From d24d408af387e99e7237f21e9a8d13a35552e01a Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Sun, 25 Jun 2017 11:33:47 -0700
Subject: [PATCH] std: Fix implementation of `Alloc::alloc_one`

This had an accidental `u8 as *mut T` where it was intended to have just a
normal pointer-to-pointer cast.

Closes #42827
---
 src/liballoc/allocator.rs                |  2 +-
 src/test/run-pass/allocator-alloc-one.rs | 27 ++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 src/test/run-pass/allocator-alloc-one.rs

diff --git a/src/liballoc/allocator.rs b/src/liballoc/allocator.rs
index 9bddce29957..bf38629ed38 100644
--- a/src/liballoc/allocator.rs
+++ b/src/liballoc/allocator.rs
@@ -873,7 +873,7 @@ fn alloc_one<T>(&mut self) -> Result<Unique<T>, AllocErr>
     {
         let k = Layout::new::<T>();
         if k.size() > 0 {
-            unsafe { self.alloc(k).map(|p|Unique::new(*p as *mut T)) }
+            unsafe { self.alloc(k).map(|p| Unique::new(p as *mut T)) }
         } else {
             Err(AllocErr::invalid_input("zero-sized type invalid for alloc_one"))
         }
diff --git a/src/test/run-pass/allocator-alloc-one.rs b/src/test/run-pass/allocator-alloc-one.rs
new file mode 100644
index 00000000000..7cc547dcc04
--- /dev/null
+++ b/src/test/run-pass/allocator-alloc-one.rs
@@ -0,0 +1,27 @@
+// 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.
+
+#![feature(alloc, allocator_api, heap_api, unique)]
+
+extern crate alloc;
+
+use alloc::heap::HeapAlloc;
+use alloc::allocator::Alloc;
+
+fn main() {
+    unsafe {
+        let ptr = HeapAlloc.alloc_one::<i32>().unwrap_or_else(|e| {
+            HeapAlloc.oom(e)
+        });
+        *ptr.as_ptr() = 4;
+        assert_eq!(*ptr.as_ptr(), 4);
+        HeapAlloc.dealloc_one(ptr);
+    }
+}