1 files changed, 17 insertions, 0 deletions
diff --git a/src/test/mir-opt/array_index_is_temporary.rs b/src/test/mir-opt/array_index_is_temporary.rs
new file mode 100644
index 000000000..e7bde81d4
--- /dev/null
+++ b/src/test/mir-opt/array_index_is_temporary.rs
@@ -0,0 +1,17 @@
+// Retagging (from Stacked Borrows) relies on the array index being a fresh
+// temporary, so that side-effects cannot change it.
+// Test that this is indeed the case.
+
+unsafe fn foo(z: *mut usize) -> u32 {
+    *z = 2;
+    99
+}
+
+
+// EMIT_MIR array_index_is_temporary.main.SimplifyCfg-elaborate-drops.after.mir
+fn main() {
+    let mut x = [42, 43, 44];
+    let mut y = 1;
+    let z: *mut usize = &mut y;
+    x[y] = unsafe { foo(z) };
+}