Add generic parameter for an allocator to collection types and box-like structures.

src/liballoc/alloc.rs

@@ -2,8 +2,13 @@
 
 #![stable(feature = "alloc_module", since = "1.28.0")]
 
-use core::intrinsics::{self, min_align_of_val, size_of_val};
-use core::ptr::{NonNull, Unique};
+#[cfg(not(test))]
+use core::intrinsics;
+#[cfg(not(test))]
+use core::ptr::NonNull;
+
+use core::intrinsics::{min_align_of_val, size_of_val};
+use core::ptr::Unique;
 
 #[stable(feature = "alloc_module", since = "1.28.0")]
 #[doc(inline)]
@@ -40,8 +45,12 @@ extern "Rust" {
 /// [`AllocRef`]: trait.AllocRef.html
 #[unstable(feature = "allocator_api", issue = "32838")]
 #[derive(Copy, Clone, Default, Debug)]
+#[cfg(not(test))]
 pub struct Global;
 
+#[cfg(test)]
+pub use std::alloc::Global;
+
 /// Allocate memory with the global allocator.
 ///
 /// This function forwards calls to the [`GlobalAlloc::alloc`] method
@@ -162,6 +171,7 @@ pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
 }
 
 #[unstable(feature = "allocator_api", issue = "32838")]
+#[cfg(not(test))]
 unsafe impl AllocRef for Global {
     #[inline]
     fn alloc(&mut self, layout: Layout, init: AllocInit) -> Result<MemoryBlock, AllocErr> {
@@ -278,11 +288,11 @@ unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
 // well.
 // For example if `Box` is changed to  `struct Box<T: ?Sized, A: AllocRef>(Unique<T>, A)`,
 // this function has to be changed to `fn box_free<T: ?Sized, A: AllocRef>(Unique<T>, A)` as well.
-pub(crate) unsafe fn box_free<T: ?Sized>(ptr: Unique<T>) {
+pub(crate) unsafe fn box_free<T: ?Sized, A: AllocRef>(ptr: Unique<T>, mut alloc: A) {
     let size = size_of_val(ptr.as_ref());
     let align = min_align_of_val(ptr.as_ref());
     let layout = Layout::from_size_align_unchecked(size, align);
-    Global.dealloc(ptr.cast().into(), layout)
+    alloc.dealloc(ptr.cast().into(), layout)
 }
 
 /// Abort on memory allocation error or failure.