1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! misc. type-system utilities too small to deserve their own file
14 use hir::def_id::DefId;
15 use hir::map::{DefPathData, Node};
17 use ich::NodeIdHashingMode;
18 use middle::const_val::ConstVal;
19 use traits::{self, Reveal};
20 use ty::{self, Ty, TyCtxt, TypeFoldable};
21 use ty::fold::TypeVisitor;
22 use ty::subst::{Subst, UnpackedKind};
23 use ty::TypeVariants::*;
24 use util::common::ErrorReported;
25 use middle::lang_items;
27 use rustc_const_math::{ConstInt, ConstIsize, ConstUsize};
28 use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
30 use rustc_data_structures::fx::FxHashMap;
34 use syntax::ast::{self, Name};
35 use syntax::attr::{self, SignedInt, UnsignedInt};
36 use syntax_pos::{Span, DUMMY_SP};
40 pub trait IntTypeExt {
41 fn to_ty<'a, 'gcx, 'tcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx>;
42 fn disr_incr<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, val: Option<Disr>)
44 fn assert_ty_matches(&self, val: Disr);
45 fn initial_discriminant<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Disr;
49 macro_rules! typed_literal {
50 ($tcx:expr, $ty:expr, $lit:expr) => {
52 SignedInt(ast::IntTy::I8) => ConstInt::I8($lit),
53 SignedInt(ast::IntTy::I16) => ConstInt::I16($lit),
54 SignedInt(ast::IntTy::I32) => ConstInt::I32($lit),
55 SignedInt(ast::IntTy::I64) => ConstInt::I64($lit),
56 SignedInt(ast::IntTy::I128) => ConstInt::I128($lit),
57 SignedInt(ast::IntTy::Isize) => match $tcx.sess.target.isize_ty {
58 ast::IntTy::I16 => ConstInt::Isize(ConstIsize::Is16($lit)),
59 ast::IntTy::I32 => ConstInt::Isize(ConstIsize::Is32($lit)),
60 ast::IntTy::I64 => ConstInt::Isize(ConstIsize::Is64($lit)),
63 UnsignedInt(ast::UintTy::U8) => ConstInt::U8($lit),
64 UnsignedInt(ast::UintTy::U16) => ConstInt::U16($lit),
65 UnsignedInt(ast::UintTy::U32) => ConstInt::U32($lit),
66 UnsignedInt(ast::UintTy::U64) => ConstInt::U64($lit),
67 UnsignedInt(ast::UintTy::U128) => ConstInt::U128($lit),
68 UnsignedInt(ast::UintTy::Usize) => match $tcx.sess.target.usize_ty {
69 ast::UintTy::U16 => ConstInt::Usize(ConstUsize::Us16($lit)),
70 ast::UintTy::U32 => ConstInt::Usize(ConstUsize::Us32($lit)),
71 ast::UintTy::U64 => ConstInt::Usize(ConstUsize::Us64($lit)),
78 impl IntTypeExt for attr::IntType {
79 fn to_ty<'a, 'gcx, 'tcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
81 SignedInt(ast::IntTy::I8) => tcx.types.i8,
82 SignedInt(ast::IntTy::I16) => tcx.types.i16,
83 SignedInt(ast::IntTy::I32) => tcx.types.i32,
84 SignedInt(ast::IntTy::I64) => tcx.types.i64,
85 SignedInt(ast::IntTy::I128) => tcx.types.i128,
86 SignedInt(ast::IntTy::Isize) => tcx.types.isize,
87 UnsignedInt(ast::UintTy::U8) => tcx.types.u8,
88 UnsignedInt(ast::UintTy::U16) => tcx.types.u16,
89 UnsignedInt(ast::UintTy::U32) => tcx.types.u32,
90 UnsignedInt(ast::UintTy::U64) => tcx.types.u64,
91 UnsignedInt(ast::UintTy::U128) => tcx.types.u128,
92 UnsignedInt(ast::UintTy::Usize) => tcx.types.usize,
96 fn initial_discriminant<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Disr {
97 typed_literal!(tcx, *self, 0)
100 fn assert_ty_matches(&self, val: Disr) {
102 (SignedInt(ast::IntTy::I8), ConstInt::I8(_)) => {},
103 (SignedInt(ast::IntTy::I16), ConstInt::I16(_)) => {},
104 (SignedInt(ast::IntTy::I32), ConstInt::I32(_)) => {},
105 (SignedInt(ast::IntTy::I64), ConstInt::I64(_)) => {},
106 (SignedInt(ast::IntTy::I128), ConstInt::I128(_)) => {},
107 (SignedInt(ast::IntTy::Isize), ConstInt::Isize(_)) => {},
108 (UnsignedInt(ast::UintTy::U8), ConstInt::U8(_)) => {},
109 (UnsignedInt(ast::UintTy::U16), ConstInt::U16(_)) => {},
110 (UnsignedInt(ast::UintTy::U32), ConstInt::U32(_)) => {},
111 (UnsignedInt(ast::UintTy::U64), ConstInt::U64(_)) => {},
112 (UnsignedInt(ast::UintTy::U128), ConstInt::U128(_)) => {},
113 (UnsignedInt(ast::UintTy::Usize), ConstInt::Usize(_)) => {},
114 _ => bug!("disr type mismatch: {:?} vs {:?}", self, val),
118 fn disr_incr<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, val: Option<Disr>)
120 if let Some(val) = val {
121 self.assert_ty_matches(val);
122 (val + typed_literal!(tcx, *self, 1)).ok()
124 Some(self.initial_discriminant(tcx))
130 #[derive(Copy, Clone)]
131 pub enum CopyImplementationError<'tcx> {
132 InfrigingField(&'tcx ty::FieldDef),
137 /// Describes whether a type is representable. For types that are not
138 /// representable, 'SelfRecursive' and 'ContainsRecursive' are used to
139 /// distinguish between types that are recursive with themselves and types that
140 /// contain a different recursive type. These cases can therefore be treated
141 /// differently when reporting errors.
143 /// The ordering of the cases is significant. They are sorted so that cmp::max
144 /// will keep the "more erroneous" of two values.
145 #[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
146 pub enum Representability {
149 SelfRecursive(Vec<Span>),
152 impl<'tcx> ty::ParamEnv<'tcx> {
153 /// Construct a trait environment suitable for contexts where
154 /// there are no where clauses in scope.
155 pub fn empty(reveal: Reveal) -> Self {
156 Self::new(ty::Slice::empty(), reveal, ty::UniverseIndex::ROOT)
159 /// Construct a trait environment with the given set of predicates.
160 pub fn new(caller_bounds: &'tcx ty::Slice<ty::Predicate<'tcx>>,
162 universe: ty::UniverseIndex)
164 ty::ParamEnv { caller_bounds, reveal, universe }
167 /// Returns a new parameter environment with the same clauses, but
168 /// which "reveals" the true results of projections in all cases
169 /// (even for associated types that are specializable). This is
170 /// the desired behavior during trans and certain other special
171 /// contexts; normally though we want to use `Reveal::UserFacing`,
172 /// which is the default.
173 pub fn reveal_all(self) -> Self {
174 ty::ParamEnv { reveal: Reveal::All, ..self }
177 pub fn can_type_implement_copy<'a>(self,
178 tcx: TyCtxt<'a, 'tcx, 'tcx>,
179 self_type: Ty<'tcx>, span: Span)
180 -> Result<(), CopyImplementationError<'tcx>> {
181 // FIXME: (@jroesch) float this code up
182 tcx.infer_ctxt().enter(|infcx| {
183 let (adt, substs) = match self_type.sty {
184 ty::TyAdt(adt, substs) => (adt, substs),
185 _ => return Err(CopyImplementationError::NotAnAdt),
188 let field_implements_copy = |field: &ty::FieldDef| {
189 let cause = traits::ObligationCause::dummy();
190 match traits::fully_normalize(&infcx, cause, self, &field.ty(tcx, substs)) {
191 Ok(ty) => !infcx.type_moves_by_default(self, ty, span),
196 for variant in &adt.variants {
197 for field in &variant.fields {
198 if !field_implements_copy(field) {
199 return Err(CopyImplementationError::InfrigingField(field));
204 if adt.has_dtor(tcx) {
205 return Err(CopyImplementationError::HasDestructor);
213 impl<'a, 'tcx> TyCtxt<'a, 'tcx, 'tcx> {
214 /// Creates a hash of the type `Ty` which will be the same no matter what crate
215 /// context it's calculated within. This is used by the `type_id` intrinsic.
216 pub fn type_id_hash(self, ty: Ty<'tcx>) -> u64 {
217 let mut hasher = StableHasher::new();
218 let mut hcx = self.create_stable_hashing_context();
220 // We want the type_id be independent of the types free regions, so we
221 // erase them. The erase_regions() call will also anonymize bound
222 // regions, which is desirable too.
223 let ty = self.erase_regions(&ty);
225 hcx.while_hashing_spans(false, |hcx| {
226 hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
227 ty.hash_stable(hcx, &mut hasher);
234 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
235 pub fn has_error_field(self, ty: Ty<'tcx>) -> bool {
237 ty::TyAdt(def, substs) => {
238 for field in def.all_fields() {
239 let field_ty = field.ty(self, substs);
240 if let TyError = field_ty.sty {
250 /// Returns the type of element at index `i` in tuple or tuple-like type `t`.
251 /// For an enum `t`, `variant` is None only if `t` is a univariant enum.
252 pub fn positional_element_ty(self,
255 variant: Option<DefId>) -> Option<Ty<'tcx>> {
256 match (&ty.sty, variant) {
257 (&TyAdt(adt, substs), Some(vid)) => {
258 adt.variant_with_id(vid).fields.get(i).map(|f| f.ty(self, substs))
260 (&TyAdt(adt, substs), None) => {
261 // Don't use `non_enum_variant`, this may be a univariant enum.
262 adt.variants[0].fields.get(i).map(|f| f.ty(self, substs))
264 (&TyTuple(ref v, _), None) => v.get(i).cloned(),
269 /// Returns the type of element at field `n` in struct or struct-like type `t`.
270 /// For an enum `t`, `variant` must be some def id.
271 pub fn named_element_ty(self,
274 variant: Option<DefId>) -> Option<Ty<'tcx>> {
275 match (&ty.sty, variant) {
276 (&TyAdt(adt, substs), Some(vid)) => {
277 adt.variant_with_id(vid).find_field_named(n).map(|f| f.ty(self, substs))
279 (&TyAdt(adt, substs), None) => {
280 adt.non_enum_variant().find_field_named(n).map(|f| f.ty(self, substs))
286 /// Returns the deeply last field of nested structures, or the same type,
287 /// if not a structure at all. Corresponds to the only possible unsized
288 /// field, and its type can be used to determine unsizing strategy.
289 pub fn struct_tail(self, mut ty: Ty<'tcx>) -> Ty<'tcx> {
292 ty::TyAdt(def, substs) => {
293 if !def.is_struct() {
296 match def.non_enum_variant().fields.last() {
297 Some(f) => ty = f.ty(self, substs),
302 ty::TyTuple(tys, _) => {
303 if let Some((&last_ty, _)) = tys.split_last() {
318 /// Same as applying struct_tail on `source` and `target`, but only
319 /// keeps going as long as the two types are instances of the same
320 /// structure definitions.
321 /// For `(Foo<Foo<T>>, Foo<Trait>)`, the result will be `(Foo<T>, Trait)`,
322 /// whereas struct_tail produces `T`, and `Trait`, respectively.
323 pub fn struct_lockstep_tails(self,
326 -> (Ty<'tcx>, Ty<'tcx>) {
327 let (mut a, mut b) = (source, target);
329 match (&a.sty, &b.sty) {
330 (&TyAdt(a_def, a_substs), &TyAdt(b_def, b_substs))
331 if a_def == b_def && a_def.is_struct() => {
332 if let Some(f) = a_def.non_enum_variant().fields.last() {
333 a = f.ty(self, a_substs);
334 b = f.ty(self, b_substs);
339 (&TyTuple(a_tys, _), &TyTuple(b_tys, _))
340 if a_tys.len() == b_tys.len() => {
341 if let Some(a_last) = a_tys.last() {
343 b = b_tys.last().unwrap();
354 /// Given a set of predicates that apply to an object type, returns
355 /// the region bounds that the (erased) `Self` type must
356 /// outlive. Precisely *because* the `Self` type is erased, the
357 /// parameter `erased_self_ty` must be supplied to indicate what type
358 /// has been used to represent `Self` in the predicates
359 /// themselves. This should really be a unique type; `FreshTy(0)` is a
362 /// NB: in some cases, particularly around higher-ranked bounds,
363 /// this function returns a kind of conservative approximation.
364 /// That is, all regions returned by this function are definitely
365 /// required, but there may be other region bounds that are not
366 /// returned, as well as requirements like `for<'a> T: 'a`.
368 /// Requires that trait definitions have been processed so that we can
369 /// elaborate predicates and walk supertraits.
371 /// FIXME callers may only have a &[Predicate], not a Vec, so that's
372 /// what this code should accept.
373 pub fn required_region_bounds(self,
374 erased_self_ty: Ty<'tcx>,
375 predicates: Vec<ty::Predicate<'tcx>>)
376 -> Vec<ty::Region<'tcx>> {
377 debug!("required_region_bounds(erased_self_ty={:?}, predicates={:?})",
381 assert!(!erased_self_ty.has_escaping_regions());
383 traits::elaborate_predicates(self, predicates)
384 .filter_map(|predicate| {
386 ty::Predicate::Projection(..) |
387 ty::Predicate::Trait(..) |
388 ty::Predicate::Equate(..) |
389 ty::Predicate::Subtype(..) |
390 ty::Predicate::WellFormed(..) |
391 ty::Predicate::ObjectSafe(..) |
392 ty::Predicate::ClosureKind(..) |
393 ty::Predicate::RegionOutlives(..) |
394 ty::Predicate::ConstEvaluatable(..) => {
397 ty::Predicate::TypeOutlives(ty::Binder(ty::OutlivesPredicate(t, r))) => {
398 // Search for a bound of the form `erased_self_ty
399 // : 'a`, but be wary of something like `for<'a>
400 // erased_self_ty : 'a` (we interpret a
401 // higher-ranked bound like that as 'static,
402 // though at present the code in `fulfill.rs`
403 // considers such bounds to be unsatisfiable, so
404 // it's kind of a moot point since you could never
405 // construct such an object, but this seems
406 // correct even if that code changes).
407 if t == erased_self_ty && !r.has_escaping_regions() {
418 /// Calculate the destructor of a given type.
419 pub fn calculate_dtor(
422 validate: &mut dyn FnMut(Self, DefId) -> Result<(), ErrorReported>
423 ) -> Option<ty::Destructor> {
424 let drop_trait = if let Some(def_id) = self.lang_items().drop_trait() {
430 ty::maps::queries::coherent_trait::ensure(self, drop_trait);
432 let mut dtor_did = None;
433 let ty = self.type_of(adt_did);
434 self.for_each_relevant_impl(drop_trait, ty, |impl_did| {
435 if let Some(item) = self.associated_items(impl_did).next() {
436 if let Ok(()) = validate(self, impl_did) {
437 dtor_did = Some(item.def_id);
442 Some(ty::Destructor { did: dtor_did? })
445 /// Return the set of types that are required to be alive in
446 /// order to run the destructor of `def` (see RFCs 769 and
449 /// Note that this returns only the constraints for the
450 /// destructor of `def` itself. For the destructors of the
451 /// contents, you need `adt_dtorck_constraint`.
452 pub fn destructor_constraints(self, def: &'tcx ty::AdtDef)
453 -> Vec<ty::subst::Kind<'tcx>>
455 let dtor = match def.destructor(self) {
457 debug!("destructor_constraints({:?}) - no dtor", def.did);
460 Some(dtor) => dtor.did
463 // RFC 1238: if the destructor method is tagged with the
464 // attribute `unsafe_destructor_blind_to_params`, then the
465 // compiler is being instructed to *assume* that the
466 // destructor will not access borrowed data,
467 // even if such data is otherwise reachable.
469 // Such access can be in plain sight (e.g. dereferencing
470 // `*foo.0` of `Foo<'a>(&'a u32)`) or indirectly hidden
471 // (e.g. calling `foo.0.clone()` of `Foo<T:Clone>`).
472 if self.has_attr(dtor, "unsafe_destructor_blind_to_params") {
473 debug!("destructor_constraint({:?}) - blind", def.did);
477 let impl_def_id = self.associated_item(dtor).container.id();
478 let impl_generics = self.generics_of(impl_def_id);
480 // We have a destructor - all the parameters that are not
481 // pure_wrt_drop (i.e, don't have a #[may_dangle] attribute)
484 // We need to return the list of parameters from the ADTs
485 // generics/substs that correspond to impure parameters on the
486 // impl's generics. This is a bit ugly, but conceptually simple:
488 // Suppose our ADT looks like the following
490 // struct S<X, Y, Z>(X, Y, Z);
494 // impl<#[may_dangle] P0, P1, P2> Drop for S<P1, P2, P0>
496 // We want to return the parameters (X, Y). For that, we match
497 // up the item-substs <X, Y, Z> with the substs on the impl ADT,
498 // <P1, P2, P0>, and then look up which of the impl substs refer to
499 // parameters marked as pure.
501 let impl_substs = match self.type_of(impl_def_id).sty {
502 ty::TyAdt(def_, substs) if def_ == def => substs,
506 let item_substs = match self.type_of(def.did).sty {
507 ty::TyAdt(def_, substs) if def_ == def => substs,
511 let result = item_substs.iter().zip(impl_substs.iter())
514 UnpackedKind::Lifetime(&ty::RegionKind::ReEarlyBound(ref ebr)) => {
515 !impl_generics.region_param(ebr, self).pure_wrt_drop
517 UnpackedKind::Type(&ty::TyS {
518 sty: ty::TypeVariants::TyParam(ref pt), ..
520 !impl_generics.type_param(pt, self).pure_wrt_drop
522 UnpackedKind::Lifetime(_) | UnpackedKind::Type(_) => {
523 // not a type or region param - this should be reported
528 }).map(|(&item_param, _)| item_param).collect();
529 debug!("destructor_constraint({:?}) = {:?}", def.did, result);
533 /// Return a set of constraints that needs to be satisfied in
534 /// order for `ty` to be valid for destruction.
535 pub fn dtorck_constraint_for_ty(self,
540 -> Result<ty::DtorckConstraint<'tcx>, ErrorReported>
542 debug!("dtorck_constraint_for_ty({:?}, {:?}, {:?}, {:?})",
543 span, for_ty, depth, ty);
545 if depth >= self.sess.recursion_limit.get() {
546 let mut err = struct_span_err!(
547 self.sess, span, E0320,
548 "overflow while adding drop-check rules for {}", for_ty);
549 err.note(&format!("overflowed on {}", ty));
551 return Err(ErrorReported);
554 let result = match ty.sty {
555 ty::TyBool | ty::TyChar | ty::TyInt(_) | ty::TyUint(_) |
556 ty::TyFloat(_) | ty::TyStr | ty::TyNever | ty::TyForeign(..) |
557 ty::TyRawPtr(..) | ty::TyRef(..) | ty::TyFnDef(..) | ty::TyFnPtr(_) |
558 ty::TyGeneratorWitness(..) => {
559 // these types never have a destructor
560 Ok(ty::DtorckConstraint::empty())
563 ty::TyArray(ety, _) | ty::TySlice(ety) => {
564 // single-element containers, behave like their element
565 self.dtorck_constraint_for_ty(span, for_ty, depth+1, ety)
568 ty::TyTuple(tys, _) => {
569 tys.iter().map(|ty| {
570 self.dtorck_constraint_for_ty(span, for_ty, depth+1, ty)
574 ty::TyClosure(def_id, substs) => {
575 substs.upvar_tys(def_id, self).map(|ty| {
576 self.dtorck_constraint_for_ty(span, for_ty, depth+1, ty)
580 ty::TyGenerator(def_id, substs, _) => {
581 // Note that the interior types are ignored here.
582 // Any type reachable inside the interior must also be reachable
583 // through the upvars.
584 substs.upvar_tys(def_id, self).map(|ty| {
585 self.dtorck_constraint_for_ty(span, for_ty, depth+1, ty)
589 ty::TyAdt(def, substs) => {
590 let ty::DtorckConstraint {
591 dtorck_types, outlives
592 } = self.at(span).adt_dtorck_constraint(def.did);
593 Ok(ty::DtorckConstraint {
594 // FIXME: we can try to recursively `dtorck_constraint_on_ty`
595 // there, but that needs some way to handle cycles.
596 dtorck_types: dtorck_types.subst(self, substs),
597 outlives: outlives.subst(self, substs)
601 // Objects must be alive in order for their destructor
603 ty::TyDynamic(..) => Ok(ty::DtorckConstraint {
604 outlives: vec![ty.into()],
605 dtorck_types: vec![],
608 // Types that can't be resolved. Pass them forward.
609 ty::TyProjection(..) | ty::TyAnon(..) | ty::TyParam(..) => {
610 Ok(ty::DtorckConstraint {
612 dtorck_types: vec![ty],
616 ty::TyInfer(..) | ty::TyError => {
617 self.sess.delay_span_bug(span, "unresolved type in dtorck");
622 debug!("dtorck_constraint_for_ty({:?}) = {:?}", ty, result);
626 pub fn is_closure(self, def_id: DefId) -> bool {
627 self.def_key(def_id).disambiguated_data.data == DefPathData::ClosureExpr
630 /// Given the `DefId` of a fn or closure, returns the `DefId` of
631 /// the innermost fn item that the closure is contained within.
632 /// This is a significant def-id because, when we do
633 /// type-checking, we type-check this fn item and all of its
634 /// (transitive) closures together. Therefore, when we fetch the
635 /// `typeck_tables_of` the closure, for example, we really wind up
636 /// fetching the `typeck_tables_of` the enclosing fn item.
637 pub fn closure_base_def_id(self, def_id: DefId) -> DefId {
638 let mut def_id = def_id;
639 while self.is_closure(def_id) {
640 def_id = self.parent_def_id(def_id).unwrap_or_else(|| {
641 bug!("closure {:?} has no parent", def_id);
647 /// Given the def-id and substs a closure, creates the type of
648 /// `self` argument that the closure expects. For example, for a
649 /// `Fn` closure, this would return a reference type `&T` where
652 /// Returns `None` if this closure's kind has not yet been inferred.
653 /// This should only be possible during type checking.
655 /// Note that the return value is a late-bound region and hence
656 /// wrapped in a binder.
657 pub fn closure_env_ty(self,
658 closure_def_id: DefId,
659 closure_substs: ty::ClosureSubsts<'tcx>)
660 -> Option<ty::Binder<Ty<'tcx>>>
662 let closure_ty = self.mk_closure(closure_def_id, closure_substs);
663 let env_region = ty::ReLateBound(ty::DebruijnIndex::new(1), ty::BrEnv);
664 let closure_kind_ty = closure_substs.closure_kind_ty(closure_def_id, self);
665 let closure_kind = closure_kind_ty.to_opt_closure_kind()?;
666 let env_ty = match closure_kind {
667 ty::ClosureKind::Fn => self.mk_imm_ref(self.mk_region(env_region), closure_ty),
668 ty::ClosureKind::FnMut => self.mk_mut_ref(self.mk_region(env_region), closure_ty),
669 ty::ClosureKind::FnOnce => closure_ty,
671 Some(ty::Binder(env_ty))
674 /// Given the def-id of some item that has no type parameters, make
675 /// a suitable "empty substs" for it.
676 pub fn empty_substs_for_def_id(self, item_def_id: DefId) -> &'tcx ty::Substs<'tcx> {
677 ty::Substs::for_item(self, item_def_id,
678 |_, _| self.types.re_erased,
680 bug!("empty_substs_for_def_id: {:?} has type parameters", item_def_id)
684 pub fn const_usize(&self, val: u16) -> ConstInt {
685 match self.sess.target.usize_ty {
686 ast::UintTy::U16 => ConstInt::Usize(ConstUsize::Us16(val as u16)),
687 ast::UintTy::U32 => ConstInt::Usize(ConstUsize::Us32(val as u32)),
688 ast::UintTy::U64 => ConstInt::Usize(ConstUsize::Us64(val as u64)),
693 /// Check if the node pointed to by def_id is a mutable static item
694 pub fn is_static_mut(&self, def_id: DefId) -> bool {
695 if let Some(node) = self.hir.get_if_local(def_id) {
697 Node::NodeItem(&hir::Item {
698 node: hir::ItemStatic(_, hir::MutMutable, _), ..
700 Node::NodeForeignItem(&hir::ForeignItem {
701 node: hir::ForeignItemStatic(_, mutbl), ..
706 match self.describe_def(def_id) {
707 Some(Def::Static(_, mutbl)) => mutbl,
714 pub struct TypeIdHasher<'a, 'gcx: 'a+'tcx, 'tcx: 'a, W> {
715 tcx: TyCtxt<'a, 'gcx, 'tcx>,
716 state: StableHasher<W>,
719 impl<'a, 'gcx, 'tcx, W> TypeIdHasher<'a, 'gcx, 'tcx, W>
720 where W: StableHasherResult
722 pub fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Self {
723 TypeIdHasher { tcx: tcx, state: StableHasher::new() }
726 pub fn finish(self) -> W {
730 pub fn hash<T: Hash>(&mut self, x: T) {
731 x.hash(&mut self.state);
734 fn hash_discriminant_u8<T>(&mut self, x: &T) {
736 intrinsics::discriminant_value(x)
739 assert_eq!(v, b as u64);
743 fn def_id(&mut self, did: DefId) {
744 // Hash the DefPath corresponding to the DefId, which is independent
745 // of compiler internal state. We already have a stable hash value of
746 // all DefPaths available via tcx.def_path_hash(), so we just feed that
748 let hash = self.tcx.def_path_hash(did);
753 impl<'a, 'gcx, 'tcx, W> TypeVisitor<'tcx> for TypeIdHasher<'a, 'gcx, 'tcx, W>
754 where W: StableHasherResult
756 fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool {
757 // Distinguish between the Ty variants uniformly.
758 self.hash_discriminant_u8(&ty.sty);
761 TyInt(i) => self.hash(i),
762 TyUint(u) => self.hash(u),
763 TyFloat(f) => self.hash(f),
765 self.hash_discriminant_u8(&n.val);
767 ConstVal::Integral(x) => self.hash(x.to_u64().unwrap()),
768 ConstVal::Unevaluated(def_id, _) => self.def_id(def_id),
769 _ => bug!("arrays should not have {:?} as length", n)
773 TyRef(_, m) => self.hash(m.mutbl),
774 TyClosure(def_id, _) |
775 TyGenerator(def_id, _, _) |
777 TyFnDef(def_id, _) => self.def_id(def_id),
778 TyAdt(d, _) => self.def_id(d.did),
779 TyForeign(def_id) => self.def_id(def_id),
781 self.hash(f.unsafety());
783 self.hash(f.variadic());
784 self.hash(f.inputs().skip_binder().len());
786 TyDynamic(ref data, ..) => {
787 if let Some(p) = data.principal() {
788 self.def_id(p.def_id());
790 for d in data.auto_traits() {
794 TyGeneratorWitness(tys) => {
795 self.hash(tys.skip_binder().len());
797 TyTuple(tys, defaulted) => {
798 self.hash(tys.len());
799 self.hash(defaulted);
803 self.hash(p.name.as_str());
805 TyProjection(ref data) => {
806 self.def_id(data.item_def_id);
815 TyInfer(_) => bug!("TypeIdHasher: unexpected type {}", ty)
818 ty.super_visit_with(self)
821 fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
822 self.hash_discriminant_u8(r);
827 // No variant fields to hash for these ...
829 ty::ReLateBound(db, ty::BrAnon(i)) => {
833 ty::ReEarlyBound(ty::EarlyBoundRegion { def_id, .. }) => {
837 ty::ReClosureBound(..) |
838 ty::ReLateBound(..) |
842 ty::ReSkolemized(..) => {
843 bug!("TypeIdHasher: unexpected region {:?}", r)
849 fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, x: &ty::Binder<T>) -> bool {
850 // Anonymize late-bound regions so that, for example:
851 // `for<'a, b> fn(&'a &'b T)` and `for<'a, b> fn(&'b &'a T)`
852 // result in the same TypeId (the two types are equivalent).
853 self.tcx.anonymize_late_bound_regions(x).super_visit_with(self)
857 impl<'a, 'tcx> ty::TyS<'tcx> {
858 pub fn moves_by_default(&'tcx self,
859 tcx: TyCtxt<'a, 'tcx, 'tcx>,
860 param_env: ty::ParamEnv<'tcx>,
863 !tcx.at(span).is_copy_raw(param_env.and(self))
866 pub fn is_sized(&'tcx self,
867 tcx: TyCtxt<'a, 'tcx, 'tcx>,
868 param_env: ty::ParamEnv<'tcx>,
871 tcx.at(span).is_sized_raw(param_env.and(self))
874 pub fn is_freeze(&'tcx self,
875 tcx: TyCtxt<'a, 'tcx, 'tcx>,
876 param_env: ty::ParamEnv<'tcx>,
879 tcx.at(span).is_freeze_raw(param_env.and(self))
882 /// If `ty.needs_drop(...)` returns `true`, then `ty` is definitely
883 /// non-copy and *might* have a destructor attached; if it returns
884 /// `false`, then `ty` definitely has no destructor (i.e. no drop glue).
886 /// (Note that this implies that if `ty` has a destructor attached,
887 /// then `needs_drop` will definitely return `true` for `ty`.)
889 pub fn needs_drop(&'tcx self,
890 tcx: TyCtxt<'a, 'tcx, 'tcx>,
891 param_env: ty::ParamEnv<'tcx>)
893 tcx.needs_drop_raw(param_env.and(self))
896 /// Check whether a type is representable. This means it cannot contain unboxed
897 /// structural recursion. This check is needed for structs and enums.
898 pub fn is_representable(&'tcx self,
899 tcx: TyCtxt<'a, 'tcx, 'tcx>,
901 -> Representability {
903 // Iterate until something non-representable is found
904 fn fold_repr<It: Iterator<Item=Representability>>(iter: It) -> Representability {
905 iter.fold(Representability::Representable, |r1, r2| {
907 (Representability::SelfRecursive(v1),
908 Representability::SelfRecursive(v2)) => {
909 Representability::SelfRecursive(v1.iter().map(|s| *s).chain(v2).collect())
911 (r1, r2) => cmp::max(r1, r2)
916 fn are_inner_types_recursive<'a, 'tcx>(
917 tcx: TyCtxt<'a, 'tcx, 'tcx>, sp: Span,
918 seen: &mut Vec<Ty<'tcx>>,
919 representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>,
924 TyTuple(ref ts, _) => {
925 // Find non representable
926 fold_repr(ts.iter().map(|ty| {
927 is_type_structurally_recursive(tcx, sp, seen, representable_cache, ty)
930 // Fixed-length vectors.
931 // FIXME(#11924) Behavior undecided for zero-length vectors.
933 is_type_structurally_recursive(tcx, sp, seen, representable_cache, ty)
935 TyAdt(def, substs) => {
936 // Find non representable fields with their spans
937 fold_repr(def.all_fields().map(|field| {
938 let ty = field.ty(tcx, substs);
939 let span = tcx.hir.span_if_local(field.did).unwrap_or(sp);
940 match is_type_structurally_recursive(tcx, span, seen,
941 representable_cache, ty)
943 Representability::SelfRecursive(_) => {
944 Representability::SelfRecursive(vec![span])
951 // this check is run on type definitions, so we don't expect
952 // to see closure types
953 bug!("requires check invoked on inapplicable type: {:?}", ty)
955 _ => Representability::Representable,
959 fn same_struct_or_enum<'tcx>(ty: Ty<'tcx>, def: &'tcx ty::AdtDef) -> bool {
961 TyAdt(ty_def, _) => {
968 fn same_type<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
969 match (&a.sty, &b.sty) {
970 (&TyAdt(did_a, substs_a), &TyAdt(did_b, substs_b)) => {
975 substs_a.types().zip(substs_b.types()).all(|(a, b)| same_type(a, b))
981 // Does the type `ty` directly (without indirection through a pointer)
982 // contain any types on stack `seen`?
983 fn is_type_structurally_recursive<'a, 'tcx>(
984 tcx: TyCtxt<'a, 'tcx, 'tcx>,
986 seen: &mut Vec<Ty<'tcx>>,
987 representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>,
988 ty: Ty<'tcx>) -> Representability
990 debug!("is_type_structurally_recursive: {:?} {:?}", ty, sp);
991 if let Some(representability) = representable_cache.get(ty) {
992 debug!("is_type_structurally_recursive: {:?} {:?} - (cached) {:?}",
993 ty, sp, representability);
994 return representability.clone();
997 let representability = is_type_structurally_recursive_inner(
998 tcx, sp, seen, representable_cache, ty);
1000 representable_cache.insert(ty, representability.clone());
1004 fn is_type_structurally_recursive_inner<'a, 'tcx>(
1005 tcx: TyCtxt<'a, 'tcx, 'tcx>,
1007 seen: &mut Vec<Ty<'tcx>>,
1008 representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>,
1009 ty: Ty<'tcx>) -> Representability
1014 // Iterate through stack of previously seen types.
1015 let mut iter = seen.iter();
1017 // The first item in `seen` is the type we are actually curious about.
1018 // We want to return SelfRecursive if this type contains itself.
1019 // It is important that we DON'T take generic parameters into account
1020 // for this check, so that Bar<T> in this example counts as SelfRecursive:
1023 // struct Bar<T> { x: Bar<Foo> }
1025 if let Some(&seen_type) = iter.next() {
1026 if same_struct_or_enum(seen_type, def) {
1027 debug!("SelfRecursive: {:?} contains {:?}",
1030 return Representability::SelfRecursive(vec![sp]);
1034 // We also need to know whether the first item contains other types
1035 // that are structurally recursive. If we don't catch this case, we
1036 // will recurse infinitely for some inputs.
1038 // It is important that we DO take generic parameters into account
1039 // here, so that code like this is considered SelfRecursive, not
1040 // ContainsRecursive:
1042 // struct Foo { Option<Option<Foo>> }
1044 for &seen_type in iter {
1045 if same_type(ty, seen_type) {
1046 debug!("ContainsRecursive: {:?} contains {:?}",
1049 return Representability::ContainsRecursive;
1054 // For structs and enums, track all previously seen types by pushing them
1055 // onto the 'seen' stack.
1057 let out = are_inner_types_recursive(tcx, sp, seen, representable_cache, ty);
1062 // No need to push in other cases.
1063 are_inner_types_recursive(tcx, sp, seen, representable_cache, ty)
1068 debug!("is_type_representable: {:?}", self);
1070 // To avoid a stack overflow when checking an enum variant or struct that
1071 // contains a different, structurally recursive type, maintain a stack
1072 // of seen types and check recursion for each of them (issues #3008, #3779).
1073 let mut seen: Vec<Ty> = Vec::new();
1074 let mut representable_cache = FxHashMap();
1075 let r = is_type_structurally_recursive(
1076 tcx, sp, &mut seen, &mut representable_cache, self);
1077 debug!("is_type_representable: {:?} is {:?}", self, r);
1082 fn is_copy_raw<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
1083 query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>)
1086 let (param_env, ty) = query.into_parts();
1087 let trait_def_id = tcx.require_lang_item(lang_items::CopyTraitLangItem);
1089 .enter(|infcx| traits::type_known_to_meet_bound(&infcx,
1096 fn is_sized_raw<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
1097 query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>)
1100 let (param_env, ty) = query.into_parts();
1101 let trait_def_id = tcx.require_lang_item(lang_items::SizedTraitLangItem);
1103 .enter(|infcx| traits::type_known_to_meet_bound(&infcx,
1110 fn is_freeze_raw<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
1111 query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>)
1114 let (param_env, ty) = query.into_parts();
1115 let trait_def_id = tcx.require_lang_item(lang_items::FreezeTraitLangItem);
1117 .enter(|infcx| traits::type_known_to_meet_bound(&infcx,
1124 fn needs_drop_raw<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
1125 query: ty::ParamEnvAnd<'tcx, Ty<'tcx>>)
1128 let (param_env, ty) = query.into_parts();
1130 let needs_drop = |ty: Ty<'tcx>| -> bool {
1131 match ty::queries::needs_drop_raw::try_get(tcx, DUMMY_SP, param_env.and(ty)) {
1134 // Cycles should be reported as an error by `check_representable`.
1136 // Consider the type as not needing drop in the meanwhile to
1137 // avoid further errors.
1139 // In case we forgot to emit a bug elsewhere, delay our
1140 // diagnostic to get emitted as a compiler bug.
1147 assert!(!ty.needs_infer());
1150 // Fast-path for primitive types
1151 ty::TyInfer(ty::FreshIntTy(_)) | ty::TyInfer(ty::FreshFloatTy(_)) |
1152 ty::TyBool | ty::TyInt(_) | ty::TyUint(_) | ty::TyFloat(_) | ty::TyNever |
1153 ty::TyFnDef(..) | ty::TyFnPtr(_) | ty::TyChar | ty::TyGeneratorWitness(..) |
1154 ty::TyRawPtr(_) | ty::TyRef(..) | ty::TyStr => false,
1156 // Foreign types can never have destructors
1157 ty::TyForeign(..) => false,
1159 // Issue #22536: We first query type_moves_by_default. It sees a
1160 // normalized version of the type, and therefore will definitely
1161 // know whether the type implements Copy (and thus needs no
1162 // cleanup/drop/zeroing) ...
1163 _ if !ty.moves_by_default(tcx, param_env, DUMMY_SP) => false,
1165 // ... (issue #22536 continued) but as an optimization, still use
1166 // prior logic of asking for the structural "may drop".
1168 // FIXME(#22815): Note that this is a conservative heuristic;
1169 // it may report that the type "may drop" when actual type does
1170 // not actually have a destructor associated with it. But since
1171 // the type absolutely did not have the `Copy` bound attached
1172 // (see above), it is sound to treat it as having a destructor.
1174 // User destructors are the only way to have concrete drop types.
1175 ty::TyAdt(def, _) if def.has_dtor(tcx) => true,
1177 // Can refer to a type which may drop.
1178 // FIXME(eddyb) check this against a ParamEnv.
1179 ty::TyDynamic(..) | ty::TyProjection(..) | ty::TyParam(_) |
1180 ty::TyAnon(..) | ty::TyInfer(_) | ty::TyError => true,
1182 // Structural recursion.
1183 ty::TyArray(ty, _) | ty::TySlice(ty) => needs_drop(ty),
1185 ty::TyClosure(def_id, ref substs) => substs.upvar_tys(def_id, tcx).any(needs_drop),
1187 // Pessimistically assume that all generators will require destructors
1188 // as we don't know if a destructor is a noop or not until after the MIR
1189 // state transformation pass
1190 ty::TyGenerator(..) => true,
1192 ty::TyTuple(ref tys, _) => tys.iter().cloned().any(needs_drop),
1194 // unions don't have destructors regardless of the child types
1195 ty::TyAdt(def, _) if def.is_union() => false,
1197 ty::TyAdt(def, substs) =>
1198 def.variants.iter().any(
1199 |variant| variant.fields.iter().any(
1200 |field| needs_drop(field.ty(tcx, substs)))),
1204 pub enum ExplicitSelf<'tcx> {
1206 ByReference(ty::Region<'tcx>, hir::Mutability),
1207 ByRawPointer(hir::Mutability),
1212 impl<'tcx> ExplicitSelf<'tcx> {
1213 /// Categorizes an explicit self declaration like `self: SomeType`
1214 /// into either `self`, `&self`, `&mut self`, `Box<self>`, or
1216 /// This is mainly used to require the arbitrary_self_types feature
1217 /// in the case of `Other`, to improve error messages in the common cases,
1218 /// and to make `Other` non-object-safe.
1223 /// impl<'a> Foo for &'a T {
1224 /// // Legal declarations:
1225 /// fn method1(self: &&'a T); // ExplicitSelf::ByReference
1226 /// fn method2(self: &'a T); // ExplicitSelf::ByValue
1227 /// fn method3(self: Box<&'a T>); // ExplicitSelf::ByBox
1228 /// fn method4(self: Rc<&'a T>); // ExplicitSelf::Other
1230 /// // Invalid cases will be caught by `check_method_receiver`:
1231 /// fn method_err1(self: &'a mut T); // ExplicitSelf::Other
1232 /// fn method_err2(self: &'static T) // ExplicitSelf::ByValue
1233 /// fn method_err3(self: &&T) // ExplicitSelf::ByReference
1237 pub fn determine<P>(
1238 self_arg_ty: Ty<'tcx>,
1240 ) -> ExplicitSelf<'tcx>
1242 P: Fn(Ty<'tcx>) -> bool
1244 use self::ExplicitSelf::*;
1246 match self_arg_ty.sty {
1247 _ if is_self_ty(self_arg_ty) => ByValue,
1248 ty::TyRef(region, ty::TypeAndMut { ty, mutbl }) if is_self_ty(ty) => {
1249 ByReference(region, mutbl)
1251 ty::TyRawPtr(ty::TypeAndMut { ty, mutbl }) if is_self_ty(ty) => {
1254 ty::TyAdt(def, _) if def.is_box() && is_self_ty(self_arg_ty.boxed_ty()) => {
1262 pub fn provide(providers: &mut ty::maps::Providers) {
1263 *providers = ty::maps::Providers {