Project pinned references to pinned fields

Author: frank-king

compiler/rustc_ast/src/ast.rs

@@ -719,14 +719,14 @@ pub struct PatField {
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 #[derive(Encodable, Decodable, HashStable_Generic)]
 pub enum ByRef {
-    Yes(Mutability),
+    Yes(Pinnedness, Mutability),
     No,
 }
 
 impl ByRef {
     #[must_use]
     pub fn cap_ref_mutability(mut self, mutbl: Mutability) -> Self {
-        if let ByRef::Yes(old_mutbl) = &mut self {
+        if let ByRef::Yes(_, old_mutbl) = &mut self {
             *old_mutbl = cmp::min(*old_mutbl, mutbl);
         }
         self
@@ -744,20 +744,33 @@ pub struct BindingMode(pub ByRef, pub Mutability);
 
 impl BindingMode {
     pub const NONE: Self = Self(ByRef::No, Mutability::Not);
-    pub const REF: Self = Self(ByRef::Yes(Mutability::Not), Mutability::Not);
+    pub const REF: Self = Self(ByRef::Yes(Pinnedness::Not, Mutability::Not), Mutability::Not);
+    pub const REF_PIN: Self =
+        Self(ByRef::Yes(Pinnedness::Pinned, Mutability::Not), Mutability::Not);
     pub const MUT: Self = Self(ByRef::No, Mutability::Mut);
-    pub const REF_MUT: Self = Self(ByRef::Yes(Mutability::Mut), Mutability::Not);
-    pub const MUT_REF: Self = Self(ByRef::Yes(Mutability::Not), Mutability::Mut);
-    pub const MUT_REF_MUT: Self = Self(ByRef::Yes(Mutability::Mut), Mutability::Mut);
+    pub const REF_MUT: Self = Self(ByRef::Yes(Pinnedness::Not, Mutability::Mut), Mutability::Not);
+    pub const REF_PIN_MUT: Self =
+        Self(ByRef::Yes(Pinnedness::Pinned, Mutability::Mut), Mutability::Not);
+    pub const MUT_REF: Self = Self(ByRef::Yes(Pinnedness::Not, Mutability::Not), Mutability::Mut);
+    pub const MUT_REF_PIN: Self =
+        Self(ByRef::Yes(Pinnedness::Pinned, Mutability::Not), Mutability::Mut);
+    pub const MUT_REF_MUT: Self =
+        Self(ByRef::Yes(Pinnedness::Not, Mutability::Mut), Mutability::Mut);
+    pub const MUT_REF_PIN_MUT: Self =
+        Self(ByRef::Yes(Pinnedness::Pinned, Mutability::Mut), Mutability::Mut);
 
     pub fn prefix_str(self) -> &'static str {
         match self {
             Self::NONE => "",
             Self::REF => "ref ",
+            Self::REF_PIN => "ref pin const ",
             Self::MUT => "mut ",
             Self::REF_MUT => "ref mut ",
+            Self::REF_PIN_MUT => "ref pin mut ",
             Self::MUT_REF => "mut ref ",
+            Self::MUT_REF_PIN => "mut ref pin ",
             Self::MUT_REF_MUT => "mut ref mut ",
+            Self::MUT_REF_PIN_MUT => "mut ref pin mut ",
         }
     }
 }

compiler/rustc_ast_ir/src/lib.rs

@@ -101,3 +101,10 @@ pub enum Pinnedness {
     Not,
     Pinned,
 }
+
+impl Pinnedness {
+    /// Return `true` if self is pinned
+    pub fn is_pinned(self) -> bool {
+        matches!(self, Self::Pinned)
+    }
+}

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1624,10 +1624,15 @@ impl<'a> State<'a> {
                 if mutbl.is_mut() {
                     self.word_nbsp("mut");
                 }
-                if let ByRef::Yes(rmutbl) = by_ref {
+                if let ByRef::Yes(pinnedness, rmutbl) = by_ref {
                     self.word_nbsp("ref");
+                    if pinnedness.is_pinned() {
+                        self.word_nbsp("pin");
+                    }
                     if rmutbl.is_mut() {
                         self.word_nbsp("mut");
+                    } else if pinnedness.is_pinned() {
+                        self.word_nbsp("const");
                     }
                 }
                 self.print_ident(*ident);

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1225,7 +1225,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             }
 
             LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
-                binding_mode: BindingMode(ByRef::Yes(_), _),
+                binding_mode: BindingMode(ByRef::Yes(..), _),
                 ..
             })) => {
                 let pattern_span: Span = local_decl.source_info.span;
@@ -1588,7 +1588,7 @@ fn suggest_ampmut<'tcx>(
     } else {
         // otherwise, suggest that the user annotates the binding; we provide the
         // type of the local.
-        let ty = decl_ty.builtin_deref(true, tcx).unwrap();
+        let ty = decl_ty.builtin_deref(true).unwrap();
 
         Some(AmpMutSugg {
             has_sugg: false,

compiler/rustc_borrowck/src/lib.rs

@@ -2472,10 +2472,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
 
                         // Check the kind of deref to decide
                         match base_ty.kind() {
-                            _ if let Some((_, _, _, mutbl)) =
-                                base_ty.is_ref_or_pin_ref(self.infcx.tcx) =>
-                            {
-                                // FIXME(pin_ergonomics): handle `&pin mut|const T`
+                            _ if let &ty::Ref(_, _, mutbl) = base_ty.kind() => {
                                 match mutbl {
                                     // Shared borrowed data is never mutable
                                     hir::Mutability::Not => Err(place),
@@ -2516,6 +2513,16 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                             _ => bug!("Deref of unexpected type: {:?}", base_ty),
                         }
                     }
+                    // Check as the inner reference type if it is a field projection
+                    // from the `&pin` pattern
+                    ProjectionElem::Field(FieldIdx::ZERO, _)
+                        if let Some(adt) =
+                            place_base.ty(self.body(), self.infcx.tcx).ty.ty_adt_def()
+                            && adt.is_pin()
+                            && self.infcx.tcx.features().pin_ergonomics() =>
+                    {
+                        self.is_mutable(place_base, is_local_mutation_allowed)
+                    }
                     // All other projections are owned by their base path, so mutable if
                     // base path is mutable
                     ProjectionElem::Field(..)

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1761,7 +1761,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
             } else if let Some(static_def_id) = constant.check_static_ptr(tcx) {
                 let unnormalized_ty = tcx.type_of(static_def_id).instantiate_identity();
                 let normalized_ty = self.normalize(unnormalized_ty, locations);
-                let literal_ty = constant.const_.ty().builtin_deref(true, tcx).unwrap();
+                let literal_ty = constant.const_.ty().builtin_deref(true).unwrap();
 
                 if let Err(terr) =
                     self.eq_types(literal_ty, normalized_ty, locations, ConstraintCategory::Boring)
@@ -2360,9 +2360,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
 
                     debug!("add_reborrow_constraint - base_ty = {:?}", base_ty);
                     match base_ty.kind() {
-                        _ if let Some((ref_region, _, _, mutbl)) =
-                            base_ty.is_ref_or_pin_ref(tcx) =>
-                        {
+                        _ if let &ty::Ref(ref_region, _, mutbl) = base_ty.kind() => {
                             // FIXME(pin_ergonomics): handle `&pin mut|const T`
                             constraints.outlives_constraints.push(OutlivesConstraint {
                                 sup: ref_region.as_var(),

compiler/rustc_codegen_llvm/src/abi.rs

@@ -626,7 +626,7 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
         let element_type_index = unsafe { llvm::LLVMRustGetElementTypeArgIndex(callsite) };
         if element_type_index >= 0 {
             let arg_ty = self.args[element_type_index as usize].layout.ty;
-            let pointee_ty = arg_ty.builtin_deref(true, bx.tcx).expect("Must be pointer argument");
+            let pointee_ty = arg_ty.builtin_deref(true).expect("Must be pointer argument");
             let element_type_attr = unsafe {
                 llvm::LLVMRustCreateElementTypeAttr(bx.llcx, bx.layout_of(pointee_ty).llvm_type(bx))
             };

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -2532,7 +2532,7 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
 
     if name == sym::simd_arith_offset {
         // This also checks that the first operand is a ptr type.
-        let pointee = in_elem.builtin_deref(true, bx.tcx).unwrap_or_else(|| {
+        let pointee = in_elem.builtin_deref(true).unwrap_or_else(|| {
             span_bug!(span, "must be called with a vector of pointer types as first argument")
         });
         let layout = bx.layout_of(pointee);

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -1106,7 +1106,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
 
                         // Make sure that we've actually unwrapped the rcvr down
                         // to a pointer or ref to `dyn* Trait`.
-                        if !op.layout.ty.builtin_deref(true, bx.tcx()).unwrap().is_dyn_star() {
+                        if !op.layout.ty.builtin_deref(true).unwrap().is_dyn_star() {
                             span_bug!(span, "can't codegen a virtual call on {:#?}", op);
                         }
                         let place = op.deref(bx.cx());

compiler/rustc_codegen_ssa/src/mir/debuginfo.rs

@@ -130,9 +130,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> DebugInfoOffsetLocation<'tcx, Bx>
 {
     fn deref(&self, bx: &mut Bx) -> Self {
         bx.cx().layout_of(
-            self.ty
-                .builtin_deref(true, bx.tcx())
-                .unwrap_or_else(|| bug!("cannot deref `{}`", self.ty)),
+            self.ty.builtin_deref(true).unwrap_or_else(|| bug!("cannot deref `{}`", self.ty)),
         )
     }