src/test/codegen/box-maybe-uninit.rs

   1 // compile-flags: -O
   2 #![crate_type="lib"]
   3
   4 use std::mem::MaybeUninit;
   5
   6 // Boxing a `MaybeUninit` value should not copy junk from the stack
   7 #[no_mangle]
   8 pub fn box_uninitialized() -> Box<MaybeUninit<usize>> {
   9     // CHECK-LABEL: @box_uninitialized
  10     // CHECK-NOT: store
  11     // CHECK-NOT: alloca
  12     // CHECK-NOT: memcpy
  13     // CHECK-NOT: memset
  14     Box::new(MaybeUninit::uninit())
  15 }
  16
  17 // FIXME: add a test for a bigger box. Currently broken, see
  18 // https://github.com/rust-lang/rust/issues/58201.