std: Delete the alloc_system crate

This commit deletes the `alloc_system` crate from the standard
distribution. This unstable crate is no longer needed in the modern
stable global allocator world, but rather its functionality is folded
directly into the standard library. The standard library was already the
only stable location to access this crate, and as a result this should
not affect any stable code.

Author: alexcrichton

src/Cargo.lock

@@ -15,16 +15,6 @@ dependencies = [
  "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "alloc_system"
-version = "0.0.0"
-dependencies = [
- "compiler_builtins 0.0.0",
- "core 0.0.0",
- "dlmalloc 0.0.0",
- "libc 0.0.0",
-]
-
 [[package]]
 name = "ammonia"
 version = "1.1.0"
@@ -2104,7 +2094,6 @@ name = "rustc_asan"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
- "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "compiler_builtins 0.0.0",
@@ -2276,7 +2265,6 @@ name = "rustc_lsan"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
- "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "compiler_builtins 0.0.0",
@@ -2328,7 +2316,6 @@ name = "rustc_msan"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
- "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "compiler_builtins 0.0.0",
@@ -2440,7 +2427,6 @@ name = "rustc_tsan"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
- "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "compiler_builtins 0.0.0",
@@ -2679,11 +2665,11 @@ name = "std"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
- "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cc 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
  "compiler_builtins 0.0.0",
  "core 0.0.0",
+ "dlmalloc 0.0.0",
  "libc 0.0.0",
  "panic_abort 0.0.0",
  "panic_unwind 0.0.0",

src/bootstrap/dist.rs

@@ -859,7 +859,6 @@ impl Step for Src {
             "src/build_helper",
             "src/dlmalloc",
             "src/liballoc",
-            "src/liballoc_system",
             "src/libbacktrace",
             "src/libcompiler_builtins",
             "src/libcore",

src/ci/docker/wasm32-unknown/Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:16.04
+FROM ubuntu:18.04
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
   g++ \

src/liballoc/tests/heap.rs

@@ -8,8 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use alloc_system::System;
-use std::alloc::{Global, Alloc, Layout};
+use std::alloc::{Global, Alloc, Layout, System};
 
 /// https://github.com/rust-lang/rust/issues/45955
 #[test]

src/liballoc/tests/lib.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 #![feature(allocator_api)]
-#![feature(alloc_system)]
 #![feature(box_syntax)]
 #![feature(drain_filter)]
 #![feature(exact_size_is_empty)]
@@ -20,7 +19,6 @@
 #![feature(unboxed_closures)]
 #![feature(repeat_generic_slice)]
 
-extern crate alloc_system;
 extern crate core;
 extern crate rand;