Initial implementation of UnsafePinned and UnsafeUnpin

Author: Sky9x

compiler/rustc_abi/src/layout.rs

@@ -240,7 +240,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         repr: &ReprOptions,
         variants: &IndexSlice<VariantIdx, IndexVec<FieldIdx, F>>,
         is_enum: bool,
-        is_unsafe_cell: bool,
+        is_special_no_niche: bool,
         scalar_valid_range: (Bound<u128>, Bound<u128>),
         discr_range_of_repr: impl Fn(i128, i128) -> (Integer, bool),
         discriminants: impl Iterator<Item = (VariantIdx, i128)>,
@@ -273,7 +273,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                 repr,
                 variants,
                 is_enum,
-                is_unsafe_cell,
+                is_special_no_niche,
                 scalar_valid_range,
                 always_sized,
                 present_first,
@@ -418,7 +418,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         repr: &ReprOptions,
         variants: &IndexSlice<VariantIdx, IndexVec<FieldIdx, F>>,
         is_enum: bool,
-        is_unsafe_cell: bool,
+        is_special_no_niche: bool,
         scalar_valid_range: (Bound<u128>, Bound<u128>),
         always_sized: bool,
         present_first: VariantIdx,
@@ -437,7 +437,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         let mut st = self.univariant(&variants[v], repr, kind)?;
         st.variants = Variants::Single { index: v };
 
-        if is_unsafe_cell {
+        if is_special_no_niche {
             let hide_niches = |scalar: &mut _| match scalar {
                 Scalar::Initialized { value, valid_range } => {
                     *valid_range = WrappingRange::full(value.size(dl))

compiler/rustc_abi/src/lib.rs

@@ -1828,11 +1828,12 @@ where
 pub enum PointerKind {
     /// Shared reference. `frozen` indicates the absence of any `UnsafeCell`.
     SharedRef { frozen: bool },
-    /// Mutable reference. `unpin` indicates the absence of any pinned data.
-    MutableRef { unpin: bool },
-    /// Box. `unpin` indicates the absence of any pinned data. `global` indicates whether this box
-    /// uses the global allocator or a custom one.
-    Box { unpin: bool, global: bool },
+    /// Mutable reference. `unsafe_unpin` indicates the absence of any pinned
+    /// data (`UnsafePinned` or `PhantomPinned`).
+    MutableRef { unsafe_unpin: bool },
+    /// Box. `unsafe_unpin` indicates the absence of any pinned data. `global`
+    /// indicates whether this box uses the global allocator or a custom one.
+    Box { unsafe_unpin: bool, global: bool },
 }
 
 /// Encodes extra information we have about a pointer.

compiler/rustc_ast_ir/src/lib.rs

@@ -11,13 +11,14 @@ use rustc_macros::{Decodable, Encodable, HashStable_NoContext};
 pub mod visit;
 
 /// The movability of a coroutine / closure literal:
-/// whether a coroutine contains self-references, causing it to be `!Unpin`.
+/// whether a coroutine contains self-references, causing it to be
+/// `!Unpin + !UnsafeUnpin`.
 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Copy)]
 #[cfg_attr(feature = "nightly", derive(Encodable, Decodable, HashStable_NoContext))]
 pub enum Movability {
-    /// May contain self-references, `!Unpin`.
+    /// May contain self-references, `!Unpin + !UnsafeUnpin`.
     Static,
-    /// Must not contain self-references, `Unpin`.
+    /// Must not contain self-references, `!Unpin + !UnsafeUnpin`.
     Movable,
 }
 

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -3407,7 +3407,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     Some(3)
                 } else if string.starts_with("static") {
                     // `static` is 6 chars long
-                    // This is used for `!Unpin` coroutines
+                    // This is used for immovable (self-referential) coroutines
                     Some(6)
                 } else {
                     None

compiler/rustc_codegen_ssa/src/traits/type_.rs

@@ -81,10 +81,6 @@ pub trait DerivedTypeCodegenMethods<'tcx>:
         ty.is_sized(self.tcx(), self.typing_env())
     }
 
-    fn type_is_freeze(&self, ty: Ty<'tcx>) -> bool {
-        ty.is_freeze(self.tcx(), self.typing_env())
-    }
-
     fn type_has_metadata(&self, ty: Ty<'tcx>) -> bool {
         if ty.is_sized(self.tcx(), self.typing_env()) {
             return false;

compiler/rustc_hir/src/lang_items.rs

@@ -181,6 +181,7 @@ language_item_table! {
     DynMetadata,             sym::dyn_metadata,        dyn_metadata,               Target::Struct,         GenericRequirement::None;
 
     Freeze,                  sym::freeze,              freeze_trait,               Target::Trait,          GenericRequirement::Exact(0);
+    UnsafeUnpin,             sym::unsafe_unpin,        unsafe_unpin_trait,         Target::Trait,          GenericRequirement::Exact(0);
 
     FnPtrTrait,              sym::fn_ptr_trait,        fn_ptr_trait,               Target::Trait,          GenericRequirement::Exact(0);
     FnPtrAddr,               sym::fn_ptr_addr,         fn_ptr_addr,                Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
@@ -234,6 +235,8 @@ language_item_table! {
     IndexMut,                sym::index_mut,           index_mut_trait,            Target::Trait,          GenericRequirement::Exact(1);
 
     UnsafeCell,              sym::unsafe_cell,         unsafe_cell_type,           Target::Struct,         GenericRequirement::None;
+    UnsafePinned,            sym::unsafe_pinned,       unsafe_pinned_type,         Target::Struct,         GenericRequirement::None;
+
     VaList,                  sym::va_list,             va_list,                    Target::Struct,         GenericRequirement::None;
 
     Deref,                   sym::deref,               deref_trait,                Target::Trait,          GenericRequirement::Exact(0);

compiler/rustc_lint/src/types.rs

@@ -867,8 +867,8 @@ fn ty_is_known_nonnull<'tcx>(
                 return true;
             }
 
-            // `UnsafeCell` has its niche hidden.
-            if def.is_unsafe_cell() {
+            // `UnsafeCell` and `UnsafePinned` have their niche hidden.
+            if def.is_unsafe_cell() || def.is_unsafe_pinned() {
                 return false;
             }
 

compiler/rustc_middle/src/query/mod.rs

@@ -1527,9 +1527,9 @@ rustc_queries! {
     query is_freeze_raw(env: ty::PseudoCanonicalInput<'tcx, Ty<'tcx>>) -> bool {
         desc { "computing whether `{}` is freeze", env.value }
     }
-    /// Query backing `Ty::is_unpin`.
-    query is_unpin_raw(env: ty::PseudoCanonicalInput<'tcx, Ty<'tcx>>) -> bool {
-        desc { "computing whether `{}` is `Unpin`", env.value }
+    /// Query backing `Ty::is_unsafe_unpin`.
+    query is_unsafe_unpin_raw(env: ty::PseudoCanonicalInput<'tcx, Ty<'tcx>>) -> bool {
+        desc { "computing whether `{}` is `UnsafeUnpin`", env.value }
     }
     /// Query backing `Ty::needs_drop`.
     query needs_drop_raw(env: ty::PseudoCanonicalInput<'tcx, Ty<'tcx>>) -> bool {

compiler/rustc_middle/src/ty/adt.rs

@@ -54,8 +54,10 @@ bitflags::bitflags! {
         const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
         /// Indicates whether the type is `UnsafeCell`.
         const IS_UNSAFE_CELL              = 1 << 9;
+        /// Indicates whether the type is `UnsafePinned`.
+        const IS_UNSAFE_PINNED              = 1 << 10;
         /// Indicates whether the type is anonymous.
-        const IS_ANONYMOUS                = 1 << 10;
+        const IS_ANONYMOUS                = 1 << 11;
     }
 }
 rustc_data_structures::external_bitflags_debug! { AdtFlags }
@@ -301,6 +303,9 @@ impl AdtDefData {
         if tcx.is_lang_item(did, LangItem::UnsafeCell) {
             flags |= AdtFlags::IS_UNSAFE_CELL;
         }
+        if tcx.is_lang_item(did, LangItem::UnsafePinned) {
+            flags |= AdtFlags::IS_UNSAFE_PINNED;
+        }
 
         AdtDefData { did, variants, flags, repr }
     }
@@ -393,6 +398,12 @@ impl<'tcx> AdtDef<'tcx> {
         self.flags().contains(AdtFlags::IS_UNSAFE_CELL)
     }
 
+    /// Returns `true` if this is `UnsafePinned<T>`.
+    #[inline]
+    pub fn is_unsafe_pinned(self) -> bool {
+        self.flags().contains(AdtFlags::IS_UNSAFE_PINNED)
+    }
+
     /// Returns `true` if this is `ManuallyDrop<T>`.
     #[inline]
     pub fn is_manually_drop(self) -> bool {

compiler/rustc_middle/src/ty/context.rs

@@ -717,6 +717,7 @@ bidirectional_lang_item_map! {
     TransmuteTrait,
     Tuple,
     Unpin,
+    UnsafeUnpin,
     Unsize,
 // tidy-alphabetical-end
 }