debug on AppVeyor

Author: RalfJung

.appveyor.yml

@@ -31,6 +31,7 @@ install:
 build_script:
     - set RUST_TEST_NOCAPTURE=1
     - set RUST_BACKTRACE=1
+    - set MIRI_BACKTRACE=1
     - set RUSTFLAGS=-C debug-assertions
     # Build and install miri
     - cargo build --release --all-features --all-targets

tests/run-pass/heap_allocator.rs

@@ -40,7 +40,8 @@ fn check_overalign_requests<T: Alloc>(mut allocator: T) {
             allocator.alloc(Layout::from_size_align(size, align).unwrap()).unwrap()
         }).collect();
         for &ptr in &pointers {
-            assert_eq!((ptr.as_ptr() as usize) % align, 0,
+            let ptr = ptr.as_ptr() as usize;
+            assert_eq!(ptr % align, 0,
                        "Got a pointer less aligned than requested")
         }