Start using pattern types in libcore

compiler/rustc_builtin_macros/src/pattern_type.rs

@@ -80,6 +80,7 @@ fn pat_to_ty_pat(cx: &mut ExtCtxt<'_>, pat: ast::Pat) -> TyPat {
             TyPatKind::Or(variants.into_iter().map(|pat| pat_to_ty_pat(cx, pat)).collect())
         }
         ast::PatKind::Err(guar) => TyPatKind::Err(guar),
+        ast::PatKind::Paren(p) => pat_to_ty_pat(cx, *p).kind,
         _ => TyPatKind::Err(cx.dcx().span_err(pat.span, "pattern not supported in pattern types")),
     };
     ty_pat(kind, pat.span)

compiler/rustc_codegen_cranelift/example/mini_core.rs

@@ -8,13 +8,38 @@
     rustc_attrs,
     rustc_private,
     transparent_unions,
+    pattern_types,
     auto_traits,
     freeze_impls
 )]
 #![cfg_attr(not(all(windows, target_env = "gnu")), feature(thread_local))]
 #![no_core]
 #![allow(dead_code, internal_features, ambiguous_wide_pointer_comparisons)]
 
+#[lang = "pointee_trait"]
+pub trait Pointee: PointeeSized {
+    #[lang = "metadata_type"]
+    // needed so that layout_of will return `TooGeneric` instead of `Unknown`
+    // when asked for the layout of `*const T`. Which is important for making
+    // transmutes between raw pointers (and especially pattern types of raw pointers)
+    // work.
+    type Metadata: Copy + Sync + Unpin + Freeze;
+}
+
+#[lang = "dyn_metadata"]
+pub struct DynMetadata<Dyn: PointeeSized> {
+    _vtable_ptr: NonNull<VTable>,
+    _phantom: PhantomData<Dyn>,
+}
+
+unsafe extern "C" {
+    /// Opaque type for accessing vtables.
+    ///
+    /// Private implementation detail of `DynMetadata::size_of` etc.
+    /// There is conceptually not actually any Abstract Machine memory behind this pointer.
+    type VTable;
+}
+
 #[lang = "pointee_sized"]
 pub trait PointeeSized {}
 
@@ -105,7 +130,7 @@ unsafe impl<'a, T: PointeeSized> Sync for &'a T {}
 unsafe impl<T: Sync, const N: usize> Sync for [T; N] {}
 
 #[lang = "freeze"]
-unsafe auto trait Freeze {}
+pub unsafe auto trait Freeze {}
 
 unsafe impl<T: PointeeSized> Freeze for PhantomData<T> {}
 unsafe impl<T: PointeeSized> Freeze for *const T {}
@@ -570,10 +595,24 @@ pub trait Deref {
     fn deref(&self) -> &Self::Target;
 }
 
+#[rustc_builtin_macro(pattern_type)]
+#[macro_export]
+macro_rules! pattern_type {
+    ($($arg:tt)*) => {
+        /* compiler built-in */
+    };
+}
+
+impl<T: PointeeSized, U: PointeeSized> CoerceUnsized<pattern_type!(*const U is !null)> for pattern_type!(*const T is !null) where
+    T: Unsize<U>
+{
+}
+
+impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<pattern_type!(U is !null)> for pattern_type!(T is !null) {}
+
 #[repr(transparent)]
-#[rustc_layout_scalar_valid_range_start(1)]
 #[rustc_nonnull_optimization_guaranteed]
-pub struct NonNull<T: PointeeSized>(pub *const T);
+pub struct NonNull<T: PointeeSized>(pub pattern_type!(*const T is !null));
 
 impl<T: PointeeSized, U: PointeeSized> CoerceUnsized<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
 impl<T: PointeeSized, U: PointeeSized> DispatchFromDyn<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
@@ -600,7 +639,16 @@ impl<T> Box<T> {
             let size = size_of::<T>();
             let ptr = libc::malloc(size);
             intrinsics::copy(&val as *const T as *const u8, ptr, size);
-            Box(Unique { pointer: NonNull(ptr as *const T), _marker: PhantomData }, Global)
+            Box(
+                Unique {
+                    pointer: NonNull(intrinsics::transmute::<
+                        *mut u8,
+                        pattern_type!(*const T is !null),
+                    >(ptr)),
+                    _marker: PhantomData,
+                },
+                Global,
+            )
         }
     }
 }
@@ -609,7 +657,9 @@ impl<T: ?Sized, A> Drop for Box<T, A> {
     fn drop(&mut self) {
         // inner value is dropped by compiler
         unsafe {
-            libc::free(self.0.pointer.0 as *mut u8);
+            libc::free(intrinsics::transmute::<pattern_type!(*const T is !null), *const T>(
+                self.0.pointer.0,
+            ) as *mut u8);
         }
     }
 }

compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs

@@ -1,4 +1,13 @@
-#![feature(no_core, lang_items, never_type, extern_types, thread_local, repr_simd, rustc_private)]
+#![feature(
+    no_core,
+    lang_items,
+    never_type,
+    extern_types,
+    thread_local,
+    repr_simd,
+    pattern_types,
+    rustc_private
+)]
 #![cfg_attr(not(any(jit, target_vendor = "apple", windows)), feature(linkage))]
 #![no_core]
 #![allow(dead_code, non_camel_case_types, internal_features)]
@@ -153,7 +162,10 @@ extern "C" fn bool_struct_in_11(_arg0: bool_11) {}
 
 #[allow(unreachable_code)] // FIXME false positive
 fn main() {
-    take_unique(Unique { pointer: unsafe { NonNull(1 as *mut ()) }, _marker: PhantomData });
+    take_unique(Unique {
+        pointer: unsafe { NonNull(intrinsics::transmute(1 as *mut ())) },
+        _marker: PhantomData,
+    });
     take_f32(0.1);
 
     call_return_u128_pair();
@@ -219,7 +231,12 @@ fn main() {
         let noisy_unsized_drop = const { intrinsics::needs_drop::<NoisyDropUnsized>() };
         assert!(noisy_unsized_drop);
 
-        Unique { pointer: NonNull(1 as *mut &str), _marker: PhantomData } as Unique<dyn SomeTrait>;
+        Unique {
+            pointer: NonNull(intrinsics::transmute::<_, pattern_type!(*const &str is !null)>(
+                1 as *mut &str,
+            )),
+            _marker: PhantomData,
+        } as Unique<dyn SomeTrait>;
 
         struct MyDst<T: ?Sized>(T);
 

compiler/rustc_codegen_gcc/example/mini_core.rs

@@ -9,6 +9,7 @@
     transparent_unions,
     auto_traits,
     freeze_impls,
+    pattern_types,
     thread_local
 )]
 #![no_core]
@@ -580,9 +581,16 @@ pub struct Global;
 impl Allocator for Global {}
 
 #[repr(transparent)]
-#[rustc_layout_scalar_valid_range_start(1)]
 #[rustc_nonnull_optimization_guaranteed]
-pub struct NonNull<T: PointeeSized>(pub *const T);
+pub struct NonNull<T: PointeeSized>(pub pattern_type!(*const T is !null));
+
+#[rustc_builtin_macro(pattern_type)]
+#[macro_export]
+macro_rules! pattern_type {
+    ($($arg:tt)*) => {
+        /* compiler built-in */
+    };
+}
 
 impl<T: PointeeSized, U: PointeeSized> CoerceUnsized<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
 impl<T: PointeeSized, U: PointeeSized> DispatchFromDyn<NonNull<U>> for NonNull<T> where T: Unsize<U> {}

compiler/rustc_codegen_ssa/src/base.rs

@@ -27,7 +27,7 @@ use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::mono::{CodegenUnit, CodegenUnitNameBuilder, MonoItem, MonoItemPartitions};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::layout::{HasTyCtxt, HasTypingEnv, LayoutOf, TyAndLayout};
-use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
+use rustc_middle::ty::{self, Instance, PatternKind, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_session::Session;
 use rustc_session::config::{self, CrateType, EntryFnType};
@@ -273,6 +273,13 @@ pub(crate) fn coerce_unsized_into<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     let src_ty = src.layout.ty;
     let dst_ty = dst.layout.ty;
     match (src_ty.kind(), dst_ty.kind()) {
+        (&ty::Pat(s, sp), &ty::Pat(d, dp))
+            if let (PatternKind::NotNull, PatternKind::NotNull) = (*sp, *dp) =>
+        {
+            let src = src.project_type(bx, s);
+            let dst = dst.project_type(bx, d);
+            coerce_unsized_into(bx, src, dst)
+        }
         (&ty::Ref(..), &ty::Ref(..) | &ty::RawPtr(..)) | (&ty::RawPtr(..), &ty::RawPtr(..)) => {
             let (base, info) = match bx.load_operand(src).val {
                 OperandValue::Pair(base, info) => unsize_ptr(bx, base, src_ty, dst_ty, Some(info)),

compiler/rustc_const_eval/src/interpret/visitor.rs

@@ -124,7 +124,12 @@ pub trait ValueVisitor<'tcx, M: Machine<'tcx>>: Sized {
 
                 // ... that contains a `NonNull`... (gladly, only a single field here)
                 assert_eq!(nonnull_ptr.layout().fields.count(), 1);
-                let raw_ptr = self.ecx().project_field(&nonnull_ptr, FieldIdx::ZERO)?; // the actual raw ptr
+                let pat_ty = self.ecx().project_field(&nonnull_ptr, FieldIdx::ZERO)?; // `*mut T is !null`
+                let base = match *pat_ty.layout().ty.kind() {
+                    ty::Pat(base, _) => self.ecx().layout_of(base)?,
+                    _ => unreachable!(),
+                };
+                let raw_ptr = pat_ty.transmute(base, self.ecx())?; // The actual raw pointer
 
                 // ... whose only field finally is a raw ptr we can dereference.
                 self.visit_box(ty, &raw_ptr)?;

compiler/rustc_mir_transform/src/add_retag.rs

@@ -24,6 +24,7 @@ fn may_contain_reference<'tcx>(ty: Ty<'tcx>, depth: u32, tcx: TyCtxt<'tcx>) -> b
         | ty::Str
         | ty::FnDef(..)
         | ty::Never => false,
+        ty::Pat(base, ..) => may_contain_reference(*base, depth, tcx),
         // References and Boxes (`noalias` sources)
         ty::Ref(..) => true,
         ty::Adt(..) if ty.is_box() => true,

compiler/rustc_mir_transform/src/elaborate_box_derefs.rs

@@ -6,7 +6,7 @@ use rustc_abi::FieldIdx;
 use rustc_middle::mir::visit::MutVisitor;
 use rustc_middle::mir::*;
 use rustc_middle::span_bug;
-use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::ty::{self, PatternKind, Ty, TyCtxt};
 
 use crate::patch::MirPatch;
 
@@ -137,8 +137,10 @@ impl<'tcx> crate::MirPass<'tcx> for ElaborateBoxDerefs {
                             build_ptr_tys(tcx, boxed_ty, unique_def, nonnull_def);
 
                         new_projections.extend_from_slice(&build_projection(unique_ty, nonnull_ty));
-                        // While we can't project into `NonNull<_>` in a basic block
-                        // due to MCP#807, this is debug info where it's fine.
+                        // While we can't project into a pattern type in a basic block,
+                        // this is debug info where it's fine.
+                        let pat_ty = Ty::new_pat(tcx, ptr_ty, tcx.mk_pat(PatternKind::NotNull));
+                        new_projections.push(PlaceElem::Field(FieldIdx::ZERO, pat_ty));
                         new_projections.push(PlaceElem::Field(FieldIdx::ZERO, ptr_ty));
                         new_projections.push(PlaceElem::Deref);
                     } else if let Some(new_projections) = new_projections.as_mut() {

library/core/src/marker.rs

@@ -937,6 +937,8 @@ marker_impls! {
         {T: PointeeSized} *mut T,
         {T: PointeeSized} &T,
         {T: PointeeSized} &mut T,
+        {T: PointeeSized} pattern_type!(*const T is !null),
+        {T: PointeeSized} pattern_type!(*mut T is !null),
 }
 
 /// Types that do not require any pinning guarantees.

library/core/src/ptr/non_null.rs

@@ -69,13 +69,10 @@ use crate::{fmt, hash, intrinsics, mem, ptr};
 /// [null pointer optimization]: crate::option#representation
 #[stable(feature = "nonnull", since = "1.25.0")]
 #[repr(transparent)]
-#[rustc_layout_scalar_valid_range_start(1)]
 #[rustc_nonnull_optimization_guaranteed]
 #[rustc_diagnostic_item = "NonNull"]
 pub struct NonNull<T: PointeeSized> {
-    // Remember to use `.as_ptr()` instead of `.pointer`, as field projecting to
-    // this is banned by <https://github.com/rust-lang/compiler-team/issues/807>.
-    pointer: *const T,
+    pointer: crate::pattern_type!(*const T is !null),
 }
 
 /// `NonNull` pointers are not `Send` because the data they reference may be aliased.

library/std/src/os/unix/io/tests.rs

@@ -2,8 +2,7 @@ use crate::os::unix::io::RawFd;
 
 #[test]
 fn test_raw_fd_layout() {
-    // `OwnedFd` and `BorrowedFd` use `rustc_layout_scalar_valid_range_start`
-    // and `rustc_layout_scalar_valid_range_end`, with values that depend on
+    // `OwnedFd` and `BorrowedFd` use pattern types, with ranges that depend on
     // the bit width of `RawFd`. If this ever changes, those values will need
     // to be updated.
     assert_eq!(size_of::<RawFd>(), 4);

library/std/src/os/wasi/io/tests.rs

@@ -2,8 +2,7 @@ use crate::os::wasi::io::RawFd;
 
 #[test]
 fn test_raw_fd_layout() {
-    // `OwnedFd` and `BorrowedFd` use `rustc_layout_scalar_valid_range_start`
-    // and `rustc_layout_scalar_valid_range_end`, with values that depend on
+    // `OwnedFd` and `BorrowedFd` use pattern types with ranges that depend on
     // the bit width of `RawFd`. If this ever changes, those values will need
     // to be updated.
     assert_eq!(size_of::<RawFd>(), 4);

src/tools/clippy/clippy_lints/src/transmute/transmute_undefined_repr.rs

@@ -242,6 +242,10 @@ fn reduce_ty<'tcx>(cx: &LateContext<'tcx>, mut ty: Ty<'tcx>) -> ReducedTy<'tcx>
     loop {
         ty = cx.tcx.try_normalize_erasing_regions(cx.typing_env(), ty).unwrap_or(ty);
         return match *ty.kind() {
+            ty::Pat(base, _) => {
+                ty = base;
+                continue;
+            },
             ty::Array(sub_ty, _) if matches!(sub_ty.kind(), ty::Int(_) | ty::Uint(_)) => {
                 ReducedTy::TypeErasure { raw_ptr_only: false }
             },

tests/auxiliary/minicore.rs

@@ -22,6 +22,7 @@
     auto_traits,
     freeze_impls,
     negative_impls,
+    pattern_types,
     rustc_attrs,
     decl_macro,
     f16,
@@ -127,17 +128,42 @@ pub struct ManuallyDrop<T: PointeeSized> {
 impl<T: Copy + PointeeSized> Copy for ManuallyDrop<T> {}
 
 #[repr(transparent)]
-#[rustc_layout_scalar_valid_range_start(1)]
 #[rustc_nonnull_optimization_guaranteed]
 pub struct NonNull<T: ?Sized> {
-    pointer: *const T,
+    pointer: pattern_type!(*const T is !null),
 }
 impl<T: ?Sized> Copy for NonNull<T> {}
 
 #[repr(transparent)]
-#[rustc_layout_scalar_valid_range_start(1)]
 #[rustc_nonnull_optimization_guaranteed]
-pub struct NonZero<T>(T);
+pub struct NonZero<T: ZeroablePrimitive>(T::NonZeroInner);
+
+pub trait ZeroablePrimitive {
+    type NonZeroInner;
+}
+
+macro_rules! define_valid_range_type {
+    ($(
+        $name:ident($int:ident is $pat:pat);
+    )+) => {$(
+        #[repr(transparent)]
+        pub struct $name(pattern_type!($int is $pat));
+
+        impl ZeroablePrimitive for $int {
+            type NonZeroInner = $name;
+        }
+    )+};
+}
+
+define_valid_range_type! {
+    NonZeroU8Inner(u8 is 1..=0xFF);
+    NonZeroU16Inner(u16 is 1..=0xFFFF);
+    NonZeroU32Inner(u32 is 1..=0xFFFF_FFFF);
+    NonZeroU64Inner(u64 is 1..=0xFFFF_FFFF_FFFF_FFFF);
+
+    NonZeroI8Inner(i8 is (-128..=-1 | 1..=0x7F));
+    NonZeroI32Inner(i32 is (-0x8000_0000..=-1 | 1..=0x7FFF_FFFF));
+}
 
 pub struct Unique<T: ?Sized> {
     pub pointer: NonNull<T>,
@@ -225,6 +251,14 @@ impl Neg for i8 {
     }
 }
 
+impl Neg for i32 {
+    type Output = i32;
+
+    fn neg(self) -> i32 {
+        loop {}
+    }
+}
+
 #[lang = "sync"]
 pub trait Sync {}
 impl_marker_trait!(
@@ -314,6 +348,14 @@ pub enum c_void {
     __variant2,
 }
 
+#[rustc_builtin_macro(pattern_type)]
+#[macro_export]
+macro_rules! pattern_type {
+    ($($arg:tt)*) => {
+        /* compiler built-in */
+    };
+}
+
 #[lang = "Ordering"]
 #[repr(i8)]
 pub enum Ordering {

tests/mir-opt/const_prop/transmute.unreachable_box.GVN.32bit.diff

@@ -13,8 +13,8 @@
           StorageLive(_1);
 -         _1 = const 1_usize as std::boxed::Box<Never> (Transmute);
 -         _2 = copy ((_1.0: std::ptr::Unique<Never>).0: std::ptr::NonNull<Never>) as *const Never (Transmute);
-+         _1 = const Box::<Never>(std::ptr::Unique::<Never> {{ pointer: NonNull::<Never> {{ pointer: {0x1 as *const Never} }}, _marker: PhantomData::<Never> }}, std::alloc::Global);
-+         _2 = const std::ptr::NonNull::<Never> {{ pointer: {0x1 as *const Never} }} as *const Never (Transmute);
++         _1 = const Box::<Never>(std::ptr::Unique::<Never> {{ pointer: NonNull::<Never> {{ pointer: {0x1 as *const Never} is !null }}, _marker: PhantomData::<Never> }}, std::alloc::Global);
++         _2 = const std::ptr::NonNull::<Never> {{ pointer: {0x1 as *const Never} is !null }} as *const Never (Transmute);
           unreachable;
       }
   }