parse pinned local variable declarations

Author: frank-king

compiler/rustc_ast/src/ast.rs

@@ -720,18 +720,22 @@ impl ByRef {
 /// Used for both the explicit binding annotations given in the HIR for a binding
 /// and the final binding mode that we infer after type inference/match ergonomics.
 /// `.0` is the by-reference mode (`ref`, `ref mut`, or by value),
-/// `.1` is the mutability of the binding.
+/// `.1` is the pinnedness of the binding,
+/// `.2` is the mutability of the binding.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 #[derive(Encodable, Decodable, HashStable_Generic)]
-pub struct BindingMode(pub ByRef, pub Mutability);
+pub struct BindingMode(pub ByRef, pub Pinnedness, 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 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 NONE: Self = Self(ByRef::No, Pinnedness::Not, Mutability::Not);
+    pub const REF: Self = Self(ByRef::Yes(Mutability::Not), Pinnedness::Not, Mutability::Not);
+    pub const MUT: Self = Self(ByRef::No, Pinnedness::Not, Mutability::Mut);
+    pub const REF_MUT: Self = Self(ByRef::Yes(Mutability::Mut), Pinnedness::Not, Mutability::Not);
+    pub const MUT_REF: Self = Self(ByRef::Yes(Mutability::Not), Pinnedness::Not, Mutability::Mut);
+    pub const MUT_REF_MUT: Self =
+        Self(ByRef::Yes(Mutability::Mut), Pinnedness::Not, Mutability::Mut);
+    pub const PIN_CONST: Self = Self(ByRef::No, Pinnedness::Pinned, Mutability::Not);
+    pub const PIN_MUT: Self = Self(ByRef::No, Pinnedness::Pinned, Mutability::Mut);
 
     pub fn prefix_str(self) -> &'static str {
         match self {
@@ -741,6 +745,9 @@ impl BindingMode {
             Self::REF_MUT => "ref mut ",
             Self::MUT_REF => "mut ref ",
             Self::MUT_REF_MUT => "mut ref mut ",
+            Self::PIN_CONST => "pin const ",
+            Self::PIN_MUT => "pin mut ",
+            Self(_, Pinnedness::Pinned, _) => panic!("unsupported pinned binding mode"),
         }
     }
 }
@@ -2583,7 +2590,9 @@ pub type ExplicitSelf = Spanned<SelfKind>;
 impl Param {
     /// Attempts to cast parameter to `ExplicitSelf`.
     pub fn to_self(&self) -> Option<ExplicitSelf> {
-        if let PatKind::Ident(BindingMode(ByRef::No, mutbl), ident, _) = self.pat.kind {
+        if let PatKind::Ident(BindingMode(ByRef::No, Pinnedness::Not, mutbl), ident, _) =
+            self.pat.kind
+        {
             if ident.name == kw::SelfLower {
                 return match self.ty.kind {
                     TyKind::ImplicitSelf => Some(respan(self.pat.span, SelfKind::Value(mutbl))),
@@ -2638,7 +2647,11 @@ impl Param {
             attrs,
             pat: P(Pat {
                 id: DUMMY_NODE_ID,
-                kind: PatKind::Ident(BindingMode(ByRef::No, mutbl), eself_ident, None),
+                kind: PatKind::Ident(
+                    BindingMode(ByRef::No, Pinnedness::Not, mutbl),
+                    eself_ident,
+                    None,
+                ),
                 span,
                 tokens: None,
             }),

compiler/rustc_ast_ir/src/lib.rs

@@ -86,3 +86,12 @@ pub enum Pinnedness {
     Not,
     Pinned,
 }
+
+impl Pinnedness {
+    pub fn is_pin(self) -> bool {
+        matches!(self, Self::Pinned)
+    }
+    pub fn is_not(self) -> bool {
+        matches!(self, Self::Not)
+    }
+}

compiler/rustc_ast_lowering/src/item.rs

@@ -1275,7 +1275,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
             // Check if this is a binding pattern, if so, we can optimize and avoid adding a
             // `let <pat> = __argN;` statement. In this case, we do not rename the parameter.
             let (ident, is_simple_parameter) = match parameter.pat.kind {
-                hir::PatKind::Binding(hir::BindingMode(ByRef::No, _), _, ident, _) => (ident, true),
+                hir::PatKind::Binding(hir::BindingMode(ByRef::No, _, _), _, ident, _) => {
+                    (ident, true)
+                }
                 // For `ref mut` or wildcard arguments, we can't reuse the binding, but
                 // we can keep the same name for the parameter.
                 // This lets rustdoc render it correctly in documentation.

compiler/rustc_ast_lowering/src/lib.rs

@@ -1641,7 +1641,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             implicit_self: decl.inputs.get(0).map_or(hir::ImplicitSelfKind::None, |arg| {
                 let is_mutable_pat = matches!(
                     arg.pat.kind,
-                    PatKind::Ident(hir::BindingMode(_, Mutability::Mut), ..)
+                    PatKind::Ident(hir::BindingMode(_, _, Mutability::Mut), ..)
                 );
 
                 match &arg.ty.kind {

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1594,7 +1594,10 @@ impl<'a> State<'a> {
         match &pat.kind {
             PatKind::Wild => self.word("_"),
             PatKind::Never => self.word("!"),
-            PatKind::Ident(BindingMode(by_ref, mutbl), ident, sub) => {
+            PatKind::Ident(BindingMode(by_ref, pin, mutbl), ident, sub) => {
+                if pin.is_pin() {
+                    self.word_nbsp("pin");
+                }
                 if mutbl.is_mut() {
                     self.word_nbsp("mut");
                 }

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -305,7 +305,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 {
                     match *decl.local_info() {
                         LocalInfo::User(BindingForm::Var(mir::VarBindingForm {
-                            binding_mode: BindingMode(ByRef::No, Mutability::Not),
+                            binding_mode: BindingMode(ByRef::No, _, Mutability::Not),
                             opt_ty_info: Some(sp),
                             opt_match_place: _,
                             pat_span: _,
@@ -733,7 +733,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         debug!("local_decl: {:?}", local_decl);
         let pat_span = match *local_decl.local_info() {
             LocalInfo::User(BindingForm::Var(mir::VarBindingForm {
-                binding_mode: BindingMode(ByRef::No, Mutability::Not),
+                binding_mode: BindingMode(ByRef::No, _, Mutability::Not),
                 opt_ty_info: _,
                 opt_match_place: _,
                 pat_span,
@@ -1147,7 +1147,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             }
 
             LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
-                binding_mode: BindingMode(ByRef::No, _),
+                binding_mode: BindingMode(ByRef::No, _, _),
                 opt_ty_info,
                 ..
             })) => {
@@ -1226,7 +1226,7 @@ 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;
@@ -1441,7 +1441,7 @@ fn mut_borrow_of_mutable_ref(local_decl: &LocalDecl<'_>, local_name: Option<Symb
     match *local_decl.local_info() {
         // Check if mutably borrowing a mutable reference.
         LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
-            binding_mode: BindingMode(ByRef::No, Mutability::Not),
+            binding_mode: BindingMode(ByRef::No, _, Mutability::Not),
             ..
         })) => matches!(local_decl.ty.kind(), ty::Ref(_, _, hir::Mutability::Mut)),
         LocalInfo::User(mir::BindingForm::ImplicitSelf(kind)) => {

compiler/rustc_builtin_macros/src/deriving/generic/mod.rs

@@ -183,7 +183,7 @@ pub(crate) use SubstructureFields::*;
 use rustc_ast::ptr::P;
 use rustc_ast::{
     self as ast, AnonConst, BindingMode, ByRef, EnumDef, Expr, GenericArg, GenericParamKind,
-    Generics, Mutability, PatKind, VariantData,
+    Generics, Mutability, PatKind, Pinnedness, VariantData,
 };
 use rustc_attr_parsing as attr;
 use rustc_expand::base::{Annotatable, ExtCtxt};
@@ -1468,7 +1468,11 @@ impl<'a> TraitDef<'a> {
                             struct_field.ident,
                             cx.pat(
                                 path.span,
-                                PatKind::Ident(BindingMode(by_ref, Mutability::Not), path, None),
+                                PatKind::Ident(
+                                    BindingMode(by_ref, Pinnedness::Not, Mutability::Not),
+                                    path,
+                                    None,
+                                ),
                             ),
                         )
                     });

compiler/rustc_hir/src/hir.rs

@@ -11,7 +11,7 @@ use rustc_ast::{
 };
 pub use rustc_ast::{
     BinOp, BinOpKind, BindingMode, BorrowKind, BoundConstness, BoundPolarity, ByRef, CaptureBy,
-    ImplPolarity, IsAuto, Movability, Mutability, UnOp, UnsafeBinderCastKind,
+    ImplPolarity, IsAuto, Movability, Mutability, Pinnedness, UnOp, UnsafeBinderCastKind,
 };
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::sorted_map::SortedMap;

compiler/rustc_hir/src/pat_util.rs

@@ -95,7 +95,7 @@ impl hir::Pat<'_> {
 
     pub fn simple_ident(&self) -> Option<Ident> {
         match self.kind {
-            PatKind::Binding(BindingMode(ByRef::No, _), _, ident, None) => Some(ident),
+            PatKind::Binding(BindingMode(ByRef::No, _, _), _, ident, None) => Some(ident),
             _ => None,
         }
     }

compiler/rustc_hir_analysis/src/check/region.rs

@@ -681,7 +681,7 @@ fn resolve_local<'tcx>(
         // & expression, and its lifetime would be extended to the end of the block (due
         // to a different rule, not the below code).
         match pat.kind {
-            PatKind::Binding(hir::BindingMode(hir::ByRef::Yes(_), _), ..) => true,
+            PatKind::Binding(hir::BindingMode(hir::ByRef::Yes(_), _, _), ..) => true,
 
             PatKind::Struct(_, field_pats, _) => field_pats.iter().any(|fp| is_binding_pat(fp.pat)),
 
@@ -700,7 +700,7 @@ fn resolve_local<'tcx>(
             }
 
             PatKind::Ref(_, _)
-            | PatKind::Binding(hir::BindingMode(hir::ByRef::No, _), ..)
+            | PatKind::Binding(hir::BindingMode(hir::ByRef::No, _, _), ..)
             | PatKind::Wild
             | PatKind::Never
             | PatKind::Expr(_)