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::interpret::{GlobalId, Value, PrimVal};
30 use mir::GeneratorLayout;
31 use session::CrateDisambiguator;
32 use traits::{self, Reveal};
34 use ty::subst::{Subst, Substs};
35 use ty::util::{IntTypeExt, Discr};
36 use ty::walk::TypeWalker;
37 use util::captures::Captures;
38 use util::nodemap::{NodeSet, DefIdMap, FxHashMap};
40 use serialize::{self, Encodable, Encoder};
41 use std::cell::RefCell;
44 use std::hash::{Hash, Hasher};
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};
56 use rustc_data_structures::accumulate_vec::IntoIter as AccIntoIter;
57 use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
62 pub use self::sty::{Binder, CanonicalVar, DebruijnIndex};
63 pub use self::sty::{FnSig, GenSig, PolyFnSig, PolyGenSig};
64 pub use self::sty::{InferTy, ParamTy, ProjectionTy, ExistentialPredicate};
65 pub use self::sty::{ClosureSubsts, GeneratorInterior, TypeAndMut};
66 pub use self::sty::{TraitRef, TypeVariants, PolyTraitRef};
67 pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
68 pub use self::sty::{ExistentialProjection, PolyExistentialProjection, Const};
69 pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
70 pub use self::sty::RegionKind;
71 pub use self::sty::{TyVid, IntVid, FloatVid, RegionVid};
72 pub use self::sty::BoundRegion::*;
73 pub use self::sty::InferTy::*;
74 pub use self::sty::RegionKind::*;
75 pub use self::sty::TypeVariants::*;
77 pub use self::binding::BindingMode;
78 pub use self::binding::BindingMode::*;
80 pub use self::context::{TyCtxt, GlobalArenas, AllArenas, tls, keep_local};
81 pub use self::context::{Lift, TypeckTables, InterpretInterner};
83 pub use self::instance::{Instance, InstanceDef};
85 pub use self::trait_def::TraitDef;
87 pub use self::maps::queries;
98 pub mod inhabitedness;
115 mod structural_impls;
120 /// The complete set of all analyses described in this module. This is
121 /// produced by the driver and fed to trans and later passes.
123 /// NB: These contents are being migrated into queries using the
124 /// *on-demand* infrastructure.
126 pub struct CrateAnalysis {
127 pub access_levels: Lrc<AccessLevels>,
129 pub glob_map: Option<hir::GlobMap>,
133 pub struct Resolutions {
134 pub freevars: FreevarMap,
135 pub trait_map: TraitMap,
136 pub maybe_unused_trait_imports: NodeSet,
137 pub maybe_unused_extern_crates: Vec<(NodeId, Span)>,
138 pub export_map: ExportMap,
141 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
142 pub enum AssociatedItemContainer {
143 TraitContainer(DefId),
144 ImplContainer(DefId),
147 impl AssociatedItemContainer {
148 /// Asserts that this is the def-id of an associated item declared
149 /// in a trait, and returns the trait def-id.
150 pub fn assert_trait(&self) -> DefId {
152 TraitContainer(id) => id,
153 _ => bug!("associated item has wrong container type: {:?}", self)
157 pub fn id(&self) -> DefId {
159 TraitContainer(id) => id,
160 ImplContainer(id) => id,
165 /// The "header" of an impl is everything outside the body: a Self type, a trait
166 /// ref (in the case of a trait impl), and a set of predicates (from the
167 /// bounds/where clauses).
168 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
169 pub struct ImplHeader<'tcx> {
170 pub impl_def_id: DefId,
171 pub self_ty: Ty<'tcx>,
172 pub trait_ref: Option<TraitRef<'tcx>>,
173 pub predicates: Vec<Predicate<'tcx>>,
176 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
177 pub struct AssociatedItem {
180 pub kind: AssociatedKind,
182 pub defaultness: hir::Defaultness,
183 pub container: AssociatedItemContainer,
185 /// Whether this is a method with an explicit self
186 /// as its first argument, allowing method calls.
187 pub method_has_self_argument: bool,
190 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash, RustcEncodable, RustcDecodable)]
191 pub enum AssociatedKind {
197 impl AssociatedItem {
198 pub fn def(&self) -> Def {
200 AssociatedKind::Const => Def::AssociatedConst(self.def_id),
201 AssociatedKind::Method => Def::Method(self.def_id),
202 AssociatedKind::Type => Def::AssociatedTy(self.def_id),
206 /// Tests whether the associated item admits a non-trivial implementation
208 pub fn relevant_for_never<'tcx>(&self) -> bool {
210 AssociatedKind::Const => true,
211 AssociatedKind::Type => true,
212 // FIXME(canndrew): Be more thorough here, check if any argument is uninhabited.
213 AssociatedKind::Method => !self.method_has_self_argument,
217 pub fn signature<'a, 'tcx>(&self, tcx: &TyCtxt<'a, 'tcx, 'tcx>) -> String {
219 ty::AssociatedKind::Method => {
220 // We skip the binder here because the binder would deanonymize all
221 // late-bound regions, and we don't want method signatures to show up
222 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
223 // regions just fine, showing `fn(&MyType)`.
224 format!("{}", tcx.fn_sig(self.def_id).skip_binder())
226 ty::AssociatedKind::Type => format!("type {};", self.name.to_string()),
227 ty::AssociatedKind::Const => {
228 format!("const {}: {:?};", self.name.to_string(), tcx.type_of(self.def_id))
234 #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable)]
235 pub enum Visibility {
236 /// Visible everywhere (including in other crates).
238 /// Visible only in the given crate-local module.
240 /// Not visible anywhere in the local crate. This is the visibility of private external items.
244 pub trait DefIdTree: Copy {
245 fn parent(self, id: DefId) -> Option<DefId>;
247 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
248 if descendant.krate != ancestor.krate {
252 while descendant != ancestor {
253 match self.parent(descendant) {
254 Some(parent) => descendant = parent,
255 None => return false,
262 impl<'a, 'gcx, 'tcx> DefIdTree for TyCtxt<'a, 'gcx, 'tcx> {
263 fn parent(self, id: DefId) -> Option<DefId> {
264 self.def_key(id).parent.map(|index| DefId { index: index, ..id })
269 pub fn from_hir(visibility: &hir::Visibility, id: NodeId, tcx: TyCtxt) -> Self {
271 hir::Public => Visibility::Public,
272 hir::Visibility::Crate => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
273 hir::Visibility::Restricted { ref path, .. } => match path.def {
274 // If there is no resolution, `resolve` will have already reported an error, so
275 // assume that the visibility is public to avoid reporting more privacy errors.
276 Def::Err => Visibility::Public,
277 def => Visibility::Restricted(def.def_id()),
280 Visibility::Restricted(tcx.hir.get_module_parent(id))
285 /// Returns true if an item with this visibility is accessible from the given block.
286 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
287 let restriction = match self {
288 // Public items are visible everywhere.
289 Visibility::Public => return true,
290 // Private items from other crates are visible nowhere.
291 Visibility::Invisible => return false,
292 // Restricted items are visible in an arbitrary local module.
293 Visibility::Restricted(other) if other.krate != module.krate => return false,
294 Visibility::Restricted(module) => module,
297 tree.is_descendant_of(module, restriction)
300 /// Returns true if this visibility is at least as accessible as the given visibility
301 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
302 let vis_restriction = match vis {
303 Visibility::Public => return self == Visibility::Public,
304 Visibility::Invisible => return true,
305 Visibility::Restricted(module) => module,
308 self.is_accessible_from(vis_restriction, tree)
311 // Returns true if this item is visible anywhere in the local crate.
312 pub fn is_visible_locally(self) -> bool {
314 Visibility::Public => true,
315 Visibility::Restricted(def_id) => def_id.is_local(),
316 Visibility::Invisible => false,
321 #[derive(Clone, PartialEq, RustcDecodable, RustcEncodable, Copy)]
323 Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
324 Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
325 Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
326 Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
329 /// The crate variances map is computed during typeck and contains the
330 /// variance of every item in the local crate. You should not use it
331 /// directly, because to do so will make your pass dependent on the
332 /// HIR of every item in the local crate. Instead, use
333 /// `tcx.variances_of()` to get the variance for a *particular*
335 pub struct CrateVariancesMap {
336 /// For each item with generics, maps to a vector of the variance
337 /// of its generics. If an item has no generics, it will have no
339 pub variances: FxHashMap<DefId, Lrc<Vec<ty::Variance>>>,
341 /// An empty vector, useful for cloning.
342 pub empty_variance: Lrc<Vec<ty::Variance>>,
346 /// `a.xform(b)` combines the variance of a context with the
347 /// variance of a type with the following meaning. If we are in a
348 /// context with variance `a`, and we encounter a type argument in
349 /// a position with variance `b`, then `a.xform(b)` is the new
350 /// variance with which the argument appears.
356 /// Here, the "ambient" variance starts as covariant. `*mut T` is
357 /// invariant with respect to `T`, so the variance in which the
358 /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which
359 /// yields `Invariant`. Now, the type `Vec<T>` is covariant with
360 /// respect to its type argument `T`, and hence the variance of
361 /// the `i32` here is `Invariant.xform(Covariant)`, which results
362 /// (again) in `Invariant`.
366 /// fn(*const Vec<i32>, *mut Vec<i32)
368 /// The ambient variance is covariant. A `fn` type is
369 /// contravariant with respect to its parameters, so the variance
370 /// within which both pointer types appear is
371 /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const
372 /// T` is covariant with respect to `T`, so the variance within
373 /// which the first `Vec<i32>` appears is
374 /// `Contravariant.xform(Covariant)` or `Contravariant`. The same
375 /// is true for its `i32` argument. In the `*mut T` case, the
376 /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`,
377 /// and hence the outermost type is `Invariant` with respect to
378 /// `Vec<i32>` (and its `i32` argument).
380 /// Source: Figure 1 of "Taming the Wildcards:
381 /// Combining Definition- and Use-Site Variance" published in PLDI'11.
382 pub fn xform(self, v: ty::Variance) -> ty::Variance {
384 // Figure 1, column 1.
385 (ty::Covariant, ty::Covariant) => ty::Covariant,
386 (ty::Covariant, ty::Contravariant) => ty::Contravariant,
387 (ty::Covariant, ty::Invariant) => ty::Invariant,
388 (ty::Covariant, ty::Bivariant) => ty::Bivariant,
390 // Figure 1, column 2.
391 (ty::Contravariant, ty::Covariant) => ty::Contravariant,
392 (ty::Contravariant, ty::Contravariant) => ty::Covariant,
393 (ty::Contravariant, ty::Invariant) => ty::Invariant,
394 (ty::Contravariant, ty::Bivariant) => ty::Bivariant,
396 // Figure 1, column 3.
397 (ty::Invariant, _) => ty::Invariant,
399 // Figure 1, column 4.
400 (ty::Bivariant, _) => ty::Bivariant,
405 // Contains information needed to resolve types and (in the future) look up
406 // the types of AST nodes.
407 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
408 pub struct CReaderCacheKey {
413 // Flags that we track on types. These flags are propagated upwards
414 // through the type during type construction, so that we can quickly
415 // check whether the type has various kinds of types in it without
416 // recursing over the type itself.
418 pub struct TypeFlags: u32 {
419 const HAS_PARAMS = 1 << 0;
420 const HAS_SELF = 1 << 1;
421 const HAS_TY_INFER = 1 << 2;
422 const HAS_RE_INFER = 1 << 3;
423 const HAS_RE_SKOL = 1 << 4;
425 /// Does this have any `ReEarlyBound` regions? Used to
426 /// determine whether substitition is required, since those
427 /// represent regions that are bound in a `ty::Generics` and
428 /// hence may be substituted.
429 const HAS_RE_EARLY_BOUND = 1 << 5;
431 /// Does this have any region that "appears free" in the type?
432 /// Basically anything but `ReLateBound` and `ReErased`.
433 const HAS_FREE_REGIONS = 1 << 6;
435 /// Is an error type reachable?
436 const HAS_TY_ERR = 1 << 7;
437 const HAS_PROJECTION = 1 << 8;
439 // FIXME: Rename this to the actual property since it's used for generators too
440 const HAS_TY_CLOSURE = 1 << 9;
442 // true if there are "names" of types and regions and so forth
443 // that are local to a particular fn
444 const HAS_LOCAL_NAMES = 1 << 10;
446 // Present if the type belongs in a local type context.
447 // Only set for TyInfer other than Fresh.
448 const KEEP_IN_LOCAL_TCX = 1 << 11;
450 // Is there a projection that does not involve a bound region?
451 // Currently we can't normalize projections w/ bound regions.
452 const HAS_NORMALIZABLE_PROJECTION = 1 << 12;
454 // Set if this includes a "canonical" type or region var --
455 // ought to be true only for the results of canonicalization.
456 const HAS_CANONICAL_VARS = 1 << 13;
458 const NEEDS_SUBST = TypeFlags::HAS_PARAMS.bits |
459 TypeFlags::HAS_SELF.bits |
460 TypeFlags::HAS_RE_EARLY_BOUND.bits;
462 // Flags representing the nominal content of a type,
463 // computed by FlagsComputation. If you add a new nominal
464 // flag, it should be added here too.
465 const NOMINAL_FLAGS = TypeFlags::HAS_PARAMS.bits |
466 TypeFlags::HAS_SELF.bits |
467 TypeFlags::HAS_TY_INFER.bits |
468 TypeFlags::HAS_RE_INFER.bits |
469 TypeFlags::HAS_RE_SKOL.bits |
470 TypeFlags::HAS_RE_EARLY_BOUND.bits |
471 TypeFlags::HAS_FREE_REGIONS.bits |
472 TypeFlags::HAS_TY_ERR.bits |
473 TypeFlags::HAS_PROJECTION.bits |
474 TypeFlags::HAS_TY_CLOSURE.bits |
475 TypeFlags::HAS_LOCAL_NAMES.bits |
476 TypeFlags::KEEP_IN_LOCAL_TCX.bits |
477 TypeFlags::HAS_CANONICAL_VARS.bits;
481 pub struct TyS<'tcx> {
482 pub sty: TypeVariants<'tcx>,
483 pub flags: TypeFlags,
485 // the maximal depth of any bound regions appearing in this type.
489 impl<'tcx> PartialEq for TyS<'tcx> {
491 fn eq(&self, other: &TyS<'tcx>) -> bool {
492 // (self as *const _) == (other as *const _)
493 (self as *const TyS<'tcx>) == (other as *const TyS<'tcx>)
496 impl<'tcx> Eq for TyS<'tcx> {}
498 impl<'tcx> Hash for TyS<'tcx> {
499 fn hash<H: Hasher>(&self, s: &mut H) {
500 (self as *const TyS).hash(s)
504 impl<'tcx> TyS<'tcx> {
505 pub fn is_primitive_ty(&self) -> bool {
507 TypeVariants::TyBool |
508 TypeVariants::TyChar |
509 TypeVariants::TyInt(_) |
510 TypeVariants::TyUint(_) |
511 TypeVariants::TyFloat(_) |
512 TypeVariants::TyInfer(InferTy::IntVar(_)) |
513 TypeVariants::TyInfer(InferTy::FloatVar(_)) |
514 TypeVariants::TyInfer(InferTy::FreshIntTy(_)) |
515 TypeVariants::TyInfer(InferTy::FreshFloatTy(_)) => true,
516 TypeVariants::TyRef(_, x) => x.ty.is_primitive_ty(),
521 pub fn is_suggestable(&self) -> bool {
523 TypeVariants::TyAnon(..) |
524 TypeVariants::TyFnDef(..) |
525 TypeVariants::TyFnPtr(..) |
526 TypeVariants::TyDynamic(..) |
527 TypeVariants::TyClosure(..) |
528 TypeVariants::TyInfer(..) |
529 TypeVariants::TyProjection(..) => false,
535 impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for ty::TyS<'gcx> {
536 fn hash_stable<W: StableHasherResult>(&self,
537 hcx: &mut StableHashingContext<'a>,
538 hasher: &mut StableHasher<W>) {
542 // The other fields just provide fast access to information that is
543 // also contained in `sty`, so no need to hash them.
548 sty.hash_stable(hcx, hasher);
552 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
554 impl<'tcx> serialize::UseSpecializedEncodable for Ty<'tcx> {}
555 impl<'tcx> serialize::UseSpecializedDecodable for Ty<'tcx> {}
557 /// A wrapper for slices with the additional invariant
558 /// that the slice is interned and no other slice with
559 /// the same contents can exist in the same context.
560 /// This means we can use pointer + length for both
561 /// equality comparisons and hashing.
562 #[derive(Debug, RustcEncodable)]
563 pub struct Slice<T>([T]);
565 impl<T> PartialEq for Slice<T> {
567 fn eq(&self, other: &Slice<T>) -> bool {
568 (&self.0 as *const [T]) == (&other.0 as *const [T])
571 impl<T> Eq for Slice<T> {}
573 impl<T> Hash for Slice<T> {
574 fn hash<H: Hasher>(&self, s: &mut H) {
575 (self.as_ptr(), self.len()).hash(s)
579 impl<T> Deref for Slice<T> {
581 fn deref(&self) -> &[T] {
586 impl<'a, T> IntoIterator for &'a Slice<T> {
588 type IntoIter = <&'a [T] as IntoIterator>::IntoIter;
589 fn into_iter(self) -> Self::IntoIter {
594 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Slice<Ty<'tcx>> {}
597 pub fn empty<'a>() -> &'a Slice<T> {
599 mem::transmute(slice::from_raw_parts(0x1 as *const T, 0))
604 /// Upvars do not get their own node-id. Instead, we use the pair of
605 /// the original var id (that is, the root variable that is referenced
606 /// by the upvar) and the id of the closure expression.
607 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
609 pub var_id: hir::HirId,
610 pub closure_expr_id: LocalDefId,
613 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, Copy)]
614 pub enum BorrowKind {
615 /// Data must be immutable and is aliasable.
618 /// Data must be immutable but not aliasable. This kind of borrow
619 /// cannot currently be expressed by the user and is used only in
620 /// implicit closure bindings. It is needed when the closure
621 /// is borrowing or mutating a mutable referent, e.g.:
623 /// let x: &mut isize = ...;
624 /// let y = || *x += 5;
626 /// If we were to try to translate this closure into a more explicit
627 /// form, we'd encounter an error with the code as written:
629 /// struct Env { x: & &mut isize }
630 /// let x: &mut isize = ...;
631 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
632 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
634 /// This is then illegal because you cannot mutate a `&mut` found
635 /// in an aliasable location. To solve, you'd have to translate with
636 /// an `&mut` borrow:
638 /// struct Env { x: & &mut isize }
639 /// let x: &mut isize = ...;
640 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
641 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
643 /// Now the assignment to `**env.x` is legal, but creating a
644 /// mutable pointer to `x` is not because `x` is not mutable. We
645 /// could fix this by declaring `x` as `let mut x`. This is ok in
646 /// user code, if awkward, but extra weird for closures, since the
647 /// borrow is hidden.
649 /// So we introduce a "unique imm" borrow -- the referent is
650 /// immutable, but not aliasable. This solves the problem. For
651 /// simplicity, we don't give users the way to express this
652 /// borrow, it's just used when translating closures.
655 /// Data is mutable and not aliasable.
659 /// Information describing the capture of an upvar. This is computed
660 /// during `typeck`, specifically by `regionck`.
661 #[derive(PartialEq, Clone, Debug, Copy, RustcEncodable, RustcDecodable)]
662 pub enum UpvarCapture<'tcx> {
663 /// Upvar is captured by value. This is always true when the
664 /// closure is labeled `move`, but can also be true in other cases
665 /// depending on inference.
668 /// Upvar is captured by reference.
669 ByRef(UpvarBorrow<'tcx>),
672 #[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable)]
673 pub struct UpvarBorrow<'tcx> {
674 /// The kind of borrow: by-ref upvars have access to shared
675 /// immutable borrows, which are not part of the normal language
677 pub kind: BorrowKind,
679 /// Region of the resulting reference.
680 pub region: ty::Region<'tcx>,
683 pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
685 #[derive(Copy, Clone)]
686 pub struct ClosureUpvar<'tcx> {
692 #[derive(Clone, Copy, PartialEq, Eq)]
693 pub enum IntVarValue {
695 UintType(ast::UintTy),
698 #[derive(Clone, Copy, PartialEq, Eq)]
699 pub struct FloatVarValue(pub ast::FloatTy);
701 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
702 pub struct TypeParameterDef {
706 pub has_default: bool,
707 pub object_lifetime_default: ObjectLifetimeDefault,
709 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
710 /// on generic parameter `T`, asserts data behind the parameter
711 /// `T` won't be accessed during the parent type's `Drop` impl.
712 pub pure_wrt_drop: bool,
714 pub synthetic: Option<hir::SyntheticTyParamKind>,
717 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
718 pub struct RegionParameterDef {
723 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
724 /// on generic parameter `'a`, asserts data of lifetime `'a`
725 /// won't be accessed during the parent type's `Drop` impl.
726 pub pure_wrt_drop: bool,
729 impl RegionParameterDef {
730 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
731 ty::EarlyBoundRegion {
738 pub fn to_bound_region(&self) -> ty::BoundRegion {
739 self.to_early_bound_region_data().to_bound_region()
743 impl ty::EarlyBoundRegion {
744 pub fn to_bound_region(&self) -> ty::BoundRegion {
745 ty::BoundRegion::BrNamed(self.def_id, self.name)
749 /// Information about the formal type/lifetime parameters associated
750 /// with an item or method. Analogous to hir::Generics.
752 /// Note that in the presence of a `Self` parameter, the ordering here
753 /// is different from the ordering in a Substs. Substs are ordered as
754 /// Self, *Regions, *Other Type Params, (...child generics)
755 /// while this struct is ordered as
756 /// regions = Regions
757 /// types = [Self, *Other Type Params]
758 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
759 pub struct Generics {
760 pub parent: Option<DefId>,
761 pub parent_regions: u32,
762 pub parent_types: u32,
763 pub regions: Vec<RegionParameterDef>,
764 pub types: Vec<TypeParameterDef>,
766 /// Reverse map to each `TypeParameterDef`'s `index` field
767 pub type_param_to_index: FxHashMap<DefId, u32>,
770 pub has_late_bound_regions: Option<Span>,
773 impl<'a, 'gcx, 'tcx> Generics {
774 pub fn parent_count(&self) -> usize {
775 self.parent_regions as usize + self.parent_types as usize
778 pub fn own_count(&self) -> usize {
779 self.regions.len() + self.types.len()
782 pub fn count(&self) -> usize {
783 self.parent_count() + self.own_count()
786 pub fn region_param(&'tcx self,
787 param: &EarlyBoundRegion,
788 tcx: TyCtxt<'a, 'gcx, 'tcx>)
789 -> &'tcx RegionParameterDef
791 if let Some(index) = param.index.checked_sub(self.parent_count() as u32) {
792 &self.regions[index as usize - self.has_self as usize]
794 tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
795 .region_param(param, tcx)
799 /// Returns the `TypeParameterDef` associated with this `ParamTy`.
800 pub fn type_param(&'tcx self,
802 tcx: TyCtxt<'a, 'gcx, 'tcx>)
803 -> &TypeParameterDef {
804 if let Some(idx) = param.idx.checked_sub(self.parent_count() as u32) {
805 // non-Self type parameters are always offset by exactly
806 // `self.regions.len()`. In the absence of a Self, this is obvious,
807 // but even in the presence of a `Self` we just have to "compensate"
810 // Without a `Self` (or in a nested generics that doesn't have
811 // a `Self` in itself, even through it parent does), for example
812 // for `fn foo<'a, T1, T2>()`, the situation is:
820 // And with a `Self`, for example for `trait Foo<'a, 'b, T1, T2>`, the
829 // And it can be seen that in both cases, to move from a substs
830 // offset to a generics offset you just have to offset by the
831 // number of regions.
832 let type_param_offset = self.regions.len();
834 let has_self = self.has_self && self.parent.is_none();
835 let is_separated_self = type_param_offset != 0 && idx == 0 && has_self;
837 if let Some(idx) = (idx as usize).checked_sub(type_param_offset) {
838 assert!(!is_separated_self, "found a Self after type_param_offset");
841 assert!(is_separated_self, "non-Self param before type_param_offset");
845 tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
846 .type_param(param, tcx)
851 /// Bounds on generics.
852 #[derive(Clone, Default)]
853 pub struct GenericPredicates<'tcx> {
854 pub parent: Option<DefId>,
855 pub predicates: Vec<Predicate<'tcx>>,
858 impl<'tcx> serialize::UseSpecializedEncodable for GenericPredicates<'tcx> {}
859 impl<'tcx> serialize::UseSpecializedDecodable for GenericPredicates<'tcx> {}
861 impl<'a, 'gcx, 'tcx> GenericPredicates<'tcx> {
862 pub fn instantiate(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>)
863 -> InstantiatedPredicates<'tcx> {
864 let mut instantiated = InstantiatedPredicates::empty();
865 self.instantiate_into(tcx, &mut instantiated, substs);
868 pub fn instantiate_own(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>)
869 -> InstantiatedPredicates<'tcx> {
870 InstantiatedPredicates {
871 predicates: self.predicates.subst(tcx, substs)
875 fn instantiate_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
876 instantiated: &mut InstantiatedPredicates<'tcx>,
877 substs: &Substs<'tcx>) {
878 if let Some(def_id) = self.parent {
879 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
881 instantiated.predicates.extend(self.predicates.iter().map(|p| p.subst(tcx, substs)))
884 pub fn instantiate_identity(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>)
885 -> InstantiatedPredicates<'tcx> {
886 let mut instantiated = InstantiatedPredicates::empty();
887 self.instantiate_identity_into(tcx, &mut instantiated);
891 fn instantiate_identity_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
892 instantiated: &mut InstantiatedPredicates<'tcx>) {
893 if let Some(def_id) = self.parent {
894 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
896 instantiated.predicates.extend(&self.predicates)
899 pub fn instantiate_supertrait(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
900 poly_trait_ref: &ty::PolyTraitRef<'tcx>)
901 -> InstantiatedPredicates<'tcx>
903 assert_eq!(self.parent, None);
904 InstantiatedPredicates {
905 predicates: self.predicates.iter().map(|pred| {
906 pred.subst_supertrait(tcx, poly_trait_ref)
912 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
913 pub enum Predicate<'tcx> {
914 /// Corresponds to `where Foo : Bar<A,B,C>`. `Foo` here would be
915 /// the `Self` type of the trait reference and `A`, `B`, and `C`
916 /// would be the type parameters.
917 Trait(PolyTraitPredicate<'tcx>),
920 RegionOutlives(PolyRegionOutlivesPredicate<'tcx>),
923 TypeOutlives(PolyTypeOutlivesPredicate<'tcx>),
925 /// where <T as TraitRef>::Name == X, approximately.
926 /// See `ProjectionPredicate` struct for details.
927 Projection(PolyProjectionPredicate<'tcx>),
930 WellFormed(Ty<'tcx>),
932 /// trait must be object-safe
935 /// No direct syntax. May be thought of as `where T : FnFoo<...>`
936 /// for some substitutions `...` and T being a closure type.
937 /// Satisfied (or refuted) once we know the closure's kind.
938 ClosureKind(DefId, ClosureSubsts<'tcx>, ClosureKind),
941 Subtype(PolySubtypePredicate<'tcx>),
943 /// Constant initializer must evaluate successfully.
944 ConstEvaluatable(DefId, &'tcx Substs<'tcx>),
947 impl<'tcx> AsRef<Predicate<'tcx>> for Predicate<'tcx> {
948 fn as_ref(&self) -> &Predicate<'tcx> {
953 impl<'a, 'gcx, 'tcx> Predicate<'tcx> {
954 /// Performs a substitution suitable for going from a
955 /// poly-trait-ref to supertraits that must hold if that
956 /// poly-trait-ref holds. This is slightly different from a normal
957 /// substitution in terms of what happens with bound regions. See
958 /// lengthy comment below for details.
959 pub fn subst_supertrait(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
960 trait_ref: &ty::PolyTraitRef<'tcx>)
961 -> ty::Predicate<'tcx>
963 // The interaction between HRTB and supertraits is not entirely
964 // obvious. Let me walk you (and myself) through an example.
966 // Let's start with an easy case. Consider two traits:
968 // trait Foo<'a> : Bar<'a,'a> { }
969 // trait Bar<'b,'c> { }
971 // Now, if we have a trait reference `for<'x> T : Foo<'x>`, then
972 // we can deduce that `for<'x> T : Bar<'x,'x>`. Basically, if we
973 // knew that `Foo<'x>` (for any 'x) then we also know that
974 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
975 // normal substitution.
977 // In terms of why this is sound, the idea is that whenever there
978 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
979 // holds. So if there is an impl of `T:Foo<'a>` that applies to
980 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
983 // Another example to be careful of is this:
985 // trait Foo1<'a> : for<'b> Bar1<'a,'b> { }
986 // trait Bar1<'b,'c> { }
988 // Here, if we have `for<'x> T : Foo1<'x>`, then what do we know?
989 // The answer is that we know `for<'x,'b> T : Bar1<'x,'b>`. The
990 // reason is similar to the previous example: any impl of
991 // `T:Foo1<'x>` must show that `for<'b> T : Bar1<'x, 'b>`. So
992 // basically we would want to collapse the bound lifetimes from
993 // the input (`trait_ref`) and the supertraits.
995 // To achieve this in practice is fairly straightforward. Let's
996 // consider the more complicated scenario:
998 // - We start out with `for<'x> T : Foo1<'x>`. In this case, `'x`
999 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T : Bar1<'x,'b>`,
1000 // where both `'x` and `'b` would have a DB index of 1.
1001 // The substitution from the input trait-ref is therefore going to be
1002 // `'a => 'x` (where `'x` has a DB index of 1).
1003 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1004 // early-bound parameter and `'b' is a late-bound parameter with a
1006 // - If we replace `'a` with `'x` from the input, it too will have
1007 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1008 // just as we wanted.
1010 // There is only one catch. If we just apply the substitution `'a
1011 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1012 // adjust the DB index because we substituting into a binder (it
1013 // tries to be so smart...) resulting in `for<'x> for<'b>
1014 // Bar1<'x,'b>` (we have no syntax for this, so use your
1015 // imagination). Basically the 'x will have DB index of 2 and 'b
1016 // will have DB index of 1. Not quite what we want. So we apply
1017 // the substitution to the *contents* of the trait reference,
1018 // rather than the trait reference itself (put another way, the
1019 // substitution code expects equal binding levels in the values
1020 // from the substitution and the value being substituted into, and
1021 // this trick achieves that).
1023 let substs = &trait_ref.0.substs;
1025 Predicate::Trait(ty::Binder(ref data)) =>
1026 Predicate::Trait(ty::Binder(data.subst(tcx, substs))),
1027 Predicate::Subtype(ty::Binder(ref data)) =>
1028 Predicate::Subtype(ty::Binder(data.subst(tcx, substs))),
1029 Predicate::RegionOutlives(ty::Binder(ref data)) =>
1030 Predicate::RegionOutlives(ty::Binder(data.subst(tcx, substs))),
1031 Predicate::TypeOutlives(ty::Binder(ref data)) =>
1032 Predicate::TypeOutlives(ty::Binder(data.subst(tcx, substs))),
1033 Predicate::Projection(ty::Binder(ref data)) =>
1034 Predicate::Projection(ty::Binder(data.subst(tcx, substs))),
1035 Predicate::WellFormed(data) =>
1036 Predicate::WellFormed(data.subst(tcx, substs)),
1037 Predicate::ObjectSafe(trait_def_id) =>
1038 Predicate::ObjectSafe(trait_def_id),
1039 Predicate::ClosureKind(closure_def_id, closure_substs, kind) =>
1040 Predicate::ClosureKind(closure_def_id, closure_substs.subst(tcx, substs), kind),
1041 Predicate::ConstEvaluatable(def_id, const_substs) =>
1042 Predicate::ConstEvaluatable(def_id, const_substs.subst(tcx, substs)),
1047 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1048 pub struct TraitPredicate<'tcx> {
1049 pub trait_ref: TraitRef<'tcx>
1051 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1053 impl<'tcx> TraitPredicate<'tcx> {
1054 pub fn def_id(&self) -> DefId {
1055 self.trait_ref.def_id
1058 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
1059 self.trait_ref.input_types()
1062 pub fn self_ty(&self) -> Ty<'tcx> {
1063 self.trait_ref.self_ty()
1067 impl<'tcx> PolyTraitPredicate<'tcx> {
1068 pub fn def_id(&self) -> DefId {
1069 // ok to skip binder since trait def-id does not care about regions
1074 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1075 pub struct OutlivesPredicate<A,B>(pub A, pub B); // `A : B`
1076 pub type PolyOutlivesPredicate<A,B> = ty::Binder<OutlivesPredicate<A,B>>;
1077 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>,
1079 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>,
1081 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>;
1082 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>;
1084 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1085 pub struct SubtypePredicate<'tcx> {
1086 pub a_is_expected: bool,
1090 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1092 /// This kind of predicate has no *direct* correspondent in the
1093 /// syntax, but it roughly corresponds to the syntactic forms:
1095 /// 1. `T : TraitRef<..., Item=Type>`
1096 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1098 /// In particular, form #1 is "desugared" to the combination of a
1099 /// normal trait predicate (`T : TraitRef<...>`) and one of these
1100 /// predicates. Form #2 is a broader form in that it also permits
1101 /// equality between arbitrary types. Processing an instance of
1102 /// Form #2 eventually yields one of these `ProjectionPredicate`
1103 /// instances to normalize the LHS.
1104 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1105 pub struct ProjectionPredicate<'tcx> {
1106 pub projection_ty: ProjectionTy<'tcx>,
1110 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1112 impl<'tcx> PolyProjectionPredicate<'tcx> {
1113 pub fn to_poly_trait_ref(&self, tcx: TyCtxt) -> PolyTraitRef<'tcx> {
1114 // Note: unlike with TraitRef::to_poly_trait_ref(),
1115 // self.0.trait_ref is permitted to have escaping regions.
1116 // This is because here `self` has a `Binder` and so does our
1117 // return value, so we are preserving the number of binding
1119 ty::Binder(self.0.projection_ty.trait_ref(tcx))
1122 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1123 Binder(self.skip_binder().ty) // preserves binding levels
1127 pub trait ToPolyTraitRef<'tcx> {
1128 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1131 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1132 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1133 assert!(!self.has_escaping_regions());
1134 ty::Binder(self.clone())
1138 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1139 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1140 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1144 pub trait ToPredicate<'tcx> {
1145 fn to_predicate(&self) -> Predicate<'tcx>;
1148 impl<'tcx> ToPredicate<'tcx> for TraitRef<'tcx> {
1149 fn to_predicate(&self) -> Predicate<'tcx> {
1150 // we're about to add a binder, so let's check that we don't
1151 // accidentally capture anything, or else that might be some
1152 // weird debruijn accounting.
1153 assert!(!self.has_escaping_regions());
1155 ty::Predicate::Trait(ty::Binder(ty::TraitPredicate {
1156 trait_ref: self.clone()
1161 impl<'tcx> ToPredicate<'tcx> for PolyTraitRef<'tcx> {
1162 fn to_predicate(&self) -> Predicate<'tcx> {
1163 ty::Predicate::Trait(self.to_poly_trait_predicate())
1167 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1168 fn to_predicate(&self) -> Predicate<'tcx> {
1169 Predicate::RegionOutlives(self.clone())
1173 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1174 fn to_predicate(&self) -> Predicate<'tcx> {
1175 Predicate::TypeOutlives(self.clone())
1179 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1180 fn to_predicate(&self) -> Predicate<'tcx> {
1181 Predicate::Projection(self.clone())
1185 impl<'tcx> Predicate<'tcx> {
1186 /// Iterates over the types in this predicate. Note that in all
1187 /// cases this is skipping over a binder, so late-bound regions
1188 /// with depth 0 are bound by the predicate.
1189 pub fn walk_tys(&self) -> IntoIter<Ty<'tcx>> {
1190 let vec: Vec<_> = match *self {
1191 ty::Predicate::Trait(ref data) => {
1192 data.skip_binder().input_types().collect()
1194 ty::Predicate::Subtype(ty::Binder(SubtypePredicate { a, b, a_is_expected: _ })) => {
1197 ty::Predicate::TypeOutlives(ty::Binder(ref data)) => {
1200 ty::Predicate::RegionOutlives(..) => {
1203 ty::Predicate::Projection(ref data) => {
1204 data.0.projection_ty.substs.types().chain(Some(data.0.ty)).collect()
1206 ty::Predicate::WellFormed(data) => {
1209 ty::Predicate::ObjectSafe(_trait_def_id) => {
1212 ty::Predicate::ClosureKind(_closure_def_id, closure_substs, _kind) => {
1213 closure_substs.substs.types().collect()
1215 ty::Predicate::ConstEvaluatable(_, substs) => {
1216 substs.types().collect()
1220 // The only reason to collect into a vector here is that I was
1221 // too lazy to make the full (somewhat complicated) iterator
1222 // type that would be needed here. But I wanted this fn to
1223 // return an iterator conceptually, rather than a `Vec`, so as
1224 // to be closer to `Ty::walk`.
1228 pub fn to_opt_poly_trait_ref(&self) -> Option<PolyTraitRef<'tcx>> {
1230 Predicate::Trait(ref t) => {
1231 Some(t.to_poly_trait_ref())
1233 Predicate::Projection(..) |
1234 Predicate::Subtype(..) |
1235 Predicate::RegionOutlives(..) |
1236 Predicate::WellFormed(..) |
1237 Predicate::ObjectSafe(..) |
1238 Predicate::ClosureKind(..) |
1239 Predicate::TypeOutlives(..) |
1240 Predicate::ConstEvaluatable(..) => {
1246 pub fn to_opt_type_outlives(&self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1248 Predicate::TypeOutlives(data) => {
1251 Predicate::Trait(..) |
1252 Predicate::Projection(..) |
1253 Predicate::Subtype(..) |
1254 Predicate::RegionOutlives(..) |
1255 Predicate::WellFormed(..) |
1256 Predicate::ObjectSafe(..) |
1257 Predicate::ClosureKind(..) |
1258 Predicate::ConstEvaluatable(..) => {
1265 /// Represents the bounds declared on a particular set of type
1266 /// parameters. Should eventually be generalized into a flag list of
1267 /// where clauses. You can obtain a `InstantiatedPredicates` list from a
1268 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1269 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1270 /// the `GenericPredicates` are expressed in terms of the bound type
1271 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1272 /// represented a set of bounds for some particular instantiation,
1273 /// meaning that the generic parameters have been substituted with
1278 /// struct Foo<T,U:Bar<T>> { ... }
1280 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1281 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1282 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1283 /// [usize:Bar<isize>]]`.
1285 pub struct InstantiatedPredicates<'tcx> {
1286 pub predicates: Vec<Predicate<'tcx>>,
1289 impl<'tcx> InstantiatedPredicates<'tcx> {
1290 pub fn empty() -> InstantiatedPredicates<'tcx> {
1291 InstantiatedPredicates { predicates: vec![] }
1294 pub fn is_empty(&self) -> bool {
1295 self.predicates.is_empty()
1299 /// "Universes" are used during type- and trait-checking in the
1300 /// presence of `for<..>` binders to control what sets of names are
1301 /// visible. Universes are arranged into a tree: the root universe
1302 /// contains names that are always visible. But when you enter into
1303 /// some subuniverse, then it may add names that are only visible
1304 /// within that subtree (but it can still name the names of its
1305 /// ancestor universes).
1307 /// To make this more concrete, consider this program:
1311 /// fn bar<T>(x: T) {
1312 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1316 /// The struct name `Foo` is in the root universe U0. But the type
1317 /// parameter `T`, introduced on `bar`, is in a subuniverse U1 --
1318 /// i.e., within `bar`, we can name both `T` and `Foo`, but outside of
1319 /// `bar`, we cannot name `T`. Then, within the type of `y`, the
1320 /// region `'a` is in a subuniverse U2 of U1, because we can name it
1321 /// inside the fn type but not outside.
1323 /// Universes are related to **skolemization** -- which is a way of
1324 /// doing type- and trait-checking around these "forall" binders (also
1325 /// called **universal quantification**). The idea is that when, in
1326 /// the body of `bar`, we refer to `T` as a type, we aren't referring
1327 /// to any type in particular, but rather a kind of "fresh" type that
1328 /// is distinct from all other types we have actually declared. This
1329 /// is called a **skolemized** type, and we use universes to talk
1330 /// about this. In other words, a type name in universe 0 always
1331 /// corresponds to some "ground" type that the user declared, but a
1332 /// type name in a non-zero universe is a skolemized type -- an
1333 /// idealized representative of "types in general" that we use for
1334 /// checking generic functions.
1335 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1336 pub struct UniverseIndex(u32);
1338 impl UniverseIndex {
1339 /// The root universe, where things that the user defined are
1341 pub const ROOT: UniverseIndex = UniverseIndex(0);
1343 /// A "subuniverse" corresponds to being inside a `forall` quantifier.
1344 /// So, for example, suppose we have this type in universe `U`:
1347 /// for<'a> fn(&'a u32)
1350 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1351 /// subuniverse of `U` -- in this new universe, we can name the
1352 /// region `'a`, but that region was not nameable from `U` because
1353 /// it was not in scope there.
1354 pub fn subuniverse(self) -> UniverseIndex {
1355 UniverseIndex(self.0.checked_add(1).unwrap())
1358 pub fn from(v: u32) -> UniverseIndex {
1362 pub fn as_u32(&self) -> u32 {
1366 pub fn as_usize(&self) -> usize {
1370 /// Gets the "depth" of this universe in the universe tree. This
1371 /// is not really useful except for e.g. the `HashStable`
1373 pub fn depth(&self) -> u32 {
1378 /// When type checking, we use the `ParamEnv` to track
1379 /// details about the set of where-clauses that are in scope at this
1380 /// particular point.
1381 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1382 pub struct ParamEnv<'tcx> {
1383 /// Obligations that the caller must satisfy. This is basically
1384 /// the set of bounds on the in-scope type parameters, translated
1385 /// into Obligations, and elaborated and normalized.
1386 pub caller_bounds: &'tcx Slice<ty::Predicate<'tcx>>,
1388 /// Typically, this is `Reveal::UserFacing`, but during trans we
1389 /// want `Reveal::All` -- note that this is always paired with an
1390 /// empty environment. To get that, use `ParamEnv::reveal()`.
1391 pub reveal: traits::Reveal,
1393 /// What is the innermost universe we have created? Starts out as
1394 /// `UniverseIndex::root()` but grows from there as we enter
1395 /// universal quantifiers.
1397 /// NB: At present, we exclude the universal quantifiers on the
1398 /// item we are type-checking, and just consider those names as
1399 /// part of the root universe. So this would only get incremented
1400 /// when we enter into a higher-ranked (`for<..>`) type or trait
1402 pub universe: UniverseIndex,
1405 impl<'tcx> ParamEnv<'tcx> {
1406 /// Construct a trait environment suitable for contexts where
1407 /// there are no where clauses in scope. Hidden types (like `impl
1408 /// Trait`) are left hidden, so this is suitable for ordinary
1410 pub fn empty() -> Self {
1411 Self::new(ty::Slice::empty(), Reveal::UserFacing, ty::UniverseIndex::ROOT)
1414 /// Construct a trait environment with no where clauses in scope
1415 /// where the values of all `impl Trait` and other hidden types
1416 /// are revealed. This is suitable for monomorphized, post-typeck
1417 /// environments like trans or doing optimizations.
1419 /// NB. If you want to have predicates in scope, use `ParamEnv::new`,
1420 /// or invoke `param_env.with_reveal_all()`.
1421 pub fn reveal_all() -> Self {
1422 Self::new(ty::Slice::empty(), Reveal::All, ty::UniverseIndex::ROOT)
1425 /// Construct a trait environment with the given set of predicates.
1426 pub fn new(caller_bounds: &'tcx ty::Slice<ty::Predicate<'tcx>>,
1428 universe: ty::UniverseIndex)
1430 ty::ParamEnv { caller_bounds, reveal, universe }
1433 /// Returns a new parameter environment with the same clauses, but
1434 /// which "reveals" the true results of projections in all cases
1435 /// (even for associated types that are specializable). This is
1436 /// the desired behavior during trans and certain other special
1437 /// contexts; normally though we want to use `Reveal::UserFacing`,
1438 /// which is the default.
1439 pub fn with_reveal_all(self) -> Self {
1440 ty::ParamEnv { reveal: Reveal::All, ..self }
1443 /// Returns this same environment but with no caller bounds.
1444 pub fn without_caller_bounds(self) -> Self {
1445 ty::ParamEnv { caller_bounds: ty::Slice::empty(), ..self }
1448 /// Creates a suitable environment in which to perform trait
1449 /// queries on the given value. When type-checking, this is simply
1450 /// the pair of the environment plus value. But when reveal is set to
1451 /// All, then if `value` does not reference any type parameters, we will
1452 /// pair it with the empty environment. This improves caching and is generally
1455 /// NB: We preserve the environment when type-checking because it
1456 /// is possible for the user to have wacky where-clauses like
1457 /// `where Box<u32>: Copy`, which are clearly never
1458 /// satisfiable. We generally want to behave as if they were true,
1459 /// although the surrounding function is never reachable.
1460 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1462 Reveal::UserFacing => {
1470 if value.needs_infer() || value.has_param_types() || value.has_self_ty() {
1477 param_env: self.without_caller_bounds(),
1486 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1487 pub struct ParamEnvAnd<'tcx, T> {
1488 pub param_env: ParamEnv<'tcx>,
1492 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1493 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1494 (self.param_env, self.value)
1498 impl<'a, 'gcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'gcx, T>
1499 where T: HashStable<StableHashingContext<'a>>
1501 fn hash_stable<W: StableHasherResult>(&self,
1502 hcx: &mut StableHashingContext<'a>,
1503 hasher: &mut StableHasher<W>) {
1509 param_env.hash_stable(hcx, hasher);
1510 value.hash_stable(hcx, hasher);
1514 #[derive(Copy, Clone, Debug)]
1515 pub struct Destructor {
1516 /// The def-id of the destructor method
1521 pub struct AdtFlags: u32 {
1522 const NO_ADT_FLAGS = 0;
1523 const IS_ENUM = 1 << 0;
1524 const IS_PHANTOM_DATA = 1 << 1;
1525 const IS_FUNDAMENTAL = 1 << 2;
1526 const IS_UNION = 1 << 3;
1527 const IS_BOX = 1 << 4;
1528 /// Indicates whether this abstract data type will be expanded on in future (new
1529 /// fields/variants) and as such, whether downstream crates must match exhaustively on the
1530 /// fields/variants of this data type.
1532 /// See RFC 2008 (<https://github.com/rust-lang/rfcs/pull/2008>).
1533 const IS_NON_EXHAUSTIVE = 1 << 5;
1538 pub struct VariantDef {
1539 /// The variant's DefId. If this is a tuple-like struct,
1540 /// this is the DefId of the struct's ctor.
1542 pub name: Name, // struct's name if this is a struct
1543 pub discr: VariantDiscr,
1544 pub fields: Vec<FieldDef>,
1545 pub ctor_kind: CtorKind,
1548 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1549 pub enum VariantDiscr {
1550 /// Explicit value for this variant, i.e. `X = 123`.
1551 /// The `DefId` corresponds to the embedded constant.
1554 /// The previous variant's discriminant plus one.
1555 /// For efficiency reasons, the distance from the
1556 /// last `Explicit` discriminant is being stored,
1557 /// or `0` for the first variant, if it has none.
1562 pub struct FieldDef {
1565 pub vis: Visibility,
1568 /// The definition of an abstract data type - a struct or enum.
1570 /// These are all interned (by intern_adt_def) into the adt_defs
1574 pub variants: Vec<VariantDef>,
1576 pub repr: ReprOptions,
1579 impl PartialEq for AdtDef {
1580 // AdtDef are always interned and this is part of TyS equality
1582 fn eq(&self, other: &Self) -> bool { self as *const _ == other as *const _ }
1585 impl Eq for AdtDef {}
1587 impl Hash for AdtDef {
1589 fn hash<H: Hasher>(&self, s: &mut H) {
1590 (self as *const AdtDef).hash(s)
1594 impl<'tcx> serialize::UseSpecializedEncodable for &'tcx AdtDef {
1595 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1600 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx AdtDef {}
1603 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
1604 fn hash_stable<W: StableHasherResult>(&self,
1605 hcx: &mut StableHashingContext<'a>,
1606 hasher: &mut StableHasher<W>) {
1608 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> =
1609 RefCell::new(FxHashMap());
1612 let hash: Fingerprint = CACHE.with(|cache| {
1613 let addr = self as *const AdtDef as usize;
1614 *cache.borrow_mut().entry(addr).or_insert_with(|| {
1622 let mut hasher = StableHasher::new();
1623 did.hash_stable(hcx, &mut hasher);
1624 variants.hash_stable(hcx, &mut hasher);
1625 flags.hash_stable(hcx, &mut hasher);
1626 repr.hash_stable(hcx, &mut hasher);
1632 hash.hash_stable(hcx, hasher);
1636 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
1637 pub enum AdtKind { Struct, Union, Enum }
1640 #[derive(RustcEncodable, RustcDecodable, Default)]
1641 pub struct ReprFlags: u8 {
1642 const IS_C = 1 << 0;
1643 const IS_PACKED = 1 << 1;
1644 const IS_SIMD = 1 << 2;
1645 const IS_TRANSPARENT = 1 << 3;
1646 // Internal only for now. If true, don't reorder fields.
1647 const IS_LINEAR = 1 << 4;
1649 // Any of these flags being set prevent field reordering optimisation.
1650 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
1651 ReprFlags::IS_PACKED.bits |
1652 ReprFlags::IS_SIMD.bits |
1653 ReprFlags::IS_LINEAR.bits;
1657 impl_stable_hash_for!(struct ReprFlags {
1663 /// Represents the repr options provided by the user,
1664 #[derive(Copy, Clone, Eq, PartialEq, RustcEncodable, RustcDecodable, Default)]
1665 pub struct ReprOptions {
1666 pub int: Option<attr::IntType>,
1668 pub flags: ReprFlags,
1671 impl_stable_hash_for!(struct ReprOptions {
1678 pub fn new(tcx: TyCtxt, did: DefId) -> ReprOptions {
1679 let mut flags = ReprFlags::empty();
1680 let mut size = None;
1681 let mut max_align = 0;
1682 for attr in tcx.get_attrs(did).iter() {
1683 for r in attr::find_repr_attrs(tcx.sess.diagnostic(), attr) {
1684 flags.insert(match r {
1685 attr::ReprC => ReprFlags::IS_C,
1686 attr::ReprPacked => ReprFlags::IS_PACKED,
1687 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1688 attr::ReprSimd => ReprFlags::IS_SIMD,
1689 attr::ReprInt(i) => {
1693 attr::ReprAlign(align) => {
1694 max_align = cmp::max(align, max_align);
1701 // This is here instead of layout because the choice must make it into metadata.
1702 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.item_path_str(did))) {
1703 flags.insert(ReprFlags::IS_LINEAR);
1705 ReprOptions { int: size, align: max_align, flags: flags }
1709 pub fn simd(&self) -> bool { self.flags.contains(ReprFlags::IS_SIMD) }
1711 pub fn c(&self) -> bool { self.flags.contains(ReprFlags::IS_C) }
1713 pub fn packed(&self) -> bool { self.flags.contains(ReprFlags::IS_PACKED) }
1715 pub fn transparent(&self) -> bool { self.flags.contains(ReprFlags::IS_TRANSPARENT) }
1717 pub fn linear(&self) -> bool { self.flags.contains(ReprFlags::IS_LINEAR) }
1719 pub fn discr_type(&self) -> attr::IntType {
1720 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1723 /// Returns true if this `#[repr()]` should inhabit "smart enum
1724 /// layout" optimizations, such as representing `Foo<&T>` as a
1726 pub fn inhibit_enum_layout_opt(&self) -> bool {
1727 self.c() || self.int.is_some()
1731 impl<'a, 'gcx, 'tcx> AdtDef {
1735 variants: Vec<VariantDef>,
1736 repr: ReprOptions) -> Self {
1737 let mut flags = AdtFlags::NO_ADT_FLAGS;
1738 let attrs = tcx.get_attrs(did);
1739 if attr::contains_name(&attrs, "fundamental") {
1740 flags = flags | AdtFlags::IS_FUNDAMENTAL;
1742 if Some(did) == tcx.lang_items().phantom_data() {
1743 flags = flags | AdtFlags::IS_PHANTOM_DATA;
1745 if Some(did) == tcx.lang_items().owned_box() {
1746 flags = flags | AdtFlags::IS_BOX;
1748 if tcx.has_attr(did, "non_exhaustive") {
1749 flags = flags | AdtFlags::IS_NON_EXHAUSTIVE;
1752 AdtKind::Enum => flags = flags | AdtFlags::IS_ENUM,
1753 AdtKind::Union => flags = flags | AdtFlags::IS_UNION,
1754 AdtKind::Struct => {}
1765 pub fn is_struct(&self) -> bool {
1766 !self.is_union() && !self.is_enum()
1770 pub fn is_union(&self) -> bool {
1771 self.flags.intersects(AdtFlags::IS_UNION)
1775 pub fn is_enum(&self) -> bool {
1776 self.flags.intersects(AdtFlags::IS_ENUM)
1780 pub fn is_non_exhaustive(&self) -> bool {
1781 self.flags.intersects(AdtFlags::IS_NON_EXHAUSTIVE)
1784 /// Returns the kind of the ADT - Struct or Enum.
1786 pub fn adt_kind(&self) -> AdtKind {
1789 } else if self.is_union() {
1796 pub fn descr(&self) -> &'static str {
1797 match self.adt_kind() {
1798 AdtKind::Struct => "struct",
1799 AdtKind::Union => "union",
1800 AdtKind::Enum => "enum",
1804 pub fn variant_descr(&self) -> &'static str {
1805 match self.adt_kind() {
1806 AdtKind::Struct => "struct",
1807 AdtKind::Union => "union",
1808 AdtKind::Enum => "variant",
1812 /// Returns whether this type is #[fundamental] for the purposes
1813 /// of coherence checking.
1815 pub fn is_fundamental(&self) -> bool {
1816 self.flags.intersects(AdtFlags::IS_FUNDAMENTAL)
1819 /// Returns true if this is PhantomData<T>.
1821 pub fn is_phantom_data(&self) -> bool {
1822 self.flags.intersects(AdtFlags::IS_PHANTOM_DATA)
1825 /// Returns true if this is Box<T>.
1827 pub fn is_box(&self) -> bool {
1828 self.flags.intersects(AdtFlags::IS_BOX)
1831 /// Returns whether this type has a destructor.
1832 pub fn has_dtor(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool {
1833 self.destructor(tcx).is_some()
1836 /// Asserts this is a struct or union and returns its unique variant.
1837 pub fn non_enum_variant(&self) -> &VariantDef {
1838 assert!(self.is_struct() || self.is_union());
1843 pub fn predicates(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> GenericPredicates<'gcx> {
1844 tcx.predicates_of(self.did)
1847 /// Returns an iterator over all fields contained
1850 pub fn all_fields<'s>(&'s self) -> impl Iterator<Item = &'s FieldDef> {
1851 self.variants.iter().flat_map(|v| v.fields.iter())
1854 pub fn is_payloadfree(&self) -> bool {
1855 !self.variants.is_empty() &&
1856 self.variants.iter().all(|v| v.fields.is_empty())
1859 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
1862 .find(|v| v.did == vid)
1863 .expect("variant_with_id: unknown variant")
1866 pub fn variant_index_with_id(&self, vid: DefId) -> usize {
1869 .position(|v| v.did == vid)
1870 .expect("variant_index_with_id: unknown variant")
1873 pub fn variant_of_def(&self, def: Def) -> &VariantDef {
1875 Def::Variant(vid) | Def::VariantCtor(vid, ..) => self.variant_with_id(vid),
1876 Def::Struct(..) | Def::StructCtor(..) | Def::Union(..) |
1877 Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => self.non_enum_variant(),
1878 _ => bug!("unexpected def {:?} in variant_of_def", def)
1883 pub fn eval_explicit_discr(
1885 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1887 ) -> Option<Discr<'tcx>> {
1888 let param_env = ParamEnv::empty();
1889 let repr_type = self.repr.discr_type();
1890 let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did);
1891 let instance = ty::Instance::new(expr_did, substs);
1892 let cid = GlobalId {
1896 match tcx.const_eval(param_env.and(cid)) {
1898 val: ConstVal::Value(Value::ByVal(PrimVal::Bytes(b))),
1901 trace!("discriminants: {} ({:?})", b, repr_type);
1908 val: ConstVal::Value(other),
1911 info!("invalid enum discriminant: {:#?}", other);
1912 ::middle::const_val::struct_error(
1914 tcx.def_span(expr_did),
1915 "constant evaluation of enum discriminant resulted in non-integer",
1920 err.report(tcx, tcx.def_span(expr_did), "enum discriminant");
1921 if !expr_did.is_local() {
1922 span_bug!(tcx.def_span(expr_did),
1923 "variant discriminant evaluation succeeded \
1924 in its crate but failed locally");
1928 _ => span_bug!(tcx.def_span(expr_did), "const eval "),
1933 pub fn discriminants(
1935 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1936 ) -> impl Iterator<Item=Discr<'tcx>> + Captures<'gcx> + 'a {
1937 let repr_type = self.repr.discr_type();
1938 let initial = repr_type.initial_discriminant(tcx.global_tcx());
1939 let mut prev_discr = None::<Discr<'tcx>>;
1940 self.variants.iter().map(move |v| {
1941 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
1942 if let VariantDiscr::Explicit(expr_did) = v.discr {
1943 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
1947 prev_discr = Some(discr);
1953 /// Compute the discriminant value used by a specific variant.
1954 /// Unlike `discriminants`, this is (amortized) constant-time,
1955 /// only doing at most one query for evaluating an explicit
1956 /// discriminant (the last one before the requested variant),
1957 /// assuming there are no constant-evaluation errors there.
1958 pub fn discriminant_for_variant(&self,
1959 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1960 variant_index: usize)
1962 let repr_type = self.repr.discr_type();
1963 let mut explicit_value = repr_type.initial_discriminant(tcx.global_tcx());
1964 let mut explicit_index = variant_index;
1966 match self.variants[explicit_index].discr {
1967 ty::VariantDiscr::Relative(0) => break,
1968 ty::VariantDiscr::Relative(distance) => {
1969 explicit_index -= distance;
1971 ty::VariantDiscr::Explicit(expr_did) => {
1972 match self.eval_explicit_discr(tcx, expr_did) {
1974 explicit_value = discr;
1978 if explicit_index == 0 {
1981 explicit_index -= 1;
1987 explicit_value.checked_add(tcx, (variant_index - explicit_index) as u128).0
1990 pub fn destructor(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Destructor> {
1991 tcx.adt_destructor(self.did)
1994 /// Returns a list of types such that `Self: Sized` if and only
1995 /// if that type is Sized, or `TyErr` if this type is recursive.
1997 /// Oddly enough, checking that the sized-constraint is Sized is
1998 /// actually more expressive than checking all members:
1999 /// the Sized trait is inductive, so an associated type that references
2000 /// Self would prevent its containing ADT from being Sized.
2002 /// Due to normalization being eager, this applies even if
2003 /// the associated type is behind a pointer, e.g. issue #31299.
2004 pub fn sized_constraint(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> &'tcx [Ty<'tcx>] {
2005 match queries::adt_sized_constraint::try_get(tcx, DUMMY_SP, self.did) {
2008 debug!("adt_sized_constraint: {:?} is recursive", self);
2009 // This should be reported as an error by `check_representable`.
2011 // Consider the type as Sized in the meanwhile to avoid
2012 // further errors. Delay our `bug` diagnostic here to get
2013 // emitted later as well in case we accidentally otherwise don't
2016 tcx.intern_type_list(&[tcx.types.err])
2021 fn sized_constraint_for_ty(&self,
2022 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2025 let result = match ty.sty {
2026 TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) |
2027 TyRawPtr(..) | TyRef(..) | TyFnDef(..) | TyFnPtr(_) |
2028 TyArray(..) | TyClosure(..) | TyGenerator(..) | TyNever => {
2037 TyGeneratorWitness(..) => {
2038 // these are never sized - return the target type
2042 TyTuple(ref tys) => {
2045 Some(ty) => self.sized_constraint_for_ty(tcx, ty)
2049 TyAdt(adt, substs) => {
2051 let adt_tys = adt.sized_constraint(tcx);
2052 debug!("sized_constraint_for_ty({:?}) intermediate = {:?}",
2055 .map(|ty| ty.subst(tcx, substs))
2056 .flat_map(|ty| self.sized_constraint_for_ty(tcx, ty))
2060 TyProjection(..) | TyAnon(..) => {
2061 // must calculate explicitly.
2062 // FIXME: consider special-casing always-Sized projections
2067 // perf hack: if there is a `T: Sized` bound, then
2068 // we know that `T` is Sized and do not need to check
2071 let sized_trait = match tcx.lang_items().sized_trait() {
2073 _ => return vec![ty]
2075 let sized_predicate = Binder(TraitRef {
2076 def_id: sized_trait,
2077 substs: tcx.mk_substs_trait(ty, &[])
2079 let predicates = tcx.predicates_of(self.did).predicates;
2080 if predicates.into_iter().any(|p| p == sized_predicate) {
2088 bug!("unexpected type `{:?}` in sized_constraint_for_ty",
2092 debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result);
2097 impl<'a, 'gcx, 'tcx> VariantDef {
2099 pub fn find_field_named(&self, name: ast::Name) -> Option<&FieldDef> {
2100 self.index_of_field_named(name).map(|index| &self.fields[index])
2103 pub fn index_of_field_named(&self, name: ast::Name) -> Option<usize> {
2104 if let Some(index) = self.fields.iter().position(|f| f.name == name) {
2107 let mut ident = name.to_ident();
2108 while ident.ctxt != SyntaxContext::empty() {
2109 ident.ctxt.remove_mark();
2110 if let Some(field) = self.fields.iter().position(|f| f.name.to_ident() == ident) {
2118 pub fn field_named(&self, name: ast::Name) -> &FieldDef {
2119 self.find_field_named(name).unwrap()
2123 impl<'a, 'gcx, 'tcx> FieldDef {
2124 pub fn ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, subst: &Substs<'tcx>) -> Ty<'tcx> {
2125 tcx.type_of(self.did).subst(tcx, subst)
2129 /// Represents the various closure traits in the Rust language. This
2130 /// will determine the type of the environment (`self`, in the
2131 /// desuaring) argument that the closure expects.
2133 /// You can get the environment type of a closure using
2134 /// `tcx.closure_env_ty()`.
2135 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
2136 pub enum ClosureKind {
2137 // Warning: Ordering is significant here! The ordering is chosen
2138 // because the trait Fn is a subtrait of FnMut and so in turn, and
2139 // hence we order it so that Fn < FnMut < FnOnce.
2145 impl<'a, 'tcx> ClosureKind {
2146 // This is the initial value used when doing upvar inference.
2147 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2149 pub fn trait_did(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> DefId {
2151 ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem),
2152 ClosureKind::FnMut => {
2153 tcx.require_lang_item(FnMutTraitLangItem)
2155 ClosureKind::FnOnce => {
2156 tcx.require_lang_item(FnOnceTraitLangItem)
2161 /// True if this a type that impls this closure kind
2162 /// must also implement `other`.
2163 pub fn extends(self, other: ty::ClosureKind) -> bool {
2164 match (self, other) {
2165 (ClosureKind::Fn, ClosureKind::Fn) => true,
2166 (ClosureKind::Fn, ClosureKind::FnMut) => true,
2167 (ClosureKind::Fn, ClosureKind::FnOnce) => true,
2168 (ClosureKind::FnMut, ClosureKind::FnMut) => true,
2169 (ClosureKind::FnMut, ClosureKind::FnOnce) => true,
2170 (ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
2175 /// Returns the representative scalar type for this closure kind.
2176 /// See `TyS::to_opt_closure_kind` for more details.
2177 pub fn to_ty(self, tcx: TyCtxt<'_, '_, 'tcx>) -> Ty<'tcx> {
2179 ty::ClosureKind::Fn => tcx.types.i8,
2180 ty::ClosureKind::FnMut => tcx.types.i16,
2181 ty::ClosureKind::FnOnce => tcx.types.i32,
2186 impl<'tcx> TyS<'tcx> {
2187 /// Iterator that walks `self` and any types reachable from
2188 /// `self`, in depth-first order. Note that just walks the types
2189 /// that appear in `self`, it does not descend into the fields of
2190 /// structs or variants. For example:
2193 /// isize => { isize }
2194 /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
2195 /// [isize] => { [isize], isize }
2197 pub fn walk(&'tcx self) -> TypeWalker<'tcx> {
2198 TypeWalker::new(self)
2201 /// Iterator that walks the immediate children of `self`. Hence
2202 /// `Foo<Bar<i32>, u32>` yields the sequence `[Bar<i32>, u32]`
2203 /// (but not `i32`, like `walk`).
2204 pub fn walk_shallow(&'tcx self) -> AccIntoIter<walk::TypeWalkerArray<'tcx>> {
2205 walk::walk_shallow(self)
2208 /// Walks `ty` and any types appearing within `ty`, invoking the
2209 /// callback `f` on each type. If the callback returns false, then the
2210 /// children of the current type are ignored.
2212 /// Note: prefer `ty.walk()` where possible.
2213 pub fn maybe_walk<F>(&'tcx self, mut f: F)
2214 where F : FnMut(Ty<'tcx>) -> bool
2216 let mut walker = self.walk();
2217 while let Some(ty) = walker.next() {
2219 walker.skip_current_subtree();
2226 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2228 hir::MutMutable => MutBorrow,
2229 hir::MutImmutable => ImmBorrow,
2233 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2234 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2235 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2237 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2239 MutBorrow => hir::MutMutable,
2240 ImmBorrow => hir::MutImmutable,
2242 // We have no type corresponding to a unique imm borrow, so
2243 // use `&mut`. It gives all the capabilities of an `&uniq`
2244 // and hence is a safe "over approximation".
2245 UniqueImmBorrow => hir::MutMutable,
2249 pub fn to_user_str(&self) -> &'static str {
2251 MutBorrow => "mutable",
2252 ImmBorrow => "immutable",
2253 UniqueImmBorrow => "uniquely immutable",
2258 #[derive(Debug, Clone)]
2259 pub enum Attributes<'gcx> {
2260 Owned(Lrc<[ast::Attribute]>),
2261 Borrowed(&'gcx [ast::Attribute])
2264 impl<'gcx> ::std::ops::Deref for Attributes<'gcx> {
2265 type Target = [ast::Attribute];
2267 fn deref(&self) -> &[ast::Attribute] {
2269 &Attributes::Owned(ref data) => &data,
2270 &Attributes::Borrowed(data) => data
2275 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
2276 pub fn body_tables(self, body: hir::BodyId) -> &'gcx TypeckTables<'gcx> {
2277 self.typeck_tables_of(self.hir.body_owner_def_id(body))
2280 /// Returns an iterator of the def-ids for all body-owners in this
2281 /// crate. If you would prefer to iterate over the bodies
2282 /// themselves, you can do `self.hir.krate().body_ids.iter()`.
2285 ) -> impl Iterator<Item = DefId> + Captures<'tcx> + Captures<'gcx> + 'a {
2289 .map(move |&body_id| self.hir.body_owner_def_id(body_id))
2292 pub fn expr_span(self, id: NodeId) -> Span {
2293 match self.hir.find(id) {
2294 Some(hir_map::NodeExpr(e)) => {
2298 bug!("Node id {} is not an expr: {:?}", id, f);
2301 bug!("Node id {} is not present in the node map", id);
2306 pub fn provided_trait_methods(self, id: DefId) -> Vec<AssociatedItem> {
2307 self.associated_items(id)
2308 .filter(|item| item.kind == AssociatedKind::Method && item.defaultness.has_value())
2312 pub fn trait_relevant_for_never(self, did: DefId) -> bool {
2313 self.associated_items(did).any(|item| {
2314 item.relevant_for_never()
2318 pub fn opt_associated_item(self, def_id: DefId) -> Option<AssociatedItem> {
2319 let is_associated_item = if let Some(node_id) = self.hir.as_local_node_id(def_id) {
2320 match self.hir.get(node_id) {
2321 hir_map::NodeTraitItem(_) | hir_map::NodeImplItem(_) => true,
2325 match self.describe_def(def_id).expect("no def for def-id") {
2326 Def::AssociatedConst(_) | Def::Method(_) | Def::AssociatedTy(_) => true,
2331 if is_associated_item {
2332 Some(self.associated_item(def_id))
2338 fn associated_item_from_trait_item_ref(self,
2339 parent_def_id: DefId,
2340 parent_vis: &hir::Visibility,
2341 trait_item_ref: &hir::TraitItemRef)
2343 let def_id = self.hir.local_def_id(trait_item_ref.id.node_id);
2344 let (kind, has_self) = match trait_item_ref.kind {
2345 hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false),
2346 hir::AssociatedItemKind::Method { has_self } => {
2347 (ty::AssociatedKind::Method, has_self)
2349 hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false),
2353 name: trait_item_ref.name,
2355 // Visibility of trait items is inherited from their traits.
2356 vis: Visibility::from_hir(parent_vis, trait_item_ref.id.node_id, self),
2357 defaultness: trait_item_ref.defaultness,
2359 container: TraitContainer(parent_def_id),
2360 method_has_self_argument: has_self
2364 fn associated_item_from_impl_item_ref(self,
2365 parent_def_id: DefId,
2366 impl_item_ref: &hir::ImplItemRef)
2368 let def_id = self.hir.local_def_id(impl_item_ref.id.node_id);
2369 let (kind, has_self) = match impl_item_ref.kind {
2370 hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false),
2371 hir::AssociatedItemKind::Method { has_self } => {
2372 (ty::AssociatedKind::Method, has_self)
2374 hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false),
2377 ty::AssociatedItem {
2378 name: impl_item_ref.name,
2380 // Visibility of trait impl items doesn't matter.
2381 vis: ty::Visibility::from_hir(&impl_item_ref.vis, impl_item_ref.id.node_id, self),
2382 defaultness: impl_item_ref.defaultness,
2384 container: ImplContainer(parent_def_id),
2385 method_has_self_argument: has_self
2389 pub fn associated_items(
2392 ) -> impl Iterator<Item = ty::AssociatedItem> + 'a {
2393 let def_ids = self.associated_item_def_ids(def_id);
2394 Box::new((0..def_ids.len()).map(move |i| self.associated_item(def_ids[i])))
2395 as Box<dyn Iterator<Item = ty::AssociatedItem> + 'a>
2398 /// Returns true if the impls are the same polarity and are implementing
2399 /// a trait which contains no items
2400 pub fn impls_are_allowed_to_overlap(self, def_id1: DefId, def_id2: DefId) -> bool {
2401 if !self.features().overlapping_marker_traits {
2404 let trait1_is_empty = self.impl_trait_ref(def_id1)
2405 .map_or(false, |trait_ref| {
2406 self.associated_item_def_ids(trait_ref.def_id).is_empty()
2408 let trait2_is_empty = self.impl_trait_ref(def_id2)
2409 .map_or(false, |trait_ref| {
2410 self.associated_item_def_ids(trait_ref.def_id).is_empty()
2412 self.impl_polarity(def_id1) == self.impl_polarity(def_id2)
2417 // Returns `ty::VariantDef` if `def` refers to a struct,
2418 // or variant or their constructors, panics otherwise.
2419 pub fn expect_variant_def(self, def: Def) -> &'tcx VariantDef {
2421 Def::Variant(did) | Def::VariantCtor(did, ..) => {
2422 let enum_did = self.parent_def_id(did).unwrap();
2423 self.adt_def(enum_did).variant_with_id(did)
2425 Def::Struct(did) | Def::Union(did) => {
2426 self.adt_def(did).non_enum_variant()
2428 Def::StructCtor(ctor_did, ..) => {
2429 let did = self.parent_def_id(ctor_did).expect("struct ctor has no parent");
2430 self.adt_def(did).non_enum_variant()
2432 _ => bug!("expect_variant_def used with unexpected def {:?}", def)
2436 /// Given a `VariantDef`, returns the def-id of the `AdtDef` of which it is a part.
2437 pub fn adt_def_id_of_variant(self, variant_def: &'tcx VariantDef) -> DefId {
2438 let def_key = self.def_key(variant_def.did);
2439 match def_key.disambiguated_data.data {
2440 // for enum variants and tuple structs, the def-id of the ADT itself
2441 // is the *parent* of the variant
2442 DefPathData::EnumVariant(..) | DefPathData::StructCtor =>
2443 DefId { krate: variant_def.did.krate, index: def_key.parent.unwrap() },
2445 // otherwise, for structs and unions, they share a def-id
2446 _ => variant_def.did,
2450 pub fn item_name(self, id: DefId) -> InternedString {
2451 if id.index == CRATE_DEF_INDEX {
2452 self.original_crate_name(id.krate).as_str()
2454 let def_key = self.def_key(id);
2455 // The name of a StructCtor is that of its struct parent.
2456 if let hir_map::DefPathData::StructCtor = def_key.disambiguated_data.data {
2457 self.item_name(DefId {
2459 index: def_key.parent.unwrap()
2462 def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
2463 bug!("item_name: no name for {:?}", self.def_path(id));
2469 /// Return the possibly-auto-generated MIR of a (DefId, Subst) pair.
2470 pub fn instance_mir(self, instance: ty::InstanceDef<'gcx>)
2474 ty::InstanceDef::Item(did) => {
2475 self.optimized_mir(did)
2477 ty::InstanceDef::Intrinsic(..) |
2478 ty::InstanceDef::FnPtrShim(..) |
2479 ty::InstanceDef::Virtual(..) |
2480 ty::InstanceDef::ClosureOnceShim { .. } |
2481 ty::InstanceDef::DropGlue(..) |
2482 ty::InstanceDef::CloneShim(..) => {
2483 self.mir_shims(instance)
2488 /// Given the DefId of an item, returns its MIR, borrowed immutably.
2489 /// Returns None if there is no MIR for the DefId
2490 pub fn maybe_optimized_mir(self, did: DefId) -> Option<&'gcx Mir<'gcx>> {
2491 if self.is_mir_available(did) {
2492 Some(self.optimized_mir(did))
2498 /// Get the attributes of a definition.
2499 pub fn get_attrs(self, did: DefId) -> Attributes<'gcx> {
2500 if let Some(id) = self.hir.as_local_node_id(did) {
2501 Attributes::Borrowed(self.hir.attrs(id))
2503 Attributes::Owned(self.item_attrs(did))
2507 /// Determine whether an item is annotated with an attribute
2508 pub fn has_attr(self, did: DefId, attr: &str) -> bool {
2509 attr::contains_name(&self.get_attrs(did), attr)
2512 /// Returns true if this is an `auto trait`.
2513 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2514 self.trait_def(trait_def_id).has_auto_impl
2517 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
2518 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
2521 /// Given the def_id of an impl, return the def_id of the trait it implements.
2522 /// If it implements no trait, return `None`.
2523 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2524 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2527 /// If the given def ID describes a method belonging to an impl, return the
2528 /// ID of the impl that the method belongs to. Otherwise, return `None`.
2529 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2530 let item = if def_id.krate != LOCAL_CRATE {
2531 if let Some(Def::Method(_)) = self.describe_def(def_id) {
2532 Some(self.associated_item(def_id))
2537 self.opt_associated_item(def_id)
2541 Some(trait_item) => {
2542 match trait_item.container {
2543 TraitContainer(_) => None,
2544 ImplContainer(def_id) => Some(def_id),
2551 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2552 /// with the name of the crate containing the impl.
2553 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2554 if impl_did.is_local() {
2555 let node_id = self.hir.as_local_node_id(impl_did).unwrap();
2556 Ok(self.hir.span(node_id))
2558 Err(self.crate_name(impl_did.krate))
2562 // Hygienically compare a use-site name (`use_name`) for a field or an associated item with its
2563 // supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2564 // definition's parent/scope to perform comparison.
2565 pub fn hygienic_eq(self, use_name: Name, def_name: Name, def_parent_def_id: DefId) -> bool {
2566 self.adjust(use_name, def_parent_def_id, DUMMY_NODE_ID).0 == def_name.to_ident()
2569 pub fn adjust(self, name: Name, scope: DefId, block: NodeId) -> (Ident, DefId) {
2570 self.adjust_ident(name.to_ident(), scope, block)
2573 pub fn adjust_ident(self, mut ident: Ident, scope: DefId, block: NodeId) -> (Ident, DefId) {
2574 let expansion = match scope.krate {
2575 LOCAL_CRATE => self.hir.definitions().expansion(scope.index),
2578 let scope = match ident.ctxt.adjust(expansion) {
2579 Some(macro_def) => self.hir.definitions().macro_def_scope(macro_def),
2580 None if block == DUMMY_NODE_ID => DefId::local(CRATE_DEF_INDEX), // Dummy DefId
2581 None => self.hir.get_module_parent(block),
2587 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
2588 pub fn with_freevars<T, F>(self, fid: NodeId, f: F) -> T where
2589 F: FnOnce(&[hir::Freevar]) -> T,
2591 let def_id = self.hir.local_def_id(fid);
2592 match self.freevars(def_id) {
2599 fn associated_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId)
2602 let id = tcx.hir.as_local_node_id(def_id).unwrap();
2603 let parent_id = tcx.hir.get_parent(id);
2604 let parent_def_id = tcx.hir.local_def_id(parent_id);
2605 let parent_item = tcx.hir.expect_item(parent_id);
2606 match parent_item.node {
2607 hir::ItemImpl(.., ref impl_item_refs) => {
2608 if let Some(impl_item_ref) = impl_item_refs.iter().find(|i| i.id.node_id == id) {
2609 let assoc_item = tcx.associated_item_from_impl_item_ref(parent_def_id,
2611 debug_assert_eq!(assoc_item.def_id, def_id);
2616 hir::ItemTrait(.., ref trait_item_refs) => {
2617 if let Some(trait_item_ref) = trait_item_refs.iter().find(|i| i.id.node_id == id) {
2618 let assoc_item = tcx.associated_item_from_trait_item_ref(parent_def_id,
2621 debug_assert_eq!(assoc_item.def_id, def_id);
2629 span_bug!(parent_item.span,
2630 "unexpected parent of trait or impl item or item not found: {:?}",
2634 /// Calculates the Sized-constraint.
2636 /// In fact, there are only a few options for the types in the constraint:
2637 /// - an obviously-unsized type
2638 /// - a type parameter or projection whose Sizedness can't be known
2639 /// - a tuple of type parameters or projections, if there are multiple
2641 /// - a TyError, if a type contained itself. The representability
2642 /// check should catch this case.
2643 fn adt_sized_constraint<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2645 -> &'tcx [Ty<'tcx>] {
2646 let def = tcx.adt_def(def_id);
2648 let result = tcx.intern_type_list(&def.variants.iter().flat_map(|v| {
2651 def.sized_constraint_for_ty(tcx, tcx.type_of(f.did))
2652 }).collect::<Vec<_>>());
2654 debug!("adt_sized_constraint: {:?} => {:?}", def, result);
2659 fn associated_item_def_ids<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2661 -> Lrc<Vec<DefId>> {
2662 let id = tcx.hir.as_local_node_id(def_id).unwrap();
2663 let item = tcx.hir.expect_item(id);
2664 let vec: Vec<_> = match item.node {
2665 hir::ItemTrait(.., ref trait_item_refs) => {
2666 trait_item_refs.iter()
2667 .map(|trait_item_ref| trait_item_ref.id)
2668 .map(|id| tcx.hir.local_def_id(id.node_id))
2671 hir::ItemImpl(.., ref impl_item_refs) => {
2672 impl_item_refs.iter()
2673 .map(|impl_item_ref| impl_item_ref.id)
2674 .map(|id| tcx.hir.local_def_id(id.node_id))
2677 hir::ItemTraitAlias(..) => vec![],
2678 _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait")
2683 fn def_span<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Span {
2684 tcx.hir.span_if_local(def_id).unwrap()
2687 /// If the given def ID describes an item belonging to a trait,
2688 /// return the ID of the trait that the trait item belongs to.
2689 /// Otherwise, return `None`.
2690 fn trait_of_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Option<DefId> {
2691 tcx.opt_associated_item(def_id)
2692 .and_then(|associated_item| {
2693 match associated_item.container {
2694 TraitContainer(def_id) => Some(def_id),
2695 ImplContainer(_) => None
2700 /// See `ParamEnv` struct def'n for details.
2701 fn param_env<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2704 // Compute the bounds on Self and the type parameters.
2706 let bounds = tcx.predicates_of(def_id).instantiate_identity(tcx);
2707 let predicates = bounds.predicates;
2709 // Finally, we have to normalize the bounds in the environment, in
2710 // case they contain any associated type projections. This process
2711 // can yield errors if the put in illegal associated types, like
2712 // `<i32 as Foo>::Bar` where `i32` does not implement `Foo`. We
2713 // report these errors right here; this doesn't actually feel
2714 // right to me, because constructing the environment feels like a
2715 // kind of a "idempotent" action, but I'm not sure where would be
2716 // a better place. In practice, we construct environments for
2717 // every fn once during type checking, and we'll abort if there
2718 // are any errors at that point, so after type checking you can be
2719 // sure that this will succeed without errors anyway.
2721 let unnormalized_env = ty::ParamEnv::new(tcx.intern_predicates(&predicates),
2722 traits::Reveal::UserFacing,
2723 ty::UniverseIndex::ROOT);
2725 let body_id = tcx.hir.as_local_node_id(def_id).map_or(DUMMY_NODE_ID, |id| {
2726 tcx.hir.maybe_body_owned_by(id).map_or(id, |body| body.node_id)
2728 let cause = traits::ObligationCause::misc(tcx.def_span(def_id), body_id);
2729 traits::normalize_param_env_or_error(tcx, def_id, unnormalized_env, cause)
2732 fn crate_disambiguator<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2733 crate_num: CrateNum) -> CrateDisambiguator {
2734 assert_eq!(crate_num, LOCAL_CRATE);
2735 tcx.sess.local_crate_disambiguator()
2738 fn original_crate_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2739 crate_num: CrateNum) -> Symbol {
2740 assert_eq!(crate_num, LOCAL_CRATE);
2741 tcx.crate_name.clone()
2744 fn crate_hash<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2745 crate_num: CrateNum)
2747 assert_eq!(crate_num, LOCAL_CRATE);
2751 fn instance_def_size_estimate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2752 instance_def: InstanceDef<'tcx>)
2754 match instance_def {
2755 InstanceDef::Item(..) |
2756 InstanceDef::DropGlue(..) => {
2757 let mir = tcx.instance_mir(instance_def);
2758 mir.basic_blocks().iter().map(|bb| bb.statements.len()).sum()
2760 // Estimate the size of other compiler-generated shims to be 1.
2765 pub fn provide(providers: &mut ty::maps::Providers) {
2766 context::provide(providers);
2767 erase_regions::provide(providers);
2768 layout::provide(providers);
2769 util::provide(providers);
2770 *providers = ty::maps::Providers {
2772 associated_item_def_ids,
2773 adt_sized_constraint,
2777 crate_disambiguator,
2778 original_crate_name,
2780 trait_impls_of: trait_def::trait_impls_of_provider,
2781 instance_def_size_estimate,
2786 /// A map for the local crate mapping each type to a vector of its
2787 /// inherent impls. This is not meant to be used outside of coherence;
2788 /// rather, you should request the vector for a specific type via
2789 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2790 /// (constructing this map requires touching the entire crate).
2791 #[derive(Clone, Debug)]
2792 pub struct CrateInherentImpls {
2793 pub inherent_impls: DefIdMap<Lrc<Vec<DefId>>>,
2796 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable)]
2797 pub struct SymbolName {
2798 // FIXME: we don't rely on interning or equality here - better have
2799 // this be a `&'tcx str`.
2800 pub name: InternedString
2803 impl_stable_hash_for!(struct self::SymbolName {
2808 pub fn new(name: &str) -> SymbolName {
2810 name: Symbol::intern(name).as_str()
2815 impl Deref for SymbolName {
2818 fn deref(&self) -> &str { &self.name }
2821 impl fmt::Display for SymbolName {
2822 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2823 fmt::Display::fmt(&self.name, fmt)
2827 impl fmt::Debug for SymbolName {
2828 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2829 fmt::Display::fmt(&self.name, fmt)