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eholkeholk
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Add sugar for &pin (const|mut) types
1 parent a18800f commit bd45002

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23 files changed

+243
-41
lines changed

23 files changed

+243
-41
lines changed

‎compiler/rustc_ast/src/ast.rs

+7-2
Original file line numberDiff line numberDiff line change
@@ -21,7 +21,7 @@
2121
use std::borrow::Cow;
2222
use std::{cmp, fmt, mem};
2323

24-
pub use rustc_ast_ir::{Movability, Mutability};
24+
pub use rustc_ast_ir::{Movability, Mutability, Pinnedness};
2525
use rustc_data_structures::packed::Pu128;
2626
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
2727
use rustc_data_structures::stack::ensure_sufficient_stack;
@@ -2159,6 +2159,8 @@ pub enum TyKind {
21592159
Ptr(MutTy),
21602160
/// A reference (`&'a T` or `&'a mut T`).
21612161
Ref(Option<Lifetime>, MutTy),
2162+
/// A pinned reference (`&'a pin const T` or `&'a pin mut T`).
2163+
PinnedRef(Option<Lifetime>, MutTy),
21622164
/// A bare function (e.g., `fn(usize) -> bool`).
21632165
BareFn(P<BareFnTy>),
21642166
/// The never type (`!`).
@@ -2481,7 +2483,10 @@ impl Param {
24812483
if ident.name == kw::SelfLower {
24822484
return match self.ty.kind {
24832485
TyKind::ImplicitSelf => Some(respan(self.pat.span, SelfKind::Value(mutbl))),
2484-
TyKind::Ref(lt, MutTy { ref ty, mutbl }) if ty.kind.is_implicit_self() => {
2486+
TyKind::Ref(lt, MutTy { ref ty, mutbl })
2487+
| TyKind::PinnedRef(lt, MutTy { ref ty, mutbl })
2488+
if ty.kind.is_implicit_self() =>
2489+
{
24852490
Some(respan(self.pat.span, SelfKind::Region(lt, mutbl)))
24862491
}
24872492
_ => Some(respan(

‎compiler/rustc_ast/src/mut_visit.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -485,7 +485,7 @@ pub fn walk_ty<T: MutVisitor>(vis: &mut T, ty: &mut P<Ty>) {
485485
}
486486
TyKind::Slice(ty) => vis.visit_ty(ty),
487487
TyKind::Ptr(mt) => vis.visit_mt(mt),
488-
TyKind::Ref(lt, mt) => {
488+
TyKind::Ref(lt, mt) | TyKind::PinnedRef(lt, mt) => {
489489
visit_opt(lt, |lt| vis.visit_lifetime(lt));
490490
vis.visit_mt(mt);
491491
}

‎compiler/rustc_ast/src/util/classify.rs

+3-1
Original file line numberDiff line numberDiff line change
@@ -247,7 +247,9 @@ fn type_trailing_braced_mac_call(mut ty: &ast::Ty) -> Option<&ast::MacCall> {
247247
break (mac.args.delim == Delimiter::Brace).then_some(mac);
248248
}
249249

250-
ast::TyKind::Ptr(mut_ty) | ast::TyKind::Ref(_, mut_ty) => {
250+
ast::TyKind::Ptr(mut_ty)
251+
| ast::TyKind::Ref(_, mut_ty)
252+
| ast::TyKind::PinnedRef(_, mut_ty) => {
251253
ty = &mut_ty.ty;
252254
}
253255

‎compiler/rustc_ast/src/visit.rs

+2-1
Original file line numberDiff line numberDiff line change
@@ -499,7 +499,8 @@ pub fn walk_ty<'a, V: Visitor<'a>>(visitor: &mut V, typ: &'a Ty) -> V::Result {
499499
match kind {
500500
TyKind::Slice(ty) | TyKind::Paren(ty) => try_visit!(visitor.visit_ty(ty)),
501501
TyKind::Ptr(MutTy { ty, mutbl: _ }) => try_visit!(visitor.visit_ty(ty)),
502-
TyKind::Ref(opt_lifetime, MutTy { ty, mutbl: _ }) => {
502+
TyKind::Ref(opt_lifetime, MutTy { ty, mutbl: _ })
503+
| TyKind::PinnedRef(opt_lifetime, MutTy { ty, mutbl: _ }) => {
503504
visit_opt!(visitor, visit_lifetime, opt_lifetime, LifetimeCtxt::Ref);
504505
try_visit!(visitor.visit_ty(ty));
505506
}

‎compiler/rustc_ast_ir/src/lib.rs

+7
Original file line numberDiff line numberDiff line change
@@ -79,3 +79,10 @@ impl Mutability {
7979
matches!(self, Self::Not)
8080
}
8181
}
82+
83+
#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Copy)]
84+
#[cfg_attr(feature = "nightly", derive(Encodable, Decodable, HashStable_NoContext))]
85+
pub enum Pinnedness {
86+
Not,
87+
Pinned,
88+
}

‎compiler/rustc_ast_lowering/src/expr.rs

+3-2
Original file line numberDiff line numberDiff line change
@@ -638,7 +638,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
638638
self.lower_span(span),
639639
Some(self.allow_gen_future.clone()),
640640
);
641-
let resume_ty = self.make_lang_item_qpath(hir::LangItem::ResumeTy, unstable_span);
641+
let resume_ty =
642+
self.make_lang_item_qpath(hir::LangItem::ResumeTy, unstable_span, None);
642643
let input_ty = hir::Ty {
643644
hir_id: self.next_id(),
644645
kind: hir::TyKind::Path(resume_ty),
@@ -2063,7 +2064,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
20632064
lang_item: hir::LangItem,
20642065
name: Symbol,
20652066
) -> hir::Expr<'hir> {
2066-
let qpath = self.make_lang_item_qpath(lang_item, self.lower_span(span));
2067+
let qpath = self.make_lang_item_qpath(lang_item, self.lower_span(span), None);
20672068
let path = hir::ExprKind::Path(hir::QPath::TypeRelative(
20682069
self.arena.alloc(self.ty(span, hir::TyKind::Path(qpath))),
20692070
self.arena.alloc(hir::PathSegment::new(

‎compiler/rustc_ast_lowering/src/lib.rs

+43-8
Original file line numberDiff line numberDiff line change
@@ -55,8 +55,8 @@ use rustc_errors::{DiagArgFromDisplay, DiagCtxtHandle, StashKey};
5555
use rustc_hir::def::{DefKind, LifetimeRes, Namespace, PartialRes, PerNS, Res};
5656
use rustc_hir::def_id::{LocalDefId, LocalDefIdMap, CRATE_DEF_ID, LOCAL_CRATE};
5757
use rustc_hir::{
58-
self as hir, ConstArg, GenericArg, HirId, ItemLocalMap, MissingLifetimeKind, ParamName,
59-
TraitCandidate,
58+
self as hir, ConstArg, GenericArg, HirId, ItemLocalMap, LangItem, MissingLifetimeKind,
59+
ParamName, TraitCandidate,
6060
};
6161
use rustc_index::{Idx, IndexSlice, IndexVec};
6262
use rustc_macros::extension;
@@ -756,8 +756,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
756756
res
757757
}
758758

759-
fn make_lang_item_qpath(&mut self, lang_item: hir::LangItem, span: Span) -> hir::QPath<'hir> {
760-
hir::QPath::Resolved(None, self.make_lang_item_path(lang_item, span, None))
759+
fn make_lang_item_qpath(
760+
&mut self,
761+
lang_item: hir::LangItem,
762+
span: Span,
763+
args: Option<&'hir hir::GenericArgs<'hir>>,
764+
) -> hir::QPath<'hir> {
765+
hir::QPath::Resolved(None, self.make_lang_item_path(lang_item, span, args))
761766
}
762767

763768
fn make_lang_item_path(
@@ -1300,6 +1305,32 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
13001305
let lifetime = self.lower_lifetime(&region);
13011306
hir::TyKind::Ref(lifetime, self.lower_mt(mt, itctx))
13021307
}
1308+
TyKind::PinnedRef(region, mt) => {
1309+
let region = region.unwrap_or_else(|| {
1310+
let id = if let Some(LifetimeRes::ElidedAnchor { start, end }) =
1311+
self.resolver.get_lifetime_res(t.id)
1312+
{
1313+
debug_assert_eq!(start.plus(1), end);
1314+
start
1315+
} else {
1316+
self.next_node_id()
1317+
};
1318+
let span = self.tcx.sess.source_map().start_point(t.span).shrink_to_hi();
1319+
Lifetime { ident: Ident::new(kw::UnderscoreLifetime, span), id }
1320+
});
1321+
let lifetime = self.lower_lifetime(&region);
1322+
let kind = hir::TyKind::Ref(lifetime, self.lower_mt(mt, itctx));
1323+
let span = self.lower_span(t.span);
1324+
let arg = hir::Ty { kind, span, hir_id: self.next_id() };
1325+
let args = self.arena.alloc(hir::GenericArgs {
1326+
args: self.arena.alloc([hir::GenericArg::Type(self.arena.alloc(arg))]),
1327+
constraints: &[],
1328+
parenthesized: hir::GenericArgsParentheses::No,
1329+
span_ext: span,
1330+
});
1331+
let path = self.make_lang_item_qpath(LangItem::Pin, span, Some(args));
1332+
hir::TyKind::Path(path)
1333+
}
13031334
TyKind::BareFn(f) => {
13041335
let generic_params = self.lower_lifetime_binder(t.id, &f.generic_params);
13051336
hir::TyKind::BareFn(self.arena.alloc(hir::BareFnTy {
@@ -1882,10 +1913,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
18821913
// Given we are only considering `ImplicitSelf` types, we needn't consider
18831914
// the case where we have a mutable pattern to a reference as that would
18841915
// no longer be an `ImplicitSelf`.
1885-
TyKind::Ref(_, mt) if mt.ty.kind.is_implicit_self() => match mt.mutbl {
1886-
hir::Mutability::Not => hir::ImplicitSelfKind::RefImm,
1887-
hir::Mutability::Mut => hir::ImplicitSelfKind::RefMut,
1888-
},
1916+
TyKind::Ref(_, mt) | TyKind::PinnedRef(_, mt)
1917+
if mt.ty.kind.is_implicit_self() =>
1918+
{
1919+
match mt.mutbl {
1920+
hir::Mutability::Not => hir::ImplicitSelfKind::RefImm,
1921+
hir::Mutability::Mut => hir::ImplicitSelfKind::RefMut,
1922+
}
1923+
}
18891924
_ => hir::ImplicitSelfKind::None,
18901925
}
18911926
}),

‎compiler/rustc_ast_lowering/src/lifetime_collector.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -95,7 +95,7 @@ impl<'ast> Visitor<'ast> for LifetimeCollectVisitor<'ast> {
9595
visit::walk_ty(self, t);
9696
self.current_binders.pop();
9797
}
98-
TyKind::Ref(None, _) => {
98+
TyKind::Ref(None, _) | TyKind::PinnedRef(None, _) => {
9999
self.record_elided_anchor(t.id, t.span);
100100
visit::walk_ty(self, t);
101101
}

‎compiler/rustc_ast_passes/src/feature_gate.rs

+1
Original file line numberDiff line numberDiff line change
@@ -545,6 +545,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
545545
gate_all!(mut_ref, "mutable by-reference bindings are experimental");
546546
gate_all!(global_registration, "global registration is experimental");
547547
gate_all!(return_type_notation, "return type notation is experimental");
548+
gate_all!(pin_ergonomics, "pinned reference syntax is experimental");
548549

549550
if !visitor.features.never_patterns {
550551
if let Some(spans) = spans.get(&sym::never_patterns) {

‎compiler/rustc_ast_pretty/src/pprust/state.rs

+6
Original file line numberDiff line numberDiff line change
@@ -1163,6 +1163,12 @@ impl<'a> State<'a> {
11631163
self.print_opt_lifetime(lifetime);
11641164
self.print_mt(mt, false);
11651165
}
1166+
ast::TyKind::PinnedRef(lifetime, mt) => {
1167+
self.word("&");
1168+
self.print_opt_lifetime(lifetime);
1169+
self.word("pin ");
1170+
self.print_mt(mt, true);
1171+
}
11661172
ast::TyKind::Never => {
11671173
self.word("!");
11681174
}

‎compiler/rustc_hir/src/hir.rs

+2-3
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,9 @@
11
use std::fmt;
22

3-
use rustc_ast as ast;
43
use rustc_ast::util::parser::ExprPrecedence;
54
use rustc_ast::{
6-
Attribute, FloatTy, InlineAsmOptions, InlineAsmTemplatePiece, IntTy, Label, LitKind,
7-
TraitObjectSyntax, UintTy,
5+
self as ast, Attribute, FloatTy, InlineAsmOptions, InlineAsmTemplatePiece, IntTy, Label,
6+
LitKind, TraitObjectSyntax, UintTy,
87
};
98
pub use rustc_ast::{
109
BinOp, BinOpKind, BindingMode, BorrowKind, ByRef, CaptureBy, ImplPolarity, IsAuto, Movability,

‎compiler/rustc_parse/src/parser/ty.rs

+36-4
Original file line numberDiff line numberDiff line change
@@ -3,8 +3,9 @@ use rustc_ast::token::{self, BinOpToken, Delimiter, IdentIsRaw, Token, TokenKind
33
use rustc_ast::util::case::Case;
44
use rustc_ast::{
55
self as ast, BareFnTy, BoundAsyncness, BoundConstness, BoundPolarity, FnRetTy, GenericBound,
6-
GenericBounds, GenericParam, Generics, Lifetime, MacCall, MutTy, Mutability, PolyTraitRef,
7-
PreciseCapturingArg, TraitBoundModifiers, TraitObjectSyntax, Ty, TyKind, DUMMY_NODE_ID,
6+
GenericBounds, GenericParam, Generics, Lifetime, MacCall, MutTy, Mutability, Pinnedness,
7+
PolyTraitRef, PreciseCapturingArg, TraitBoundModifiers, TraitObjectSyntax, Ty, TyKind,
8+
DUMMY_NODE_ID,
89
};
910
use rustc_errors::{Applicability, PResult};
1011
use rustc_span::symbol::{kw, sym, Ident};
@@ -529,7 +530,10 @@ impl<'a> Parser<'a> {
529530
fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
530531
let and_span = self.prev_token.span;
531532
let mut opt_lifetime = self.check_lifetime().then(|| self.expect_lifetime());
532-
let mut mutbl = self.parse_mutability();
533+
let (pinned, mut mutbl) = match self.parse_pin_and_mut() {
534+
Some(pin_mut) => pin_mut,
535+
None => (Pinnedness::Not, self.parse_mutability()),
536+
};
533537
if self.token.is_lifetime() && mutbl == Mutability::Mut && opt_lifetime.is_none() {
534538
// A lifetime is invalid here: it would be part of a bare trait bound, which requires
535539
// it to be followed by a plus, but we disallow plus in the pointee type.
@@ -565,7 +569,35 @@ impl<'a> Parser<'a> {
565569
self.bump_with((dyn_tok, dyn_tok_sp));
566570
}
567571
let ty = self.parse_ty_no_plus()?;
568-
Ok(TyKind::Ref(opt_lifetime, MutTy { ty, mutbl }))
572+
Ok(match pinned {
573+
Pinnedness::Not => TyKind::Ref(opt_lifetime, MutTy { ty, mutbl }),
574+
Pinnedness::Pinned => TyKind::PinnedRef(opt_lifetime, MutTy { ty, mutbl }),
575+
})
576+
}
577+
578+
/// Parses `pin` and `mut` annotations on references.
579+
///
580+
/// It must be either `pin const` or `pin mut`.
581+
pub(crate) fn parse_pin_and_mut(&mut self) -> Option<(Pinnedness, Mutability)> {
582+
if self.token.is_ident_named(sym::pin) {
583+
let result = self.look_ahead(1, |token| {
584+
if token.is_keyword(kw::Const) {
585+
Some((Pinnedness::Pinned, Mutability::Not))
586+
} else if token.is_keyword(kw::Mut) {
587+
Some((Pinnedness::Pinned, Mutability::Mut))
588+
} else {
589+
None
590+
}
591+
});
592+
if result.is_some() {
593+
self.psess.gated_spans.gate(sym::pin_ergonomics, self.token.span);
594+
self.bump();
595+
self.bump();
596+
}
597+
result
598+
} else {
599+
None
600+
}
569601
}
570602

571603
// Parses the `typeof(EXPR)`.

‎compiler/rustc_passes/src/hir_stats.rs

+1
Original file line numberDiff line numberDiff line change
@@ -605,6 +605,7 @@ impl<'v> ast_visit::Visitor<'v> for StatCollector<'v> {
605605
Array,
606606
Ptr,
607607
Ref,
608+
PinnedRef,
608609
BareFn,
609610
Never,
610611
Tup,

‎compiler/rustc_resolve/src/late.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -753,7 +753,7 @@ impl<'ra: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'_, 'ast, 'r
753753
let prev = self.diag_metadata.current_trait_object;
754754
let prev_ty = self.diag_metadata.current_type_path;
755755
match &ty.kind {
756-
TyKind::Ref(None, _) => {
756+
TyKind::Ref(None, _) | TyKind::PinnedRef(None, _) => {
757757
// Elided lifetime in reference: we resolve as if there was some lifetime `'_` with
758758
// NodeId `ty.id`.
759759
// This span will be used in case of elision failure.
@@ -2275,7 +2275,7 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
22752275
impl<'ra> Visitor<'ra> for FindReferenceVisitor<'_, '_, '_> {
22762276
fn visit_ty(&mut self, ty: &'ra Ty) {
22772277
trace!("FindReferenceVisitor considering ty={:?}", ty);
2278-
if let TyKind::Ref(lt, _) = ty.kind {
2278+
if let TyKind::Ref(lt, _) | TyKind::PinnedRef(lt, _) = ty.kind {
22792279
// See if anything inside the &thing contains Self
22802280
let mut visitor =
22812281
SelfVisitor { r: self.r, impl_self: self.impl_self, self_found: false };

‎compiler/rustc_resolve/src/late/diagnostics.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -3467,7 +3467,7 @@ struct LifetimeFinder<'ast> {
34673467

34683468
impl<'ast> Visitor<'ast> for LifetimeFinder<'ast> {
34693469
fn visit_ty(&mut self, t: &'ast Ty) {
3470-
if let TyKind::Ref(_, mut_ty) = &t.kind {
3470+
if let TyKind::Ref(_, mut_ty) | TyKind::PinnedRef(_, mut_ty) = &t.kind {
34713471
self.seen.push(t);
34723472
if t.span.lo() == self.lifetime.lo() {
34733473
self.found = Some(&mut_ty.ty);

‎src/tools/clippy/clippy_utils/src/ast_utils.rs

+2-2
Original file line numberDiff line numberDiff line change
@@ -722,8 +722,8 @@ pub fn eq_ty(l: &Ty, r: &Ty) -> bool {
722722
(Slice(l), Slice(r)) => eq_ty(l, r),
723723
(Array(le, ls), Array(re, rs)) => eq_ty(le, re) && eq_expr(&ls.value, &rs.value),
724724
(Ptr(l), Ptr(r)) => l.mutbl == r.mutbl && eq_ty(&l.ty, &r.ty),
725-
(Ref(ll, l), Ref(rl, r)) => {
726-
both(ll, rl, |l, r| eq_id(l.ident, r.ident)) && l.mutbl == r.mutbl && eq_ty(&l.ty, &r.ty)
725+
(Ref(ll, lp, l), Ref(rl, rp, r)) => {
726+
both(ll, rl, |l, r| eq_id(l.ident, r.ident)) && l.mutbl == r.mutbl && eq_ty(&l.ty, &r.ty) && lp == rp
727727
},
728728
(BareFn(l), BareFn(r)) => {
729729
l.safety == r.safety

‎src/tools/rustfmt/src/types.rs

+3-2
Original file line numberDiff line numberDiff line change
@@ -729,7 +729,8 @@ impl Rewrite for ast::Ty {
729729

730730
rewrite_unary_prefix(context, prefix, &*mt.ty, shape)
731731
}
732-
ast::TyKind::Ref(ref lifetime, ref mt) => {
732+
ast::TyKind::Ref(ref lifetime, _pinned, ref mt) => {
733+
// FIXME: format pinnedness
733734
let mut_str = format_mutability(mt.mutbl);
734735
let mut_len = mut_str.len();
735736
let mut result = String::with_capacity(128);
@@ -1143,7 +1144,7 @@ pub(crate) fn can_be_overflowed_type(
11431144
) -> bool {
11441145
match ty.kind {
11451146
ast::TyKind::Tup(..) => context.use_block_indent() && len == 1,
1146-
ast::TyKind::Ref(_, ref mutty) | ast::TyKind::Ptr(ref mutty) => {
1147+
ast::TyKind::Ref(_, _, ref mutty) | ast::TyKind::Ptr(ref mutty) => {
11471148
can_be_overflowed_type(context, &*mutty.ty, len)
11481149
}
11491150
_ => false,

‎tests/ui/async-await/pin-sugar-ambiguity.rs

+15
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
//@ check-pass
2+
#![feature(pin_ergonomics)]
3+
#![allow(dead_code, incomplete_features)]
4+
5+
// Handle the case where there's ambiguity between pin as a contextual keyword and pin as a path.
6+
7+
struct Foo;
8+
9+
mod pin {
10+
pub struct Foo;
11+
}
12+
13+
fn main() {
14+
let _x: &pin ::Foo = &pin::Foo;
15+
}

‎tests/ui/async-await/pin-sugar-no-const.rs

+8
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,8 @@
1+
#![feature(pin_ergonomics)]
2+
#![allow(incomplete_features)]
3+
4+
// Makes sure we don't accidentally accept `&pin Foo` without the `const` keyword.
5+
6+
fn main() {
7+
let _x: &pin i32 = todo!(); //~ ERROR found `i32`
8+
}

‎tests/ui/async-await/pin-sugar-no-const.stderr

+15
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
error: expected one of `!`, `(`, `::`, `;`, `<`, or `=`, found `i32`
2+
--> $DIR/pin-sugar-no-const.rs:7:18
3+
|
4+
LL | let _x: &pin i32 = todo!();
5+
| - ^^^ expected one of `!`, `(`, `::`, `;`, `<`, or `=`
6+
| |
7+
| while parsing the type for `_x`
8+
|
9+
help: there is a keyword `in` with a similar name
10+
|
11+
LL | let _x: &in i32 = todo!();
12+
| ~~
13+
14+
error: aborting due to 1 previous error
15+

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