improve test

Author: beepster4096

tests/run-pass/global_allocator.rs

@@ -1,29 +1,15 @@
-use std::alloc::{GlobalAlloc, Layout, System};
+#![feature(allocator_api, slice_ptr_get)]
 
-#[global_allocator]
-static ALLOCATOR: Allocator = Allocator;
-
-struct Allocator;
-
-unsafe impl GlobalAlloc for Allocator {
-    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
-        // use specific size to avoid getting triggered by rt
-        if layout.size() == 123 {
-            println!("Allocated!")
-        }
-
-        System.alloc(layout)
-    }
+use std::alloc::{Allocator, Global, Layout, System};
 
-    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
-        if layout.size() == 123 {
-            println!("Dellocated!")
-        }
-
-        System.dealloc(ptr, layout)
-    }
-}
+#[global_allocator]
+static ALLOCATOR: System = System;
 
 fn main() {
-    Box::new([0_u8; 123]);
+    // Only okay because we explicitly set the system allocator as the global one!
+    let l = Layout::from_size_align(1, 1).unwrap();
+    let ptr = Global.allocate(l).unwrap().as_non_null_ptr(); // allocating with Global...
+    unsafe {
+        System.deallocate(ptr, l);
+    } // ... and deallocating with System.
 }