Merge from rustc

2 files changed, 18 insertions, 2 deletions

diff --git a/src/tools/miri/tests/pass/address-reuse.rs b/src/tools/miri/tests/pass/address-reuse.rs
new file mode 100644
index 00000000000..9b5c8c38b8f
--- /dev/null
+++ b/src/tools/miri/tests/pass/address-reuse.rs
@@ -0,0 +1,16 @@
+//! Check that we do sometimes reuse addresses.
+use std::collections::HashSet;
+
+fn main() {
+    let count = 100;
+    let mut addrs = HashSet::<usize>::new();
+    for _ in 0..count {
+        // We make a `Box` with a layout that's hopefully not used by tons of things inside the
+        // allocator itself, so that we are more likely to get reuse. (With `i32` or `usize`, on
+        // Windows the reuse chances are very low.)
+        let b = Box::new([42usize; 4]);
+        addrs.insert(&*b as *const [usize; 4] as usize);
+    }
+    // dbg!(addrs.len());
+    assert!(addrs.len() > 1 && addrs.len() < count);
+}
diff --git a/src/tools/miri/tests/pass/intptrcast.rs b/src/tools/miri/tests/pass/intptrcast.rs
index 42b6f433420..370b09f512c 100644
--- a/src/tools/miri/tests/pass/intptrcast.rs
+++ b/src/tools/miri/tests/pass/intptrcast.rs
@@ -67,8 +67,8 @@ fn ptr_eq_dangling() {
     drop(b);
     let b = Box::new(0);
     let y = &*b as *const i32; // different allocation
-    // They *could* be equal if memory was reused, but probably are not.
-    assert!(x != y);
+    // They *could* be equal if memory is reused...
+    assert!(x != y || x == y);
 }
 
 fn ptr_eq_out_of_bounds() {