1 use crate::def::{DefKind, Namespace, Res};
2 use crate::def_id::DefId;
3 crate use crate::hir_id::HirId;
4 use crate::{itemlikevisit, LangItem};
6 use rustc_ast::util::parser::ExprPrecedence;
7 use rustc_ast::{self as ast, CrateSugar, LlvmAsmDialect};
8 use rustc_ast::{AttrVec, Attribute, FloatTy, IntTy, Label, LitKind, StrStyle, UintTy};
9 pub use rustc_ast::{BorrowKind, ImplPolarity, IsAuto};
10 pub use rustc_ast::{CaptureBy, Movability, Mutability};
11 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
12 use rustc_data_structures::sync::{par_for_each_in, Send, Sync};
13 use rustc_macros::HashStable_Generic;
14 use rustc_span::source_map::{SourceMap, Spanned};
15 use rustc_span::symbol::{kw, sym, Ident, Symbol};
16 use rustc_span::{def_id::LocalDefId, BytePos};
17 use rustc_span::{MultiSpan, Span, DUMMY_SP};
18 use rustc_target::asm::InlineAsmRegOrRegClass;
19 use rustc_target::spec::abi::Abi;
21 use smallvec::SmallVec;
22 use std::collections::{BTreeMap, BTreeSet};
25 #[derive(Copy, Clone, Encodable, HashStable_Generic)]
30 /// Either "`'a`", referring to a named lifetime definition,
31 /// or "``" (i.e., `kw::Empty`), for elision placeholders.
33 /// HIR lowering inserts these placeholders in type paths that
34 /// refer to type definitions needing lifetime parameters,
35 /// `&T` and `&mut T`, and trait objects without `... + 'a`.
36 pub name: LifetimeName,
39 #[derive(Debug, Clone, PartialEq, Eq, Encodable, Hash, Copy)]
40 #[derive(HashStable_Generic)]
42 /// Some user-given name like `T` or `'x`.
45 /// Synthetic name generated when user elided a lifetime in an impl header.
47 /// E.g., the lifetimes in cases like these:
50 /// impl Foo<'_> for u32
52 /// in that case, we rewrite to
54 /// impl<'f> Foo for &'f u32
55 /// impl<'f> Foo<'f> for u32
57 /// where `'f` is something like `Fresh(0)`. The indices are
58 /// unique per impl, but not necessarily continuous.
61 /// Indicates an illegal name was given and an error has been
62 /// reported (so we should squelch other derived errors). Occurs
63 /// when, e.g., `'_` is used in the wrong place.
68 pub fn ident(&self) -> Ident {
70 ParamName::Plain(ident) => ident,
71 ParamName::Fresh(_) | ParamName::Error => {
72 Ident::with_dummy_span(kw::UnderscoreLifetime)
77 pub fn normalize_to_macros_2_0(&self) -> ParamName {
79 ParamName::Plain(ident) => ParamName::Plain(ident.normalize_to_macros_2_0()),
80 param_name => param_name,
85 #[derive(Debug, Clone, PartialEq, Eq, Encodable, Hash, Copy)]
86 #[derive(HashStable_Generic)]
87 pub enum LifetimeName {
88 /// User-given names or fresh (synthetic) names.
91 /// User wrote nothing (e.g., the lifetime in `&u32`).
94 /// Implicit lifetime in a context like `dyn Foo`. This is
95 /// distinguished from implicit lifetimes elsewhere because the
96 /// lifetime that they default to must appear elsewhere within the
97 /// enclosing type. This means that, in an `impl Trait` context, we
98 /// don't have to create a parameter for them. That is, `impl
99 /// Trait<Item = &u32>` expands to an opaque type like `type
100 /// Foo<'a> = impl Trait<Item = &'a u32>`, but `impl Trait<item =
101 /// dyn Bar>` expands to `type Foo = impl Trait<Item = dyn Bar +
102 /// 'static>`. The latter uses `ImplicitObjectLifetimeDefault` so
103 /// that surrounding code knows not to create a lifetime
105 ImplicitObjectLifetimeDefault,
107 /// Indicates an error during lowering (usually `'_` in wrong place)
108 /// that was already reported.
111 /// User wrote specifies `'_`.
114 /// User wrote `'static`.
119 pub fn ident(&self) -> Ident {
121 LifetimeName::ImplicitObjectLifetimeDefault
122 | LifetimeName::Implicit
123 | LifetimeName::Error => Ident::invalid(),
124 LifetimeName::Underscore => Ident::with_dummy_span(kw::UnderscoreLifetime),
125 LifetimeName::Static => Ident::with_dummy_span(kw::StaticLifetime),
126 LifetimeName::Param(param_name) => param_name.ident(),
130 pub fn is_elided(&self) -> bool {
132 LifetimeName::ImplicitObjectLifetimeDefault
133 | LifetimeName::Implicit
134 | LifetimeName::Underscore => true,
136 // It might seem surprising that `Fresh(_)` counts as
137 // *not* elided -- but this is because, as far as the code
138 // in the compiler is concerned -- `Fresh(_)` variants act
139 // equivalently to "some fresh name". They correspond to
140 // early-bound regions on an impl, in other words.
141 LifetimeName::Error | LifetimeName::Param(_) | LifetimeName::Static => false,
145 fn is_static(&self) -> bool {
146 self == &LifetimeName::Static
149 pub fn normalize_to_macros_2_0(&self) -> LifetimeName {
151 LifetimeName::Param(param_name) => {
152 LifetimeName::Param(param_name.normalize_to_macros_2_0())
154 lifetime_name => lifetime_name,
159 impl fmt::Display for Lifetime {
160 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
161 self.name.ident().fmt(f)
165 impl fmt::Debug for Lifetime {
166 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
167 write!(f, "lifetime({}: {})", self.hir_id, self.name.ident())
172 pub fn is_elided(&self) -> bool {
173 self.name.is_elided()
176 pub fn is_static(&self) -> bool {
177 self.name.is_static()
181 /// A `Path` is essentially Rust's notion of a name; for instance,
182 /// `std::cmp::PartialEq`. It's represented as a sequence of identifiers,
183 /// along with a bunch of supporting information.
184 #[derive(Debug, HashStable_Generic)]
185 pub struct Path<'hir> {
187 /// The resolution for the path.
189 /// The segments in the path: the things separated by `::`.
190 pub segments: &'hir [PathSegment<'hir>],
194 pub fn is_global(&self) -> bool {
195 !self.segments.is_empty() && self.segments[0].ident.name == kw::PathRoot
199 /// A segment of a path: an identifier, an optional lifetime, and a set of
201 #[derive(Debug, HashStable_Generic)]
202 pub struct PathSegment<'hir> {
203 /// The identifier portion of this path segment.
204 #[stable_hasher(project(name))]
206 // `id` and `res` are optional. We currently only use these in save-analysis,
207 // any path segments without these will not have save-analysis info and
208 // therefore will not have 'jump to def' in IDEs, but otherwise will not be
209 // affected. (In general, we don't bother to get the defs for synthesized
210 // segments, only for segments which have come from the AST).
211 pub hir_id: Option<HirId>,
212 pub res: Option<Res>,
214 /// Type/lifetime parameters attached to this path. They come in
215 /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`. Note that
216 /// this is more than just simple syntactic sugar; the use of
217 /// parens affects the region binding rules, so we preserve the
219 pub args: Option<&'hir GenericArgs<'hir>>,
221 /// Whether to infer remaining type parameters, if any.
222 /// This only applies to expression and pattern paths, and
223 /// out of those only the segments with no type parameters
224 /// to begin with, e.g., `Vec::new` is `<Vec<..>>::new::<..>`.
225 pub infer_args: bool,
228 impl<'hir> PathSegment<'hir> {
229 /// Converts an identifier to the corresponding segment.
230 pub fn from_ident(ident: Ident) -> PathSegment<'hir> {
231 PathSegment { ident, hir_id: None, res: None, infer_args: true, args: None }
234 pub fn invalid() -> Self {
235 Self::from_ident(Ident::invalid())
238 pub fn args(&self) -> &GenericArgs<'hir> {
239 if let Some(ref args) = self.args {
242 const DUMMY: &GenericArgs<'_> = &GenericArgs::none();
248 #[derive(Encodable, Debug, HashStable_Generic)]
249 pub struct ConstArg {
250 pub value: AnonConst,
254 #[derive(Debug, HashStable_Generic)]
255 pub enum GenericArg<'hir> {
261 impl GenericArg<'_> {
262 pub fn span(&self) -> Span {
264 GenericArg::Lifetime(l) => l.span,
265 GenericArg::Type(t) => t.span,
266 GenericArg::Const(c) => c.span,
270 pub fn id(&self) -> HirId {
272 GenericArg::Lifetime(l) => l.hir_id,
273 GenericArg::Type(t) => t.hir_id,
274 GenericArg::Const(c) => c.value.hir_id,
278 pub fn is_const(&self) -> bool {
279 matches!(self, GenericArg::Const(_))
282 pub fn is_synthetic(&self) -> bool {
283 matches!(self, GenericArg::Lifetime(lifetime) if lifetime.name.ident() == Ident::invalid())
286 pub fn descr(&self) -> &'static str {
288 GenericArg::Lifetime(_) => "lifetime",
289 GenericArg::Type(_) => "type",
290 GenericArg::Const(_) => "constant",
294 pub fn to_ord(&self, feats: &rustc_feature::Features) -> ast::ParamKindOrd {
296 GenericArg::Lifetime(_) => ast::ParamKindOrd::Lifetime,
297 GenericArg::Type(_) => ast::ParamKindOrd::Type,
298 GenericArg::Const(_) => ast::ParamKindOrd::Const { unordered: feats.const_generics },
303 #[derive(Debug, HashStable_Generic)]
304 pub struct GenericArgs<'hir> {
305 /// The generic arguments for this path segment.
306 pub args: &'hir [GenericArg<'hir>],
307 /// Bindings (equality constraints) on associated types, if present.
308 /// E.g., `Foo<A = Bar>`.
309 pub bindings: &'hir [TypeBinding<'hir>],
310 /// Were arguments written in parenthesized form `Fn(T) -> U`?
311 /// This is required mostly for pretty-printing and diagnostics,
312 /// but also for changing lifetime elision rules to be "function-like".
313 pub parenthesized: bool,
316 impl GenericArgs<'_> {
317 pub const fn none() -> Self {
318 Self { args: &[], bindings: &[], parenthesized: false }
321 pub fn inputs(&self) -> &[Ty<'_>] {
322 if self.parenthesized {
323 for arg in self.args {
325 GenericArg::Lifetime(_) => {}
326 GenericArg::Type(ref ty) => {
327 if let TyKind::Tup(ref tys) = ty.kind {
332 GenericArg::Const(_) => {}
336 panic!("GenericArgs::inputs: not a `Fn(T) -> U`");
339 pub fn own_counts(&self) -> GenericParamCount {
340 // We could cache this as a property of `GenericParamCount`, but
341 // the aim is to refactor this away entirely eventually and the
342 // presence of this method will be a constant reminder.
343 let mut own_counts: GenericParamCount = Default::default();
345 for arg in self.args {
347 GenericArg::Lifetime(_) => own_counts.lifetimes += 1,
348 GenericArg::Type(_) => own_counts.types += 1,
349 GenericArg::Const(_) => own_counts.consts += 1,
356 pub fn span(&self) -> Option<Span> {
359 .filter(|arg| !arg.is_synthetic())
360 .map(|arg| arg.span())
361 .reduce(|span1, span2| span1.to(span2))
364 /// Returns span encompassing arguments and their surrounding `<>` or `()`
365 pub fn span_ext(&self, sm: &SourceMap) -> Option<Span> {
366 let mut span = self.span()?;
368 let (o, c) = if self.parenthesized { ('(', ')') } else { ('<', '>') };
370 if let Ok(snippet) = sm.span_to_snippet(span) {
371 let snippet = snippet.as_bytes();
373 if snippet[0] != (o as u8) || snippet[snippet.len() - 1] != (c as u8) {
374 span = sm.span_extend_to_prev_char(span, o, true);
375 span = span.with_lo(span.lo() - BytePos(1));
377 span = sm.span_extend_to_next_char(span, c, true);
378 span = span.with_hi(span.hi() + BytePos(1));
385 pub fn is_empty(&self) -> bool {
390 /// A modifier on a bound, currently this is only used for `?Sized`, where the
391 /// modifier is `Maybe`. Negative bounds should also be handled here.
392 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Hash, Debug)]
393 #[derive(HashStable_Generic)]
394 pub enum TraitBoundModifier {
400 /// The AST represents all type param bounds as types.
401 /// `typeck::collect::compute_bounds` matches these against
402 /// the "special" built-in traits (see `middle::lang_items`) and
403 /// detects `Copy`, `Send` and `Sync`.
404 #[derive(Debug, HashStable_Generic)]
405 pub enum GenericBound<'hir> {
406 Trait(PolyTraitRef<'hir>, TraitBoundModifier),
407 // FIXME(davidtwco): Introduce `PolyTraitRef::LangItem`
408 LangItemTrait(LangItem, Span, HirId, &'hir GenericArgs<'hir>),
412 impl GenericBound<'_> {
413 pub fn trait_ref(&self) -> Option<&TraitRef<'_>> {
415 GenericBound::Trait(data, _) => Some(&data.trait_ref),
420 pub fn span(&self) -> Span {
422 GenericBound::Trait(t, ..) => t.span,
423 GenericBound::LangItemTrait(_, span, ..) => *span,
424 GenericBound::Outlives(l) => l.span,
429 pub type GenericBounds<'hir> = &'hir [GenericBound<'hir>];
431 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Debug, HashStable_Generic)]
432 pub enum LifetimeParamKind {
433 // Indicates that the lifetime definition was explicitly declared (e.g., in
434 // `fn foo<'a>(x: &'a u8) -> &'a u8 { x }`).
437 // Indicates that the lifetime definition was synthetically added
438 // as a result of an in-band lifetime usage (e.g., in
439 // `fn foo(x: &'a u8) -> &'a u8 { x }`).
442 // Indication that the lifetime was elided (e.g., in both cases in
443 // `fn foo(x: &u8) -> &'_ u8 { x }`).
446 // Indication that the lifetime name was somehow in error.
450 #[derive(Debug, HashStable_Generic)]
451 pub enum GenericParamKind<'hir> {
452 /// A lifetime definition (e.g., `'a: 'b + 'c + 'd`).
454 kind: LifetimeParamKind,
457 default: Option<&'hir Ty<'hir>>,
458 synthetic: Option<SyntheticTyParamKind>,
462 /// Optional default value for the const generic param
463 default: Option<AnonConst>,
467 #[derive(Debug, HashStable_Generic)]
468 pub struct GenericParam<'hir> {
471 pub attrs: &'hir [Attribute],
472 pub bounds: GenericBounds<'hir>,
474 pub pure_wrt_drop: bool,
475 pub kind: GenericParamKind<'hir>,
478 impl GenericParam<'hir> {
479 pub fn bounds_span(&self) -> Option<Span> {
480 self.bounds.iter().fold(None, |span, bound| {
481 let span = span.map(|s| s.to(bound.span())).unwrap_or_else(|| bound.span());
489 pub struct GenericParamCount {
490 pub lifetimes: usize,
495 /// Represents lifetimes and type parameters attached to a declaration
496 /// of a function, enum, trait, etc.
497 #[derive(Debug, HashStable_Generic)]
498 pub struct Generics<'hir> {
499 pub params: &'hir [GenericParam<'hir>],
500 pub where_clause: WhereClause<'hir>,
504 impl Generics<'hir> {
505 pub const fn empty() -> Generics<'hir> {
508 where_clause: WhereClause { predicates: &[], span: DUMMY_SP },
513 pub fn get_named(&self, name: Symbol) -> Option<&GenericParam<'_>> {
514 for param in self.params {
515 if name == param.name.ident().name {
522 pub fn spans(&self) -> MultiSpan {
523 if self.params.is_empty() {
526 self.params.iter().map(|p| p.span).collect::<Vec<Span>>().into()
531 /// Synthetic type parameters are converted to another form during lowering; this allows
532 /// us to track the original form they had, and is useful for error messages.
533 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
534 #[derive(HashStable_Generic)]
535 pub enum SyntheticTyParamKind {
537 // Created by the `#[rustc_synthetic]` attribute.
541 /// A where-clause in a definition.
542 #[derive(Debug, HashStable_Generic)]
543 pub struct WhereClause<'hir> {
544 pub predicates: &'hir [WherePredicate<'hir>],
545 // Only valid if predicates aren't empty.
549 impl WhereClause<'_> {
550 pub fn span(&self) -> Option<Span> {
551 if self.predicates.is_empty() { None } else { Some(self.span) }
554 /// The `WhereClause` under normal circumstances points at either the predicates or the empty
555 /// space where the `where` clause should be. Only of use for diagnostic suggestions.
556 pub fn span_for_predicates_or_empty_place(&self) -> Span {
560 /// `Span` where further predicates would be suggested, accounting for trailing commas, like
561 /// in `fn foo<T>(t: T) where T: Foo,` so we don't suggest two trailing commas.
562 pub fn tail_span_for_suggestion(&self) -> Span {
563 let end = self.span_for_predicates_or_empty_place().shrink_to_hi();
564 self.predicates.last().map_or(end, |p| p.span()).shrink_to_hi().to(end)
568 /// A single predicate in a where-clause.
569 #[derive(Debug, HashStable_Generic)]
570 pub enum WherePredicate<'hir> {
571 /// A type binding (e.g., `for<'c> Foo: Send + Clone + 'c`).
572 BoundPredicate(WhereBoundPredicate<'hir>),
573 /// A lifetime predicate (e.g., `'a: 'b + 'c`).
574 RegionPredicate(WhereRegionPredicate<'hir>),
575 /// An equality predicate (unsupported).
576 EqPredicate(WhereEqPredicate<'hir>),
579 impl WherePredicate<'_> {
580 pub fn span(&self) -> Span {
582 WherePredicate::BoundPredicate(p) => p.span,
583 WherePredicate::RegionPredicate(p) => p.span,
584 WherePredicate::EqPredicate(p) => p.span,
589 /// A type bound (e.g., `for<'c> Foo: Send + Clone + 'c`).
590 #[derive(Debug, HashStable_Generic)]
591 pub struct WhereBoundPredicate<'hir> {
593 /// Any generics from a `for` binding.
594 pub bound_generic_params: &'hir [GenericParam<'hir>],
595 /// The type being bounded.
596 pub bounded_ty: &'hir Ty<'hir>,
597 /// Trait and lifetime bounds (e.g., `Clone + Send + 'static`).
598 pub bounds: GenericBounds<'hir>,
601 /// A lifetime predicate (e.g., `'a: 'b + 'c`).
602 #[derive(Debug, HashStable_Generic)]
603 pub struct WhereRegionPredicate<'hir> {
605 pub lifetime: Lifetime,
606 pub bounds: GenericBounds<'hir>,
609 /// An equality predicate (e.g., `T = int`); currently unsupported.
610 #[derive(Debug, HashStable_Generic)]
611 pub struct WhereEqPredicate<'hir> {
614 pub lhs_ty: &'hir Ty<'hir>,
615 pub rhs_ty: &'hir Ty<'hir>,
618 #[derive(Encodable, Debug, HashStable_Generic)]
619 pub struct ModuleItems {
620 // Use BTreeSets here so items are in the same order as in the
621 // list of all items in Crate
622 pub items: BTreeSet<HirId>,
623 pub trait_items: BTreeSet<TraitItemId>,
624 pub impl_items: BTreeSet<ImplItemId>,
625 pub foreign_items: BTreeSet<ForeignItemId>,
628 /// A type representing only the top-level module.
629 #[derive(Encodable, Debug, HashStable_Generic)]
630 pub struct CrateItem<'hir> {
631 pub module: Mod<'hir>,
632 pub attrs: &'hir [Attribute],
636 /// The top-level data structure that stores the entire contents of
637 /// the crate currently being compiled.
639 /// For more details, see the [rustc dev guide].
641 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html
643 pub struct Crate<'hir> {
644 pub item: CrateItem<'hir>,
645 pub exported_macros: &'hir [MacroDef<'hir>],
646 // Attributes from non-exported macros, kept only for collecting the library feature list.
647 pub non_exported_macro_attrs: &'hir [Attribute],
649 // N.B., we use a `BTreeMap` here so that `visit_all_items` iterates
650 // over the ids in increasing order. In principle it should not
651 // matter what order we visit things in, but in *practice* it
652 // does, because it can affect the order in which errors are
653 // detected, which in turn can make UI tests yield
654 // slightly different results.
655 pub items: BTreeMap<HirId, Item<'hir>>,
657 pub trait_items: BTreeMap<TraitItemId, TraitItem<'hir>>,
658 pub impl_items: BTreeMap<ImplItemId, ImplItem<'hir>>,
659 pub foreign_items: BTreeMap<ForeignItemId, ForeignItem<'hir>>,
660 pub bodies: BTreeMap<BodyId, Body<'hir>>,
661 pub trait_impls: BTreeMap<DefId, Vec<HirId>>,
663 /// A list of the body ids written out in the order in which they
664 /// appear in the crate. If you're going to process all the bodies
665 /// in the crate, you should iterate over this list rather than the keys
667 pub body_ids: Vec<BodyId>,
669 /// A list of modules written out in the order in which they
670 /// appear in the crate. This includes the main crate module.
671 pub modules: BTreeMap<HirId, ModuleItems>,
672 /// A list of proc macro HirIds, written out in the order in which
673 /// they are declared in the static array generated by proc_macro_harness.
674 pub proc_macros: Vec<HirId>,
676 pub trait_map: BTreeMap<HirId, Vec<TraitCandidate>>,
680 pub fn item(&self, id: HirId) -> &Item<'hir> {
684 pub fn trait_item(&self, id: TraitItemId) -> &TraitItem<'hir> {
685 &self.trait_items[&id]
688 pub fn impl_item(&self, id: ImplItemId) -> &ImplItem<'hir> {
689 &self.impl_items[&id]
692 pub fn foreign_item(&self, id: ForeignItemId) -> &ForeignItem<'hir> {
693 &self.foreign_items[&id]
696 pub fn body(&self, id: BodyId) -> &Body<'hir> {
702 /// Visits all items in the crate in some deterministic (but
703 /// unspecified) order. If you just need to process every item,
704 /// but don't care about nesting, this method is the best choice.
706 /// If you do care about nesting -- usually because your algorithm
707 /// follows lexical scoping rules -- then you want a different
708 /// approach. You should override `visit_nested_item` in your
709 /// visitor and then call `intravisit::walk_crate` instead.
710 pub fn visit_all_item_likes<'hir, V>(&'hir self, visitor: &mut V)
712 V: itemlikevisit::ItemLikeVisitor<'hir>,
714 for item in self.items.values() {
715 visitor.visit_item(item);
718 for trait_item in self.trait_items.values() {
719 visitor.visit_trait_item(trait_item);
722 for impl_item in self.impl_items.values() {
723 visitor.visit_impl_item(impl_item);
726 for foreign_item in self.foreign_items.values() {
727 visitor.visit_foreign_item(foreign_item);
731 /// A parallel version of `visit_all_item_likes`.
732 pub fn par_visit_all_item_likes<'hir, V>(&'hir self, visitor: &V)
734 V: itemlikevisit::ParItemLikeVisitor<'hir> + Sync + Send,
738 par_for_each_in(&self.items, |(_, item)| {
739 visitor.visit_item(item);
743 par_for_each_in(&self.trait_items, |(_, trait_item)| {
744 visitor.visit_trait_item(trait_item);
748 par_for_each_in(&self.impl_items, |(_, impl_item)| {
749 visitor.visit_impl_item(impl_item);
753 par_for_each_in(&self.foreign_items, |(_, foreign_item)| {
754 visitor.visit_foreign_item(foreign_item);
761 /// A macro definition, in this crate or imported from another.
763 /// Not parsed directly, but created on macro import or `macro_rules!` expansion.
764 #[derive(Debug, HashStable_Generic)]
765 pub struct MacroDef<'hir> {
767 pub vis: Visibility<'hir>,
768 pub attrs: &'hir [Attribute],
771 pub ast: ast::MacroDef,
774 /// A block of statements `{ .. }`, which may have a label (in this case the
775 /// `targeted_by_break` field will be `true`) and may be `unsafe` by means of
776 /// the `rules` being anything but `DefaultBlock`.
777 #[derive(Debug, HashStable_Generic)]
778 pub struct Block<'hir> {
779 /// Statements in a block.
780 pub stmts: &'hir [Stmt<'hir>],
781 /// An expression at the end of the block
782 /// without a semicolon, if any.
783 pub expr: Option<&'hir Expr<'hir>>,
784 #[stable_hasher(ignore)]
786 /// Distinguishes between `unsafe { ... }` and `{ ... }`.
787 pub rules: BlockCheckMode,
789 /// If true, then there may exist `break 'a` values that aim to
790 /// break out of this block early.
791 /// Used by `'label: {}` blocks and by `try {}` blocks.
792 pub targeted_by_break: bool,
795 #[derive(Debug, HashStable_Generic)]
796 pub struct Pat<'hir> {
797 #[stable_hasher(ignore)]
799 pub kind: PatKind<'hir>,
801 // Whether to use default binding modes.
802 // At present, this is false only for destructuring assignment.
803 pub default_binding_modes: bool,
806 impl<'hir> Pat<'hir> {
807 // FIXME(#19596) this is a workaround, but there should be a better way
808 fn walk_short_(&self, it: &mut impl FnMut(&Pat<'hir>) -> bool) -> bool {
815 Wild | Lit(_) | Range(..) | Binding(.., None) | Path(_) => true,
816 Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_short_(it),
817 Struct(_, fields, _) => fields.iter().all(|field| field.pat.walk_short_(it)),
818 TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().all(|p| p.walk_short_(it)),
819 Slice(before, slice, after) => {
820 before.iter().chain(slice.iter()).chain(after.iter()).all(|p| p.walk_short_(it))
825 /// Walk the pattern in left-to-right order,
826 /// short circuiting (with `.all(..)`) if `false` is returned.
828 /// Note that when visiting e.g. `Tuple(ps)`,
829 /// if visiting `ps[0]` returns `false`,
830 /// then `ps[1]` will not be visited.
831 pub fn walk_short(&self, mut it: impl FnMut(&Pat<'hir>) -> bool) -> bool {
832 self.walk_short_(&mut it)
835 // FIXME(#19596) this is a workaround, but there should be a better way
836 fn walk_(&self, it: &mut impl FnMut(&Pat<'hir>) -> bool) {
843 Wild | Lit(_) | Range(..) | Binding(.., None) | Path(_) => {}
844 Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_(it),
845 Struct(_, fields, _) => fields.iter().for_each(|field| field.pat.walk_(it)),
846 TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().for_each(|p| p.walk_(it)),
847 Slice(before, slice, after) => {
848 before.iter().chain(slice.iter()).chain(after.iter()).for_each(|p| p.walk_(it))
853 /// Walk the pattern in left-to-right order.
855 /// If `it(pat)` returns `false`, the children are not visited.
856 pub fn walk(&self, mut it: impl FnMut(&Pat<'hir>) -> bool) {
860 /// Walk the pattern in left-to-right order.
862 /// If you always want to recurse, prefer this method over `walk`.
863 pub fn walk_always(&self, mut it: impl FnMut(&Pat<'_>)) {
871 /// A single field in a struct pattern.
873 /// Patterns like the fields of Foo `{ x, ref y, ref mut z }`
874 /// are treated the same as` x: x, y: ref y, z: ref mut z`,
875 /// except `is_shorthand` is true.
876 #[derive(Debug, HashStable_Generic)]
877 pub struct FieldPat<'hir> {
878 #[stable_hasher(ignore)]
880 /// The identifier for the field.
881 #[stable_hasher(project(name))]
883 /// The pattern the field is destructured to.
884 pub pat: &'hir Pat<'hir>,
885 pub is_shorthand: bool,
889 /// Explicit binding annotations given in the HIR for a binding. Note
890 /// that this is not the final binding *mode* that we infer after type
892 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
893 pub enum BindingAnnotation {
894 /// No binding annotation given: this means that the final binding mode
895 /// will depend on whether we have skipped through a `&` reference
896 /// when matching. For example, the `x` in `Some(x)` will have binding
897 /// mode `None`; if you do `let Some(x) = &Some(22)`, it will
898 /// ultimately be inferred to be by-reference.
900 /// Note that implicit reference skipping is not implemented yet (#42640).
903 /// Annotated with `mut x` -- could be either ref or not, similar to `None`.
906 /// Annotated as `ref`, like `ref x`
909 /// Annotated as `ref mut x`.
913 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
919 impl fmt::Display for RangeEnd {
920 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
921 f.write_str(match self {
922 RangeEnd::Included => "..=",
923 RangeEnd::Excluded => "..",
928 #[derive(Debug, HashStable_Generic)]
929 pub enum PatKind<'hir> {
930 /// Represents a wildcard pattern (i.e., `_`).
933 /// A fresh binding `ref mut binding @ OPT_SUBPATTERN`.
934 /// The `HirId` is the canonical ID for the variable being bound,
935 /// (e.g., in `Ok(x) | Err(x)`, both `x` use the same canonical ID),
936 /// which is the pattern ID of the first `x`.
937 Binding(BindingAnnotation, HirId, Ident, Option<&'hir Pat<'hir>>),
939 /// A struct or struct variant pattern (e.g., `Variant {x, y, ..}`).
940 /// The `bool` is `true` in the presence of a `..`.
941 Struct(QPath<'hir>, &'hir [FieldPat<'hir>], bool),
943 /// A tuple struct/variant pattern `Variant(x, y, .., z)`.
944 /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
945 /// `0 <= position <= subpats.len()`
946 TupleStruct(QPath<'hir>, &'hir [&'hir Pat<'hir>], Option<usize>),
948 /// An or-pattern `A | B | C`.
949 /// Invariant: `pats.len() >= 2`.
950 Or(&'hir [&'hir Pat<'hir>]),
952 /// A path pattern for an unit struct/variant or a (maybe-associated) constant.
955 /// A tuple pattern (e.g., `(a, b)`).
956 /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
957 /// `0 <= position <= subpats.len()`
958 Tuple(&'hir [&'hir Pat<'hir>], Option<usize>),
961 Box(&'hir Pat<'hir>),
963 /// A reference pattern (e.g., `&mut (a, b)`).
964 Ref(&'hir Pat<'hir>, Mutability),
967 Lit(&'hir Expr<'hir>),
969 /// A range pattern (e.g., `1..=2` or `1..2`).
970 Range(Option<&'hir Expr<'hir>>, Option<&'hir Expr<'hir>>, RangeEnd),
972 /// A slice pattern, `[before_0, ..., before_n, (slice, after_0, ..., after_n)?]`.
974 /// Here, `slice` is lowered from the syntax `($binding_mode $ident @)? ..`.
975 /// If `slice` exists, then `after` can be non-empty.
977 /// The representation for e.g., `[a, b, .., c, d]` is:
979 /// PatKind::Slice([Binding(a), Binding(b)], Some(Wild), [Binding(c), Binding(d)])
981 Slice(&'hir [&'hir Pat<'hir>], Option<&'hir Pat<'hir>>, &'hir [&'hir Pat<'hir>]),
984 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
986 /// The `+` operator (addition).
988 /// The `-` operator (subtraction).
990 /// The `*` operator (multiplication).
992 /// The `/` operator (division).
994 /// The `%` operator (modulus).
996 /// The `&&` operator (logical and).
998 /// The `||` operator (logical or).
1000 /// The `^` operator (bitwise xor).
1002 /// The `&` operator (bitwise and).
1004 /// The `|` operator (bitwise or).
1006 /// The `<<` operator (shift left).
1008 /// The `>>` operator (shift right).
1010 /// The `==` operator (equality).
1012 /// The `<` operator (less than).
1014 /// The `<=` operator (less than or equal to).
1016 /// The `!=` operator (not equal to).
1018 /// The `>=` operator (greater than or equal to).
1020 /// The `>` operator (greater than).
1025 pub fn as_str(self) -> &'static str {
1027 BinOpKind::Add => "+",
1028 BinOpKind::Sub => "-",
1029 BinOpKind::Mul => "*",
1030 BinOpKind::Div => "/",
1031 BinOpKind::Rem => "%",
1032 BinOpKind::And => "&&",
1033 BinOpKind::Or => "||",
1034 BinOpKind::BitXor => "^",
1035 BinOpKind::BitAnd => "&",
1036 BinOpKind::BitOr => "|",
1037 BinOpKind::Shl => "<<",
1038 BinOpKind::Shr => ">>",
1039 BinOpKind::Eq => "==",
1040 BinOpKind::Lt => "<",
1041 BinOpKind::Le => "<=",
1042 BinOpKind::Ne => "!=",
1043 BinOpKind::Ge => ">=",
1044 BinOpKind::Gt => ">",
1048 pub fn is_lazy(self) -> bool {
1049 matches!(self, BinOpKind::And | BinOpKind::Or)
1052 pub fn is_shift(self) -> bool {
1053 matches!(self, BinOpKind::Shl | BinOpKind::Shr)
1056 pub fn is_comparison(self) -> bool {
1063 | BinOpKind::Ge => true,
1075 | BinOpKind::Shr => false,
1079 /// Returns `true` if the binary operator takes its arguments by value.
1080 pub fn is_by_value(self) -> bool {
1081 !self.is_comparison()
1085 impl Into<ast::BinOpKind> for BinOpKind {
1086 fn into(self) -> ast::BinOpKind {
1088 BinOpKind::Add => ast::BinOpKind::Add,
1089 BinOpKind::Sub => ast::BinOpKind::Sub,
1090 BinOpKind::Mul => ast::BinOpKind::Mul,
1091 BinOpKind::Div => ast::BinOpKind::Div,
1092 BinOpKind::Rem => ast::BinOpKind::Rem,
1093 BinOpKind::And => ast::BinOpKind::And,
1094 BinOpKind::Or => ast::BinOpKind::Or,
1095 BinOpKind::BitXor => ast::BinOpKind::BitXor,
1096 BinOpKind::BitAnd => ast::BinOpKind::BitAnd,
1097 BinOpKind::BitOr => ast::BinOpKind::BitOr,
1098 BinOpKind::Shl => ast::BinOpKind::Shl,
1099 BinOpKind::Shr => ast::BinOpKind::Shr,
1100 BinOpKind::Eq => ast::BinOpKind::Eq,
1101 BinOpKind::Lt => ast::BinOpKind::Lt,
1102 BinOpKind::Le => ast::BinOpKind::Le,
1103 BinOpKind::Ne => ast::BinOpKind::Ne,
1104 BinOpKind::Ge => ast::BinOpKind::Ge,
1105 BinOpKind::Gt => ast::BinOpKind::Gt,
1110 pub type BinOp = Spanned<BinOpKind>;
1112 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
1114 /// The `*` operator (deferencing).
1116 /// The `!` operator (logical negation).
1118 /// The `-` operator (negation).
1123 pub fn as_str(self) -> &'static str {
1131 /// Returns `true` if the unary operator takes its argument by value.
1132 pub fn is_by_value(self) -> bool {
1133 matches!(self, Self::Neg | Self::Not)
1138 #[derive(Debug, HashStable_Generic)]
1139 pub struct Stmt<'hir> {
1141 pub kind: StmtKind<'hir>,
1145 /// The contents of a statement.
1146 #[derive(Debug, HashStable_Generic)]
1147 pub enum StmtKind<'hir> {
1148 /// A local (`let`) binding.
1149 Local(&'hir Local<'hir>),
1151 /// An item binding.
1154 /// An expression without a trailing semi-colon (must have unit type).
1155 Expr(&'hir Expr<'hir>),
1157 /// An expression with a trailing semi-colon (may have any type).
1158 Semi(&'hir Expr<'hir>),
1161 impl<'hir> StmtKind<'hir> {
1162 pub fn attrs(&self, get_item: impl FnOnce(ItemId) -> &'hir Item<'hir>) -> &'hir [Attribute] {
1164 StmtKind::Local(ref l) => &l.attrs,
1165 StmtKind::Item(ref item_id) => &get_item(*item_id).attrs,
1166 StmtKind::Expr(ref e) | StmtKind::Semi(ref e) => &e.attrs,
1171 /// Represents a `let` statement (i.e., `let <pat>:<ty> = <expr>;`).
1172 #[derive(Debug, HashStable_Generic)]
1173 pub struct Local<'hir> {
1174 pub pat: &'hir Pat<'hir>,
1175 /// Type annotation, if any (otherwise the type will be inferred).
1176 pub ty: Option<&'hir Ty<'hir>>,
1177 /// Initializer expression to set the value, if any.
1178 pub init: Option<&'hir Expr<'hir>>,
1182 /// Can be `ForLoopDesugar` if the `let` statement is part of a `for` loop
1183 /// desugaring. Otherwise will be `Normal`.
1184 pub source: LocalSource,
1187 /// Represents a single arm of a `match` expression, e.g.
1188 /// `<pat> (if <guard>) => <body>`.
1189 #[derive(Debug, HashStable_Generic)]
1190 pub struct Arm<'hir> {
1191 #[stable_hasher(ignore)]
1194 pub attrs: &'hir [Attribute],
1195 /// If this pattern and the optional guard matches, then `body` is evaluated.
1196 pub pat: &'hir Pat<'hir>,
1197 /// Optional guard clause.
1198 pub guard: Option<Guard<'hir>>,
1199 /// The expression the arm evaluates to if this arm matches.
1200 pub body: &'hir Expr<'hir>,
1203 #[derive(Debug, HashStable_Generic)]
1204 pub enum Guard<'hir> {
1205 If(&'hir Expr<'hir>),
1206 IfLet(&'hir Pat<'hir>, &'hir Expr<'hir>),
1209 #[derive(Debug, HashStable_Generic)]
1210 pub struct Field<'hir> {
1211 #[stable_hasher(ignore)]
1214 pub expr: &'hir Expr<'hir>,
1216 pub is_shorthand: bool,
1219 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
1220 pub enum BlockCheckMode {
1222 UnsafeBlock(UnsafeSource),
1223 PushUnsafeBlock(UnsafeSource),
1224 PopUnsafeBlock(UnsafeSource),
1227 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
1228 pub enum UnsafeSource {
1233 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Encodable, Hash, Debug)]
1238 /// The body of a function, closure, or constant value. In the case of
1239 /// a function, the body contains not only the function body itself
1240 /// (which is an expression), but also the argument patterns, since
1241 /// those are something that the caller doesn't really care about.
1246 /// fn foo((x, y): (u32, u32)) -> u32 {
1251 /// Here, the `Body` associated with `foo()` would contain:
1253 /// - an `params` array containing the `(x, y)` pattern
1254 /// - a `value` containing the `x + y` expression (maybe wrapped in a block)
1255 /// - `generator_kind` would be `None`
1257 /// All bodies have an **owner**, which can be accessed via the HIR
1258 /// map using `body_owner_def_id()`.
1260 pub struct Body<'hir> {
1261 pub params: &'hir [Param<'hir>],
1262 pub value: Expr<'hir>,
1263 pub generator_kind: Option<GeneratorKind>,
1267 pub fn id(&self) -> BodyId {
1268 BodyId { hir_id: self.value.hir_id }
1271 pub fn generator_kind(&self) -> Option<GeneratorKind> {
1276 /// The type of source expression that caused this generator to be created.
1277 #[derive(Clone, PartialEq, Eq, HashStable_Generic, Encodable, Decodable, Debug, Copy)]
1278 pub enum GeneratorKind {
1279 /// An explicit `async` block or the body of an async function.
1280 Async(AsyncGeneratorKind),
1282 /// A generator literal created via a `yield` inside a closure.
1286 impl fmt::Display for GeneratorKind {
1287 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1289 GeneratorKind::Async(k) => fmt::Display::fmt(k, f),
1290 GeneratorKind::Gen => f.write_str("generator"),
1295 /// In the case of a generator created as part of an async construct,
1296 /// which kind of async construct caused it to be created?
1298 /// This helps error messages but is also used to drive coercions in
1299 /// type-checking (see #60424).
1300 #[derive(Clone, PartialEq, Eq, HashStable_Generic, Encodable, Decodable, Debug, Copy)]
1301 pub enum AsyncGeneratorKind {
1302 /// An explicit `async` block written by the user.
1305 /// An explicit `async` block written by the user.
1308 /// The `async` block generated as the body of an async function.
1312 impl fmt::Display for AsyncGeneratorKind {
1313 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1314 f.write_str(match self {
1315 AsyncGeneratorKind::Block => "`async` block",
1316 AsyncGeneratorKind::Closure => "`async` closure body",
1317 AsyncGeneratorKind::Fn => "`async fn` body",
1322 #[derive(Copy, Clone, Debug)]
1323 pub enum BodyOwnerKind {
1324 /// Functions and methods.
1330 /// Constants and associated constants.
1333 /// Initializer of a `static` item.
1337 impl BodyOwnerKind {
1338 pub fn is_fn_or_closure(self) -> bool {
1340 BodyOwnerKind::Fn | BodyOwnerKind::Closure => true,
1341 BodyOwnerKind::Const | BodyOwnerKind::Static(_) => false,
1346 /// The kind of an item that requires const-checking.
1347 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
1348 pub enum ConstContext {
1352 /// A `static` or `static mut`.
1355 /// A `const`, associated `const`, or other const context.
1357 /// Other contexts include:
1358 /// - Array length expressions
1359 /// - Enum discriminants
1360 /// - Const generics
1362 /// For the most part, other contexts are treated just like a regular `const`, so they are
1363 /// lumped into the same category.
1368 /// A description of this const context that can appear between backticks in an error message.
1370 /// E.g. `const` or `static mut`.
1371 pub fn keyword_name(self) -> &'static str {
1373 Self::Const => "const",
1374 Self::Static(Mutability::Not) => "static",
1375 Self::Static(Mutability::Mut) => "static mut",
1376 Self::ConstFn => "const fn",
1381 /// A colloquial, trivially pluralizable description of this const context for use in error
1383 impl fmt::Display for ConstContext {
1384 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1386 Self::Const => write!(f, "constant"),
1387 Self::Static(_) => write!(f, "static"),
1388 Self::ConstFn => write!(f, "constant function"),
1394 pub type Lit = Spanned<LitKind>;
1396 /// A constant (expression) that's not an item or associated item,
1397 /// but needs its own `DefId` for type-checking, const-eval, etc.
1398 /// These are usually found nested inside types (e.g., array lengths)
1399 /// or expressions (e.g., repeat counts), and also used to define
1400 /// explicit discriminant values for enum variants.
1401 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Debug, HashStable_Generic)]
1402 pub struct AnonConst {
1409 pub struct Expr<'hir> {
1411 pub kind: ExprKind<'hir>,
1416 // `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
1417 #[cfg(target_arch = "x86_64")]
1418 rustc_data_structures::static_assert_size!(Expr<'static>, 72);
1421 pub fn precedence(&self) -> ExprPrecedence {
1423 ExprKind::Box(_) => ExprPrecedence::Box,
1424 ExprKind::ConstBlock(_) => ExprPrecedence::ConstBlock,
1425 ExprKind::Array(_) => ExprPrecedence::Array,
1426 ExprKind::Call(..) => ExprPrecedence::Call,
1427 ExprKind::MethodCall(..) => ExprPrecedence::MethodCall,
1428 ExprKind::Tup(_) => ExprPrecedence::Tup,
1429 ExprKind::Binary(op, ..) => ExprPrecedence::Binary(op.node.into()),
1430 ExprKind::Unary(..) => ExprPrecedence::Unary,
1431 ExprKind::Lit(_) => ExprPrecedence::Lit,
1432 ExprKind::Type(..) | ExprKind::Cast(..) => ExprPrecedence::Cast,
1433 ExprKind::DropTemps(ref expr, ..) => expr.precedence(),
1434 ExprKind::If(..) => ExprPrecedence::If,
1435 ExprKind::Loop(..) => ExprPrecedence::Loop,
1436 ExprKind::Match(..) => ExprPrecedence::Match,
1437 ExprKind::Closure(..) => ExprPrecedence::Closure,
1438 ExprKind::Block(..) => ExprPrecedence::Block,
1439 ExprKind::Assign(..) => ExprPrecedence::Assign,
1440 ExprKind::AssignOp(..) => ExprPrecedence::AssignOp,
1441 ExprKind::Field(..) => ExprPrecedence::Field,
1442 ExprKind::Index(..) => ExprPrecedence::Index,
1443 ExprKind::Path(..) => ExprPrecedence::Path,
1444 ExprKind::AddrOf(..) => ExprPrecedence::AddrOf,
1445 ExprKind::Break(..) => ExprPrecedence::Break,
1446 ExprKind::Continue(..) => ExprPrecedence::Continue,
1447 ExprKind::Ret(..) => ExprPrecedence::Ret,
1448 ExprKind::InlineAsm(..) => ExprPrecedence::InlineAsm,
1449 ExprKind::LlvmInlineAsm(..) => ExprPrecedence::InlineAsm,
1450 ExprKind::Struct(..) => ExprPrecedence::Struct,
1451 ExprKind::Repeat(..) => ExprPrecedence::Repeat,
1452 ExprKind::Yield(..) => ExprPrecedence::Yield,
1453 ExprKind::Err => ExprPrecedence::Err,
1457 // Whether this looks like a place expr, without checking for deref
1459 // This will return `true` in some potentially surprising cases such as
1460 // `CONSTANT.field`.
1461 pub fn is_syntactic_place_expr(&self) -> bool {
1462 self.is_place_expr(|_| true)
1465 /// Whether this is a place expression.
1467 /// `allow_projections_from` should return `true` if indexing a field or index expression based
1468 /// on the given expression should be considered a place expression.
1469 pub fn is_place_expr(&self, mut allow_projections_from: impl FnMut(&Self) -> bool) -> bool {
1471 ExprKind::Path(QPath::Resolved(_, ref path)) => {
1472 matches!(path.res, Res::Local(..) | Res::Def(DefKind::Static, _) | Res::Err)
1475 // Type ascription inherits its place expression kind from its
1477 // https://github.com/rust-lang/rfcs/blob/master/text/0803-type-ascription.md#type-ascription-and-temporaries
1478 ExprKind::Type(ref e, _) => e.is_place_expr(allow_projections_from),
1480 ExprKind::Unary(UnOp::Deref, _) => true,
1482 ExprKind::Field(ref base, _) | ExprKind::Index(ref base, _) => {
1483 allow_projections_from(base) || base.is_place_expr(allow_projections_from)
1486 // Lang item paths cannot currently be local variables or statics.
1487 ExprKind::Path(QPath::LangItem(..)) => false,
1489 // Partially qualified paths in expressions can only legally
1490 // refer to associated items which are always rvalues.
1491 ExprKind::Path(QPath::TypeRelative(..))
1492 | ExprKind::Call(..)
1493 | ExprKind::MethodCall(..)
1494 | ExprKind::Struct(..)
1497 | ExprKind::Match(..)
1498 | ExprKind::Closure(..)
1499 | ExprKind::Block(..)
1500 | ExprKind::Repeat(..)
1501 | ExprKind::Array(..)
1502 | ExprKind::Break(..)
1503 | ExprKind::Continue(..)
1505 | ExprKind::Loop(..)
1506 | ExprKind::Assign(..)
1507 | ExprKind::InlineAsm(..)
1508 | ExprKind::LlvmInlineAsm(..)
1509 | ExprKind::AssignOp(..)
1511 | ExprKind::ConstBlock(..)
1512 | ExprKind::Unary(..)
1514 | ExprKind::AddrOf(..)
1515 | ExprKind::Binary(..)
1516 | ExprKind::Yield(..)
1517 | ExprKind::Cast(..)
1518 | ExprKind::DropTemps(..)
1519 | ExprKind::Err => false,
1523 /// If `Self.kind` is `ExprKind::DropTemps(expr)`, drill down until we get a non-`DropTemps`
1524 /// `Expr`. This is used in suggestions to ignore this `ExprKind` as it is semantically
1525 /// silent, only signaling the ownership system. By doing this, suggestions that check the
1526 /// `ExprKind` of any given `Expr` for presentation don't have to care about `DropTemps`
1527 /// beyond remembering to call this function before doing analysis on it.
1528 pub fn peel_drop_temps(&self) -> &Self {
1529 let mut expr = self;
1530 while let ExprKind::DropTemps(inner) = &expr.kind {
1537 /// Checks if the specified expression is a built-in range literal.
1538 /// (See: `LoweringContext::lower_expr()`).
1539 pub fn is_range_literal(expr: &Expr<'_>) -> bool {
1541 // All built-in range literals but `..=` and `..` desugar to `Struct`s.
1542 ExprKind::Struct(ref qpath, _, _) => matches!(
1547 | LangItem::RangeFrom
1548 | LangItem::RangeFull
1549 | LangItem::RangeToInclusive,
1554 // `..=` desugars into `::std::ops::RangeInclusive::new(...)`.
1555 ExprKind::Call(ref func, _) => {
1556 matches!(func.kind, ExprKind::Path(QPath::LangItem(LangItem::RangeInclusiveNew, _)))
1563 #[derive(Debug, HashStable_Generic)]
1564 pub enum ExprKind<'hir> {
1565 /// A `box x` expression.
1566 Box(&'hir Expr<'hir>),
1567 /// Allow anonymous constants from an inline `const` block
1568 ConstBlock(AnonConst),
1569 /// An array (e.g., `[a, b, c, d]`).
1570 Array(&'hir [Expr<'hir>]),
1571 /// A function call.
1573 /// The first field resolves to the function itself (usually an `ExprKind::Path`),
1574 /// and the second field is the list of arguments.
1575 /// This also represents calling the constructor of
1576 /// tuple-like ADTs such as tuple structs and enum variants.
1577 Call(&'hir Expr<'hir>, &'hir [Expr<'hir>]),
1578 /// A method call (e.g., `x.foo::<'static, Bar, Baz>(a, b, c, d)`).
1580 /// The `PathSegment`/`Span` represent the method name and its generic arguments
1581 /// (within the angle brackets).
1582 /// The first element of the vector of `Expr`s is the expression that evaluates
1583 /// to the object on which the method is being called on (the receiver),
1584 /// and the remaining elements are the rest of the arguments.
1585 /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
1586 /// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, [x, a, b, c, d])`.
1587 /// The final `Span` represents the span of the function and arguments
1588 /// (e.g. `foo::<Bar, Baz>(a, b, c, d)` in `x.foo::<Bar, Baz>(a, b, c, d)`
1590 /// To resolve the called method to a `DefId`, call [`type_dependent_def_id`] with
1591 /// the `hir_id` of the `MethodCall` node itself.
1593 /// [`type_dependent_def_id`]: ../ty/struct.TypeckResults.html#method.type_dependent_def_id
1594 MethodCall(&'hir PathSegment<'hir>, Span, &'hir [Expr<'hir>], Span),
1595 /// A tuple (e.g., `(a, b, c, d)`).
1596 Tup(&'hir [Expr<'hir>]),
1597 /// A binary operation (e.g., `a + b`, `a * b`).
1598 Binary(BinOp, &'hir Expr<'hir>, &'hir Expr<'hir>),
1599 /// A unary operation (e.g., `!x`, `*x`).
1600 Unary(UnOp, &'hir Expr<'hir>),
1601 /// A literal (e.g., `1`, `"foo"`).
1603 /// A cast (e.g., `foo as f64`).
1604 Cast(&'hir Expr<'hir>, &'hir Ty<'hir>),
1605 /// A type reference (e.g., `Foo`).
1606 Type(&'hir Expr<'hir>, &'hir Ty<'hir>),
1607 /// Wraps the expression in a terminating scope.
1608 /// This makes it semantically equivalent to `{ let _t = expr; _t }`.
1610 /// This construct only exists to tweak the drop order in HIR lowering.
1611 /// An example of that is the desugaring of `for` loops.
1612 DropTemps(&'hir Expr<'hir>),
1613 /// An `if` block, with an optional else block.
1615 /// I.e., `if <expr> { <expr> } else { <expr> }`.
1616 If(&'hir Expr<'hir>, &'hir Expr<'hir>, Option<&'hir Expr<'hir>>),
1617 /// A conditionless loop (can be exited with `break`, `continue`, or `return`).
1619 /// I.e., `'label: loop { <block> }`.
1621 /// The `Span` is the loop header (`for x in y`/`while let pat = expr`).
1622 Loop(&'hir Block<'hir>, Option<Label>, LoopSource, Span),
1623 /// A `match` block, with a source that indicates whether or not it is
1624 /// the result of a desugaring, and if so, which kind.
1625 Match(&'hir Expr<'hir>, &'hir [Arm<'hir>], MatchSource),
1626 /// A closure (e.g., `move |a, b, c| {a + b + c}`).
1628 /// The `Span` is the argument block `|...|`.
1630 /// This may also be a generator literal or an `async block` as indicated by the
1631 /// `Option<Movability>`.
1632 Closure(CaptureBy, &'hir FnDecl<'hir>, BodyId, Span, Option<Movability>),
1633 /// A block (e.g., `'label: { ... }`).
1634 Block(&'hir Block<'hir>, Option<Label>),
1636 /// An assignment (e.g., `a = foo()`).
1637 Assign(&'hir Expr<'hir>, &'hir Expr<'hir>, Span),
1638 /// An assignment with an operator.
1641 AssignOp(BinOp, &'hir Expr<'hir>, &'hir Expr<'hir>),
1642 /// Access of a named (e.g., `obj.foo`) or unnamed (e.g., `obj.0`) struct or tuple field.
1643 Field(&'hir Expr<'hir>, Ident),
1644 /// An indexing operation (`foo[2]`).
1645 Index(&'hir Expr<'hir>, &'hir Expr<'hir>),
1647 /// Path to a definition, possibly containing lifetime or type parameters.
1650 /// A referencing operation (i.e., `&a` or `&mut a`).
1651 AddrOf(BorrowKind, Mutability, &'hir Expr<'hir>),
1652 /// A `break`, with an optional label to break.
1653 Break(Destination, Option<&'hir Expr<'hir>>),
1654 /// A `continue`, with an optional label.
1655 Continue(Destination),
1656 /// A `return`, with an optional value to be returned.
1657 Ret(Option<&'hir Expr<'hir>>),
1659 /// Inline assembly (from `asm!`), with its outputs and inputs.
1660 InlineAsm(&'hir InlineAsm<'hir>),
1661 /// Inline assembly (from `llvm_asm!`), with its outputs and inputs.
1662 LlvmInlineAsm(&'hir LlvmInlineAsm<'hir>),
1664 /// A struct or struct-like variant literal expression.
1666 /// E.g., `Foo {x: 1, y: 2}`, or `Foo {x: 1, .. base}`,
1667 /// where `base` is the `Option<Expr>`.
1668 Struct(&'hir QPath<'hir>, &'hir [Field<'hir>], Option<&'hir Expr<'hir>>),
1670 /// An array literal constructed from one repeated element.
1672 /// E.g., `[1; 5]`. The first expression is the element
1673 /// to be repeated; the second is the number of times to repeat it.
1674 Repeat(&'hir Expr<'hir>, AnonConst),
1676 /// A suspension point for generators (i.e., `yield <expr>`).
1677 Yield(&'hir Expr<'hir>, YieldSource),
1679 /// A placeholder for an expression that wasn't syntactically well formed in some way.
1683 /// Represents an optionally `Self`-qualified value/type path or associated extension.
1685 /// To resolve the path to a `DefId`, call [`qpath_res`].
1687 /// [`qpath_res`]: ../rustc_middle/ty/struct.TypeckResults.html#method.qpath_res
1688 #[derive(Debug, HashStable_Generic)]
1689 pub enum QPath<'hir> {
1690 /// Path to a definition, optionally "fully-qualified" with a `Self`
1691 /// type, if the path points to an associated item in a trait.
1693 /// E.g., an unqualified path like `Clone::clone` has `None` for `Self`,
1694 /// while `<Vec<T> as Clone>::clone` has `Some(Vec<T>)` for `Self`,
1695 /// even though they both have the same two-segment `Clone::clone` `Path`.
1696 Resolved(Option<&'hir Ty<'hir>>, &'hir Path<'hir>),
1698 /// Type-related paths (e.g., `<T>::default` or `<T>::Output`).
1699 /// Will be resolved by type-checking to an associated item.
1701 /// UFCS source paths can desugar into this, with `Vec::new` turning into
1702 /// `<Vec>::new`, and `T::X::Y::method` into `<<<T>::X>::Y>::method`,
1703 /// the `X` and `Y` nodes each being a `TyKind::Path(QPath::TypeRelative(..))`.
1704 TypeRelative(&'hir Ty<'hir>, &'hir PathSegment<'hir>),
1706 /// Reference to a `#[lang = "foo"]` item.
1707 LangItem(LangItem, Span),
1710 impl<'hir> QPath<'hir> {
1711 /// Returns the span of this `QPath`.
1712 pub fn span(&self) -> Span {
1714 QPath::Resolved(_, path) => path.span,
1715 QPath::TypeRelative(_, ps) => ps.ident.span,
1716 QPath::LangItem(_, span) => span,
1720 /// Returns the span of the qself of this `QPath`. For example, `()` in
1721 /// `<() as Trait>::method`.
1722 pub fn qself_span(&self) -> Span {
1724 QPath::Resolved(_, path) => path.span,
1725 QPath::TypeRelative(qself, _) => qself.span,
1726 QPath::LangItem(_, span) => span,
1730 /// Returns the span of the last segment of this `QPath`. For example, `method` in
1731 /// `<() as Trait>::method`.
1732 pub fn last_segment_span(&self) -> Span {
1734 QPath::Resolved(_, path) => path.segments.last().unwrap().ident.span,
1735 QPath::TypeRelative(_, segment) => segment.ident.span,
1736 QPath::LangItem(_, span) => span,
1741 /// Hints at the original code for a let statement.
1742 #[derive(Copy, Clone, Encodable, Debug, HashStable_Generic)]
1743 pub enum LocalSource {
1744 /// A `match _ { .. }`.
1746 /// A desugared `for _ in _ { .. }` loop.
1748 /// When lowering async functions, we create locals within the `async move` so that
1749 /// all parameters are dropped after the future is polled.
1751 /// ```ignore (pseudo-Rust)
1752 /// async fn foo(<pattern> @ x: Type) {
1754 /// let <pattern> = x;
1759 /// A desugared `<expr>.await`.
1761 /// A desugared `expr = expr`, where the LHS is a tuple, struct or array.
1762 /// The span is that of the `=` sign.
1763 AssignDesugar(Span),
1766 /// Hints at the original code for a `match _ { .. }`.
1767 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Hash, Debug)]
1768 #[derive(HashStable_Generic)]
1769 pub enum MatchSource {
1770 /// A `match _ { .. }`.
1772 /// An `if let _ = _ { .. }` (optionally with `else { .. }`).
1773 IfLetDesugar { contains_else_clause: bool },
1774 /// An `if let _ = _ => { .. }` match guard.
1776 /// A `while _ { .. }` (which was desugared to a `loop { match _ { .. } }`).
1778 /// A `while let _ = _ { .. }` (which was desugared to a
1779 /// `loop { match _ { .. } }`).
1781 /// A desugared `for _ in _ { .. }` loop.
1783 /// A desugared `?` operator.
1785 /// A desugared `<expr>.await`.
1790 pub fn name(self) -> &'static str {
1794 IfLetDesugar { .. } | IfLetGuardDesugar => "if",
1795 WhileDesugar | WhileLetDesugar => "while",
1796 ForLoopDesugar => "for",
1798 AwaitDesugar => ".await",
1803 /// The loop type that yielded an `ExprKind::Loop`.
1804 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
1805 pub enum LoopSource {
1806 /// A `loop { .. }` loop.
1808 /// A `while _ { .. }` loop.
1810 /// A `while let _ = _ { .. }` loop.
1812 /// A `for _ in _ { .. }` loop.
1817 pub fn name(self) -> &'static str {
1819 LoopSource::Loop => "loop",
1820 LoopSource::While | LoopSource::WhileLet => "while",
1821 LoopSource::ForLoop => "for",
1826 #[derive(Copy, Clone, Encodable, Debug, HashStable_Generic)]
1827 pub enum LoopIdError {
1829 UnlabeledCfInWhileCondition,
1833 impl fmt::Display for LoopIdError {
1834 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1835 f.write_str(match self {
1836 LoopIdError::OutsideLoopScope => "not inside loop scope",
1837 LoopIdError::UnlabeledCfInWhileCondition => {
1838 "unlabeled control flow (break or continue) in while condition"
1840 LoopIdError::UnresolvedLabel => "label not found",
1845 #[derive(Copy, Clone, Encodable, Debug, HashStable_Generic)]
1846 pub struct Destination {
1847 // This is `Some(_)` iff there is an explicit user-specified `label
1848 pub label: Option<Label>,
1850 // These errors are caught and then reported during the diagnostics pass in
1851 // librustc_passes/loops.rs
1852 pub target_id: Result<HirId, LoopIdError>,
1855 /// The yield kind that caused an `ExprKind::Yield`.
1856 #[derive(Copy, Clone, PartialEq, Eq, Debug, Encodable, Decodable, HashStable_Generic)]
1857 pub enum YieldSource {
1858 /// An `<expr>.await`.
1859 Await { expr: Option<HirId> },
1860 /// A plain `yield`.
1865 pub fn is_await(&self) -> bool {
1867 YieldSource::Await { .. } => true,
1868 YieldSource::Yield => false,
1873 impl fmt::Display for YieldSource {
1874 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1875 f.write_str(match self {
1876 YieldSource::Await { .. } => "`await`",
1877 YieldSource::Yield => "`yield`",
1882 impl From<GeneratorKind> for YieldSource {
1883 fn from(kind: GeneratorKind) -> Self {
1885 // Guess based on the kind of the current generator.
1886 GeneratorKind::Gen => Self::Yield,
1887 GeneratorKind::Async(_) => Self::Await { expr: None },
1892 // N.B., if you change this, you'll probably want to change the corresponding
1893 // type structure in middle/ty.rs as well.
1894 #[derive(Debug, HashStable_Generic)]
1895 pub struct MutTy<'hir> {
1896 pub ty: &'hir Ty<'hir>,
1897 pub mutbl: Mutability,
1900 /// Represents a function's signature in a trait declaration,
1901 /// trait implementation, or a free function.
1902 #[derive(Debug, HashStable_Generic)]
1903 pub struct FnSig<'hir> {
1904 pub header: FnHeader,
1905 pub decl: &'hir FnDecl<'hir>,
1909 // The bodies for items are stored "out of line", in a separate
1910 // hashmap in the `Crate`. Here we just record the hir-id of the item
1911 // so it can fetched later.
1912 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Encodable, Debug)]
1913 pub struct TraitItemId {
1917 /// Represents an item declaration within a trait declaration,
1918 /// possibly including a default implementation. A trait item is
1919 /// either required (meaning it doesn't have an implementation, just a
1920 /// signature) or provided (meaning it has a default implementation).
1922 pub struct TraitItem<'hir> {
1925 pub attrs: &'hir [Attribute],
1926 pub generics: Generics<'hir>,
1927 pub kind: TraitItemKind<'hir>,
1931 /// Represents a trait method's body (or just argument names).
1932 #[derive(Encodable, Debug, HashStable_Generic)]
1933 pub enum TraitFn<'hir> {
1934 /// No default body in the trait, just a signature.
1935 Required(&'hir [Ident]),
1937 /// Both signature and body are provided in the trait.
1941 /// Represents a trait method or associated constant or type
1942 #[derive(Debug, HashStable_Generic)]
1943 pub enum TraitItemKind<'hir> {
1944 /// An associated constant with an optional value (otherwise `impl`s must contain a value).
1945 Const(&'hir Ty<'hir>, Option<BodyId>),
1946 /// An associated function with an optional body.
1947 Fn(FnSig<'hir>, TraitFn<'hir>),
1948 /// An associated type with (possibly empty) bounds and optional concrete
1950 Type(GenericBounds<'hir>, Option<&'hir Ty<'hir>>),
1953 // The bodies for items are stored "out of line", in a separate
1954 // hashmap in the `Crate`. Here we just record the hir-id of the item
1955 // so it can fetched later.
1956 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Encodable, Debug)]
1957 pub struct ImplItemId {
1961 /// Represents anything within an `impl` block.
1963 pub struct ImplItem<'hir> {
1966 pub vis: Visibility<'hir>,
1967 pub defaultness: Defaultness,
1968 pub attrs: &'hir [Attribute],
1969 pub generics: Generics<'hir>,
1970 pub kind: ImplItemKind<'hir>,
1974 /// Represents various kinds of content within an `impl`.
1975 #[derive(Debug, HashStable_Generic)]
1976 pub enum ImplItemKind<'hir> {
1977 /// An associated constant of the given type, set to the constant result
1978 /// of the expression.
1979 Const(&'hir Ty<'hir>, BodyId),
1980 /// An associated function implementation with the given signature and body.
1981 Fn(FnSig<'hir>, BodyId),
1982 /// An associated type.
1983 TyAlias(&'hir Ty<'hir>),
1986 impl ImplItemKind<'_> {
1987 pub fn namespace(&self) -> Namespace {
1989 ImplItemKind::TyAlias(..) => Namespace::TypeNS,
1990 ImplItemKind::Const(..) | ImplItemKind::Fn(..) => Namespace::ValueNS,
1995 // The name of the associated type for `Fn` return types.
1996 pub const FN_OUTPUT_NAME: Symbol = sym::Output;
1998 /// Bind a type to an associated type (i.e., `A = Foo`).
2000 /// Bindings like `A: Debug` are represented as a special type `A =
2001 /// $::Debug` that is understood by the astconv code.
2003 /// FIXME(alexreg): why have a separate type for the binding case,
2004 /// wouldn't it be better to make the `ty` field an enum like the
2008 /// enum TypeBindingKind {
2013 #[derive(Debug, HashStable_Generic)]
2014 pub struct TypeBinding<'hir> {
2016 #[stable_hasher(project(name))]
2018 pub gen_args: &'hir GenericArgs<'hir>,
2019 pub kind: TypeBindingKind<'hir>,
2023 // Represents the two kinds of type bindings.
2024 #[derive(Debug, HashStable_Generic)]
2025 pub enum TypeBindingKind<'hir> {
2026 /// E.g., `Foo<Bar: Send>`.
2027 Constraint { bounds: &'hir [GenericBound<'hir>] },
2028 /// E.g., `Foo<Bar = ()>`.
2029 Equality { ty: &'hir Ty<'hir> },
2032 impl TypeBinding<'_> {
2033 pub fn ty(&self) -> &Ty<'_> {
2035 TypeBindingKind::Equality { ref ty } => ty,
2036 _ => panic!("expected equality type binding for parenthesized generic args"),
2042 pub struct Ty<'hir> {
2044 pub kind: TyKind<'hir>,
2048 /// Not represented directly in the AST; referred to by name through a `ty_path`.
2049 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
2050 #[derive(HashStable_Generic)]
2061 /// All of the primitive types
2062 pub const ALL: [Self; 17] = [
2063 // any changes here should also be reflected in `PrimTy::from_name`
2064 Self::Int(IntTy::I8),
2065 Self::Int(IntTy::I16),
2066 Self::Int(IntTy::I32),
2067 Self::Int(IntTy::I64),
2068 Self::Int(IntTy::I128),
2069 Self::Int(IntTy::Isize),
2070 Self::Uint(UintTy::U8),
2071 Self::Uint(UintTy::U16),
2072 Self::Uint(UintTy::U32),
2073 Self::Uint(UintTy::U64),
2074 Self::Uint(UintTy::U128),
2075 Self::Uint(UintTy::Usize),
2076 Self::Float(FloatTy::F32),
2077 Self::Float(FloatTy::F64),
2083 pub fn name_str(self) -> &'static str {
2085 PrimTy::Int(i) => i.name_str(),
2086 PrimTy::Uint(u) => u.name_str(),
2087 PrimTy::Float(f) => f.name_str(),
2088 PrimTy::Str => "str",
2089 PrimTy::Bool => "bool",
2090 PrimTy::Char => "char",
2094 pub fn name(self) -> Symbol {
2096 PrimTy::Int(i) => i.name(),
2097 PrimTy::Uint(u) => u.name(),
2098 PrimTy::Float(f) => f.name(),
2099 PrimTy::Str => sym::str,
2100 PrimTy::Bool => sym::bool,
2101 PrimTy::Char => sym::char,
2105 /// Returns the matching `PrimTy` for a `Symbol` such as "str" or "i32".
2106 /// Returns `None` if no matching type is found.
2107 pub fn from_name(name: Symbol) -> Option<Self> {
2108 let ty = match name {
2109 // any changes here should also be reflected in `PrimTy::ALL`
2110 sym::i8 => Self::Int(IntTy::I8),
2111 sym::i16 => Self::Int(IntTy::I16),
2112 sym::i32 => Self::Int(IntTy::I32),
2113 sym::i64 => Self::Int(IntTy::I64),
2114 sym::i128 => Self::Int(IntTy::I128),
2115 sym::isize => Self::Int(IntTy::Isize),
2116 sym::u8 => Self::Uint(UintTy::U8),
2117 sym::u16 => Self::Uint(UintTy::U16),
2118 sym::u32 => Self::Uint(UintTy::U32),
2119 sym::u64 => Self::Uint(UintTy::U64),
2120 sym::u128 => Self::Uint(UintTy::U128),
2121 sym::usize => Self::Uint(UintTy::Usize),
2122 sym::f32 => Self::Float(FloatTy::F32),
2123 sym::f64 => Self::Float(FloatTy::F64),
2124 sym::bool => Self::Bool,
2125 sym::char => Self::Char,
2126 sym::str => Self::Str,
2133 #[derive(Debug, HashStable_Generic)]
2134 pub struct BareFnTy<'hir> {
2135 pub unsafety: Unsafety,
2137 pub generic_params: &'hir [GenericParam<'hir>],
2138 pub decl: &'hir FnDecl<'hir>,
2139 pub param_names: &'hir [Ident],
2142 #[derive(Debug, HashStable_Generic)]
2143 pub struct OpaqueTy<'hir> {
2144 pub generics: Generics<'hir>,
2145 pub bounds: GenericBounds<'hir>,
2146 pub impl_trait_fn: Option<DefId>,
2147 pub origin: OpaqueTyOrigin,
2150 /// From whence the opaque type came.
2151 #[derive(Copy, Clone, Encodable, Decodable, Debug, HashStable_Generic)]
2152 pub enum OpaqueTyOrigin {
2157 /// `let _: impl Trait = ...`
2159 /// Impl trait in type aliases, consts, statics, bounds.
2163 /// The various kinds of types recognized by the compiler.
2164 #[derive(Debug, HashStable_Generic)]
2165 pub enum TyKind<'hir> {
2166 /// A variable length slice (i.e., `[T]`).
2167 Slice(&'hir Ty<'hir>),
2168 /// A fixed length array (i.e., `[T; n]`).
2169 Array(&'hir Ty<'hir>, AnonConst),
2170 /// A raw pointer (i.e., `*const T` or `*mut T`).
2172 /// A reference (i.e., `&'a T` or `&'a mut T`).
2173 Rptr(Lifetime, MutTy<'hir>),
2174 /// A bare function (e.g., `fn(usize) -> bool`).
2175 BareFn(&'hir BareFnTy<'hir>),
2176 /// The never type (`!`).
2178 /// A tuple (`(A, B, C, D, ...)`).
2179 Tup(&'hir [Ty<'hir>]),
2180 /// A path to a type definition (`module::module::...::Type`), or an
2181 /// associated type (e.g., `<Vec<T> as Trait>::Type` or `<T>::Target`).
2183 /// Type parameters may be stored in each `PathSegment`.
2185 /// A opaque type definition itself. This is currently only used for the
2186 /// `opaque type Foo: Trait` item that `impl Trait` in desugars to.
2188 /// The generic argument list contains the lifetimes (and in the future
2189 /// possibly parameters) that are actually bound on the `impl Trait`.
2190 OpaqueDef(ItemId, &'hir [GenericArg<'hir>]),
2191 /// A trait object type `Bound1 + Bound2 + Bound3`
2192 /// where `Bound` is a trait or a lifetime.
2193 TraitObject(&'hir [PolyTraitRef<'hir>], Lifetime),
2196 /// `TyKind::Infer` means the type should be inferred instead of it having been
2197 /// specified. This can appear anywhere in a type.
2199 /// Placeholder for a type that has failed to be defined.
2203 #[derive(Debug, HashStable_Generic)]
2204 pub enum InlineAsmOperand<'hir> {
2206 reg: InlineAsmRegOrRegClass,
2210 reg: InlineAsmRegOrRegClass,
2212 expr: Option<Expr<'hir>>,
2215 reg: InlineAsmRegOrRegClass,
2220 reg: InlineAsmRegOrRegClass,
2222 in_expr: Expr<'hir>,
2223 out_expr: Option<Expr<'hir>>,
2233 impl<'hir> InlineAsmOperand<'hir> {
2234 pub fn reg(&self) -> Option<InlineAsmRegOrRegClass> {
2236 Self::In { reg, .. }
2237 | Self::Out { reg, .. }
2238 | Self::InOut { reg, .. }
2239 | Self::SplitInOut { reg, .. } => Some(reg),
2240 Self::Const { .. } | Self::Sym { .. } => None,
2245 #[derive(Debug, HashStable_Generic)]
2246 pub struct InlineAsm<'hir> {
2247 pub template: &'hir [InlineAsmTemplatePiece],
2248 pub operands: &'hir [(InlineAsmOperand<'hir>, Span)],
2249 pub options: InlineAsmOptions,
2250 pub line_spans: &'hir [Span],
2253 #[derive(Copy, Clone, Encodable, Decodable, Debug, HashStable_Generic, PartialEq)]
2254 pub struct LlvmInlineAsmOutput {
2255 pub constraint: Symbol,
2257 pub is_indirect: bool,
2261 // NOTE(eddyb) This is used within MIR as well, so unlike the rest of the HIR,
2262 // it needs to be `Clone` and `Decodable` and use plain `Vec<T>` instead of
2263 // arena-allocated slice.
2264 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic, PartialEq)]
2265 pub struct LlvmInlineAsmInner {
2267 pub asm_str_style: StrStyle,
2268 pub outputs: Vec<LlvmInlineAsmOutput>,
2269 pub inputs: Vec<Symbol>,
2270 pub clobbers: Vec<Symbol>,
2272 pub alignstack: bool,
2273 pub dialect: LlvmAsmDialect,
2276 #[derive(Debug, HashStable_Generic)]
2277 pub struct LlvmInlineAsm<'hir> {
2278 pub inner: LlvmInlineAsmInner,
2279 pub outputs_exprs: &'hir [Expr<'hir>],
2280 pub inputs_exprs: &'hir [Expr<'hir>],
2283 /// Represents a parameter in a function header.
2284 #[derive(Debug, HashStable_Generic)]
2285 pub struct Param<'hir> {
2286 pub attrs: &'hir [Attribute],
2288 pub pat: &'hir Pat<'hir>,
2293 /// Represents the header (not the body) of a function declaration.
2294 #[derive(Debug, HashStable_Generic)]
2295 pub struct FnDecl<'hir> {
2296 /// The types of the function's parameters.
2298 /// Additional argument data is stored in the function's [body](Body::params).
2299 pub inputs: &'hir [Ty<'hir>],
2300 pub output: FnRetTy<'hir>,
2301 pub c_variadic: bool,
2302 /// Does the function have an implicit self?
2303 pub implicit_self: ImplicitSelfKind,
2306 /// Represents what type of implicit self a function has, if any.
2307 #[derive(Copy, Clone, Encodable, Decodable, Debug, HashStable_Generic)]
2308 pub enum ImplicitSelfKind {
2309 /// Represents a `fn x(self);`.
2311 /// Represents a `fn x(mut self);`.
2313 /// Represents a `fn x(&self);`.
2315 /// Represents a `fn x(&mut self);`.
2317 /// Represents when a function does not have a self argument or
2318 /// when a function has a `self: X` argument.
2322 impl ImplicitSelfKind {
2323 /// Does this represent an implicit self?
2324 pub fn has_implicit_self(&self) -> bool {
2325 !matches!(*self, ImplicitSelfKind::None)
2329 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Encodable, Decodable, Debug)]
2330 #[derive(HashStable_Generic)]
2336 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, Encodable, Decodable, HashStable_Generic)]
2337 pub enum Defaultness {
2338 Default { has_value: bool },
2343 pub fn has_value(&self) -> bool {
2345 Defaultness::Default { has_value } => has_value,
2346 Defaultness::Final => true,
2350 pub fn is_final(&self) -> bool {
2351 *self == Defaultness::Final
2354 pub fn is_default(&self) -> bool {
2355 matches!(*self, Defaultness::Default { .. })
2359 #[derive(Debug, HashStable_Generic)]
2360 pub enum FnRetTy<'hir> {
2361 /// Return type is not specified.
2363 /// Functions default to `()` and
2364 /// closures default to inference. Span points to where return
2365 /// type would be inserted.
2366 DefaultReturn(Span),
2367 /// Everything else.
2368 Return(&'hir Ty<'hir>),
2372 pub fn span(&self) -> Span {
2374 Self::DefaultReturn(span) => span,
2375 Self::Return(ref ty) => ty.span,
2380 #[derive(Encodable, Debug)]
2381 pub struct Mod<'hir> {
2382 /// A span from the first token past `{` to the last token until `}`.
2383 /// For `mod foo;`, the inner span ranges from the first token
2384 /// to the last token in the external file.
2386 pub item_ids: &'hir [ItemId],
2389 #[derive(Encodable, Debug, HashStable_Generic)]
2390 pub struct GlobalAsm {
2394 #[derive(Debug, HashStable_Generic)]
2395 pub struct EnumDef<'hir> {
2396 pub variants: &'hir [Variant<'hir>],
2399 #[derive(Debug, HashStable_Generic)]
2400 pub struct Variant<'hir> {
2401 /// Name of the variant.
2402 #[stable_hasher(project(name))]
2404 /// Attributes of the variant.
2405 pub attrs: &'hir [Attribute],
2406 /// Id of the variant (not the constructor, see `VariantData::ctor_hir_id()`).
2408 /// Fields and constructor id of the variant.
2409 pub data: VariantData<'hir>,
2410 /// Explicit discriminant (e.g., `Foo = 1`).
2411 pub disr_expr: Option<AnonConst>,
2416 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
2418 /// One import, e.g., `use foo::bar` or `use foo::bar as baz`.
2419 /// Also produced for each element of a list `use`, e.g.
2420 /// `use foo::{a, b}` lowers to `use foo::a; use foo::b;`.
2423 /// Glob import, e.g., `use foo::*`.
2426 /// Degenerate list import, e.g., `use foo::{a, b}` produces
2427 /// an additional `use foo::{}` for performing checks such as
2428 /// unstable feature gating. May be removed in the future.
2432 /// References to traits in impls.
2434 /// `resolve` maps each `TraitRef`'s `ref_id` to its defining trait; that's all
2435 /// that the `ref_id` is for. Note that `ref_id`'s value is not the `HirId` of the
2436 /// trait being referred to but just a unique `HirId` that serves as a key
2437 /// within the resolution map.
2438 #[derive(Debug, HashStable_Generic)]
2439 pub struct TraitRef<'hir> {
2440 pub path: &'hir Path<'hir>,
2441 // Don't hash the `ref_id`. It is tracked via the thing it is used to access.
2442 #[stable_hasher(ignore)]
2443 pub hir_ref_id: HirId,
2447 /// Gets the `DefId` of the referenced trait. It _must_ actually be a trait or trait alias.
2448 pub fn trait_def_id(&self) -> Option<DefId> {
2449 match self.path.res {
2450 Res::Def(DefKind::Trait | DefKind::TraitAlias, did) => Some(did),
2452 _ => unreachable!(),
2457 #[derive(Debug, HashStable_Generic)]
2458 pub struct PolyTraitRef<'hir> {
2459 /// The `'a` in `for<'a> Foo<&'a T>`.
2460 pub bound_generic_params: &'hir [GenericParam<'hir>],
2462 /// The `Foo<&'a T>` in `for<'a> Foo<&'a T>`.
2463 pub trait_ref: TraitRef<'hir>,
2468 pub type Visibility<'hir> = Spanned<VisibilityKind<'hir>>;
2471 pub enum VisibilityKind<'hir> {
2474 Restricted { path: &'hir Path<'hir>, hir_id: HirId },
2478 impl VisibilityKind<'_> {
2479 pub fn is_pub(&self) -> bool {
2480 matches!(*self, VisibilityKind::Public)
2483 pub fn is_pub_restricted(&self) -> bool {
2485 VisibilityKind::Public | VisibilityKind::Inherited => false,
2486 VisibilityKind::Crate(..) | VisibilityKind::Restricted { .. } => true,
2491 #[derive(Debug, HashStable_Generic)]
2492 pub struct StructField<'hir> {
2494 #[stable_hasher(project(name))]
2496 pub vis: Visibility<'hir>,
2498 pub ty: &'hir Ty<'hir>,
2499 pub attrs: &'hir [Attribute],
2502 impl StructField<'_> {
2503 // Still necessary in couple of places
2504 pub fn is_positional(&self) -> bool {
2505 let first = self.ident.as_str().as_bytes()[0];
2506 (b'0'..=b'9').contains(&first)
2510 /// Fields and constructor IDs of enum variants and structs.
2511 #[derive(Debug, HashStable_Generic)]
2512 pub enum VariantData<'hir> {
2513 /// A struct variant.
2515 /// E.g., `Bar { .. }` as in `enum Foo { Bar { .. } }`.
2516 Struct(&'hir [StructField<'hir>], /* recovered */ bool),
2517 /// A tuple variant.
2519 /// E.g., `Bar(..)` as in `enum Foo { Bar(..) }`.
2520 Tuple(&'hir [StructField<'hir>], HirId),
2523 /// E.g., `Bar = ..` as in `enum Foo { Bar = .. }`.
2527 impl VariantData<'hir> {
2528 /// Return the fields of this variant.
2529 pub fn fields(&self) -> &'hir [StructField<'hir>] {
2531 VariantData::Struct(ref fields, ..) | VariantData::Tuple(ref fields, ..) => fields,
2536 /// Return the `HirId` of this variant's constructor, if it has one.
2537 pub fn ctor_hir_id(&self) -> Option<HirId> {
2539 VariantData::Struct(_, _) => None,
2540 VariantData::Tuple(_, hir_id) | VariantData::Unit(hir_id) => Some(hir_id),
2545 // The bodies for items are stored "out of line", in a separate
2546 // hashmap in the `Crate`. Here we just record the hir-id of the item
2547 // so it can fetched later.
2548 #[derive(Copy, Clone, Encodable, Debug)]
2555 /// The name might be a dummy name in case of anonymous items
2557 pub struct Item<'hir> {
2560 pub attrs: &'hir [Attribute],
2561 pub kind: ItemKind<'hir>,
2562 pub vis: Visibility<'hir>,
2566 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
2567 #[derive(Encodable, Decodable, HashStable_Generic)]
2574 pub fn prefix_str(&self) -> &'static str {
2576 Self::Unsafe => "unsafe ",
2582 impl fmt::Display for Unsafety {
2583 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2584 f.write_str(match *self {
2585 Self::Unsafe => "unsafe",
2586 Self::Normal => "normal",
2591 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
2592 #[derive(Encodable, Decodable, HashStable_Generic)]
2593 pub enum Constness {
2598 #[derive(Copy, Clone, Encodable, Debug, HashStable_Generic)]
2599 pub struct FnHeader {
2600 pub unsafety: Unsafety,
2601 pub constness: Constness,
2602 pub asyncness: IsAsync,
2607 pub fn is_const(&self) -> bool {
2608 matches!(&self.constness, Constness::Const)
2612 #[derive(Debug, HashStable_Generic)]
2613 pub enum ItemKind<'hir> {
2614 /// An `extern crate` item, with optional *original* crate name if the crate was renamed.
2616 /// E.g., `extern crate foo` or `extern crate foo_bar as foo`.
2617 ExternCrate(Option<Symbol>),
2619 /// `use foo::bar::*;` or `use foo::bar::baz as quux;`
2623 /// `use foo::bar::baz;` (with `as baz` implicitly on the right).
2624 Use(&'hir Path<'hir>, UseKind),
2626 /// A `static` item.
2627 Static(&'hir Ty<'hir>, Mutability, BodyId),
2629 Const(&'hir Ty<'hir>, BodyId),
2630 /// A function declaration.
2631 Fn(FnSig<'hir>, Generics<'hir>, BodyId),
2634 /// An external module, e.g. `extern { .. }`.
2635 ForeignMod { abi: Abi, items: &'hir [ForeignItemRef<'hir>] },
2636 /// Module-level inline assembly (from `global_asm!`).
2637 GlobalAsm(&'hir GlobalAsm),
2638 /// A type alias, e.g., `type Foo = Bar<u8>`.
2639 TyAlias(&'hir Ty<'hir>, Generics<'hir>),
2640 /// An opaque `impl Trait` type alias, e.g., `type Foo = impl Bar;`.
2641 OpaqueTy(OpaqueTy<'hir>),
2642 /// An enum definition, e.g., `enum Foo<A, B> {C<A>, D<B>}`.
2643 Enum(EnumDef<'hir>, Generics<'hir>),
2644 /// A struct definition, e.g., `struct Foo<A> {x: A}`.
2645 Struct(VariantData<'hir>, Generics<'hir>),
2646 /// A union definition, e.g., `union Foo<A, B> {x: A, y: B}`.
2647 Union(VariantData<'hir>, Generics<'hir>),
2648 /// A trait definition.
2649 Trait(IsAuto, Unsafety, Generics<'hir>, GenericBounds<'hir>, &'hir [TraitItemRef]),
2651 TraitAlias(Generics<'hir>, GenericBounds<'hir>),
2653 /// An implementation, e.g., `impl<A> Trait for Foo { .. }`.
2657 #[derive(Debug, HashStable_Generic)]
2658 pub struct Impl<'hir> {
2659 pub unsafety: Unsafety,
2660 pub polarity: ImplPolarity,
2661 pub defaultness: Defaultness,
2662 // We do not put a `Span` in `Defaultness` because it breaks foreign crate metadata
2663 // decoding as `Span`s cannot be decoded when a `Session` is not available.
2664 pub defaultness_span: Option<Span>,
2665 pub constness: Constness,
2666 pub generics: Generics<'hir>,
2668 /// The trait being implemented, if any.
2669 pub of_trait: Option<TraitRef<'hir>>,
2671 pub self_ty: &'hir Ty<'hir>,
2672 pub items: &'hir [ImplItemRef<'hir>],
2676 pub fn generics(&self) -> Option<&Generics<'_>> {
2678 ItemKind::Fn(_, ref generics, _)
2679 | ItemKind::TyAlias(_, ref generics)
2680 | ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. })
2681 | ItemKind::Enum(_, ref generics)
2682 | ItemKind::Struct(_, ref generics)
2683 | ItemKind::Union(_, ref generics)
2684 | ItemKind::Trait(_, _, ref generics, _, _)
2685 | ItemKind::Impl(Impl { ref generics, .. }) => generics,
2691 /// A reference from an trait to one of its associated items. This
2692 /// contains the item's id, naturally, but also the item's name and
2693 /// some other high-level details (like whether it is an associated
2694 /// type or method, and whether it is public). This allows other
2695 /// passes to find the impl they want without loading the ID (which
2696 /// means fewer edges in the incremental compilation graph).
2697 #[derive(Encodable, Debug, HashStable_Generic)]
2698 pub struct TraitItemRef {
2699 pub id: TraitItemId,
2700 #[stable_hasher(project(name))]
2702 pub kind: AssocItemKind,
2704 pub defaultness: Defaultness,
2707 /// A reference from an impl to one of its associated items. This
2708 /// contains the item's ID, naturally, but also the item's name and
2709 /// some other high-level details (like whether it is an associated
2710 /// type or method, and whether it is public). This allows other
2711 /// passes to find the impl they want without loading the ID (which
2712 /// means fewer edges in the incremental compilation graph).
2713 #[derive(Debug, HashStable_Generic)]
2714 pub struct ImplItemRef<'hir> {
2716 #[stable_hasher(project(name))]
2718 pub kind: AssocItemKind,
2720 pub vis: Visibility<'hir>,
2721 pub defaultness: Defaultness,
2724 #[derive(Copy, Clone, PartialEq, Encodable, Debug, HashStable_Generic)]
2725 pub enum AssocItemKind {
2727 Fn { has_self: bool },
2731 // The bodies for items are stored "out of line", in a separate
2732 // hashmap in the `Crate`. Here we just record the hir-id of the item
2733 // so it can fetched later.
2734 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Encodable, Debug)]
2735 pub struct ForeignItemId {
2739 /// A reference from a foreign block to one of its items. This
2740 /// contains the item's ID, naturally, but also the item's name and
2741 /// some other high-level details (like whether it is an associated
2742 /// type or method, and whether it is public). This allows other
2743 /// passes to find the impl they want without loading the ID (which
2744 /// means fewer edges in the incremental compilation graph).
2745 #[derive(Debug, HashStable_Generic)]
2746 pub struct ForeignItemRef<'hir> {
2747 pub id: ForeignItemId,
2748 #[stable_hasher(project(name))]
2751 pub vis: Visibility<'hir>,
2754 #[derive(Debug, HashStable_Generic)]
2755 pub struct ForeignItem<'hir> {
2756 #[stable_hasher(project(name))]
2758 pub attrs: &'hir [Attribute],
2759 pub kind: ForeignItemKind<'hir>,
2762 pub vis: Visibility<'hir>,
2765 /// An item within an `extern` block.
2766 #[derive(Debug, HashStable_Generic)]
2767 pub enum ForeignItemKind<'hir> {
2768 /// A foreign function.
2769 Fn(&'hir FnDecl<'hir>, &'hir [Ident], Generics<'hir>),
2770 /// A foreign static item (`static ext: u8`).
2771 Static(&'hir Ty<'hir>, Mutability),
2776 /// A variable captured by a closure.
2777 #[derive(Debug, Copy, Clone, Encodable, HashStable_Generic)]
2779 // First span where it is accessed (there can be multiple).
2783 // The TraitCandidate's import_ids is empty if the trait is defined in the same module, and
2784 // has length > 0 if the trait is found through an chain of imports, starting with the
2785 // import/use statement in the scope where the trait is used.
2786 #[derive(Encodable, Decodable, Clone, Debug)]
2787 pub struct TraitCandidate {
2789 pub import_ids: SmallVec<[LocalDefId; 1]>,
2792 #[derive(Copy, Clone, Debug, HashStable_Generic)]
2793 pub enum Node<'hir> {
2794 Param(&'hir Param<'hir>),
2795 Item(&'hir Item<'hir>),
2796 ForeignItem(&'hir ForeignItem<'hir>),
2797 TraitItem(&'hir TraitItem<'hir>),
2798 ImplItem(&'hir ImplItem<'hir>),
2799 Variant(&'hir Variant<'hir>),
2800 Field(&'hir StructField<'hir>),
2801 AnonConst(&'hir AnonConst),
2802 Expr(&'hir Expr<'hir>),
2803 Stmt(&'hir Stmt<'hir>),
2804 PathSegment(&'hir PathSegment<'hir>),
2806 TraitRef(&'hir TraitRef<'hir>),
2807 Binding(&'hir Pat<'hir>),
2808 Pat(&'hir Pat<'hir>),
2809 Arm(&'hir Arm<'hir>),
2810 Block(&'hir Block<'hir>),
2811 Local(&'hir Local<'hir>),
2812 MacroDef(&'hir MacroDef<'hir>),
2814 /// `Ctor` refers to the constructor of an enum variant or struct. Only tuple or unit variants
2815 /// with synthesized constructors.
2816 Ctor(&'hir VariantData<'hir>),
2818 Lifetime(&'hir Lifetime),
2819 GenericParam(&'hir GenericParam<'hir>),
2820 Visibility(&'hir Visibility<'hir>),
2822 Crate(&'hir CrateItem<'hir>),
2825 impl<'hir> Node<'hir> {
2826 pub fn ident(&self) -> Option<Ident> {
2828 Node::TraitItem(TraitItem { ident, .. })
2829 | Node::ImplItem(ImplItem { ident, .. })
2830 | Node::ForeignItem(ForeignItem { ident, .. })
2831 | Node::Field(StructField { ident, .. })
2832 | Node::Variant(Variant { ident, .. })
2833 | Node::MacroDef(MacroDef { ident, .. })
2834 | Node::Item(Item { ident, .. }) => Some(*ident),
2839 pub fn fn_decl(&self) -> Option<&FnDecl<'hir>> {
2841 Node::TraitItem(TraitItem { kind: TraitItemKind::Fn(fn_sig, _), .. })
2842 | Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(fn_sig, _), .. })
2843 | Node::Item(Item { kind: ItemKind::Fn(fn_sig, _, _), .. }) => Some(fn_sig.decl),
2844 Node::ForeignItem(ForeignItem { kind: ForeignItemKind::Fn(fn_decl, _, _), .. }) => {
2851 pub fn body_id(&self) -> Option<BodyId> {
2853 Node::TraitItem(TraitItem {
2854 kind: TraitItemKind::Fn(_, TraitFn::Provided(body_id)),
2857 | Node::ImplItem(ImplItem { kind: ImplItemKind::Fn(_, body_id), .. })
2858 | Node::Item(Item { kind: ItemKind::Fn(.., body_id), .. }) => Some(*body_id),
2863 pub fn generics(&self) -> Option<&'hir Generics<'hir>> {
2865 Node::TraitItem(TraitItem { generics, .. })
2866 | Node::ImplItem(ImplItem { generics, .. }) => Some(generics),
2867 Node::Item(item) => item.kind.generics(),
2872 pub fn hir_id(&self) -> Option<HirId> {
2874 Node::Item(Item { hir_id, .. })
2875 | Node::ForeignItem(ForeignItem { hir_id, .. })
2876 | Node::TraitItem(TraitItem { hir_id, .. })
2877 | Node::ImplItem(ImplItem { hir_id, .. })
2878 | Node::Field(StructField { hir_id, .. })
2879 | Node::AnonConst(AnonConst { hir_id, .. })
2880 | Node::Expr(Expr { hir_id, .. })
2881 | Node::Stmt(Stmt { hir_id, .. })
2882 | Node::Ty(Ty { hir_id, .. })
2883 | Node::Binding(Pat { hir_id, .. })
2884 | Node::Pat(Pat { hir_id, .. })
2885 | Node::Arm(Arm { hir_id, .. })
2886 | Node::Block(Block { hir_id, .. })
2887 | Node::Local(Local { hir_id, .. })
2888 | Node::MacroDef(MacroDef { hir_id, .. })
2889 | Node::Lifetime(Lifetime { hir_id, .. })
2890 | Node::Param(Param { hir_id, .. })
2891 | Node::GenericParam(GenericParam { hir_id, .. }) => Some(*hir_id),
2892 Node::TraitRef(TraitRef { hir_ref_id, .. }) => Some(*hir_ref_id),
2893 Node::PathSegment(PathSegment { hir_id, .. }) => *hir_id,
2894 Node::Variant(Variant { id, .. }) => Some(*id),
2895 Node::Ctor(variant) => variant.ctor_hir_id(),
2896 Node::Crate(_) | Node::Visibility(_) => None,