src/test/ui/consts/ptr_comparisons.rs

   1 // compile-flags: --crate-type=lib
   2 // normalize-stderr-32bit: "offset 8" -> "offset $$TWO_WORDS"
   3 // normalize-stderr-64bit: "offset 16" -> "offset $$TWO_WORDS"
   4 // normalize-stderr-32bit: "size 4" -> "size $$WORD"
   5 // normalize-stderr-64bit: "size 8" -> "size $$WORD"
   6
   7 #![feature(
   8     const_panic,
   9     core_intrinsics,
  10     const_raw_ptr_comparison,
  11     const_ptr_offset,
  12     const_raw_ptr_deref
  13 )]
  14
  15 const FOO: &usize = &42;
  16
  17 macro_rules! check {
  18     (eq, $a:expr, $b:expr) => {
  19         pub const _: () =
  20             assert!(std::intrinsics::ptr_guaranteed_eq($a as *const u8, $b as *const u8));
  21     };
  22     (ne, $a:expr, $b:expr) => {
  23         pub const _: () =
  24             assert!(std::intrinsics::ptr_guaranteed_ne($a as *const u8, $b as *const u8));
  25     };
  26     (!eq, $a:expr, $b:expr) => {
  27         pub const _: () =
  28             assert!(!std::intrinsics::ptr_guaranteed_eq($a as *const u8, $b as *const u8));
  29     };
  30     (!ne, $a:expr, $b:expr) => {
  31         pub const _: () =
  32             assert!(!std::intrinsics::ptr_guaranteed_ne($a as *const u8, $b as *const u8));
  33     };
  34 }
  35
  36 check!(eq, 0, 0);
  37 check!(ne, 0, 1);
  38 check!(!eq, 0, 1);
  39 check!(!ne, 0, 0);
  40 check!(ne, FOO as *const _, 0);
  41 check!(!eq, FOO as *const _, 0);
  42 // We want pointers to be equal to themselves, but aren't checking this yet because
  43 // there are some open questions (e.g. whether function pointers to the same function
  44 // compare equal, they don't necessarily at runtime).
  45 // The case tested here should work eventually, but does not work yet.
  46 check!(!eq, FOO as *const _, FOO as *const _);
  47 check!(ne, unsafe { (FOO as *const usize).offset(1) }, 0);
  48 check!(!eq, unsafe { (FOO as *const usize).offset(1) }, 0);
  49
  50 check!(ne, unsafe { (FOO as *const usize as *const u8).offset(3) }, 0);
  51 check!(!eq, unsafe { (FOO as *const usize as *const u8).offset(3) }, 0);
  52
  53 ///////////////////////////////////////////////////////////////////////////////
  54 // If any of the below start compiling, make sure to add a `check` test for it.
  55 // These invocations exist as canaries so we don't forget to check that the
  56 // behaviour of `guaranteed_eq` and `guaranteed_ne` is still correct.
  57 // All of these try to obtain an out of bounds pointer in some manner. If we
  58 // can create out of bounds pointers, we can offset a pointer far enough that
  59 // at runtime it would be zero and at compile-time it would not be zero.
  60
  61 const _: *const usize = unsafe { (FOO as *const usize).offset(2) };
  62 //~^ NOTE
  63
  64 const _: *const u8 =
  65 //~^ NOTE
  66     unsafe { std::ptr::addr_of!((*(FOO as *const usize as *const [u8; 1000]))[999]) };
  67 //~^ ERROR any use of this value will cause an error
  68 //~| NOTE
  69 //~| WARN this was previously accepted by the compiler but is being phased out
  70 //~| NOTE
  71
  72 const _: usize = unsafe { std::mem::transmute::<*const usize, usize>(FOO) + 4 };
  73 //~^ ERROR any use of this value will cause an error
  74 //~| NOTE cannot cast pointer to integer
  75 //~| NOTE
  76 //~| WARN this was previously accepted by the compiler but is being phased out
  77 //~| NOTE
  78
  79 const _: usize = unsafe { *std::mem::transmute::<&&usize, &usize>(&FOO) + 4 };
  80 //~^ ERROR any use of this value will cause an error
  81 //~| NOTE cannot cast pointer to integer
  82 //~| NOTE
  83 //~| WARN this was previously accepted by the compiler but is being phased out
  84 //~| NOTE