1 // ignore-tidy-filelength
3 pub use self::Variance::*;
4 pub use self::AssocItemContainer::*;
5 pub use self::BorrowKind::*;
6 pub use self::IntVarValue::*;
7 pub use self::fold::TypeFoldable;
9 use crate::hir::{map as hir_map, GlobMap, TraitMap};
11 use crate::hir::def::{Res, DefKind, CtorOf, CtorKind, ExportMap};
12 use crate::hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
13 use rustc_data_structures::svh::Svh;
14 use rustc_macros::HashStable;
15 use crate::ich::Fingerprint;
16 use crate::ich::StableHashingContext;
17 use crate::infer::canonical::Canonical;
18 use crate::middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem};
19 use crate::middle::resolve_lifetime::ObjectLifetimeDefault;
21 use crate::mir::interpret::{GlobalId, ErrorHandled};
22 use crate::mir::GeneratorLayout;
23 use crate::session::CrateDisambiguator;
24 use crate::traits::{self, Reveal};
26 use crate::ty::layout::VariantIdx;
27 use crate::ty::subst::{Subst, InternalSubsts, SubstsRef};
28 use crate::ty::util::{IntTypeExt, Discr};
29 use crate::ty::walk::TypeWalker;
30 use crate::util::captures::Captures;
31 use crate::util::nodemap::{NodeSet, DefIdMap, FxHashMap};
32 use arena::SyncDroplessArena;
33 use crate::session::DataTypeKind;
35 use rustc_serialize::{self, Encodable, Encoder};
36 use rustc_target::abi::Align;
37 use std::cell::RefCell;
38 use std::cmp::{self, Ordering};
40 use std::hash::{Hash, Hasher};
42 use rustc_data_structures::sync::{self, Lrc, ParallelIterator, par_iter};
46 use syntax::ast::{self, Name, Ident, NodeId};
48 use syntax::ext::hygiene::ExpnId;
49 use syntax::symbol::{kw, sym, Symbol, InternedString};
53 use rustc_data_structures::fx::FxIndexMap;
54 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
55 use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
60 pub use self::sty::{Binder, BoundTy, BoundTyKind, BoundVar, DebruijnIndex, INNERMOST};
61 pub use self::sty::{FnSig, GenSig, CanonicalPolyFnSig, PolyFnSig, PolyGenSig};
62 pub use self::sty::{InferTy, ParamTy, ParamConst, InferConst, ProjectionTy, ExistentialPredicate};
63 pub use self::sty::{ClosureSubsts, GeneratorSubsts, UpvarSubsts, TypeAndMut};
64 pub use self::sty::{TraitRef, TyKind, PolyTraitRef};
65 pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
66 pub use self::sty::{ExistentialProjection, PolyExistentialProjection, Const};
67 pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
68 pub use self::sty::RegionKind;
69 pub use self::sty::{TyVid, IntVid, FloatVid, ConstVid, RegionVid};
70 pub use self::sty::BoundRegion::*;
71 pub use self::sty::InferTy::*;
72 pub use self::sty::RegionKind::*;
73 pub use self::sty::TyKind::*;
75 pub use self::binding::BindingMode;
76 pub use self::binding::BindingMode::*;
78 pub use self::context::{TyCtxt, FreeRegionInfo, AllArenas, tls, keep_local};
79 pub use self::context::{Lift, TypeckTables, CtxtInterners, GlobalCtxt};
80 pub use self::context::{
81 UserTypeAnnotationIndex, UserType, CanonicalUserType,
82 CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, ResolvedOpaqueTy,
85 pub use self::instance::{Instance, InstanceDef};
87 pub use self::trait_def::TraitDef;
89 pub use self::query::queries;
102 pub mod inhabitedness;
118 mod structural_impls;
124 pub struct Resolutions {
125 pub trait_map: TraitMap,
126 pub maybe_unused_trait_imports: NodeSet,
127 pub maybe_unused_extern_crates: Vec<(NodeId, Span)>,
128 pub export_map: ExportMap<NodeId>,
129 pub glob_map: GlobMap,
130 /// Extern prelude entries. The value is `true` if the entry was introduced
131 /// via `extern crate` item and not `--extern` option or compiler built-in.
132 pub extern_prelude: FxHashMap<Name, bool>,
135 #[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable)]
136 pub enum AssocItemContainer {
137 TraitContainer(DefId),
138 ImplContainer(DefId),
141 impl AssocItemContainer {
142 /// Asserts that this is the `DefId` of an associated item declared
143 /// in a trait, and returns the trait `DefId`.
144 pub fn assert_trait(&self) -> DefId {
146 TraitContainer(id) => id,
147 _ => bug!("associated item has wrong container type: {:?}", self)
151 pub fn id(&self) -> DefId {
153 TraitContainer(id) => id,
154 ImplContainer(id) => id,
159 /// The "header" of an impl is everything outside the body: a Self type, a trait
160 /// ref (in the case of a trait impl), and a set of predicates (from the
161 /// bounds / where-clauses).
162 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
163 pub struct ImplHeader<'tcx> {
164 pub impl_def_id: DefId,
165 pub self_ty: Ty<'tcx>,
166 pub trait_ref: Option<TraitRef<'tcx>>,
167 pub predicates: Vec<Predicate<'tcx>>,
170 #[derive(Copy, Clone, Debug, PartialEq, HashStable)]
171 pub struct AssocItem {
173 #[stable_hasher(project(name))]
177 pub defaultness: hir::Defaultness,
178 pub container: AssocItemContainer,
180 /// Whether this is a method with an explicit self
181 /// as its first argument, allowing method calls.
182 pub method_has_self_argument: bool,
185 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash, RustcEncodable, RustcDecodable, HashStable)]
194 pub fn def_kind(&self) -> DefKind {
196 AssocKind::Const => DefKind::AssocConst,
197 AssocKind::Method => DefKind::Method,
198 AssocKind::Type => DefKind::AssocTy,
199 AssocKind::OpaqueTy => DefKind::AssocOpaqueTy,
203 /// Tests whether the associated item admits a non-trivial implementation
205 pub fn relevant_for_never(&self) -> bool {
207 AssocKind::OpaqueTy |
209 AssocKind::Type => true,
210 // FIXME(canndrew): Be more thorough here, check if any argument is uninhabited.
211 AssocKind::Method => !self.method_has_self_argument,
215 pub fn signature(&self, tcx: TyCtxt<'_>) -> String {
217 ty::AssocKind::Method => {
218 // We skip the binder here because the binder would deanonymize all
219 // late-bound regions, and we don't want method signatures to show up
220 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
221 // regions just fine, showing `fn(&MyType)`.
222 tcx.fn_sig(self.def_id).skip_binder().to_string()
224 ty::AssocKind::Type => format!("type {};", self.ident),
225 // FIXME(type_alias_impl_trait): we should print bounds here too.
226 ty::AssocKind::OpaqueTy => format!("type {};", self.ident),
227 ty::AssocKind::Const => {
228 format!("const {}: {:?};", self.ident, tcx.type_of(self.def_id))
234 #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable, HashStable)]
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<'tcx> DefIdTree for TyCtxt<'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: hir::HirId, tcx: TyCtxt<'_>) -> Self {
270 match visibility.node {
271 hir::VisibilityKind::Public => Visibility::Public,
272 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
273 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
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 Res::Err => Visibility::Public,
277 def => Visibility::Restricted(def.def_id()),
279 hir::VisibilityKind::Inherited => {
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(Copy, Clone, PartialEq, Eq, RustcDecodable, RustcEncodable, Hash, HashStable)]
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 #[derive(HashStable)]
336 pub struct CrateVariancesMap<'tcx> {
337 /// For each item with generics, maps to a vector of the variance
338 /// of its generics. If an item has no generics, it will have no
340 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
344 /// `a.xform(b)` combines the variance of a context with the
345 /// variance of a type with the following meaning. If we are in a
346 /// context with variance `a`, and we encounter a type argument in
347 /// a position with variance `b`, then `a.xform(b)` is the new
348 /// variance with which the argument appears.
354 /// Here, the "ambient" variance starts as covariant. `*mut T` is
355 /// invariant with respect to `T`, so the variance in which the
356 /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which
357 /// yields `Invariant`. Now, the type `Vec<T>` is covariant with
358 /// respect to its type argument `T`, and hence the variance of
359 /// the `i32` here is `Invariant.xform(Covariant)`, which results
360 /// (again) in `Invariant`.
364 /// fn(*const Vec<i32>, *mut Vec<i32)
366 /// The ambient variance is covariant. A `fn` type is
367 /// contravariant with respect to its parameters, so the variance
368 /// within which both pointer types appear is
369 /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const
370 /// T` is covariant with respect to `T`, so the variance within
371 /// which the first `Vec<i32>` appears is
372 /// `Contravariant.xform(Covariant)` or `Contravariant`. The same
373 /// is true for its `i32` argument. In the `*mut T` case, the
374 /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`,
375 /// and hence the outermost type is `Invariant` with respect to
376 /// `Vec<i32>` (and its `i32` argument).
378 /// Source: Figure 1 of "Taming the Wildcards:
379 /// Combining Definition- and Use-Site Variance" published in PLDI'11.
380 pub fn xform(self, v: ty::Variance) -> ty::Variance {
382 // Figure 1, column 1.
383 (ty::Covariant, ty::Covariant) => ty::Covariant,
384 (ty::Covariant, ty::Contravariant) => ty::Contravariant,
385 (ty::Covariant, ty::Invariant) => ty::Invariant,
386 (ty::Covariant, ty::Bivariant) => ty::Bivariant,
388 // Figure 1, column 2.
389 (ty::Contravariant, ty::Covariant) => ty::Contravariant,
390 (ty::Contravariant, ty::Contravariant) => ty::Covariant,
391 (ty::Contravariant, ty::Invariant) => ty::Invariant,
392 (ty::Contravariant, ty::Bivariant) => ty::Bivariant,
394 // Figure 1, column 3.
395 (ty::Invariant, _) => ty::Invariant,
397 // Figure 1, column 4.
398 (ty::Bivariant, _) => ty::Bivariant,
403 // Contains information needed to resolve types and (in the future) look up
404 // the types of AST nodes.
405 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
406 pub struct CReaderCacheKey {
411 // Flags that we track on types. These flags are propagated upwards
412 // through the type during type construction, so that we can quickly
413 // check whether the type has various kinds of types in it without
414 // recursing over the type itself.
416 pub struct TypeFlags: u32 {
417 const HAS_PARAMS = 1 << 0;
418 const HAS_TY_INFER = 1 << 1;
419 const HAS_RE_INFER = 1 << 2;
420 const HAS_RE_PLACEHOLDER = 1 << 3;
422 /// Does this have any `ReEarlyBound` regions? Used to
423 /// determine whether substitition is required, since those
424 /// represent regions that are bound in a `ty::Generics` and
425 /// hence may be substituted.
426 const HAS_RE_EARLY_BOUND = 1 << 4;
428 /// Does this have any region that "appears free" in the type?
429 /// Basically anything but `ReLateBound` and `ReErased`.
430 const HAS_FREE_REGIONS = 1 << 5;
432 /// Is an error type reachable?
433 const HAS_TY_ERR = 1 << 6;
434 const HAS_PROJECTION = 1 << 7;
436 // FIXME: Rename this to the actual property since it's used for generators too
437 const HAS_TY_CLOSURE = 1 << 8;
439 /// `true` if there are "names" of types and regions and so forth
440 /// that are local to a particular fn
441 const HAS_FREE_LOCAL_NAMES = 1 << 9;
443 /// Present if the type belongs in a local type context.
444 /// Only set for Infer other than Fresh.
445 const KEEP_IN_LOCAL_TCX = 1 << 10;
447 /// Does this have any `ReLateBound` regions? Used to check
448 /// if a global bound is safe to evaluate.
449 const HAS_RE_LATE_BOUND = 1 << 11;
451 const HAS_TY_PLACEHOLDER = 1 << 12;
453 const HAS_CT_INFER = 1 << 13;
454 const HAS_CT_PLACEHOLDER = 1 << 14;
456 const NEEDS_SUBST = TypeFlags::HAS_PARAMS.bits |
457 TypeFlags::HAS_RE_EARLY_BOUND.bits;
459 /// Flags representing the nominal content of a type,
460 /// computed by FlagsComputation. If you add a new nominal
461 /// flag, it should be added here too.
462 const NOMINAL_FLAGS = TypeFlags::HAS_PARAMS.bits |
463 TypeFlags::HAS_TY_INFER.bits |
464 TypeFlags::HAS_RE_INFER.bits |
465 TypeFlags::HAS_RE_PLACEHOLDER.bits |
466 TypeFlags::HAS_RE_EARLY_BOUND.bits |
467 TypeFlags::HAS_FREE_REGIONS.bits |
468 TypeFlags::HAS_TY_ERR.bits |
469 TypeFlags::HAS_PROJECTION.bits |
470 TypeFlags::HAS_TY_CLOSURE.bits |
471 TypeFlags::HAS_FREE_LOCAL_NAMES.bits |
472 TypeFlags::KEEP_IN_LOCAL_TCX.bits |
473 TypeFlags::HAS_RE_LATE_BOUND.bits |
474 TypeFlags::HAS_TY_PLACEHOLDER.bits |
475 TypeFlags::HAS_CT_INFER.bits |
476 TypeFlags::HAS_CT_PLACEHOLDER.bits;
480 #[allow(rustc::usage_of_ty_tykind)]
481 pub struct TyS<'tcx> {
482 pub sty: TyKind<'tcx>,
483 pub flags: TypeFlags,
485 /// This is a kind of confusing thing: it stores the smallest
488 /// (a) the binder itself captures nothing but
489 /// (b) all the late-bound things within the type are captured
490 /// by some sub-binder.
492 /// So, for a type without any late-bound things, like `u32`, this
493 /// will be *innermost*, because that is the innermost binder that
494 /// captures nothing. But for a type `&'D u32`, where `'D` is a
495 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
496 /// -- the binder itself does not capture `D`, but `D` is captured
497 /// by an inner binder.
499 /// We call this concept an "exclusive" binder `D` because all
500 /// De Bruijn indices within the type are contained within `0..D`
502 outer_exclusive_binder: ty::DebruijnIndex,
505 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
506 #[cfg(target_arch = "x86_64")]
507 static_assert_size!(TyS<'_>, 32);
509 impl<'tcx> Ord for TyS<'tcx> {
510 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
511 self.sty.cmp(&other.sty)
515 impl<'tcx> PartialOrd for TyS<'tcx> {
516 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
517 Some(self.sty.cmp(&other.sty))
521 impl<'tcx> PartialEq for TyS<'tcx> {
523 fn eq(&self, other: &TyS<'tcx>) -> bool {
527 impl<'tcx> Eq for TyS<'tcx> {}
529 impl<'tcx> Hash for TyS<'tcx> {
530 fn hash<H: Hasher>(&self, s: &mut H) {
531 (self as *const TyS<'_>).hash(s)
535 impl<'tcx> TyS<'tcx> {
536 pub fn is_primitive_ty(&self) -> bool {
543 Infer(InferTy::IntVar(_)) |
544 Infer(InferTy::FloatVar(_)) |
545 Infer(InferTy::FreshIntTy(_)) |
546 Infer(InferTy::FreshFloatTy(_)) => true,
547 Ref(_, x, _) => x.is_primitive_ty(),
552 pub fn is_suggestable(&self) -> bool {
560 Projection(..) => false,
566 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ty::TyS<'tcx> {
567 fn hash_stable<W: StableHasherResult>(&self,
568 hcx: &mut StableHashingContext<'a>,
569 hasher: &mut StableHasher<W>) {
573 // The other fields just provide fast access to information that is
574 // also contained in `sty`, so no need to hash them.
577 outer_exclusive_binder: _,
580 sty.hash_stable(hcx, hasher);
584 #[cfg_attr(not(bootstrap), rustc_diagnostic_item = "Ty")]
585 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
587 impl<'tcx> rustc_serialize::UseSpecializedEncodable for Ty<'tcx> {}
588 impl<'tcx> rustc_serialize::UseSpecializedDecodable for Ty<'tcx> {}
590 pub type CanonicalTy<'tcx> = Canonical<'tcx, Ty<'tcx>>;
593 /// A dummy type used to force `List` to by unsized without requiring fat pointers.
594 type OpaqueListContents;
597 /// A wrapper for slices with the additional invariant
598 /// that the slice is interned and no other slice with
599 /// the same contents can exist in the same context.
600 /// This means we can use pointer for both
601 /// equality comparisons and hashing.
602 /// Note: `Slice` was already taken by the `Ty`.
607 opaque: OpaqueListContents,
610 unsafe impl<T: Sync> Sync for List<T> {}
612 impl<T: Copy> List<T> {
614 fn from_arena<'tcx>(arena: &'tcx SyncDroplessArena, slice: &[T]) -> &'tcx List<T> {
615 assert!(!mem::needs_drop::<T>());
616 assert!(mem::size_of::<T>() != 0);
617 assert!(slice.len() != 0);
619 // Align up the size of the len (usize) field
620 let align = mem::align_of::<T>();
621 let align_mask = align - 1;
622 let offset = mem::size_of::<usize>();
623 let offset = (offset + align_mask) & !align_mask;
625 let size = offset + slice.len() * mem::size_of::<T>();
627 let mem = arena.alloc_raw(
629 cmp::max(mem::align_of::<T>(), mem::align_of::<usize>()));
631 let result = &mut *(mem.as_mut_ptr() as *mut List<T>);
633 result.len = slice.len();
635 // Write the elements
636 let arena_slice = slice::from_raw_parts_mut(result.data.as_mut_ptr(), result.len);
637 arena_slice.copy_from_slice(slice);
644 impl<T: fmt::Debug> fmt::Debug for List<T> {
645 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
650 impl<T: Encodable> Encodable for List<T> {
652 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
657 impl<T> Ord for List<T> where T: Ord {
658 fn cmp(&self, other: &List<T>) -> Ordering {
659 if self == other { Ordering::Equal } else {
660 <[T] as Ord>::cmp(&**self, &**other)
665 impl<T> PartialOrd for List<T> where T: PartialOrd {
666 fn partial_cmp(&self, other: &List<T>) -> Option<Ordering> {
667 if self == other { Some(Ordering::Equal) } else {
668 <[T] as PartialOrd>::partial_cmp(&**self, &**other)
673 impl<T: PartialEq> PartialEq for List<T> {
675 fn eq(&self, other: &List<T>) -> bool {
679 impl<T: Eq> Eq for List<T> {}
681 impl<T> Hash for List<T> {
683 fn hash<H: Hasher>(&self, s: &mut H) {
684 (self as *const List<T>).hash(s)
688 impl<T> Deref for List<T> {
691 fn deref(&self) -> &[T] {
693 slice::from_raw_parts(self.data.as_ptr(), self.len)
698 impl<'a, T> IntoIterator for &'a List<T> {
700 type IntoIter = <&'a [T] as IntoIterator>::IntoIter;
702 fn into_iter(self) -> Self::IntoIter {
707 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx List<Ty<'tcx>> {}
711 pub fn empty<'a>() -> &'a List<T> {
712 #[repr(align(64), C)]
713 struct EmptySlice([u8; 64]);
714 static EMPTY_SLICE: EmptySlice = EmptySlice([0; 64]);
715 assert!(mem::align_of::<T>() <= 64);
717 &*(&EMPTY_SLICE as *const _ as *const List<T>)
722 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
723 pub struct UpvarPath {
724 pub hir_id: hir::HirId,
727 /// Upvars do not get their own `NodeId`. Instead, we use the pair of
728 /// the original var ID (that is, the root variable that is referenced
729 /// by the upvar) and the ID of the closure expression.
730 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
732 pub var_path: UpvarPath,
733 pub closure_expr_id: LocalDefId,
736 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, Copy, HashStable)]
737 pub enum BorrowKind {
738 /// Data must be immutable and is aliasable.
741 /// Data must be immutable but not aliasable. This kind of borrow
742 /// cannot currently be expressed by the user and is used only in
743 /// implicit closure bindings. It is needed when the closure
744 /// is borrowing or mutating a mutable referent, e.g.:
746 /// let x: &mut isize = ...;
747 /// let y = || *x += 5;
749 /// If we were to try to translate this closure into a more explicit
750 /// form, we'd encounter an error with the code as written:
752 /// struct Env { x: & &mut isize }
753 /// let x: &mut isize = ...;
754 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
755 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
757 /// This is then illegal because you cannot mutate a `&mut` found
758 /// in an aliasable location. To solve, you'd have to translate with
759 /// an `&mut` borrow:
761 /// struct Env { x: & &mut isize }
762 /// let x: &mut isize = ...;
763 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
764 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
766 /// Now the assignment to `**env.x` is legal, but creating a
767 /// mutable pointer to `x` is not because `x` is not mutable. We
768 /// could fix this by declaring `x` as `let mut x`. This is ok in
769 /// user code, if awkward, but extra weird for closures, since the
770 /// borrow is hidden.
772 /// So we introduce a "unique imm" borrow -- the referent is
773 /// immutable, but not aliasable. This solves the problem. For
774 /// simplicity, we don't give users the way to express this
775 /// borrow, it's just used when translating closures.
778 /// Data is mutable and not aliasable.
782 /// Information describing the capture of an upvar. This is computed
783 /// during `typeck`, specifically by `regionck`.
784 #[derive(PartialEq, Clone, Debug, Copy, RustcEncodable, RustcDecodable, HashStable)]
785 pub enum UpvarCapture<'tcx> {
786 /// Upvar is captured by value. This is always true when the
787 /// closure is labeled `move`, but can also be true in other cases
788 /// depending on inference.
791 /// Upvar is captured by reference.
792 ByRef(UpvarBorrow<'tcx>),
795 #[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable, HashStable)]
796 pub struct UpvarBorrow<'tcx> {
797 /// The kind of borrow: by-ref upvars have access to shared
798 /// immutable borrows, which are not part of the normal language
800 pub kind: BorrowKind,
802 /// Region of the resulting reference.
803 pub region: ty::Region<'tcx>,
806 pub type UpvarListMap = FxHashMap<DefId, FxIndexMap<hir::HirId, UpvarId>>;
807 pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
809 #[derive(Copy, Clone)]
810 pub struct ClosureUpvar<'tcx> {
816 #[derive(Clone, Copy, PartialEq, Eq)]
817 pub enum IntVarValue {
819 UintType(ast::UintTy),
822 #[derive(Clone, Copy, PartialEq, Eq)]
823 pub struct FloatVarValue(pub ast::FloatTy);
825 impl ty::EarlyBoundRegion {
826 pub fn to_bound_region(&self) -> ty::BoundRegion {
827 ty::BoundRegion::BrNamed(self.def_id, self.name)
830 /// Does this early bound region have a name? Early bound regions normally
831 /// always have names except when using anonymous lifetimes (`'_`).
832 pub fn has_name(&self) -> bool {
833 self.name != kw::UnderscoreLifetime.as_interned_str()
837 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
838 pub enum GenericParamDefKind {
842 object_lifetime_default: ObjectLifetimeDefault,
843 synthetic: Option<hir::SyntheticTyParamKind>,
848 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
849 pub struct GenericParamDef {
850 pub name: InternedString,
854 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
855 /// on generic parameter `'a`/`T`, asserts data behind the parameter
856 /// `'a`/`T` won't be accessed during the parent type's `Drop` impl.
857 pub pure_wrt_drop: bool,
859 pub kind: GenericParamDefKind,
862 impl GenericParamDef {
863 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
864 if let GenericParamDefKind::Lifetime = self.kind {
865 ty::EarlyBoundRegion {
871 bug!("cannot convert a non-lifetime parameter def to an early bound region")
875 pub fn to_bound_region(&self) -> ty::BoundRegion {
876 if let GenericParamDefKind::Lifetime = self.kind {
877 self.to_early_bound_region_data().to_bound_region()
879 bug!("cannot convert a non-lifetime parameter def to an early bound region")
885 pub struct GenericParamCount {
886 pub lifetimes: usize,
891 /// Information about the formal type/lifetime parameters associated
892 /// with an item or method. Analogous to `hir::Generics`.
894 /// The ordering of parameters is the same as in `Subst` (excluding child generics):
895 /// `Self` (optionally), `Lifetime` params..., `Type` params...
896 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
897 pub struct Generics {
898 pub parent: Option<DefId>,
899 pub parent_count: usize,
900 pub params: Vec<GenericParamDef>,
902 /// Reverse map to the `index` field of each `GenericParamDef`.
903 #[stable_hasher(ignore)]
904 pub param_def_id_to_index: FxHashMap<DefId, u32>,
907 pub has_late_bound_regions: Option<Span>,
910 impl<'tcx> Generics {
911 pub fn count(&self) -> usize {
912 self.parent_count + self.params.len()
915 pub fn own_counts(&self) -> GenericParamCount {
916 // We could cache this as a property of `GenericParamCount`, but
917 // the aim is to refactor this away entirely eventually and the
918 // presence of this method will be a constant reminder.
919 let mut own_counts: GenericParamCount = Default::default();
921 for param in &self.params {
923 GenericParamDefKind::Lifetime => own_counts.lifetimes += 1,
924 GenericParamDefKind::Type { .. } => own_counts.types += 1,
925 GenericParamDefKind::Const => own_counts.consts += 1,
932 pub fn requires_monomorphization(&self, tcx: TyCtxt<'tcx>) -> bool {
933 if self.own_requires_monomorphization() {
937 if let Some(parent_def_id) = self.parent {
938 let parent = tcx.generics_of(parent_def_id);
939 parent.requires_monomorphization(tcx)
945 pub fn own_requires_monomorphization(&self) -> bool {
946 for param in &self.params {
948 GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true,
949 GenericParamDefKind::Lifetime => {}
957 param: &EarlyBoundRegion,
959 ) -> &'tcx GenericParamDef {
960 if let Some(index) = param.index.checked_sub(self.parent_count as u32) {
961 let param = &self.params[index as usize];
963 GenericParamDefKind::Lifetime => param,
964 _ => bug!("expected lifetime parameter, but found another generic parameter")
967 tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?"))
968 .region_param(param, tcx)
972 /// Returns the `GenericParamDef` associated with this `ParamTy`.
973 pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
974 if let Some(index) = param.index.checked_sub(self.parent_count as u32) {
975 let param = &self.params[index as usize];
977 GenericParamDefKind::Type { .. } => param,
978 _ => bug!("expected type parameter, but found another generic parameter")
981 tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?"))
982 .type_param(param, tcx)
986 /// Returns the `ConstParameterDef` associated with this `ParamConst`.
987 pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef {
988 if let Some(index) = param.index.checked_sub(self.parent_count as u32) {
989 let param = &self.params[index as usize];
991 GenericParamDefKind::Const => param,
992 _ => bug!("expected const parameter, but found another generic parameter")
995 tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
996 .const_param(param, tcx)
1001 /// Bounds on generics.
1002 #[derive(Clone, Default, Debug, HashStable)]
1003 pub struct GenericPredicates<'tcx> {
1004 pub parent: Option<DefId>,
1005 pub predicates: Vec<(Predicate<'tcx>, Span)>,
1008 impl<'tcx> rustc_serialize::UseSpecializedEncodable for GenericPredicates<'tcx> {}
1009 impl<'tcx> rustc_serialize::UseSpecializedDecodable for GenericPredicates<'tcx> {}
1011 impl<'tcx> GenericPredicates<'tcx> {
1015 substs: SubstsRef<'tcx>,
1016 ) -> InstantiatedPredicates<'tcx> {
1017 let mut instantiated = InstantiatedPredicates::empty();
1018 self.instantiate_into(tcx, &mut instantiated, substs);
1022 pub fn instantiate_own(
1025 substs: SubstsRef<'tcx>,
1026 ) -> InstantiatedPredicates<'tcx> {
1027 InstantiatedPredicates {
1028 predicates: self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)).collect(),
1032 fn instantiate_into(
1035 instantiated: &mut InstantiatedPredicates<'tcx>,
1036 substs: SubstsRef<'tcx>,
1038 if let Some(def_id) = self.parent {
1039 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
1041 instantiated.predicates.extend(
1042 self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)),
1046 pub fn instantiate_identity(&self, tcx: TyCtxt<'tcx>) -> InstantiatedPredicates<'tcx> {
1047 let mut instantiated = InstantiatedPredicates::empty();
1048 self.instantiate_identity_into(tcx, &mut instantiated);
1052 fn instantiate_identity_into(
1055 instantiated: &mut InstantiatedPredicates<'tcx>,
1057 if let Some(def_id) = self.parent {
1058 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
1060 instantiated.predicates.extend(self.predicates.iter().map(|&(p, _)| p))
1063 pub fn instantiate_supertrait(
1066 poly_trait_ref: &ty::PolyTraitRef<'tcx>,
1067 ) -> InstantiatedPredicates<'tcx> {
1068 assert_eq!(self.parent, None);
1069 InstantiatedPredicates {
1070 predicates: self.predicates.iter().map(|(pred, _)| {
1071 pred.subst_supertrait(tcx, poly_trait_ref)
1077 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
1078 pub enum Predicate<'tcx> {
1079 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
1080 /// the `Self` type of the trait reference and `A`, `B`, and `C`
1081 /// would be the type parameters.
1082 Trait(PolyTraitPredicate<'tcx>),
1085 RegionOutlives(PolyRegionOutlivesPredicate<'tcx>),
1088 TypeOutlives(PolyTypeOutlivesPredicate<'tcx>),
1090 /// `where <T as TraitRef>::Name == X`, approximately.
1091 /// See the `ProjectionPredicate` struct for details.
1092 Projection(PolyProjectionPredicate<'tcx>),
1094 /// No syntax: `T` well-formed.
1095 WellFormed(Ty<'tcx>),
1097 /// Trait must be object-safe.
1100 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
1101 /// for some substitutions `...` and `T` being a closure type.
1102 /// Satisfied (or refuted) once we know the closure's kind.
1103 ClosureKind(DefId, ClosureSubsts<'tcx>, ClosureKind),
1106 Subtype(PolySubtypePredicate<'tcx>),
1108 /// Constant initializer must evaluate successfully.
1109 ConstEvaluatable(DefId, SubstsRef<'tcx>),
1112 /// The crate outlives map is computed during typeck and contains the
1113 /// outlives of every item in the local crate. You should not use it
1114 /// directly, because to do so will make your pass dependent on the
1115 /// HIR of every item in the local crate. Instead, use
1116 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
1118 #[derive(HashStable)]
1119 pub struct CratePredicatesMap<'tcx> {
1120 /// For each struct with outlive bounds, maps to a vector of the
1121 /// predicate of its outlive bounds. If an item has no outlives
1122 /// bounds, it will have no entry.
1123 pub predicates: FxHashMap<DefId, &'tcx [ty::Predicate<'tcx>]>,
1126 impl<'tcx> AsRef<Predicate<'tcx>> for Predicate<'tcx> {
1127 fn as_ref(&self) -> &Predicate<'tcx> {
1132 impl<'tcx> Predicate<'tcx> {
1133 /// Performs a substitution suitable for going from a
1134 /// poly-trait-ref to supertraits that must hold if that
1135 /// poly-trait-ref holds. This is slightly different from a normal
1136 /// substitution in terms of what happens with bound regions. See
1137 /// lengthy comment below for details.
1138 pub fn subst_supertrait(
1141 trait_ref: &ty::PolyTraitRef<'tcx>,
1142 ) -> ty::Predicate<'tcx> {
1143 // The interaction between HRTB and supertraits is not entirely
1144 // obvious. Let me walk you (and myself) through an example.
1146 // Let's start with an easy case. Consider two traits:
1148 // trait Foo<'a>: Bar<'a,'a> { }
1149 // trait Bar<'b,'c> { }
1151 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
1152 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
1153 // knew that `Foo<'x>` (for any 'x) then we also know that
1154 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
1155 // normal substitution.
1157 // In terms of why this is sound, the idea is that whenever there
1158 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
1159 // holds. So if there is an impl of `T:Foo<'a>` that applies to
1160 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
1163 // Another example to be careful of is this:
1165 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
1166 // trait Bar1<'b,'c> { }
1168 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
1169 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
1170 // reason is similar to the previous example: any impl of
1171 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
1172 // basically we would want to collapse the bound lifetimes from
1173 // the input (`trait_ref`) and the supertraits.
1175 // To achieve this in practice is fairly straightforward. Let's
1176 // consider the more complicated scenario:
1178 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
1179 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
1180 // where both `'x` and `'b` would have a DB index of 1.
1181 // The substitution from the input trait-ref is therefore going to be
1182 // `'a => 'x` (where `'x` has a DB index of 1).
1183 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1184 // early-bound parameter and `'b' is a late-bound parameter with a
1186 // - If we replace `'a` with `'x` from the input, it too will have
1187 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1188 // just as we wanted.
1190 // There is only one catch. If we just apply the substitution `'a
1191 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1192 // adjust the DB index because we substituting into a binder (it
1193 // tries to be so smart...) resulting in `for<'x> for<'b>
1194 // Bar1<'x,'b>` (we have no syntax for this, so use your
1195 // imagination). Basically the 'x will have DB index of 2 and 'b
1196 // will have DB index of 1. Not quite what we want. So we apply
1197 // the substitution to the *contents* of the trait reference,
1198 // rather than the trait reference itself (put another way, the
1199 // substitution code expects equal binding levels in the values
1200 // from the substitution and the value being substituted into, and
1201 // this trick achieves that).
1203 let substs = &trait_ref.skip_binder().substs;
1205 Predicate::Trait(ref binder) =>
1206 Predicate::Trait(binder.map_bound(|data| data.subst(tcx, substs))),
1207 Predicate::Subtype(ref binder) =>
1208 Predicate::Subtype(binder.map_bound(|data| data.subst(tcx, substs))),
1209 Predicate::RegionOutlives(ref binder) =>
1210 Predicate::RegionOutlives(binder.map_bound(|data| data.subst(tcx, substs))),
1211 Predicate::TypeOutlives(ref binder) =>
1212 Predicate::TypeOutlives(binder.map_bound(|data| data.subst(tcx, substs))),
1213 Predicate::Projection(ref binder) =>
1214 Predicate::Projection(binder.map_bound(|data| data.subst(tcx, substs))),
1215 Predicate::WellFormed(data) =>
1216 Predicate::WellFormed(data.subst(tcx, substs)),
1217 Predicate::ObjectSafe(trait_def_id) =>
1218 Predicate::ObjectSafe(trait_def_id),
1219 Predicate::ClosureKind(closure_def_id, closure_substs, kind) =>
1220 Predicate::ClosureKind(closure_def_id, closure_substs.subst(tcx, substs), kind),
1221 Predicate::ConstEvaluatable(def_id, const_substs) =>
1222 Predicate::ConstEvaluatable(def_id, const_substs.subst(tcx, substs)),
1227 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
1228 pub struct TraitPredicate<'tcx> {
1229 pub trait_ref: TraitRef<'tcx>
1232 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1234 impl<'tcx> TraitPredicate<'tcx> {
1235 pub fn def_id(&self) -> DefId {
1236 self.trait_ref.def_id
1239 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
1240 self.trait_ref.input_types()
1243 pub fn self_ty(&self) -> Ty<'tcx> {
1244 self.trait_ref.self_ty()
1248 impl<'tcx> PolyTraitPredicate<'tcx> {
1249 pub fn def_id(&self) -> DefId {
1250 // Ok to skip binder since trait `DefId` does not care about regions.
1251 self.skip_binder().def_id()
1255 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1256 Hash, Debug, RustcEncodable, RustcDecodable, HashStable)]
1257 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
1258 pub type PolyOutlivesPredicate<A, B> = ty::Binder<OutlivesPredicate<A, B>>;
1259 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
1260 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1261 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>;
1262 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>;
1264 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, HashStable)]
1265 pub struct SubtypePredicate<'tcx> {
1266 pub a_is_expected: bool,
1270 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1272 /// This kind of predicate has no *direct* correspondent in the
1273 /// syntax, but it roughly corresponds to the syntactic forms:
1275 /// 1. `T: TraitRef<..., Item = Type>`
1276 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1278 /// In particular, form #1 is "desugared" to the combination of a
1279 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1280 /// predicates. Form #2 is a broader form in that it also permits
1281 /// equality between arbitrary types. Processing an instance of
1282 /// Form #2 eventually yields one of these `ProjectionPredicate`
1283 /// instances to normalize the LHS.
1284 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
1285 pub struct ProjectionPredicate<'tcx> {
1286 pub projection_ty: ProjectionTy<'tcx>,
1290 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1292 impl<'tcx> PolyProjectionPredicate<'tcx> {
1293 /// Returns the `DefId` of the associated item being projected.
1294 pub fn item_def_id(&self) -> DefId {
1295 self.skip_binder().projection_ty.item_def_id
1299 pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'_>) -> PolyTraitRef<'tcx> {
1300 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1301 // `self.0.trait_ref` is permitted to have escaping regions.
1302 // This is because here `self` has a `Binder` and so does our
1303 // return value, so we are preserving the number of binding
1305 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1308 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1309 self.map_bound(|predicate| predicate.ty)
1312 /// The `DefId` of the `TraitItem` for the associated type.
1314 /// Note that this is not the `DefId` of the `TraitRef` containing this
1315 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1316 pub fn projection_def_id(&self) -> DefId {
1317 // Ok to skip binder since trait `DefId` does not care about regions.
1318 self.skip_binder().projection_ty.item_def_id
1322 pub trait ToPolyTraitRef<'tcx> {
1323 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1326 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1327 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1328 ty::Binder::dummy(self.clone())
1332 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1333 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1334 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1338 pub trait ToPredicate<'tcx> {
1339 fn to_predicate(&self) -> Predicate<'tcx>;
1342 impl<'tcx> ToPredicate<'tcx> for TraitRef<'tcx> {
1343 fn to_predicate(&self) -> Predicate<'tcx> {
1344 ty::Predicate::Trait(ty::Binder::dummy(ty::TraitPredicate {
1345 trait_ref: self.clone()
1350 impl<'tcx> ToPredicate<'tcx> for PolyTraitRef<'tcx> {
1351 fn to_predicate(&self) -> Predicate<'tcx> {
1352 ty::Predicate::Trait(self.to_poly_trait_predicate())
1356 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1357 fn to_predicate(&self) -> Predicate<'tcx> {
1358 Predicate::RegionOutlives(self.clone())
1362 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1363 fn to_predicate(&self) -> Predicate<'tcx> {
1364 Predicate::TypeOutlives(self.clone())
1368 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1369 fn to_predicate(&self) -> Predicate<'tcx> {
1370 Predicate::Projection(self.clone())
1374 // A custom iterator used by `Predicate::walk_tys`.
1375 enum WalkTysIter<'tcx, I, J, K>
1376 where I: Iterator<Item = Ty<'tcx>>,
1377 J: Iterator<Item = Ty<'tcx>>,
1378 K: Iterator<Item = Ty<'tcx>>
1382 Two(Ty<'tcx>, Ty<'tcx>),
1388 impl<'tcx, I, J, K> Iterator for WalkTysIter<'tcx, I, J, K>
1389 where I: Iterator<Item = Ty<'tcx>>,
1390 J: Iterator<Item = Ty<'tcx>>,
1391 K: Iterator<Item = Ty<'tcx>>
1393 type Item = Ty<'tcx>;
1395 fn next(&mut self) -> Option<Ty<'tcx>> {
1397 WalkTysIter::None => None,
1398 WalkTysIter::One(item) => {
1399 *self = WalkTysIter::None;
1402 WalkTysIter::Two(item1, item2) => {
1403 *self = WalkTysIter::One(item2);
1406 WalkTysIter::Types(ref mut iter) => {
1409 WalkTysIter::InputTypes(ref mut iter) => {
1412 WalkTysIter::ProjectionTypes(ref mut iter) => {
1419 impl<'tcx> Predicate<'tcx> {
1420 /// Iterates over the types in this predicate. Note that in all
1421 /// cases this is skipping over a binder, so late-bound regions
1422 /// with depth 0 are bound by the predicate.
1423 pub fn walk_tys(&'a self) -> impl Iterator<Item = Ty<'tcx>> + 'a {
1425 ty::Predicate::Trait(ref data) => {
1426 WalkTysIter::InputTypes(data.skip_binder().input_types())
1428 ty::Predicate::Subtype(binder) => {
1429 let SubtypePredicate { a, b, a_is_expected: _ } = binder.skip_binder();
1430 WalkTysIter::Two(a, b)
1432 ty::Predicate::TypeOutlives(binder) => {
1433 WalkTysIter::One(binder.skip_binder().0)
1435 ty::Predicate::RegionOutlives(..) => {
1438 ty::Predicate::Projection(ref data) => {
1439 let inner = data.skip_binder();
1440 WalkTysIter::ProjectionTypes(
1441 inner.projection_ty.substs.types().chain(Some(inner.ty)))
1443 ty::Predicate::WellFormed(data) => {
1444 WalkTysIter::One(data)
1446 ty::Predicate::ObjectSafe(_trait_def_id) => {
1449 ty::Predicate::ClosureKind(_closure_def_id, closure_substs, _kind) => {
1450 WalkTysIter::Types(closure_substs.substs.types())
1452 ty::Predicate::ConstEvaluatable(_, substs) => {
1453 WalkTysIter::Types(substs.types())
1458 pub fn to_opt_poly_trait_ref(&self) -> Option<PolyTraitRef<'tcx>> {
1460 Predicate::Trait(ref t) => {
1461 Some(t.to_poly_trait_ref())
1463 Predicate::Projection(..) |
1464 Predicate::Subtype(..) |
1465 Predicate::RegionOutlives(..) |
1466 Predicate::WellFormed(..) |
1467 Predicate::ObjectSafe(..) |
1468 Predicate::ClosureKind(..) |
1469 Predicate::TypeOutlives(..) |
1470 Predicate::ConstEvaluatable(..) => {
1476 pub fn to_opt_type_outlives(&self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1478 Predicate::TypeOutlives(data) => {
1481 Predicate::Trait(..) |
1482 Predicate::Projection(..) |
1483 Predicate::Subtype(..) |
1484 Predicate::RegionOutlives(..) |
1485 Predicate::WellFormed(..) |
1486 Predicate::ObjectSafe(..) |
1487 Predicate::ClosureKind(..) |
1488 Predicate::ConstEvaluatable(..) => {
1495 /// Represents the bounds declared on a particular set of type
1496 /// parameters. Should eventually be generalized into a flag list of
1497 /// where-clauses. You can obtain a `InstantiatedPredicates` list from a
1498 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1499 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1500 /// the `GenericPredicates` are expressed in terms of the bound type
1501 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1502 /// represented a set of bounds for some particular instantiation,
1503 /// meaning that the generic parameters have been substituted with
1508 /// struct Foo<T, U: Bar<T>> { ... }
1510 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1511 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1512 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1513 /// [usize:Bar<isize>]]`.
1514 #[derive(Clone, Debug)]
1515 pub struct InstantiatedPredicates<'tcx> {
1516 pub predicates: Vec<Predicate<'tcx>>,
1519 impl<'tcx> InstantiatedPredicates<'tcx> {
1520 pub fn empty() -> InstantiatedPredicates<'tcx> {
1521 InstantiatedPredicates { predicates: vec![] }
1524 pub fn is_empty(&self) -> bool {
1525 self.predicates.is_empty()
1530 /// "Universes" are used during type- and trait-checking in the
1531 /// presence of `for<..>` binders to control what sets of names are
1532 /// visible. Universes are arranged into a tree: the root universe
1533 /// contains names that are always visible. Each child then adds a new
1534 /// set of names that are visible, in addition to those of its parent.
1535 /// We say that the child universe "extends" the parent universe with
1538 /// To make this more concrete, consider this program:
1542 /// fn bar<T>(x: T) {
1543 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1547 /// The struct name `Foo` is in the root universe U0. But the type
1548 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1549 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1550 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1551 /// region `'a` is in a universe U2 that extends U1, because we can
1552 /// name it inside the fn type but not outside.
1554 /// Universes are used to do type- and trait-checking around these
1555 /// "forall" binders (also called **universal quantification**). The
1556 /// idea is that when, in the body of `bar`, we refer to `T` as a
1557 /// type, we aren't referring to any type in particular, but rather a
1558 /// kind of "fresh" type that is distinct from all other types we have
1559 /// actually declared. This is called a **placeholder** type, and we
1560 /// use universes to talk about this. In other words, a type name in
1561 /// universe 0 always corresponds to some "ground" type that the user
1562 /// declared, but a type name in a non-zero universe is a placeholder
1563 /// type -- an idealized representative of "types in general" that we
1564 /// use for checking generic functions.
1565 pub struct UniverseIndex {
1566 DEBUG_FORMAT = "U{}",
1570 impl_stable_hash_for!(struct UniverseIndex { private });
1572 impl UniverseIndex {
1573 pub const ROOT: UniverseIndex = UniverseIndex::from_u32_const(0);
1575 /// Returns the "next" universe index in order -- this new index
1576 /// is considered to extend all previous universes. This
1577 /// corresponds to entering a `forall` quantifier. So, for
1578 /// example, suppose we have this type in universe `U`:
1581 /// for<'a> fn(&'a u32)
1584 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1585 /// new universe that extends `U` -- in this new universe, we can
1586 /// name the region `'a`, but that region was not nameable from
1587 /// `U` because it was not in scope there.
1588 pub fn next_universe(self) -> UniverseIndex {
1589 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1592 /// Returns `true` if `self` can name a name from `other` -- in other words,
1593 /// if the set of names in `self` is a superset of those in
1594 /// `other` (`self >= other`).
1595 pub fn can_name(self, other: UniverseIndex) -> bool {
1596 self.private >= other.private
1599 /// Returns `true` if `self` cannot name some names from `other` -- in other
1600 /// words, if the set of names in `self` is a strict subset of
1601 /// those in `other` (`self < other`).
1602 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1603 self.private < other.private
1607 /// The "placeholder index" fully defines a placeholder region.
1608 /// Placeholder regions are identified by both a **universe** as well
1609 /// as a "bound-region" within that universe. The `bound_region` is
1610 /// basically a name -- distinct bound regions within the same
1611 /// universe are just two regions with an unknown relationship to one
1613 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1614 pub struct Placeholder<T> {
1615 pub universe: UniverseIndex,
1619 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1621 T: HashStable<StableHashingContext<'a>>,
1623 fn hash_stable<W: StableHasherResult>(
1625 hcx: &mut StableHashingContext<'a>,
1626 hasher: &mut StableHasher<W>
1628 self.universe.hash_stable(hcx, hasher);
1629 self.name.hash_stable(hcx, hasher);
1633 pub type PlaceholderRegion = Placeholder<BoundRegion>;
1635 pub type PlaceholderType = Placeholder<BoundVar>;
1637 pub type PlaceholderConst = Placeholder<BoundVar>;
1639 /// When type checking, we use the `ParamEnv` to track
1640 /// details about the set of where-clauses that are in scope at this
1641 /// particular point.
1642 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1643 pub struct ParamEnv<'tcx> {
1644 /// `Obligation`s that the caller must satisfy. This is basically
1645 /// the set of bounds on the in-scope type parameters, translated
1646 /// into `Obligation`s, and elaborated and normalized.
1647 pub caller_bounds: &'tcx List<ty::Predicate<'tcx>>,
1649 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1650 /// want `Reveal::All` -- note that this is always paired with an
1651 /// empty environment. To get that, use `ParamEnv::reveal()`.
1652 pub reveal: traits::Reveal,
1654 /// If this `ParamEnv` comes from a call to `tcx.param_env(def_id)`,
1655 /// register that `def_id` (useful for transitioning to the chalk trait
1657 pub def_id: Option<DefId>,
1660 impl<'tcx> ParamEnv<'tcx> {
1661 /// Construct a trait environment suitable for contexts where
1662 /// there are no where-clauses in scope. Hidden types (like `impl
1663 /// Trait`) are left hidden, so this is suitable for ordinary
1666 pub fn empty() -> Self {
1667 Self::new(List::empty(), Reveal::UserFacing, None)
1670 /// Construct a trait environment with no where-clauses in scope
1671 /// where the values of all `impl Trait` and other hidden types
1672 /// are revealed. This is suitable for monomorphized, post-typeck
1673 /// environments like codegen or doing optimizations.
1675 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1676 /// or invoke `param_env.with_reveal_all()`.
1678 pub fn reveal_all() -> Self {
1679 Self::new(List::empty(), Reveal::All, None)
1682 /// Construct a trait environment with the given set of predicates.
1685 caller_bounds: &'tcx List<ty::Predicate<'tcx>>,
1687 def_id: Option<DefId>
1689 ty::ParamEnv { caller_bounds, reveal, def_id }
1692 /// Returns a new parameter environment with the same clauses, but
1693 /// which "reveals" the true results of projections in all cases
1694 /// (even for associated types that are specializable). This is
1695 /// the desired behavior during codegen and certain other special
1696 /// contexts; normally though we want to use `Reveal::UserFacing`,
1697 /// which is the default.
1698 pub fn with_reveal_all(self) -> Self {
1699 ty::ParamEnv { reveal: Reveal::All, ..self }
1702 /// Returns this same environment but with no caller bounds.
1703 pub fn without_caller_bounds(self) -> Self {
1704 ty::ParamEnv { caller_bounds: List::empty(), ..self }
1707 /// Creates a suitable environment in which to perform trait
1708 /// queries on the given value. When type-checking, this is simply
1709 /// the pair of the environment plus value. But when reveal is set to
1710 /// All, then if `value` does not reference any type parameters, we will
1711 /// pair it with the empty environment. This improves caching and is generally
1714 /// N.B., we preserve the environment when type-checking because it
1715 /// is possible for the user to have wacky where-clauses like
1716 /// `where Box<u32>: Copy`, which are clearly never
1717 /// satisfiable. We generally want to behave as if they were true,
1718 /// although the surrounding function is never reachable.
1719 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1721 Reveal::UserFacing => {
1729 if value.has_placeholders()
1730 || value.needs_infer()
1731 || value.has_param_types()
1739 param_env: self.without_caller_bounds(),
1748 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1749 pub struct ParamEnvAnd<'tcx, T> {
1750 pub param_env: ParamEnv<'tcx>,
1754 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1755 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1756 (self.param_env, self.value)
1760 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1762 T: HashStable<StableHashingContext<'a>>,
1764 fn hash_stable<W: StableHasherResult>(&self,
1765 hcx: &mut StableHashingContext<'a>,
1766 hasher: &mut StableHasher<W>) {
1772 param_env.hash_stable(hcx, hasher);
1773 value.hash_stable(hcx, hasher);
1777 #[derive(Copy, Clone, Debug, HashStable)]
1778 pub struct Destructor {
1779 /// The `DefId` of the destructor method
1784 #[derive(HashStable)]
1785 pub struct AdtFlags: u32 {
1786 const NO_ADT_FLAGS = 0;
1787 /// Indicates whether the ADT is an enum.
1788 const IS_ENUM = 1 << 0;
1789 /// Indicates whether the ADT is a union.
1790 const IS_UNION = 1 << 1;
1791 /// Indicates whether the ADT is a struct.
1792 const IS_STRUCT = 1 << 2;
1793 /// Indicates whether the ADT is a struct and has a constructor.
1794 const HAS_CTOR = 1 << 3;
1795 /// Indicates whether the type is a `PhantomData`.
1796 const IS_PHANTOM_DATA = 1 << 4;
1797 /// Indicates whether the type has a `#[fundamental]` attribute.
1798 const IS_FUNDAMENTAL = 1 << 5;
1799 /// Indicates whether the type is a `Box`.
1800 const IS_BOX = 1 << 6;
1801 /// Indicates whether the type is an `Arc`.
1802 const IS_ARC = 1 << 7;
1803 /// Indicates whether the type is an `Rc`.
1804 const IS_RC = 1 << 8;
1805 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
1806 /// (i.e., this flag is never set unless this ADT is an enum).
1807 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 9;
1812 #[derive(HashStable)]
1813 pub struct VariantFlags: u32 {
1814 const NO_VARIANT_FLAGS = 0;
1815 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1816 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1820 /// Definition of a variant -- a struct's fields or a enum variant.
1822 pub struct VariantDef {
1823 /// `DefId` that identifies the variant itself.
1824 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1826 /// `DefId` that identifies the variant's constructor.
1827 /// If this variant is a struct variant, then this is `None`.
1828 pub ctor_def_id: Option<DefId>,
1829 /// Variant or struct name.
1831 /// Discriminant of this variant.
1832 pub discr: VariantDiscr,
1833 /// Fields of this variant.
1834 pub fields: Vec<FieldDef>,
1835 /// Type of constructor of variant.
1836 pub ctor_kind: CtorKind,
1837 /// Flags of the variant (e.g. is field list non-exhaustive)?
1838 flags: VariantFlags,
1839 /// Variant is obtained as part of recovering from a syntactic error.
1840 /// May be incomplete or bogus.
1841 pub recovered: bool,
1844 impl<'tcx> VariantDef {
1845 /// Creates a new `VariantDef`.
1847 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1848 /// represents an enum variant).
1850 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1851 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1853 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1854 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1855 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1856 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1857 /// built-in trait), and we do not want to load attributes twice.
1859 /// If someone speeds up attribute loading to not be a performance concern, they can
1860 /// remove this hack and use the constructor `DefId` everywhere.
1864 variant_did: Option<DefId>,
1865 ctor_def_id: Option<DefId>,
1866 discr: VariantDiscr,
1867 fields: Vec<FieldDef>,
1868 ctor_kind: CtorKind,
1874 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1875 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1876 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1879 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1880 if adt_kind == AdtKind::Struct && tcx.has_attr(parent_did, sym::non_exhaustive) {
1881 debug!("found non-exhaustive field list for {:?}", parent_did);
1882 flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1883 } else if let Some(variant_did) = variant_did {
1884 if tcx.has_attr(variant_did, sym::non_exhaustive) {
1885 debug!("found non-exhaustive field list for {:?}", variant_did);
1886 flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1891 def_id: variant_did.unwrap_or(parent_did),
1902 /// Is this field list non-exhaustive?
1904 pub fn is_field_list_non_exhaustive(&self) -> bool {
1905 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1909 impl_stable_hash_for!(struct VariantDef {
1912 ident -> (ident.name),
1920 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
1921 pub enum VariantDiscr {
1922 /// Explicit value for this variant, i.e., `X = 123`.
1923 /// The `DefId` corresponds to the embedded constant.
1926 /// The previous variant's discriminant plus one.
1927 /// For efficiency reasons, the distance from the
1928 /// last `Explicit` discriminant is being stored,
1929 /// or `0` for the first variant, if it has none.
1933 #[derive(Debug, HashStable)]
1934 pub struct FieldDef {
1936 #[stable_hasher(project(name))]
1938 pub vis: Visibility,
1941 /// The definition of an abstract data type -- a struct or enum.
1943 /// These are all interned (by `intern_adt_def`) into the `adt_defs` table.
1945 /// `DefId` of the struct, enum or union item.
1947 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
1948 pub variants: IndexVec<self::layout::VariantIdx, VariantDef>,
1949 /// Flags of the ADT (e.g. is this a struct? is this non-exhaustive?)
1951 /// Repr options provided by the user.
1952 pub repr: ReprOptions,
1955 impl PartialOrd for AdtDef {
1956 fn partial_cmp(&self, other: &AdtDef) -> Option<Ordering> {
1957 Some(self.cmp(&other))
1961 /// There should be only one AdtDef for each `did`, therefore
1962 /// it is fine to implement `Ord` only based on `did`.
1963 impl Ord for AdtDef {
1964 fn cmp(&self, other: &AdtDef) -> Ordering {
1965 self.did.cmp(&other.did)
1969 impl PartialEq for AdtDef {
1970 // AdtDef are always interned and this is part of TyS equality
1972 fn eq(&self, other: &Self) -> bool { ptr::eq(self, other) }
1975 impl Eq for AdtDef {}
1977 impl Hash for AdtDef {
1979 fn hash<H: Hasher>(&self, s: &mut H) {
1980 (self as *const AdtDef).hash(s)
1984 impl<'tcx> rustc_serialize::UseSpecializedEncodable for &'tcx AdtDef {
1985 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1990 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx AdtDef {}
1993 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
1994 fn hash_stable<W: StableHasherResult>(&self,
1995 hcx: &mut StableHashingContext<'a>,
1996 hasher: &mut StableHasher<W>) {
1998 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default();
2001 let hash: Fingerprint = CACHE.with(|cache| {
2002 let addr = self as *const AdtDef as usize;
2003 *cache.borrow_mut().entry(addr).or_insert_with(|| {
2011 let mut hasher = StableHasher::new();
2012 did.hash_stable(hcx, &mut hasher);
2013 variants.hash_stable(hcx, &mut hasher);
2014 flags.hash_stable(hcx, &mut hasher);
2015 repr.hash_stable(hcx, &mut hasher);
2021 hash.hash_stable(hcx, hasher);
2025 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
2026 pub enum AdtKind { Struct, Union, Enum }
2028 impl Into<DataTypeKind> for AdtKind {
2029 fn into(self) -> DataTypeKind {
2031 AdtKind::Struct => DataTypeKind::Struct,
2032 AdtKind::Union => DataTypeKind::Union,
2033 AdtKind::Enum => DataTypeKind::Enum,
2039 #[derive(RustcEncodable, RustcDecodable, Default)]
2040 pub struct ReprFlags: u8 {
2041 const IS_C = 1 << 0;
2042 const IS_SIMD = 1 << 1;
2043 const IS_TRANSPARENT = 1 << 2;
2044 // Internal only for now. If true, don't reorder fields.
2045 const IS_LINEAR = 1 << 3;
2047 // Any of these flags being set prevent field reordering optimisation.
2048 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
2049 ReprFlags::IS_SIMD.bits |
2050 ReprFlags::IS_LINEAR.bits;
2054 impl_stable_hash_for!(struct ReprFlags {
2058 /// Represents the repr options provided by the user,
2059 #[derive(Copy, Clone, Debug, Eq, PartialEq, RustcEncodable, RustcDecodable, Default)]
2060 pub struct ReprOptions {
2061 pub int: Option<attr::IntType>,
2062 pub align: Option<Align>,
2063 pub pack: Option<Align>,
2064 pub flags: ReprFlags,
2067 impl_stable_hash_for!(struct ReprOptions {
2075 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
2076 let mut flags = ReprFlags::empty();
2077 let mut size = None;
2078 let mut max_align: Option<Align> = None;
2079 let mut min_pack: Option<Align> = None;
2080 for attr in tcx.get_attrs(did).iter() {
2081 for r in attr::find_repr_attrs(&tcx.sess.parse_sess, attr) {
2082 flags.insert(match r {
2083 attr::ReprC => ReprFlags::IS_C,
2084 attr::ReprPacked(pack) => {
2085 let pack = Align::from_bytes(pack as u64).unwrap();
2086 min_pack = Some(if let Some(min_pack) = min_pack {
2093 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2094 attr::ReprSimd => ReprFlags::IS_SIMD,
2095 attr::ReprInt(i) => {
2099 attr::ReprAlign(align) => {
2100 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2107 // This is here instead of layout because the choice must make it into metadata.
2108 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2109 flags.insert(ReprFlags::IS_LINEAR);
2111 ReprOptions { int: size, align: max_align, pack: min_pack, flags: flags }
2115 pub fn simd(&self) -> bool { self.flags.contains(ReprFlags::IS_SIMD) }
2117 pub fn c(&self) -> bool { self.flags.contains(ReprFlags::IS_C) }
2119 pub fn packed(&self) -> bool { self.pack.is_some() }
2121 pub fn transparent(&self) -> bool { self.flags.contains(ReprFlags::IS_TRANSPARENT) }
2123 pub fn linear(&self) -> bool { self.flags.contains(ReprFlags::IS_LINEAR) }
2125 pub fn discr_type(&self) -> attr::IntType {
2126 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2129 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2130 /// layout" optimizations, such as representing `Foo<&T>` as a
2132 pub fn inhibit_enum_layout_opt(&self) -> bool {
2133 self.c() || self.int.is_some()
2136 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2137 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2138 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2139 if let Some(pack) = self.pack {
2140 if pack.bytes() == 1 {
2144 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2147 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2148 pub fn inhibit_union_abi_opt(&self) -> bool {
2154 /// Creates a new `AdtDef`.
2159 variants: IndexVec<VariantIdx, VariantDef>,
2162 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
2163 let mut flags = AdtFlags::NO_ADT_FLAGS;
2165 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
2166 debug!("found non-exhaustive variant list for {:?}", did);
2167 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
2170 flags |= match kind {
2171 AdtKind::Enum => AdtFlags::IS_ENUM,
2172 AdtKind::Union => AdtFlags::IS_UNION,
2173 AdtKind::Struct => AdtFlags::IS_STRUCT,
2176 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
2177 flags |= AdtFlags::HAS_CTOR;
2180 let attrs = tcx.get_attrs(did);
2181 if attr::contains_name(&attrs, sym::fundamental) {
2182 flags |= AdtFlags::IS_FUNDAMENTAL;
2184 if Some(did) == tcx.lang_items().phantom_data() {
2185 flags |= AdtFlags::IS_PHANTOM_DATA;
2187 if Some(did) == tcx.lang_items().owned_box() {
2188 flags |= AdtFlags::IS_BOX;
2190 if Some(did) == tcx.lang_items().arc() {
2191 flags |= AdtFlags::IS_ARC;
2193 if Some(did) == tcx.lang_items().rc() {
2194 flags |= AdtFlags::IS_RC;
2205 /// Returns `true` if this is a struct.
2207 pub fn is_struct(&self) -> bool {
2208 self.flags.contains(AdtFlags::IS_STRUCT)
2211 /// Returns `true` if this is a union.
2213 pub fn is_union(&self) -> bool {
2214 self.flags.contains(AdtFlags::IS_UNION)
2217 /// Returns `true` if this is a enum.
2219 pub fn is_enum(&self) -> bool {
2220 self.flags.contains(AdtFlags::IS_ENUM)
2223 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
2225 pub fn is_variant_list_non_exhaustive(&self) -> bool {
2226 self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
2229 /// Returns the kind of the ADT.
2231 pub fn adt_kind(&self) -> AdtKind {
2234 } else if self.is_union() {
2241 /// Returns a description of this abstract data type.
2242 pub fn descr(&self) -> &'static str {
2243 match self.adt_kind() {
2244 AdtKind::Struct => "struct",
2245 AdtKind::Union => "union",
2246 AdtKind::Enum => "enum",
2250 /// Returns a description of a variant of this abstract data type.
2252 pub fn variant_descr(&self) -> &'static str {
2253 match self.adt_kind() {
2254 AdtKind::Struct => "struct",
2255 AdtKind::Union => "union",
2256 AdtKind::Enum => "variant",
2260 /// If this function returns `true`, it implies that `is_struct` must return `true`.
2262 pub fn has_ctor(&self) -> bool {
2263 self.flags.contains(AdtFlags::HAS_CTOR)
2266 /// Returns `true` if this type is `#[fundamental]` for the purposes
2267 /// of coherence checking.
2269 pub fn is_fundamental(&self) -> bool {
2270 self.flags.contains(AdtFlags::IS_FUNDAMENTAL)
2273 /// Returns `true` if this is `PhantomData<T>`.
2275 pub fn is_phantom_data(&self) -> bool {
2276 self.flags.contains(AdtFlags::IS_PHANTOM_DATA)
2279 /// Returns `true` if this is `Arc<T>`.
2280 pub fn is_arc(&self) -> bool {
2281 self.flags.contains(AdtFlags::IS_ARC)
2284 /// Returns `true` if this is `Rc<T>`.
2285 pub fn is_rc(&self) -> bool {
2286 self.flags.contains(AdtFlags::IS_RC)
2289 /// Returns `true` if this is Box<T>.
2291 pub fn is_box(&self) -> bool {
2292 self.flags.contains(AdtFlags::IS_BOX)
2295 /// Returns `true` if this type has a destructor.
2296 pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
2297 self.destructor(tcx).is_some()
2300 /// Asserts this is a struct or union and returns its unique variant.
2301 pub fn non_enum_variant(&self) -> &VariantDef {
2302 assert!(self.is_struct() || self.is_union());
2303 &self.variants[VariantIdx::new(0)]
2307 pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> &'tcx GenericPredicates<'tcx> {
2308 tcx.predicates_of(self.did)
2311 /// Returns an iterator over all fields contained
2314 pub fn all_fields(&self) -> impl Iterator<Item=&FieldDef> + Clone {
2315 self.variants.iter().flat_map(|v| v.fields.iter())
2318 pub fn is_payloadfree(&self) -> bool {
2319 !self.variants.is_empty() &&
2320 self.variants.iter().all(|v| v.fields.is_empty())
2323 /// Return a `VariantDef` given a variant id.
2324 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
2325 self.variants.iter().find(|v| v.def_id == vid)
2326 .expect("variant_with_id: unknown variant")
2329 /// Return a `VariantDef` given a constructor id.
2330 pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
2331 self.variants.iter().find(|v| v.ctor_def_id == Some(cid))
2332 .expect("variant_with_ctor_id: unknown variant")
2335 /// Return the index of `VariantDef` given a variant id.
2336 pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
2337 self.variants.iter_enumerated().find(|(_, v)| v.def_id == vid)
2338 .expect("variant_index_with_id: unknown variant").0
2341 /// Return the index of `VariantDef` given a constructor id.
2342 pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
2343 self.variants.iter_enumerated().find(|(_, v)| v.ctor_def_id == Some(cid))
2344 .expect("variant_index_with_ctor_id: unknown variant").0
2347 pub fn variant_of_res(&self, res: Res) -> &VariantDef {
2349 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
2350 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
2351 Res::Def(DefKind::Struct, _) | Res::Def(DefKind::Union, _) |
2352 Res::Def(DefKind::TyAlias, _) | Res::Def(DefKind::AssocTy, _) | Res::SelfTy(..) |
2353 Res::SelfCtor(..) => self.non_enum_variant(),
2354 _ => bug!("unexpected res {:?} in variant_of_res", res)
2359 pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
2360 let param_env = tcx.param_env(expr_did);
2361 let repr_type = self.repr.discr_type();
2362 let substs = InternalSubsts::identity_for_item(tcx.global_tcx(), expr_did);
2363 let instance = ty::Instance::new(expr_did, substs);
2364 let cid = GlobalId {
2368 match tcx.const_eval(param_env.and(cid)) {
2370 // FIXME: Find the right type and use it instead of `val.ty` here
2371 if let Some(b) = val.try_eval_bits(tcx.global_tcx(), param_env, val.ty) {
2372 trace!("discriminants: {} ({:?})", b, repr_type);
2378 info!("invalid enum discriminant: {:#?}", val);
2379 crate::mir::interpret::struct_error(
2380 tcx.at(tcx.def_span(expr_did)),
2381 "constant evaluation of enum discriminant resulted in non-integer",
2386 Err(ErrorHandled::Reported) => {
2387 if !expr_did.is_local() {
2388 span_bug!(tcx.def_span(expr_did),
2389 "variant discriminant evaluation succeeded \
2390 in its crate but failed locally");
2394 Err(ErrorHandled::TooGeneric) => span_bug!(
2395 tcx.def_span(expr_did),
2396 "enum discriminant depends on generic arguments",
2402 pub fn discriminants(
2405 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
2406 let repr_type = self.repr.discr_type();
2407 let initial = repr_type.initial_discriminant(tcx.global_tcx());
2408 let mut prev_discr = None::<Discr<'tcx>>;
2409 self.variants.iter_enumerated().map(move |(i, v)| {
2410 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
2411 if let VariantDiscr::Explicit(expr_did) = v.discr {
2412 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
2416 prev_discr = Some(discr);
2423 pub fn variant_range(&self) -> Range<VariantIdx> {
2424 (VariantIdx::new(0)..VariantIdx::new(self.variants.len()))
2427 /// Computes the discriminant value used by a specific variant.
2428 /// Unlike `discriminants`, this is (amortized) constant-time,
2429 /// only doing at most one query for evaluating an explicit
2430 /// discriminant (the last one before the requested variant),
2431 /// assuming there are no constant-evaluation errors there.
2433 pub fn discriminant_for_variant(
2436 variant_index: VariantIdx,
2438 let (val, offset) = self.discriminant_def_for_variant(variant_index);
2439 let explicit_value = val
2440 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
2441 .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx.global_tcx()));
2442 explicit_value.checked_add(tcx, offset as u128).0
2445 /// Yields a `DefId` for the discriminant and an offset to add to it
2446 /// Alternatively, if there is no explicit discriminant, returns the
2447 /// inferred discriminant directly.
2448 pub fn discriminant_def_for_variant(
2450 variant_index: VariantIdx,
2451 ) -> (Option<DefId>, u32) {
2452 let mut explicit_index = variant_index.as_u32();
2455 match self.variants[VariantIdx::from_u32(explicit_index)].discr {
2456 ty::VariantDiscr::Relative(0) => {
2460 ty::VariantDiscr::Relative(distance) => {
2461 explicit_index -= distance;
2463 ty::VariantDiscr::Explicit(did) => {
2464 expr_did = Some(did);
2469 (expr_did, variant_index.as_u32() - explicit_index)
2472 pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
2473 tcx.adt_destructor(self.did)
2476 /// Returns a list of types such that `Self: Sized` if and only
2477 /// if that type is `Sized`, or `TyErr` if this type is recursive.
2479 /// Oddly enough, checking that the sized-constraint is `Sized` is
2480 /// actually more expressive than checking all members:
2481 /// the `Sized` trait is inductive, so an associated type that references
2482 /// `Self` would prevent its containing ADT from being `Sized`.
2484 /// Due to normalization being eager, this applies even if
2485 /// the associated type is behind a pointer (e.g., issue #31299).
2486 pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] {
2487 tcx.adt_sized_constraint(self.did).0
2490 fn sized_constraint_for_ty(&self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Vec<Ty<'tcx>> {
2491 let result = match ty.sty {
2492 Bool | Char | Int(..) | Uint(..) | Float(..) |
2493 RawPtr(..) | Ref(..) | FnDef(..) | FnPtr(_) |
2494 Array(..) | Closure(..) | Generator(..) | Never => {
2503 GeneratorWitness(..) => {
2504 // these are never sized - return the target type
2511 Some(ty) => self.sized_constraint_for_ty(tcx, ty.expect_ty()),
2515 Adt(adt, substs) => {
2517 let adt_tys = adt.sized_constraint(tcx);
2518 debug!("sized_constraint_for_ty({:?}) intermediate = {:?}",
2521 .map(|ty| ty.subst(tcx, substs))
2522 .flat_map(|ty| self.sized_constraint_for_ty(tcx, ty))
2526 Projection(..) | Opaque(..) => {
2527 // must calculate explicitly.
2528 // FIXME: consider special-casing always-Sized projections
2532 UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
2535 // perf hack: if there is a `T: Sized` bound, then
2536 // we know that `T` is Sized and do not need to check
2539 let sized_trait = match tcx.lang_items().sized_trait() {
2541 _ => return vec![ty]
2543 let sized_predicate = Binder::dummy(TraitRef {
2544 def_id: sized_trait,
2545 substs: tcx.mk_substs_trait(ty, &[])
2547 let predicates = &tcx.predicates_of(self.did).predicates;
2548 if predicates.iter().any(|(p, _)| *p == sized_predicate) {
2558 bug!("unexpected type `{:?}` in sized_constraint_for_ty",
2562 debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result);
2567 impl<'tcx> FieldDef {
2568 /// Returns the type of this field. The `subst` is typically obtained
2569 /// via the second field of `TyKind::AdtDef`.
2570 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2571 tcx.type_of(self.did).subst(tcx, subst)
2575 /// Represents the various closure traits in the language. This
2576 /// will determine the type of the environment (`self`, in the
2577 /// desugaring) argument that the closure expects.
2579 /// You can get the environment type of a closure using
2580 /// `tcx.closure_env_ty()`.
2581 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug,
2582 RustcEncodable, RustcDecodable, HashStable)]
2583 pub enum ClosureKind {
2584 // Warning: Ordering is significant here! The ordering is chosen
2585 // because the trait Fn is a subtrait of FnMut and so in turn, and
2586 // hence we order it so that Fn < FnMut < FnOnce.
2592 impl<'tcx> ClosureKind {
2593 // This is the initial value used when doing upvar inference.
2594 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2596 pub fn trait_did(&self, tcx: TyCtxt<'tcx>) -> DefId {
2598 ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem, None),
2599 ClosureKind::FnMut => {
2600 tcx.require_lang_item(FnMutTraitLangItem, None)
2602 ClosureKind::FnOnce => {
2603 tcx.require_lang_item(FnOnceTraitLangItem, None)
2608 /// Returns `true` if this a type that impls this closure kind
2609 /// must also implement `other`.
2610 pub fn extends(self, other: ty::ClosureKind) -> bool {
2611 match (self, other) {
2612 (ClosureKind::Fn, ClosureKind::Fn) => true,
2613 (ClosureKind::Fn, ClosureKind::FnMut) => true,
2614 (ClosureKind::Fn, ClosureKind::FnOnce) => true,
2615 (ClosureKind::FnMut, ClosureKind::FnMut) => true,
2616 (ClosureKind::FnMut, ClosureKind::FnOnce) => true,
2617 (ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
2622 /// Returns the representative scalar type for this closure kind.
2623 /// See `TyS::to_opt_closure_kind` for more details.
2624 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2626 ty::ClosureKind::Fn => tcx.types.i8,
2627 ty::ClosureKind::FnMut => tcx.types.i16,
2628 ty::ClosureKind::FnOnce => tcx.types.i32,
2633 impl<'tcx> TyS<'tcx> {
2634 /// Iterator that walks `self` and any types reachable from
2635 /// `self`, in depth-first order. Note that just walks the types
2636 /// that appear in `self`, it does not descend into the fields of
2637 /// structs or variants. For example:
2640 /// isize => { isize }
2641 /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
2642 /// [isize] => { [isize], isize }
2644 pub fn walk(&'tcx self) -> TypeWalker<'tcx> {
2645 TypeWalker::new(self)
2648 /// Iterator that walks the immediate children of `self`. Hence
2649 /// `Foo<Bar<i32>, u32>` yields the sequence `[Bar<i32>, u32]`
2650 /// (but not `i32`, like `walk`).
2651 pub fn walk_shallow(&'tcx self) -> smallvec::IntoIter<walk::TypeWalkerArray<'tcx>> {
2652 walk::walk_shallow(self)
2655 /// Walks `ty` and any types appearing within `ty`, invoking the
2656 /// callback `f` on each type. If the callback returns `false`, then the
2657 /// children of the current type are ignored.
2659 /// Note: prefer `ty.walk()` where possible.
2660 pub fn maybe_walk<F>(&'tcx self, mut f: F)
2661 where F: FnMut(Ty<'tcx>) -> bool
2663 let mut walker = self.walk();
2664 while let Some(ty) = walker.next() {
2666 walker.skip_current_subtree();
2673 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2675 hir::MutMutable => MutBorrow,
2676 hir::MutImmutable => ImmBorrow,
2680 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2681 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2682 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2684 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2686 MutBorrow => hir::MutMutable,
2687 ImmBorrow => hir::MutImmutable,
2689 // We have no type corresponding to a unique imm borrow, so
2690 // use `&mut`. It gives all the capabilities of an `&uniq`
2691 // and hence is a safe "over approximation".
2692 UniqueImmBorrow => hir::MutMutable,
2696 pub fn to_user_str(&self) -> &'static str {
2698 MutBorrow => "mutable",
2699 ImmBorrow => "immutable",
2700 UniqueImmBorrow => "uniquely immutable",
2705 #[derive(Debug, Clone)]
2706 pub enum Attributes<'tcx> {
2707 Owned(Lrc<[ast::Attribute]>),
2708 Borrowed(&'tcx [ast::Attribute]),
2711 impl<'tcx> ::std::ops::Deref for Attributes<'tcx> {
2712 type Target = [ast::Attribute];
2714 fn deref(&self) -> &[ast::Attribute] {
2716 &Attributes::Owned(ref data) => &data,
2717 &Attributes::Borrowed(data) => data
2722 #[derive(Debug, PartialEq, Eq)]
2723 pub enum ImplOverlapKind {
2724 /// These impls are always allowed to overlap.
2726 /// These impls are allowed to overlap, but that raises
2727 /// an issue #33140 future-compatibility warning.
2729 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2730 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2732 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2733 /// that difference, making what reduces to the following set of impls:
2737 /// impl Trait for dyn Send + Sync {}
2738 /// impl Trait for dyn Sync + Send {}
2741 /// Obviously, once we made these types be identical, that code causes a coherence
2742 /// error and a fairly big headache for us. However, luckily for us, the trait
2743 /// `Trait` used in this case is basically a marker trait, and therefore having
2744 /// overlapping impls for it is sound.
2746 /// To handle this, we basically regard the trait as a marker trait, with an additional
2747 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2748 /// it has the following restrictions:
2750 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2752 /// 2. The trait-ref of both impls must be equal.
2753 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2755 /// 4. Neither of the impls can have any where-clauses.
2757 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2761 impl<'tcx> TyCtxt<'tcx> {
2762 pub fn body_tables(self, body: hir::BodyId) -> &'tcx TypeckTables<'tcx> {
2763 self.typeck_tables_of(self.hir().body_owner_def_id(body))
2766 /// Returns an iterator of the `DefId`s for all body-owners in this
2767 /// crate. If you would prefer to iterate over the bodies
2768 /// themselves, you can do `self.hir().krate().body_ids.iter()`.
2769 pub fn body_owners(self) -> impl Iterator<Item = DefId> + Captures<'tcx> + 'tcx {
2773 .map(move |&body_id| self.hir().body_owner_def_id(body_id))
2776 pub fn par_body_owners<F: Fn(DefId) + sync::Sync + sync::Send>(self, f: F) {
2777 par_iter(&self.hir().krate().body_ids).for_each(|&body_id| {
2778 f(self.hir().body_owner_def_id(body_id))
2782 pub fn provided_trait_methods(self, id: DefId) -> Vec<AssocItem> {
2783 self.associated_items(id)
2784 .filter(|item| item.kind == AssocKind::Method && item.defaultness.has_value())
2788 pub fn trait_relevant_for_never(self, did: DefId) -> bool {
2789 self.associated_items(did).any(|item| {
2790 item.relevant_for_never()
2794 pub fn opt_associated_item(self, def_id: DefId) -> Option<AssocItem> {
2795 let is_associated_item = if let Some(hir_id) = self.hir().as_local_hir_id(def_id) {
2796 match self.hir().get(hir_id) {
2797 Node::TraitItem(_) | Node::ImplItem(_) => true,
2801 match self.def_kind(def_id).expect("no def for `DefId`") {
2804 | DefKind::AssocTy => true,
2809 if is_associated_item {
2810 Some(self.associated_item(def_id))
2816 fn associated_item_from_trait_item_ref(self,
2817 parent_def_id: DefId,
2818 parent_vis: &hir::Visibility,
2819 trait_item_ref: &hir::TraitItemRef)
2821 let def_id = self.hir().local_def_id(trait_item_ref.id.hir_id);
2822 let (kind, has_self) = match trait_item_ref.kind {
2823 hir::AssocItemKind::Const => (ty::AssocKind::Const, false),
2824 hir::AssocItemKind::Method { has_self } => {
2825 (ty::AssocKind::Method, has_self)
2827 hir::AssocItemKind::Type => (ty::AssocKind::Type, false),
2828 hir::AssocItemKind::OpaqueTy => bug!("only impls can have opaque types"),
2832 ident: trait_item_ref.ident,
2834 // Visibility of trait items is inherited from their traits.
2835 vis: Visibility::from_hir(parent_vis, trait_item_ref.id.hir_id, self),
2836 defaultness: trait_item_ref.defaultness,
2838 container: TraitContainer(parent_def_id),
2839 method_has_self_argument: has_self
2843 fn associated_item_from_impl_item_ref(self,
2844 parent_def_id: DefId,
2845 impl_item_ref: &hir::ImplItemRef)
2847 let def_id = self.hir().local_def_id(impl_item_ref.id.hir_id);
2848 let (kind, has_self) = match impl_item_ref.kind {
2849 hir::AssocItemKind::Const => (ty::AssocKind::Const, false),
2850 hir::AssocItemKind::Method { has_self } => {
2851 (ty::AssocKind::Method, has_self)
2853 hir::AssocItemKind::Type => (ty::AssocKind::Type, false),
2854 hir::AssocItemKind::OpaqueTy => (ty::AssocKind::OpaqueTy, false),
2858 ident: impl_item_ref.ident,
2860 // Visibility of trait impl items doesn't matter.
2861 vis: ty::Visibility::from_hir(&impl_item_ref.vis, impl_item_ref.id.hir_id, self),
2862 defaultness: impl_item_ref.defaultness,
2864 container: ImplContainer(parent_def_id),
2865 method_has_self_argument: has_self
2869 pub fn field_index(self, hir_id: hir::HirId, tables: &TypeckTables<'_>) -> usize {
2870 tables.field_indices().get(hir_id).cloned().expect("no index for a field")
2873 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2874 variant.fields.iter().position(|field| {
2875 self.hygienic_eq(ident, field.ident, variant.def_id)
2879 pub fn associated_items(self, def_id: DefId) -> AssocItemsIterator<'tcx> {
2880 // Ideally, we would use `-> impl Iterator` here, but it falls
2881 // afoul of the conservative "capture [restrictions]" we put
2882 // in place, so we use a hand-written iterator.
2884 // [restrictions]: https://github.com/rust-lang/rust/issues/34511#issuecomment-373423999
2885 AssocItemsIterator {
2887 def_ids: self.associated_item_def_ids(def_id),
2892 /// Returns `true` if the impls are the same polarity and the trait either
2893 /// has no items or is annotated #[marker] and prevents item overrides.
2894 pub fn impls_are_allowed_to_overlap(self, def_id1: DefId, def_id2: DefId)
2895 -> Option<ImplOverlapKind>
2897 let is_legit = if self.features().overlapping_marker_traits {
2898 let trait1_is_empty = self.impl_trait_ref(def_id1)
2899 .map_or(false, |trait_ref| {
2900 self.associated_item_def_ids(trait_ref.def_id).is_empty()
2902 let trait2_is_empty = self.impl_trait_ref(def_id2)
2903 .map_or(false, |trait_ref| {
2904 self.associated_item_def_ids(trait_ref.def_id).is_empty()
2906 self.impl_polarity(def_id1) == self.impl_polarity(def_id2)
2910 let is_marker_impl = |def_id: DefId| -> bool {
2911 let trait_ref = self.impl_trait_ref(def_id);
2912 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2914 self.impl_polarity(def_id1) == self.impl_polarity(def_id2)
2915 && is_marker_impl(def_id1)
2916 && is_marker_impl(def_id2)
2920 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted)",
2922 Some(ImplOverlapKind::Permitted)
2924 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2925 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2926 if self_ty1 == self_ty2 {
2927 debug!("impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2929 return Some(ImplOverlapKind::Issue33140);
2931 debug!("impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2932 def_id1, def_id2, self_ty1, self_ty2);
2937 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None",
2943 /// Returns `ty::VariantDef` if `res` refers to a struct,
2944 /// or variant or their constructors, panics otherwise.
2945 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2947 Res::Def(DefKind::Variant, did) => {
2948 let enum_did = self.parent(did).unwrap();
2949 self.adt_def(enum_did).variant_with_id(did)
2951 Res::Def(DefKind::Struct, did) | Res::Def(DefKind::Union, did) => {
2952 self.adt_def(did).non_enum_variant()
2954 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2955 let variant_did = self.parent(variant_ctor_did).unwrap();
2956 let enum_did = self.parent(variant_did).unwrap();
2957 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2959 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2960 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2961 self.adt_def(struct_did).non_enum_variant()
2963 _ => bug!("expect_variant_res used with unexpected res {:?}", res)
2967 pub fn item_name(self, id: DefId) -> Symbol {
2968 if id.index == CRATE_DEF_INDEX {
2969 self.original_crate_name(id.krate)
2971 let def_key = self.def_key(id);
2972 match def_key.disambiguated_data.data {
2973 // The name of a constructor is that of its parent.
2974 hir_map::DefPathData::Ctor =>
2975 self.item_name(DefId {
2977 index: def_key.parent.unwrap()
2979 _ => def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
2980 bug!("item_name: no name for {:?}", self.def_path(id));
2986 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2987 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2989 ty::InstanceDef::Item(did) => {
2990 self.optimized_mir(did)
2992 ty::InstanceDef::VtableShim(..) |
2993 ty::InstanceDef::Intrinsic(..) |
2994 ty::InstanceDef::FnPtrShim(..) |
2995 ty::InstanceDef::Virtual(..) |
2996 ty::InstanceDef::ClosureOnceShim { .. } |
2997 ty::InstanceDef::DropGlue(..) |
2998 ty::InstanceDef::CloneShim(..) => {
2999 self.mir_shims(instance)
3004 /// Gets the attributes of a definition.
3005 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
3006 if let Some(id) = self.hir().as_local_hir_id(did) {
3007 Attributes::Borrowed(self.hir().attrs(id))
3009 Attributes::Owned(self.item_attrs(did))
3013 /// Determines whether an item is annotated with an attribute.
3014 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
3015 attr::contains_name(&self.get_attrs(did), attr)
3018 /// Returns `true` if this is an `auto trait`.
3019 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
3020 self.trait_def(trait_def_id).has_auto_impl
3023 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
3024 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
3027 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
3028 /// If it implements no trait, returns `None`.
3029 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
3030 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
3033 /// If the given defid describes a method belonging to an impl, returns the
3034 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
3035 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
3036 let item = if def_id.krate != LOCAL_CRATE {
3037 if let Some(DefKind::Method) = self.def_kind(def_id) {
3038 Some(self.associated_item(def_id))
3043 self.opt_associated_item(def_id)
3046 item.and_then(|trait_item|
3047 match trait_item.container {
3048 TraitContainer(_) => None,
3049 ImplContainer(def_id) => Some(def_id),
3054 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
3055 /// with the name of the crate containing the impl.
3056 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
3057 if impl_did.is_local() {
3058 let hir_id = self.hir().as_local_hir_id(impl_did).unwrap();
3059 Ok(self.hir().span(hir_id))
3061 Err(self.crate_name(impl_did.krate))
3065 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
3066 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
3067 /// definition's parent/scope to perform comparison.
3068 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
3069 // We could use `Ident::eq` here, but we deliberately don't. The name
3070 // comparison fails frequently, and we want to avoid the expensive
3071 // `modern()` calls required for the span comparison whenever possible.
3072 use_name.name == def_name.name &&
3073 use_name.span.ctxt().hygienic_eq(def_name.span.ctxt(),
3074 self.expansion_that_defined(def_parent_def_id))
3077 fn expansion_that_defined(self, scope: DefId) -> ExpnId {
3079 LOCAL_CRATE => self.hir().definitions().expansion_that_defined(scope.index),
3080 _ => ExpnId::root(),
3084 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
3085 ident.span.modernize_and_adjust(self.expansion_that_defined(scope));
3089 pub fn adjust_ident_and_get_scope(self, mut ident: Ident, scope: DefId, block: hir::HirId)
3091 let scope = match ident.span.modernize_and_adjust(self.expansion_that_defined(scope)) {
3092 Some(actual_expansion) =>
3093 self.hir().definitions().parent_module_of_macro_def(actual_expansion),
3094 None => self.hir().get_module_parent(block),
3100 pub struct AssocItemsIterator<'tcx> {
3102 def_ids: &'tcx [DefId],
3106 impl Iterator for AssocItemsIterator<'_> {
3107 type Item = AssocItem;
3109 fn next(&mut self) -> Option<AssocItem> {
3110 let def_id = self.def_ids.get(self.next_index)?;
3111 self.next_index += 1;
3112 Some(self.tcx.associated_item(*def_id))
3116 fn associated_item(tcx: TyCtxt<'_>, def_id: DefId) -> AssocItem {
3117 let id = tcx.hir().as_local_hir_id(def_id).unwrap();
3118 let parent_id = tcx.hir().get_parent_item(id);
3119 let parent_def_id = tcx.hir().local_def_id(parent_id);
3120 let parent_item = tcx.hir().expect_item(parent_id);
3121 match parent_item.node {
3122 hir::ItemKind::Impl(.., ref impl_item_refs) => {
3123 if let Some(impl_item_ref) = impl_item_refs.iter().find(|i| i.id.hir_id == id) {
3124 let assoc_item = tcx.associated_item_from_impl_item_ref(parent_def_id,
3126 debug_assert_eq!(assoc_item.def_id, def_id);
3131 hir::ItemKind::Trait(.., ref trait_item_refs) => {
3132 if let Some(trait_item_ref) = trait_item_refs.iter().find(|i| i.id.hir_id == id) {
3133 let assoc_item = tcx.associated_item_from_trait_item_ref(parent_def_id,
3136 debug_assert_eq!(assoc_item.def_id, def_id);
3144 span_bug!(parent_item.span,
3145 "unexpected parent of trait or impl item or item not found: {:?}",
3149 #[derive(Clone, HashStable)]
3150 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
3152 /// Calculates the `Sized` constraint.
3154 /// In fact, there are only a few options for the types in the constraint:
3155 /// - an obviously-unsized type
3156 /// - a type parameter or projection whose Sizedness can't be known
3157 /// - a tuple of type parameters or projections, if there are multiple
3159 /// - a Error, if a type contained itself. The representability
3160 /// check should catch this case.
3161 fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> AdtSizedConstraint<'_> {
3162 let def = tcx.adt_def(def_id);
3164 let result = tcx.mk_type_list(def.variants.iter().flat_map(|v| {
3167 def.sized_constraint_for_ty(tcx, tcx.type_of(f.did))
3170 debug!("adt_sized_constraint: {:?} => {:?}", def, result);
3172 AdtSizedConstraint(result)
3175 fn associated_item_def_ids(tcx: TyCtxt<'_>, def_id: DefId) -> &[DefId] {
3176 let id = tcx.hir().as_local_hir_id(def_id).unwrap();
3177 let item = tcx.hir().expect_item(id);
3179 hir::ItemKind::Trait(.., ref trait_item_refs) => {
3180 tcx.arena.alloc_from_iter(
3181 trait_item_refs.iter()
3182 .map(|trait_item_ref| trait_item_ref.id)
3183 .map(|id| tcx.hir().local_def_id(id.hir_id))
3186 hir::ItemKind::Impl(.., ref impl_item_refs) => {
3187 tcx.arena.alloc_from_iter(
3188 impl_item_refs.iter()
3189 .map(|impl_item_ref| impl_item_ref.id)
3190 .map(|id| tcx.hir().local_def_id(id.hir_id))
3193 hir::ItemKind::TraitAlias(..) => &[],
3194 _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait")
3198 fn def_span(tcx: TyCtxt<'_>, def_id: DefId) -> Span {
3199 tcx.hir().span_if_local(def_id).unwrap()
3202 /// If the given `DefId` describes an item belonging to a trait,
3203 /// returns the `DefId` of the trait that the trait item belongs to;
3204 /// otherwise, returns `None`.
3205 fn trait_of_item(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
3206 tcx.opt_associated_item(def_id)
3207 .and_then(|associated_item| {
3208 match associated_item.container {
3209 TraitContainer(def_id) => Some(def_id),
3210 ImplContainer(_) => None
3215 /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition.
3216 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
3217 if let Some(hir_id) = tcx.hir().as_local_hir_id(def_id) {
3218 if let Node::Item(item) = tcx.hir().get(hir_id) {
3219 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.node {
3220 return opaque_ty.impl_trait_fn;
3227 /// See `ParamEnv` struct definition for details.
3228 fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ParamEnv<'_> {
3229 // The param_env of an impl Trait type is its defining function's param_env
3230 if let Some(parent) = is_impl_trait_defn(tcx, def_id) {
3231 return param_env(tcx, parent);
3233 // Compute the bounds on Self and the type parameters.
3235 let InstantiatedPredicates { predicates } =
3236 tcx.predicates_of(def_id).instantiate_identity(tcx);
3238 // Finally, we have to normalize the bounds in the environment, in
3239 // case they contain any associated type projections. This process
3240 // can yield errors if the put in illegal associated types, like
3241 // `<i32 as Foo>::Bar` where `i32` does not implement `Foo`. We
3242 // report these errors right here; this doesn't actually feel
3243 // right to me, because constructing the environment feels like a
3244 // kind of a "idempotent" action, but I'm not sure where would be
3245 // a better place. In practice, we construct environments for
3246 // every fn once during type checking, and we'll abort if there
3247 // are any errors at that point, so after type checking you can be
3248 // sure that this will succeed without errors anyway.
3250 let unnormalized_env = ty::ParamEnv::new(
3251 tcx.intern_predicates(&predicates),
3252 traits::Reveal::UserFacing,
3253 if tcx.sess.opts.debugging_opts.chalk { Some(def_id) } else { None }
3256 let body_id = tcx.hir().as_local_hir_id(def_id).map_or(hir::DUMMY_HIR_ID, |id| {
3257 tcx.hir().maybe_body_owned_by(id).map_or(id, |body| body.hir_id)
3259 let cause = traits::ObligationCause::misc(tcx.def_span(def_id), body_id);
3260 traits::normalize_param_env_or_error(tcx, def_id, unnormalized_env, cause)
3263 fn crate_disambiguator(tcx: TyCtxt<'_>, crate_num: CrateNum) -> CrateDisambiguator {
3264 assert_eq!(crate_num, LOCAL_CRATE);
3265 tcx.sess.local_crate_disambiguator()
3268 fn original_crate_name(tcx: TyCtxt<'_>, crate_num: CrateNum) -> Symbol {
3269 assert_eq!(crate_num, LOCAL_CRATE);
3270 tcx.crate_name.clone()
3273 fn crate_hash(tcx: TyCtxt<'_>, crate_num: CrateNum) -> Svh {
3274 assert_eq!(crate_num, LOCAL_CRATE);
3275 tcx.hir().crate_hash
3278 fn instance_def_size_estimate<'tcx>(tcx: TyCtxt<'tcx>, instance_def: InstanceDef<'tcx>) -> usize {
3279 match instance_def {
3280 InstanceDef::Item(..) |
3281 InstanceDef::DropGlue(..) => {
3282 let mir = tcx.instance_mir(instance_def);
3283 mir.basic_blocks().iter().map(|bb| bb.statements.len()).sum()
3285 // Estimate the size of other compiler-generated shims to be 1.
3290 /// If `def_id` is an issue 33140 hack impl, returns its self type; otherwise, returns `None`.
3292 /// See [`ImplOverlapKind::Issue33140`] for more details.
3293 fn issue33140_self_ty(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Ty<'_>> {
3294 debug!("issue33140_self_ty({:?})", def_id);
3296 let trait_ref = tcx.impl_trait_ref(def_id).unwrap_or_else(|| {
3297 bug!("issue33140_self_ty called on inherent impl {:?}", def_id)
3300 debug!("issue33140_self_ty({:?}), trait-ref={:?}", def_id, trait_ref);
3302 let is_marker_like =
3303 tcx.impl_polarity(def_id) == hir::ImplPolarity::Positive &&
3304 tcx.associated_item_def_ids(trait_ref.def_id).is_empty();
3306 // Check whether these impls would be ok for a marker trait.
3307 if !is_marker_like {
3308 debug!("issue33140_self_ty - not marker-like!");
3312 // impl must be `impl Trait for dyn Marker1 + Marker2 + ...`
3313 if trait_ref.substs.len() != 1 {
3314 debug!("issue33140_self_ty - impl has substs!");
3318 let predicates = tcx.predicates_of(def_id);
3319 if predicates.parent.is_some() || !predicates.predicates.is_empty() {
3320 debug!("issue33140_self_ty - impl has predicates {:?}!", predicates);
3324 let self_ty = trait_ref.self_ty();
3325 let self_ty_matches = match self_ty.sty {
3326 ty::Dynamic(ref data, ty::ReStatic) => data.principal().is_none(),
3330 if self_ty_matches {
3331 debug!("issue33140_self_ty - MATCHES!");
3334 debug!("issue33140_self_ty - non-matching self type");
3339 pub fn provide(providers: &mut ty::query::Providers<'_>) {
3340 context::provide(providers);
3341 erase_regions::provide(providers);
3342 layout::provide(providers);
3343 util::provide(providers);
3344 constness::provide(providers);
3345 *providers = ty::query::Providers {
3347 associated_item_def_ids,
3348 adt_sized_constraint,
3352 crate_disambiguator,
3353 original_crate_name,
3355 trait_impls_of: trait_def::trait_impls_of_provider,
3356 instance_def_size_estimate,
3362 /// A map for the local crate mapping each type to a vector of its
3363 /// inherent impls. This is not meant to be used outside of coherence;
3364 /// rather, you should request the vector for a specific type via
3365 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
3366 /// (constructing this map requires touching the entire crate).
3367 #[derive(Clone, Debug, Default, HashStable)]
3368 pub struct CrateInherentImpls {
3369 pub inherent_impls: DefIdMap<Vec<DefId>>,
3372 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable)]
3373 pub struct SymbolName {
3374 // FIXME: we don't rely on interning or equality here - better have
3375 // this be a `&'tcx str`.
3376 pub name: InternedString
3379 impl_stable_hash_for!(struct self::SymbolName {
3384 pub fn new(name: &str) -> SymbolName {
3386 name: InternedString::intern(name)
3391 impl fmt::Display for SymbolName {
3392 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3393 fmt::Display::fmt(&self.name, fmt)
3397 impl fmt::Debug for SymbolName {
3398 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3399 fmt::Display::fmt(&self.name, fmt)