1 //! The Rust abstract syntax tree module.
3 //! This module contains common structures forming the language AST.
4 //! Two main entities in the module are [`Item`] (which represents an AST element with
5 //! additional metadata), and [`ItemKind`] (which represents a concrete type and contains
6 //! information specific to the type of the item).
8 //! Other module items worth mentioning:
9 //! - [`Ty`] and [`TyKind`]: A parsed Rust type.
10 //! - [`Expr`] and [`ExprKind`]: A parsed Rust expression.
11 //! - [`Pat`] and [`PatKind`]: A parsed Rust pattern. Patterns are often dual to expressions.
12 //! - [`Stmt`] and [`StmtKind`]: An executable action that does not return a value.
13 //! - [`FnDecl`], [`FnHeader`] and [`Param`]: Metadata associated with a function declaration.
14 //! - [`Generics`], [`GenericParam`], [`WhereClause`]: Metadata associated with generic parameters.
15 //! - [`EnumDef`] and [`Variant`]: Enum declaration.
16 //! - [`Lit`] and [`LitKind`]: Literal expressions.
17 //! - [`MacroDef`], [`MacStmtStyle`], [`MacCall`], [`MacDelimiter`]: Macro definition and invocation.
18 //! - [`Attribute`]: Metadata associated with item.
19 //! - [`UnOp`], [`BinOp`], and [`BinOpKind`]: Unary and binary operators.
21 pub use crate::util::parser::ExprPrecedence;
22 pub use GenericArgs::*;
23 pub use UnsafeSource::*;
26 use crate::token::{self, CommentKind, Delimiter};
27 use crate::tokenstream::{DelimSpan, LazyAttrTokenStream, TokenStream};
28 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
29 use rustc_data_structures::stack::ensure_sufficient_stack;
30 use rustc_data_structures::sync::Lrc;
31 use rustc_macros::HashStable_Generic;
32 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
33 use rustc_span::source_map::{respan, Spanned};
34 use rustc_span::symbol::{kw, sym, Ident, Symbol};
35 use rustc_span::{Span, DUMMY_SP};
36 use std::convert::TryFrom;
39 use thin_vec::{thin_vec, ThinVec};
41 /// A "Label" is an identifier of some point in sources,
42 /// e.g. in the following code:
50 /// `'outer` is a label.
51 #[derive(Clone, Encodable, Decodable, Copy, HashStable_Generic, Eq, PartialEq)]
56 impl fmt::Debug for Label {
57 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
58 write!(f, "label({:?})", self.ident)
62 /// A "Lifetime" is an annotation of the scope in which variable
63 /// can be used, e.g. `'a` in `&'a i32`.
64 #[derive(Clone, Encodable, Decodable, Copy, PartialEq, Eq)]
70 impl fmt::Debug for Lifetime {
71 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
72 write!(f, "lifetime({}: {})", self.id, self)
76 impl fmt::Display for Lifetime {
77 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
78 write!(f, "{}", self.ident.name)
82 /// A "Path" is essentially Rust's notion of a name.
84 /// It's represented as a sequence of identifiers,
85 /// along with a bunch of supporting information.
87 /// E.g., `std::cmp::PartialEq`.
88 #[derive(Clone, Encodable, Decodable, Debug)]
91 /// The segments in the path: the things separated by `::`.
92 /// Global paths begin with `kw::PathRoot`.
93 pub segments: ThinVec<PathSegment>,
94 pub tokens: Option<LazyAttrTokenStream>,
97 impl PartialEq<Symbol> for Path {
99 fn eq(&self, symbol: &Symbol) -> bool {
100 self.segments.len() == 1 && { self.segments[0].ident.name == *symbol }
104 impl<CTX: rustc_span::HashStableContext> HashStable<CTX> for Path {
105 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
106 self.segments.len().hash_stable(hcx, hasher);
107 for segment in &self.segments {
108 segment.ident.hash_stable(hcx, hasher);
114 // Convert a span and an identifier to the corresponding
116 pub fn from_ident(ident: Ident) -> Path {
117 Path { segments: thin_vec![PathSegment::from_ident(ident)], span: ident.span, tokens: None }
120 pub fn is_global(&self) -> bool {
121 !self.segments.is_empty() && self.segments[0].ident.name == kw::PathRoot
125 /// A segment of a path: an identifier, an optional lifetime, and a set of types.
127 /// E.g., `std`, `String` or `Box<T>`.
128 #[derive(Clone, Encodable, Decodable, Debug)]
129 pub struct PathSegment {
130 /// The identifier portion of this path segment.
135 /// Type/lifetime parameters attached to this path. They come in
136 /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`.
137 /// `None` means that no parameter list is supplied (`Path`),
138 /// `Some` means that parameter list is supplied (`Path<X, Y>`)
139 /// but it can be empty (`Path<>`).
140 /// `P` is used as a size optimization for the common case with no parameters.
141 pub args: Option<P<GenericArgs>>,
145 pub fn from_ident(ident: Ident) -> Self {
146 PathSegment { ident, id: DUMMY_NODE_ID, args: None }
149 pub fn path_root(span: Span) -> Self {
150 PathSegment::from_ident(Ident::new(kw::PathRoot, span))
153 pub fn span(&self) -> Span {
155 Some(args) => self.ident.span.to(args.span()),
156 None => self.ident.span,
161 /// The arguments of a path segment.
163 /// E.g., `<A, B>` as in `Foo<A, B>` or `(A, B)` as in `Foo(A, B)`.
164 #[derive(Clone, Encodable, Decodable, Debug)]
165 pub enum GenericArgs {
166 /// The `<'a, A, B, C>` in `foo::bar::baz::<'a, A, B, C>`.
167 AngleBracketed(AngleBracketedArgs),
168 /// The `(A, B)` and `C` in `Foo(A, B) -> C`.
169 Parenthesized(ParenthesizedArgs),
173 pub fn is_angle_bracketed(&self) -> bool {
174 matches!(self, AngleBracketed(..))
177 pub fn span(&self) -> Span {
179 AngleBracketed(data) => data.span,
180 Parenthesized(data) => data.span,
185 /// Concrete argument in the sequence of generic args.
186 #[derive(Clone, Encodable, Decodable, Debug)]
187 pub enum GenericArg {
188 /// `'a` in `Foo<'a>`
190 /// `Bar` in `Foo<Bar>`
197 pub fn span(&self) -> Span {
199 GenericArg::Lifetime(lt) => lt.ident.span,
200 GenericArg::Type(ty) => ty.span,
201 GenericArg::Const(ct) => ct.value.span,
206 /// A path like `Foo<'a, T>`.
207 #[derive(Clone, Encodable, Decodable, Debug, Default)]
208 pub struct AngleBracketedArgs {
209 /// The overall span.
211 /// The comma separated parts in the `<...>`.
212 pub args: Vec<AngleBracketedArg>,
215 /// Either an argument for a parameter e.g., `'a`, `Vec<u8>`, `0`,
216 /// or a constraint on an associated item, e.g., `Item = String` or `Item: Bound`.
217 #[derive(Clone, Encodable, Decodable, Debug)]
218 pub enum AngleBracketedArg {
219 /// Argument for a generic parameter.
221 /// Constraint for an associated item.
222 Constraint(AssocConstraint),
225 impl AngleBracketedArg {
226 pub fn span(&self) -> Span {
228 AngleBracketedArg::Arg(arg) => arg.span(),
229 AngleBracketedArg::Constraint(constraint) => constraint.span,
234 impl Into<Option<P<GenericArgs>>> for AngleBracketedArgs {
235 fn into(self) -> Option<P<GenericArgs>> {
236 Some(P(GenericArgs::AngleBracketed(self)))
240 impl Into<Option<P<GenericArgs>>> for ParenthesizedArgs {
241 fn into(self) -> Option<P<GenericArgs>> {
242 Some(P(GenericArgs::Parenthesized(self)))
246 /// A path like `Foo(A, B) -> C`.
247 #[derive(Clone, Encodable, Decodable, Debug)]
248 pub struct ParenthesizedArgs {
256 pub inputs: Vec<P<Ty>>,
262 pub inputs_span: Span,
268 impl ParenthesizedArgs {
269 pub fn as_angle_bracketed_args(&self) -> AngleBracketedArgs {
274 .map(|input| AngleBracketedArg::Arg(GenericArg::Type(input)))
276 AngleBracketedArgs { span: self.inputs_span, args }
280 pub use crate::node_id::{NodeId, CRATE_NODE_ID, DUMMY_NODE_ID};
282 /// A modifier on a bound, e.g., `?Trait` or `~const Trait`.
284 /// Negative bounds should also be handled here.
285 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Decodable, Debug)]
286 pub enum TraitBoundModifier {
298 // This parses but will be rejected during AST validation.
302 /// The AST represents all type param bounds as types.
303 /// `typeck::collect::compute_bounds` matches these against
304 /// the "special" built-in traits (see `middle::lang_items`) and
305 /// detects `Copy`, `Send` and `Sync`.
306 #[derive(Clone, Encodable, Decodable, Debug)]
307 pub enum GenericBound {
308 Trait(PolyTraitRef, TraitBoundModifier),
313 pub fn span(&self) -> Span {
315 GenericBound::Trait(t, ..) => t.span,
316 GenericBound::Outlives(l) => l.ident.span,
321 pub type GenericBounds = Vec<GenericBound>;
323 /// Specifies the enforced ordering for generic parameters. In the future,
324 /// if we wanted to relax this order, we could override `PartialEq` and
325 /// `PartialOrd`, to allow the kinds to be unordered.
326 #[derive(Hash, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
327 pub enum ParamKindOrd {
332 impl fmt::Display for ParamKindOrd {
333 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
335 ParamKindOrd::Lifetime => "lifetime".fmt(f),
336 ParamKindOrd::TypeOrConst => "type and const".fmt(f),
341 #[derive(Clone, Encodable, Decodable, Debug)]
342 pub enum GenericParamKind {
343 /// A lifetime definition (e.g., `'a: 'b + 'c + 'd`).
346 default: Option<P<Ty>>,
350 /// Span of the `const` keyword.
352 /// Optional default value for the const generic param
353 default: Option<AnonConst>,
357 #[derive(Clone, Encodable, Decodable, Debug)]
358 pub struct GenericParam {
362 pub bounds: GenericBounds,
363 pub is_placeholder: bool,
364 pub kind: GenericParamKind,
365 pub colon_span: Option<Span>,
369 pub fn span(&self) -> Span {
371 GenericParamKind::Lifetime | GenericParamKind::Type { default: None } => {
374 GenericParamKind::Type { default: Some(ty) } => self.ident.span.to(ty.span),
375 GenericParamKind::Const { kw_span, default: Some(default), .. } => {
376 kw_span.to(default.value.span)
378 GenericParamKind::Const { kw_span, default: None, ty } => kw_span.to(ty.span),
383 /// Represents lifetime, type and const parameters attached to a declaration of
384 /// a function, enum, trait, etc.
385 #[derive(Clone, Encodable, Decodable, Debug)]
386 pub struct Generics {
387 pub params: Vec<GenericParam>,
388 pub where_clause: WhereClause,
392 impl Default for Generics {
393 /// Creates an instance of `Generics`.
394 fn default() -> Generics {
395 Generics { params: Vec::new(), where_clause: Default::default(), span: DUMMY_SP }
399 /// A where-clause in a definition.
400 #[derive(Clone, Encodable, Decodable, Debug)]
401 pub struct WhereClause {
402 /// `true` if we ate a `where` token: this can happen
403 /// if we parsed no predicates (e.g. `struct Foo where {}`).
404 /// This allows us to pretty-print accurately.
405 pub has_where_token: bool,
406 pub predicates: Vec<WherePredicate>,
410 impl Default for WhereClause {
411 fn default() -> WhereClause {
412 WhereClause { has_where_token: false, predicates: Vec::new(), span: DUMMY_SP }
416 /// A single predicate in a where-clause.
417 #[derive(Clone, Encodable, Decodable, Debug)]
418 pub enum WherePredicate {
419 /// A type binding (e.g., `for<'c> Foo: Send + Clone + 'c`).
420 BoundPredicate(WhereBoundPredicate),
421 /// A lifetime predicate (e.g., `'a: 'b + 'c`).
422 RegionPredicate(WhereRegionPredicate),
423 /// An equality predicate (unsupported).
424 EqPredicate(WhereEqPredicate),
427 impl WherePredicate {
428 pub fn span(&self) -> Span {
430 WherePredicate::BoundPredicate(p) => p.span,
431 WherePredicate::RegionPredicate(p) => p.span,
432 WherePredicate::EqPredicate(p) => p.span,
439 /// E.g., `for<'c> Foo: Send + Clone + 'c`.
440 #[derive(Clone, Encodable, Decodable, Debug)]
441 pub struct WhereBoundPredicate {
443 /// Any generics from a `for` binding.
444 pub bound_generic_params: Vec<GenericParam>,
445 /// The type being bounded.
446 pub bounded_ty: P<Ty>,
447 /// Trait and lifetime bounds (`Clone + Send + 'static`).
448 pub bounds: GenericBounds,
451 /// A lifetime predicate.
453 /// E.g., `'a: 'b + 'c`.
454 #[derive(Clone, Encodable, Decodable, Debug)]
455 pub struct WhereRegionPredicate {
457 pub lifetime: Lifetime,
458 pub bounds: GenericBounds,
461 /// An equality predicate (unsupported).
464 #[derive(Clone, Encodable, Decodable, Debug)]
465 pub struct WhereEqPredicate {
471 #[derive(Clone, Encodable, Decodable, Debug)]
474 pub items: Vec<P<Item>>,
476 /// Must be equal to `CRATE_NODE_ID` after the crate root is expanded, but may hold
477 /// expansion placeholders or an unassigned value (`DUMMY_NODE_ID`) before that.
479 pub is_placeholder: bool,
482 /// Possible values inside of compile-time attribute lists.
484 /// E.g., the '..' in `#[name(..)]`.
485 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
486 pub enum NestedMetaItem {
487 /// A full MetaItem, for recursive meta items.
491 /// E.g., `"foo"`, `64`, `true`.
495 /// A spanned compile-time attribute item.
497 /// E.g., `#[test]`, `#[derive(..)]`, `#[rustfmt::skip]` or `#[feature = "foo"]`.
498 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
499 pub struct MetaItem {
501 pub kind: MetaItemKind,
505 /// A compile-time attribute item.
507 /// E.g., `#[test]`, `#[derive(..)]` or `#[feature = "foo"]`.
508 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
509 pub enum MetaItemKind {
512 /// E.g., `test` as in `#[test]`.
516 /// E.g., `derive(..)` as in `#[derive(..)]`.
517 List(Vec<NestedMetaItem>),
518 /// Name value meta item.
520 /// E.g., `feature = "foo"` as in `#[feature = "foo"]`.
524 /// A block (`{ .. }`).
526 /// E.g., `{ .. }` as in `fn foo() { .. }`.
527 #[derive(Clone, Encodable, Decodable, Debug)]
529 /// The statements in the block.
530 pub stmts: Vec<Stmt>,
532 /// Distinguishes between `unsafe { ... }` and `{ ... }`.
533 pub rules: BlockCheckMode,
535 pub tokens: Option<LazyAttrTokenStream>,
536 /// The following *isn't* a parse error, but will cause multiple errors in following stages.
543 pub could_be_bare_literal: bool,
548 /// Patterns appear in match statements and some other contexts, such as `let` and `if let`.
549 #[derive(Clone, Encodable, Decodable, Debug)]
554 pub tokens: Option<LazyAttrTokenStream>,
558 /// Attempt reparsing the pattern as a type.
559 /// This is intended for use by diagnostics.
560 pub fn to_ty(&self) -> Option<P<Ty>> {
561 let kind = match &self.kind {
562 // In a type expression `_` is an inference variable.
563 PatKind::Wild => TyKind::Infer,
564 // An IDENT pattern with no binding mode would be valid as path to a type. E.g. `u32`.
565 PatKind::Ident(BindingAnnotation::NONE, ident, None) => {
566 TyKind::Path(None, Path::from_ident(*ident))
568 PatKind::Path(qself, path) => TyKind::Path(qself.clone(), path.clone()),
569 PatKind::MacCall(mac) => TyKind::MacCall(mac.clone()),
570 // `&mut? P` can be reinterpreted as `&mut? T` where `T` is `P` reparsed as a type.
571 PatKind::Ref(pat, mutbl) => {
572 pat.to_ty().map(|ty| TyKind::Rptr(None, MutTy { ty, mutbl: *mutbl }))?
574 // A slice/array pattern `[P]` can be reparsed as `[T]`, an unsized array,
575 // when `P` can be reparsed as a type `T`.
576 PatKind::Slice(pats) if pats.len() == 1 => pats[0].to_ty().map(TyKind::Slice)?,
577 // A tuple pattern `(P0, .., Pn)` can be reparsed as `(T0, .., Tn)`
578 // assuming `T0` to `Tn` are all syntactically valid as types.
579 PatKind::Tuple(pats) => {
580 let mut tys = Vec::with_capacity(pats.len());
581 // FIXME(#48994) - could just be collected into an Option<Vec>
583 tys.push(pat.to_ty()?);
590 Some(P(Ty { kind, id: self.id, span: self.span, tokens: None }))
593 /// Walk top-down and call `it` in each place where a pattern occurs
594 /// starting with the root pattern `walk` is called on. If `it` returns
595 /// false then we will descend no further but siblings will be processed.
596 pub fn walk(&self, it: &mut impl FnMut(&Pat) -> bool) {
602 // Walk into the pattern associated with `Ident` (if any).
603 PatKind::Ident(_, _, Some(p)) => p.walk(it),
605 // Walk into each field of struct.
606 PatKind::Struct(_, _, fields, _) => fields.iter().for_each(|field| field.pat.walk(it)),
608 // Sequence of patterns.
609 PatKind::TupleStruct(_, _, s)
612 | PatKind::Or(s) => s.iter().for_each(|p| p.walk(it)),
614 // Trivial wrappers over inner patterns.
615 PatKind::Box(s) | PatKind::Ref(s, _) | PatKind::Paren(s) => s.walk(it),
617 // These patterns do not contain subpatterns, skip.
624 | PatKind::MacCall(_) => {}
628 /// Is this a `..` pattern?
629 pub fn is_rest(&self) -> bool {
630 matches!(self.kind, PatKind::Rest)
634 /// A single field in a struct pattern.
636 /// Patterns like the fields of `Foo { x, ref y, ref mut z }`
637 /// are treated the same as `x: x, y: ref y, z: ref mut z`,
638 /// except when `is_shorthand` is true.
639 #[derive(Clone, Encodable, Decodable, Debug)]
640 pub struct PatField {
641 /// The identifier for the field.
643 /// The pattern the field is destructured to.
645 pub is_shorthand: bool,
649 pub is_placeholder: bool,
652 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
653 #[derive(Encodable, Decodable, HashStable_Generic)]
659 impl From<bool> for ByRef {
660 fn from(b: bool) -> ByRef {
668 /// Explicit binding annotations given in the HIR for a binding. Note
669 /// that this is not the final binding *mode* that we infer after type
671 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
672 #[derive(Encodable, Decodable, HashStable_Generic)]
673 pub struct BindingAnnotation(pub ByRef, pub Mutability);
675 impl BindingAnnotation {
676 pub const NONE: Self = Self(ByRef::No, Mutability::Not);
677 pub const REF: Self = Self(ByRef::Yes, Mutability::Not);
678 pub const MUT: Self = Self(ByRef::No, Mutability::Mut);
679 pub const REF_MUT: Self = Self(ByRef::Yes, Mutability::Mut);
681 pub fn prefix_str(self) -> &'static str {
686 Self::REF_MUT => "ref mut ",
691 #[derive(Clone, Encodable, Decodable, Debug)]
694 Included(RangeSyntax),
699 #[derive(Clone, Encodable, Decodable, Debug)]
700 pub enum RangeSyntax {
707 /// All the different flavors of pattern that Rust recognizes.
708 #[derive(Clone, Encodable, Decodable, Debug)]
710 /// Represents a wildcard pattern (`_`).
713 /// A `PatKind::Ident` may either be a new bound variable (`ref mut binding @ OPT_SUBPATTERN`),
714 /// or a unit struct/variant pattern, or a const pattern (in the last two cases the third
715 /// field must be `None`). Disambiguation cannot be done with parser alone, so it happens
716 /// during name resolution.
717 Ident(BindingAnnotation, Ident, Option<P<Pat>>),
719 /// A struct or struct variant pattern (e.g., `Variant {x, y, ..}`).
720 /// The `bool` is `true` in the presence of a `..`.
721 Struct(Option<P<QSelf>>, Path, Vec<PatField>, /* recovered */ bool),
723 /// A tuple struct/variant pattern (`Variant(x, y, .., z)`).
724 TupleStruct(Option<P<QSelf>>, Path, Vec<P<Pat>>),
726 /// An or-pattern `A | B | C`.
727 /// Invariant: `pats.len() >= 2`.
730 /// A possibly qualified path pattern.
731 /// Unqualified path patterns `A::B::C` can legally refer to variants, structs, constants
732 /// or associated constants. Qualified path patterns `<A>::B::C`/`<A as Trait>::B::C` can
733 /// only legally refer to associated constants.
734 Path(Option<P<QSelf>>, Path),
736 /// A tuple pattern (`(a, b)`).
742 /// A reference pattern (e.g., `&mut (a, b)`).
743 Ref(P<Pat>, Mutability),
748 /// A range pattern (e.g., `1...2`, `1..2`, `1..`, `..2`, `1..=2`, `..=2`).
749 Range(Option<P<Expr>>, Option<P<Expr>>, Spanned<RangeEnd>),
751 /// A slice pattern `[a, b, c]`.
754 /// A rest pattern `..`.
756 /// Syntactically it is valid anywhere.
758 /// Semantically however, it only has meaning immediately inside:
759 /// - a slice pattern: `[a, .., b]`,
760 /// - a binding pattern immediately inside a slice pattern: `[a, r @ ..]`,
761 /// - a tuple pattern: `(a, .., b)`,
762 /// - a tuple struct/variant pattern: `$path(a, .., b)`.
764 /// In all of these cases, an additional restriction applies,
765 /// only one rest pattern may occur in the pattern sequences.
768 /// Parentheses in patterns used for grouping (i.e., `(PAT)`).
771 /// A macro pattern; pre-expansion.
775 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Copy)]
776 #[derive(HashStable_Generic, Encodable, Decodable)]
777 pub enum Mutability {
783 pub fn invert(self) -> Self {
785 Mutability::Mut => Mutability::Not,
786 Mutability::Not => Mutability::Mut,
790 pub fn prefix_str(&self) -> &'static str {
792 Mutability::Mut => "mut ",
793 Mutability::Not => "",
798 /// The kind of borrow in an `AddrOf` expression,
799 /// e.g., `&place` or `&raw const place`.
800 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
801 #[derive(Encodable, Decodable, HashStable_Generic)]
802 pub enum BorrowKind {
803 /// A normal borrow, `&$expr` or `&mut $expr`.
804 /// The resulting type is either `&'a T` or `&'a mut T`
805 /// where `T = typeof($expr)` and `'a` is some lifetime.
807 /// A raw borrow, `&raw const $expr` or `&raw mut $expr`.
808 /// The resulting type is either `*const T` or `*mut T`
809 /// where `T = typeof($expr)`.
813 #[derive(Clone, PartialEq, Encodable, Decodable, Debug, Copy)]
815 /// The `+` operator (addition)
817 /// The `-` operator (subtraction)
819 /// The `*` operator (multiplication)
821 /// The `/` operator (division)
823 /// The `%` operator (modulus)
825 /// The `&&` operator (logical and)
827 /// The `||` operator (logical or)
829 /// The `^` operator (bitwise xor)
831 /// The `&` operator (bitwise and)
833 /// The `|` operator (bitwise or)
835 /// The `<<` operator (shift left)
837 /// The `>>` operator (shift right)
839 /// The `==` operator (equality)
841 /// The `<` operator (less than)
843 /// The `<=` operator (less than or equal to)
845 /// The `!=` operator (not equal to)
847 /// The `>=` operator (greater than or equal to)
849 /// The `>` operator (greater than)
854 pub fn to_string(&self) -> &'static str {
877 pub fn lazy(&self) -> bool {
878 matches!(self, BinOpKind::And | BinOpKind::Or)
881 pub fn is_comparison(&self) -> bool {
883 // Note for developers: please keep this as is;
884 // we want compilation to fail if another variant is added.
886 Eq | Lt | Le | Ne | Gt | Ge => true,
887 And | Or | Add | Sub | Mul | Div | Rem | BitXor | BitAnd | BitOr | Shl | Shr => false,
892 pub type BinOp = Spanned<BinOpKind>;
896 /// Note that `&data` is not an operator, it's an `AddrOf` expression.
897 #[derive(Clone, Encodable, Decodable, Debug, Copy)]
899 /// The `*` operator for dereferencing
901 /// The `!` operator for logical inversion
903 /// The `-` operator for negation
908 pub fn to_string(op: UnOp) -> &'static str {
918 #[derive(Clone, Encodable, Decodable, Debug)]
926 pub fn has_trailing_semicolon(&self) -> bool {
928 StmtKind::Semi(_) => true,
929 StmtKind::MacCall(mac) => matches!(mac.style, MacStmtStyle::Semicolon),
934 /// Converts a parsed `Stmt` to a `Stmt` with
935 /// a trailing semicolon.
937 /// This only modifies the parsed AST struct, not the attached
938 /// `LazyAttrTokenStream`. The parser is responsible for calling
939 /// `ToAttrTokenStream::add_trailing_semi` when there is actually
940 /// a semicolon in the tokenstream.
941 pub fn add_trailing_semicolon(mut self) -> Self {
942 self.kind = match self.kind {
943 StmtKind::Expr(expr) => StmtKind::Semi(expr),
944 StmtKind::MacCall(mac) => {
945 StmtKind::MacCall(mac.map(|MacCallStmt { mac, style: _, attrs, tokens }| {
946 MacCallStmt { mac, style: MacStmtStyle::Semicolon, attrs, tokens }
955 pub fn is_item(&self) -> bool {
956 matches!(self.kind, StmtKind::Item(_))
959 pub fn is_expr(&self) -> bool {
960 matches!(self.kind, StmtKind::Expr(_))
964 #[derive(Clone, Encodable, Decodable, Debug)]
966 /// A local (let) binding.
968 /// An item definition.
970 /// Expr without trailing semi-colon.
972 /// Expr with a trailing semi-colon.
974 /// Just a trailing semi-colon.
977 MacCall(P<MacCallStmt>),
980 #[derive(Clone, Encodable, Decodable, Debug)]
981 pub struct MacCallStmt {
983 pub style: MacStmtStyle,
985 pub tokens: Option<LazyAttrTokenStream>,
988 #[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug)]
989 pub enum MacStmtStyle {
990 /// The macro statement had a trailing semicolon (e.g., `foo! { ... };`
991 /// `foo!(...);`, `foo![...];`).
993 /// The macro statement had braces (e.g., `foo! { ... }`).
995 /// The macro statement had parentheses or brackets and no semicolon (e.g.,
996 /// `foo!(...)`). All of these will end up being converted into macro
1001 /// Local represents a `let` statement, e.g., `let <pat>:<ty> = <expr>;`.
1002 #[derive(Clone, Encodable, Decodable, Debug)]
1006 pub ty: Option<P<Ty>>,
1007 pub kind: LocalKind,
1010 pub tokens: Option<LazyAttrTokenStream>,
1013 #[derive(Clone, Encodable, Decodable, Debug)]
1014 pub enum LocalKind {
1015 /// Local declaration.
1016 /// Example: `let x;`
1018 /// Local declaration with an initializer.
1019 /// Example: `let x = y;`
1021 /// Local declaration with an initializer and an `else` clause.
1022 /// Example: `let Some(x) = y else { return };`
1023 InitElse(P<Expr>, P<Block>),
1027 pub fn init(&self) -> Option<&Expr> {
1030 Self::Init(i) | Self::InitElse(i, _) => Some(i),
1034 pub fn init_else_opt(&self) -> Option<(&Expr, Option<&Block>)> {
1037 Self::Init(init) => Some((init, None)),
1038 Self::InitElse(init, els) => Some((init, Some(els))),
1043 /// An arm of a 'match'.
1045 /// E.g., `0..=10 => { println!("match!") }` as in
1049 /// 0..=10 => { println!("match!") },
1050 /// _ => { println!("no match!") },
1053 #[derive(Clone, Encodable, Decodable, Debug)]
1056 /// Match arm pattern, e.g. `10` in `match foo { 10 => {}, _ => {} }`
1058 /// Match arm guard, e.g. `n > 10` in `match foo { n if n > 10 => {}, _ => {} }`
1059 pub guard: Option<P<Expr>>,
1064 pub is_placeholder: bool,
1067 /// A single field in a struct expression, e.g. `x: value` and `y` in `Foo { x: value, y }`.
1068 #[derive(Clone, Encodable, Decodable, Debug)]
1069 pub struct ExprField {
1075 pub is_shorthand: bool,
1076 pub is_placeholder: bool,
1079 #[derive(Clone, PartialEq, Encodable, Decodable, Debug, Copy)]
1080 pub enum BlockCheckMode {
1082 Unsafe(UnsafeSource),
1085 #[derive(Clone, PartialEq, Encodable, Decodable, Debug, Copy)]
1086 pub enum UnsafeSource {
1091 /// A constant (expression) that's not an item or associated item,
1092 /// but needs its own `DefId` for type-checking, const-eval, etc.
1093 /// These are usually found nested inside types (e.g., array lengths)
1094 /// or expressions (e.g., repeat counts), and also used to define
1095 /// explicit discriminant values for enum variants.
1096 #[derive(Clone, Encodable, Decodable, Debug)]
1097 pub struct AnonConst {
1103 #[derive(Clone, Encodable, Decodable, Debug)]
1109 pub tokens: Option<LazyAttrTokenStream>,
1113 /// Is this expr either `N`, or `{ N }`.
1115 /// If this is not the case, name resolution does not resolve `N` when using
1116 /// `min_const_generics` as more complex expressions are not supported.
1117 pub fn is_potential_trivial_const_param(&self) -> bool {
1118 let this = if let ExprKind::Block(block, None) = &self.kind
1119 && block.stmts.len() == 1
1120 && let StmtKind::Expr(expr) = &block.stmts[0].kind
1127 if let ExprKind::Path(None, path) = &this.kind
1128 && path.segments.len() == 1
1129 && path.segments[0].args.is_none()
1137 pub fn to_bound(&self) -> Option<GenericBound> {
1139 ExprKind::Path(None, path) => Some(GenericBound::Trait(
1140 PolyTraitRef::new(Vec::new(), path.clone(), self.span),
1141 TraitBoundModifier::None,
1147 pub fn peel_parens(&self) -> &Expr {
1148 let mut expr = self;
1149 while let ExprKind::Paren(inner) = &expr.kind {
1155 /// Attempts to reparse as `Ty` (for diagnostic purposes).
1156 pub fn to_ty(&self) -> Option<P<Ty>> {
1157 let kind = match &self.kind {
1158 // Trivial conversions.
1159 ExprKind::Path(qself, path) => TyKind::Path(qself.clone(), path.clone()),
1160 ExprKind::MacCall(mac) => TyKind::MacCall(mac.clone()),
1162 ExprKind::Paren(expr) => expr.to_ty().map(TyKind::Paren)?,
1164 ExprKind::AddrOf(BorrowKind::Ref, mutbl, expr) => {
1165 expr.to_ty().map(|ty| TyKind::Rptr(None, MutTy { ty, mutbl: *mutbl }))?
1168 ExprKind::Repeat(expr, expr_len) => {
1169 expr.to_ty().map(|ty| TyKind::Array(ty, expr_len.clone()))?
1172 ExprKind::Array(exprs) if exprs.len() == 1 => exprs[0].to_ty().map(TyKind::Slice)?,
1174 ExprKind::Tup(exprs) => {
1175 let tys = exprs.iter().map(|expr| expr.to_ty()).collect::<Option<Vec<_>>>()?;
1179 // If binary operator is `Add` and both `lhs` and `rhs` are trait bounds,
1180 // then type of result is trait object.
1181 // Otherwise we don't assume the result type.
1182 ExprKind::Binary(binop, lhs, rhs) if binop.node == BinOpKind::Add => {
1183 if let (Some(lhs), Some(rhs)) = (lhs.to_bound(), rhs.to_bound()) {
1184 TyKind::TraitObject(vec![lhs, rhs], TraitObjectSyntax::None)
1190 ExprKind::Underscore => TyKind::Infer,
1192 // This expression doesn't look like a type syntactically.
1196 Some(P(Ty { kind, id: self.id, span: self.span, tokens: None }))
1199 pub fn precedence(&self) -> ExprPrecedence {
1201 ExprKind::Box(_) => ExprPrecedence::Box,
1202 ExprKind::Array(_) => ExprPrecedence::Array,
1203 ExprKind::ConstBlock(_) => ExprPrecedence::ConstBlock,
1204 ExprKind::Call(..) => ExprPrecedence::Call,
1205 ExprKind::MethodCall(..) => ExprPrecedence::MethodCall,
1206 ExprKind::Tup(_) => ExprPrecedence::Tup,
1207 ExprKind::Binary(op, ..) => ExprPrecedence::Binary(op.node),
1208 ExprKind::Unary(..) => ExprPrecedence::Unary,
1209 ExprKind::Lit(_) | ExprKind::IncludedBytes(..) => ExprPrecedence::Lit,
1210 ExprKind::Type(..) | ExprKind::Cast(..) => ExprPrecedence::Cast,
1211 ExprKind::Let(..) => ExprPrecedence::Let,
1212 ExprKind::If(..) => ExprPrecedence::If,
1213 ExprKind::While(..) => ExprPrecedence::While,
1214 ExprKind::ForLoop(..) => ExprPrecedence::ForLoop,
1215 ExprKind::Loop(..) => ExprPrecedence::Loop,
1216 ExprKind::Match(..) => ExprPrecedence::Match,
1217 ExprKind::Closure(..) => ExprPrecedence::Closure,
1218 ExprKind::Block(..) => ExprPrecedence::Block,
1219 ExprKind::TryBlock(..) => ExprPrecedence::TryBlock,
1220 ExprKind::Async(..) => ExprPrecedence::Async,
1221 ExprKind::Await(..) => ExprPrecedence::Await,
1222 ExprKind::Assign(..) => ExprPrecedence::Assign,
1223 ExprKind::AssignOp(..) => ExprPrecedence::AssignOp,
1224 ExprKind::Field(..) => ExprPrecedence::Field,
1225 ExprKind::Index(..) => ExprPrecedence::Index,
1226 ExprKind::Range(..) => ExprPrecedence::Range,
1227 ExprKind::Underscore => ExprPrecedence::Path,
1228 ExprKind::Path(..) => ExprPrecedence::Path,
1229 ExprKind::AddrOf(..) => ExprPrecedence::AddrOf,
1230 ExprKind::Break(..) => ExprPrecedence::Break,
1231 ExprKind::Continue(..) => ExprPrecedence::Continue,
1232 ExprKind::Ret(..) => ExprPrecedence::Ret,
1233 ExprKind::InlineAsm(..) => ExprPrecedence::InlineAsm,
1234 ExprKind::MacCall(..) => ExprPrecedence::Mac,
1235 ExprKind::Struct(..) => ExprPrecedence::Struct,
1236 ExprKind::Repeat(..) => ExprPrecedence::Repeat,
1237 ExprKind::Paren(..) => ExprPrecedence::Paren,
1238 ExprKind::Try(..) => ExprPrecedence::Try,
1239 ExprKind::Yield(..) => ExprPrecedence::Yield,
1240 ExprKind::Yeet(..) => ExprPrecedence::Yeet,
1241 ExprKind::Err => ExprPrecedence::Err,
1245 pub fn take(&mut self) -> Self {
1250 kind: ExprKind::Err,
1252 attrs: AttrVec::new(),
1258 // To a first-order approximation, is this a pattern
1259 pub fn is_approximately_pattern(&self) -> bool {
1260 match &self.peel_parens().kind {
1262 | ExprKind::Array(_)
1263 | ExprKind::Call(_, _)
1266 | ExprKind::Range(_, _, _)
1267 | ExprKind::Underscore
1268 | ExprKind::Path(_, _)
1269 | ExprKind::Struct(_) => true,
1275 #[derive(Clone, Encodable, Decodable, Debug)]
1276 pub struct Closure {
1277 pub binder: ClosureBinder,
1278 pub capture_clause: CaptureBy,
1279 pub asyncness: Async,
1280 pub movability: Movability,
1281 pub fn_decl: P<FnDecl>,
1283 /// The span of the argument block `|...|`.
1284 pub fn_decl_span: Span,
1287 /// Limit types of a range (inclusive or exclusive)
1288 #[derive(Copy, Clone, PartialEq, Encodable, Decodable, Debug)]
1289 pub enum RangeLimits {
1290 /// Inclusive at the beginning, exclusive at the end
1292 /// Inclusive at the beginning and end
1296 /// A method call (e.g. `x.foo::<Bar, Baz>(a, b, c)`).
1297 #[derive(Clone, Encodable, Decodable, Debug)]
1298 pub struct MethodCall {
1299 /// The method name and its generic arguments, e.g. `foo::<Bar, Baz>`.
1300 pub seg: PathSegment,
1301 /// The receiver, e.g. `x`.
1302 pub receiver: P<Expr>,
1303 /// The arguments, e.g. `a, b, c`.
1304 pub args: Vec<P<Expr>>,
1305 /// The span of the function, without the dot and receiver e.g. `foo::<Bar,
1310 #[derive(Clone, Encodable, Decodable, Debug)]
1311 pub enum StructRest {
1316 /// No trailing `..` or expression.
1320 #[derive(Clone, Encodable, Decodable, Debug)]
1321 pub struct StructExpr {
1322 pub qself: Option<P<QSelf>>,
1324 pub fields: Vec<ExprField>,
1325 pub rest: StructRest,
1328 #[derive(Clone, Encodable, Decodable, Debug)]
1330 /// A `box x` expression.
1332 /// An array (`[a, b, c, d]`)
1333 Array(Vec<P<Expr>>),
1334 /// Allow anonymous constants from an inline `const` block
1335 ConstBlock(AnonConst),
1338 /// The first field resolves to the function itself,
1339 /// and the second field is the list of arguments.
1340 /// This also represents calling the constructor of
1341 /// tuple-like ADTs such as tuple structs and enum variants.
1342 Call(P<Expr>, Vec<P<Expr>>),
1343 /// A method call (e.g. `x.foo::<Bar, Baz>(a, b, c)`).
1344 MethodCall(Box<MethodCall>),
1345 /// A tuple (e.g., `(a, b, c, d)`).
1347 /// A binary operation (e.g., `a + b`, `a * b`).
1348 Binary(BinOp, P<Expr>, P<Expr>),
1349 /// A unary operation (e.g., `!x`, `*x`).
1350 Unary(UnOp, P<Expr>),
1351 /// A literal (e.g., `1`, `"foo"`).
1353 /// A cast (e.g., `foo as f64`).
1354 Cast(P<Expr>, P<Ty>),
1355 /// A type ascription (e.g., `42: usize`).
1356 Type(P<Expr>, P<Ty>),
1357 /// A `let pat = expr` expression that is only semantically allowed in the condition
1358 /// of `if` / `while` expressions. (e.g., `if let 0 = x { .. }`).
1360 /// `Span` represents the whole `let pat = expr` statement.
1361 Let(P<Pat>, P<Expr>, Span),
1362 /// An `if` block, with an optional `else` block.
1364 /// `if expr { block } else { expr }`
1365 If(P<Expr>, P<Block>, Option<P<Expr>>),
1366 /// A while loop, with an optional label.
1368 /// `'label: while expr { block }`
1369 While(P<Expr>, P<Block>, Option<Label>),
1370 /// A `for` loop, with an optional label.
1372 /// `'label: for pat in expr { block }`
1374 /// This is desugared to a combination of `loop` and `match` expressions.
1375 ForLoop(P<Pat>, P<Expr>, P<Block>, Option<Label>),
1376 /// Conditionless loop (can be exited with `break`, `continue`, or `return`).
1378 /// `'label: loop { block }`
1379 Loop(P<Block>, Option<Label>, Span),
1380 /// A `match` block.
1381 Match(P<Expr>, Vec<Arm>),
1382 /// A closure (e.g., `move |a, b, c| a + b + c`).
1383 Closure(Box<Closure>),
1384 /// A block (`'label: { ... }`).
1385 Block(P<Block>, Option<Label>),
1386 /// An async block (`async move { ... }`).
1388 /// The `NodeId` is the `NodeId` for the closure that results from
1389 /// desugaring an async block, just like the NodeId field in the
1390 /// `Async::Yes` variant. This is necessary in order to create a def for the
1391 /// closure which can be used as a parent of any child defs. Defs
1392 /// created during lowering cannot be made the parent of any other
1393 /// preexisting defs.
1394 Async(CaptureBy, NodeId, P<Block>),
1395 /// An await expression (`my_future.await`).
1398 /// A try block (`try { ... }`).
1401 /// An assignment (`a = foo()`).
1402 /// The `Span` argument is the span of the `=` token.
1403 Assign(P<Expr>, P<Expr>, Span),
1404 /// An assignment with an operator.
1407 AssignOp(BinOp, P<Expr>, P<Expr>),
1408 /// Access of a named (e.g., `obj.foo`) or unnamed (e.g., `obj.0`) struct field.
1409 Field(P<Expr>, Ident),
1410 /// An indexing operation (e.g., `foo[2]`).
1411 Index(P<Expr>, P<Expr>),
1412 /// A range (e.g., `1..2`, `1..`, `..2`, `1..=2`, `..=2`; and `..` in destructuring assignment).
1413 Range(Option<P<Expr>>, Option<P<Expr>>, RangeLimits),
1414 /// An underscore, used in destructuring assignment to ignore a value.
1417 /// Variable reference, possibly containing `::` and/or type
1418 /// parameters (e.g., `foo::bar::<baz>`).
1420 /// Optionally "qualified" (e.g., `<Vec<T> as SomeTrait>::SomeType`).
1421 Path(Option<P<QSelf>>, Path),
1423 /// A referencing operation (`&a`, `&mut a`, `&raw const a` or `&raw mut a`).
1424 AddrOf(BorrowKind, Mutability, P<Expr>),
1425 /// A `break`, with an optional label to break, and an optional expression.
1426 Break(Option<Label>, Option<P<Expr>>),
1427 /// A `continue`, with an optional label.
1428 Continue(Option<Label>),
1429 /// A `return`, with an optional value to be returned.
1430 Ret(Option<P<Expr>>),
1432 /// Output of the `asm!()` macro.
1433 InlineAsm(P<InlineAsm>),
1435 /// A macro invocation; pre-expansion.
1436 MacCall(P<MacCall>),
1438 /// A struct literal expression.
1440 /// E.g., `Foo {x: 1, y: 2}`, or `Foo {x: 1, .. rest}`.
1441 Struct(P<StructExpr>),
1443 /// An array literal constructed from one repeated element.
1445 /// E.g., `[1; 5]`. The expression is the element to be
1446 /// repeated; the constant is the number of times to repeat it.
1447 Repeat(P<Expr>, AnonConst),
1449 /// No-op: used solely so we can pretty-print faithfully.
1452 /// A try expression (`expr?`).
1455 /// A `yield`, with an optional value to be yielded.
1456 Yield(Option<P<Expr>>),
1458 /// A `do yeet` (aka `throw`/`fail`/`bail`/`raise`/whatever),
1459 /// with an optional value to be returned.
1460 Yeet(Option<P<Expr>>),
1462 /// Bytes included via `include_bytes!`
1463 /// Added for optimization purposes to avoid the need to escape
1464 /// large binary blobs - should always behave like [`ExprKind::Lit`]
1465 /// with a `ByteStr` literal.
1466 IncludedBytes(Lrc<[u8]>),
1468 /// Placeholder for an expression that wasn't syntactically well formed in some way.
1472 /// The explicit `Self` type in a "qualified path". The actual
1473 /// path, including the trait and the associated item, is stored
1474 /// separately. `position` represents the index of the associated
1475 /// item qualified with this `Self` type.
1477 /// ```ignore (only-for-syntax-highlight)
1478 /// <Vec<T> as a::b::Trait>::AssociatedItem
1479 /// ^~~~~ ~~~~~~~~~~~~~~^
1482 /// <Vec<T>>::AssociatedItem
1486 #[derive(Clone, Encodable, Decodable, Debug)]
1490 /// The span of `a::b::Trait` in a path like `<Vec<T> as
1491 /// a::b::Trait>::AssociatedItem`; in the case where `position ==
1492 /// 0`, this is an empty span.
1493 pub path_span: Span,
1494 pub position: usize,
1497 /// A capture clause used in closures and `async` blocks.
1498 #[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
1499 pub enum CaptureBy {
1500 /// `move |x| y + x`.
1502 /// `move` keyword was not specified.
1506 /// The movability of a generator / closure literal:
1507 /// whether a generator contains self-references, causing it to be `!Unpin`.
1508 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable, Debug, Copy)]
1509 #[derive(HashStable_Generic)]
1510 pub enum Movability {
1511 /// May contain self-references, `!Unpin`.
1513 /// Must not contain self-references, `Unpin`.
1517 /// Closure lifetime binder, `for<'a, 'b>` in `for<'a, 'b> |_: &'a (), _: &'b ()|`.
1518 #[derive(Clone, Encodable, Decodable, Debug)]
1519 pub enum ClosureBinder {
1520 /// The binder is not present, all closure lifetimes are inferred.
1522 /// The binder is present.
1524 /// Span of the whole `for<>` clause
1527 /// for<'a, 'b> |_: &'a (), _: &'b ()| { ... }
1528 /// ^^^^^^^^^^^ -- this
1532 /// Lifetimes in the `for<>` closure
1535 /// for<'a, 'b> |_: &'a (), _: &'b ()| { ... }
1538 generic_params: P<[GenericParam]>,
1542 /// Represents a macro invocation. The `path` indicates which macro
1543 /// is being invoked, and the `args` are arguments passed to it.
1544 #[derive(Clone, Encodable, Decodable, Debug)]
1545 pub struct MacCall {
1547 pub args: P<DelimArgs>,
1548 pub prior_type_ascription: Option<(Span, bool)>,
1552 pub fn span(&self) -> Span {
1553 self.path.span.to(self.args.dspan.entire())
1557 /// Arguments passed to an attribute macro.
1558 #[derive(Clone, Encodable, Decodable, Debug)]
1560 /// No arguments: `#[attr]`.
1562 /// Delimited arguments: `#[attr()/[]/{}]`.
1563 Delimited(DelimArgs),
1564 /// Arguments of a key-value attribute: `#[attr = "value"]`.
1566 /// Span of the `=` token.
1573 // The RHS of an `AttrArgs::Eq` starts out as an expression. Once macro
1574 // expansion is completed, all cases end up either as a literal, which is the
1575 // form used after lowering to HIR, or as an error.
1576 #[derive(Clone, Encodable, Decodable, Debug)]
1577 pub enum AttrArgsEq {
1583 pub fn span(&self) -> Option<Span> {
1585 AttrArgs::Empty => None,
1586 AttrArgs::Delimited(args) => Some(args.dspan.entire()),
1587 AttrArgs::Eq(eq_span, AttrArgsEq::Ast(expr)) => Some(eq_span.to(expr.span)),
1588 AttrArgs::Eq(_, AttrArgsEq::Hir(lit)) => {
1589 unreachable!("in literal form when getting span: {:?}", lit);
1594 /// Tokens inside the delimiters or after `=`.
1595 /// Proc macros see these tokens, for example.
1596 pub fn inner_tokens(&self) -> TokenStream {
1598 AttrArgs::Empty => TokenStream::default(),
1599 AttrArgs::Delimited(args) => args.tokens.clone(),
1600 AttrArgs::Eq(_, AttrArgsEq::Ast(expr)) => TokenStream::from_ast(expr),
1601 AttrArgs::Eq(_, AttrArgsEq::Hir(lit)) => {
1602 unreachable!("in literal form when getting inner tokens: {:?}", lit)
1608 impl<CTX> HashStable<CTX> for AttrArgs
1610 CTX: crate::HashStableContext,
1612 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1613 mem::discriminant(self).hash_stable(ctx, hasher);
1615 AttrArgs::Empty => {}
1616 AttrArgs::Delimited(args) => args.hash_stable(ctx, hasher),
1617 AttrArgs::Eq(_eq_span, AttrArgsEq::Ast(expr)) => {
1618 unreachable!("hash_stable {:?}", expr);
1620 AttrArgs::Eq(eq_span, AttrArgsEq::Hir(lit)) => {
1621 eq_span.hash_stable(ctx, hasher);
1622 lit.hash_stable(ctx, hasher);
1628 /// Delimited arguments, as used in `#[attr()/[]/{}]` or `mac!()/[]/{}`.
1629 #[derive(Clone, Encodable, Decodable, Debug)]
1630 pub struct DelimArgs {
1631 pub dspan: DelimSpan,
1632 pub delim: MacDelimiter,
1633 pub tokens: TokenStream,
1637 /// Whether a macro with these arguments needs a semicolon
1638 /// when used as a standalone item or statement.
1639 pub fn need_semicolon(&self) -> bool {
1640 !matches!(self, DelimArgs { delim: MacDelimiter::Brace, .. })
1644 impl<CTX> HashStable<CTX> for DelimArgs
1646 CTX: crate::HashStableContext,
1648 fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
1649 let DelimArgs { dspan, delim, tokens } = self;
1650 dspan.hash_stable(ctx, hasher);
1651 delim.hash_stable(ctx, hasher);
1652 tokens.hash_stable(ctx, hasher);
1656 #[derive(Copy, Clone, PartialEq, Eq, Encodable, Decodable, Debug, HashStable_Generic)]
1657 pub enum MacDelimiter {
1664 pub fn to_token(self) -> Delimiter {
1666 MacDelimiter::Parenthesis => Delimiter::Parenthesis,
1667 MacDelimiter::Bracket => Delimiter::Bracket,
1668 MacDelimiter::Brace => Delimiter::Brace,
1672 pub fn from_token(delim: Delimiter) -> Option<MacDelimiter> {
1674 Delimiter::Parenthesis => Some(MacDelimiter::Parenthesis),
1675 Delimiter::Bracket => Some(MacDelimiter::Bracket),
1676 Delimiter::Brace => Some(MacDelimiter::Brace),
1677 Delimiter::Invisible => None,
1682 /// Represents a macro definition.
1683 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
1684 pub struct MacroDef {
1685 pub body: P<DelimArgs>,
1686 /// `true` if macro was defined with `macro_rules`.
1687 pub macro_rules: bool,
1690 #[derive(Clone, Encodable, Decodable, Debug, Copy, Hash, Eq, PartialEq)]
1691 #[derive(HashStable_Generic)]
1693 /// A regular string, like `"foo"`.
1695 /// A raw string, like `r##"foo"##`.
1697 /// The value is the number of `#` symbols used.
1702 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
1704 /// The original literal token as written in source code.
1705 pub token_lit: token::Lit,
1706 /// The "semantic" representation of the literal lowered from the original tokens.
1707 /// Strings are unescaped, hexadecimal forms are eliminated, etc.
1708 /// FIXME: Remove this and only create the semantic representation during lowering to HIR.
1713 /// Same as `Lit`, but restricted to string literals.
1714 #[derive(Clone, Copy, Encodable, Decodable, Debug)]
1716 /// The original literal token as written in source code.
1717 pub style: StrStyle,
1719 pub suffix: Option<Symbol>,
1721 /// The unescaped "semantic" representation of the literal lowered from the original token.
1722 /// FIXME: Remove this and only create the semantic representation during lowering to HIR.
1723 pub symbol_unescaped: Symbol,
1727 pub fn as_token_lit(&self) -> token::Lit {
1728 let token_kind = match self.style {
1729 StrStyle::Cooked => token::Str,
1730 StrStyle::Raw(n) => token::StrRaw(n),
1732 token::Lit::new(token_kind, self.symbol, self.suffix)
1736 /// Type of the integer literal based on provided suffix.
1737 #[derive(Clone, Copy, Encodable, Decodable, Debug, Hash, Eq, PartialEq)]
1738 #[derive(HashStable_Generic)]
1739 pub enum LitIntType {
1748 /// Type of the float literal based on provided suffix.
1749 #[derive(Clone, Copy, Encodable, Decodable, Debug, Hash, Eq, PartialEq)]
1750 #[derive(HashStable_Generic)]
1751 pub enum LitFloatType {
1752 /// A float literal with a suffix (`1f32` or `1E10f32`).
1754 /// A float literal without a suffix (`1.0 or 1.0E10`).
1758 /// Note that the entire literal (including the suffix) is considered when
1759 /// deciding the `LitKind`. This means that float literals like `1f32` are
1760 /// classified by this type as `Float`. This is different to `token::LitKind`
1761 /// which does *not* consider the suffix.
1762 #[derive(Clone, Encodable, Decodable, Debug, Hash, Eq, PartialEq, HashStable_Generic)]
1764 /// A string literal (`"foo"`). The symbol is unescaped, and so may differ
1765 /// from the original token's symbol.
1766 Str(Symbol, StrStyle),
1767 /// A byte string (`b"foo"`).
1769 /// A byte char (`b'f'`).
1771 /// A character literal (`'a'`).
1773 /// An integer literal (`1`).
1774 Int(u128, LitIntType),
1775 /// A float literal (`1.0`, `1f64` or `1E10f64`). The pre-suffix part is
1776 /// stored as a symbol rather than `f64` so that `LitKind` can impl `Eq`
1778 Float(Symbol, LitFloatType),
1779 /// A boolean literal (`true`, `false`).
1781 /// Placeholder for a literal that wasn't well-formed in some way.
1786 /// Returns `true` if this literal is a string.
1787 pub fn is_str(&self) -> bool {
1788 matches!(self, LitKind::Str(..))
1791 /// Returns `true` if this literal is byte literal string.
1792 pub fn is_bytestr(&self) -> bool {
1793 matches!(self, LitKind::ByteStr(_))
1796 /// Returns `true` if this is a numeric literal.
1797 pub fn is_numeric(&self) -> bool {
1798 matches!(self, LitKind::Int(..) | LitKind::Float(..))
1801 /// Returns `true` if this literal has no suffix.
1802 /// Note: this will return true for literals with prefixes such as raw strings and byte strings.
1803 pub fn is_unsuffixed(&self) -> bool {
1807 /// Returns `true` if this literal has a suffix.
1808 pub fn is_suffixed(&self) -> bool {
1810 // suffixed variants
1811 LitKind::Int(_, LitIntType::Signed(..) | LitIntType::Unsigned(..))
1812 | LitKind::Float(_, LitFloatType::Suffixed(..)) => true,
1813 // unsuffixed variants
1815 | LitKind::ByteStr(..)
1818 | LitKind::Int(_, LitIntType::Unsuffixed)
1819 | LitKind::Float(_, LitFloatType::Unsuffixed)
1821 | LitKind::Err => false,
1826 // N.B., If you change this, you'll probably want to change the corresponding
1827 // type structure in `middle/ty.rs` as well.
1828 #[derive(Clone, Encodable, Decodable, Debug)]
1831 pub mutbl: Mutability,
1834 /// Represents a function's signature in a trait declaration,
1835 /// trait implementation, or free function.
1836 #[derive(Clone, Encodable, Decodable, Debug)]
1838 pub header: FnHeader,
1839 pub decl: P<FnDecl>,
1843 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
1844 #[derive(Encodable, Decodable, HashStable_Generic)]
1851 pub fn name_str(self) -> &'static str {
1853 FloatTy::F32 => "f32",
1854 FloatTy::F64 => "f64",
1858 pub fn name(self) -> Symbol {
1860 FloatTy::F32 => sym::f32,
1861 FloatTy::F64 => sym::f64,
1866 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
1867 #[derive(Encodable, Decodable, HashStable_Generic)]
1878 pub fn name_str(&self) -> &'static str {
1880 IntTy::Isize => "isize",
1882 IntTy::I16 => "i16",
1883 IntTy::I32 => "i32",
1884 IntTy::I64 => "i64",
1885 IntTy::I128 => "i128",
1889 pub fn name(&self) -> Symbol {
1891 IntTy::Isize => sym::isize,
1892 IntTy::I8 => sym::i8,
1893 IntTy::I16 => sym::i16,
1894 IntTy::I32 => sym::i32,
1895 IntTy::I64 => sym::i64,
1896 IntTy::I128 => sym::i128,
1901 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Copy, Debug)]
1902 #[derive(Encodable, Decodable, HashStable_Generic)]
1913 pub fn name_str(&self) -> &'static str {
1915 UintTy::Usize => "usize",
1917 UintTy::U16 => "u16",
1918 UintTy::U32 => "u32",
1919 UintTy::U64 => "u64",
1920 UintTy::U128 => "u128",
1924 pub fn name(&self) -> Symbol {
1926 UintTy::Usize => sym::usize,
1927 UintTy::U8 => sym::u8,
1928 UintTy::U16 => sym::u16,
1929 UintTy::U32 => sym::u32,
1930 UintTy::U64 => sym::u64,
1931 UintTy::U128 => sym::u128,
1936 /// A constraint on an associated type (e.g., `A = Bar` in `Foo<A = Bar>` or
1937 /// `A: TraitA + TraitB` in `Foo<A: TraitA + TraitB>`).
1938 #[derive(Clone, Encodable, Decodable, Debug)]
1939 pub struct AssocConstraint {
1942 pub gen_args: Option<GenericArgs>,
1943 pub kind: AssocConstraintKind,
1947 /// The kinds of an `AssocConstraint`.
1948 #[derive(Clone, Encodable, Decodable, Debug)]
1954 impl From<P<Ty>> for Term {
1955 fn from(v: P<Ty>) -> Self {
1960 impl From<AnonConst> for Term {
1961 fn from(v: AnonConst) -> Self {
1966 /// The kinds of an `AssocConstraint`.
1967 #[derive(Clone, Encodable, Decodable, Debug)]
1968 pub enum AssocConstraintKind {
1969 /// E.g., `A = Bar`, `A = 3` in `Foo<A = Bar>` where A is an associated type.
1970 Equality { term: Term },
1971 /// E.g. `A: TraitA + TraitB` in `Foo<A: TraitA + TraitB>`.
1972 Bound { bounds: GenericBounds },
1975 #[derive(Encodable, Decodable, Debug)]
1980 pub tokens: Option<LazyAttrTokenStream>,
1984 fn clone(&self) -> Self {
1985 ensure_sufficient_stack(|| Self {
1987 kind: self.kind.clone(),
1989 tokens: self.tokens.clone(),
1995 pub fn peel_refs(&self) -> &Self {
1996 let mut final_ty = self;
1997 while let TyKind::Rptr(_, MutTy { ty, .. }) = &final_ty.kind {
2004 #[derive(Clone, Encodable, Decodable, Debug)]
2005 pub struct BareFnTy {
2006 pub unsafety: Unsafe,
2008 pub generic_params: Vec<GenericParam>,
2009 pub decl: P<FnDecl>,
2010 /// Span of the `fn(...) -> ...` part.
2011 pub decl_span: Span,
2014 /// The various kinds of type recognized by the compiler.
2015 #[derive(Clone, Encodable, Decodable, Debug)]
2017 /// A variable-length slice (`[T]`).
2019 /// A fixed length array (`[T; n]`).
2020 Array(P<Ty>, AnonConst),
2021 /// A raw pointer (`*const T` or `*mut T`).
2023 /// A reference (`&'a T` or `&'a mut T`).
2024 Rptr(Option<Lifetime>, MutTy),
2025 /// A bare function (e.g., `fn(usize) -> bool`).
2026 BareFn(P<BareFnTy>),
2027 /// The never type (`!`).
2029 /// A tuple (`(A, B, C, D,...)`).
2031 /// A path (`module::module::...::Type`), optionally
2032 /// "qualified", e.g., `<Vec<T> as SomeTrait>::SomeType`.
2034 /// Type parameters are stored in the `Path` itself.
2035 Path(Option<P<QSelf>>, Path),
2036 /// A trait object type `Bound1 + Bound2 + Bound3`
2037 /// where `Bound` is a trait or a lifetime.
2038 TraitObject(GenericBounds, TraitObjectSyntax),
2039 /// An `impl Bound1 + Bound2 + Bound3` type
2040 /// where `Bound` is a trait or a lifetime.
2042 /// The `NodeId` exists to prevent lowering from having to
2043 /// generate `NodeId`s on the fly, which would complicate
2044 /// the generation of opaque `type Foo = impl Trait` items significantly.
2045 ImplTrait(NodeId, GenericBounds),
2046 /// No-op; kept solely so that we can pretty-print faithfully.
2050 /// This means the type should be inferred instead of it having been
2051 /// specified. This can appear anywhere in a type.
2053 /// Inferred type of a `self` or `&self` argument in a method.
2055 /// A macro in the type position.
2056 MacCall(P<MacCall>),
2057 /// Placeholder for a kind that has failed to be defined.
2059 /// Placeholder for a `va_list`.
2064 pub fn is_implicit_self(&self) -> bool {
2065 matches!(self, TyKind::ImplicitSelf)
2068 pub fn is_unit(&self) -> bool {
2069 matches!(self, TyKind::Tup(tys) if tys.is_empty())
2072 pub fn is_simple_path(&self) -> Option<Symbol> {
2073 if let TyKind::Path(None, Path { segments, .. }) = &self
2074 && let [segment] = &segments[..]
2075 && segment.args.is_none()
2077 Some(segment.ident.name)
2084 /// Syntax used to declare a trait object.
2085 #[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
2086 pub enum TraitObjectSyntax {
2092 /// Inline assembly operand explicit register or register class.
2094 /// E.g., `"eax"` as in `asm!("mov eax, 2", out("eax") result)`.
2095 #[derive(Clone, Copy, Encodable, Decodable, Debug)]
2096 pub enum InlineAsmRegOrRegClass {
2101 bitflags::bitflags! {
2102 #[derive(Encodable, Decodable, HashStable_Generic)]
2103 pub struct InlineAsmOptions: u16 {
2104 const PURE = 1 << 0;
2105 const NOMEM = 1 << 1;
2106 const READONLY = 1 << 2;
2107 const PRESERVES_FLAGS = 1 << 3;
2108 const NORETURN = 1 << 4;
2109 const NOSTACK = 1 << 5;
2110 const ATT_SYNTAX = 1 << 6;
2112 const MAY_UNWIND = 1 << 8;
2116 #[derive(Clone, PartialEq, Encodable, Decodable, Debug, Hash, HashStable_Generic)]
2117 pub enum InlineAsmTemplatePiece {
2119 Placeholder { operand_idx: usize, modifier: Option<char>, span: Span },
2122 impl fmt::Display for InlineAsmTemplatePiece {
2123 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2125 Self::String(s) => {
2126 for c in s.chars() {
2128 '{' => f.write_str("{{")?,
2129 '}' => f.write_str("}}")?,
2135 Self::Placeholder { operand_idx, modifier: Some(modifier), .. } => {
2136 write!(f, "{{{}:{}}}", operand_idx, modifier)
2138 Self::Placeholder { operand_idx, modifier: None, .. } => {
2139 write!(f, "{{{}}}", operand_idx)
2145 impl InlineAsmTemplatePiece {
2146 /// Rebuilds the asm template string from its pieces.
2147 pub fn to_string(s: &[Self]) -> String {
2149 let mut out = String::new();
2151 let _ = write!(out, "{}", p);
2157 /// Inline assembly symbol operands get their own AST node that is somewhat
2158 /// similar to `AnonConst`.
2160 /// The main difference is that we specifically don't assign it `DefId` in
2161 /// `DefCollector`. Instead this is deferred until AST lowering where we
2162 /// lower it to an `AnonConst` (for functions) or a `Path` (for statics)
2163 /// depending on what the path resolves to.
2164 #[derive(Clone, Encodable, Decodable, Debug)]
2165 pub struct InlineAsmSym {
2167 pub qself: Option<P<QSelf>>,
2171 /// Inline assembly operand.
2173 /// E.g., `out("eax") result` as in `asm!("mov eax, 2", out("eax") result)`.
2174 #[derive(Clone, Encodable, Decodable, Debug)]
2175 pub enum InlineAsmOperand {
2177 reg: InlineAsmRegOrRegClass,
2181 reg: InlineAsmRegOrRegClass,
2183 expr: Option<P<Expr>>,
2186 reg: InlineAsmRegOrRegClass,
2191 reg: InlineAsmRegOrRegClass,
2194 out_expr: Option<P<Expr>>,
2197 anon_const: AnonConst,
2204 /// Inline assembly.
2206 /// E.g., `asm!("NOP");`.
2207 #[derive(Clone, Encodable, Decodable, Debug)]
2208 pub struct InlineAsm {
2209 pub template: Vec<InlineAsmTemplatePiece>,
2210 pub template_strs: Box<[(Symbol, Option<Symbol>, Span)]>,
2211 pub operands: Vec<(InlineAsmOperand, Span)>,
2212 pub clobber_abis: Vec<(Symbol, Span)>,
2213 pub options: InlineAsmOptions,
2214 pub line_spans: Vec<Span>,
2217 /// A parameter in a function header.
2219 /// E.g., `bar: usize` as in `fn foo(bar: usize)`.
2220 #[derive(Clone, Encodable, Decodable, Debug)]
2227 pub is_placeholder: bool,
2230 /// Alternative representation for `Arg`s describing `self` parameter of methods.
2232 /// E.g., `&mut self` as in `fn foo(&mut self)`.
2233 #[derive(Clone, Encodable, Decodable, Debug)]
2235 /// `self`, `mut self`
2237 /// `&'lt self`, `&'lt mut self`
2238 Region(Option<Lifetime>, Mutability),
2239 /// `self: TYPE`, `mut self: TYPE`
2240 Explicit(P<Ty>, Mutability),
2243 pub type ExplicitSelf = Spanned<SelfKind>;
2246 /// Attempts to cast parameter to `ExplicitSelf`.
2247 pub fn to_self(&self) -> Option<ExplicitSelf> {
2248 if let PatKind::Ident(BindingAnnotation(ByRef::No, mutbl), ident, _) = self.pat.kind {
2249 if ident.name == kw::SelfLower {
2250 return match self.ty.kind {
2251 TyKind::ImplicitSelf => Some(respan(self.pat.span, SelfKind::Value(mutbl))),
2252 TyKind::Rptr(lt, MutTy { ref ty, mutbl }) if ty.kind.is_implicit_self() => {
2253 Some(respan(self.pat.span, SelfKind::Region(lt, mutbl)))
2256 self.pat.span.to(self.ty.span),
2257 SelfKind::Explicit(self.ty.clone(), mutbl),
2265 /// Returns `true` if parameter is `self`.
2266 pub fn is_self(&self) -> bool {
2267 if let PatKind::Ident(_, ident, _) = self.pat.kind {
2268 ident.name == kw::SelfLower
2274 /// Builds a `Param` object from `ExplicitSelf`.
2275 pub fn from_self(attrs: AttrVec, eself: ExplicitSelf, eself_ident: Ident) -> Param {
2276 let span = eself.span.to(eself_ident.span);
2277 let infer_ty = P(Ty { id: DUMMY_NODE_ID, kind: TyKind::ImplicitSelf, span, tokens: None });
2278 let (mutbl, ty) = match eself.node {
2279 SelfKind::Explicit(ty, mutbl) => (mutbl, ty),
2280 SelfKind::Value(mutbl) => (mutbl, infer_ty),
2281 SelfKind::Region(lt, mutbl) => (
2285 kind: TyKind::Rptr(lt, MutTy { ty: infer_ty, mutbl }),
2295 kind: PatKind::Ident(BindingAnnotation(ByRef::No, mutbl), eself_ident, None),
2302 is_placeholder: false,
2307 /// A signature (not the body) of a function declaration.
2309 /// E.g., `fn foo(bar: baz)`.
2311 /// Please note that it's different from `FnHeader` structure
2312 /// which contains metadata about function safety, asyncness, constness and ABI.
2313 #[derive(Clone, Encodable, Decodable, Debug)]
2315 pub inputs: Vec<Param>,
2316 pub output: FnRetTy,
2320 pub fn has_self(&self) -> bool {
2321 self.inputs.get(0).map_or(false, Param::is_self)
2323 pub fn c_variadic(&self) -> bool {
2324 self.inputs.last().map_or(false, |arg| matches!(arg.ty.kind, TyKind::CVarArgs))
2328 /// Is the trait definition an auto trait?
2329 #[derive(Copy, Clone, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
2335 #[derive(Copy, Clone, PartialEq, Eq, Hash, Encodable, Decodable, Debug)]
2336 #[derive(HashStable_Generic)]
2342 #[derive(Copy, Clone, Encodable, Decodable, Debug)]
2344 Yes { span: Span, closure_id: NodeId, return_impl_trait_id: NodeId },
2349 pub fn is_async(self) -> bool {
2350 matches!(self, Async::Yes { .. })
2353 /// In this case this is an `async` return, the `NodeId` for the generated `impl Trait` item.
2354 pub fn opt_return_id(self) -> Option<(NodeId, Span)> {
2356 Async::Yes { return_impl_trait_id, span, .. } => Some((return_impl_trait_id, span)),
2362 #[derive(Copy, Clone, PartialEq, Eq, Hash, Encodable, Decodable, Debug)]
2363 #[derive(HashStable_Generic)]
2369 /// Item defaultness.
2370 /// For details see the [RFC #2532](https://github.com/rust-lang/rfcs/pull/2532).
2371 #[derive(Copy, Clone, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
2372 pub enum Defaultness {
2377 #[derive(Copy, Clone, PartialEq, Encodable, Decodable, HashStable_Generic)]
2378 pub enum ImplPolarity {
2379 /// `impl Trait for Type`
2381 /// `impl !Trait for Type`
2385 impl fmt::Debug for ImplPolarity {
2386 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2388 ImplPolarity::Positive => "positive".fmt(f),
2389 ImplPolarity::Negative(_) => "negative".fmt(f),
2394 #[derive(Clone, Encodable, Decodable, Debug)]
2396 /// Returns type is not specified.
2398 /// Functions default to `()` and closures default to inference.
2399 /// Span points to where return type would be inserted.
2401 /// Everything else.
2406 pub fn span(&self) -> Span {
2408 &FnRetTy::Default(span) => span,
2409 FnRetTy::Ty(ty) => ty.span,
2414 #[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug)]
2420 /// Module item kind.
2421 #[derive(Clone, Encodable, Decodable, Debug)]
2423 /// Module with inlined definition `mod foo { ... }`,
2424 /// or with definition outlined to a separate file `mod foo;` and already loaded from it.
2425 /// The inner span is from the first token past `{` to the last token until `}`,
2426 /// or from the first to the last token in the loaded file.
2427 Loaded(Vec<P<Item>>, Inline, ModSpans),
2428 /// Module with definition outlined to a separate file `mod foo;` but not yet loaded from it.
2432 #[derive(Copy, Clone, Encodable, Decodable, Debug)]
2433 pub struct ModSpans {
2434 /// `inner_span` covers the body of the module; for a file module, its the whole file.
2435 /// For an inline module, its the span inside the `{ ... }`, not including the curly braces.
2436 pub inner_span: Span,
2437 pub inject_use_span: Span,
2440 impl Default for ModSpans {
2441 fn default() -> ModSpans {
2442 ModSpans { inner_span: Default::default(), inject_use_span: Default::default() }
2446 /// Foreign module declaration.
2448 /// E.g., `extern { .. }` or `extern "C" { .. }`.
2449 #[derive(Clone, Encodable, Decodable, Debug)]
2450 pub struct ForeignMod {
2451 /// `unsafe` keyword accepted syntactically for macro DSLs, but not
2452 /// semantically by Rust.
2453 pub unsafety: Unsafe,
2454 pub abi: Option<StrLit>,
2455 pub items: Vec<P<ForeignItem>>,
2458 #[derive(Clone, Encodable, Decodable, Debug)]
2459 pub struct EnumDef {
2460 pub variants: Vec<Variant>,
2463 #[derive(Clone, Encodable, Decodable, Debug)]
2464 pub struct Variant {
2465 /// Attributes of the variant.
2467 /// Id of the variant (not the constructor, see `VariantData::ctor_id()`).
2471 /// The visibility of the variant. Syntactically accepted but not semantically.
2472 pub vis: Visibility,
2473 /// Name of the variant.
2476 /// Fields and constructor id of the variant.
2477 pub data: VariantData,
2478 /// Explicit discriminant, e.g., `Foo = 1`.
2479 pub disr_expr: Option<AnonConst>,
2480 /// Is a macro placeholder
2481 pub is_placeholder: bool,
2484 /// Part of `use` item to the right of its prefix.
2485 #[derive(Clone, Encodable, Decodable, Debug)]
2486 pub enum UseTreeKind {
2487 /// `use prefix` or `use prefix as rename`
2489 /// The extra `NodeId`s are for HIR lowering, when additional statements are created for each
2491 Simple(Option<Ident>, NodeId, NodeId),
2492 /// `use prefix::{...}`
2493 Nested(Vec<(UseTree, NodeId)>),
2498 /// A tree of paths sharing common prefixes.
2499 /// Used in `use` items both at top-level and inside of braces in import groups.
2500 #[derive(Clone, Encodable, Decodable, Debug)]
2501 pub struct UseTree {
2503 pub kind: UseTreeKind,
2508 pub fn ident(&self) -> Ident {
2510 UseTreeKind::Simple(Some(rename), ..) => rename,
2511 UseTreeKind::Simple(None, ..) => {
2512 self.prefix.segments.last().expect("empty prefix in a simple import").ident
2514 _ => panic!("`UseTree::ident` can only be used on a simple import"),
2519 /// Distinguishes between `Attribute`s that decorate items and Attributes that
2520 /// are contained as statements within items. These two cases need to be
2521 /// distinguished for pretty-printing.
2522 #[derive(Clone, PartialEq, Encodable, Decodable, Debug, Copy, HashStable_Generic)]
2523 pub enum AttrStyle {
2528 rustc_index::newtype_index! {
2531 DEBUG_FORMAT = "AttrId({})"
2535 impl<S: Encoder> Encodable<S> for AttrId {
2536 fn encode(&self, _s: &mut S) {}
2539 impl<D: Decoder> Decodable<D> for AttrId {
2540 default fn decode(_: &mut D) -> AttrId {
2541 panic!("cannot decode `AttrId` with `{}`", std::any::type_name::<D>());
2545 #[derive(Clone, Encodable, Decodable, Debug, HashStable_Generic)]
2546 pub struct AttrItem {
2549 pub tokens: Option<LazyAttrTokenStream>,
2552 /// A list of attributes.
2553 pub type AttrVec = ThinVec<Attribute>;
2555 /// Metadata associated with an item.
2556 #[derive(Clone, Encodable, Decodable, Debug)]
2557 pub struct Attribute {
2560 /// Denotes if the attribute decorates the following construct (outer)
2561 /// or the construct this attribute is contained within (inner).
2562 pub style: AttrStyle,
2566 #[derive(Clone, Encodable, Decodable, Debug)]
2567 pub struct NormalAttr {
2569 pub tokens: Option<LazyAttrTokenStream>,
2572 #[derive(Clone, Encodable, Decodable, Debug)]
2574 /// A normal attribute.
2575 Normal(P<NormalAttr>),
2577 /// A doc comment (e.g. `/// ...`, `//! ...`, `/** ... */`, `/*! ... */`).
2578 /// Doc attributes (e.g. `#[doc="..."]`) are represented with the `Normal`
2579 /// variant (which is much less compact and thus more expensive).
2580 DocComment(CommentKind, Symbol),
2583 /// `TraitRef`s appear in impls.
2585 /// Resolution maps each `TraitRef`'s `ref_id` to its defining trait; that's all
2586 /// that the `ref_id` is for. The `impl_id` maps to the "self type" of this impl.
2587 /// If this impl is an `ItemKind::Impl`, the `impl_id` is redundant (it could be the
2588 /// same as the impl's `NodeId`).
2589 #[derive(Clone, Encodable, Decodable, Debug)]
2590 pub struct TraitRef {
2595 #[derive(Clone, Encodable, Decodable, Debug)]
2596 pub struct PolyTraitRef {
2597 /// The `'a` in `for<'a> Foo<&'a T>`.
2598 pub bound_generic_params: Vec<GenericParam>,
2600 /// The `Foo<&'a T>` in `<'a> Foo<&'a T>`.
2601 pub trait_ref: TraitRef,
2607 pub fn new(generic_params: Vec<GenericParam>, path: Path, span: Span) -> Self {
2609 bound_generic_params: generic_params,
2610 trait_ref: TraitRef { path, ref_id: DUMMY_NODE_ID },
2616 #[derive(Clone, Encodable, Decodable, Debug)]
2617 pub struct Visibility {
2618 pub kind: VisibilityKind,
2620 pub tokens: Option<LazyAttrTokenStream>,
2623 #[derive(Clone, Encodable, Decodable, Debug)]
2624 pub enum VisibilityKind {
2626 Restricted { path: P<Path>, id: NodeId, shorthand: bool },
2630 impl VisibilityKind {
2631 pub fn is_pub(&self) -> bool {
2632 matches!(self, VisibilityKind::Public)
2636 /// Field definition in a struct, variant or union.
2638 /// E.g., `bar: usize` as in `struct Foo { bar: usize }`.
2639 #[derive(Clone, Encodable, Decodable, Debug)]
2640 pub struct FieldDef {
2644 pub vis: Visibility,
2645 pub ident: Option<Ident>,
2648 pub is_placeholder: bool,
2651 /// Fields and constructor ids of enum variants and structs.
2652 #[derive(Clone, Encodable, Decodable, Debug)]
2653 pub enum VariantData {
2656 /// E.g., `Bar { .. }` as in `enum Foo { Bar { .. } }`.
2657 Struct(Vec<FieldDef>, bool),
2660 /// E.g., `Bar(..)` as in `enum Foo { Bar(..) }`.
2661 Tuple(Vec<FieldDef>, NodeId),
2664 /// E.g., `Bar = ..` as in `enum Foo { Bar = .. }`.
2669 /// Return the fields of this variant.
2670 pub fn fields(&self) -> &[FieldDef] {
2672 VariantData::Struct(fields, ..) | VariantData::Tuple(fields, _) => fields,
2677 /// Return the `NodeId` of this variant's constructor, if it has one.
2678 pub fn ctor_node_id(&self) -> Option<NodeId> {
2680 VariantData::Struct(..) => None,
2681 VariantData::Tuple(_, id) | VariantData::Unit(id) => Some(id),
2686 /// An item definition.
2687 #[derive(Clone, Encodable, Decodable, Debug)]
2688 pub struct Item<K = ItemKind> {
2692 pub vis: Visibility,
2693 /// The name of the item.
2694 /// It might be a dummy name in case of anonymous items.
2699 /// Original tokens this item was parsed from. This isn't necessarily
2700 /// available for all items, although over time more and more items should
2701 /// have this be `Some`. Right now this is primarily used for procedural
2702 /// macros, notably custom attributes.
2704 /// Note that the tokens here do not include the outer attributes, but will
2705 /// include inner attributes.
2706 pub tokens: Option<LazyAttrTokenStream>,
2710 /// Return the span that encompasses the attributes.
2711 pub fn span_with_attributes(&self) -> Span {
2712 self.attrs.iter().fold(self.span, |acc, attr| acc.to(attr.span))
2716 /// `extern` qualifier on a function item or function type.
2717 #[derive(Clone, Copy, Encodable, Decodable, Debug)]
2721 Explicit(StrLit, Span),
2725 pub fn from_abi(abi: Option<StrLit>, span: Span) -> Extern {
2727 Some(name) => Extern::Explicit(name, span),
2728 None => Extern::Implicit(span),
2733 /// A function header.
2735 /// All the information between the visibility and the name of the function is
2736 /// included in this struct (e.g., `async unsafe fn` or `const extern "C" fn`).
2737 #[derive(Clone, Copy, Encodable, Decodable, Debug)]
2738 pub struct FnHeader {
2739 pub unsafety: Unsafe,
2740 pub asyncness: Async,
2741 pub constness: Const,
2746 /// Does this function header have any qualifiers or is it empty?
2747 pub fn has_qualifiers(&self) -> bool {
2748 let Self { unsafety, asyncness, constness, ext } = self;
2749 matches!(unsafety, Unsafe::Yes(_))
2750 || asyncness.is_async()
2751 || matches!(constness, Const::Yes(_))
2752 || !matches!(ext, Extern::None)
2756 impl Default for FnHeader {
2757 fn default() -> FnHeader {
2759 unsafety: Unsafe::No,
2760 asyncness: Async::No,
2761 constness: Const::No,
2767 #[derive(Clone, Encodable, Decodable, Debug)]
2769 pub unsafety: Unsafe,
2770 pub is_auto: IsAuto,
2771 pub generics: Generics,
2772 pub bounds: GenericBounds,
2773 pub items: Vec<P<AssocItem>>,
2776 /// The location of a where clause on a `TyAlias` (`Span`) and whether there was
2777 /// a `where` keyword (`bool`). This is split out from `WhereClause`, since there
2778 /// are two locations for where clause on type aliases, but their predicates
2779 /// are concatenated together.
2781 /// Take this example:
2782 /// ```ignore (only-for-syntax-highlight)
2784 /// type Assoc<'a, 'b> where Self: 'a, Self: 'b;
2786 /// impl Foo for () {
2787 /// type Assoc<'a, 'b> where Self: 'a = () where Self: 'b;
2788 /// // ^^^^^^^^^^^^^^ first where clause
2789 /// // ^^^^^^^^^^^^^^ second where clause
2793 /// If there is no where clause, then this is `false` with `DUMMY_SP`.
2794 #[derive(Copy, Clone, Encodable, Decodable, Debug, Default)]
2795 pub struct TyAliasWhereClause(pub bool, pub Span);
2797 #[derive(Clone, Encodable, Decodable, Debug)]
2798 pub struct TyAlias {
2799 pub defaultness: Defaultness,
2800 pub generics: Generics,
2801 /// The span information for the two where clauses (before equals, after equals)
2802 pub where_clauses: (TyAliasWhereClause, TyAliasWhereClause),
2803 /// The index in `generics.where_clause.predicates` that would split into
2804 /// predicates from the where clause before the equals and the predicates
2805 /// from the where clause after the equals
2806 pub where_predicates_split: usize,
2807 pub bounds: GenericBounds,
2808 pub ty: Option<P<Ty>>,
2811 #[derive(Clone, Encodable, Decodable, Debug)]
2813 pub defaultness: Defaultness,
2814 pub unsafety: Unsafe,
2815 pub generics: Generics,
2816 pub constness: Const,
2817 pub polarity: ImplPolarity,
2818 /// The trait being implemented, if any.
2819 pub of_trait: Option<TraitRef>,
2821 pub items: Vec<P<AssocItem>>,
2824 #[derive(Clone, Encodable, Decodable, Debug)]
2826 pub defaultness: Defaultness,
2827 pub generics: Generics,
2829 pub body: Option<P<Block>>,
2832 #[derive(Clone, Encodable, Decodable, Debug)]
2834 /// An `extern crate` item, with the optional *original* crate name if the crate was renamed.
2836 /// E.g., `extern crate foo` or `extern crate foo_bar as foo`.
2837 ExternCrate(Option<Symbol>),
2838 /// A use declaration item (`use`).
2840 /// E.g., `use foo;`, `use foo::bar;` or `use foo::bar as FooBar;`.
2842 /// A static item (`static`).
2844 /// E.g., `static FOO: i32 = 42;` or `static FOO: &'static str = "bar";`.
2845 Static(P<Ty>, Mutability, Option<P<Expr>>),
2846 /// A constant item (`const`).
2848 /// E.g., `const FOO: i32 = 42;`.
2849 Const(Defaultness, P<Ty>, Option<P<Expr>>),
2850 /// A function declaration (`fn`).
2852 /// E.g., `fn foo(bar: usize) -> usize { .. }`.
2854 /// A module declaration (`mod`).
2856 /// E.g., `mod foo;` or `mod foo { .. }`.
2857 /// `unsafe` keyword on modules is accepted syntactically for macro DSLs, but not
2858 /// semantically by Rust.
2859 Mod(Unsafe, ModKind),
2860 /// An external module (`extern`).
2862 /// E.g., `extern {}` or `extern "C" {}`.
2863 ForeignMod(ForeignMod),
2864 /// Module-level inline assembly (from `global_asm!()`).
2865 GlobalAsm(Box<InlineAsm>),
2866 /// A type alias (`type`).
2868 /// E.g., `type Foo = Bar<u8>;`.
2869 TyAlias(Box<TyAlias>),
2870 /// An enum definition (`enum`).
2872 /// E.g., `enum Foo<A, B> { C<A>, D<B> }`.
2873 Enum(EnumDef, Generics),
2874 /// A struct definition (`struct`).
2876 /// E.g., `struct Foo<A> { x: A }`.
2877 Struct(VariantData, Generics),
2878 /// A union definition (`union`).
2880 /// E.g., `union Foo<A, B> { x: A, y: B }`.
2881 Union(VariantData, Generics),
2882 /// A trait declaration (`trait`).
2884 /// E.g., `trait Foo { .. }`, `trait Foo<T> { .. }` or `auto trait Foo {}`.
2888 /// E.g., `trait Foo = Bar + Quux;`.
2889 TraitAlias(Generics, GenericBounds),
2890 /// An implementation.
2892 /// E.g., `impl<A> Foo<A> { .. }` or `impl<A> Trait for Foo<A> { .. }`.
2894 /// A macro invocation.
2896 /// E.g., `foo!(..)`.
2897 MacCall(P<MacCall>),
2899 /// A macro definition.
2904 pub fn article(&self) -> &str {
2907 Use(..) | Static(..) | Const(..) | Fn(..) | Mod(..) | GlobalAsm(..) | TyAlias(..)
2908 | Struct(..) | Union(..) | Trait(..) | TraitAlias(..) | MacroDef(..) => "a",
2909 ExternCrate(..) | ForeignMod(..) | MacCall(..) | Enum(..) | Impl { .. } => "an",
2913 pub fn descr(&self) -> &str {
2915 ItemKind::ExternCrate(..) => "extern crate",
2916 ItemKind::Use(..) => "`use` import",
2917 ItemKind::Static(..) => "static item",
2918 ItemKind::Const(..) => "constant item",
2919 ItemKind::Fn(..) => "function",
2920 ItemKind::Mod(..) => "module",
2921 ItemKind::ForeignMod(..) => "extern block",
2922 ItemKind::GlobalAsm(..) => "global asm item",
2923 ItemKind::TyAlias(..) => "type alias",
2924 ItemKind::Enum(..) => "enum",
2925 ItemKind::Struct(..) => "struct",
2926 ItemKind::Union(..) => "union",
2927 ItemKind::Trait(..) => "trait",
2928 ItemKind::TraitAlias(..) => "trait alias",
2929 ItemKind::MacCall(..) => "item macro invocation",
2930 ItemKind::MacroDef(..) => "macro definition",
2931 ItemKind::Impl { .. } => "implementation",
2935 pub fn generics(&self) -> Option<&Generics> {
2937 Self::Fn(box Fn { generics, .. })
2938 | Self::TyAlias(box TyAlias { generics, .. })
2939 | Self::Enum(_, generics)
2940 | Self::Struct(_, generics)
2941 | Self::Union(_, generics)
2942 | Self::Trait(box Trait { generics, .. })
2943 | Self::TraitAlias(generics, _)
2944 | Self::Impl(box Impl { generics, .. }) => Some(generics),
2950 /// Represents associated items.
2951 /// These include items in `impl` and `trait` definitions.
2952 pub type AssocItem = Item<AssocItemKind>;
2954 /// Represents associated item kinds.
2956 /// The term "provided" in the variants below refers to the item having a default
2957 /// definition / body. Meanwhile, a "required" item lacks a definition / body.
2958 /// In an implementation, all items must be provided.
2959 /// The `Option`s below denote the bodies, where `Some(_)`
2960 /// means "provided" and conversely `None` means "required".
2961 #[derive(Clone, Encodable, Decodable, Debug)]
2962 pub enum AssocItemKind {
2963 /// An associated constant, `const $ident: $ty $def?;` where `def ::= "=" $expr? ;`.
2964 /// If `def` is parsed, then the constant is provided, and otherwise required.
2965 Const(Defaultness, P<Ty>, Option<P<Expr>>),
2966 /// An associated function.
2968 /// An associated type.
2970 /// A macro expanding to associated items.
2971 MacCall(P<MacCall>),
2974 impl AssocItemKind {
2975 pub fn defaultness(&self) -> Defaultness {
2977 Self::Const(defaultness, ..)
2978 | Self::Fn(box Fn { defaultness, .. })
2979 | Self::Type(box TyAlias { defaultness, .. }) => defaultness,
2980 Self::MacCall(..) => Defaultness::Final,
2985 impl From<AssocItemKind> for ItemKind {
2986 fn from(assoc_item_kind: AssocItemKind) -> ItemKind {
2987 match assoc_item_kind {
2988 AssocItemKind::Const(a, b, c) => ItemKind::Const(a, b, c),
2989 AssocItemKind::Fn(fn_kind) => ItemKind::Fn(fn_kind),
2990 AssocItemKind::Type(ty_alias_kind) => ItemKind::TyAlias(ty_alias_kind),
2991 AssocItemKind::MacCall(a) => ItemKind::MacCall(a),
2996 impl TryFrom<ItemKind> for AssocItemKind {
2997 type Error = ItemKind;
2999 fn try_from(item_kind: ItemKind) -> Result<AssocItemKind, ItemKind> {
3000 Ok(match item_kind {
3001 ItemKind::Const(a, b, c) => AssocItemKind::Const(a, b, c),
3002 ItemKind::Fn(fn_kind) => AssocItemKind::Fn(fn_kind),
3003 ItemKind::TyAlias(ty_kind) => AssocItemKind::Type(ty_kind),
3004 ItemKind::MacCall(a) => AssocItemKind::MacCall(a),
3005 _ => return Err(item_kind),
3010 /// An item in `extern` block.
3011 #[derive(Clone, Encodable, Decodable, Debug)]
3012 pub enum ForeignItemKind {
3013 /// A foreign static item (`static FOO: u8`).
3014 Static(P<Ty>, Mutability, Option<P<Expr>>),
3015 /// An foreign function.
3017 /// An foreign type.
3018 TyAlias(Box<TyAlias>),
3019 /// A macro expanding to foreign items.
3020 MacCall(P<MacCall>),
3023 impl From<ForeignItemKind> for ItemKind {
3024 fn from(foreign_item_kind: ForeignItemKind) -> ItemKind {
3025 match foreign_item_kind {
3026 ForeignItemKind::Static(a, b, c) => ItemKind::Static(a, b, c),
3027 ForeignItemKind::Fn(fn_kind) => ItemKind::Fn(fn_kind),
3028 ForeignItemKind::TyAlias(ty_alias_kind) => ItemKind::TyAlias(ty_alias_kind),
3029 ForeignItemKind::MacCall(a) => ItemKind::MacCall(a),
3034 impl TryFrom<ItemKind> for ForeignItemKind {
3035 type Error = ItemKind;
3037 fn try_from(item_kind: ItemKind) -> Result<ForeignItemKind, ItemKind> {
3038 Ok(match item_kind {
3039 ItemKind::Static(a, b, c) => ForeignItemKind::Static(a, b, c),
3040 ItemKind::Fn(fn_kind) => ForeignItemKind::Fn(fn_kind),
3041 ItemKind::TyAlias(ty_alias_kind) => ForeignItemKind::TyAlias(ty_alias_kind),
3042 ItemKind::MacCall(a) => ForeignItemKind::MacCall(a),
3043 _ => return Err(item_kind),
3048 pub type ForeignItem = Item<ForeignItemKind>;
3050 // Some nodes are used a lot. Make sure they don't unintentionally get bigger.
3051 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
3054 use rustc_data_structures::static_assert_size;
3055 // tidy-alphabetical-start
3056 static_assert_size!(AssocItem, 104);
3057 static_assert_size!(AssocItemKind, 32);
3058 static_assert_size!(Attribute, 32);
3059 static_assert_size!(Block, 48);
3060 static_assert_size!(Expr, 72);
3061 static_assert_size!(ExprKind, 40);
3062 static_assert_size!(Fn, 184);
3063 static_assert_size!(ForeignItem, 96);
3064 static_assert_size!(ForeignItemKind, 24);
3065 static_assert_size!(GenericArg, 24);
3066 static_assert_size!(GenericBound, 72);
3067 static_assert_size!(Generics, 72);
3068 static_assert_size!(Impl, 184);
3069 static_assert_size!(Item, 184);
3070 static_assert_size!(ItemKind, 112);
3071 static_assert_size!(Lit, 48);
3072 static_assert_size!(LitKind, 24);
3073 static_assert_size!(Local, 72);
3074 static_assert_size!(Param, 40);
3075 static_assert_size!(Pat, 88);
3076 static_assert_size!(Path, 24);
3077 static_assert_size!(PathSegment, 24);
3078 static_assert_size!(PatKind, 64);
3079 static_assert_size!(Stmt, 32);
3080 static_assert_size!(StmtKind, 16);
3081 static_assert_size!(Ty, 64);
3082 static_assert_size!(TyKind, 40);
3083 // tidy-alphabetical-end