CTFE: support assert_zero_valid and assert_uninit_valid

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -394,10 +394,12 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
  sym::transmute => {
  self.copy_op_transmute(&args[0], dest)?;
  }
- sym::assert_inhabited => {
+ sym::assert_inhabited | sym::assert_zero_valid | sym::assert_uninit_valid => {
  let ty = instance.substs.type_at(0);
  let layout = self.layout_of(ty)?;
 
+ // For *all* intrinsics we first check `is_uninhabited` to give a more specific
+ // error message.
  if layout.abi.is_uninhabited() {
  // The run-time intrinsic panics just to get a good backtrace; here we abort
  // since there is no problem showing a backtrace even for aborts.
@@ -409,6 +411,28 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
  ),
  )?;
  }
+ if intrinsic_name == sym::assert_zero_valid
+ && !layout.might_permit_raw_init(self, /*zero:*/ true)
+ {
+ M::abort(
+ self,
+ format!(
+ "aborted execution: attempted to zero-initialize type `{}`, which is invalid",
+ ty
+ ),
+ )?;
+ }
+ if intrinsic_name == sym::assert_uninit_valid
+ && !layout.might_permit_raw_init(self, /*zero:*/ false)
+ {
+ M::abort(
+ self,
+ format!(
+ "aborted execution: attempted to leave type `{}` uninitialized, which is invalid",
+ ty
+ ),
+ )?;
+ }
  }
  sym::simd_insert => {
  let index = u64::from(self.read_scalar(&args[1])?.to_u32()?);

library/core/src/intrinsics.rs

@@ -860,12 +860,14 @@ extern "rust-intrinsic" {
  /// zero-initialization: This will statically either panic, or do nothing.
  ///
  /// This intrinsic does not have a stable counterpart.
+ #[rustc_const_unstable(feature = "const_assert_type2", issue = "none")]
  pub fn assert_zero_valid<T>();
 
  /// A guard for unsafe functions that cannot ever be executed if `T` has invalid
  /// bit patterns: This will statically either panic, or do nothing.
  ///
  /// This intrinsic does not have a stable counterpart.
+ #[rustc_const_unstable(feature = "const_assert_type2", issue = "none")]
  pub fn assert_uninit_valid<T>();
 
  /// Gets a reference to a static `Location` indicating where it was called.

src/test/ui/consts/assert-type-intrinsics.rs

@@ -0,0 +1,22 @@
+// error-pattern: any use of this value will cause an error
+
+#![feature(never_type)]
+#![feature(const_maybe_uninit_assume_init, const_assert_type2)]
+#![feature(core_intrinsics)]
+
+use std::intrinsics;
+
+#[allow(invalid_value)]
+fn main() {
+ use std::mem::MaybeUninit;
+
+ const _BAD1: () = unsafe {
+ MaybeUninit::<!>::uninit().assume_init();
+ };
+ const _BAD2: () = unsafe {
+ intrinsics::assert_uninit_valid::<bool>();
+ };
+ const _BAD3: () = unsafe {
+ intrinsics::assert_zero_valid::<&'static i32>();
+ };
+}

src/test/ui/consts/assert-type-intrinsics.stderr

@@ -0,0 +1,39 @@
+error: any use of this value will cause an error
+ --> $DIR/assert-type-intrinsics.rs:14:9
+ |
+LL | / const _BAD1: () = unsafe {
+LL | | MaybeUninit::<!>::uninit().assume_init();
+ | | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to instantiate uninhabited type `!`
+LL | | };
+ | |______-
+ |
+ = note: `#[deny(const_err)]` on by default
+ = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+ = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+error: any use of this value will cause an error
+ --> $DIR/assert-type-intrinsics.rs:17:9
+ |
+LL | / const _BAD2: () = unsafe {
+LL | | intrinsics::assert_uninit_valid::<bool>();
+ | | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to leave type `bool` uninitialized, which is invalid
+LL | | };
+ | |______-
+ |
+ = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+ = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+error: any use of this value will cause an error
+ --> $DIR/assert-type-intrinsics.rs:20:9
+ |
+LL | / const _BAD3: () = unsafe {
+LL | | intrinsics::assert_zero_valid::<&'static i32>();
+ | | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to zero-initialize type `&i32`, which is invalid
+LL | | };
+ | |______-
+ |
+ = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+ = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+error: aborting due to 3 previous errors
+