1 //! This module contains `TyKind` and its major components.
3 #![allow(rustc::usage_of_ty_tykind)]
7 use crate::infer
::canonical
::Canonical
;
8 use crate::ty
::subst
::{GenericArg, InternalSubsts, Subst, SubstsRef}
;
9 use crate::ty
::InferTy
::{self, *}
;
11 self, AdtDef
, DefIdTree
, Discr
, Ty
, TyCtxt
, TypeFlags
, TypeFoldable
, WithConstness
,
13 use crate::ty
::{DelaySpanBugEmitted, List, ParamEnv, TyS}
;
14 use polonius_engine
::Atom
;
15 use rustc_data_structures
::captures
::Captures
;
17 use rustc_hir
::def_id
::DefId
;
18 use rustc_index
::vec
::Idx
;
19 use rustc_macros
::HashStable
;
20 use rustc_span
::symbol
::{kw, Symbol}
;
21 use rustc_target
::abi
::VariantIdx
;
22 use rustc_target
::spec
::abi
;
24 use std
::cmp
::Ordering
;
25 use std
::marker
::PhantomData
;
27 use ty
::util
::IntTypeExt
;
29 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
30 #[derive(HashStable, TypeFoldable, Lift)]
31 pub struct TypeAndMut
<'tcx
> {
33 pub mutbl
: hir
::Mutability
,
36 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
38 /// A "free" region `fr` can be interpreted as "some region
39 /// at least as big as the scope `fr.scope`".
40 pub struct FreeRegion
{
42 pub bound_region
: BoundRegionKind
,
45 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
47 pub enum BoundRegionKind
{
48 /// An anonymous region parameter for a given fn (&T)
51 /// Named region parameters for functions (a in &'a T)
53 /// The `DefId` is needed to distinguish free regions in
54 /// the event of shadowing.
55 BrNamed(DefId
, Symbol
),
57 /// Anonymous region for the implicit env pointer parameter
62 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
64 pub struct BoundRegion
{
65 pub kind
: BoundRegionKind
,
69 /// When canonicalizing, we replace unbound inference variables and free
70 /// regions with anonymous late bound regions. This method asserts that
71 /// we have an anonymous late bound region, which hence may refer to
72 /// a canonical variable.
73 pub fn assert_bound_var(&self) -> BoundVar
{
75 BoundRegionKind
::BrAnon(var
) => BoundVar
::from_u32(var
),
76 _
=> bug
!("bound region is not anonymous"),
81 impl BoundRegionKind
{
82 pub fn is_named(&self) -> bool
{
84 BoundRegionKind
::BrNamed(_
, name
) => name
!= kw
::UnderscoreLifetime
,
90 /// Defines the kinds of types.
92 /// N.B., if you change this, you'll probably want to change the corresponding
93 /// AST structure in `librustc_ast/ast.rs` as well.
94 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable, Debug)]
96 #[rustc_diagnostic_item = "TyKind"]
97 pub enum TyKind
<'tcx
> {
98 /// The primitive boolean type. Written as `bool`.
101 /// The primitive character type; holds a Unicode scalar value
102 /// (a non-surrogate code point). Written as `char`.
105 /// A primitive signed integer type. For example, `i32`.
108 /// A primitive unsigned integer type. For example, `u32`.
111 /// A primitive floating-point type. For example, `f64`.
114 /// Algebraic data types (ADT). For example: structures, enumerations and unions.
116 /// InternalSubsts here, possibly against intuition, *may* contain `Param`s.
117 /// That is, even after substitution it is possible that there are type
118 /// variables. This happens when the `Adt` corresponds to an ADT
119 /// definition and not a concrete use of it.
120 Adt(&'tcx AdtDef
, SubstsRef
<'tcx
>),
122 /// An unsized FFI type that is opaque to Rust. Written as `extern type T`.
125 /// The pointee of a string slice. Written as `str`.
128 /// An array with the given length. Written as `[T; n]`.
129 Array(Ty
<'tcx
>, &'tcx ty
::Const
<'tcx
>),
131 /// The pointee of an array slice. Written as `[T]`.
134 /// A raw pointer. Written as `*mut T` or `*const T`
135 RawPtr(TypeAndMut
<'tcx
>),
137 /// A reference; a pointer with an associated lifetime. Written as
138 /// `&'a mut T` or `&'a T`.
139 Ref(Region
<'tcx
>, Ty
<'tcx
>, hir
::Mutability
),
141 /// The anonymous type of a function declaration/definition. Each
142 /// function has a unique type, which is output (for a function
143 /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
145 /// For example the type of `bar` here:
148 /// fn foo() -> i32 { 1 }
149 /// let bar = foo; // bar: fn() -> i32 {foo}
151 FnDef(DefId
, SubstsRef
<'tcx
>),
153 /// A pointer to a function. Written as `fn() -> i32`.
155 /// For example the type of `bar` here:
158 /// fn foo() -> i32 { 1 }
159 /// let bar: fn() -> i32 = foo;
161 FnPtr(PolyFnSig
<'tcx
>),
163 /// A trait, defined with `trait`.
164 Dynamic(&'tcx List
<Binder
<ExistentialPredicate
<'tcx
>>>, ty
::Region
<'tcx
>),
166 /// The anonymous type of a closure. Used to represent the type of
168 Closure(DefId
, SubstsRef
<'tcx
>),
170 /// The anonymous type of a generator. Used to represent the type of
172 Generator(DefId
, SubstsRef
<'tcx
>, hir
::Movability
),
174 /// A type representing the types stored inside a generator.
175 /// This should only appear in GeneratorInteriors.
176 GeneratorWitness(Binder
<&'tcx List
<Ty
<'tcx
>>>),
178 /// The never type `!`.
181 /// A tuple type. For example, `(i32, bool)`.
182 /// Use `TyS::tuple_fields` to iterate over the field types.
183 Tuple(SubstsRef
<'tcx
>),
185 /// The projection of an associated type. For example,
186 /// `<T as Trait<..>>::N`.
187 Projection(ProjectionTy
<'tcx
>),
189 /// Opaque (`impl Trait`) type found in a return type.
190 /// The `DefId` comes either from
191 /// * the `impl Trait` ast::Ty node,
192 /// * or the `type Foo = impl Trait` declaration
193 /// The substitutions are for the generics of the function in question.
194 /// After typeck, the concrete type can be found in the `types` map.
195 Opaque(DefId
, SubstsRef
<'tcx
>),
197 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}`.
200 /// Bound type variable, used only when preparing a trait query.
201 Bound(ty
::DebruijnIndex
, BoundTy
),
203 /// A placeholder type - universally quantified higher-ranked type.
204 Placeholder(ty
::PlaceholderType
),
206 /// A type variable used during type checking.
209 /// A placeholder for a type which could not be computed; this is
210 /// propagated to avoid useless error messages.
211 Error(DelaySpanBugEmitted
),
216 pub fn is_primitive(&self) -> bool
{
217 matches
!(self, Bool
| Char
| Int(_
) | Uint(_
) | Float(_
))
220 /// Get the article ("a" or "an") to use with this type.
221 pub fn article(&self) -> &'
static str {
223 Int(_
) | Float(_
) | Array(_
, _
) => "an",
224 Adt(def
, _
) if def
.is_enum() => "an",
225 // This should never happen, but ICEing and causing the user's code
226 // to not compile felt too harsh.
233 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
234 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
235 static_assert_size
!(TyKind
<'_
>, 24);
237 /// A closure can be modeled as a struct that looks like:
239 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
243 /// - 'l0...'li and T0...Tj are the generic parameters
244 /// in scope on the function that defined the closure,
245 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
246 /// is rather hackily encoded via a scalar type. See
247 /// `TyS::to_opt_closure_kind` for details.
248 /// - CS represents the *closure signature*, representing as a `fn()`
249 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
250 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
252 /// - U is a type parameter representing the types of its upvars, tupled up
253 /// (borrowed, if appropriate; that is, if an U field represents a by-ref upvar,
254 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
256 /// So, for example, given this function:
258 /// fn foo<'a, T>(data: &'a mut T) {
259 /// do(|| data.count += 1)
262 /// the type of the closure would be something like:
264 /// struct Closure<'a, T, U>(...U);
266 /// Note that the type of the upvar is not specified in the struct.
267 /// You may wonder how the impl would then be able to use the upvar,
268 /// if it doesn't know it's type? The answer is that the impl is
269 /// (conceptually) not fully generic over Closure but rather tied to
270 /// instances with the expected upvar types:
272 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
276 /// You can see that the *impl* fully specified the type of the upvar
277 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
278 /// (Here, I am assuming that `data` is mut-borrowed.)
280 /// Now, the last question you may ask is: Why include the upvar types
281 /// in an extra type parameter? The reason for this design is that the
282 /// upvar types can reference lifetimes that are internal to the
283 /// creating function. In my example above, for example, the lifetime
284 /// `'b` represents the scope of the closure itself; this is some
285 /// subset of `foo`, probably just the scope of the call to the to
286 /// `do()`. If we just had the lifetime/type parameters from the
287 /// enclosing function, we couldn't name this lifetime `'b`. Note that
288 /// there can also be lifetimes in the types of the upvars themselves,
289 /// if one of them happens to be a reference to something that the
290 /// creating fn owns.
292 /// OK, you say, so why not create a more minimal set of parameters
293 /// that just includes the extra lifetime parameters? The answer is
294 /// primarily that it would be hard --- we don't know at the time when
295 /// we create the closure type what the full types of the upvars are,
296 /// nor do we know which are borrowed and which are not. In this
297 /// design, we can just supply a fresh type parameter and figure that
300 /// All right, you say, but why include the type parameters from the
301 /// original function then? The answer is that codegen may need them
302 /// when monomorphizing, and they may not appear in the upvars. A
303 /// closure could capture no variables but still make use of some
304 /// in-scope type parameter with a bound (e.g., if our example above
305 /// had an extra `U: Default`, and the closure called `U::default()`).
307 /// There is another reason. This design (implicitly) prohibits
308 /// closures from capturing themselves (except via a trait
309 /// object). This simplifies closure inference considerably, since it
310 /// means that when we infer the kind of a closure or its upvars, we
311 /// don't have to handle cycles where the decisions we make for
312 /// closure C wind up influencing the decisions we ought to make for
313 /// closure C (which would then require fixed point iteration to
314 /// handle). Plus it fixes an ICE. :P
318 /// Generators are handled similarly in `GeneratorSubsts`. The set of
319 /// type parameters is similar, but `CK` and `CS` are replaced by the
320 /// following type parameters:
322 /// * `GS`: The generator's "resume type", which is the type of the
323 /// argument passed to `resume`, and the type of `yield` expressions
324 /// inside the generator.
325 /// * `GY`: The "yield type", which is the type of values passed to
326 /// `yield` inside the generator.
327 /// * `GR`: The "return type", which is the type of value returned upon
328 /// completion of the generator.
329 /// * `GW`: The "generator witness".
330 #[derive(Copy, Clone, Debug, TypeFoldable)]
331 pub struct ClosureSubsts
<'tcx
> {
332 /// Lifetime and type parameters from the enclosing function,
333 /// concatenated with a tuple containing the types of the upvars.
335 /// These are separated out because codegen wants to pass them around
336 /// when monomorphizing.
337 pub substs
: SubstsRef
<'tcx
>,
340 /// Struct returned by `split()`.
341 pub struct ClosureSubstsParts
<'tcx
, T
> {
342 pub parent_substs
: &'tcx
[GenericArg
<'tcx
>],
343 pub closure_kind_ty
: T
,
344 pub closure_sig_as_fn_ptr_ty
: T
,
345 pub tupled_upvars_ty
: T
,
348 impl<'tcx
> ClosureSubsts
<'tcx
> {
349 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
350 /// for the closure parent, alongside additional closure-specific components.
353 parts
: ClosureSubstsParts
<'tcx
, Ty
<'tcx
>>,
354 ) -> ClosureSubsts
<'tcx
> {
356 substs
: tcx
.mk_substs(
357 parts
.parent_substs
.iter().copied().chain(
358 [parts
.closure_kind_ty
, parts
.closure_sig_as_fn_ptr_ty
, parts
.tupled_upvars_ty
]
360 .map(|&ty
| ty
.into()),
366 /// Divides the closure substs into their respective components.
367 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
368 fn split(self) -> ClosureSubstsParts
<'tcx
, GenericArg
<'tcx
>> {
369 match self.substs
[..] {
370 [ref parent_substs @
.., closure_kind_ty
, closure_sig_as_fn_ptr_ty
, tupled_upvars_ty
] => {
374 closure_sig_as_fn_ptr_ty
,
378 _
=> bug
!("closure substs missing synthetics"),
382 /// Returns `true` only if enough of the synthetic types are known to
383 /// allow using all of the methods on `ClosureSubsts` without panicking.
385 /// Used primarily by `ty::print::pretty` to be able to handle closure
386 /// types that haven't had their synthetic types substituted in.
387 pub fn is_valid(self) -> bool
{
388 self.substs
.len() >= 3
389 && matches
!(self.split().tupled_upvars_ty
.expect_ty().kind(), Tuple(_
))
392 /// Returns the substitutions of the closure's parent.
393 pub fn parent_substs(self) -> &'tcx
[GenericArg
<'tcx
>] {
394 self.split().parent_substs
397 /// Returns an iterator over the list of types of captured paths by the closure.
398 /// In case there was a type error in figuring out the types of the captured path, an
399 /// empty iterator is returned.
401 pub fn upvar_tys(self) -> impl Iterator
<Item
= Ty
<'tcx
>> + 'tcx
{
402 match self.tupled_upvars_ty().kind() {
403 TyKind
::Error(_
) => None
,
404 TyKind
::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
405 TyKind
::Infer(_
) => bug
!("upvar_tys called before capture types are inferred"),
406 ty
=> bug
!("Unexpected representation of upvar types tuple {:?}", ty
),
412 /// Returns the tuple type representing the upvars for this closure.
414 pub fn tupled_upvars_ty(self) -> Ty
<'tcx
> {
415 self.split().tupled_upvars_ty
.expect_ty()
418 /// Returns the closure kind for this closure; may return a type
419 /// variable during inference. To get the closure kind during
420 /// inference, use `infcx.closure_kind(substs)`.
421 pub fn kind_ty(self) -> Ty
<'tcx
> {
422 self.split().closure_kind_ty
.expect_ty()
425 /// Returns the `fn` pointer type representing the closure signature for this
427 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
428 // type is known at the time of the creation of `ClosureSubsts`,
429 // see `rustc_typeck::check::closure`.
430 pub fn sig_as_fn_ptr_ty(self) -> Ty
<'tcx
> {
431 self.split().closure_sig_as_fn_ptr_ty
.expect_ty()
434 /// Returns the closure kind for this closure; only usable outside
435 /// of an inference context, because in that context we know that
436 /// there are no type variables.
438 /// If you have an inference context, use `infcx.closure_kind()`.
439 pub fn kind(self) -> ty
::ClosureKind
{
440 self.kind_ty().to_opt_closure_kind().unwrap()
443 /// Extracts the signature from the closure.
444 pub fn sig(self) -> ty
::PolyFnSig
<'tcx
> {
445 let ty
= self.sig_as_fn_ptr_ty();
447 ty
::FnPtr(sig
) => *sig
,
448 _
=> bug
!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty
.kind()),
453 /// Similar to `ClosureSubsts`; see the above documentation for more.
454 #[derive(Copy, Clone, Debug, TypeFoldable)]
455 pub struct GeneratorSubsts
<'tcx
> {
456 pub substs
: SubstsRef
<'tcx
>,
459 pub struct GeneratorSubstsParts
<'tcx
, T
> {
460 pub parent_substs
: &'tcx
[GenericArg
<'tcx
>],
465 pub tupled_upvars_ty
: T
,
468 impl<'tcx
> GeneratorSubsts
<'tcx
> {
469 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
470 /// for the generator parent, alongside additional generator-specific components.
473 parts
: GeneratorSubstsParts
<'tcx
, Ty
<'tcx
>>,
474 ) -> GeneratorSubsts
<'tcx
> {
476 substs
: tcx
.mk_substs(
477 parts
.parent_substs
.iter().copied().chain(
483 parts
.tupled_upvars_ty
,
486 .map(|&ty
| ty
.into()),
492 /// Divides the generator substs into their respective components.
493 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
494 fn split(self) -> GeneratorSubstsParts
<'tcx
, GenericArg
<'tcx
>> {
495 match self.substs
[..] {
496 [ref parent_substs @
.., resume_ty
, yield_ty
, return_ty
, witness
, tupled_upvars_ty
] => {
497 GeneratorSubstsParts
{
506 _
=> bug
!("generator substs missing synthetics"),
510 /// Returns `true` only if enough of the synthetic types are known to
511 /// allow using all of the methods on `GeneratorSubsts` without panicking.
513 /// Used primarily by `ty::print::pretty` to be able to handle generator
514 /// types that haven't had their synthetic types substituted in.
515 pub fn is_valid(self) -> bool
{
516 self.substs
.len() >= 5
517 && matches
!(self.split().tupled_upvars_ty
.expect_ty().kind(), Tuple(_
))
520 /// Returns the substitutions of the generator's parent.
521 pub fn parent_substs(self) -> &'tcx
[GenericArg
<'tcx
>] {
522 self.split().parent_substs
525 /// This describes the types that can be contained in a generator.
526 /// It will be a type variable initially and unified in the last stages of typeck of a body.
527 /// It contains a tuple of all the types that could end up on a generator frame.
528 /// The state transformation MIR pass may only produce layouts which mention types
529 /// in this tuple. Upvars are not counted here.
530 pub fn witness(self) -> Ty
<'tcx
> {
531 self.split().witness
.expect_ty()
534 /// Returns an iterator over the list of types of captured paths by the generator.
535 /// In case there was a type error in figuring out the types of the captured path, an
536 /// empty iterator is returned.
538 pub fn upvar_tys(self) -> impl Iterator
<Item
= Ty
<'tcx
>> + 'tcx
{
539 match self.tupled_upvars_ty().kind() {
540 TyKind
::Error(_
) => None
,
541 TyKind
::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
542 TyKind
::Infer(_
) => bug
!("upvar_tys called before capture types are inferred"),
543 ty
=> bug
!("Unexpected representation of upvar types tuple {:?}", ty
),
549 /// Returns the tuple type representing the upvars for this generator.
551 pub fn tupled_upvars_ty(self) -> Ty
<'tcx
> {
552 self.split().tupled_upvars_ty
.expect_ty()
555 /// Returns the type representing the resume type of the generator.
556 pub fn resume_ty(self) -> Ty
<'tcx
> {
557 self.split().resume_ty
.expect_ty()
560 /// Returns the type representing the yield type of the generator.
561 pub fn yield_ty(self) -> Ty
<'tcx
> {
562 self.split().yield_ty
.expect_ty()
565 /// Returns the type representing the return type of the generator.
566 pub fn return_ty(self) -> Ty
<'tcx
> {
567 self.split().return_ty
.expect_ty()
570 /// Returns the "generator signature", which consists of its yield
571 /// and return types.
573 /// N.B., some bits of the code prefers to see this wrapped in a
574 /// binder, but it never contains bound regions. Probably this
575 /// function should be removed.
576 pub fn poly_sig(self) -> PolyGenSig
<'tcx
> {
577 ty
::Binder
::dummy(self.sig())
580 /// Returns the "generator signature", which consists of its resume, yield
581 /// and return types.
582 pub fn sig(self) -> GenSig
<'tcx
> {
584 resume_ty
: self.resume_ty(),
585 yield_ty
: self.yield_ty(),
586 return_ty
: self.return_ty(),
591 impl<'tcx
> GeneratorSubsts
<'tcx
> {
592 /// Generator has not been resumed yet.
593 pub const UNRESUMED
: usize = 0;
594 /// Generator has returned or is completed.
595 pub const RETURNED
: usize = 1;
596 /// Generator has been poisoned.
597 pub const POISONED
: usize = 2;
599 const UNRESUMED_NAME
: &'
static str = "Unresumed";
600 const RETURNED_NAME
: &'
static str = "Returned";
601 const POISONED_NAME
: &'
static str = "Panicked";
603 /// The valid variant indices of this generator.
605 pub fn variant_range(&self, def_id
: DefId
, tcx
: TyCtxt
<'tcx
>) -> Range
<VariantIdx
> {
606 // FIXME requires optimized MIR
607 let num_variants
= tcx
.generator_layout(def_id
).unwrap().variant_fields
.len();
608 VariantIdx
::new(0)..VariantIdx
::new(num_variants
)
611 /// The discriminant for the given variant. Panics if the `variant_index` is
614 pub fn discriminant_for_variant(
618 variant_index
: VariantIdx
,
620 // Generators don't support explicit discriminant values, so they are
621 // the same as the variant index.
622 assert
!(self.variant_range(def_id
, tcx
).contains(&variant_index
));
623 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
626 /// The set of all discriminants for the generator, enumerated with their
629 pub fn discriminants(
633 ) -> impl Iterator
<Item
= (VariantIdx
, Discr
<'tcx
>)> + Captures
<'tcx
> {
634 self.variant_range(def_id
, tcx
).map(move |index
| {
635 (index
, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) }
)
639 /// Calls `f` with a reference to the name of the enumerator for the given
641 pub fn variant_name(v
: VariantIdx
) -> Cow
<'
static, str> {
643 Self::UNRESUMED
=> Cow
::from(Self::UNRESUMED_NAME
),
644 Self::RETURNED
=> Cow
::from(Self::RETURNED_NAME
),
645 Self::POISONED
=> Cow
::from(Self::POISONED_NAME
),
646 _
=> Cow
::from(format
!("Suspend{}", v
.as_usize() - 3)),
650 /// The type of the state discriminant used in the generator type.
652 pub fn discr_ty(&self, tcx
: TyCtxt
<'tcx
>) -> Ty
<'tcx
> {
656 /// This returns the types of the MIR locals which had to be stored across suspension points.
657 /// It is calculated in rustc_mir::transform::generator::StateTransform.
658 /// All the types here must be in the tuple in GeneratorInterior.
660 /// The locals are grouped by their variant number. Note that some locals may
661 /// be repeated in multiple variants.
667 ) -> impl Iterator
<Item
= impl Iterator
<Item
= Ty
<'tcx
>> + Captures
<'tcx
>> {
668 let layout
= tcx
.generator_layout(def_id
).unwrap();
669 layout
.variant_fields
.iter().map(move |variant
| {
670 variant
.iter().map(move |field
| layout
.field_tys
[*field
].subst(tcx
, self.substs
))
674 /// This is the types of the fields of a generator which are not stored in a
677 pub fn prefix_tys(self) -> impl Iterator
<Item
= Ty
<'tcx
>> {
682 #[derive(Debug, Copy, Clone)]
683 pub enum UpvarSubsts
<'tcx
> {
684 Closure(SubstsRef
<'tcx
>),
685 Generator(SubstsRef
<'tcx
>),
688 impl<'tcx
> UpvarSubsts
<'tcx
> {
689 /// Returns an iterator over the list of types of captured paths by the closure/generator.
690 /// In case there was a type error in figuring out the types of the captured path, an
691 /// empty iterator is returned.
693 pub fn upvar_tys(self) -> impl Iterator
<Item
= Ty
<'tcx
>> + 'tcx
{
694 let tupled_tys
= match self {
695 UpvarSubsts
::Closure(substs
) => substs
.as_closure().tupled_upvars_ty(),
696 UpvarSubsts
::Generator(substs
) => substs
.as_generator().tupled_upvars_ty(),
699 match tupled_tys
.kind() {
700 TyKind
::Error(_
) => None
,
701 TyKind
::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
702 TyKind
::Infer(_
) => bug
!("upvar_tys called before capture types are inferred"),
703 ty
=> bug
!("Unexpected representation of upvar types tuple {:?}", ty
),
710 pub fn tupled_upvars_ty(self) -> Ty
<'tcx
> {
712 UpvarSubsts
::Closure(substs
) => substs
.as_closure().tupled_upvars_ty(),
713 UpvarSubsts
::Generator(substs
) => substs
.as_generator().tupled_upvars_ty(),
718 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
719 #[derive(HashStable, TypeFoldable)]
720 pub enum ExistentialPredicate
<'tcx
> {
721 /// E.g., `Iterator`.
722 Trait(ExistentialTraitRef
<'tcx
>),
723 /// E.g., `Iterator::Item = T`.
724 Projection(ExistentialProjection
<'tcx
>),
729 impl<'tcx
> ExistentialPredicate
<'tcx
> {
730 /// Compares via an ordering that will not change if modules are reordered or other changes are
731 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
732 pub fn stable_cmp(&self, tcx
: TyCtxt
<'tcx
>, other
: &Self) -> Ordering
{
733 use self::ExistentialPredicate
::*;
734 match (*self, *other
) {
735 (Trait(_
), Trait(_
)) => Ordering
::Equal
,
736 (Projection(ref a
), Projection(ref b
)) => {
737 tcx
.def_path_hash(a
.item_def_id
).cmp(&tcx
.def_path_hash(b
.item_def_id
))
739 (AutoTrait(ref a
), AutoTrait(ref b
)) => {
740 tcx
.trait_def(*a
).def_path_hash
.cmp(&tcx
.trait_def(*b
).def_path_hash
)
742 (Trait(_
), _
) => Ordering
::Less
,
743 (Projection(_
), Trait(_
)) => Ordering
::Greater
,
744 (Projection(_
), _
) => Ordering
::Less
,
745 (AutoTrait(_
), _
) => Ordering
::Greater
,
750 impl<'tcx
> Binder
<ExistentialPredicate
<'tcx
>> {
751 pub fn with_self_ty(&self, tcx
: TyCtxt
<'tcx
>, self_ty
: Ty
<'tcx
>) -> ty
::Predicate
<'tcx
> {
752 use crate::ty
::ToPredicate
;
753 match self.skip_binder() {
754 ExistentialPredicate
::Trait(tr
) => {
755 self.rebind(tr
).with_self_ty(tcx
, self_ty
).without_const().to_predicate(tcx
)
757 ExistentialPredicate
::Projection(p
) => {
758 self.rebind(p
.with_self_ty(tcx
, self_ty
)).to_predicate(tcx
)
760 ExistentialPredicate
::AutoTrait(did
) => {
761 let trait_ref
= self.rebind(ty
::TraitRef
{
763 substs
: tcx
.mk_substs_trait(self_ty
, &[]),
765 trait_ref
.without_const().to_predicate(tcx
)
771 impl<'tcx
> List
<ty
::Binder
<ExistentialPredicate
<'tcx
>>> {
772 /// Returns the "principal `DefId`" of this set of existential predicates.
774 /// A Rust trait object type consists (in addition to a lifetime bound)
775 /// of a set of trait bounds, which are separated into any number
776 /// of auto-trait bounds, and at most one non-auto-trait bound. The
777 /// non-auto-trait bound is called the "principal" of the trait
780 /// Only the principal can have methods or type parameters (because
781 /// auto traits can have neither of them). This is important, because
782 /// it means the auto traits can be treated as an unordered set (methods
783 /// would force an order for the vtable, while relating traits with
784 /// type parameters without knowing the order to relate them in is
785 /// a rather non-trivial task).
787 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
788 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
789 /// are the set `{Sync}`.
791 /// It is also possible to have a "trivial" trait object that
792 /// consists only of auto traits, with no principal - for example,
793 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
794 /// is `{Send, Sync}`, while there is no principal. These trait objects
795 /// have a "trivial" vtable consisting of just the size, alignment,
797 pub fn principal(&self) -> Option
<ty
::Binder
<ExistentialTraitRef
<'tcx
>>> {
799 .map_bound(|this
| match this
{
800 ExistentialPredicate
::Trait(tr
) => Some(tr
),
806 pub fn principal_def_id(&self) -> Option
<DefId
> {
807 self.principal().map(|trait_ref
| trait_ref
.skip_binder().def_id
)
811 pub fn projection_bounds
<'a
>(
813 ) -> impl Iterator
<Item
= ty
::Binder
<ExistentialProjection
<'tcx
>>> + 'a
{
814 self.iter().filter_map(|predicate
| {
816 .map_bound(|pred
| match pred
{
817 ExistentialPredicate
::Projection(projection
) => Some(projection
),
825 pub fn auto_traits
<'a
>(&'a
self) -> impl Iterator
<Item
= DefId
> + 'a
{
826 self.iter().filter_map(|predicate
| match predicate
.skip_binder() {
827 ExistentialPredicate
::AutoTrait(did
) => Some(did
),
833 /// A complete reference to a trait. These take numerous guises in syntax,
834 /// but perhaps the most recognizable form is in a where-clause:
838 /// This would be represented by a trait-reference where the `DefId` is the
839 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
840 /// and `U` as parameter 1.
842 /// Trait references also appear in object types like `Foo<U>`, but in
843 /// that case the `Self` parameter is absent from the substitutions.
844 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
845 #[derive(HashStable, TypeFoldable)]
846 pub struct TraitRef
<'tcx
> {
848 pub substs
: SubstsRef
<'tcx
>,
851 impl<'tcx
> TraitRef
<'tcx
> {
852 pub fn new(def_id
: DefId
, substs
: SubstsRef
<'tcx
>) -> TraitRef
<'tcx
> {
853 TraitRef { def_id, substs }
856 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
857 /// are the parameters defined on trait.
858 pub fn identity(tcx
: TyCtxt
<'tcx
>, def_id
: DefId
) -> TraitRef
<'tcx
> {
859 TraitRef { def_id, substs: InternalSubsts::identity_for_item(tcx, def_id) }
863 pub fn self_ty(&self) -> Ty
<'tcx
> {
864 self.substs
.type_at(0)
870 substs
: SubstsRef
<'tcx
>,
871 ) -> ty
::TraitRef
<'tcx
> {
872 let defs
= tcx
.generics_of(trait_id
);
874 ty
::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
878 pub type PolyTraitRef
<'tcx
> = Binder
<TraitRef
<'tcx
>>;
880 impl<'tcx
> PolyTraitRef
<'tcx
> {
881 pub fn self_ty(&self) -> Binder
<Ty
<'tcx
>> {
882 self.map_bound_ref(|tr
| tr
.self_ty())
885 pub fn def_id(&self) -> DefId
{
886 self.skip_binder().def_id
889 pub fn to_poly_trait_predicate(&self) -> ty
::PolyTraitPredicate
<'tcx
> {
890 self.map_bound(|trait_ref
| ty
::TraitPredicate { trait_ref }
)
894 /// An existential reference to a trait, where `Self` is erased.
895 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
897 /// exists T. T: Trait<'a, 'b, X, Y>
899 /// The substitutions don't include the erased `Self`, only trait
900 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
901 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
902 #[derive(HashStable, TypeFoldable)]
903 pub struct ExistentialTraitRef
<'tcx
> {
905 pub substs
: SubstsRef
<'tcx
>,
908 impl<'tcx
> ExistentialTraitRef
<'tcx
> {
909 pub fn erase_self_ty(
911 trait_ref
: ty
::TraitRef
<'tcx
>,
912 ) -> ty
::ExistentialTraitRef
<'tcx
> {
913 // Assert there is a Self.
914 trait_ref
.substs
.type_at(0);
916 ty
::ExistentialTraitRef
{
917 def_id
: trait_ref
.def_id
,
918 substs
: tcx
.intern_substs(&trait_ref
.substs
[1..]),
922 /// Object types don't have a self type specified. Therefore, when
923 /// we convert the principal trait-ref into a normal trait-ref,
924 /// you must give *some* self type. A common choice is `mk_err()`
925 /// or some placeholder type.
926 pub fn with_self_ty(&self, tcx
: TyCtxt
<'tcx
>, self_ty
: Ty
<'tcx
>) -> ty
::TraitRef
<'tcx
> {
927 // otherwise the escaping vars would be captured by the binder
928 // debug_assert!(!self_ty.has_escaping_bound_vars());
930 ty
::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) }
934 pub type PolyExistentialTraitRef
<'tcx
> = Binder
<ExistentialTraitRef
<'tcx
>>;
936 impl<'tcx
> PolyExistentialTraitRef
<'tcx
> {
937 pub fn def_id(&self) -> DefId
{
938 self.skip_binder().def_id
941 /// Object types don't have a self type specified. Therefore, when
942 /// we convert the principal trait-ref into a normal trait-ref,
943 /// you must give *some* self type. A common choice is `mk_err()`
944 /// or some placeholder type.
945 pub fn with_self_ty(&self, tcx
: TyCtxt
<'tcx
>, self_ty
: Ty
<'tcx
>) -> ty
::PolyTraitRef
<'tcx
> {
946 self.map_bound(|trait_ref
| trait_ref
.with_self_ty(tcx
, self_ty
))
950 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
951 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
952 /// (which would be represented by the type `PolyTraitRef ==
953 /// Binder<TraitRef>`). Note that when we instantiate,
954 /// erase, or otherwise "discharge" these bound vars, we change the
955 /// type from `Binder<T>` to just `T` (see
956 /// e.g., `liberate_late_bound_regions`).
958 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
959 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
960 pub struct Binder
<T
>(T
);
963 /// Wraps `value` in a binder, asserting that `value` does not
964 /// contain any bound vars that would be bound by the
965 /// binder. This is commonly used to 'inject' a value T into a
966 /// different binding level.
967 pub fn dummy
<'tcx
>(value
: T
) -> Binder
<T
>
969 T
: TypeFoldable
<'tcx
>,
971 debug_assert
!(!value
.has_escaping_bound_vars());
975 /// Wraps `value` in a binder, binding higher-ranked vars (if any).
976 pub fn bind(value
: T
) -> Binder
<T
> {
980 /// Wraps `value` in a binder without actually binding any currently
981 /// unbound variables.
983 /// Note that this will shift all debrujin indices of escaping bound variables
984 /// by 1 to avoid accidential captures.
985 pub fn wrap_nonbinding(tcx
: TyCtxt
<'tcx
>, value
: T
) -> Binder
<T
>
987 T
: TypeFoldable
<'tcx
>,
989 if value
.has_escaping_bound_vars() {
990 Binder
::bind(super::fold
::shift_vars(tcx
, value
, 1))
996 /// Skips the binder and returns the "bound" value. This is a
997 /// risky thing to do because it's easy to get confused about
998 /// De Bruijn indices and the like. It is usually better to
999 /// discharge the binder using `no_bound_vars` or
1000 /// `replace_late_bound_regions` or something like
1001 /// that. `skip_binder` is only valid when you are either
1002 /// extracting data that has nothing to do with bound vars, you
1003 /// are doing some sort of test that does not involve bound
1004 /// regions, or you are being very careful about your depth
1007 /// Some examples where `skip_binder` is reasonable:
1009 /// - extracting the `DefId` from a PolyTraitRef;
1010 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1011 /// a type parameter `X`, since the type `X` does not reference any regions
1012 pub fn skip_binder(self) -> T
{
1016 pub fn as_ref(&self) -> Binder
<&T
> {
1020 pub fn map_bound_ref
<F
, U
>(&self, f
: F
) -> Binder
<U
>
1024 self.as_ref().map_bound(f
)
1027 pub fn map_bound
<F
, U
>(self, f
: F
) -> Binder
<U
>
1034 /// Wraps a `value` in a binder, using the same bound variables as the
1035 /// current `Binder`. This should not be used if the new value *changes*
1036 /// the bound variables. Note: the (old or new) value itself does not
1037 /// necessarily need to *name* all the bound variables.
1039 /// This currently doesn't do anything different than `bind`, because we
1040 /// don't actually track bound vars. However, semantically, it is different
1041 /// because bound vars aren't allowed to change here, whereas they are
1042 /// in `bind`. This may be (debug) asserted in the future.
1043 pub fn rebind
<U
>(&self, value
: U
) -> Binder
<U
> {
1047 /// Unwraps and returns the value within, but only if it contains
1048 /// no bound vars at all. (In other words, if this binder --
1049 /// and indeed any enclosing binder -- doesn't bind anything at
1050 /// all.) Otherwise, returns `None`.
1052 /// (One could imagine having a method that just unwraps a single
1053 /// binder, but permits late-bound vars bound by enclosing
1054 /// binders, but that would require adjusting the debruijn
1055 /// indices, and given the shallow binding structure we often use,
1056 /// would not be that useful.)
1057 pub fn no_bound_vars
<'tcx
>(self) -> Option
<T
>
1059 T
: TypeFoldable
<'tcx
>,
1061 if self.0.has_escaping_bound_vars() { None }
else { Some(self.skip_binder()) }
1064 /// Given two things that have the same binder level,
1065 /// and an operation that wraps on their contents, executes the operation
1066 /// and then wraps its result.
1068 /// `f` should consider bound regions at depth 1 to be free, and
1069 /// anything it produces with bound regions at depth 1 will be
1070 /// bound in the resulting return value.
1071 pub fn fuse
<U
, F
, R
>(self, u
: Binder
<U
>, f
: F
) -> Binder
<R
>
1073 F
: FnOnce(T
, U
) -> R
,
1075 Binder(f(self.0, u
.0))
1078 /// Splits the contents into two things that share the same binder
1079 /// level as the original, returning two distinct binders.
1081 /// `f` should consider bound regions at depth 1 to be free, and
1082 /// anything it produces with bound regions at depth 1 will be
1083 /// bound in the resulting return values.
1084 pub fn split
<U
, V
, F
>(self, f
: F
) -> (Binder
<U
>, Binder
<V
>)
1086 F
: FnOnce(T
) -> (U
, V
),
1088 let (u
, v
) = f(self.0);
1089 (Binder(u
), Binder(v
))
1093 impl<T
> Binder
<Option
<T
>> {
1094 pub fn transpose(self) -> Option
<Binder
<T
>> {
1099 /// Represents the projection of an associated type. In explicit UFCS
1100 /// form this would be written `<T as Trait<..>>::N`.
1101 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1102 #[derive(HashStable, TypeFoldable)]
1103 pub struct ProjectionTy
<'tcx
> {
1104 /// The parameters of the associated item.
1105 pub substs
: SubstsRef
<'tcx
>,
1107 /// The `DefId` of the `TraitItem` for the associated type `N`.
1109 /// Note that this is not the `DefId` of the `TraitRef` containing this
1110 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
1111 pub item_def_id
: DefId
,
1114 impl<'tcx
> ProjectionTy
<'tcx
> {
1115 pub fn trait_def_id(&self, tcx
: TyCtxt
<'tcx
>) -> DefId
{
1116 tcx
.associated_item(self.item_def_id
).container
.id()
1119 /// Extracts the underlying trait reference and own substs from this projection.
1120 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1121 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1122 pub fn trait_ref_and_own_substs(
1125 ) -> (ty
::TraitRef
<'tcx
>, &'tcx
[ty
::GenericArg
<'tcx
>]) {
1126 let def_id
= tcx
.associated_item(self.item_def_id
).container
.id();
1127 let trait_generics
= tcx
.generics_of(def_id
);
1129 ty
::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) }
,
1130 &self.substs
[trait_generics
.count()..],
1134 /// Extracts the underlying trait reference from this projection.
1135 /// For example, if this is a projection of `<T as Iterator>::Item`,
1136 /// then this function would return a `T: Iterator` trait reference.
1138 /// WARNING: This will drop the substs for generic associated types
1139 /// consider calling [Self::trait_ref_and_own_substs] to get those
1141 pub fn trait_ref(&self, tcx
: TyCtxt
<'tcx
>) -> ty
::TraitRef
<'tcx
> {
1142 let def_id
= self.trait_def_id(tcx
);
1143 ty
::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1146 pub fn self_ty(&self) -> Ty
<'tcx
> {
1147 self.substs
.type_at(0)
1151 #[derive(Copy, Clone, Debug, TypeFoldable)]
1152 pub struct GenSig
<'tcx
> {
1153 pub resume_ty
: Ty
<'tcx
>,
1154 pub yield_ty
: Ty
<'tcx
>,
1155 pub return_ty
: Ty
<'tcx
>,
1158 pub type PolyGenSig
<'tcx
> = Binder
<GenSig
<'tcx
>>;
1160 impl<'tcx
> PolyGenSig
<'tcx
> {
1161 pub fn resume_ty(&self) -> ty
::Binder
<Ty
<'tcx
>> {
1162 self.map_bound_ref(|sig
| sig
.resume_ty
)
1164 pub fn yield_ty(&self) -> ty
::Binder
<Ty
<'tcx
>> {
1165 self.map_bound_ref(|sig
| sig
.yield_ty
)
1167 pub fn return_ty(&self) -> ty
::Binder
<Ty
<'tcx
>> {
1168 self.map_bound_ref(|sig
| sig
.return_ty
)
1172 /// Signature of a function type, which we have arbitrarily
1173 /// decided to use to refer to the input/output types.
1175 /// - `inputs`: is the list of arguments and their modes.
1176 /// - `output`: is the return type.
1177 /// - `c_variadic`: indicates whether this is a C-variadic function.
1178 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1179 #[derive(HashStable, TypeFoldable)]
1180 pub struct FnSig
<'tcx
> {
1181 pub inputs_and_output
: &'tcx List
<Ty
<'tcx
>>,
1182 pub c_variadic
: bool
,
1183 pub unsafety
: hir
::Unsafety
,
1187 impl<'tcx
> FnSig
<'tcx
> {
1188 pub fn inputs(&self) -> &'tcx
[Ty
<'tcx
>] {
1189 &self.inputs_and_output
[..self.inputs_and_output
.len() - 1]
1192 pub fn output(&self) -> Ty
<'tcx
> {
1193 self.inputs_and_output
[self.inputs_and_output
.len() - 1]
1196 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1198 fn fake() -> FnSig
<'tcx
> {
1200 inputs_and_output
: List
::empty(),
1202 unsafety
: hir
::Unsafety
::Normal
,
1203 abi
: abi
::Abi
::Rust
,
1208 pub type PolyFnSig
<'tcx
> = Binder
<FnSig
<'tcx
>>;
1210 impl<'tcx
> PolyFnSig
<'tcx
> {
1212 pub fn inputs(&self) -> Binder
<&'tcx
[Ty
<'tcx
>]> {
1213 self.map_bound_ref(|fn_sig
| fn_sig
.inputs())
1216 pub fn input(&self, index
: usize) -> ty
::Binder
<Ty
<'tcx
>> {
1217 self.map_bound_ref(|fn_sig
| fn_sig
.inputs()[index
])
1219 pub fn inputs_and_output(&self) -> ty
::Binder
<&'tcx List
<Ty
<'tcx
>>> {
1220 self.map_bound_ref(|fn_sig
| fn_sig
.inputs_and_output
)
1223 pub fn output(&self) -> ty
::Binder
<Ty
<'tcx
>> {
1224 self.map_bound_ref(|fn_sig
| fn_sig
.output())
1226 pub fn c_variadic(&self) -> bool
{
1227 self.skip_binder().c_variadic
1229 pub fn unsafety(&self) -> hir
::Unsafety
{
1230 self.skip_binder().unsafety
1232 pub fn abi(&self) -> abi
::Abi
{
1233 self.skip_binder().abi
1237 pub type CanonicalPolyFnSig
<'tcx
> = Canonical
<'tcx
, Binder
<FnSig
<'tcx
>>>;
1239 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1240 #[derive(HashStable)]
1241 pub struct ParamTy
{
1246 impl<'tcx
> ParamTy
{
1247 pub fn new(index
: u32, name
: Symbol
) -> ParamTy
{
1248 ParamTy { index, name }
1251 pub fn for_self() -> ParamTy
{
1252 ParamTy
::new(0, kw
::SelfUpper
)
1255 pub fn for_def(def
: &ty
::GenericParamDef
) -> ParamTy
{
1256 ParamTy
::new(def
.index
, def
.name
)
1260 pub fn to_ty(self, tcx
: TyCtxt
<'tcx
>) -> Ty
<'tcx
> {
1261 tcx
.mk_ty_param(self.index
, self.name
)
1265 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1266 #[derive(HashStable)]
1267 pub struct ParamConst
{
1272 impl<'tcx
> ParamConst
{
1273 pub fn new(index
: u32, name
: Symbol
) -> ParamConst
{
1274 ParamConst { index, name }
1277 pub fn for_def(def
: &ty
::GenericParamDef
) -> ParamConst
{
1278 ParamConst
::new(def
.index
, def
.name
)
1281 pub fn to_const(self, tcx
: TyCtxt
<'tcx
>, ty
: Ty
<'tcx
>) -> &'tcx ty
::Const
<'tcx
> {
1282 tcx
.mk_const_param(self.index
, self.name
, ty
)
1286 pub type Region
<'tcx
> = &'tcx RegionKind
;
1288 /// Representation of regions. Note that the NLL checker uses a distinct
1289 /// representation of regions. For this reason, it internally replaces all the
1290 /// regions with inference variables -- the index of the variable is then used
1291 /// to index into internal NLL data structures. See `rustc_mir::borrow_check`
1292 /// module for more information.
1294 /// ## The Region lattice within a given function
1296 /// In general, the region lattice looks like
1299 /// static ----------+-----...------+ (greatest)
1301 /// early-bound and | |
1302 /// free regions | |
1305 /// empty(root) placeholder(U1) |
1307 /// | / placeholder(Un)
1312 /// empty(Un) -------- (smallest)
1315 /// Early-bound/free regions are the named lifetimes in scope from the
1316 /// function declaration. They have relationships to one another
1317 /// determined based on the declared relationships from the
1320 /// Note that inference variables and bound regions are not included
1321 /// in this diagram. In the case of inference variables, they should
1322 /// be inferred to some other region from the diagram. In the case of
1323 /// bound regions, they are excluded because they don't make sense to
1324 /// include -- the diagram indicates the relationship between free
1327 /// ## Inference variables
1329 /// During region inference, we sometimes create inference variables,
1330 /// represented as `ReVar`. These will be inferred by the code in
1331 /// `infer::lexical_region_resolve` to some free region from the
1332 /// lattice above (the minimal region that meets the
1335 /// During NLL checking, where regions are defined differently, we
1336 /// also use `ReVar` -- in that case, the index is used to index into
1337 /// the NLL region checker's data structures. The variable may in fact
1338 /// represent either a free region or an inference variable, in that
1341 /// ## Bound Regions
1343 /// These are regions that are stored behind a binder and must be substituted
1344 /// with some concrete region before being used. There are two kind of
1345 /// bound regions: early-bound, which are bound in an item's `Generics`,
1346 /// and are substituted by a `InternalSubsts`, and late-bound, which are part of
1347 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1348 /// the likes of `liberate_late_bound_regions`. The distinction exists
1349 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1351 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1352 /// outside their binder, e.g., in types passed to type inference, and
1353 /// should first be substituted (by placeholder regions, free regions,
1354 /// or region variables).
1356 /// ## Placeholder and Free Regions
1358 /// One often wants to work with bound regions without knowing their precise
1359 /// identity. For example, when checking a function, the lifetime of a borrow
1360 /// can end up being assigned to some region parameter. In these cases,
1361 /// it must be ensured that bounds on the region can't be accidentally
1362 /// assumed without being checked.
1364 /// To do this, we replace the bound regions with placeholder markers,
1365 /// which don't satisfy any relation not explicitly provided.
1367 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1368 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1369 /// to be used. These also support explicit bounds: both the internally-stored
1370 /// *scope*, which the region is assumed to outlive, as well as other
1371 /// relations stored in the `FreeRegionMap`. Note that these relations
1372 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1373 /// `resolve_regions_and_report_errors`.
1375 /// When working with higher-ranked types, some region relations aren't
1376 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1377 /// `RePlaceholder` is designed for this purpose. In these contexts,
1378 /// there's also the risk that some inference variable laying around will
1379 /// get unified with your placeholder region: if you want to check whether
1380 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1381 /// with a placeholder region `'%a`, the variable `'_` would just be
1382 /// instantiated to the placeholder region `'%a`, which is wrong because
1383 /// the inference variable is supposed to satisfy the relation
1384 /// *for every value of the placeholder region*. To ensure that doesn't
1385 /// happen, you can use `leak_check`. This is more clearly explained
1386 /// by the [rustc dev guide].
1388 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1389 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1390 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
1391 #[derive(Clone, PartialEq, Eq, Hash, Copy, TyEncodable, TyDecodable, PartialOrd, Ord)]
1392 pub enum RegionKind
{
1393 /// Region bound in a type or fn declaration which will be
1394 /// substituted 'early' -- that is, at the same time when type
1395 /// parameters are substituted.
1396 ReEarlyBound(EarlyBoundRegion
),
1398 /// Region bound in a function scope, which will be substituted when the
1399 /// function is called.
1400 ReLateBound(ty
::DebruijnIndex
, BoundRegion
),
1402 /// When checking a function body, the types of all arguments and so forth
1403 /// that refer to bound region parameters are modified to refer to free
1404 /// region parameters.
1407 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1410 /// A region variable. Should not exist after typeck.
1413 /// A placeholder region -- basically, the higher-ranked version of `ReFree`.
1414 /// Should not exist after typeck.
1415 RePlaceholder(ty
::PlaceholderRegion
),
1417 /// Empty lifetime is for data that is never accessed. We tag the
1418 /// empty lifetime with a universe -- the idea is that we don't
1419 /// want `exists<'a> { forall<'b> { 'b: 'a } }` to be satisfiable.
1420 /// Therefore, the `'empty` in a universe `U` is less than all
1421 /// regions visible from `U`, but not less than regions not visible
1423 ReEmpty(ty
::UniverseIndex
),
1425 /// Erased region, used by trait selection, in MIR and during codegen.
1429 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
1430 pub struct EarlyBoundRegion
{
1436 /// A **`const`** **v**ariable **ID**.
1437 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1438 pub struct ConstVid
<'tcx
> {
1440 pub phantom
: PhantomData
<&'
tcx ()>,
1443 rustc_index
::newtype_index
! {
1444 /// A **region** (lifetime) **v**ariable **ID**.
1445 pub struct RegionVid
{
1446 DEBUG_FORMAT
= custom
,
1450 impl Atom
for RegionVid
{
1451 fn index(self) -> usize {
1456 rustc_index
::newtype_index
! {
1457 pub struct BoundVar { .. }
1460 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1461 #[derive(HashStable)]
1462 pub struct BoundTy
{
1464 pub kind
: BoundTyKind
,
1467 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1468 #[derive(HashStable)]
1469 pub enum BoundTyKind
{
1474 impl From
<BoundVar
> for BoundTy
{
1475 fn from(var
: BoundVar
) -> Self {
1476 BoundTy { var, kind: BoundTyKind::Anon }
1480 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1481 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1482 #[derive(HashStable, TypeFoldable)]
1483 pub struct ExistentialProjection
<'tcx
> {
1484 pub item_def_id
: DefId
,
1485 pub substs
: SubstsRef
<'tcx
>,
1489 pub type PolyExistentialProjection
<'tcx
> = Binder
<ExistentialProjection
<'tcx
>>;
1491 impl<'tcx
> ExistentialProjection
<'tcx
> {
1492 /// Extracts the underlying existential trait reference from this projection.
1493 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1494 /// then this function would return a `exists T. T: Iterator` existential trait
1496 pub fn trait_ref(&self, tcx
: TyCtxt
<'tcx
>) -> ty
::ExistentialTraitRef
<'tcx
> {
1497 let def_id
= tcx
.associated_item(self.item_def_id
).container
.id();
1498 let subst_count
= tcx
.generics_of(def_id
).count() - 1;
1499 let substs
= tcx
.intern_substs(&self.substs
[..subst_count
]);
1500 ty
::ExistentialTraitRef { def_id, substs }
1503 pub fn with_self_ty(
1507 ) -> ty
::ProjectionPredicate
<'tcx
> {
1508 // otherwise the escaping regions would be captured by the binders
1509 debug_assert
!(!self_ty
.has_escaping_bound_vars());
1511 ty
::ProjectionPredicate
{
1512 projection_ty
: ty
::ProjectionTy
{
1513 item_def_id
: self.item_def_id
,
1514 substs
: tcx
.mk_substs_trait(self_ty
, self.substs
),
1520 pub fn erase_self_ty(
1522 projection_predicate
: ty
::ProjectionPredicate
<'tcx
>,
1524 // Assert there is a Self.
1525 projection_predicate
.projection_ty
.substs
.type_at(0);
1528 item_def_id
: projection_predicate
.projection_ty
.item_def_id
,
1529 substs
: tcx
.intern_substs(&projection_predicate
.projection_ty
.substs
[1..]),
1530 ty
: projection_predicate
.ty
,
1535 impl<'tcx
> PolyExistentialProjection
<'tcx
> {
1536 pub fn with_self_ty(
1540 ) -> ty
::PolyProjectionPredicate
<'tcx
> {
1541 self.map_bound(|p
| p
.with_self_ty(tcx
, self_ty
))
1544 pub fn item_def_id(&self) -> DefId
{
1545 self.skip_binder().item_def_id
1549 /// Region utilities
1551 /// Is this region named by the user?
1552 pub fn has_name(&self) -> bool
{
1554 RegionKind
::ReEarlyBound(ebr
) => ebr
.has_name(),
1555 RegionKind
::ReLateBound(_
, br
) => br
.kind
.is_named(),
1556 RegionKind
::ReFree(fr
) => fr
.bound_region
.is_named(),
1557 RegionKind
::ReStatic
=> true,
1558 RegionKind
::ReVar(..) => false,
1559 RegionKind
::RePlaceholder(placeholder
) => placeholder
.name
.is_named(),
1560 RegionKind
::ReEmpty(_
) => false,
1561 RegionKind
::ReErased
=> false,
1566 pub fn is_late_bound(&self) -> bool
{
1567 matches
!(*self, ty
::ReLateBound(..))
1571 pub fn is_placeholder(&self) -> bool
{
1572 matches
!(*self, ty
::RePlaceholder(..))
1576 pub fn bound_at_or_above_binder(&self, index
: ty
::DebruijnIndex
) -> bool
{
1578 ty
::ReLateBound(debruijn
, _
) => debruijn
>= index
,
1583 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1584 /// innermost binder. That is, if we have something bound at `to_binder`,
1585 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1586 /// when moving a region out from inside binders:
1589 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1590 /// // Binder: D3 D2 D1 ^^
1593 /// Here, the region `'a` would have the De Bruijn index D3,
1594 /// because it is the bound 3 binders out. However, if we wanted
1595 /// to refer to that region `'a` in the second argument (the `_`),
1596 /// those two binders would not be in scope. In that case, we
1597 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1598 /// De Bruijn index of `'a` to D1 (the innermost binder).
1600 /// If we invoke `shift_out_to_binder` and the region is in fact
1601 /// bound by one of the binders we are shifting out of, that is an
1602 /// error (and should fail an assertion failure).
1603 pub fn shifted_out_to_binder(&self, to_binder
: ty
::DebruijnIndex
) -> RegionKind
{
1605 ty
::ReLateBound(debruijn
, r
) => {
1606 ty
::ReLateBound(debruijn
.shifted_out_to_binder(to_binder
), r
)
1612 pub fn type_flags(&self) -> TypeFlags
{
1613 let mut flags
= TypeFlags
::empty();
1617 flags
= flags
| TypeFlags
::HAS_FREE_REGIONS
;
1618 flags
= flags
| TypeFlags
::HAS_FREE_LOCAL_REGIONS
;
1619 flags
= flags
| TypeFlags
::HAS_RE_INFER
;
1621 ty
::RePlaceholder(..) => {
1622 flags
= flags
| TypeFlags
::HAS_FREE_REGIONS
;
1623 flags
= flags
| TypeFlags
::HAS_FREE_LOCAL_REGIONS
;
1624 flags
= flags
| TypeFlags
::HAS_RE_PLACEHOLDER
;
1626 ty
::ReEarlyBound(..) => {
1627 flags
= flags
| TypeFlags
::HAS_FREE_REGIONS
;
1628 flags
= flags
| TypeFlags
::HAS_FREE_LOCAL_REGIONS
;
1629 flags
= flags
| TypeFlags
::HAS_RE_PARAM
;
1631 ty
::ReFree { .. }
=> {
1632 flags
= flags
| TypeFlags
::HAS_FREE_REGIONS
;
1633 flags
= flags
| TypeFlags
::HAS_FREE_LOCAL_REGIONS
;
1635 ty
::ReEmpty(_
) | ty
::ReStatic
=> {
1636 flags
= flags
| TypeFlags
::HAS_FREE_REGIONS
;
1638 ty
::ReLateBound(..) => {
1639 flags
= flags
| TypeFlags
::HAS_RE_LATE_BOUND
;
1642 flags
= flags
| TypeFlags
::HAS_RE_ERASED
;
1646 debug
!("type_flags({:?}) = {:?}", self, flags
);
1651 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1652 /// For example, consider the regions in this snippet of code:
1656 /// ^^ -- early bound, declared on an impl
1658 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1659 /// ^^ ^^ ^ anonymous, late-bound
1660 /// | early-bound, appears in where-clauses
1661 /// late-bound, appears only in fn args
1666 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1667 /// of the impl, and for all the other highlighted regions, it
1668 /// would return the `DefId` of the function. In other cases (not shown), this
1669 /// function might return the `DefId` of a closure.
1670 pub fn free_region_binding_scope(&self, tcx
: TyCtxt
<'_
>) -> DefId
{
1672 ty
::ReEarlyBound(br
) => tcx
.parent(br
.def_id
).unwrap(),
1673 ty
::ReFree(fr
) => fr
.scope
,
1674 _
=> bug
!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1680 impl<'tcx
> TyS
<'tcx
> {
1682 pub fn kind(&self) -> &TyKind
<'tcx
> {
1687 pub fn flags(&self) -> TypeFlags
{
1692 pub fn is_unit(&self) -> bool
{
1694 Tuple(ref tys
) => tys
.is_empty(),
1700 pub fn is_never(&self) -> bool
{
1701 matches
!(self.kind(), Never
)
1705 pub fn is_primitive(&self) -> bool
{
1706 self.kind().is_primitive()
1710 pub fn is_adt(&self) -> bool
{
1711 matches
!(self.kind(), Adt(..))
1715 pub fn is_ref(&self) -> bool
{
1716 matches
!(self.kind(), Ref(..))
1720 pub fn is_ty_var(&self) -> bool
{
1721 matches
!(self.kind(), Infer(TyVar(_
)))
1725 pub fn is_ty_infer(&self) -> bool
{
1726 matches
!(self.kind(), Infer(_
))
1730 pub fn is_phantom_data(&self) -> bool
{
1731 if let Adt(def
, _
) = self.kind() { def.is_phantom_data() }
else { false }
1735 pub fn is_bool(&self) -> bool
{
1736 *self.kind() == Bool
1739 /// Returns `true` if this type is a `str`.
1741 pub fn is_str(&self) -> bool
{
1746 pub fn is_param(&self, index
: u32) -> bool
{
1748 ty
::Param(ref data
) => data
.index
== index
,
1754 pub fn is_slice(&self) -> bool
{
1756 RawPtr(TypeAndMut { ty, .. }
) | Ref(_
, ty
, _
) => matches
!(ty
.kind(), Slice(_
) | Str
),
1762 pub fn is_array(&self) -> bool
{
1763 matches
!(self.kind(), Array(..))
1767 pub fn is_simd(&self) -> bool
{
1769 Adt(def
, _
) => def
.repr
.simd(),
1774 pub fn sequence_element_type(&self, tcx
: TyCtxt
<'tcx
>) -> Ty
<'tcx
> {
1776 Array(ty
, _
) | Slice(ty
) => ty
,
1777 Str
=> tcx
.mk_mach_uint(ty
::UintTy
::U8
),
1778 _
=> bug
!("`sequence_element_type` called on non-sequence value: {}", self),
1782 pub fn simd_size_and_type(&self, tcx
: TyCtxt
<'tcx
>) -> (u64, Ty
<'tcx
>) {
1784 Adt(def
, substs
) => {
1785 let variant
= def
.non_enum_variant();
1786 let f0_ty
= variant
.fields
[0].ty(tcx
, substs
);
1788 match f0_ty
.kind() {
1789 Array(f0_elem_ty
, f0_len
) => {
1790 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1791 // The way we evaluate the `N` in `[T; N]` here only works since we use
1792 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1793 // if we use it in generic code. See the `simd-array-trait` ui test.
1794 (f0_len
.eval_usize(tcx
, ParamEnv
::empty()) as u64, f0_elem_ty
)
1796 _
=> (variant
.fields
.len() as u64, f0_ty
),
1799 _
=> bug
!("`simd_size_and_type` called on invalid type"),
1804 pub fn is_region_ptr(&self) -> bool
{
1805 matches
!(self.kind(), Ref(..))
1809 pub fn is_mutable_ptr(&self) -> bool
{
1812 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. }
)
1813 | Ref(_
, _
, hir
::Mutability
::Mut
)
1817 /// Get the mutability of the reference or `None` when not a reference
1819 pub fn ref_mutability(&self) -> Option
<hir
::Mutability
> {
1821 Ref(_
, _
, mutability
) => Some(*mutability
),
1827 pub fn is_unsafe_ptr(&self) -> bool
{
1828 matches
!(self.kind(), RawPtr(_
))
1831 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1833 pub fn is_any_ptr(&self) -> bool
{
1834 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1838 pub fn is_box(&self) -> bool
{
1840 Adt(def
, _
) => def
.is_box(),
1845 /// Panics if called on any type other than `Box<T>`.
1846 pub fn boxed_ty(&self) -> Ty
<'tcx
> {
1848 Adt(def
, substs
) if def
.is_box() => substs
.type_at(0),
1849 _
=> bug
!("`boxed_ty` is called on non-box type {:?}", self),
1853 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1854 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1855 /// contents are abstract to rustc.)
1857 pub fn is_scalar(&self) -> bool
{
1867 | Infer(IntVar(_
) | FloatVar(_
))
1871 /// Returns `true` if this type is a floating point type.
1873 pub fn is_floating_point(&self) -> bool
{
1874 matches
!(self.kind(), Float(_
) | Infer(FloatVar(_
)))
1878 pub fn is_trait(&self) -> bool
{
1879 matches
!(self.kind(), Dynamic(..))
1883 pub fn is_enum(&self) -> bool
{
1885 Adt(adt_def
, _
) => adt_def
.is_enum(),
1891 pub fn is_closure(&self) -> bool
{
1892 matches
!(self.kind(), Closure(..))
1896 pub fn is_generator(&self) -> bool
{
1897 matches
!(self.kind(), Generator(..))
1901 pub fn is_integral(&self) -> bool
{
1902 matches
!(self.kind(), Infer(IntVar(_
)) | Int(_
) | Uint(_
))
1906 pub fn is_fresh_ty(&self) -> bool
{
1907 matches
!(self.kind(), Infer(FreshTy(_
)))
1911 pub fn is_fresh(&self) -> bool
{
1912 matches
!(self.kind(), Infer(FreshTy(_
) | FreshIntTy(_
) | FreshFloatTy(_
)))
1916 pub fn is_char(&self) -> bool
{
1917 matches
!(self.kind(), Char
)
1921 pub fn is_numeric(&self) -> bool
{
1922 self.is_integral() || self.is_floating_point()
1926 pub fn is_signed(&self) -> bool
{
1927 matches
!(self.kind(), Int(_
))
1931 pub fn is_ptr_sized_integral(&self) -> bool
{
1932 matches
!(self.kind(), Int(ty
::IntTy
::Isize
) | Uint(ty
::UintTy
::Usize
))
1936 pub fn is_machine(&self) -> bool
{
1937 matches
!(self.kind(), Int(..) | Uint(..) | Float(..))
1941 pub fn has_concrete_skeleton(&self) -> bool
{
1942 !matches
!(self.kind(), Param(_
) | Infer(_
) | Error(_
))
1945 /// Returns the type and mutability of `*ty`.
1947 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1948 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
1949 pub fn builtin_deref(&self, explicit
: bool
) -> Option
<TypeAndMut
<'tcx
>> {
1951 Adt(def
, _
) if def
.is_box() => {
1952 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not }
)
1954 Ref(_
, ty
, mutbl
) => Some(TypeAndMut { ty, mutbl: *mutbl }
),
1955 RawPtr(mt
) if explicit
=> Some(*mt
),
1960 /// Returns the type of `ty[i]`.
1961 pub fn builtin_index(&self) -> Option
<Ty
<'tcx
>> {
1963 Array(ty
, _
) | Slice(ty
) => Some(ty
),
1968 pub fn fn_sig(&self, tcx
: TyCtxt
<'tcx
>) -> PolyFnSig
<'tcx
> {
1970 FnDef(def_id
, substs
) => tcx
.fn_sig(*def_id
).subst(tcx
, substs
),
1973 // ignore errors (#54954)
1974 ty
::Binder
::dummy(FnSig
::fake())
1976 Closure(..) => bug
!(
1977 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
1979 _
=> bug
!("Ty::fn_sig() called on non-fn type: {:?}", self),
1984 pub fn is_fn(&self) -> bool
{
1985 matches
!(self.kind(), FnDef(..) | FnPtr(_
))
1989 pub fn is_fn_ptr(&self) -> bool
{
1990 matches
!(self.kind(), FnPtr(_
))
1994 pub fn is_impl_trait(&self) -> bool
{
1995 matches
!(self.kind(), Opaque(..))
1999 pub fn ty_adt_def(&self) -> Option
<&'tcx AdtDef
> {
2001 Adt(adt
, _
) => Some(adt
),
2006 /// Iterates over tuple fields.
2007 /// Panics when called on anything but a tuple.
2008 pub fn tuple_fields(&self) -> impl DoubleEndedIterator
<Item
= Ty
<'tcx
>> {
2010 Tuple(substs
) => substs
.iter().map(|field
| field
.expect_ty()),
2011 _
=> bug
!("tuple_fields called on non-tuple"),
2015 /// Get the `i`-th element of a tuple.
2016 /// Panics when called on anything but a tuple.
2017 pub fn tuple_element_ty(&self, i
: usize) -> Option
<Ty
<'tcx
>> {
2019 Tuple(substs
) => substs
.iter().nth(i
).map(|field
| field
.expect_ty()),
2020 _
=> bug
!("tuple_fields called on non-tuple"),
2024 /// If the type contains variants, returns the valid range of variant indices.
2026 // FIXME: This requires the optimized MIR in the case of generators.
2028 pub fn variant_range(&self, tcx
: TyCtxt
<'tcx
>) -> Option
<Range
<VariantIdx
>> {
2030 TyKind
::Adt(adt
, _
) => Some(adt
.variant_range()),
2031 TyKind
::Generator(def_id
, substs
, _
) => {
2032 Some(substs
.as_generator().variant_range(*def_id
, tcx
))
2038 /// If the type contains variants, returns the variant for `variant_index`.
2039 /// Panics if `variant_index` is out of range.
2041 // FIXME: This requires the optimized MIR in the case of generators.
2043 pub fn discriminant_for_variant(
2046 variant_index
: VariantIdx
,
2047 ) -> Option
<Discr
<'tcx
>> {
2049 TyKind
::Adt(adt
, _
) if adt
.variants
.is_empty() => {
2050 bug
!("discriminant_for_variant called on zero variant enum");
2052 TyKind
::Adt(adt
, _
) if adt
.is_enum() => {
2053 Some(adt
.discriminant_for_variant(tcx
, variant_index
))
2055 TyKind
::Generator(def_id
, substs
, _
) => {
2056 Some(substs
.as_generator().discriminant_for_variant(*def_id
, tcx
, variant_index
))
2062 /// Returns the type of the discriminant of this type.
2063 pub fn discriminant_ty(&'tcx
self, tcx
: TyCtxt
<'tcx
>) -> Ty
<'tcx
> {
2065 ty
::Adt(adt
, _
) if adt
.is_enum() => adt
.repr
.discr_type().to_ty(tcx
),
2066 ty
::Generator(_
, substs
, _
) => substs
.as_generator().discr_ty(tcx
),
2068 ty
::Param(_
) | ty
::Projection(_
) | ty
::Opaque(..) | ty
::Infer(ty
::TyVar(_
)) => {
2070 tcx
.associated_items(tcx
.lang_items().discriminant_kind_trait().unwrap());
2071 let discriminant_def_id
= assoc_items
.in_definition_order().next().unwrap().def_id
;
2072 tcx
.mk_projection(discriminant_def_id
, tcx
.mk_substs([self.into()].iter()))
2091 | ty
::GeneratorWitness(..)
2095 | ty
::Infer(IntVar(_
) | FloatVar(_
)) => tcx
.types
.u8,
2098 | ty
::Placeholder(_
)
2099 | ty
::Infer(FreshTy(_
) | ty
::FreshIntTy(_
) | ty
::FreshFloatTy(_
)) => {
2100 bug
!("`discriminant_ty` applied to unexpected type: {:?}", self)
2105 /// Returns the type of metadata for (potentially fat) pointers to this type.
2106 pub fn ptr_metadata_ty(&'tcx
self, tcx
: TyCtxt
<'tcx
>) -> Ty
<'tcx
> {
2107 // FIXME: should this normalize?
2108 let tail
= tcx
.struct_tail_without_normalization(self);
2111 ty
::Infer(ty
::IntVar(_
) | ty
::FloatVar(_
))
2122 | ty
::GeneratorWitness(..)
2128 // If returned by `struct_tail_without_normalization` this is a unit struct
2129 // without any fields, or not a struct, and therefore is Sized.
2131 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2132 // a.k.a. unit type, which is Sized
2133 | ty
::Tuple(..) => tcx
.types
.unit
,
2135 ty
::Str
| ty
::Slice(_
) => tcx
.types
.usize,
2136 ty
::Dynamic(..) => {
2137 let dyn_metadata
= tcx
.lang_items().dyn_metadata().unwrap();
2138 tcx
.type_of(dyn_metadata
).subst(tcx
, &[tail
.into()])
2144 | ty
::Infer(ty
::TyVar(_
))
2146 | ty
::Placeholder(..)
2147 | ty
::Infer(ty
::FreshTy(_
) | ty
::FreshIntTy(_
) | ty
::FreshFloatTy(_
)) => {
2148 bug
!("`ptr_metadata_ty` applied to unexpected type: {:?}", tail
)
2153 /// When we create a closure, we record its kind (i.e., what trait
2154 /// it implements) into its `ClosureSubsts` using a type
2155 /// parameter. This is kind of a phantom type, except that the
2156 /// most convenient thing for us to are the integral types. This
2157 /// function converts such a special type into the closure
2158 /// kind. To go the other way, use
2159 /// `tcx.closure_kind_ty(closure_kind)`.
2161 /// Note that during type checking, we use an inference variable
2162 /// to represent the closure kind, because it has not yet been
2163 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
2164 /// is complete, that type variable will be unified.
2165 pub fn to_opt_closure_kind(&self) -> Option
<ty
::ClosureKind
> {
2167 Int(int_ty
) => match int_ty
{
2168 ty
::IntTy
::I8
=> Some(ty
::ClosureKind
::Fn
),
2169 ty
::IntTy
::I16
=> Some(ty
::ClosureKind
::FnMut
),
2170 ty
::IntTy
::I32
=> Some(ty
::ClosureKind
::FnOnce
),
2171 _
=> bug
!("cannot convert type `{:?}` to a closure kind", self),
2174 // "Bound" types appear in canonical queries when the
2175 // closure type is not yet known
2176 Bound(..) | Infer(_
) => None
,
2178 Error(_
) => Some(ty
::ClosureKind
::Fn
),
2180 _
=> bug
!("cannot convert type `{:?}` to a closure kind", self),
2184 /// Fast path helper for testing if a type is `Sized`.
2186 /// Returning true means the type is known to be sized. Returning
2187 /// `false` means nothing -- could be sized, might not be.
2189 /// Note that we could never rely on the fact that a type such as `[_]` is
2190 /// trivially `!Sized` because we could be in a type environment with a
2191 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2192 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2193 /// this method doesn't return `Option<bool>`.
2194 pub fn is_trivially_sized(&self, tcx
: TyCtxt
<'tcx
>) -> bool
{
2196 ty
::Infer(ty
::IntVar(_
) | ty
::FloatVar(_
))
2207 | ty
::GeneratorWitness(..)
2211 | ty
::Error(_
) => true,
2213 ty
::Str
| ty
::Slice(_
) | ty
::Dynamic(..) | ty
::Foreign(..) => false,
2215 ty
::Tuple(tys
) => tys
.iter().all(|ty
| ty
.expect_ty().is_trivially_sized(tcx
)),
2217 ty
::Adt(def
, _substs
) => def
.sized_constraint(tcx
).is_empty(),
2219 ty
::Projection(_
) | ty
::Param(_
) | ty
::Opaque(..) => false,
2221 ty
::Infer(ty
::TyVar(_
)) => false,
2224 | ty
::Placeholder(..)
2225 | ty
::Infer(ty
::FreshTy(_
) | ty
::FreshIntTy(_
) | ty
::FreshFloatTy(_
)) => {
2226 bug
!("`is_trivially_sized` applied to unexpected type: {:?}", self)