A;
+
+unsafe impl<'a> Alloc for &'a A {
+    unsafe fn alloc(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+        HITS.fetch_add(1, Ordering::SeqCst);
+        System.alloc(layout)
+    }
+
+    unsafe fn dealloc(&mut self, ptr: *mut u8, layout: Layout) {
+        HITS.fetch_add(1, Ordering::SeqCst);
+        System.dealloc(ptr, layout)
+    }
+}
+
+#[global_allocator]
+static GLOBAL: A = A;
+
+fn main() {
+    env::set_var("FOO", "bar");
+    drop(env::var("FOO"));
+
+    let n = HITS.load(Ordering::SeqCst);
+    assert!(n > 0);
+    unsafe {
+        let layout = Layout::from_size_align(4, 2).unwrap();
+
+        let ptr = Heap.alloc(layout.clone()).unwrap();
+        helper::work_with(&ptr);
+        assert_eq!(HITS.load(Ordering::SeqCst), n + 1);
+        Heap.dealloc(ptr, layout.clone());
+        assert_eq!(HITS.load(Ordering::SeqCst), n + 2);
+
+        let s = String::with_capacity(10);
+        helper::work_with(&s);
+        assert_eq!(HITS.load(Ordering::SeqCst), n + 3);
+        drop(s);
+        assert_eq!(HITS.load(Ordering::SeqCst), n + 4);
+
+        let ptr = System.alloc(layout.clone()).unwrap();
+        assert_eq!(HITS.load(Ordering::SeqCst), n + 4);
+        helper::work_with(&ptr);
+        System.dealloc(ptr, layout);
+        assert_eq!(HITS.load(Ordering::SeqCst), n + 4);
+    }
+}
diff --git a/src/test/run-pass/allocator/xcrate-use.rs b/src/test/run-pass/allocator/xcrate-use.rs
new file mode 100644
index 00000000000..4b987b9223d
--- /dev/null
+++ b/src/test/run-pass/allocator/xcrate-use.rs
@@ -0,0 +1,44 @@
+// 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.
+
+// aux-build:custom.rs
+// aux-build:helper.rs
+// no-prefer-dynamic
+
+#![feature(global_allocator, heap_api, allocator_api)]
+
+extern crate custom;
+extern crate helper;
+
+use std::env;
+use std::heap::{Heap, Alloc, System, Layout};
+use std::sync::atomic::{Ordering, ATOMIC_USIZE_INIT};
+
+#[global_allocator]
+static GLOBAL: custom::A = custom::A(ATOMIC_USIZE_INIT);
+
+fn main() {
+    unsafe {
+        let n = GLOBAL.0.load(Ordering::SeqCst);
+        let layout = Layout::from_size_align(4, 2).unwrap();
+
+        let ptr = Heap.alloc(layout.clone()).unwrap();
+        helper::work_with(&ptr);
+        assert_eq!(GLOBAL.0.load(Ordering::SeqCst), n + 1);
+        Heap.dealloc(ptr, layout.clone());
+        assert_eq!(GLOBAL.0.load(Ordering::SeqCst), n + 2);
+
+        let ptr = System.alloc(layout.clone()).unwrap();
+        assert_eq!(GLOBAL.0.load(Ordering::SeqCst), n + 2);
+        helper::work_with(&ptr);
+        System.dealloc(ptr, layout);
+        assert_eq!(GLOBAL.0.load(Ordering::SeqCst), n + 2);
+    }
+}
diff --git a/src/test/run-pass/allocator/xcrate-use2.rs b/src/test/run-pass/allocator/xcrate-use2.rs
new file mode 100644
index 00000000000..7e6cd9fdf49
--- /dev/null
+++ b/src/test/run-pass/allocator/xcrate-use2.rs
@@ -0,0 +1,57 @@
+// 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.
+
+// aux-build:custom.rs
+// aux-build:custom-as-global.rs
+// aux-build:helper.rs
+// no-prefer-dynamic
+
+#![feature(heap_api, allocator_api)]
+
+extern crate custom;
+extern crate custom_as_global;
+extern crate helper;
+
+use std::env;
+use std::heap::{Heap, Alloc, System, Layout};
+use std::sync::atomic::{Ordering, ATOMIC_USIZE_INIT};
+
+static GLOBAL: custom::A = custom::A(ATOMIC_USIZE_INIT);
+
+fn main() {
+    unsafe {
+        let n = custom_as_global::get();
+        let layout = Layout::from_size_align(4, 2).unwrap();
+
+        // Global allocator routes to the `custom_as_global` global
+        let ptr = Heap.alloc(layout.clone()).unwrap();
+        helper::work_with(&ptr);
+        assert_eq!(custom_as_global::get(), n + 1);
+        Heap.dealloc(ptr, layout.clone());
+        assert_eq!(custom_as_global::get(), n + 2);
+
+        // Usage of the system allocator avoids all globals
+        let ptr = System.alloc(layout.clone()).unwrap();
+        helper::work_with(&ptr);
+        assert_eq!(custom_as_global::get(), n + 2);
+        System.dealloc(ptr, layout.clone());
+        assert_eq!(custom_as_global::get(), n + 2);
+
+        // Usage of our personal allocator doesn't affect other instances
+        let ptr = (&GLOBAL).alloc(layout.clone()).unwrap();
+        helper::work_with(&ptr);
+        assert_eq!(custom_as_global::get(), n + 2);
+        assert_eq!(GLOBAL.0.load(Ordering::SeqCst), 1);
+        (&GLOBAL).dealloc(ptr, layout);
+        assert_eq!(custom_as_global::get(), n + 2);
+        assert_eq!(GLOBAL.0.load(Ordering::SeqCst), 2);
+    }
+}
+
diff --git a/src/test/run-pass/lib-defaults.rs b/src/test/run-pass/lib-defaults.rs
index a38080f8cfe..6e5dccae0a0 100644
--- a/src/test/run-pass/lib-defaults.rs
+++ b/src/test/run-pass/lib-defaults.rs
@@ -8,16 +8,15 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// aux-build:clibrary.rs
-// compile-flags: -lclibrary
+// compile-flags: -lrust_test_helpers
 
-#[link(name = "clibrary", kind = "static")]
+#[link(name = "rust_test_helpers", kind = "static")]
 extern "C" {
-    pub fn foo(x:i32) -> i32;
+    pub fn rust_dbg_extern_identity_u32(x: u32) -> u32;
 }
 
 fn main() {
     unsafe {
-        foo(42);
+        rust_dbg_extern_identity_u32(42);
     }
 }
diff --git a/src/test/run-pass/realloc-16687.rs b/src/test/run-pass/realloc-16687.rs
index b32d42df6b1..eddcd5a584a 100644
--- a/src/test/run-pass/realloc-16687.rs
+++ b/src/test/run-pass/realloc-16687.rs
@@ -13,11 +13,9 @@
 // Ideally this would be revised to use no_std, but for now it serves
 // well enough to reproduce (and illustrate) the bug from #16687.
 
-#![feature(heap_api, alloc, oom)]
+#![feature(heap_api, allocator_api)]
 
-extern crate alloc;
-
-use alloc::heap;
+use std::heap::{Heap, Alloc, Layout};
 use std::ptr;
 
 fn main() {
@@ -47,38 +45,39 @@ unsafe fn test_triangle() -> bool {
 
     static PRINT : bool = false;
 
-    unsafe fn allocate(size: usize, align: usize) -> *mut u8 {
-        if PRINT { println!("allocate(size={} align={})", size, align); }
+    unsafe fn allocate(layout: Layout) -> *mut u8 {
+        if PRINT {
+            println!("allocate({:?})", layout);
+        }
 
-        let ret = heap::allocate(size, align);
-        if ret.is_null() { alloc::oom() }
+        let ret = Heap.alloc(layout.clone()).unwrap_or_else(|e| Heap.oom(e));
 
-        if PRINT { println!("allocate(size={} align={}) ret: 0x{:010x}",
-                            size, align, ret as usize);
+        if PRINT {
+            println!("allocate({:?}) = {:?}", layout, ret);
         }
 
         ret
     }
-    unsafe fn deallocate(ptr: *mut u8, size: usize, align: usize) {
-        if PRINT { println!("deallocate(ptr=0x{:010x} size={} align={})",
-                            ptr as usize, size, align);
+
+    unsafe fn deallocate(ptr: *mut u8, layout: Layout) {
+        if PRINT {
+            println!("deallocate({:?}, {:?}", ptr, layout);
         }
 
-        heap::deallocate(ptr, size, align);
+        Heap.dealloc(ptr, layout);
     }
-    unsafe fn reallocate(ptr: *mut u8, old_size: usize, size: usize, align: usize) -> *mut u8 {
+
+    unsafe fn reallocate(ptr: *mut u8, old: Layout, new: Layout) -> *mut u8 {
         if PRINT {
-            println!("reallocate(ptr=0x{:010x} old_size={} size={} align={})",
-                     ptr as usize, old_size, size, align);
+            println!("reallocate({:?}, old={:?}, new={:?})", ptr, old, new);
         }
 
-        let ret = heap::reallocate(ptr, old_size, size, align);
-        if ret.is_null() { alloc::oom() }
+        let ret = Heap.realloc(ptr, old.clone(), new.clone())
+            .unwrap_or_else(|e| Heap.oom(e));
 
         if PRINT {
-            println!("reallocate(ptr=0x{:010x} old_size={} size={} align={}) \
-                      ret: 0x{:010x}",
-                     ptr as usize, old_size, size, align, ret as usize);
+            println!("reallocate({:?}, old={:?}, new={:?}) = {:?}",
+                     ptr, old, new, ret);
         }
         ret
     }
@@ -91,8 +90,8 @@ unsafe fn test_triangle() -> bool {
     // way.)
     for i in 0..COUNT / 2 {
         let size = idx_to_size(i);
-        ascend[2*i]   = allocate(size, ALIGN);
-        ascend[2*i+1] = allocate(size, ALIGN);
+        ascend[2*i]   = allocate(Layout::from_size_align(size, ALIGN).unwrap());
+        ascend[2*i+1] = allocate(Layout::from_size_align(size, ALIGN).unwrap());
     }
 
     // Initialize each pair of rows to distinct value.
@@ -112,8 +111,8 @@ unsafe fn test_triangle() -> bool {
 
     for i in 0..COUNT / 2 {
         let size = idx_to_size(i);
-        deallocate(ascend[2*i], size, ALIGN);
-        deallocate(ascend[2*i+1], size, ALIGN);
+        deallocate(ascend[2*i], Layout::from_size_align(size, ALIGN).unwrap());
+        deallocate(ascend[2*i+1], Layout::from_size_align(size, ALIGN).unwrap());
     }
 
     return true;
@@ -124,14 +123,16 @@ unsafe fn test_triangle() -> bool {
     // rows as we go.
     unsafe fn test_1(ascend: &mut [*mut u8]) {
         let new_size = idx_to_size(COUNT-1);
+        let new = Layout::from_size_align(new_size, ALIGN).unwrap();
         for i in 0..COUNT / 2 {
             let (p0, p1, old_size) = (ascend[2*i], ascend[2*i+1], idx_to_size(i));
             assert!(old_size < new_size);
+            let old = Layout::from_size_align(old_size, ALIGN).unwrap();
 
-            ascend[2*i] = reallocate(p0, old_size, new_size, ALIGN);
+            ascend[2*i] = reallocate(p0, old.clone(), new.clone());
             sanity_check(&*ascend);
 
-            ascend[2*i+1] = reallocate(p1, old_size, new_size, ALIGN);
+            ascend[2*i+1] = reallocate(p1, old.clone(), new.clone());
             sanity_check(&*ascend);
         }
     }
@@ -139,14 +140,16 @@ unsafe fn test_triangle() -> bool {
     // Test 2: turn the square back into a triangle, top to bottom.
     unsafe fn test_2(ascend: &mut [*mut u8]) {
         let old_size = idx_to_size(COUNT-1);
+        let old = Layout::from_size_align(old_size, ALIGN).unwrap();
         for i in 0..COUNT / 2 {
             let (p0, p1, new_size) = (ascend[2*i], ascend[2*i+1], idx_to_size(i));
             assert!(new_size < old_size);
+            let new = Layout::from_size_align(new_size, ALIGN).unwrap();
 
-            ascend[2*i] = reallocate(p0, old_size, new_size, ALIGN);
+            ascend[2*i] = reallocate(p0, old.clone(), new.clone());
             sanity_check(&*ascend);
 
-            ascend[2*i+1] = reallocate(p1, old_size, new_size, ALIGN);
+            ascend[2*i+1] = reallocate(p1, old.clone(), new.clone());
             sanity_check(&*ascend);
         }
     }
@@ -154,14 +157,16 @@ unsafe fn test_triangle() -> bool {
     // Test 3: turn triangle into a square, bottom to top.
     unsafe fn test_3(ascend: &mut [*mut u8]) {
         let new_size = idx_to_size(COUNT-1);
+        let new = Layout::from_size_align(new_size, ALIGN).unwrap();
         for i in (0..COUNT / 2).rev() {
             let (p0, p1, old_size) = (ascend[2*i], ascend[2*i+1], idx_to_size(i));
             assert!(old_size < new_size);
+            let old = Layout::from_size_align(old_size, ALIGN).unwrap();
 
-            ascend[2*i+1] = reallocate(p1, old_size, new_size, ALIGN);
+            ascend[2*i+1] = reallocate(p1, old.clone(), new.clone());
             sanity_check(&*ascend);
 
-            ascend[2*i] = reallocate(p0, old_size, new_size, ALIGN);
+            ascend[2*i] = reallocate(p0, old.clone(), new.clone());
             sanity_check(&*ascend);
         }
     }
@@ -169,14 +174,16 @@ unsafe fn test_triangle() -> bool {
     // Test 4: turn the square back into a triangle, bottom to top.
     unsafe fn test_4(ascend: &mut [*mut u8]) {
         let old_size = idx_to_size(COUNT-1);
+        let old = Layout::from_size_align(old_size, ALIGN).unwrap();
         for i in (0..COUNT / 2).rev() {
             let (p0, p1, new_size) = (ascend[2*i], ascend[2*i+1], idx_to_size(i));
             assert!(new_size < old_size);
+            let new = Layout::from_size_align(new_size, ALIGN).unwrap();
 
-            ascend[2*i+1] = reallocate(p1, old_size, new_size, ALIGN);
+            ascend[2*i+1] = reallocate(p1, old.clone(), new.clone());
             sanity_check(&*ascend);
 
-            ascend[2*i] = reallocate(p0, old_size, new_size, ALIGN);
+            ascend[2*i] = reallocate(p0, old.clone(), new.clone());
             sanity_check(&*ascend);
         }
     }
diff --git a/src/test/run-pass/rfc1717/library-override.rs b/src/test/run-pass/rfc1717/library-override.rs
index d6ef96c5add..26713a25543 100644
--- a/src/test/run-pass/rfc1717/library-override.rs
+++ b/src/test/run-pass/rfc1717/library-override.rs
@@ -8,16 +8,15 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// aux-build:clibrary.rs
-// compile-flags: -lstatic=wronglibrary:clibrary
+// compile-flags: -lstatic=wronglibrary:rust_test_helpers
 
 #[link(name = "wronglibrary", kind = "dylib")]
 extern "C" {
-    pub fn foo(x:i32) -> i32;
+    pub fn rust_dbg_extern_identity_u32(x: u32) -> u32;
 }
 
 fn main() {
     unsafe {
-        foo(42);
+        rust_dbg_extern_identity_u32(42);
     }
 }
diff --git a/src/test/run-pass/smallest-hello-world.rs b/src/test/run-pass/smallest-hello-world.rs
index 053ee8ee42e..bcbd3fd3786 100644
--- a/src/test/run-pass/smallest-hello-world.rs
+++ b/src/test/run-pass/smallest-hello-world.rs
@@ -10,32 +10,32 @@
 
 // Smallest "hello world" with a libc runtime
 
-// pretty-expanded FIXME #23616
 // ignore-windows
+// ignore-android
 
 #![feature(intrinsics, lang_items, start, no_core, alloc_system)]
-#![no_core]
+#![feature(global_allocator, allocator_api)]
+#![no_std]
 
 extern crate alloc_system;
 
-extern { fn puts(s: *const u8); }
-extern "rust-intrinsic" { fn transmute<T, U>(t: T) -> U; }
+use alloc_system::System;
 
-#[lang = "eh_personality"] extern fn eh_personality() {}
-#[lang = "eh_unwind_resume"] extern fn eh_unwind_resume() {}
+#[global_allocator]
+static A: System = System;
+
+extern {
+    fn puts(s: *const u8);
+}
+
+#[no_mangle]
+#[lang = "eh_personality"] pub extern fn rust_eh_personality() {}
 #[lang = "panic_fmt"] fn panic_fmt() -> ! { loop {} }
-#[no_mangle] pub extern fn rust_eh_register_frames () {}
-#[no_mangle] pub extern fn rust_eh_unregister_frames () {}
 
 #[start]
 fn main(_: isize, _: *const *const u8) -> isize {
     unsafe {
-        let (ptr, _): (*const u8, usize) = transmute("Hello!\0");
-        puts(ptr);
+        puts("Hello!\0".as_ptr() as *const u8);
     }
-    return 0;
+    return 0
 }
-
-#[cfg(target_os = "android")]
-#[link(name="gcc")]
-extern { }