Rustup to rustc 1.62.0-nightly (879aff385 2022-04-20)

build_sysroot/Cargo.lock

@@ -134,9 +134,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.121"
+version = "0.2.124"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "efaa7b300f3b5fe8eb6bf21ce3895e1751d9665086af2d64b42f19701015ff4f"
+checksum = "21a41fed9d98f27ab1c6d161da622a4fa35e8a54a8adc24bbf3ddd0ef70b0e50"
 dependencies = [
  "rustc-std-workspace-core",
 ]
@@ -203,6 +203,7 @@ dependencies = [
 name = "proc_macro"
 version = "0.0.0"
 dependencies = [
+ "core",
  "std",
 ]
 

example/mini_core.rs

@@ -494,13 +494,20 @@ pub trait Deref {
     fn deref(&self) -> &Self::Target;
 }
 
+#[repr(transparent)]
+#[rustc_layout_scalar_valid_range_start(1)]
+#[rustc_nonnull_optimization_guaranteed]
+pub struct NonNull<T: ?Sized>(pub *mut T);
+
+impl<T: ?Sized, U: ?Sized> CoerceUnsized<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
+impl<T: ?Sized, U: ?Sized> DispatchFromDyn<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
+
 pub struct Unique<T: ?Sized> {
-    pub pointer: *const T,
+    pub pointer: NonNull<T>,
     pub _marker: PhantomData<T>,
 }
 
 impl<T: ?Sized, U: ?Sized> CoerceUnsized<Unique<U>> for Unique<T> where T: Unsize<U> {}
-
 impl<T: ?Sized, U: ?Sized> DispatchFromDyn<Unique<U>> for Unique<T> where T: Unsize<U> {}
 
 #[lang = "owned_box"]
@@ -529,7 +536,7 @@ unsafe fn allocate(size: usize, _align: usize) -> *mut u8 {
 
 #[lang = "box_free"]
 unsafe fn box_free<T: ?Sized>(ptr: Unique<T>, alloc: ()) {
-    libc::free(ptr.pointer as *mut u8);
+    libc::free(ptr.pointer.0 as *mut u8);
 }
 
 #[lang = "drop"]

example/mini_core_hello_world.rs

@@ -122,7 +122,7 @@ fn call_return_u128_pair() {
 #[allow(unreachable_code)] // FIXME false positive
 fn main() {
     take_unique(Unique {
-        pointer: 0 as *const (),
+        pointer: unsafe { NonNull(1 as *mut ()) },
         _marker: PhantomData,
     });
     take_f32(0.1);
@@ -173,7 +173,7 @@ fn main() {
         assert!(intrinsics::needs_drop::<NoisyDrop>());
 
         Unique {
-            pointer: 0 as *const &str,
+            pointer: NonNull(1 as *mut &str),
             _marker: PhantomData,
         } as Unique<dyn SomeTrait>;
 

rust-toolchain

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2022-04-05"
+channel = "nightly-2022-04-21"
 components = ["rust-src", "rustc-dev", "llvm-tools-preview"]

src/base.rs

@@ -821,7 +821,8 @@ pub(crate) fn codegen_place<'tcx>(
                 if cplace.layout().ty.is_box() {
                     cplace = cplace
                         .place_field(fx, Field::new(0)) // Box<T> -> Unique<T>
-                        .place_field(fx, Field::new(0)) // Unique<T> -> *const T
+                        .place_field(fx, Field::new(0)) // Unique<T> -> NonNull<T>
+                        .place_field(fx, Field::new(0)) // NonNull<T> -> *mut T
                         .place_deref(fx);
                 } else {
                     cplace = cplace.place_deref(fx);

src/discriminant.rs

@@ -128,8 +128,16 @@ pub(crate) fn codegen_get_discriminant<'tcx>(
             let relative_discr = if niche_start == 0 {
                 tag
             } else {
-                // FIXME handle niche_start > i64::MAX
-                fx.bcx.ins().iadd_imm(tag, -i64::try_from(niche_start).unwrap())
+                let niche_start = match fx.bcx.func.dfg.value_type(tag) {
+                    types::I128 => {
+                        let lsb = fx.bcx.ins().iconst(types::I64, niche_start as u64 as i64);
+                        let msb =
+                            fx.bcx.ins().iconst(types::I64, (niche_start >> 64) as u64 as i64);
+                        fx.bcx.ins().iconcat(lsb, msb)
+                    }
+                    ty => fx.bcx.ins().iconst(ty, niche_start as i64),
+                };
+                fx.bcx.ins().isub(tag, niche_start)
             };
             let relative_max = niche_variants.end().as_u32() - niche_variants.start().as_u32();
             let is_niche = {