diff --git a/src/libcore/hint.rs b/src/libcore/hint.rs index 9ebcde79b633d..3116815f5d655 100644 --- a/src/libcore/hint.rs +++ b/src/libcore/hint.rs @@ -45,7 +45,8 @@ use crate::intrinsics; /// ``` #[inline] #[stable(feature = "unreachable", since = "1.27.0")] -pub unsafe fn unreachable_unchecked() -> ! { +#[rustc_const_unstable(feature = "const_unreachable_unchecked", issue = "53188")] +pub const unsafe fn unreachable_unchecked() -> ! { // SAFETY: the safety contract for `intrinsics::unreachable` must // be upheld by the caller. unsafe { intrinsics::unreachable() } diff --git a/src/libcore/intrinsics.rs b/src/libcore/intrinsics.rs index 080760aa81f30..8f0cf4361e708 100644 --- a/src/libcore/intrinsics.rs +++ b/src/libcore/intrinsics.rs @@ -932,6 +932,7 @@ extern "rust-intrinsic" { /// /// The stabilized version of this intrinsic is /// [`std::hint::unreachable_unchecked`](../../std/hint/fn.unreachable_unchecked.html). + #[rustc_const_unstable(feature = "const_unreachable_unchecked", issue = "53188")] pub fn unreachable() -> !; /// Informs the optimizer that a condition is always true. diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs index 96436bb253df0..a8c9b8f257700 100644 --- a/src/libcore/lib.rs +++ b/src/libcore/lib.rs @@ -91,6 +91,7 @@ #![feature(const_slice_ptr_len)] #![feature(const_type_name)] #![feature(const_likely)] +#![feature(const_unreachable_unchecked)] #![feature(custom_inner_attributes)] #![feature(decl_macro)] #![feature(doc_cfg)] diff --git a/src/librustc_mir/interpret/intrinsics.rs b/src/librustc_mir/interpret/intrinsics.rs index 851862640226f..5836fc9c95a80 100644 --- a/src/librustc_mir/interpret/intrinsics.rs +++ b/src/librustc_mir/interpret/intrinsics.rs @@ -95,6 +95,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { let (dest, ret) = match ret { None => match intrinsic_name { sym::transmute => throw_ub_format!("transmuting to uninhabited type"), + sym::unreachable => throw_ub!(Unreachable), sym::abort => M::abort(self)?, // Unsupported diverging intrinsic. _ => return Ok(false), diff --git a/src/test/ui/consts/const_unsafe_unreachable.rs b/src/test/ui/consts/const_unsafe_unreachable.rs new file mode 100644 index 0000000000000..cfed6e5deb999 --- /dev/null +++ b/src/test/ui/consts/const_unsafe_unreachable.rs @@ -0,0 +1,17 @@ +// run-pass + +#![feature(const_fn)] +#![feature(const_unreachable_unchecked)] + +const unsafe fn foo(x: bool) -> bool { + match x { + true => true, + false => std::hint::unreachable_unchecked(), + } +} + +const BAR: bool = unsafe { foo(true) }; + +fn main() { + assert_eq!(BAR, true); +} diff --git a/src/test/ui/consts/const_unsafe_unreachable_ub.rs b/src/test/ui/consts/const_unsafe_unreachable_ub.rs new file mode 100644 index 0000000000000..11920d852e02f --- /dev/null +++ b/src/test/ui/consts/const_unsafe_unreachable_ub.rs @@ -0,0 +1,20 @@ +// build-fail + +#![feature(const_fn)] +#![feature(const_unreachable_unchecked)] + +const unsafe fn foo(x: bool) -> bool { + match x { + true => true, + false => std::hint::unreachable_unchecked(), + } +} + +#[warn(const_err)] +const BAR: bool = unsafe { foo(false) }; + +fn main() { + assert_eq!(BAR, true); + //~^ ERROR E0080 + //~| ERROR erroneous constant +} diff --git a/src/test/ui/consts/const_unsafe_unreachable_ub.stderr b/src/test/ui/consts/const_unsafe_unreachable_ub.stderr new file mode 100644 index 0000000000000..3ef8043a54d88 --- /dev/null +++ b/src/test/ui/consts/const_unsafe_unreachable_ub.stderr @@ -0,0 +1,44 @@ +warning: any use of this value will cause an error + --> $SRC_DIR/libcore/hint.rs:LL:COL + | +LL | unsafe { intrinsics::unreachable() } + | ^^^^^^^^^^^^^^^^^^^^^^^^^ + | | + | entering unreachable code + | inside `std::hint::unreachable_unchecked` at $SRC_DIR/libcore/hint.rs:LL:COL + | inside `foo` at $DIR/const_unsafe_unreachable_ub.rs:9:18 + | inside `BAR` at $DIR/const_unsafe_unreachable_ub.rs:14:28 + | + ::: $DIR/const_unsafe_unreachable_ub.rs:14:1 + | +LL | const BAR: bool = unsafe { foo(false) }; + | ---------------------------------------- + | +note: the lint level is defined here + --> $DIR/const_unsafe_unreachable_ub.rs:13:8 + | +LL | #[warn(const_err)] + | ^^^^^^^^^ + +error[E0080]: evaluation of constant expression failed + --> $DIR/const_unsafe_unreachable_ub.rs:17:3 + | +LL | assert_eq!(BAR, true); + | ^^^^^^^^^^^---^^^^^^^^ + | | + | referenced constant has errors + | + = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info) + +error: erroneous constant used + --> $DIR/const_unsafe_unreachable_ub.rs:17:3 + | +LL | assert_eq!(BAR, true); + | ^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors + | + = note: `#[deny(const_err)]` on by default + = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info) + +error: aborting due to 2 previous errors; 1 warning emitted + +For more information about this error, try `rustc --explain E0080`.