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::{Value, PrimVal};
30 use mir::GeneratorLayout;
31 use session::CrateDisambiguator;
34 use ty::subst::{Subst, Substs};
35 use ty::util::IntTypeExt;
36 use ty::walk::TypeWalker;
37 use util::common::ErrorReported;
38 use util::nodemap::{NodeSet, DefIdMap, FxHashMap, FxHashSet};
40 use serialize::{self, Encodable, Encoder};
41 use std::cell::RefCell;
44 use std::hash::{Hash, Hasher};
45 use std::iter::FromIterator;
47 use rustc_data_structures::sync::Lrc;
49 use std::vec::IntoIter;
51 use syntax::ast::{self, DUMMY_NODE_ID, Name, Ident, NodeId};
53 use syntax::ext::hygiene::{Mark, SyntaxContext};
54 use syntax::symbol::{Symbol, InternedString};
55 use syntax_pos::{DUMMY_SP, Span};
56 use rustc_const_math::ConstInt;
58 use rustc_data_structures::accumulate_vec::IntoIter as AccIntoIter;
59 use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
64 pub use self::sty::{Binder, DebruijnIndex};
65 pub use self::sty::{FnSig, GenSig, PolyFnSig, PolyGenSig};
66 pub use self::sty::{InferTy, ParamTy, ProjectionTy, ExistentialPredicate};
67 pub use self::sty::{ClosureSubsts, GeneratorInterior, TypeAndMut};
68 pub use self::sty::{TraitRef, TypeVariants, PolyTraitRef};
69 pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
70 pub use self::sty::{ExistentialProjection, PolyExistentialProjection, Const};
71 pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
72 pub use self::sty::RegionKind;
73 pub use self::sty::{TyVid, IntVid, FloatVid, RegionVid};
74 pub use self::sty::BoundRegion::*;
75 pub use self::sty::InferTy::*;
76 pub use self::sty::RegionKind::*;
77 pub use self::sty::TypeVariants::*;
79 pub use self::binding::BindingMode;
80 pub use self::binding::BindingMode::*;
82 pub use self::context::{TyCtxt, GlobalArenas, AllArenas, tls, keep_local};
83 pub use self::context::{Lift, TypeckTables};
85 pub use self::instance::{Instance, InstanceDef};
87 pub use self::trait_def::TraitDef;
89 pub use self::maps::queries;
100 pub mod inhabitedness;
117 mod structural_impls;
122 /// The complete set of all analyses described in this module. This is
123 /// produced by the driver and fed to trans and later passes.
125 /// NB: These contents are being migrated into queries using the
126 /// *on-demand* infrastructure.
128 pub struct CrateAnalysis {
129 pub access_levels: Lrc<AccessLevels>,
131 pub glob_map: Option<hir::GlobMap>,
135 pub struct Resolutions {
136 pub freevars: FreevarMap,
137 pub trait_map: TraitMap,
138 pub maybe_unused_trait_imports: NodeSet,
139 pub maybe_unused_extern_crates: Vec<(NodeId, Span)>,
140 pub export_map: ExportMap,
143 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
144 pub enum AssociatedItemContainer {
145 TraitContainer(DefId),
146 ImplContainer(DefId),
149 impl AssociatedItemContainer {
150 /// Asserts that this is the def-id of an associated item declared
151 /// in a trait, and returns the trait def-id.
152 pub fn assert_trait(&self) -> DefId {
154 TraitContainer(id) => id,
155 _ => bug!("associated item has wrong container type: {:?}", self)
159 pub fn id(&self) -> DefId {
161 TraitContainer(id) => id,
162 ImplContainer(id) => id,
167 /// The "header" of an impl is everything outside the body: a Self type, a trait
168 /// ref (in the case of a trait impl), and a set of predicates (from the
169 /// bounds/where clauses).
170 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
171 pub struct ImplHeader<'tcx> {
172 pub impl_def_id: DefId,
173 pub self_ty: Ty<'tcx>,
174 pub trait_ref: Option<TraitRef<'tcx>>,
175 pub predicates: Vec<Predicate<'tcx>>,
178 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
179 pub struct AssociatedItem {
182 pub kind: AssociatedKind,
184 pub defaultness: hir::Defaultness,
185 pub container: AssociatedItemContainer,
187 /// Whether this is a method with an explicit self
188 /// as its first argument, allowing method calls.
189 pub method_has_self_argument: bool,
192 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash, RustcEncodable, RustcDecodable)]
193 pub enum AssociatedKind {
199 impl AssociatedItem {
200 pub fn def(&self) -> Def {
202 AssociatedKind::Const => Def::AssociatedConst(self.def_id),
203 AssociatedKind::Method => Def::Method(self.def_id),
204 AssociatedKind::Type => Def::AssociatedTy(self.def_id),
208 /// Tests whether the associated item admits a non-trivial implementation
210 pub fn relevant_for_never<'tcx>(&self) -> bool {
212 AssociatedKind::Const => true,
213 AssociatedKind::Type => true,
214 // FIXME(canndrew): Be more thorough here, check if any argument is uninhabited.
215 AssociatedKind::Method => !self.method_has_self_argument,
219 pub fn signature<'a, 'tcx>(&self, tcx: &TyCtxt<'a, 'tcx, 'tcx>) -> String {
221 ty::AssociatedKind::Method => {
222 // We skip the binder here because the binder would deanonymize all
223 // late-bound regions, and we don't want method signatures to show up
224 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
225 // regions just fine, showing `fn(&MyType)`.
226 format!("{}", tcx.fn_sig(self.def_id).skip_binder())
228 ty::AssociatedKind::Type => format!("type {};", self.name.to_string()),
229 ty::AssociatedKind::Const => {
230 format!("const {}: {:?};", self.name.to_string(), tcx.type_of(self.def_id))
236 #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable)]
237 pub enum Visibility {
238 /// Visible everywhere (including in other crates).
240 /// Visible only in the given crate-local module.
242 /// Not visible anywhere in the local crate. This is the visibility of private external items.
246 pub trait DefIdTree: Copy {
247 fn parent(self, id: DefId) -> Option<DefId>;
249 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
250 if descendant.krate != ancestor.krate {
254 while descendant != ancestor {
255 match self.parent(descendant) {
256 Some(parent) => descendant = parent,
257 None => return false,
264 impl<'a, 'gcx, 'tcx> DefIdTree for TyCtxt<'a, 'gcx, 'tcx> {
265 fn parent(self, id: DefId) -> Option<DefId> {
266 self.def_key(id).parent.map(|index| DefId { index: index, ..id })
271 pub fn from_hir(visibility: &hir::Visibility, id: NodeId, tcx: TyCtxt) -> Self {
273 hir::Public => Visibility::Public,
274 hir::Visibility::Crate => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
275 hir::Visibility::Restricted { ref path, .. } => match path.def {
276 // If there is no resolution, `resolve` will have already reported an error, so
277 // assume that the visibility is public to avoid reporting more privacy errors.
278 Def::Err => Visibility::Public,
279 def => Visibility::Restricted(def.def_id()),
282 Visibility::Restricted(tcx.hir.get_module_parent(id))
287 /// Returns true if an item with this visibility is accessible from the given block.
288 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
289 let restriction = match self {
290 // Public items are visible everywhere.
291 Visibility::Public => return true,
292 // Private items from other crates are visible nowhere.
293 Visibility::Invisible => return false,
294 // Restricted items are visible in an arbitrary local module.
295 Visibility::Restricted(other) if other.krate != module.krate => return false,
296 Visibility::Restricted(module) => module,
299 tree.is_descendant_of(module, restriction)
302 /// Returns true if this visibility is at least as accessible as the given visibility
303 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
304 let vis_restriction = match vis {
305 Visibility::Public => return self == Visibility::Public,
306 Visibility::Invisible => return true,
307 Visibility::Restricted(module) => module,
310 self.is_accessible_from(vis_restriction, tree)
313 // Returns true if this item is visible anywhere in the local crate.
314 pub fn is_visible_locally(self) -> bool {
316 Visibility::Public => true,
317 Visibility::Restricted(def_id) => def_id.is_local(),
318 Visibility::Invisible => false,
323 #[derive(Clone, PartialEq, RustcDecodable, RustcEncodable, Copy)]
325 Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
326 Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
327 Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
328 Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
331 /// The crate variances map is computed during typeck and contains the
332 /// variance of every item in the local crate. You should not use it
333 /// directly, because to do so will make your pass dependent on the
334 /// HIR of every item in the local crate. Instead, use
335 /// `tcx.variances_of()` to get the variance for a *particular*
337 pub struct CrateVariancesMap {
338 /// For each item with generics, maps to a vector of the variance
339 /// of its generics. If an item has no generics, it will have no
341 pub variances: FxHashMap<DefId, Lrc<Vec<ty::Variance>>>,
343 /// An empty vector, useful for cloning.
344 pub empty_variance: Lrc<Vec<ty::Variance>>,
348 /// `a.xform(b)` combines the variance of a context with the
349 /// variance of a type with the following meaning. If we are in a
350 /// context with variance `a`, and we encounter a type argument in
351 /// a position with variance `b`, then `a.xform(b)` is the new
352 /// variance with which the argument appears.
358 /// Here, the "ambient" variance starts as covariant. `*mut T` is
359 /// invariant with respect to `T`, so the variance in which the
360 /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which
361 /// yields `Invariant`. Now, the type `Vec<T>` is covariant with
362 /// respect to its type argument `T`, and hence the variance of
363 /// the `i32` here is `Invariant.xform(Covariant)`, which results
364 /// (again) in `Invariant`.
368 /// fn(*const Vec<i32>, *mut Vec<i32)
370 /// The ambient variance is covariant. A `fn` type is
371 /// contravariant with respect to its parameters, so the variance
372 /// within which both pointer types appear is
373 /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const
374 /// T` is covariant with respect to `T`, so the variance within
375 /// which the first `Vec<i32>` appears is
376 /// `Contravariant.xform(Covariant)` or `Contravariant`. The same
377 /// is true for its `i32` argument. In the `*mut T` case, the
378 /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`,
379 /// and hence the outermost type is `Invariant` with respect to
380 /// `Vec<i32>` (and its `i32` argument).
382 /// Source: Figure 1 of "Taming the Wildcards:
383 /// Combining Definition- and Use-Site Variance" published in PLDI'11.
384 pub fn xform(self, v: ty::Variance) -> ty::Variance {
386 // Figure 1, column 1.
387 (ty::Covariant, ty::Covariant) => ty::Covariant,
388 (ty::Covariant, ty::Contravariant) => ty::Contravariant,
389 (ty::Covariant, ty::Invariant) => ty::Invariant,
390 (ty::Covariant, ty::Bivariant) => ty::Bivariant,
392 // Figure 1, column 2.
393 (ty::Contravariant, ty::Covariant) => ty::Contravariant,
394 (ty::Contravariant, ty::Contravariant) => ty::Covariant,
395 (ty::Contravariant, ty::Invariant) => ty::Invariant,
396 (ty::Contravariant, ty::Bivariant) => ty::Bivariant,
398 // Figure 1, column 3.
399 (ty::Invariant, _) => ty::Invariant,
401 // Figure 1, column 4.
402 (ty::Bivariant, _) => ty::Bivariant,
407 // Contains information needed to resolve types and (in the future) look up
408 // the types of AST nodes.
409 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
410 pub struct CReaderCacheKey {
415 // Flags that we track on types. These flags are propagated upwards
416 // through the type during type construction, so that we can quickly
417 // check whether the type has various kinds of types in it without
418 // recursing over the type itself.
420 pub struct TypeFlags: u32 {
421 const HAS_PARAMS = 1 << 0;
422 const HAS_SELF = 1 << 1;
423 const HAS_TY_INFER = 1 << 2;
424 const HAS_RE_INFER = 1 << 3;
425 const HAS_RE_SKOL = 1 << 4;
427 /// Does this have any `ReEarlyBound` regions? Used to
428 /// determine whether substitition is required, since those
429 /// represent regions that are bound in a `ty::Generics` and
430 /// hence may be substituted.
431 const HAS_RE_EARLY_BOUND = 1 << 5;
433 /// Does this have any region that "appears free" in the type?
434 /// Basically anything but `ReLateBound` and `ReErased`.
435 const HAS_FREE_REGIONS = 1 << 6;
437 /// Is an error type reachable?
438 const HAS_TY_ERR = 1 << 7;
439 const HAS_PROJECTION = 1 << 8;
441 // FIXME: Rename this to the actual property since it's used for generators too
442 const HAS_TY_CLOSURE = 1 << 9;
444 // true if there are "names" of types and regions and so forth
445 // that are local to a particular fn
446 const HAS_LOCAL_NAMES = 1 << 10;
448 // Present if the type belongs in a local type context.
449 // Only set for TyInfer other than Fresh.
450 const KEEP_IN_LOCAL_TCX = 1 << 11;
452 // Is there a projection that does not involve a bound region?
453 // Currently we can't normalize projections w/ bound regions.
454 const HAS_NORMALIZABLE_PROJECTION = 1 << 12;
456 const NEEDS_SUBST = TypeFlags::HAS_PARAMS.bits |
457 TypeFlags::HAS_SELF.bits |
458 TypeFlags::HAS_RE_EARLY_BOUND.bits;
460 // Flags representing the nominal content of a type,
461 // computed by FlagsComputation. If you add a new nominal
462 // flag, it should be added here too.
463 const NOMINAL_FLAGS = TypeFlags::HAS_PARAMS.bits |
464 TypeFlags::HAS_SELF.bits |
465 TypeFlags::HAS_TY_INFER.bits |
466 TypeFlags::HAS_RE_INFER.bits |
467 TypeFlags::HAS_RE_SKOL.bits |
468 TypeFlags::HAS_RE_EARLY_BOUND.bits |
469 TypeFlags::HAS_FREE_REGIONS.bits |
470 TypeFlags::HAS_TY_ERR.bits |
471 TypeFlags::HAS_PROJECTION.bits |
472 TypeFlags::HAS_TY_CLOSURE.bits |
473 TypeFlags::HAS_LOCAL_NAMES.bits |
474 TypeFlags::KEEP_IN_LOCAL_TCX.bits;
478 pub struct TyS<'tcx> {
479 pub sty: TypeVariants<'tcx>,
480 pub flags: TypeFlags,
482 // the maximal depth of any bound regions appearing in this type.
486 impl<'tcx> PartialEq for TyS<'tcx> {
488 fn eq(&self, other: &TyS<'tcx>) -> bool {
489 // (self as *const _) == (other as *const _)
490 (self as *const TyS<'tcx>) == (other as *const TyS<'tcx>)
493 impl<'tcx> Eq for TyS<'tcx> {}
495 impl<'tcx> Hash for TyS<'tcx> {
496 fn hash<H: Hasher>(&self, s: &mut H) {
497 (self as *const TyS).hash(s)
501 impl<'tcx> TyS<'tcx> {
502 pub fn is_primitive_ty(&self) -> bool {
504 TypeVariants::TyBool |
505 TypeVariants::TyChar |
506 TypeVariants::TyInt(_) |
507 TypeVariants::TyUint(_) |
508 TypeVariants::TyFloat(_) |
509 TypeVariants::TyInfer(InferTy::IntVar(_)) |
510 TypeVariants::TyInfer(InferTy::FloatVar(_)) |
511 TypeVariants::TyInfer(InferTy::FreshIntTy(_)) |
512 TypeVariants::TyInfer(InferTy::FreshFloatTy(_)) => true,
513 TypeVariants::TyRef(_, x) => x.ty.is_primitive_ty(),
518 pub fn is_suggestable(&self) -> bool {
520 TypeVariants::TyAnon(..) |
521 TypeVariants::TyFnDef(..) |
522 TypeVariants::TyFnPtr(..) |
523 TypeVariants::TyDynamic(..) |
524 TypeVariants::TyClosure(..) |
525 TypeVariants::TyInfer(..) |
526 TypeVariants::TyProjection(..) => false,
532 impl<'gcx> HashStable<StableHashingContext<'gcx>> for ty::TyS<'gcx> {
533 fn hash_stable<W: StableHasherResult>(&self,
534 hcx: &mut StableHashingContext<'gcx>,
535 hasher: &mut StableHasher<W>) {
539 // The other fields just provide fast access to information that is
540 // also contained in `sty`, so no need to hash them.
545 sty.hash_stable(hcx, hasher);
549 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
551 impl<'tcx> serialize::UseSpecializedEncodable for Ty<'tcx> {}
552 impl<'tcx> serialize::UseSpecializedDecodable for Ty<'tcx> {}
554 /// A wrapper for slices with the additional invariant
555 /// that the slice is interned and no other slice with
556 /// the same contents can exist in the same context.
557 /// This means we can use pointer + length for both
558 /// equality comparisons and hashing.
559 #[derive(Debug, RustcEncodable)]
560 pub struct Slice<T>([T]);
562 impl<T> PartialEq for Slice<T> {
564 fn eq(&self, other: &Slice<T>) -> bool {
565 (&self.0 as *const [T]) == (&other.0 as *const [T])
568 impl<T> Eq for Slice<T> {}
570 impl<T> Hash for Slice<T> {
571 fn hash<H: Hasher>(&self, s: &mut H) {
572 (self.as_ptr(), self.len()).hash(s)
576 impl<T> Deref for Slice<T> {
578 fn deref(&self) -> &[T] {
583 impl<'a, T> IntoIterator for &'a Slice<T> {
585 type IntoIter = <&'a [T] as IntoIterator>::IntoIter;
586 fn into_iter(self) -> Self::IntoIter {
591 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Slice<Ty<'tcx>> {}
594 pub fn empty<'a>() -> &'a Slice<T> {
596 mem::transmute(slice::from_raw_parts(0x1 as *const T, 0))
601 /// Upvars do not get their own node-id. Instead, we use the pair of
602 /// the original var id (that is, the root variable that is referenced
603 /// by the upvar) and the id of the closure expression.
604 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
606 pub var_id: hir::HirId,
607 pub closure_expr_id: LocalDefId,
610 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, Copy)]
611 pub enum BorrowKind {
612 /// Data must be immutable and is aliasable.
615 /// Data must be immutable but not aliasable. This kind of borrow
616 /// cannot currently be expressed by the user and is used only in
617 /// implicit closure bindings. It is needed when the closure
618 /// is borrowing or mutating a mutable referent, e.g.:
620 /// let x: &mut isize = ...;
621 /// let y = || *x += 5;
623 /// If we were to try to translate this closure into a more explicit
624 /// form, we'd encounter an error with the code as written:
626 /// struct Env { x: & &mut isize }
627 /// let x: &mut isize = ...;
628 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
629 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
631 /// This is then illegal because you cannot mutate a `&mut` found
632 /// in an aliasable location. To solve, you'd have to translate with
633 /// an `&mut` borrow:
635 /// struct Env { x: & &mut isize }
636 /// let x: &mut isize = ...;
637 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
638 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
640 /// Now the assignment to `**env.x` is legal, but creating a
641 /// mutable pointer to `x` is not because `x` is not mutable. We
642 /// could fix this by declaring `x` as `let mut x`. This is ok in
643 /// user code, if awkward, but extra weird for closures, since the
644 /// borrow is hidden.
646 /// So we introduce a "unique imm" borrow -- the referent is
647 /// immutable, but not aliasable. This solves the problem. For
648 /// simplicity, we don't give users the way to express this
649 /// borrow, it's just used when translating closures.
652 /// Data is mutable and not aliasable.
656 /// Information describing the capture of an upvar. This is computed
657 /// during `typeck`, specifically by `regionck`.
658 #[derive(PartialEq, Clone, Debug, Copy, RustcEncodable, RustcDecodable)]
659 pub enum UpvarCapture<'tcx> {
660 /// Upvar is captured by value. This is always true when the
661 /// closure is labeled `move`, but can also be true in other cases
662 /// depending on inference.
665 /// Upvar is captured by reference.
666 ByRef(UpvarBorrow<'tcx>),
669 #[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable)]
670 pub struct UpvarBorrow<'tcx> {
671 /// The kind of borrow: by-ref upvars have access to shared
672 /// immutable borrows, which are not part of the normal language
674 pub kind: BorrowKind,
676 /// Region of the resulting reference.
677 pub region: ty::Region<'tcx>,
680 pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
682 #[derive(Copy, Clone)]
683 pub struct ClosureUpvar<'tcx> {
689 #[derive(Clone, Copy, PartialEq, Eq)]
690 pub enum IntVarValue {
692 UintType(ast::UintTy),
695 #[derive(Clone, Copy, PartialEq, Eq)]
696 pub struct FloatVarValue(pub ast::FloatTy);
698 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
699 pub struct TypeParameterDef {
703 pub has_default: bool,
704 pub object_lifetime_default: ObjectLifetimeDefault,
706 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
707 /// on generic parameter `T`, asserts data behind the parameter
708 /// `T` won't be accessed during the parent type's `Drop` impl.
709 pub pure_wrt_drop: bool,
711 pub synthetic: Option<hir::SyntheticTyParamKind>,
714 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
715 pub struct RegionParameterDef {
720 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
721 /// on generic parameter `'a`, asserts data of lifetime `'a`
722 /// won't be accessed during the parent type's `Drop` impl.
723 pub pure_wrt_drop: bool,
726 impl RegionParameterDef {
727 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
728 ty::EarlyBoundRegion {
735 pub fn to_bound_region(&self) -> ty::BoundRegion {
736 self.to_early_bound_region_data().to_bound_region()
740 impl ty::EarlyBoundRegion {
741 pub fn to_bound_region(&self) -> ty::BoundRegion {
742 ty::BoundRegion::BrNamed(self.def_id, self.name)
746 /// Information about the formal type/lifetime parameters associated
747 /// with an item or method. Analogous to hir::Generics.
749 /// Note that in the presence of a `Self` parameter, the ordering here
750 /// is different from the ordering in a Substs. Substs are ordered as
751 /// Self, *Regions, *Other Type Params, (...child generics)
752 /// while this struct is ordered as
753 /// regions = Regions
754 /// types = [Self, *Other Type Params]
755 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
756 pub struct Generics {
757 pub parent: Option<DefId>,
758 pub parent_regions: u32,
759 pub parent_types: u32,
760 pub regions: Vec<RegionParameterDef>,
761 pub types: Vec<TypeParameterDef>,
763 /// Reverse map to each `TypeParameterDef`'s `index` field
764 pub type_param_to_index: FxHashMap<DefId, u32>,
767 pub has_late_bound_regions: Option<Span>,
770 impl<'a, 'gcx, 'tcx> Generics {
771 pub fn parent_count(&self) -> usize {
772 self.parent_regions as usize + self.parent_types as usize
775 pub fn own_count(&self) -> usize {
776 self.regions.len() + self.types.len()
779 pub fn count(&self) -> usize {
780 self.parent_count() + self.own_count()
783 pub fn region_param(&'tcx self,
784 param: &EarlyBoundRegion,
785 tcx: TyCtxt<'a, 'gcx, 'tcx>)
786 -> &'tcx RegionParameterDef
788 if let Some(index) = param.index.checked_sub(self.parent_count() as u32) {
789 &self.regions[index as usize - self.has_self as usize]
791 tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
792 .region_param(param, tcx)
796 /// Returns the `TypeParameterDef` associated with this `ParamTy`.
797 pub fn type_param(&'tcx self,
799 tcx: TyCtxt<'a, 'gcx, 'tcx>)
800 -> &TypeParameterDef {
801 if let Some(idx) = param.idx.checked_sub(self.parent_count() as u32) {
802 // non-Self type parameters are always offset by exactly
803 // `self.regions.len()`. In the absence of a Self, this is obvious,
804 // but even in the presence of a `Self` we just have to "compensate"
807 // Without a `Self` (or in a nested generics that doesn't have
808 // a `Self` in itself, even through it parent does), for example
809 // for `fn foo<'a, T1, T2>()`, the situation is:
817 // And with a `Self`, for example for `trait Foo<'a, 'b, T1, T2>`, the
826 // And it can be seen that in both cases, to move from a substs
827 // offset to a generics offset you just have to offset by the
828 // number of regions.
829 let type_param_offset = self.regions.len();
831 let has_self = self.has_self && self.parent.is_none();
832 let is_separated_self = type_param_offset != 0 && idx == 0 && has_self;
834 if let Some(idx) = (idx as usize).checked_sub(type_param_offset) {
835 assert!(!is_separated_self, "found a Self after type_param_offset");
838 assert!(is_separated_self, "non-Self param before type_param_offset");
842 tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
843 .type_param(param, tcx)
848 /// Bounds on generics.
849 #[derive(Clone, Default)]
850 pub struct GenericPredicates<'tcx> {
851 pub parent: Option<DefId>,
852 pub predicates: Vec<Predicate<'tcx>>,
855 impl<'tcx> serialize::UseSpecializedEncodable for GenericPredicates<'tcx> {}
856 impl<'tcx> serialize::UseSpecializedDecodable for GenericPredicates<'tcx> {}
858 impl<'a, 'gcx, 'tcx> GenericPredicates<'tcx> {
859 pub fn instantiate(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>)
860 -> InstantiatedPredicates<'tcx> {
861 let mut instantiated = InstantiatedPredicates::empty();
862 self.instantiate_into(tcx, &mut instantiated, substs);
865 pub fn instantiate_own(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>)
866 -> InstantiatedPredicates<'tcx> {
867 InstantiatedPredicates {
868 predicates: self.predicates.subst(tcx, substs)
872 fn instantiate_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
873 instantiated: &mut InstantiatedPredicates<'tcx>,
874 substs: &Substs<'tcx>) {
875 if let Some(def_id) = self.parent {
876 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
878 instantiated.predicates.extend(self.predicates.iter().map(|p| p.subst(tcx, substs)))
881 pub fn instantiate_identity(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>)
882 -> InstantiatedPredicates<'tcx> {
883 let mut instantiated = InstantiatedPredicates::empty();
884 self.instantiate_identity_into(tcx, &mut instantiated);
888 fn instantiate_identity_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
889 instantiated: &mut InstantiatedPredicates<'tcx>) {
890 if let Some(def_id) = self.parent {
891 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
893 instantiated.predicates.extend(&self.predicates)
896 pub fn instantiate_supertrait(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
897 poly_trait_ref: &ty::PolyTraitRef<'tcx>)
898 -> InstantiatedPredicates<'tcx>
900 assert_eq!(self.parent, None);
901 InstantiatedPredicates {
902 predicates: self.predicates.iter().map(|pred| {
903 pred.subst_supertrait(tcx, poly_trait_ref)
909 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
910 pub enum Predicate<'tcx> {
911 /// Corresponds to `where Foo : Bar<A,B,C>`. `Foo` here would be
912 /// the `Self` type of the trait reference and `A`, `B`, and `C`
913 /// would be the type parameters.
914 Trait(PolyTraitPredicate<'tcx>),
917 RegionOutlives(PolyRegionOutlivesPredicate<'tcx>),
920 TypeOutlives(PolyTypeOutlivesPredicate<'tcx>),
922 /// where <T as TraitRef>::Name == X, approximately.
923 /// See `ProjectionPredicate` struct for details.
924 Projection(PolyProjectionPredicate<'tcx>),
927 WellFormed(Ty<'tcx>),
929 /// trait must be object-safe
932 /// No direct syntax. May be thought of as `where T : FnFoo<...>`
933 /// for some substitutions `...` and T being a closure type.
934 /// Satisfied (or refuted) once we know the closure's kind.
935 ClosureKind(DefId, ClosureSubsts<'tcx>, ClosureKind),
938 Subtype(PolySubtypePredicate<'tcx>),
940 /// Constant initializer must evaluate successfully.
941 ConstEvaluatable(DefId, &'tcx Substs<'tcx>),
944 impl<'tcx> AsRef<Predicate<'tcx>> for Predicate<'tcx> {
945 fn as_ref(&self) -> &Predicate<'tcx> {
950 impl<'a, 'gcx, 'tcx> Predicate<'tcx> {
951 /// Performs a substitution suitable for going from a
952 /// poly-trait-ref to supertraits that must hold if that
953 /// poly-trait-ref holds. This is slightly different from a normal
954 /// substitution in terms of what happens with bound regions. See
955 /// lengthy comment below for details.
956 pub fn subst_supertrait(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
957 trait_ref: &ty::PolyTraitRef<'tcx>)
958 -> ty::Predicate<'tcx>
960 // The interaction between HRTB and supertraits is not entirely
961 // obvious. Let me walk you (and myself) through an example.
963 // Let's start with an easy case. Consider two traits:
965 // trait Foo<'a> : Bar<'a,'a> { }
966 // trait Bar<'b,'c> { }
968 // Now, if we have a trait reference `for<'x> T : Foo<'x>`, then
969 // we can deduce that `for<'x> T : Bar<'x,'x>`. Basically, if we
970 // knew that `Foo<'x>` (for any 'x) then we also know that
971 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
972 // normal substitution.
974 // In terms of why this is sound, the idea is that whenever there
975 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
976 // holds. So if there is an impl of `T:Foo<'a>` that applies to
977 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
980 // Another example to be careful of is this:
982 // trait Foo1<'a> : for<'b> Bar1<'a,'b> { }
983 // trait Bar1<'b,'c> { }
985 // Here, if we have `for<'x> T : Foo1<'x>`, then what do we know?
986 // The answer is that we know `for<'x,'b> T : Bar1<'x,'b>`. The
987 // reason is similar to the previous example: any impl of
988 // `T:Foo1<'x>` must show that `for<'b> T : Bar1<'x, 'b>`. So
989 // basically we would want to collapse the bound lifetimes from
990 // the input (`trait_ref`) and the supertraits.
992 // To achieve this in practice is fairly straightforward. Let's
993 // consider the more complicated scenario:
995 // - We start out with `for<'x> T : Foo1<'x>`. In this case, `'x`
996 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T : Bar1<'x,'b>`,
997 // where both `'x` and `'b` would have a DB index of 1.
998 // The substitution from the input trait-ref is therefore going to be
999 // `'a => 'x` (where `'x` has a DB index of 1).
1000 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1001 // early-bound parameter and `'b' is a late-bound parameter with a
1003 // - If we replace `'a` with `'x` from the input, it too will have
1004 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1005 // just as we wanted.
1007 // There is only one catch. If we just apply the substitution `'a
1008 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1009 // adjust the DB index because we substituting into a binder (it
1010 // tries to be so smart...) resulting in `for<'x> for<'b>
1011 // Bar1<'x,'b>` (we have no syntax for this, so use your
1012 // imagination). Basically the 'x will have DB index of 2 and 'b
1013 // will have DB index of 1. Not quite what we want. So we apply
1014 // the substitution to the *contents* of the trait reference,
1015 // rather than the trait reference itself (put another way, the
1016 // substitution code expects equal binding levels in the values
1017 // from the substitution and the value being substituted into, and
1018 // this trick achieves that).
1020 let substs = &trait_ref.0.substs;
1022 Predicate::Trait(ty::Binder(ref data)) =>
1023 Predicate::Trait(ty::Binder(data.subst(tcx, substs))),
1024 Predicate::Subtype(ty::Binder(ref data)) =>
1025 Predicate::Subtype(ty::Binder(data.subst(tcx, substs))),
1026 Predicate::RegionOutlives(ty::Binder(ref data)) =>
1027 Predicate::RegionOutlives(ty::Binder(data.subst(tcx, substs))),
1028 Predicate::TypeOutlives(ty::Binder(ref data)) =>
1029 Predicate::TypeOutlives(ty::Binder(data.subst(tcx, substs))),
1030 Predicate::Projection(ty::Binder(ref data)) =>
1031 Predicate::Projection(ty::Binder(data.subst(tcx, substs))),
1032 Predicate::WellFormed(data) =>
1033 Predicate::WellFormed(data.subst(tcx, substs)),
1034 Predicate::ObjectSafe(trait_def_id) =>
1035 Predicate::ObjectSafe(trait_def_id),
1036 Predicate::ClosureKind(closure_def_id, closure_substs, kind) =>
1037 Predicate::ClosureKind(closure_def_id, closure_substs.subst(tcx, substs), kind),
1038 Predicate::ConstEvaluatable(def_id, const_substs) =>
1039 Predicate::ConstEvaluatable(def_id, const_substs.subst(tcx, substs)),
1044 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1045 pub struct TraitPredicate<'tcx> {
1046 pub trait_ref: TraitRef<'tcx>
1048 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1050 impl<'tcx> TraitPredicate<'tcx> {
1051 pub fn def_id(&self) -> DefId {
1052 self.trait_ref.def_id
1055 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
1056 self.trait_ref.input_types()
1059 pub fn self_ty(&self) -> Ty<'tcx> {
1060 self.trait_ref.self_ty()
1064 impl<'tcx> PolyTraitPredicate<'tcx> {
1065 pub fn def_id(&self) -> DefId {
1066 // ok to skip binder since trait def-id does not care about regions
1071 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1072 pub struct OutlivesPredicate<A,B>(pub A, pub B); // `A : B`
1073 pub type PolyOutlivesPredicate<A,B> = ty::Binder<OutlivesPredicate<A,B>>;
1074 pub type PolyRegionOutlivesPredicate<'tcx> = PolyOutlivesPredicate<ty::Region<'tcx>,
1076 pub type PolyTypeOutlivesPredicate<'tcx> = PolyOutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1078 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1079 pub struct SubtypePredicate<'tcx> {
1080 pub a_is_expected: bool,
1084 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1086 /// This kind of predicate has no *direct* correspondent in the
1087 /// syntax, but it roughly corresponds to the syntactic forms:
1089 /// 1. `T : TraitRef<..., Item=Type>`
1090 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1092 /// In particular, form #1 is "desugared" to the combination of a
1093 /// normal trait predicate (`T : TraitRef<...>`) and one of these
1094 /// predicates. Form #2 is a broader form in that it also permits
1095 /// equality between arbitrary types. Processing an instance of
1096 /// Form #2 eventually yields one of these `ProjectionPredicate`
1097 /// instances to normalize the LHS.
1098 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1099 pub struct ProjectionPredicate<'tcx> {
1100 pub projection_ty: ProjectionTy<'tcx>,
1104 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1106 impl<'tcx> PolyProjectionPredicate<'tcx> {
1107 pub fn to_poly_trait_ref(&self, tcx: TyCtxt) -> PolyTraitRef<'tcx> {
1108 // Note: unlike with TraitRef::to_poly_trait_ref(),
1109 // self.0.trait_ref is permitted to have escaping regions.
1110 // This is because here `self` has a `Binder` and so does our
1111 // return value, so we are preserving the number of binding
1113 ty::Binder(self.0.projection_ty.trait_ref(tcx))
1116 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1117 Binder(self.skip_binder().ty) // preserves binding levels
1121 pub trait ToPolyTraitRef<'tcx> {
1122 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1125 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1126 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1127 assert!(!self.has_escaping_regions());
1128 ty::Binder(self.clone())
1132 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1133 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1134 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1138 pub trait ToPredicate<'tcx> {
1139 fn to_predicate(&self) -> Predicate<'tcx>;
1142 impl<'tcx> ToPredicate<'tcx> for TraitRef<'tcx> {
1143 fn to_predicate(&self) -> Predicate<'tcx> {
1144 // we're about to add a binder, so let's check that we don't
1145 // accidentally capture anything, or else that might be some
1146 // weird debruijn accounting.
1147 assert!(!self.has_escaping_regions());
1149 ty::Predicate::Trait(ty::Binder(ty::TraitPredicate {
1150 trait_ref: self.clone()
1155 impl<'tcx> ToPredicate<'tcx> for PolyTraitRef<'tcx> {
1156 fn to_predicate(&self) -> Predicate<'tcx> {
1157 ty::Predicate::Trait(self.to_poly_trait_predicate())
1161 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1162 fn to_predicate(&self) -> Predicate<'tcx> {
1163 Predicate::RegionOutlives(self.clone())
1167 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1168 fn to_predicate(&self) -> Predicate<'tcx> {
1169 Predicate::TypeOutlives(self.clone())
1173 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1174 fn to_predicate(&self) -> Predicate<'tcx> {
1175 Predicate::Projection(self.clone())
1179 impl<'tcx> Predicate<'tcx> {
1180 /// Iterates over the types in this predicate. Note that in all
1181 /// cases this is skipping over a binder, so late-bound regions
1182 /// with depth 0 are bound by the predicate.
1183 pub fn walk_tys(&self) -> IntoIter<Ty<'tcx>> {
1184 let vec: Vec<_> = match *self {
1185 ty::Predicate::Trait(ref data) => {
1186 data.skip_binder().input_types().collect()
1188 ty::Predicate::Subtype(ty::Binder(SubtypePredicate { a, b, a_is_expected: _ })) => {
1191 ty::Predicate::TypeOutlives(ty::Binder(ref data)) => {
1194 ty::Predicate::RegionOutlives(..) => {
1197 ty::Predicate::Projection(ref data) => {
1198 data.0.projection_ty.substs.types().chain(Some(data.0.ty)).collect()
1200 ty::Predicate::WellFormed(data) => {
1203 ty::Predicate::ObjectSafe(_trait_def_id) => {
1206 ty::Predicate::ClosureKind(_closure_def_id, closure_substs, _kind) => {
1207 closure_substs.substs.types().collect()
1209 ty::Predicate::ConstEvaluatable(_, substs) => {
1210 substs.types().collect()
1214 // The only reason to collect into a vector here is that I was
1215 // too lazy to make the full (somewhat complicated) iterator
1216 // type that would be needed here. But I wanted this fn to
1217 // return an iterator conceptually, rather than a `Vec`, so as
1218 // to be closer to `Ty::walk`.
1222 pub fn to_opt_poly_trait_ref(&self) -> Option<PolyTraitRef<'tcx>> {
1224 Predicate::Trait(ref t) => {
1225 Some(t.to_poly_trait_ref())
1227 Predicate::Projection(..) |
1228 Predicate::Subtype(..) |
1229 Predicate::RegionOutlives(..) |
1230 Predicate::WellFormed(..) |
1231 Predicate::ObjectSafe(..) |
1232 Predicate::ClosureKind(..) |
1233 Predicate::TypeOutlives(..) |
1234 Predicate::ConstEvaluatable(..) => {
1240 pub fn to_opt_type_outlives(&self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1242 Predicate::TypeOutlives(data) => {
1245 Predicate::Trait(..) |
1246 Predicate::Projection(..) |
1247 Predicate::Subtype(..) |
1248 Predicate::RegionOutlives(..) |
1249 Predicate::WellFormed(..) |
1250 Predicate::ObjectSafe(..) |
1251 Predicate::ClosureKind(..) |
1252 Predicate::ConstEvaluatable(..) => {
1259 /// Represents the bounds declared on a particular set of type
1260 /// parameters. Should eventually be generalized into a flag list of
1261 /// where clauses. You can obtain a `InstantiatedPredicates` list from a
1262 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1263 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1264 /// the `GenericPredicates` are expressed in terms of the bound type
1265 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1266 /// represented a set of bounds for some particular instantiation,
1267 /// meaning that the generic parameters have been substituted with
1272 /// struct Foo<T,U:Bar<T>> { ... }
1274 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1275 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1276 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1277 /// [usize:Bar<isize>]]`.
1279 pub struct InstantiatedPredicates<'tcx> {
1280 pub predicates: Vec<Predicate<'tcx>>,
1283 impl<'tcx> InstantiatedPredicates<'tcx> {
1284 pub fn empty() -> InstantiatedPredicates<'tcx> {
1285 InstantiatedPredicates { predicates: vec![] }
1288 pub fn is_empty(&self) -> bool {
1289 self.predicates.is_empty()
1293 /// "Universes" are used during type- and trait-checking in the
1294 /// presence of `for<..>` binders to control what sets of names are
1295 /// visible. Universes are arranged into a tree: the root universe
1296 /// contains names that are always visible. But when you enter into
1297 /// some subuniverse, then it may add names that are only visible
1298 /// within that subtree (but it can still name the names of its
1299 /// ancestor universes).
1301 /// To make this more concrete, consider this program:
1305 /// fn bar<T>(x: T) {
1306 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1310 /// The struct name `Foo` is in the root universe U0. But the type
1311 /// parameter `T`, introduced on `bar`, is in a subuniverse U1 --
1312 /// i.e., within `bar`, we can name both `T` and `Foo`, but outside of
1313 /// `bar`, we cannot name `T`. Then, within the type of `y`, the
1314 /// region `'a` is in a subuniverse U2 of U1, because we can name it
1315 /// inside the fn type but not outside.
1317 /// Universes are related to **skolemization** -- which is a way of
1318 /// doing type- and trait-checking around these "forall" binders (also
1319 /// called **universal quantification**). The idea is that when, in
1320 /// the body of `bar`, we refer to `T` as a type, we aren't referring
1321 /// to any type in particular, but rather a kind of "fresh" type that
1322 /// is distinct from all other types we have actually declared. This
1323 /// is called a **skolemized** type, and we use universes to talk
1324 /// about this. In other words, a type name in universe 0 always
1325 /// corresponds to some "ground" type that the user declared, but a
1326 /// type name in a non-zero universe is a skolemized type -- an
1327 /// idealized representative of "types in general" that we use for
1328 /// checking generic functions.
1329 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1330 pub struct UniverseIndex(u32);
1332 impl UniverseIndex {
1333 /// The root universe, where things that the user defined are
1335 pub const ROOT: UniverseIndex = UniverseIndex(0);
1337 /// A "subuniverse" corresponds to being inside a `forall` quantifier.
1338 /// So, for example, suppose we have this type in universe `U`:
1341 /// for<'a> fn(&'a u32)
1344 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1345 /// subuniverse of `U` -- in this new universe, we can name the
1346 /// region `'a`, but that region was not nameable from `U` because
1347 /// it was not in scope there.
1348 pub fn subuniverse(self) -> UniverseIndex {
1349 UniverseIndex(self.0.checked_add(1).unwrap())
1352 pub fn from(v: u32) -> UniverseIndex {
1356 pub fn as_u32(&self) -> u32 {
1360 pub fn as_usize(&self) -> usize {
1364 /// Gets the "depth" of this universe in the universe tree. This
1365 /// is not really useful except for e.g. the `HashStable`
1367 pub fn depth(&self) -> u32 {
1372 /// When type checking, we use the `ParamEnv` to track
1373 /// details about the set of where-clauses that are in scope at this
1374 /// particular point.
1375 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1376 pub struct ParamEnv<'tcx> {
1377 /// Obligations that the caller must satisfy. This is basically
1378 /// the set of bounds on the in-scope type parameters, translated
1379 /// into Obligations, and elaborated and normalized.
1380 pub caller_bounds: &'tcx Slice<ty::Predicate<'tcx>>,
1382 /// Typically, this is `Reveal::UserFacing`, but during trans we
1383 /// want `Reveal::All` -- note that this is always paired with an
1384 /// empty environment. To get that, use `ParamEnv::reveal()`.
1385 pub reveal: traits::Reveal,
1387 /// What is the innermost universe we have created? Starts out as
1388 /// `UniverseIndex::root()` but grows from there as we enter
1389 /// universal quantifiers.
1391 /// NB: At present, we exclude the universal quantifiers on the
1392 /// item we are type-checking, and just consider those names as
1393 /// part of the root universe. So this would only get incremented
1394 /// when we enter into a higher-ranked (`for<..>`) type or trait
1396 pub universe: UniverseIndex,
1399 impl<'tcx> ParamEnv<'tcx> {
1400 /// Creates a suitable environment in which to perform trait
1401 /// queries on the given value. This will either be `self` *or*
1402 /// the empty environment, depending on whether `value` references
1403 /// type parameters that are in scope. (If it doesn't, then any
1404 /// judgements should be completely independent of the context,
1405 /// and hence we can safely use the empty environment so as to
1406 /// enable more sharing across functions.)
1408 /// NB: This is a mildly dubious thing to do, in that a function
1409 /// (or other environment) might have wacky where-clauses like
1410 /// `where Box<u32>: Copy`, which are clearly never
1411 /// satisfiable. The code will at present ignore these,
1412 /// effectively, when type-checking the body of said
1413 /// function. This preserves existing behavior in any
1414 /// case. --nmatsakis
1415 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1416 assert!(!value.needs_infer());
1417 if value.has_param_types() || value.has_self_ty() {
1424 param_env: ParamEnv::empty(self.reveal),
1431 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1432 pub struct ParamEnvAnd<'tcx, T> {
1433 pub param_env: ParamEnv<'tcx>,
1437 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1438 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1439 (self.param_env, self.value)
1443 impl<'gcx, T> HashStable<StableHashingContext<'gcx>> for ParamEnvAnd<'gcx, T>
1444 where T: HashStable<StableHashingContext<'gcx>>
1446 fn hash_stable<W: StableHasherResult>(&self,
1447 hcx: &mut StableHashingContext<'gcx>,
1448 hasher: &mut StableHasher<W>) {
1454 param_env.hash_stable(hcx, hasher);
1455 value.hash_stable(hcx, hasher);
1459 #[derive(Copy, Clone, Debug)]
1460 pub struct Destructor {
1461 /// The def-id of the destructor method
1466 pub struct AdtFlags: u32 {
1467 const NO_ADT_FLAGS = 0;
1468 const IS_ENUM = 1 << 0;
1469 const IS_PHANTOM_DATA = 1 << 1;
1470 const IS_FUNDAMENTAL = 1 << 2;
1471 const IS_UNION = 1 << 3;
1472 const IS_BOX = 1 << 4;
1473 /// Indicates whether this abstract data type will be expanded on in future (new
1474 /// fields/variants) and as such, whether downstream crates must match exhaustively on the
1475 /// fields/variants of this data type.
1477 /// See RFC 2008 (<https://github.com/rust-lang/rfcs/pull/2008>).
1478 const IS_NON_EXHAUSTIVE = 1 << 5;
1483 pub struct VariantDef {
1484 /// The variant's DefId. If this is a tuple-like struct,
1485 /// this is the DefId of the struct's ctor.
1487 pub name: Name, // struct's name if this is a struct
1488 pub discr: VariantDiscr,
1489 pub fields: Vec<FieldDef>,
1490 pub ctor_kind: CtorKind,
1493 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
1494 pub enum VariantDiscr {
1495 /// Explicit value for this variant, i.e. `X = 123`.
1496 /// The `DefId` corresponds to the embedded constant.
1499 /// The previous variant's discriminant plus one.
1500 /// For efficiency reasons, the distance from the
1501 /// last `Explicit` discriminant is being stored,
1502 /// or `0` for the first variant, if it has none.
1507 pub struct FieldDef {
1510 pub vis: Visibility,
1513 /// The definition of an abstract data type - a struct or enum.
1515 /// These are all interned (by intern_adt_def) into the adt_defs
1519 pub variants: Vec<VariantDef>,
1521 pub repr: ReprOptions,
1524 impl PartialEq for AdtDef {
1525 // AdtDef are always interned and this is part of TyS equality
1527 fn eq(&self, other: &Self) -> bool { self as *const _ == other as *const _ }
1530 impl Eq for AdtDef {}
1532 impl Hash for AdtDef {
1534 fn hash<H: Hasher>(&self, s: &mut H) {
1535 (self as *const AdtDef).hash(s)
1539 impl<'tcx> serialize::UseSpecializedEncodable for &'tcx AdtDef {
1540 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1545 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx AdtDef {}
1548 impl<'gcx> HashStable<StableHashingContext<'gcx>> for AdtDef {
1549 fn hash_stable<W: StableHasherResult>(&self,
1550 hcx: &mut StableHashingContext<'gcx>,
1551 hasher: &mut StableHasher<W>) {
1553 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> =
1554 RefCell::new(FxHashMap());
1557 let hash: Fingerprint = CACHE.with(|cache| {
1558 let addr = self as *const AdtDef as usize;
1559 *cache.borrow_mut().entry(addr).or_insert_with(|| {
1567 let mut hasher = StableHasher::new();
1568 did.hash_stable(hcx, &mut hasher);
1569 variants.hash_stable(hcx, &mut hasher);
1570 flags.hash_stable(hcx, &mut hasher);
1571 repr.hash_stable(hcx, &mut hasher);
1577 hash.hash_stable(hcx, hasher);
1581 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
1582 pub enum AdtKind { Struct, Union, Enum }
1585 #[derive(RustcEncodable, RustcDecodable, Default)]
1586 pub struct ReprFlags: u8 {
1587 const IS_C = 1 << 0;
1588 const IS_PACKED = 1 << 1;
1589 const IS_SIMD = 1 << 2;
1590 const IS_TRANSPARENT = 1 << 3;
1591 // Internal only for now. If true, don't reorder fields.
1592 const IS_LINEAR = 1 << 4;
1594 // Any of these flags being set prevent field reordering optimisation.
1595 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
1596 ReprFlags::IS_PACKED.bits |
1597 ReprFlags::IS_SIMD.bits |
1598 ReprFlags::IS_LINEAR.bits;
1602 impl_stable_hash_for!(struct ReprFlags {
1608 /// Represents the repr options provided by the user,
1609 #[derive(Copy, Clone, Eq, PartialEq, RustcEncodable, RustcDecodable, Default)]
1610 pub struct ReprOptions {
1611 pub int: Option<attr::IntType>,
1613 pub flags: ReprFlags,
1616 impl_stable_hash_for!(struct ReprOptions {
1623 pub fn new(tcx: TyCtxt, did: DefId) -> ReprOptions {
1624 let mut flags = ReprFlags::empty();
1625 let mut size = None;
1626 let mut max_align = 0;
1627 for attr in tcx.get_attrs(did).iter() {
1628 for r in attr::find_repr_attrs(tcx.sess.diagnostic(), attr) {
1629 flags.insert(match r {
1630 attr::ReprC => ReprFlags::IS_C,
1631 attr::ReprPacked => ReprFlags::IS_PACKED,
1632 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1633 attr::ReprSimd => ReprFlags::IS_SIMD,
1634 attr::ReprInt(i) => {
1638 attr::ReprAlign(align) => {
1639 max_align = cmp::max(align, max_align);
1646 // This is here instead of layout because the choice must make it into metadata.
1647 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.item_path_str(did))) {
1648 flags.insert(ReprFlags::IS_LINEAR);
1650 ReprOptions { int: size, align: max_align, flags: flags }
1654 pub fn simd(&self) -> bool { self.flags.contains(ReprFlags::IS_SIMD) }
1656 pub fn c(&self) -> bool { self.flags.contains(ReprFlags::IS_C) }
1658 pub fn packed(&self) -> bool { self.flags.contains(ReprFlags::IS_PACKED) }
1660 pub fn transparent(&self) -> bool { self.flags.contains(ReprFlags::IS_TRANSPARENT) }
1662 pub fn linear(&self) -> bool { self.flags.contains(ReprFlags::IS_LINEAR) }
1664 pub fn discr_type(&self) -> attr::IntType {
1665 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1668 /// Returns true if this `#[repr()]` should inhabit "smart enum
1669 /// layout" optimizations, such as representing `Foo<&T>` as a
1671 pub fn inhibit_enum_layout_opt(&self) -> bool {
1672 self.c() || self.int.is_some()
1676 impl<'a, 'gcx, 'tcx> AdtDef {
1680 variants: Vec<VariantDef>,
1681 repr: ReprOptions) -> Self {
1682 let mut flags = AdtFlags::NO_ADT_FLAGS;
1683 let attrs = tcx.get_attrs(did);
1684 if attr::contains_name(&attrs, "fundamental") {
1685 flags = flags | AdtFlags::IS_FUNDAMENTAL;
1687 if Some(did) == tcx.lang_items().phantom_data() {
1688 flags = flags | AdtFlags::IS_PHANTOM_DATA;
1690 if Some(did) == tcx.lang_items().owned_box() {
1691 flags = flags | AdtFlags::IS_BOX;
1693 if tcx.has_attr(did, "non_exhaustive") {
1694 flags = flags | AdtFlags::IS_NON_EXHAUSTIVE;
1697 AdtKind::Enum => flags = flags | AdtFlags::IS_ENUM,
1698 AdtKind::Union => flags = flags | AdtFlags::IS_UNION,
1699 AdtKind::Struct => {}
1710 pub fn is_struct(&self) -> bool {
1711 !self.is_union() && !self.is_enum()
1715 pub fn is_union(&self) -> bool {
1716 self.flags.intersects(AdtFlags::IS_UNION)
1720 pub fn is_enum(&self) -> bool {
1721 self.flags.intersects(AdtFlags::IS_ENUM)
1725 pub fn is_non_exhaustive(&self) -> bool {
1726 self.flags.intersects(AdtFlags::IS_NON_EXHAUSTIVE)
1729 /// Returns the kind of the ADT - Struct or Enum.
1731 pub fn adt_kind(&self) -> AdtKind {
1734 } else if self.is_union() {
1741 pub fn descr(&self) -> &'static str {
1742 match self.adt_kind() {
1743 AdtKind::Struct => "struct",
1744 AdtKind::Union => "union",
1745 AdtKind::Enum => "enum",
1749 pub fn variant_descr(&self) -> &'static str {
1750 match self.adt_kind() {
1751 AdtKind::Struct => "struct",
1752 AdtKind::Union => "union",
1753 AdtKind::Enum => "variant",
1757 /// Returns whether this type is #[fundamental] for the purposes
1758 /// of coherence checking.
1760 pub fn is_fundamental(&self) -> bool {
1761 self.flags.intersects(AdtFlags::IS_FUNDAMENTAL)
1764 /// Returns true if this is PhantomData<T>.
1766 pub fn is_phantom_data(&self) -> bool {
1767 self.flags.intersects(AdtFlags::IS_PHANTOM_DATA)
1770 /// Returns true if this is Box<T>.
1772 pub fn is_box(&self) -> bool {
1773 self.flags.intersects(AdtFlags::IS_BOX)
1776 /// Returns whether this type has a destructor.
1777 pub fn has_dtor(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool {
1778 self.destructor(tcx).is_some()
1781 /// Asserts this is a struct or union and returns its unique variant.
1782 pub fn non_enum_variant(&self) -> &VariantDef {
1783 assert!(self.is_struct() || self.is_union());
1788 pub fn predicates(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> GenericPredicates<'gcx> {
1789 tcx.predicates_of(self.did)
1792 /// Returns an iterator over all fields contained
1795 pub fn all_fields<'s>(&'s self) -> impl Iterator<Item = &'s FieldDef> {
1796 self.variants.iter().flat_map(|v| v.fields.iter())
1799 pub fn is_payloadfree(&self) -> bool {
1800 !self.variants.is_empty() &&
1801 self.variants.iter().all(|v| v.fields.is_empty())
1804 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
1807 .find(|v| v.did == vid)
1808 .expect("variant_with_id: unknown variant")
1811 pub fn variant_index_with_id(&self, vid: DefId) -> usize {
1814 .position(|v| v.did == vid)
1815 .expect("variant_index_with_id: unknown variant")
1818 pub fn variant_of_def(&self, def: Def) -> &VariantDef {
1820 Def::Variant(vid) | Def::VariantCtor(vid, ..) => self.variant_with_id(vid),
1821 Def::Struct(..) | Def::StructCtor(..) | Def::Union(..) |
1822 Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => self.non_enum_variant(),
1823 _ => bug!("unexpected def {:?} in variant_of_def", def)
1828 pub fn discriminants(&'a self, tcx: TyCtxt<'a, 'gcx, 'tcx>)
1829 -> impl Iterator<Item=ConstInt> + 'a {
1830 let param_env = ParamEnv::empty(traits::Reveal::UserFacing);
1831 let repr_type = self.repr.discr_type();
1832 let initial = repr_type.initial_discriminant(tcx.global_tcx());
1833 let mut prev_discr = None::<ConstInt>;
1834 self.variants.iter().map(move |v| {
1835 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr());
1836 if let VariantDiscr::Explicit(expr_did) = v.discr {
1837 let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did);
1838 match tcx.const_eval(param_env.and((expr_did, substs))) {
1840 val: ConstVal::Value(Value::ByVal(PrimVal::Bytes(b))),
1843 trace!("discriminants: {} ({:?})", b, repr_type);
1844 use syntax::attr::IntType;
1845 discr = match repr_type {
1846 IntType::SignedInt(int_type) => ConstInt::new_signed(
1847 b as i128, int_type, tcx.sess.target.isize_ty).unwrap(),
1848 IntType::UnsignedInt(uint_type) => ConstInt::new_unsigned(
1849 b, uint_type, tcx.sess.target.usize_ty).unwrap(),
1853 if !expr_did.is_local() {
1854 span_bug!(tcx.def_span(expr_did),
1855 "variant discriminant evaluation succeeded \
1856 in its crate but failed locally: {:?}", err);
1861 prev_discr = Some(discr);
1867 /// Compute the discriminant value used by a specific variant.
1868 /// Unlike `discriminants`, this is (amortized) constant-time,
1869 /// only doing at most one query for evaluating an explicit
1870 /// discriminant (the last one before the requested variant),
1871 /// assuming there are no constant-evaluation errors there.
1872 pub fn discriminant_for_variant(&self,
1873 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1874 variant_index: usize)
1876 let param_env = ParamEnv::empty(traits::Reveal::UserFacing);
1877 let repr_type = self.repr.discr_type();
1878 let mut explicit_value = repr_type.initial_discriminant(tcx.global_tcx());
1879 let mut explicit_index = variant_index;
1881 match self.variants[explicit_index].discr {
1882 ty::VariantDiscr::Relative(0) => break,
1883 ty::VariantDiscr::Relative(distance) => {
1884 explicit_index -= distance;
1886 ty::VariantDiscr::Explicit(expr_did) => {
1887 let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did);
1888 match tcx.const_eval(param_env.and((expr_did, substs))) {
1890 val: ConstVal::Value(Value::ByVal(PrimVal::Bytes(b))),
1893 trace!("discriminants: {} ({:?})", b, repr_type);
1894 use syntax::attr::IntType;
1895 explicit_value = match repr_type {
1896 IntType::SignedInt(int_type) => ConstInt::new_signed(
1897 b as i128, int_type, tcx.sess.target.isize_ty).unwrap(),
1898 IntType::UnsignedInt(uint_type) => ConstInt::new_unsigned(
1899 b, uint_type, tcx.sess.target.usize_ty).unwrap(),
1904 if !expr_did.is_local() {
1905 span_bug!(tcx.def_span(expr_did),
1906 "variant discriminant evaluation succeeded \
1907 in its crate but failed locally: {:?}", err);
1909 if explicit_index == 0 {
1912 explicit_index -= 1;
1918 let discr = explicit_value.to_u128_unchecked()
1919 .wrapping_add((variant_index - explicit_index) as u128);
1921 attr::UnsignedInt(ty) => {
1922 ConstInt::new_unsigned_truncating(discr, ty,
1923 tcx.sess.target.usize_ty)
1925 attr::SignedInt(ty) => {
1926 ConstInt::new_signed_truncating(discr as i128, ty,
1927 tcx.sess.target.isize_ty)
1932 pub fn destructor(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Destructor> {
1933 tcx.adt_destructor(self.did)
1936 /// Returns a list of types such that `Self: Sized` if and only
1937 /// if that type is Sized, or `TyErr` if this type is recursive.
1939 /// Oddly enough, checking that the sized-constraint is Sized is
1940 /// actually more expressive than checking all members:
1941 /// the Sized trait is inductive, so an associated type that references
1942 /// Self would prevent its containing ADT from being Sized.
1944 /// Due to normalization being eager, this applies even if
1945 /// the associated type is behind a pointer, e.g. issue #31299.
1946 pub fn sized_constraint(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> &'tcx [Ty<'tcx>] {
1947 match queries::adt_sized_constraint::try_get(tcx, DUMMY_SP, self.did) {
1950 debug!("adt_sized_constraint: {:?} is recursive", self);
1951 // This should be reported as an error by `check_representable`.
1953 // Consider the type as Sized in the meanwhile to avoid
1954 // further errors. Delay our `bug` diagnostic here to get
1955 // emitted later as well in case we accidentally otherwise don't
1958 tcx.intern_type_list(&[tcx.types.err])
1963 fn sized_constraint_for_ty(&self,
1964 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1967 let result = match ty.sty {
1968 TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) |
1969 TyRawPtr(..) | TyRef(..) | TyFnDef(..) | TyFnPtr(_) |
1970 TyArray(..) | TyClosure(..) | TyGenerator(..) | TyNever => {
1979 TyGeneratorWitness(..) => {
1980 // these are never sized - return the target type
1984 TyTuple(ref tys, _) => {
1987 Some(ty) => self.sized_constraint_for_ty(tcx, ty)
1991 TyAdt(adt, substs) => {
1993 let adt_tys = adt.sized_constraint(tcx);
1994 debug!("sized_constraint_for_ty({:?}) intermediate = {:?}",
1997 .map(|ty| ty.subst(tcx, substs))
1998 .flat_map(|ty| self.sized_constraint_for_ty(tcx, ty))
2002 TyProjection(..) | TyAnon(..) => {
2003 // must calculate explicitly.
2004 // FIXME: consider special-casing always-Sized projections
2009 // perf hack: if there is a `T: Sized` bound, then
2010 // we know that `T` is Sized and do not need to check
2013 let sized_trait = match tcx.lang_items().sized_trait() {
2015 _ => return vec![ty]
2017 let sized_predicate = Binder(TraitRef {
2018 def_id: sized_trait,
2019 substs: tcx.mk_substs_trait(ty, &[])
2021 let predicates = tcx.predicates_of(self.did).predicates;
2022 if predicates.into_iter().any(|p| p == sized_predicate) {
2030 bug!("unexpected type `{:?}` in sized_constraint_for_ty",
2034 debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result);
2039 impl<'a, 'gcx, 'tcx> VariantDef {
2041 pub fn find_field_named(&self, name: ast::Name) -> Option<&FieldDef> {
2042 self.index_of_field_named(name).map(|index| &self.fields[index])
2045 pub fn index_of_field_named(&self, name: ast::Name) -> Option<usize> {
2046 if let Some(index) = self.fields.iter().position(|f| f.name == name) {
2049 let mut ident = name.to_ident();
2050 while ident.ctxt != SyntaxContext::empty() {
2051 ident.ctxt.remove_mark();
2052 if let Some(field) = self.fields.iter().position(|f| f.name.to_ident() == ident) {
2060 pub fn field_named(&self, name: ast::Name) -> &FieldDef {
2061 self.find_field_named(name).unwrap()
2065 impl<'a, 'gcx, 'tcx> FieldDef {
2066 pub fn ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, subst: &Substs<'tcx>) -> Ty<'tcx> {
2067 tcx.type_of(self.did).subst(tcx, subst)
2071 /// Represents the various closure traits in the Rust language. This
2072 /// will determine the type of the environment (`self`, in the
2073 /// desuaring) argument that the closure expects.
2075 /// You can get the environment type of a closure using
2076 /// `tcx.closure_env_ty()`.
2077 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
2078 pub enum ClosureKind {
2079 // Warning: Ordering is significant here! The ordering is chosen
2080 // because the trait Fn is a subtrait of FnMut and so in turn, and
2081 // hence we order it so that Fn < FnMut < FnOnce.
2087 impl<'a, 'tcx> ClosureKind {
2088 // This is the initial value used when doing upvar inference.
2089 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2091 pub fn trait_did(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> DefId {
2093 ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem),
2094 ClosureKind::FnMut => {
2095 tcx.require_lang_item(FnMutTraitLangItem)
2097 ClosureKind::FnOnce => {
2098 tcx.require_lang_item(FnOnceTraitLangItem)
2103 /// True if this a type that impls this closure kind
2104 /// must also implement `other`.
2105 pub fn extends(self, other: ty::ClosureKind) -> bool {
2106 match (self, other) {
2107 (ClosureKind::Fn, ClosureKind::Fn) => true,
2108 (ClosureKind::Fn, ClosureKind::FnMut) => true,
2109 (ClosureKind::Fn, ClosureKind::FnOnce) => true,
2110 (ClosureKind::FnMut, ClosureKind::FnMut) => true,
2111 (ClosureKind::FnMut, ClosureKind::FnOnce) => true,
2112 (ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
2117 /// Returns the representative scalar type for this closure kind.
2118 /// See `TyS::to_opt_closure_kind` for more details.
2119 pub fn to_ty(self, tcx: TyCtxt<'_, '_, 'tcx>) -> Ty<'tcx> {
2121 ty::ClosureKind::Fn => tcx.types.i8,
2122 ty::ClosureKind::FnMut => tcx.types.i16,
2123 ty::ClosureKind::FnOnce => tcx.types.i32,
2128 impl<'tcx> TyS<'tcx> {
2129 /// Iterator that walks `self` and any types reachable from
2130 /// `self`, in depth-first order. Note that just walks the types
2131 /// that appear in `self`, it does not descend into the fields of
2132 /// structs or variants. For example:
2135 /// isize => { isize }
2136 /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
2137 /// [isize] => { [isize], isize }
2139 pub fn walk(&'tcx self) -> TypeWalker<'tcx> {
2140 TypeWalker::new(self)
2143 /// Iterator that walks the immediate children of `self`. Hence
2144 /// `Foo<Bar<i32>, u32>` yields the sequence `[Bar<i32>, u32]`
2145 /// (but not `i32`, like `walk`).
2146 pub fn walk_shallow(&'tcx self) -> AccIntoIter<walk::TypeWalkerArray<'tcx>> {
2147 walk::walk_shallow(self)
2150 /// Walks `ty` and any types appearing within `ty`, invoking the
2151 /// callback `f` on each type. If the callback returns false, then the
2152 /// children of the current type are ignored.
2154 /// Note: prefer `ty.walk()` where possible.
2155 pub fn maybe_walk<F>(&'tcx self, mut f: F)
2156 where F : FnMut(Ty<'tcx>) -> bool
2158 let mut walker = self.walk();
2159 while let Some(ty) = walker.next() {
2161 walker.skip_current_subtree();
2168 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2170 hir::MutMutable => MutBorrow,
2171 hir::MutImmutable => ImmBorrow,
2175 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2176 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2177 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2179 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2181 MutBorrow => hir::MutMutable,
2182 ImmBorrow => hir::MutImmutable,
2184 // We have no type corresponding to a unique imm borrow, so
2185 // use `&mut`. It gives all the capabilities of an `&uniq`
2186 // and hence is a safe "over approximation".
2187 UniqueImmBorrow => hir::MutMutable,
2191 pub fn to_user_str(&self) -> &'static str {
2193 MutBorrow => "mutable",
2194 ImmBorrow => "immutable",
2195 UniqueImmBorrow => "uniquely immutable",
2200 #[derive(Debug, Clone)]
2201 pub enum Attributes<'gcx> {
2202 Owned(Lrc<[ast::Attribute]>),
2203 Borrowed(&'gcx [ast::Attribute])
2206 impl<'gcx> ::std::ops::Deref for Attributes<'gcx> {
2207 type Target = [ast::Attribute];
2209 fn deref(&self) -> &[ast::Attribute] {
2211 &Attributes::Owned(ref data) => &data,
2212 &Attributes::Borrowed(data) => data
2217 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
2218 pub fn body_tables(self, body: hir::BodyId) -> &'gcx TypeckTables<'gcx> {
2219 self.typeck_tables_of(self.hir.body_owner_def_id(body))
2222 /// Returns an iterator of the def-ids for all body-owners in this
2223 /// crate. If you would prefer to iterate over the bodies
2224 /// themselves, you can do `self.hir.krate().body_ids.iter()`.
2225 pub fn body_owners(self) -> impl Iterator<Item = DefId> + 'a {
2229 .map(move |&body_id| self.hir.body_owner_def_id(body_id))
2232 pub fn expr_span(self, id: NodeId) -> Span {
2233 match self.hir.find(id) {
2234 Some(hir_map::NodeExpr(e)) => {
2238 bug!("Node id {} is not an expr: {:?}", id, f);
2241 bug!("Node id {} is not present in the node map", id);
2246 pub fn provided_trait_methods(self, id: DefId) -> Vec<AssociatedItem> {
2247 self.associated_items(id)
2248 .filter(|item| item.kind == AssociatedKind::Method && item.defaultness.has_value())
2252 pub fn trait_relevant_for_never(self, did: DefId) -> bool {
2253 self.associated_items(did).any(|item| {
2254 item.relevant_for_never()
2258 pub fn opt_associated_item(self, def_id: DefId) -> Option<AssociatedItem> {
2259 let is_associated_item = if let Some(node_id) = self.hir.as_local_node_id(def_id) {
2260 match self.hir.get(node_id) {
2261 hir_map::NodeTraitItem(_) | hir_map::NodeImplItem(_) => true,
2265 match self.describe_def(def_id).expect("no def for def-id") {
2266 Def::AssociatedConst(_) | Def::Method(_) | Def::AssociatedTy(_) => true,
2271 if is_associated_item {
2272 Some(self.associated_item(def_id))
2278 fn associated_item_from_trait_item_ref(self,
2279 parent_def_id: DefId,
2280 parent_vis: &hir::Visibility,
2281 trait_item_ref: &hir::TraitItemRef)
2283 let def_id = self.hir.local_def_id(trait_item_ref.id.node_id);
2284 let (kind, has_self) = match trait_item_ref.kind {
2285 hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false),
2286 hir::AssociatedItemKind::Method { has_self } => {
2287 (ty::AssociatedKind::Method, has_self)
2289 hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false),
2293 name: trait_item_ref.name,
2295 // Visibility of trait items is inherited from their traits.
2296 vis: Visibility::from_hir(parent_vis, trait_item_ref.id.node_id, self),
2297 defaultness: trait_item_ref.defaultness,
2299 container: TraitContainer(parent_def_id),
2300 method_has_self_argument: has_self
2304 fn associated_item_from_impl_item_ref(self,
2305 parent_def_id: DefId,
2306 impl_item_ref: &hir::ImplItemRef)
2308 let def_id = self.hir.local_def_id(impl_item_ref.id.node_id);
2309 let (kind, has_self) = match impl_item_ref.kind {
2310 hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false),
2311 hir::AssociatedItemKind::Method { has_self } => {
2312 (ty::AssociatedKind::Method, has_self)
2314 hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false),
2317 ty::AssociatedItem {
2318 name: impl_item_ref.name,
2320 // Visibility of trait impl items doesn't matter.
2321 vis: ty::Visibility::from_hir(&impl_item_ref.vis, impl_item_ref.id.node_id, self),
2322 defaultness: impl_item_ref.defaultness,
2324 container: ImplContainer(parent_def_id),
2325 method_has_self_argument: has_self
2329 #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
2330 pub fn associated_items(self, def_id: DefId)
2331 -> impl Iterator<Item = ty::AssociatedItem> + 'a {
2332 let def_ids = self.associated_item_def_ids(def_id);
2333 (0..def_ids.len()).map(move |i| self.associated_item(def_ids[i]))
2336 /// Returns true if the impls are the same polarity and are implementing
2337 /// a trait which contains no items
2338 pub fn impls_are_allowed_to_overlap(self, def_id1: DefId, def_id2: DefId) -> bool {
2339 if !self.features().overlapping_marker_traits {
2342 let trait1_is_empty = self.impl_trait_ref(def_id1)
2343 .map_or(false, |trait_ref| {
2344 self.associated_item_def_ids(trait_ref.def_id).is_empty()
2346 let trait2_is_empty = self.impl_trait_ref(def_id2)
2347 .map_or(false, |trait_ref| {
2348 self.associated_item_def_ids(trait_ref.def_id).is_empty()
2350 self.impl_polarity(def_id1) == self.impl_polarity(def_id2)
2355 // Returns `ty::VariantDef` if `def` refers to a struct,
2356 // or variant or their constructors, panics otherwise.
2357 pub fn expect_variant_def(self, def: Def) -> &'tcx VariantDef {
2359 Def::Variant(did) | Def::VariantCtor(did, ..) => {
2360 let enum_did = self.parent_def_id(did).unwrap();
2361 self.adt_def(enum_did).variant_with_id(did)
2363 Def::Struct(did) | Def::Union(did) => {
2364 self.adt_def(did).non_enum_variant()
2366 Def::StructCtor(ctor_did, ..) => {
2367 let did = self.parent_def_id(ctor_did).expect("struct ctor has no parent");
2368 self.adt_def(did).non_enum_variant()
2370 _ => bug!("expect_variant_def used with unexpected def {:?}", def)
2374 /// Given a `VariantDef`, returns the def-id of the `AdtDef` of which it is a part.
2375 pub fn adt_def_id_of_variant(self, variant_def: &'tcx VariantDef) -> DefId {
2376 let def_key = self.def_key(variant_def.did);
2377 match def_key.disambiguated_data.data {
2378 // for enum variants and tuple structs, the def-id of the ADT itself
2379 // is the *parent* of the variant
2380 DefPathData::EnumVariant(..) | DefPathData::StructCtor =>
2381 DefId { krate: variant_def.did.krate, index: def_key.parent.unwrap() },
2383 // otherwise, for structs and unions, they share a def-id
2384 _ => variant_def.did,
2388 pub fn item_name(self, id: DefId) -> InternedString {
2389 if id.index == CRATE_DEF_INDEX {
2390 self.original_crate_name(id.krate).as_str()
2392 let def_key = self.def_key(id);
2393 // The name of a StructCtor is that of its struct parent.
2394 if let hir_map::DefPathData::StructCtor = def_key.disambiguated_data.data {
2395 self.item_name(DefId {
2397 index: def_key.parent.unwrap()
2400 def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
2401 bug!("item_name: no name for {:?}", self.def_path(id));
2407 /// Return the possibly-auto-generated MIR of a (DefId, Subst) pair.
2408 pub fn instance_mir(self, instance: ty::InstanceDef<'gcx>)
2412 ty::InstanceDef::Item(did) => {
2413 self.optimized_mir(did)
2415 ty::InstanceDef::Intrinsic(..) |
2416 ty::InstanceDef::FnPtrShim(..) |
2417 ty::InstanceDef::Virtual(..) |
2418 ty::InstanceDef::ClosureOnceShim { .. } |
2419 ty::InstanceDef::DropGlue(..) |
2420 ty::InstanceDef::CloneShim(..) => {
2421 self.mir_shims(instance)
2426 /// Given the DefId of an item, returns its MIR, borrowed immutably.
2427 /// Returns None if there is no MIR for the DefId
2428 pub fn maybe_optimized_mir(self, did: DefId) -> Option<&'gcx Mir<'gcx>> {
2429 if self.is_mir_available(did) {
2430 Some(self.optimized_mir(did))
2436 /// Get the attributes of a definition.
2437 pub fn get_attrs(self, did: DefId) -> Attributes<'gcx> {
2438 if let Some(id) = self.hir.as_local_node_id(did) {
2439 Attributes::Borrowed(self.hir.attrs(id))
2441 Attributes::Owned(self.item_attrs(did))
2445 /// Determine whether an item is annotated with an attribute
2446 pub fn has_attr(self, did: DefId, attr: &str) -> bool {
2447 attr::contains_name(&self.get_attrs(did), attr)
2450 /// Returns true if this is an `auto trait`.
2451 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2452 self.trait_def(trait_def_id).has_auto_impl
2455 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
2456 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
2459 /// Given the def_id of an impl, return the def_id of the trait it implements.
2460 /// If it implements no trait, return `None`.
2461 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2462 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2465 /// If the given def ID describes a method belonging to an impl, return the
2466 /// ID of the impl that the method belongs to. Otherwise, return `None`.
2467 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2468 let item = if def_id.krate != LOCAL_CRATE {
2469 if let Some(Def::Method(_)) = self.describe_def(def_id) {
2470 Some(self.associated_item(def_id))
2475 self.opt_associated_item(def_id)
2479 Some(trait_item) => {
2480 match trait_item.container {
2481 TraitContainer(_) => None,
2482 ImplContainer(def_id) => Some(def_id),
2489 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2490 /// with the name of the crate containing the impl.
2491 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2492 if impl_did.is_local() {
2493 let node_id = self.hir.as_local_node_id(impl_did).unwrap();
2494 Ok(self.hir.span(node_id))
2496 Err(self.crate_name(impl_did.krate))
2500 // Hygienically compare a use-site name (`use_name`) for a field or an associated item with its
2501 // supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2502 // definition's parent/scope to perform comparison.
2503 pub fn hygienic_eq(self, use_name: Name, def_name: Name, def_parent_def_id: DefId) -> bool {
2504 self.adjust(use_name, def_parent_def_id, DUMMY_NODE_ID).0 == def_name.to_ident()
2507 pub fn adjust(self, name: Name, scope: DefId, block: NodeId) -> (Ident, DefId) {
2508 self.adjust_ident(name.to_ident(), scope, block)
2511 pub fn adjust_ident(self, mut ident: Ident, scope: DefId, block: NodeId) -> (Ident, DefId) {
2512 let expansion = match scope.krate {
2513 LOCAL_CRATE => self.hir.definitions().expansion(scope.index),
2516 let scope = match ident.ctxt.adjust(expansion) {
2517 Some(macro_def) => self.hir.definitions().macro_def_scope(macro_def),
2518 None if block == DUMMY_NODE_ID => DefId::local(CRATE_DEF_INDEX), // Dummy DefId
2519 None => self.hir.get_module_parent(block),
2525 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
2526 pub fn with_freevars<T, F>(self, fid: NodeId, f: F) -> T where
2527 F: FnOnce(&[hir::Freevar]) -> T,
2529 let def_id = self.hir.local_def_id(fid);
2530 match self.freevars(def_id) {
2537 fn associated_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId)
2540 let id = tcx.hir.as_local_node_id(def_id).unwrap();
2541 let parent_id = tcx.hir.get_parent(id);
2542 let parent_def_id = tcx.hir.local_def_id(parent_id);
2543 let parent_item = tcx.hir.expect_item(parent_id);
2544 match parent_item.node {
2545 hir::ItemImpl(.., ref impl_item_refs) => {
2546 if let Some(impl_item_ref) = impl_item_refs.iter().find(|i| i.id.node_id == id) {
2547 let assoc_item = tcx.associated_item_from_impl_item_ref(parent_def_id,
2549 debug_assert_eq!(assoc_item.def_id, def_id);
2554 hir::ItemTrait(.., ref trait_item_refs) => {
2555 if let Some(trait_item_ref) = trait_item_refs.iter().find(|i| i.id.node_id == id) {
2556 let assoc_item = tcx.associated_item_from_trait_item_ref(parent_def_id,
2559 debug_assert_eq!(assoc_item.def_id, def_id);
2567 span_bug!(parent_item.span,
2568 "unexpected parent of trait or impl item or item not found: {:?}",
2572 /// Calculates the Sized-constraint.
2574 /// In fact, there are only a few options for the types in the constraint:
2575 /// - an obviously-unsized type
2576 /// - a type parameter or projection whose Sizedness can't be known
2577 /// - a tuple of type parameters or projections, if there are multiple
2579 /// - a TyError, if a type contained itself. The representability
2580 /// check should catch this case.
2581 fn adt_sized_constraint<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2583 -> &'tcx [Ty<'tcx>] {
2584 let def = tcx.adt_def(def_id);
2586 let result = tcx.intern_type_list(&def.variants.iter().flat_map(|v| {
2589 def.sized_constraint_for_ty(tcx, tcx.type_of(f.did))
2590 }).collect::<Vec<_>>());
2592 debug!("adt_sized_constraint: {:?} => {:?}", def, result);
2597 /// Calculates the dtorck constraint for a type.
2598 fn adt_dtorck_constraint<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2600 -> DtorckConstraint<'tcx> {
2601 let def = tcx.adt_def(def_id);
2602 let span = tcx.def_span(def_id);
2603 debug!("dtorck_constraint: {:?}", def);
2605 if def.is_phantom_data() {
2606 let result = DtorckConstraint {
2609 tcx.mk_param_from_def(&tcx.generics_of(def_id).types[0])
2612 debug!("dtorck_constraint: {:?} => {:?}", def, result);
2616 let mut result = def.all_fields()
2617 .map(|field| tcx.type_of(field.did))
2618 .map(|fty| tcx.dtorck_constraint_for_ty(span, fty, 0, fty))
2619 .collect::<Result<DtorckConstraint, ErrorReported>>()
2620 .unwrap_or(DtorckConstraint::empty());
2621 result.outlives.extend(tcx.destructor_constraints(def));
2624 debug!("dtorck_constraint: {:?} => {:?}", def, result);
2629 fn associated_item_def_ids<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2631 -> Lrc<Vec<DefId>> {
2632 let id = tcx.hir.as_local_node_id(def_id).unwrap();
2633 let item = tcx.hir.expect_item(id);
2634 let vec: Vec<_> = match item.node {
2635 hir::ItemTrait(.., ref trait_item_refs) => {
2636 trait_item_refs.iter()
2637 .map(|trait_item_ref| trait_item_ref.id)
2638 .map(|id| tcx.hir.local_def_id(id.node_id))
2641 hir::ItemImpl(.., ref impl_item_refs) => {
2642 impl_item_refs.iter()
2643 .map(|impl_item_ref| impl_item_ref.id)
2644 .map(|id| tcx.hir.local_def_id(id.node_id))
2647 hir::ItemTraitAlias(..) => vec![],
2648 _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait")
2653 fn def_span<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Span {
2654 tcx.hir.span_if_local(def_id).unwrap()
2657 /// If the given def ID describes an item belonging to a trait,
2658 /// return the ID of the trait that the trait item belongs to.
2659 /// Otherwise, return `None`.
2660 fn trait_of_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Option<DefId> {
2661 tcx.opt_associated_item(def_id)
2662 .and_then(|associated_item| {
2663 match associated_item.container {
2664 TraitContainer(def_id) => Some(def_id),
2665 ImplContainer(_) => None
2670 /// See `ParamEnv` struct def'n for details.
2671 fn param_env<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2674 // Compute the bounds on Self and the type parameters.
2676 let bounds = tcx.predicates_of(def_id).instantiate_identity(tcx);
2677 let predicates = bounds.predicates;
2679 // Finally, we have to normalize the bounds in the environment, in
2680 // case they contain any associated type projections. This process
2681 // can yield errors if the put in illegal associated types, like
2682 // `<i32 as Foo>::Bar` where `i32` does not implement `Foo`. We
2683 // report these errors right here; this doesn't actually feel
2684 // right to me, because constructing the environment feels like a
2685 // kind of a "idempotent" action, but I'm not sure where would be
2686 // a better place. In practice, we construct environments for
2687 // every fn once during type checking, and we'll abort if there
2688 // are any errors at that point, so after type checking you can be
2689 // sure that this will succeed without errors anyway.
2691 let unnormalized_env = ty::ParamEnv::new(tcx.intern_predicates(&predicates),
2692 traits::Reveal::UserFacing,
2693 ty::UniverseIndex::ROOT);
2695 let body_id = tcx.hir.as_local_node_id(def_id).map_or(DUMMY_NODE_ID, |id| {
2696 tcx.hir.maybe_body_owned_by(id).map_or(id, |body| body.node_id)
2698 let cause = traits::ObligationCause::misc(tcx.def_span(def_id), body_id);
2699 traits::normalize_param_env_or_error(tcx, def_id, unnormalized_env, cause)
2702 fn crate_disambiguator<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2703 crate_num: CrateNum) -> CrateDisambiguator {
2704 assert_eq!(crate_num, LOCAL_CRATE);
2705 tcx.sess.local_crate_disambiguator()
2708 fn original_crate_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2709 crate_num: CrateNum) -> Symbol {
2710 assert_eq!(crate_num, LOCAL_CRATE);
2711 tcx.crate_name.clone()
2714 fn crate_hash<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2715 crate_num: CrateNum)
2717 assert_eq!(crate_num, LOCAL_CRATE);
2721 fn instance_def_size_estimate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
2722 instance_def: InstanceDef<'tcx>)
2724 match instance_def {
2725 InstanceDef::Item(..) |
2726 InstanceDef::DropGlue(..) => {
2727 let mir = tcx.instance_mir(instance_def);
2728 mir.basic_blocks().iter().map(|bb| bb.statements.len()).sum()
2730 // Estimate the size of other compiler-generated shims to be 1.
2735 pub fn provide(providers: &mut ty::maps::Providers) {
2736 context::provide(providers);
2737 erase_regions::provide(providers);
2738 layout::provide(providers);
2739 util::provide(providers);
2740 *providers = ty::maps::Providers {
2742 associated_item_def_ids,
2743 adt_sized_constraint,
2744 adt_dtorck_constraint,
2748 crate_disambiguator,
2749 original_crate_name,
2751 trait_impls_of: trait_def::trait_impls_of_provider,
2752 instance_def_size_estimate,
2757 /// A map for the local crate mapping each type to a vector of its
2758 /// inherent impls. This is not meant to be used outside of coherence;
2759 /// rather, you should request the vector for a specific type via
2760 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2761 /// (constructing this map requires touching the entire crate).
2762 #[derive(Clone, Debug)]
2763 pub struct CrateInherentImpls {
2764 pub inherent_impls: DefIdMap<Lrc<Vec<DefId>>>,
2767 /// A set of constraints that need to be satisfied in order for
2768 /// a type to be valid for destruction.
2769 #[derive(Clone, Debug)]
2770 pub struct DtorckConstraint<'tcx> {
2771 /// Types that are required to be alive in order for this
2772 /// type to be valid for destruction.
2773 pub outlives: Vec<ty::subst::Kind<'tcx>>,
2774 /// Types that could not be resolved: projections and params.
2775 pub dtorck_types: Vec<Ty<'tcx>>,
2778 impl<'tcx> FromIterator<DtorckConstraint<'tcx>> for DtorckConstraint<'tcx>
2780 fn from_iter<I: IntoIterator<Item=DtorckConstraint<'tcx>>>(iter: I) -> Self {
2781 let mut result = Self::empty();
2783 for constraint in iter {
2784 result.outlives.extend(constraint.outlives);
2785 result.dtorck_types.extend(constraint.dtorck_types);
2793 impl<'tcx> DtorckConstraint<'tcx> {
2794 fn empty() -> DtorckConstraint<'tcx> {
2797 dtorck_types: vec![]
2801 fn dedup<'a>(&mut self) {
2802 let mut outlives = FxHashSet();
2803 let mut dtorck_types = FxHashSet();
2805 self.outlives.retain(|&val| outlives.replace(val).is_none());
2806 self.dtorck_types.retain(|&val| dtorck_types.replace(val).is_none());
2810 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable)]
2811 pub struct SymbolName {
2812 // FIXME: we don't rely on interning or equality here - better have
2813 // this be a `&'tcx str`.
2814 pub name: InternedString
2817 impl_stable_hash_for!(struct self::SymbolName {
2822 pub fn new(name: &str) -> SymbolName {
2824 name: Symbol::intern(name).as_str()
2829 impl Deref for SymbolName {
2832 fn deref(&self) -> &str { &self.name }
2835 impl fmt::Display for SymbolName {
2836 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2837 fmt::Display::fmt(&self.name, fmt)
2841 impl fmt::Debug for SymbolName {
2842 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
2843 fmt::Display::fmt(&self.name, fmt)