1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 pub use self::Variance::*;
12 pub use self::AssociatedItemContainer::*;
13 pub use self::BorrowKind::*;
14 pub use self::IntVarValue::*;
15 pub use self::fold::TypeFoldable;
17 use hir::{map as hir_map, FreevarMap, TraitMap};
18 use hir::def::{Def, CtorKind, ExportMap};
19 use hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
20 use hir::map::DefPathData;
23 use ich::StableHashingContext;
24 use middle::const_val::ConstVal;
25 use middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem};
26 use middle::privacy::AccessLevels;
27 use middle::resolve_lifetime::ObjectLifetimeDefault;
29 use mir::GeneratorLayout;
30 use session::CrateDisambiguator;
33 use ty::subst::{Subst, Substs};
34 use ty::util::IntTypeExt;
35 use ty::walk::TypeWalker;
36 use util::common::ErrorReported;
37 use util::nodemap::{NodeSet, DefIdMap, FxHashMap, FxHashSet};
39 use serialize::{self, Encodable, Encoder};
40 use std::cell::RefCell;
43 use std::hash::{Hash, Hasher};
44 use std::iter::FromIterator;
46 use rustc_data_structures::sync::Lrc;
48 use std::vec::IntoIter;
50 use syntax::ast::{self, DUMMY_NODE_ID, Name, Ident, NodeId};
52 use syntax::ext::hygiene::{Mark, SyntaxContext};
53 use syntax::symbol::{Symbol, InternedString};
54 use syntax_pos::{DUMMY_SP, Span};
55 use rustc_const_math::ConstInt;
57 use rustc_data_structures::accumulate_vec::IntoIter as AccIntoIter;
58 use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
63 pub use self::sty::{Binder, DebruijnIndex};
64 pub use self::sty::{FnSig, GenSig, PolyFnSig, PolyGenSig};
65 pub use self::sty::{InferTy, ParamTy, ProjectionTy, ExistentialPredicate};
66 pub use self::sty::{ClosureSubsts, GeneratorInterior, TypeAndMut};
67 pub use self::sty::{TraitRef, TypeVariants, PolyTraitRef};
68 pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
69 pub use self::sty::{ExistentialProjection, PolyExistentialProjection, Const};
70 pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
71 pub use self::sty::RegionKind;
72 pub use self::sty::{TyVid, IntVid, FloatVid, RegionVid};
73 pub use self::sty::BoundRegion::*;
74 pub use self::sty::InferTy::*;
75 pub use self::sty::RegionKind::*;
76 pub use self::sty::TypeVariants::*;
78 pub use self::binding::BindingMode;
79 pub use self::binding::BindingMode::*;
81 pub use self::context::{TyCtxt, GlobalArenas, AllArenas, tls, keep_local};
82 pub use self::context::{Lift, TypeckTables};
84 pub use self::instance::{Instance, InstanceDef};
86 pub use self::trait_def::TraitDef;
88 pub use self::maps::queries;
99 pub mod inhabitedness;
116 mod structural_impls;
121 /// The complete set of all analyses described in this module. This is
122 /// produced by the driver and fed to trans and later passes.
124 /// NB: These contents are being migrated into queries using the
125 /// *on-demand* infrastructure.
127 pub struct CrateAnalysis {
128 pub access_levels: Lrc<AccessLevels>,
130 pub glob_map: Option<hir::GlobMap>,
134 pub struct Resolutions {
135 pub freevars: FreevarMap,
136 pub trait_map: TraitMap,
137 pub maybe_unused_trait_imports: NodeSet,
138 pub maybe_unused_extern_crates: Vec<(NodeId, Span)>,
139 pub export_map: ExportMap,
142 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
143 pub enum AssociatedItemContainer {
144 TraitContainer(DefId),
145 ImplContainer(DefId),
148 impl AssociatedItemContainer {
149 /// Asserts that this is the def-id of an associated item declared
150 /// in a trait, and returns the trait def-id.
151 pub fn assert_trait(&self) -> DefId {
153 TraitContainer(id) => id,
154 _ => bug!("associated item has wrong container type: {:?}", self)
158 pub fn id(&self) -> DefId {
160 TraitContainer(id) => id,
161 ImplContainer(id) => id,
166 /// The "header" of an impl is everything outside the body: a Self type, a trait
167 /// ref (in the case of a trait impl), and a set of predicates (from the
168 /// bounds/where clauses).
169 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
170 pub struct ImplHeader<'tcx> {
171 pub impl_def_id: DefId,
172 pub self_ty: Ty<'tcx>,
173 pub trait_ref: Option<TraitRef<'tcx>>,
174 pub predicates: Vec<Predicate<'tcx>>,
177 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
178 pub struct AssociatedItem {
181 pub kind: AssociatedKind,
183 pub defaultness: hir::Defaultness,
184 pub container: AssociatedItemContainer,
186 /// Whether this is a method with an explicit self
187 /// as its first argument, allowing method calls.
188 pub method_has_self_argument: bool,
191 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash, RustcEncodable, RustcDecodable)]
192 pub enum AssociatedKind {
198 impl AssociatedItem {
199 pub fn def(&self) -> Def {
201 AssociatedKind::Const => Def::AssociatedConst(self.def_id),
202 AssociatedKind::Method => Def::Method(self.def_id),
203 AssociatedKind::Type => Def::AssociatedTy(self.def_id),
207 /// Tests whether the associated item admits a non-trivial implementation
209 pub fn relevant_for_never<'tcx>(&self) -> bool {
211 AssociatedKind::Const => true,
212 AssociatedKind::Type => true,
213 // FIXME(canndrew): Be more thorough here, check if any argument is uninhabited.
214 AssociatedKind::Method => !self.method_has_self_argument,
218 pub fn signature<'a, 'tcx>(&self, tcx: &TyCtxt<'a, 'tcx, 'tcx>) -> String {
220 ty::AssociatedKind::Method => {
221 // We skip the binder here because the binder would deanonymize all
222 // late-bound regions, and we don't want method signatures to show up
223 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
224 // regions just fine, showing `fn(&MyType)`.
225 format!("{}", tcx.fn_sig(self.def_id).skip_binder())
227 ty::AssociatedKind::Type => format!("type {};", self.name.to_string()),
228 ty::AssociatedKind::Const => {
229 format!("const {}: {:?};", self.name.to_string(), tcx.type_of(self.def_id))
235 #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable)]
236 pub enum Visibility {
237 /// Visible everywhere (including in other crates).
239 /// Visible only in the given crate-local module.
241 /// Not visible anywhere in the local crate. This is the visibility of private external items.
245 pub trait DefIdTree: Copy {
246 fn parent(self, id: DefId) -> Option<DefId>;
248 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
249 if descendant.krate != ancestor.krate {
253 while descendant != ancestor {
254 match self.parent(descendant) {
255 Some(parent) => descendant = parent,
256 None => return false,
263 impl<'a, 'gcx, 'tcx> DefIdTree for TyCtxt<'a, 'gcx, 'tcx> {
264 fn parent(self, id: DefId) -> Option<DefId> {
265 self.def_key(id).parent.map(|index| DefId { index: index, ..id })
270 pub fn from_hir(visibility: &hir::Visibility, id: NodeId, tcx: TyCtxt) -> Self {
272 hir::Public => Visibility::Public,
273 hir::Visibility::Crate => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
274 hir::Visibility::Restricted { ref path, .. } => match path.def {
275 // If there is no resolution, `resolve` will have already reported an error, so
276 // assume that the visibility is public to avoid reporting more privacy errors.
277 Def::Err => Visibility::Public,
278 def => Visibility::Restricted(def.def_id()),
281 Visibility::Restricted(tcx.hir.get_module_parent(id))
286 /// Returns true if an item with this visibility is accessible from the given block.
287 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
288 let restriction = match self {
289 // Public items are visible everywhere.
290 Visibility::Public => return true,
291 // Private items from other crates are visible nowhere.
292 Visibility::Invisible => return false,
293 // Restricted items are visible in an arbitrary local module.
294 Visibility::Restricted(other) if other.krate != module.krate => return false,
295 Visibility::Restricted(module) => module,
298 tree.is_descendant_of(module, restriction)
301 /// Returns true if this visibility is at least as accessible as the given visibility
302 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
303 let vis_restriction = match vis {
304 Visibility::Public => return self == Visibility::Public,
305 Visibility::Invisible => return true,
306 Visibility::Restricted(module) => module,
309 self.is_accessible_from(vis_restriction, tree)
312 // Returns true if this item is visible anywhere in the local crate.
313 pub fn is_visible_locally(self) -> bool {
315 Visibility::Public => true,
316 Visibility::Restricted(def_id) => def_id.is_local(),
317 Visibility::Invisible => false,
322 #[derive(Clone, PartialEq, RustcDecodable, RustcEncodable, Copy)]
324 Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
325 Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
326 Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
327 Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
330 /// The crate variances map is computed during typeck and contains the
331 /// variance of every item in the local crate. You should not use it
332 /// directly, because to do so will make your pass dependent on the
333 /// HIR of every item in the local crate. Instead, use
334 /// `tcx.variances_of()` to get the variance for a *particular*
336 pub struct CrateVariancesMap {
337 /// For each item with generics, maps to a vector of the variance
338 /// of its generics. If an item has no generics, it will have no
340 pub variances: FxHashMap<DefId, Lrc<Vec<ty::Variance>>>,
342 /// An empty vector, useful for cloning.
343 pub empty_variance: Lrc<Vec<ty::Variance>>,
347 /// `a.xform(b)` combines the variance of a context with the
348 /// variance of a type with the following meaning. If we are in a
349 /// context with variance `a`, and we encounter a type argument in
350 /// a position with variance `b`, then `a.xform(b)` is the new
351 /// variance with which the argument appears.
357 /// Here, the "ambient" variance starts as covariant. `*mut T` is
358 /// invariant with respect to `T`, so the variance in which the
359 /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which
360 /// yields `Invariant`. Now, the type `Vec<T>` is covariant with
361 /// respect to its type argument `T`, and hence the variance of
362 /// the `i32` here is `Invariant.xform(Covariant)`, which results
363 /// (again) in `Invariant`.
367 /// fn(*const Vec<i32>, *mut Vec<i32)
369 /// The ambient variance is covariant. A `fn` type is
370 /// contravariant with respect to its parameters, so the variance
371 /// within which both pointer types appear is
372 /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const
373 /// T` is covariant with respect to `T`, so the variance within
374 /// which the first `Vec<i32>` appears is
375 /// `Contravariant.xform(Covariant)` or `Contravariant`. The same
376 /// is true for its `i32` argument. In the `*mut T` case, the
377 /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`,
378 /// and hence the outermost type is `Invariant` with respect to
379 /// `Vec<i32>` (and its `i32` argument).
381 /// Source: Figure 1 of "Taming the Wildcards:
382 /// Combining Definition- and Use-Site Variance" published in PLDI'11.
383 pub fn xform(self, v: ty::Variance) -> ty::Variance {
385 // Figure 1, column 1.
386 (ty::Covariant, ty::Covariant) => ty::Covariant,
387 (ty::Covariant, ty::Contravariant) => ty::Contravariant,
388 (ty::Covariant, ty::Invariant) => ty::Invariant,
389 (ty::Covariant, ty::Bivariant) => ty::Bivariant,
391 // Figure 1, column 2.
392 (ty::Contravariant, ty::Covariant) => ty::Contravariant,
393 (ty::Contravariant, ty::Contravariant) => ty::Covariant,
394 (ty::Contravariant, ty::Invariant) => ty::Invariant,
395 (ty::Contravariant, ty::Bivariant) => ty::Bivariant,
397 // Figure 1, column 3.
398 (ty::Invariant, _) => ty::Invariant,
400 // Figure 1, column 4.
401 (ty::Bivariant, _) => ty::Bivariant,
406 // Contains information needed to resolve types and (in the future) look up
407 // the types of AST nodes.
408 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
409 pub struct CReaderCacheKey {
414 // Flags that we track on types. These flags are propagated upwards
415 // through the type during type construction, so that we can quickly
416 // check whether the type has various kinds of types in it without
417 // recursing over the type itself.
419 pub struct TypeFlags: u32 {
420 const HAS_PARAMS = 1 << 0;
421 const HAS_SELF = 1 << 1;
422 const HAS_TY_INFER = 1 << 2;
423 const HAS_RE_INFER = 1 << 3;
424 const HAS_RE_SKOL = 1 << 4;
426 /// Does this have any `ReEarlyBound` regions? Used to
427 /// determine whether substitition is required, since those
428 /// represent regions that are bound in a `ty::Generics` and
429 /// hence may be substituted.
430 const HAS_RE_EARLY_BOUND = 1 << 5;
432 /// Does this have any region that "appears free" in the type?
433 /// Basically anything but `ReLateBound` and `ReErased`.
434 const HAS_FREE_REGIONS = 1 << 6;
436 /// Is an error type reachable?
437 const HAS_TY_ERR = 1 << 7;
438 const HAS_PROJECTION = 1 << 8;
440 // FIXME: Rename this to the actual property since it's used for generators too
441 const HAS_TY_CLOSURE = 1 << 9;
443 // true if there are "names" of types and regions and so forth
444 // that are local to a particular fn
445 const HAS_LOCAL_NAMES = 1 << 10;
447 // Present if the type belongs in a local type context.
448 // Only set for TyInfer other than Fresh.
449 const KEEP_IN_LOCAL_TCX = 1 << 11;
451 // Is there a projection that does not involve a bound region?
452 // Currently we can't normalize projections w/ bound regions.
453 const HAS_NORMALIZABLE_PROJECTION = 1 << 12;
455 const NEEDS_SUBST = TypeFlags::HAS_PARAMS.bits |
456 TypeFlags::HAS_SELF.bits |
457 TypeFlags::HAS_RE_EARLY_BOUND.bits;
459 // Flags representing the nominal content of a type,
460 // computed by FlagsComputation. If you add a new nominal
461 // flag, it should be added here too.
462 const NOMINAL_FLAGS = TypeFlags::HAS_PARAMS.bits |
463 TypeFlags::HAS_SELF.bits |
464 TypeFlags::HAS_TY_INFER.bits |
465 TypeFlags::HAS_RE_INFER.bits |
466 TypeFlags::HAS_RE_SKOL.bits |
467 TypeFlags::HAS_RE_EARLY_BOUND.bits |
468 TypeFlags::HAS_FREE_REGIONS.bits |
469 TypeFlags::HAS_TY_ERR.bits |
470 TypeFlags::HAS_PROJECTION.bits |
471 TypeFlags::HAS_TY_CLOSURE.bits |
472 TypeFlags::HAS_LOCAL_NAMES.bits |
473 TypeFlags::KEEP_IN_LOCAL_TCX.bits;
477 pub struct TyS<'tcx> {
478 pub sty: TypeVariants<'tcx>,
479 pub flags: TypeFlags,
481 // the maximal depth of any bound regions appearing in this type.
485 impl<'tcx> PartialEq for TyS<'tcx> {
487 fn eq(&self, other: &TyS<'tcx>) -> bool {
488 // (self as *const _) == (other as *const _)
489 (self as *const TyS<'tcx>) == (other as *const TyS<'tcx>)
492 impl<'tcx> Eq for TyS<'tcx> {}
494 impl<'tcx> Hash for TyS<'tcx> {
495 fn hash<H: Hasher>(&self, s: &mut H) {
496 (self as *const TyS).hash(s)
500 impl<'tcx> TyS<'tcx> {
501 pub fn is_primitive_ty(&self) -> bool {
503 TypeVariants::TyBool |
504 TypeVariants::TyChar |
505 TypeVariants::TyInt(_) |
506 TypeVariants::TyUint(_) |
507 TypeVariants::TyFloat(_) |
508 TypeVariants::TyInfer(InferTy::IntVar(_)) |
509 TypeVariants::TyInfer(InferTy::FloatVar(_)) |
510 TypeVariants::TyInfer(InferTy::FreshIntTy(_)) |
511 TypeVariants::TyInfer(InferTy::FreshFloatTy(_)) => true,
512 TypeVariants::TyRef(_, x) => x.ty.is_primitive_ty(),
517 pub fn is_suggestable(&self) -> bool {
519 TypeVariants::TyAnon(..) |
520 TypeVariants::TyFnDef(..) |
521 TypeVariants::TyFnPtr(..) |
522 TypeVariants::TyDynamic(..) |
523 TypeVariants::TyClosure(..) |
524 TypeVariants::TyInfer(..) |
525 TypeVariants::TyProjection(..) => false,
531 impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::TyS<'gcx> {
532 fn hash_stable<W: StableHasherResult>(&self,
533 hcx: &mut StableHashingContext<'gcx>,
534 hasher: &mut StableHasher<W>) {
538 // The other fields just provide fast access to information that is
539 // also contained in `sty`, so no need to hash them.
544 sty.hash_stable(hcx, hasher);
548 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
550 impl<'tcx> serialize::UseSpecializedEncodable for Ty<'tcx> {}
551 impl<'tcx> serialize::UseSpecializedDecodable for Ty<'tcx> {}
553 /// A wrapper for slices with the additional invariant
554 /// that the slice is interned and no other slice with
555 /// the same contents can exist in the same context.
556 /// This means we can use pointer + length for both
557 /// equality comparisons and hashing.
558 #[derive(Debug, RustcEncodable)]
559 pub struct Slice<T>([T]);
561 impl<T> PartialEq for Slice<T> {
563 fn eq(&self, other: &Slice<T>) -> bool {
564 (&self.0 as *const [T]) == (&other.0 as *const [T])
567 impl<T> Eq for Slice<T> {}
569 impl<T> Hash for Slice<T> {
570 fn hash<H: Hasher>(&self, s: &mut H) {
571 (self.as_ptr(), self.len()).hash(s)
575 impl<T> Deref for Slice<T> {
577 fn deref(&self) -> &[T] {
582 impl<'a, T> IntoIterator for &'a Slice<T> {
584 type IntoIter = <&'a [T] as IntoIterator>::IntoIter;
585 fn into_iter(self) -> Self::IntoIter {
590 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Slice<Ty<'tcx>> {}
593 pub fn empty<'a>() -> &'a Slice<T> {
595 mem::transmute(slice::from_raw_parts(0x1 as *const T, 0))
600 /// Upvars do not get their own node-id. Instead, we use the pair of
601 /// the original var id (that is, the root variable that is referenced
602 /// by the upvar) and the id of the closure expression.
603 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
605 pub var_id: hir::HirId,
606 pub closure_expr_id: LocalDefId,
609 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, Copy)]
610 pub enum BorrowKind {
611 /// Data must be immutable and is aliasable.
614 /// Data must be immutable but not aliasable. This kind of borrow
615 /// cannot currently be expressed by the user and is used only in
616 /// implicit closure bindings. It is needed when the closure
617 /// is borrowing or mutating a mutable referent, e.g.:
619 /// let x: &mut isize = ...;
620 /// let y = || *x += 5;
622 /// If we were to try to translate this closure into a more explicit
623 /// form, we'd encounter an error with the code as written:
625 /// struct Env { x: & &mut isize }
626 /// let x: &mut isize = ...;
627 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
628 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
630 /// This is then illegal because you cannot mutate a `&mut` found
631 /// in an aliasable location. To solve, you'd have to translate with
632 /// an `&mut` borrow:
634 /// struct Env { x: & &mut isize }
635 /// let x: &mut isize = ...;
636 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
637 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
639 /// Now the assignment to `**env.x` is legal, but creating a
640 /// mutable pointer to `x` is not because `x` is not mutable. We
641 /// could fix this by declaring `x` as `let mut x`. This is ok in
642 /// user code, if awkward, but extra weird for closures, since the
643 /// borrow is hidden.
645 /// So we introduce a "unique imm" borrow -- the referent is
646 /// immutable, but not aliasable. This solves the problem. For
647 /// simplicity, we don't give users the way to express this
648 /// borrow, it's just used when translating closures.
651 /// Data is mutable and not aliasable.
655 /// Information describing the capture of an upvar. This is computed
656 /// during `typeck`, specifically by `regionck`.
657 #[derive(PartialEq, Clone, Debug, Copy, RustcEncodable, RustcDecodable)]
658 pub enum UpvarCapture<'tcx> {
659 /// Upvar is captured by value. This is always true when the
660 /// closure is labeled `move`, but can also be true in other cases
661 /// depending on inference.
664 /// Upvar is captured by reference.
665 ByRef(UpvarBorrow<'tcx>),
668 #[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable)]
669 pub struct UpvarBorrow<'tcx> {
670 /// The kind of borrow: by-ref upvars have access to shared
671 /// immutable borrows, which are not part of the normal language
673 pub kind: BorrowKind,
675 /// Region of the resulting reference.
676 pub region: ty::Region<'tcx>,
679 pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
681 #[derive(Copy, Clone)]
682 pub struct ClosureUpvar<'tcx> {
688 #[derive(Clone, Copy, PartialEq, Eq)]
689 pub enum IntVarValue {
691 UintType(ast::UintTy),
694 #[derive(Clone, Copy, PartialEq, Eq)]
695 pub struct FloatVarValue(pub ast::FloatTy);
697 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
698 pub struct TypeParameterDef {
702 pub has_default: bool,
703 pub object_lifetime_default: ObjectLifetimeDefault,
705 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
706 /// on generic parameter `T`, asserts data behind the parameter
707 /// `T` won't be accessed during the parent type's `Drop` impl.
708 pub pure_wrt_drop: bool,
710 pub synthetic: Option<hir::SyntheticTyParamKind>,
713 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
714 pub struct RegionParameterDef {
719 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
720 /// on generic parameter `'a`, asserts data of lifetime `'a`
721 /// won't be accessed during the parent type's `Drop` impl.
722 pub pure_wrt_drop: bool,
725 impl RegionParameterDef {
726 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
727 ty::EarlyBoundRegion {
734 pub fn to_bound_region(&self) -> ty::BoundRegion {
735 self.to_early_bound_region_data().to_bound_region()
739 impl ty::EarlyBoundRegion {
740 pub fn to_bound_region(&self) -> ty::BoundRegion {
741 ty::BoundRegion::BrNamed(self.def_id, self.name)
745 /// Information about the formal type/lifetime parameters associated
746 /// with an item or method. Analogous to hir::Generics.
748 /// Note that in the presence of a `Self` parameter, the ordering here
749 /// is different from the ordering in a Substs. Substs are ordered as
750 /// Self, *Regions, *Other Type Params, (...child generics)
751 /// while this struct is ordered as
752 /// regions = Regions
753 /// types = [Self, *Other Type Params]
754 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
755 pub struct Generics {
756 pub parent: Option<DefId>,
757 pub parent_regions: u32,
758 pub parent_types: u32,
759 pub regions: Vec<RegionParameterDef>,
760 pub types: Vec<TypeParameterDef>,
762 /// Reverse map to each `TypeParameterDef`'s `index` field
763 pub type_param_to_index: FxHashMap<DefId, u32>,
766 pub has_late_bound_regions: Option<Span>,
769 impl<'a, 'gcx, 'tcx> Generics {
770 pub fn parent_count(&self) -> usize {
771 self.parent_regions as usize + self.parent_types as usize
774 pub fn own_count(&self) -> usize {
775 self.regions.len() + self.types.len()
778 pub fn count(&self) -> usize {
779 self.parent_count() + self.own_count()
782 pub fn region_param(&'tcx self,
783 param: &EarlyBoundRegion,
784 tcx: TyCtxt<'a, 'gcx, 'tcx>)
785 -> &'tcx RegionParameterDef
787 if let Some(index) = param.index.checked_sub(self.parent_count() as u32) {
788 &self.regions[index as usize - self.has_self as usize]
790 tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
791 .region_param(param, tcx)
795 /// Returns the `TypeParameterDef` associated with this `ParamTy`.
796 pub fn type_param(&'tcx self,
798 tcx: TyCtxt<'a, 'gcx, 'tcx>)
799 -> &TypeParameterDef {
800 if let Some(idx) = param.idx.checked_sub(self.parent_count() as u32) {
801 // non-Self type parameters are always offset by exactly
802 // `self.regions.len()`. In the absence of a Self, this is obvious,
803 // but even in the presence of a `Self` we just have to "compensate"
806 // Without a `Self` (or in a nested generics that doesn't have
807 // a `Self` in itself, even through it parent does), for example
808 // for `fn foo<'a, T1, T2>()`, the situation is:
816 // And with a `Self`, for example for `trait Foo<'a, 'b, T1, T2>`, the
825 // And it can be seen that in both cases, to move from a substs
826 // offset to a generics offset you just have to offset by the
827 // number of regions.
828 let type_param_offset = self.regions.len();
830 let has_self = self.has_self && self.parent.is_none();
831 let is_separated_self = type_param_offset != 0 && idx == 0 && has_self;
833 if let Some(idx) = (idx as usize).checked_sub(type_param_offset) {
834 assert!(!is_separated_self, "found a Self after type_param_offset");
837 assert!(is_separated_self, "non-Self param before type_param_offset");
841 tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
842 .type_param(param, tcx)
847 /// Bounds on generics.
848 #[derive(Clone, Default)]
849 pub struct GenericPredicates<'tcx> {
850 pub parent: Option<DefId>,
851 pub predicates: Vec<Predicate<'tcx>>,
854 impl<'tcx> serialize::UseSpecializedEncodable for GenericPredicates<'tcx> {}
855 impl<'tcx> serialize::UseSpecializedDecodable for GenericPredicates<'tcx> {}
857 impl<'a, 'gcx, 'tcx> GenericPredicates<'tcx> {
858 pub fn instantiate(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>)
859 -> InstantiatedPredicates<'tcx> {
860 let mut instantiated = InstantiatedPredicates::empty();
861 self.instantiate_into(tcx, &mut instantiated, substs);
864 pub fn instantiate_own(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>)
865 -> InstantiatedPredicates<'tcx> {
866 InstantiatedPredicates {
867 predicates: self.predicates.subst(tcx, substs)
871 fn instantiate_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
872 instantiated: &mut InstantiatedPredicates<'tcx>,
873 substs: &Substs<'tcx>) {
874 if let Some(def_id) = self.parent {
875 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
877 instantiated.predicates.extend(self.predicates.iter().map(|p| p.subst(tcx, substs)))
880 pub fn instantiate_identity(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>)
881 -> InstantiatedPredicates<'tcx> {
882 let mut instantiated = InstantiatedPredicates::empty();
883 self.instantiate_identity_into(tcx, &mut instantiated);
887 fn instantiate_identity_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
888 instantiated: &mut InstantiatedPredicates<'tcx>) {
889 if let Some(def_id) = self.parent {
890 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
892 instantiated.predicates.extend(&self.predicates)
895 pub fn instantiate_supertrait(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
896 poly_trait_ref: &ty::PolyTraitRef<'tcx>)
897 -> InstantiatedPredicates<'tcx>
899 assert_eq!(self.parent, None);
900 InstantiatedPredicates {
901 predicates: self.predicates.iter().map(|pred| {
902 pred.subst_supertrait(tcx, poly_trait_ref)
908 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
909 pub enum Predicate<'tcx> {
910 /// Corresponds to `where Foo : Bar<A,B,C>`. `Foo` here would be
911 /// the `Self` type of the trait reference and `A`, `B`, and `C`
912 /// would be the type parameters.
913 Trait(PolyTraitPredicate<'tcx>),
916 RegionOutlives(PolyRegionOutlivesPredicate<'tcx>),
919 TypeOutlives(PolyTypeOutlivesPredicate<'tcx>),
921 /// where <T as TraitRef>::Name == X, approximately.
922 /// See `ProjectionPredicate` struct for details.
923 Projection(PolyProjectionPredicate<'tcx>),
926 WellFormed(Ty<'tcx>),
928 /// trait must be object-safe
931 /// No direct syntax. May be thought of as `where T : FnFoo<...>`
932 /// for some substitutions `...` and T being a closure type.
933 /// Satisfied (or refuted) once we know the closure's kind.
934 ClosureKind(DefId, ClosureSubsts<'tcx>, ClosureKind),
937 Subtype(PolySubtypePredicate<'tcx>),
939 /// Constant initializer must evaluate successfully.
940 ConstEvaluatable(DefId, &'tcx Substs<'tcx>),
943 impl<'tcx> AsRef<Predicate<'tcx>> for Predicate<'tcx> {
944 fn as_ref(&self) -> &Predicate<'tcx> {
949 impl<'a, 'gcx, 'tcx> Predicate<'tcx> {
950 /// Performs a substitution suitable for going from a
951 /// poly-trait-ref to supertraits that must hold if that
952 /// poly-trait-ref holds. This is slightly different from a normal
953 /// substitution in terms of what happens with bound regions. See
954 /// lengthy comment below for details.
955 pub fn subst_supertrait(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
956 trait_ref: &ty::PolyTraitRef<'tcx>)
957 -> ty::Predicate<'tcx>
959 // The interaction between HRTB and supertraits is not entirely
960 // obvious. Let me walk you (and myself) through an example.
962 // Let's start with an easy case. Consider two traits:
964 // trait Foo<'a> : Bar<'a,'a> { }
965 // trait Bar<'b,'c> { }
967 // Now, if we have a trait reference `for<'x> T : Foo<'x>`, then
968 // we can deduce that `for<'x> T : Bar<'x,'x>`. Basically, if we
969 // knew that `Foo<'x>` (for any 'x) then we also know that
970 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
971 // normal substitution.
973 // In terms of why this is sound, the idea is that whenever there
974 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
975 // holds. So if there is an impl of `T:Foo<'a>` that applies to
976 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
979 // Another example to be careful of is this:
981 // trait Foo1<'a> : for<'b> Bar1<'a,'b> { }
982 // trait Bar1<'b,'c> { }
984 // Here, if we have `for<'x> T : Foo1<'x>`, then what do we know?
985 // The answer is that we know `for<'x,'b> T : Bar1<'x,'b>`. The
986 // reason is similar to the previous example: any impl of
987 // `T:Foo1<'x>` must show that `for<'b> T : Bar1<'x, 'b>`. So
988 // basically we would want to collapse the bound lifetimes from
989 // the input (`trait_ref`) and the supertraits.
991 // To achieve this in practice is fairly straightforward. Let's
992 // consider the more complicated scenario:
994 // - We start out with `for<'x> T : Foo1<'x>`. In this case, `'x`
995 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T : Bar1<'x,'b>`,
996 // where both `'x` and `'b` would have a DB index of 1.
997 // The substitution from the input trait-ref is therefore going to be
998 // `'a => 'x` (where `'x` has a DB index of 1).
999 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1000 // early-bound parameter and `'b' is a late-bound parameter with a
1002 // - If we replace `'a` with `'x` from the input, it too will have
1003 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1004 // just as we wanted.
1006 // There is only one catch. If we just apply the substitution `'a
1007 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1008 // adjust the DB index because we substituting into a binder (it
1009 // tries to be so smart...) resulting in `for<'x> for<'b>
1010 // Bar1<'x,'b>` (we have no syntax for this, so use your
1011 // imagination). Basically the 'x will have DB index of 2 and 'b
1012 // will have DB index of 1. Not quite what we want. So we apply
1013 // the substitution to the *contents* of the trait reference,
1014 // rather than the trait reference itself (put another way, the
1015 // substitution code expects equal binding levels in the values
1016 // from the substitution and the value being substituted into, and
1017 // this trick achieves that).
1019 let substs = &trait_ref.0.substs;
1021 Predicate::Trait(ty::Binder(ref data)) =>
1022 Predicate::Trait(ty::Binder(data.subst(tcx, substs))),
1023 Predicate::Subtype(ty::Binder(ref data)) =>
1024 Predicate::Subtype(ty::Binder(data.subst(tcx, substs))),
1025 Predicate::RegionOutlives(ty::Binder(ref data)) =>
1026 Predicate::RegionOutlives(ty::Binder(data.subst(tcx, substs))),
1027 Predicate::TypeOutlives(ty::Binder(ref data)) =>
1028 Predicate::TypeOutlives(ty::Binder(data.subst(tcx, substs))),
1029 Predicate::Projection(ty::Binder(ref data)) =>
1030 Predicate::Projection(ty::Binder(data.subst(tcx, substs))),
1031 Predicate::WellFormed(data) =>
1032 Predicate::WellFormed(data.subst(tcx, substs)),
1033 Predicate::ObjectSafe(trait_def_id) =>
1034 Predicate::ObjectSafe(trait_def_id),
1035 Predicate::ClosureKind(closure_def_id, closure_substs, kind) =>
1036 Predicate::ClosureKind(closure_def_id, closure_substs.subst(tcx, substs), kind),
1037 Predicate::ConstEvaluatable(def_id, const_substs) =>
1038 Predicate::ConstEvaluatable(def_id, const_substs.subst(tcx, substs)),
1043 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1044 pub struct TraitPredicate<'tcx> {
1045 pub trait_ref: TraitRef<'tcx>
1047 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1049 impl<'tcx> TraitPredicate<'tcx> {
1050 pub fn def_id(&self) -> DefId {
1051 self.trait_ref.def_id
1054 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
1055 self.trait_ref.input_types()
1058 pub fn self_ty(&self) -> Ty<'tcx> {
1059 self.trait_ref.self_ty()
1063 impl<'tcx> PolyTraitPredicate<'tcx> {
1064 pub fn def_id(&self) -> DefId {
1065 // ok to skip binder since trait def-id does not care about regions
1070 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1071 pub struct OutlivesPredicate<A,B>(pub A, pub B); // `A : B`
1072 pub type PolyOutlivesPredicate<A,B> = ty::Binder<OutlivesPredicate<A,B>>;
1073 pub type PolyRegionOutlivesPredicate<'tcx> = PolyOutlivesPredicate<ty::Region<'tcx>,
1075 pub type PolyTypeOutlivesPredicate<'tcx> = PolyOutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1077 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1078 pub struct SubtypePredicate<'tcx> {
1079 pub a_is_expected: bool,
1083 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1085 /// This kind of predicate has no *direct* correspondent in the
1086 /// syntax, but it roughly corresponds to the syntactic forms:
1088 /// 1. `T : TraitRef<..., Item=Type>`
1089 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1091 /// In particular, form #1 is "desugared" to the combination of a
1092 /// normal trait predicate (`T : TraitRef<...>`) and one of these
1093 /// predicates. Form #2 is a broader form in that it also permits
1094 /// equality between arbitrary types. Processing an instance of
1095 /// Form #2 eventually yields one of these `ProjectionPredicate`
1096 /// instances to normalize the LHS.
1097 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1098 pub struct ProjectionPredicate<'tcx> {
1099 pub projection_ty: ProjectionTy<'tcx>,
1103 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1105 impl<'tcx> PolyProjectionPredicate<'tcx> {
1106 pub fn to_poly_trait_ref(&self, tcx: TyCtxt) -> PolyTraitRef<'tcx> {
1107 // Note: unlike with TraitRef::to_poly_trait_ref(),
1108 // self.0.trait_ref is permitted to have escaping regions.
1109 // This is because here `self` has a `Binder` and so does our
1110 // return value, so we are preserving the number of binding
1112 ty::Binder(self.0.projection_ty.trait_ref(tcx))
1115 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1116 Binder(self.skip_binder().ty) // preserves binding levels
1120 pub trait ToPolyTraitRef<'tcx> {
1121 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1124 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1125 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1126 assert!(!self.has_escaping_regions());
1127 ty::Binder(self.clone())
1131 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1132 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1133 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1137 pub trait ToPredicate<'tcx> {
1138 fn to_predicate(&self) -> Predicate<'tcx>;
1141 impl<'tcx> ToPredicate<'tcx> for TraitRef<'tcx> {
1142 fn to_predicate(&self) -> Predicate<'tcx> {
1143 // we're about to add a binder, so let's check that we don't
1144 // accidentally capture anything, or else that might be some
1145 // weird debruijn accounting.
1146 assert!(!self.has_escaping_regions());
1148 ty::Predicate::Trait(ty::Binder(ty::TraitPredicate {
1149 trait_ref: self.clone()
1154 impl<'tcx> ToPredicate<'tcx> for PolyTraitRef<'tcx> {
1155 fn to_predicate(&self) -> Predicate<'tcx> {
1156 ty::Predicate::Trait(self.to_poly_trait_predicate())
1160 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1161 fn to_predicate(&self) -> Predicate<'tcx> {
1162 Predicate::RegionOutlives(self.clone())
1166 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1167 fn to_predicate(&self) -> Predicate<'tcx> {
1168 Predicate::TypeOutlives(self.clone())
1172 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1173 fn to_predicate(&self) -> Predicate<'tcx> {
1174 Predicate::Projection(self.clone())
1178 impl<'tcx> Predicate<'tcx> {
1179 /// Iterates over the types in this predicate. Note that in all
1180 /// cases this is skipping over a binder, so late-bound regions
1181 /// with depth 0 are bound by the predicate.
1182 pub fn walk_tys(&self) -> IntoIter<Ty<'tcx>> {
1183 let vec: Vec<_> = match *self {
1184 ty::Predicate::Trait(ref data) => {
1185 data.skip_binder().input_types().collect()
1187 ty::Predicate::Subtype(ty::Binder(SubtypePredicate { a, b, a_is_expected: _ })) => {
1190 ty::Predicate::TypeOutlives(ty::Binder(ref data)) => {
1193 ty::Predicate::RegionOutlives(..) => {
1196 ty::Predicate::Projection(ref data) => {
1197 data.0.projection_ty.substs.types().chain(Some(data.0.ty)).collect()
1199 ty::Predicate::WellFormed(data) => {
1202 ty::Predicate::ObjectSafe(_trait_def_id) => {
1205 ty::Predicate::ClosureKind(_closure_def_id, closure_substs, _kind) => {
1206 closure_substs.substs.types().collect()
1208 ty::Predicate::ConstEvaluatable(_, substs) => {
1209 substs.types().collect()
1213 // The only reason to collect into a vector here is that I was
1214 // too lazy to make the full (somewhat complicated) iterator
1215 // type that would be needed here. But I wanted this fn to
1216 // return an iterator conceptually, rather than a `Vec`, so as
1217 // to be closer to `Ty::walk`.
1221 pub fn to_opt_poly_trait_ref(&self) -> Option<PolyTraitRef<'tcx>> {
1223 Predicate::Trait(ref t) => {
1224 Some(t.to_poly_trait_ref())
1226 Predicate::Projection(..) |
1227 Predicate::Subtype(..) |
1228 Predicate::RegionOutlives(..) |
1229 Predicate::WellFormed(..) |
1230 Predicate::ObjectSafe(..) |
1231 Predicate::ClosureKind(..) |
1232 Predicate::TypeOutlives(..) |
1233 Predicate::ConstEvaluatable(..) => {
1239 pub fn to_opt_type_outlives(&self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1241 Predicate::TypeOutlives(data) => {
1244 Predicate::Trait(..) |
1245 Predicate::Projection(..) |
1246 Predicate::Subtype(..) |
1247 Predicate::RegionOutlives(..) |
1248 Predicate::WellFormed(..) |
1249 Predicate::ObjectSafe(..) |
1250 Predicate::ClosureKind(..) |
1251 Predicate::ConstEvaluatable(..) => {
1258 /// Represents the bounds declared on a particular set of type
1259 /// parameters. Should eventually be generalized into a flag list of
1260 /// where clauses. You can obtain a `InstantiatedPredicates` list from a
1261 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1262 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1263 /// the `GenericPredicates` are expressed in terms of the bound type
1264 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1265 /// represented a set of bounds for some particular instantiation,
1266 /// meaning that the generic parameters have been substituted with
1271 /// struct Foo<T,U:Bar<T>> { ... }
1273 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1274 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1275 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1276 /// [usize:Bar<isize>]]`.
1278 pub struct InstantiatedPredicates<'tcx> {
1279 pub predicates: Vec<Predicate<'tcx>>,
1282 impl<'tcx> InstantiatedPredicates<'tcx> {
1283 pub fn empty() -> InstantiatedPredicates<'tcx> {
1284 InstantiatedPredicates { predicates: vec![] }
1287 pub fn is_empty(&self) -> bool {
1288 self.predicates.is_empty()
1292 /// "Universes" are used during type- and trait-checking in the
1293 /// presence of `for<..>` binders to control what sets of names are
1294 /// visible. Universes are arranged into a tree: the root universe
1295 /// contains names that are always visible. But when you enter into
1296 /// some subuniverse, then it may add names that are only visible
1297 /// within that subtree (but it can still name the names of its
1298 /// ancestor universes).
1300 /// To make this more concrete, consider this program:
1304 /// fn bar<T>(x: T) {
1305 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1309 /// The struct name `Foo` is in the root universe U0. But the type
1310 /// parameter `T`, introduced on `bar`, is in a subuniverse U1 --
1311 /// i.e., within `bar`, we can name both `T` and `Foo`, but outside of
1312 /// `bar`, we cannot name `T`. Then, within the type of `y`, the
1313 /// region `'a` is in a subuniverse U2 of U1, because we can name it
1314 /// inside the fn type but not outside.
1316 /// Universes are related to **skolemization** -- which is a way of
1317 /// doing type- and trait-checking around these "forall" binders (also
1318 /// called **universal quantification**). The idea is that when, in
1319 /// the body of `bar`, we refer to `T` as a type, we aren't referring
1320 /// to any type in particular, but rather a kind of "fresh" type that
1321 /// is distinct from all other types we have actually declared. This
1322 /// is called a **skolemized** type, and we use universes to talk
1323 /// about this. In other words, a type name in universe 0 always
1324 /// corresponds to some "ground" type that the user declared, but a
1325 /// type name in a non-zero universe is a skolemized type -- an
1326 /// idealized representative of "types in general" that we use for
1327 /// checking generic functions.
1328 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1329 pub struct UniverseIndex(u32);
1331 impl UniverseIndex {
1332 /// The root universe, where things that the user defined are
1334 pub const ROOT: UniverseIndex = UniverseIndex(0);
1336 /// A "subuniverse" corresponds to being inside a `forall` quantifier.
1337 /// So, for example, suppose we have this type in universe `U`:
1340 /// for<'a> fn(&'a u32)
1343 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1344 /// subuniverse of `U` -- in this new universe, we can name the
1345 /// region `'a`, but that region was not nameable from `U` because
1346 /// it was not in scope there.
1347 pub fn subuniverse(self) -> UniverseIndex {
1348 UniverseIndex(self.0.checked_add(1).unwrap())
1351 pub fn from(v: u32) -> UniverseIndex {
1355 pub fn as_u32(&self) -> u32 {
1359 pub fn as_usize(&self) -> usize {
1363 /// Gets the "depth" of this universe in the universe tree. This
1364 /// is not really useful except for e.g. the `HashStable`
1366 pub fn depth(&self) -> u32 {
1371 /// When type checking, we use the `ParamEnv` to track
1372 /// details about the set of where-clauses that are in scope at this
1373 /// particular point.
1374 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1375 pub struct ParamEnv<'tcx> {
1376 /// Obligations that the caller must satisfy. This is basically
1377 /// the set of bounds on the in-scope type parameters, translated
1378 /// into Obligations, and elaborated and normalized.
1379 pub caller_bounds: &'tcx Slice<ty::Predicate<'tcx>>,
1381 /// Typically, this is `Reveal::UserFacing`, but during trans we
1382 /// want `Reveal::All` -- note that this is always paired with an
1383 /// empty environment. To get that, use `ParamEnv::reveal()`.
1384 pub reveal: traits::Reveal,
1386 /// What is the innermost universe we have created? Starts out as
1387 /// `UniverseIndex::root()` but grows from there as we enter
1388 /// universal quantifiers.
1390 /// NB: At present, we exclude the universal quantifiers on the
1391 /// item we are type-checking, and just consider those names as
1392 /// part of the root universe. So this would only get incremented
1393 /// when we enter into a higher-ranked (`for<..>`) type or trait
1395 pub universe: UniverseIndex,
1398 impl<'tcx> ParamEnv<'tcx> {
1399 /// Creates a suitable environment in which to perform trait
1400 /// queries on the given value. This will either be `self` *or*
1401 /// the empty environment, depending on whether `value` references
1402 /// type parameters that are in scope. (If it doesn't, then any
1403 /// judgements should be completely independent of the context,
1404 /// and hence we can safely use the empty environment so as to
1405 /// enable more sharing across functions.)
1407 /// NB: This is a mildly dubious thing to do, in that a function
1408 /// (or other environment) might have wacky where-clauses like
1409 /// `where Box<u32>: Copy`, which are clearly never
1410 /// satisfiable. The code will at present ignore these,
1411 /// effectively, when type-checking the body of said
1412 /// function. This preserves existing behavior in any
1413 /// case. --nmatsakis
1414 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1415 assert!(!value.needs_infer());
1416 if value.has_param_types() || value.has_self_ty() {
1423 param_env: ParamEnv::empty(self.reveal),
1430 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1431 pub struct ParamEnvAnd<'tcx, T> {
1432 pub param_env: ParamEnv<'tcx>,
1436 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1437 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1438 (self.param_env, self.value)
1442 impl<'gcx, T> HashStable<StableHashingContext<'gcx>> for ParamEnvAnd<'gcx, T>
1443 where T: HashStable<StableHashingContext<'gcx>>
1445 fn hash_stable<W: StableHasherResult>(&self,
1446 hcx: &mut StableHashingContext<'gcx>,
1447 hasher: &mut StableHasher<W>) {
1453 param_env.hash_stable(hcx, hasher);
1454 value.hash_stable(hcx, hasher);
1458 #[derive(Copy, Clone, Debug)]
1459 pub struct Destructor {
1460 /// The def-id of the destructor method
1465 pub struct AdtFlags: u32 {
1466 const NO_ADT_FLAGS = 0;
1467 const IS_ENUM = 1 << 0;
1468 const IS_PHANTOM_DATA = 1 << 1;
1469 const IS_FUNDAMENTAL = 1 << 2;
1470 const IS_UNION = 1 << 3;
1471 const IS_BOX = 1 << 4;
1472 /// Indicates whether this abstract data type will be expanded on in future (new
1473 /// fields/variants) and as such, whether downstream crates must match exhaustively on the
1474 /// fields/variants of this data type.
1476 /// See RFC 2008 (<https://github.com/rust-lang/rfcs/pull/2008>).
1477 const IS_NON_EXHAUSTIVE = 1 << 5;
1482 pub struct VariantDef {
1483 /// The variant's DefId. If this is a tuple-like struct,
1484 /// this is the DefId of the struct's ctor.
1486 pub name: Name, // struct's name if this is a struct
1487 pub discr: VariantDiscr,
1488 pub fields: Vec<FieldDef>,
1489 pub ctor_kind: CtorKind,
1492 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1493 pub enum VariantDiscr {
1494 /// Explicit value for this variant, i.e. `X = 123`.
1495 /// The `DefId` corresponds to the embedded constant.
1498 /// The previous variant's discriminant plus one.
1499 /// For efficiency reasons, the distance from the
1500 /// last `Explicit` discriminant is being stored,
1501 /// or `0` for the first variant, if it has none.
1506 pub struct FieldDef {
1509 pub vis: Visibility,
1512 /// The definition of an abstract data type - a struct or enum.
1514 /// These are all interned (by intern_adt_def) into the adt_defs
1518 pub variants: Vec<VariantDef>,
1520 pub repr: ReprOptions,
1523 impl PartialEq for AdtDef {
1524 // AdtDef are always interned and this is part of TyS equality
1526 fn eq(&self, other: &Self) -> bool { self as *const _ == other as *const _ }
1529 impl Eq for AdtDef {}
1531 impl Hash for AdtDef {
1533 fn hash<H: Hasher>(&self, s: &mut H) {
1534 (self as *const AdtDef).hash(s)
1538 impl<'tcx> serialize::UseSpecializedEncodable for &'tcx AdtDef {
1539 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1544 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx AdtDef {}
1547 impl<'gcx> HashStable<StableHashingContext<'gcx>> for AdtDef {
1548 fn hash_stable<W: StableHasherResult>(&self,
1549 hcx: &mut StableHashingContext<'gcx>,
1550 hasher: &mut StableHasher<W>) {
1552 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> =
1553 RefCell::new(FxHashMap());
1556 let hash: Fingerprint = CACHE.with(|cache| {
1557 let addr = self as *const AdtDef as usize;
1558 *cache.borrow_mut().entry(addr).or_insert_with(|| {
1566 let mut hasher = StableHasher::new();
1567 did.hash_stable(hcx, &mut hasher);
1568 variants.hash_stable(hcx, &mut hasher);
1569 flags.hash_stable(hcx, &mut hasher);
1570 repr.hash_stable(hcx, &mut hasher);
1576 hash.hash_stable(hcx, hasher);
1580 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
1581 pub enum AdtKind { Struct, Union, Enum }
1584 #[derive(RustcEncodable, RustcDecodable, Default)]
1585 pub struct ReprFlags: u8 {
1586 const IS_C = 1 << 0;
1587 const IS_PACKED = 1 << 1;
1588 const IS_SIMD = 1 << 2;
1589 const IS_TRANSPARENT = 1 << 3;
1590 // Internal only for now. If true, don't reorder fields.
1591 const IS_LINEAR = 1 << 4;
1593 // Any of these flags being set prevent field reordering optimisation.
1594 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
1595 ReprFlags::IS_PACKED.bits |
1596 ReprFlags::IS_SIMD.bits |
1597 ReprFlags::IS_LINEAR.bits;
1601 impl_stable_hash_for!(struct ReprFlags {
1607 /// Represents the repr options provided by the user,
1608 #[derive(Copy, Clone, Eq, PartialEq, RustcEncodable, RustcDecodable, Default)]
1609 pub struct ReprOptions {
1610 pub int: Option<attr::IntType>,
1612 pub flags: ReprFlags,
1615 impl_stable_hash_for!(struct ReprOptions {
1622 pub fn new(tcx: TyCtxt, did: DefId) -> ReprOptions {
1623 let mut flags = ReprFlags::empty();
1624 let mut size = None;
1625 let mut max_align = 0;
1626 for attr in tcx.get_attrs(did).iter() {
1627 for r in attr::find_repr_attrs(tcx.sess.diagnostic(), attr) {
1628 flags.insert(match r {
1629 attr::ReprC => ReprFlags::IS_C,
1630 attr::ReprPacked => ReprFlags::IS_PACKED,
1631 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1632 attr::ReprSimd => ReprFlags::IS_SIMD,
1633 attr::ReprInt(i) => {
1637 attr::ReprAlign(align) => {
1638 max_align = cmp::max(align, max_align);
1645 // This is here instead of layout because the choice must make it into metadata.
1646 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.item_path_str(did))) {
1647 flags.insert(ReprFlags::IS_LINEAR);
1649 ReprOptions { int: size, align: max_align, flags: flags }
1653 pub fn simd(&self) -> bool { self.flags.contains(ReprFlags::IS_SIMD) }
1655 pub fn c(&self) -> bool { self.flags.contains(ReprFlags::IS_C) }
1657 pub fn packed(&self) -> bool { self.flags.contains(ReprFlags::IS_PACKED) }
1659 pub fn transparent(&self) -> bool { self.flags.contains(ReprFlags::IS_TRANSPARENT) }
1661 pub fn linear(&self) -> bool { self.flags.contains(ReprFlags::IS_LINEAR) }
1663 pub fn discr_type(&self) -> attr::IntType {
1664 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1667 /// Returns true if this `#[repr()]` should inhabit "smart enum
1668 /// layout" optimizations, such as representing `Foo<&T>` as a
1670 pub fn inhibit_enum_layout_opt(&self) -> bool {
1671 self.c() || self.int.is_some()
1675 impl<'a, 'gcx, 'tcx> AdtDef {
1679 variants: Vec<VariantDef>,
1680 repr: ReprOptions) -> Self {
1681 let mut flags = AdtFlags::NO_ADT_FLAGS;
1682 let attrs = tcx.get_attrs(did);
1683 if attr::contains_name(&attrs, "fundamental") {
1684 flags = flags | AdtFlags::IS_FUNDAMENTAL;
1686 if Some(did) == tcx.lang_items().phantom_data() {
1687 flags = flags | AdtFlags::IS_PHANTOM_DATA;
1689 if Some(did) == tcx.lang_items().owned_box() {
1690 flags = flags | AdtFlags::IS_BOX;
1692 if tcx.has_attr(did, "non_exhaustive") {
1693 flags = flags | AdtFlags::IS_NON_EXHAUSTIVE;
1696 AdtKind::Enum => flags = flags | AdtFlags::IS_ENUM,
1697 AdtKind::Union => flags = flags | AdtFlags::IS_UNION,
1698 AdtKind::Struct => {}
1709 pub fn is_struct(&self) -> bool {
1710 !self.is_union() && !self.is_enum()
1714 pub fn is_union(&self) -> bool {
1715 self.flags.intersects(AdtFlags::IS_UNION)
1719 pub fn is_enum(&self) -> bool {
1720 self.flags.intersects(AdtFlags::IS_ENUM)
1724 pub fn is_non_exhaustive(&self) -> bool {
1725 self.flags.intersects(AdtFlags::IS_NON_EXHAUSTIVE)
1728 /// Returns the kind of the ADT - Struct or Enum.
1730 pub fn adt_kind(&self) -> AdtKind {
1733 } else if self.is_union() {
1740 pub fn descr(&self) -> &'static str {
1741 match self.adt_kind() {
1742 AdtKind::Struct => "struct",
1743 AdtKind::Union => "union",
1744 AdtKind::Enum => "enum",
1748 pub fn variant_descr(&self) -> &'static str {
1749 match self.adt_kind() {
1750 AdtKind::Struct => "struct",
1751 AdtKind::Union => "union",
1752 AdtKind::Enum => "variant",
1756 /// Returns whether this type is #[fundamental] for the purposes
1757 /// of coherence checking.
1759 pub fn is_fundamental(&self) -> bool {
1760 self.flags.intersects(AdtFlags::IS_FUNDAMENTAL)
1763 /// Returns true if this is PhantomData<T>.
1765 pub fn is_phantom_data(&self) -> bool {
1766 self.flags.intersects(AdtFlags::IS_PHANTOM_DATA)
1769 /// Returns true if this is Box<T>.
1771 pub fn is_box(&self) -> bool {
1772 self.flags.intersects(AdtFlags::IS_BOX)
1775 /// Returns whether this type has a destructor.
1776 pub fn has_dtor(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool {
1777 self.destructor(tcx).is_some()
1780 /// Asserts this is a struct or union and returns its unique variant.
1781 pub fn non_enum_variant(&self) -> &VariantDef {
1782 assert!(self.is_struct() || self.is_union());
1787 pub fn predicates(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> GenericPredicates<'gcx> {
1788 tcx.predicates_of(self.did)
1791 /// Returns an iterator over all fields contained
1794 pub fn all_fields<'s>(&'s self) -> impl Iterator<Item = &'s FieldDef> {
1795 self.variants.iter().flat_map(|v| v.fields.iter())
1798 pub fn is_payloadfree(&self) -> bool {
1799 !self.variants.is_empty() &&
1800 self.variants.iter().all(|v| v.fields.is_empty())
1803 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
1806 .find(|v| v.did == vid)
1807 .expect("variant_with_id: unknown variant")
1810 pub fn variant_index_with_id(&self, vid: DefId) -> usize {
1813 .position(|v| v.did == vid)
1814 .expect("variant_index_with_id: unknown variant")
1817 pub fn variant_of_def(&self, def: Def) -> &VariantDef {
1819 Def::Variant(vid) | Def::VariantCtor(vid, ..) => self.variant_with_id(vid),
1820 Def::Struct(..) | Def::StructCtor(..) | Def::Union(..) |
1821 Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => self.non_enum_variant(),
1822 _ => bug!("unexpected def {:?} in variant_of_def", def)
1827 pub fn discriminants(&'a self, tcx: TyCtxt<'a, 'gcx, 'tcx>)
1828 -> impl Iterator<Item=ConstInt> + 'a {
1829 let param_env = ParamEnv::empty(traits::Reveal::UserFacing);
1830 let repr_type = self.repr.discr_type();
1831 let initial = repr_type.initial_discriminant(tcx.global_tcx());
1832 let mut prev_discr = None::<ConstInt>;
1833 self.variants.iter().map(move |v| {
1834 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr());
1835 if let VariantDiscr::Explicit(expr_did) = v.discr {
1836 let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did);
1837 match tcx.const_eval(param_env.and((expr_did, substs))) {
1838 Ok(&ty::Const { val: ConstVal::Integral(v), .. }) => {
1842 if !expr_did.is_local() {
1843 span_bug!(tcx.def_span(expr_did),
1844 "variant discriminant evaluation succeeded \
1845 in its crate but failed locally: {:?}", err);
1850 prev_discr = Some(discr);
1856 /// Compute the discriminant value used by a specific variant.
1857 /// Unlike `discriminants`, this is (amortized) constant-time,
1858 /// only doing at most one query for evaluating an explicit
1859 /// discriminant (the last one before the requested variant),
1860 /// assuming there are no constant-evaluation errors there.
1861 pub fn discriminant_for_variant(&self,
1862 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1863 variant_index: usize)
1865 let param_env = ParamEnv::empty(traits::Reveal::UserFacing);
1866 let repr_type = self.repr.discr_type();
1867 let mut explicit_value = repr_type.initial_discriminant(tcx.global_tcx());
1868 let mut explicit_index = variant_index;
1870 match self.variants[explicit_index].discr {
1871 ty::VariantDiscr::Relative(0) => break,
1872 ty::VariantDiscr::Relative(distance) => {
1873 explicit_index -= distance;
1875 ty::VariantDiscr::Explicit(expr_did) => {
1876 let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did);
1877 match tcx.const_eval(param_env.and((expr_did, substs))) {
1878 Ok(&ty::Const { val: ConstVal::Integral(v), .. }) => {
1883 if !expr_did.is_local() {
1884 span_bug!(tcx.def_span(expr_did),
1885 "variant discriminant evaluation succeeded \
1886 in its crate but failed locally: {:?}", err);
1888 if explicit_index == 0 {
1891 explicit_index -= 1;
1897 let discr = explicit_value.to_u128_unchecked()
1898 .wrapping_add((variant_index - explicit_index) as u128);
1900 attr::UnsignedInt(ty) => {
1901 ConstInt::new_unsigned_truncating(discr, ty,
1902 tcx.sess.target.usize_ty)
1904 attr::SignedInt(ty) => {
1905 ConstInt::new_signed_truncating(discr as i128, ty,
1906 tcx.sess.target.isize_ty)
1911 pub fn destructor(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Destructor> {
1912 tcx.adt_destructor(self.did)
1915 /// Returns a list of types such that `Self: Sized` if and only
1916 /// if that type is Sized, or `TyErr` if this type is recursive.
1918 /// Oddly enough, checking that the sized-constraint is Sized is
1919 /// actually more expressive than checking all members:
1920 /// the Sized trait is inductive, so an associated type that references
1921 /// Self would prevent its containing ADT from being Sized.
1923 /// Due to normalization being eager, this applies even if
1924 /// the associated type is behind a pointer, e.g. issue #31299.
1925 pub fn sized_constraint(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> &'tcx [Ty<'tcx>] {
1926 match queries::adt_sized_constraint::try_get(tcx, DUMMY_SP, self.did) {
1929 debug!("adt_sized_constraint: {:?} is recursive", self);
1930 // This should be reported as an error by `check_representable`.
1932 // Consider the type as Sized in the meanwhile to avoid
1933 // further errors. Delay our `bug` diagnostic here to get
1934 // emitted later as well in case we accidentally otherwise don't
1937 tcx.intern_type_list(&[tcx.types.err])
1942 fn sized_constraint_for_ty(&self,
1943 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1946 let result = match ty.sty {
1947 TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) |
1948 TyRawPtr(..) | TyRef(..) | TyFnDef(..) | TyFnPtr(_) |
1949 TyArray(..) | TyClosure(..) | TyGenerator(..) | TyNever => {
1958 TyGeneratorWitness(..) => {
1959 // these are never sized - return the target type
1963 TyTuple(ref tys, _) => {
1966 Some(ty) => self.sized_constraint_for_ty(tcx, ty)
1970 TyAdt(adt, substs) => {
1972 let adt_tys = adt.sized_constraint(tcx);
1973 debug!("sized_constraint_for_ty({:?}) intermediate = {:?}",
1976 .map(|ty| ty.subst(tcx, substs))
1977 .flat_map(|ty| self.sized_constraint_for_ty(tcx, ty))
1981 TyProjection(..) | TyAnon(..) => {
1982 // must calculate explicitly.
1983 // FIXME: consider special-casing always-Sized projections
1988 // perf hack: if there is a `T: Sized` bound, then
1989 // we know that `T` is Sized and do not need to check
1992 let sized_trait = match tcx.lang_items().sized_trait() {
1994 _ => return vec![ty]
1996 let sized_predicate = Binder(TraitRef {
1997 def_id: sized_trait,
1998 substs: tcx.mk_substs_trait(ty, &[])
2000 let predicates = tcx.predicates_of(self.did).predicates;
2001 if predicates.into_iter().any(|p| p == sized_predicate) {
2009 bug!("unexpected type `{:?}` in sized_constraint_for_ty",
2013 debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result);
2018 impl<'a, 'gcx, 'tcx> VariantDef {
2020 pub fn find_field_named(&self, name: ast::Name) -> Option<&FieldDef> {
2021 self.index_of_field_named(name).map(|index| &self.fields[index])
2024 pub fn index_of_field_named(&self, name: ast::Name) -> Option<usize> {
2025 if let Some(index) = self.fields.iter().position(|f| f.name == name) {
2028 let mut ident = name.to_ident();
2029 while ident.ctxt != SyntaxContext::empty() {
2030 ident.ctxt.remove_mark();
2031 if let Some(field) = self.fields.iter().position(|f| f.name.to_ident() == ident) {
2039 pub fn field_named(&self, name: ast::Name) -> &FieldDef {
2040 self.find_field_named(name).unwrap()
2044 impl<'a, 'gcx, 'tcx> FieldDef {
2045 pub fn ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, subst: &Substs<'tcx>) -> Ty<'tcx> {
2046 tcx.type_of(self.did).subst(tcx, subst)
2050 /// Represents the various closure traits in the Rust language. This
2051 /// will determine the type of the environment (`self`, in the
2052 /// desuaring) argument that the closure expects.
2054 /// You can get the environment type of a closure using
2055 /// `tcx.closure_env_ty()`.
2056 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
2057 pub enum ClosureKind {
2058 // Warning: Ordering is significant here! The ordering is chosen
2059 // because the trait Fn is a subtrait of FnMut and so in turn, and
2060 // hence we order it so that Fn < FnMut < FnOnce.
2066 impl<'a, 'tcx> ClosureKind {
2067 // This is the initial value used when doing upvar inference.
2068 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2070 pub fn trait_did(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> DefId {
2072 ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem),
2073 ClosureKind::FnMut => {
2074 tcx.require_lang_item(FnMutTraitLangItem)
2076 ClosureKind::FnOnce => {
2077 tcx.require_lang_item(FnOnceTraitLangItem)
2082 /// True if this a type that impls this closure kind
2083 /// must also implement `other`.
2084 pub fn extends(self, other: ty::ClosureKind) -> bool {
2085 match (self, other) {
2086 (ClosureKind::Fn, ClosureKind::Fn) => true,
2087 (ClosureKind::Fn, ClosureKind::FnMut) => true,
2088 (ClosureKind::Fn, ClosureKind::FnOnce) => true,
2089 (ClosureKind::FnMut, ClosureKind::FnMut) => true,
2090 (ClosureKind::FnMut, ClosureKind::FnOnce) => true,
2091 (ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
2096 /// Returns the representative scalar type for this closure kind.
2097 /// See `TyS::to_opt_closure_kind` for more details.
2098 pub fn to_ty(self, tcx: TyCtxt<'_, '_, 'tcx>) -> Ty<'tcx> {
2100 ty::ClosureKind::Fn => tcx.types.i8,
2101 ty::ClosureKind::FnMut => tcx.types.i16,
2102 ty::ClosureKind::FnOnce => tcx.types.i32,
2107 impl<'tcx> TyS<'tcx> {
2108 /// Iterator that walks `self` and any types reachable from
2109 /// `self`, in depth-first order. Note that just walks the types
2110 /// that appear in `self`, it does not descend into the fields of
2111 /// structs or variants. For example:
2114 /// isize => { isize }
2115 /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
2116 /// [isize] => { [isize], isize }
2118 pub fn walk(&'tcx self) -> TypeWalker<'tcx> {
2119 TypeWalker::new(self)
2122 /// Iterator that walks the immediate children of `self`. Hence
2123 /// `Foo<Bar<i32>, u32>` yields the sequence `[Bar<i32>, u32]`
2124 /// (but not `i32`, like `walk`).
2125 pub fn walk_shallow(&'tcx self) -> AccIntoIter<walk::TypeWalkerArray<'tcx>> {
2126 walk::walk_shallow(self)
2129 /// Walks `ty` and any types appearing within `ty`, invoking the
2130 /// callback `f` on each type. If the callback returns false, then the
2131 /// children of the current type are ignored.
2133 /// Note: prefer `ty.walk()` where possible.
2134 pub fn maybe_walk<F>(&'tcx self, mut f: F)
2135 where F : FnMut(Ty<'tcx>) -> bool
2137 let mut walker = self.walk();
2138 while let Some(ty) = walker.next() {
2140 walker.skip_current_subtree();
2147 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2149 hir::MutMutable => MutBorrow,
2150 hir::MutImmutable => ImmBorrow,
2154 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2155 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2156 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2158 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2160 MutBorrow => hir::MutMutable,
2161 ImmBorrow => hir::MutImmutable,
2163 // We have no type corresponding to a unique imm borrow, so
2164 // use `&mut`. It gives all the capabilities of an `&uniq`
2165 // and hence is a safe "over approximation".
2166 UniqueImmBorrow => hir::MutMutable,
2170 pub fn to_user_str(&self) -> &'static str {
2172 MutBorrow => "mutable",
2173 ImmBorrow => "immutable",
2174 UniqueImmBorrow => "uniquely immutable",
2179 #[derive(Debug, Clone)]
2180 pub enum Attributes<'gcx> {
2181 Owned(Lrc<[ast::Attribute]>),
2182 Borrowed(&'gcx [ast::Attribute])
2185 impl<'gcx> ::std::ops::Deref for Attributes<'gcx> {
2186 type Target = [ast::Attribute];
2188 fn deref(&self) -> &[ast::Attribute] {
2190 &Attributes::Owned(ref data) => &data,
2191 &Attributes::Borrowed(data) => data
2196 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
2197 pub fn body_tables(self, body: hir::BodyId) -> &'gcx TypeckTables<'gcx> {
2198 self.typeck_tables_of(self.hir.body_owner_def_id(body))
2201 /// Returns an iterator of the def-ids for all body-owners in this
2202 /// crate. If you would prefer to iterate over the bodies
2203 /// themselves, you can do `self.hir.krate().body_ids.iter()`.
2204 pub fn body_owners(self) -> impl Iterator<Item = DefId> + 'a {
2208 .map(move |&body_id| self.hir.body_owner_def_id(body_id))
2211 pub fn expr_span(self, id: NodeId) -> Span {
2212 match self.hir.find(id) {
2213 Some(hir_map::NodeExpr(e)) => {
2217 bug!("Node id {} is not an expr: {:?}", id, f);
2220 bug!("Node id {} is not present in the node map", id);
2225 pub fn provided_trait_methods(self, id: DefId) -> Vec<AssociatedItem> {
2226 self.associated_items(id)
2227 .filter(|item| item.kind == AssociatedKind::Method && item.defaultness.has_value())
2231 pub fn trait_relevant_for_never(self, did: DefId) -> bool {
2232 self.associated_items(did).any(|item| {
2233 item.relevant_for_never()
2237 pub fn opt_associated_item(self, def_id: DefId) -> Option<AssociatedItem> {
2238 let is_associated_item = if let Some(node_id) = self.hir.as_local_node_id(def_id) {
2239 match self.hir.get(node_id) {
2240 hir_map::NodeTraitItem(_) | hir_map::NodeImplItem(_) => true,
2244 match self.describe_def(def_id).expect("no def for def-id") {
2245 Def::AssociatedConst(_) | Def::Method(_) | Def::AssociatedTy(_) => true,
2250 if is_associated_item {
2251 Some(self.associated_item(def_id))
2257 fn associated_item_from_trait_item_ref(self,
2258 parent_def_id: DefId,
2259 parent_vis: &hir::Visibility,
2260 trait_item_ref: &hir::TraitItemRef)
2262 let def_id = self.hir.local_def_id(trait_item_ref.id.node_id);
2263 let (kind, has_self) = match trait_item_ref.kind {
2264 hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false),
2265 hir::AssociatedItemKind::Method { has_self } => {
2266 (ty::AssociatedKind::Method, has_self)
2268 hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false),
2272 name: trait_item_ref.name,
2274 // Visibility of trait items is inherited from their traits.
2275 vis: Visibility::from_hir(parent_vis, trait_item_ref.id.node_id, self),
2276 defaultness: trait_item_ref.defaultness,
2278 container: TraitContainer(parent_def_id),
2279 method_has_self_argument: has_self
2283 fn associated_item_from_impl_item_ref(self,
2284 parent_def_id: DefId,
2285 impl_item_ref: &hir::ImplItemRef)
2287 let def_id = self.hir.local_def_id(impl_item_ref.id.node_id);
2288 let (kind, has_self) = match impl_item_ref.kind {
2289 hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false),
2290 hir::AssociatedItemKind::Method { has_self } => {
2291 (ty::AssociatedKind::Method, has_self)
2293 hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false),
2296 ty::AssociatedItem {
2297 name: impl_item_ref.name,
2299 // Visibility of trait impl items doesn't matter.
2300 vis: ty::Visibility::from_hir(&impl_item_ref.vis, impl_item_ref.id.node_id, self),
2301 defaultness: impl_item_ref.defaultness,
2303 container: ImplContainer(parent_def_id),
2304 method_has_self_argument: has_self
2308 #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
2309 pub fn associated_items(self, def_id: DefId)
2310 -> impl Iterator<Item = ty::AssociatedItem> + 'a {
2311 let def_ids = self.associated_item_def_ids(def_id);
2312 (0..def_ids.len()).map(move |i| self.associated_item(def_ids[i]))
2315 /// Returns true if the impls are the same polarity and are implementing
2316 /// a trait which contains no items
2317 pub fn impls_are_allowed_to_overlap(self, def_id1: DefId, def_id2: DefId) -> bool {
2318 if !self.features().overlapping_marker_traits {
2321 let trait1_is_empty = self.impl_trait_ref(def_id1)
2322 .map_or(false, |trait_ref| {
2323 self.associated_item_def_ids(trait_ref.def_id).is_empty()
2325 let trait2_is_empty = self.impl_trait_ref(def_id2)
2326 .map_or(false, |trait_ref| {
2327 self.associated_item_def_ids(trait_ref.def_id).is_empty()
2329 self.impl_polarity(def_id1) == self.impl_polarity(def_id2)
2334 // Returns `ty::VariantDef` if `def` refers to a struct,
2335 // or variant or their constructors, panics otherwise.
2336 pub fn expect_variant_def(self, def: Def) -> &'tcx VariantDef {
2338 Def::Variant(did) | Def::VariantCtor(did, ..) => {
2339 let enum_did = self.parent_def_id(did).unwrap();
2340 self.adt_def(enum_did).variant_with_id(did)
2342 Def::Struct(did) | Def::Union(did) => {
2343 self.adt_def(did).non_enum_variant()
2345 Def::StructCtor(ctor_did, ..) => {
2346 let did = self.parent_def_id(ctor_did).expect("struct ctor has no parent");
2347 self.adt_def(did).non_enum_variant()
2349 _ => bug!("expect_variant_def used with unexpected def {:?}", def)
2353 /// Given a `VariantDef`, returns the def-id of the `AdtDef` of which it is a part.
2354 pub fn adt_def_id_of_variant(self, variant_def: &'tcx VariantDef) -> DefId {
2355 let def_key = self.def_key(variant_def.did);
2356 match def_key.disambiguated_data.data {
2357 // for enum variants and tuple structs, the def-id of the ADT itself
2358 // is the *parent* of the variant
2359 DefPathData::EnumVariant(..) | DefPathData::StructCtor =>
2360 DefId { krate: variant_def.did.krate, index: def_key.parent.unwrap() },
2362 // otherwise, for structs and unions, they share a def-id
2363 _ => variant_def.did,
2367 pub fn item_name(self, id: DefId) -> InternedString {
2368 if id.index == CRATE_DEF_INDEX {
2369 self.original_crate_name(id.krate).as_str()
2371 let def_key = self.def_key(id);
2372 // The name of a StructCtor is that of its struct parent.
2373 if let hir_map::DefPathData::StructCtor = def_key.disambiguated_data.data {
2374 self.item_name(DefId {
2376 index: def_key.parent.unwrap()
2379 def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
2380 bug!("item_name: no name for {:?}", self.def_path(id));
2386 /// Return the possibly-auto-generated MIR of a (DefId, Subst) pair.
2387 pub fn instance_mir(self, instance: ty::InstanceDef<'gcx>)
2391 ty::InstanceDef::Item(did) => {
2392 self.optimized_mir(did)
2394 ty::InstanceDef::Intrinsic(..) |
2395 ty::InstanceDef::FnPtrShim(..) |
2396 ty::InstanceDef::Virtual(..) |
2397 ty::InstanceDef::ClosureOnceShim { .. } |
2398 ty::InstanceDef::DropGlue(..) |
2399 ty::InstanceDef::CloneShim(..) => {
2400 self.mir_shims(instance)
2405 /// Given the DefId of an item, returns its MIR, borrowed immutably.
2406 /// Returns None if there is no MIR for the DefId
2407 pub fn maybe_optimized_mir(self, did: DefId) -> Option<&'gcx Mir<'gcx>> {
2408 if self.is_mir_available(did) {
2409 Some(self.optimized_mir(did))
2415 /// Get the attributes of a definition.
2416 pub fn get_attrs(self, did: DefId) -> Attributes<'gcx> {
2417 if let Some(id) = self.hir.as_local_node_id(did) {
2418 Attributes::Borrowed(self.hir.attrs(id))
2420 Attributes::Owned(self.item_attrs(did))
2424 /// Determine whether an item is annotated with an attribute
2425 pub fn has_attr(self, did: DefId, attr: &str) -> bool {
2426 attr::contains_name(&self.get_attrs(did), attr)
2429 /// Returns true if this is an `auto trait`.
2430 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2431 self.trait_def(trait_def_id).has_auto_impl
2434 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
2435 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
2438 /// Given the def_id of an impl, return the def_id of the trait it implements.
2439 /// If it implements no trait, return `None`.
2440 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2441 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2444 /// If the given def ID describes a method belonging to an impl, return the
2445 /// ID of the impl that the method belongs to. Otherwise, return `None`.
2446 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2447 let item = if def_id.krate != LOCAL_CRATE {
2448 if let Some(Def::Method(_)) = self.describe_def(def_id) {
2449 Some(self.associated_item(def_id))
2454 self.opt_associated_item(def_id)
2458 Some(trait_item) => {
2459 match trait_item.container {
2460 TraitContainer(_) => None,
2461 ImplContainer(def_id) => Some(def_id),
2468 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2469 /// with the name of the crate containing the impl.
2470 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2471 if impl_did.is_local() {
2472 let node_id = self.hir.as_local_node_id(impl_did).unwrap();
2473 Ok(self.hir.span(node_id))
2475 Err(self.crate_name(impl_did.krate))
2479 // Hygienically compare a use-site name (`use_name`) for a field or an associated item with its
2480 // supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2481 // definition's parent/scope to perform comparison.
2482 pub fn hygienic_eq(self, use_name: Name, def_name: Name, def_parent_def_id: DefId) -> bool {
2483 self.adjust(use_name, def_parent_def_id, DUMMY_NODE_ID).0 == def_name.to_ident()
2486 pub fn adjust(self, name: Name, scope: DefId, block: NodeId) -> (Ident, DefId) {
2487 self.adjust_ident(name.to_ident(), scope, block)
2490 pub fn adjust_ident(self, mut ident: Ident, scope: DefId, block: NodeId) -> (Ident, DefId) {
2491 let expansion = match scope.krate {
2492 LOCAL_CRATE => self.hir.definitions().expansion(scope.index),
2495 let scope = match ident.ctxt.adjust(expansion) {
2496 Some(macro_def) => self.hir.definitions().macro_def_scope(macro_def),
2497 None if block == DUMMY_NODE_ID => DefId::local(CRATE_DEF_INDEX), // Dummy DefId
2498 None => self.hir.get_module_parent(block),
2504 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
2505 pub fn with_freevars<T, F>(self, fid: NodeId, f: F) -> T where
2506 F: FnOnce(&[hir::Freevar]) -> T,
2508 let def_id = self.hir.local_def_id(fid);
2509 match self.freevars(def_id) {
2516 fn associated_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId)
2519 let id = tcx.hir.as_local_node_id(def_id).unwrap();
2520 let parent_id = tcx.hir.get_parent(id);
2521 let parent_def_id = tcx.hir.local_def_id(parent_id);
2522 let parent_item = tcx.hir.expect_item(parent_id);
2523 match parent_item.node {
2524 hir::ItemImpl(.., ref impl_item_refs) => {
2525 if let Some(impl_item_ref) = impl_item_refs.iter().find(|i| i.id.node_id == id) {
2526 let assoc_item = tcx.associated_item_from_impl_item_ref(parent_def_id,
2528 debug_assert_eq!(assoc_item.def_id, def_id);
2533 hir::ItemTrait(.., ref trait_item_refs) => {
2534 if let Some(trait_item_ref) = trait_item_refs.iter().find(|i| i.id.node_id == id) {
2535 let assoc_item = tcx.associated_item_from_trait_item_ref(parent_def_id,
2538 debug_assert_eq!(assoc_item.def_id, def_id);
2546 span_bug!(parent_item.span,
2547 "unexpected parent of trait or impl item or item not found: {:?}",
2551 /// Calculates the Sized-constraint.
2553 /// In fact, there are only a few options for the types in the constraint:
2554 /// - an obviously-unsized type
2555 /// - a type parameter or projection whose Sizedness can't be known
2556 /// - a tuple of type parameters or projections, if there are multiple
2558 /// - a TyError, if a type contained itself. The representability
2559 /// check should catch this case.
2560 fn adt_sized_constraint<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2562 -> &'tcx [Ty<'tcx>] {
2563 let def = tcx.adt_def(def_id);
2565 let result = tcx.intern_type_list(&def.variants.iter().flat_map(|v| {
2568 def.sized_constraint_for_ty(tcx, tcx.type_of(f.did))
2569 }).collect::<Vec<_>>());
2571 debug!("adt_sized_constraint: {:?} => {:?}", def, result);
2576 /// Calculates the dtorck constraint for a type.
2577 fn adt_dtorck_constraint<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2579 -> DtorckConstraint<'tcx> {
2580 let def = tcx.adt_def(def_id);
2581 let span = tcx.def_span(def_id);
2582 debug!("dtorck_constraint: {:?}", def);
2584 if def.is_phantom_data() {
2585 let result = DtorckConstraint {
2588 tcx.mk_param_from_def(&tcx.generics_of(def_id).types[0])
2591 debug!("dtorck_constraint: {:?} => {:?}", def, result);
2595 let mut result = def.all_fields()
2596 .map(|field| tcx.type_of(field.did))
2597 .map(|fty| tcx.dtorck_constraint_for_ty(span, fty, 0, fty))
2598 .collect::<Result<DtorckConstraint, ErrorReported>>()
2599 .unwrap_or(DtorckConstraint::empty());
2600 result.outlives.extend(tcx.destructor_constraints(def));
2603 debug!("dtorck_constraint: {:?} => {:?}", def, result);
2608 fn associated_item_def_ids<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2610 -> Lrc<Vec<DefId>> {
2611 let id = tcx.hir.as_local_node_id(def_id).unwrap();
2612 let item = tcx.hir.expect_item(id);
2613 let vec: Vec<_> = match item.node {
2614 hir::ItemTrait(.., ref trait_item_refs) => {
2615 trait_item_refs.iter()
2616 .map(|trait_item_ref| trait_item_ref.id)
2617 .map(|id| tcx.hir.local_def_id(id.node_id))
2620 hir::ItemImpl(.., ref impl_item_refs) => {
2621 impl_item_refs.iter()
2622 .map(|impl_item_ref| impl_item_ref.id)
2623 .map(|id| tcx.hir.local_def_id(id.node_id))
2626 hir::ItemTraitAlias(..) => vec![],
2627 _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait")
2632 fn def_span<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Span {
2633 tcx.hir.span_if_local(def_id).unwrap()
2636 /// If the given def ID describes an item belonging to a trait,
2637 /// return the ID of the trait that the trait item belongs to.
2638 /// Otherwise, return `None`.
2639 fn trait_of_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Option<DefId> {
2640 tcx.opt_associated_item(def_id)
2641 .and_then(|associated_item| {
2642 match associated_item.container {
2643 TraitContainer(def_id) => Some(def_id),
2644 ImplContainer(_) => None
2649 /// See `ParamEnv` struct def'n for details.
2650 fn param_env<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2653 // Compute the bounds on Self and the type parameters.
2655 let bounds = tcx.predicates_of(def_id).instantiate_identity(tcx);
2656 let predicates = bounds.predicates;
2658 // Finally, we have to normalize the bounds in the environment, in
2659 // case they contain any associated type projections. This process
2660 // can yield errors if the put in illegal associated types, like
2661 // `<i32 as Foo>::Bar` where `i32` does not implement `Foo`. We
2662 // report these errors right here; this doesn't actually feel
2663 // right to me, because constructing the environment feels like a
2664 // kind of a "idempotent" action, but I'm not sure where would be
2665 // a better place. In practice, we construct environments for
2666 // every fn once during type checking, and we'll abort if there
2667 // are any errors at that point, so after type checking you can be
2668 // sure that this will succeed without errors anyway.
2670 let unnormalized_env = ty::ParamEnv::new(tcx.intern_predicates(&predicates),
2671 traits::Reveal::UserFacing,
2672 ty::UniverseIndex::ROOT);
2674 let body_id = tcx.hir.as_local_node_id(def_id).map_or(DUMMY_NODE_ID, |id| {
2675 tcx.hir.maybe_body_owned_by(id).map_or(id, |body| body.node_id)
2677 let cause = traits::ObligationCause::misc(tcx.def_span(def_id), body_id);
2678 traits::normalize_param_env_or_error(tcx, def_id, unnormalized_env, cause)
2681 fn crate_disambiguator<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2682 crate_num: CrateNum) -> CrateDisambiguator {
2683 assert_eq!(crate_num, LOCAL_CRATE);
2684 tcx.sess.local_crate_disambiguator()
2687 fn original_crate_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2688 crate_num: CrateNum) -> Symbol {
2689 assert_eq!(crate_num, LOCAL_CRATE);
2690 tcx.crate_name.clone()
2693 fn crate_hash<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2694 crate_num: CrateNum)
2696 assert_eq!(crate_num, LOCAL_CRATE);
2700 fn instance_def_size_estimate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2701 instance_def: InstanceDef<'tcx>)
2703 match instance_def {
2704 InstanceDef::Item(..) |
2705 InstanceDef::DropGlue(..) => {
2706 let mir = tcx.instance_mir(instance_def);
2707 mir.basic_blocks().iter().map(|bb| bb.statements.len()).sum()
2709 // Estimate the size of other compiler-generated shims to be 1.
2714 pub fn provide(providers: &mut ty::maps::Providers) {
2715 context::provide(providers);
2716 erase_regions::provide(providers);
2717 layout::provide(providers);
2718 util::provide(providers);
2719 *providers = ty::maps::Providers {
2721 associated_item_def_ids,
2722 adt_sized_constraint,
2723 adt_dtorck_constraint,
2727 crate_disambiguator,
2728 original_crate_name,
2730 trait_impls_of: trait_def::trait_impls_of_provider,
2731 instance_def_size_estimate,
2736 /// A map for the local crate mapping each type to a vector of its
2737 /// inherent impls. This is not meant to be used outside of coherence;
2738 /// rather, you should request the vector for a specific type via
2739 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2740 /// (constructing this map requires touching the entire crate).
2741 #[derive(Clone, Debug)]
2742 pub struct CrateInherentImpls {
2743 pub inherent_impls: DefIdMap<Lrc<Vec<DefId>>>,
2746 /// A set of constraints that need to be satisfied in order for
2747 /// a type to be valid for destruction.
2748 #[derive(Clone, Debug)]
2749 pub struct DtorckConstraint<'tcx> {
2750 /// Types that are required to be alive in order for this
2751 /// type to be valid for destruction.
2752 pub outlives: Vec<ty::subst::Kind<'tcx>>,
2753 /// Types that could not be resolved: projections and params.
2754 pub dtorck_types: Vec<Ty<'tcx>>,
2757 impl<'tcx> FromIterator<DtorckConstraint<'tcx>> for DtorckConstraint<'tcx>
2759 fn from_iter<I: IntoIterator<Item=DtorckConstraint<'tcx>>>(iter: I) -> Self {
2760 let mut result = Self::empty();
2762 for constraint in iter {
2763 result.outlives.extend(constraint.outlives);
2764 result.dtorck_types.extend(constraint.dtorck_types);
2772 impl<'tcx> DtorckConstraint<'tcx> {
2773 fn empty() -> DtorckConstraint<'tcx> {
2776 dtorck_types: vec![]
2780 fn dedup<'a>(&mut self) {
2781 let mut outlives = FxHashSet();
2782 let mut dtorck_types = FxHashSet();
2784 self.outlives.retain(|&val| outlives.replace(val).is_none());
2785 self.dtorck_types.retain(|&val| dtorck_types.replace(val).is_none());
2789 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable)]
2790 pub struct SymbolName {
2791 // FIXME: we don't rely on interning or equality here - better have
2792 // this be a `&'tcx str`.
2793 pub name: InternedString
2796 impl_stable_hash_for!(struct self::SymbolName {
2801 pub fn new(name: &str) -> SymbolName {
2803 name: Symbol::intern(name).as_str()
2808 impl Deref for SymbolName {
2811 fn deref(&self) -> &str { &self.name }
2814 impl fmt::Display for SymbolName {
2815 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2816 fmt::Display::fmt(&self.name, fmt)
2820 impl fmt::Debug for SymbolName {
2821 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2822 fmt::Display::fmt(&self.name, fmt)