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0731742a | 1 | //! This module contains `TyKind` and its major components. |
e9174d1e | 2 | |
e1599b0c | 3 | #![allow(rustc::usage_of_ty_tykind)] |
416331ca | 4 | |
60c5eb7d XL |
5 | use self::InferTy::*; |
6 | use self::TyKind::*; | |
7 | ||
9fa01778 | 8 | use crate::infer::canonical::Canonical; |
9fa01778 | 9 | use crate::middle::region; |
dfeec247 | 10 | use crate::mir::interpret::ConstValue; |
ba9703b0 | 11 | use crate::mir::interpret::{LitToConstInput, Scalar}; |
dfeec247 | 12 | use crate::mir::Promoted; |
ba9703b0 | 13 | use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef}; |
dfeec247 XL |
14 | use crate::ty::{ |
15 | self, AdtDef, DefIdTree, Discr, Ty, TyCtxt, TypeFlags, TypeFoldable, WithConstness, | |
16 | }; | |
17 | use crate::ty::{List, ParamEnv, ParamEnvAnd, TyS}; | |
60c5eb7d | 18 | use polonius_engine::Atom; |
74b04a01 | 19 | use rustc_ast::ast::{self, Ident}; |
dfeec247 | 20 | use rustc_data_structures::captures::Captures; |
ba9703b0 | 21 | use rustc_errors::ErrorReported; |
dfeec247 | 22 | use rustc_hir as hir; |
ba9703b0 | 23 | use rustc_hir::def_id::{DefId, LocalDefId}; |
60c5eb7d XL |
24 | use rustc_index::vec::Idx; |
25 | use rustc_macros::HashStable; | |
dfeec247 | 26 | use rustc_span::symbol::{kw, Symbol}; |
ba9703b0 | 27 | use rustc_target::abi::{Size, VariantIdx}; |
60c5eb7d | 28 | use rustc_target::spec::abi; |
48663c56 | 29 | use std::borrow::Cow; |
476ff2be | 30 | use std::cmp::Ordering; |
532ac7d7 | 31 | use std::marker::PhantomData; |
48663c56 | 32 | use std::ops::Range; |
e9174d1e | 33 | |
ba9703b0 XL |
34 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
35 | #[derive(HashStable, TypeFoldable, Lift)] | |
e9174d1e SL |
36 | pub struct TypeAndMut<'tcx> { |
37 | pub ty: Ty<'tcx>, | |
38 | pub mutbl: hir::Mutability, | |
39 | } | |
40 | ||
ba9703b0 XL |
41 | #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, RustcEncodable, RustcDecodable, Copy)] |
42 | #[derive(HashStable)] | |
e9174d1e SL |
43 | /// A "free" region `fr` can be interpreted as "some region |
44 | /// at least as big as the scope `fr.scope`". | |
45 | pub struct FreeRegion { | |
7cac9316 | 46 | pub scope: DefId, |
cc61c64b | 47 | pub bound_region: BoundRegion, |
e9174d1e SL |
48 | } |
49 | ||
ba9703b0 XL |
50 | #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, RustcEncodable, RustcDecodable, Copy)] |
51 | #[derive(HashStable)] | |
e9174d1e SL |
52 | pub enum BoundRegion { |
53 | /// An anonymous region parameter for a given fn (&T) | |
54 | BrAnon(u32), | |
55 | ||
56 | /// Named region parameters for functions (a in &'a T) | |
57 | /// | |
9fa01778 | 58 | /// The `DefId` is needed to distinguish free regions in |
e9174d1e | 59 | /// the event of shadowing. |
e74abb32 | 60 | BrNamed(DefId, Symbol), |
e9174d1e | 61 | |
7cac9316 XL |
62 | /// Anonymous region for the implicit env pointer parameter |
63 | /// to a closure | |
cc61c64b | 64 | BrEnv, |
e9174d1e SL |
65 | } |
66 | ||
7cac9316 XL |
67 | impl BoundRegion { |
68 | pub fn is_named(&self) -> bool { | |
69 | match *self { | |
60c5eb7d | 70 | BoundRegion::BrNamed(_, name) => name != kw::UnderscoreLifetime, |
7cac9316 XL |
71 | _ => false, |
72 | } | |
73 | } | |
a1dfa0c6 XL |
74 | |
75 | /// When canonicalizing, we replace unbound inference variables and free | |
76 | /// regions with anonymous late bound regions. This method asserts that | |
77 | /// we have an anonymous late bound region, which hence may refer to | |
78 | /// a canonical variable. | |
79 | pub fn assert_bound_var(&self) -> BoundVar { | |
80 | match *self { | |
81 | BoundRegion::BrAnon(var) => BoundVar::from_u32(var), | |
82 | _ => bug!("bound region is not anonymous"), | |
83 | } | |
84 | } | |
7cac9316 XL |
85 | } |
86 | ||
0731742a | 87 | /// N.B., if you change this, you'll probably want to change the corresponding |
74b04a01 | 88 | /// AST structure in `librustc_ast/ast.rs` as well. |
ba9703b0 XL |
89 | #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, Debug)] |
90 | #[derive(HashStable)] | |
e74abb32 | 91 | #[rustc_diagnostic_item = "TyKind"] |
b7449926 | 92 | pub enum TyKind<'tcx> { |
e9174d1e | 93 | /// The primitive boolean type. Written as `bool`. |
b7449926 | 94 | Bool, |
e9174d1e SL |
95 | |
96 | /// The primitive character type; holds a Unicode scalar value | |
9fa01778 | 97 | /// (a non-surrogate code point). Written as `char`. |
b7449926 | 98 | Char, |
e9174d1e SL |
99 | |
100 | /// A primitive signed integer type. For example, `i32`. | |
b7449926 | 101 | Int(ast::IntTy), |
e9174d1e SL |
102 | |
103 | /// A primitive unsigned integer type. For example, `u32`. | |
b7449926 | 104 | Uint(ast::UintTy), |
e9174d1e SL |
105 | |
106 | /// A primitive floating-point type. For example, `f64`. | |
b7449926 | 107 | Float(ast::FloatTy), |
e9174d1e | 108 | |
9e0c209e | 109 | /// Structures, enumerations and unions. |
e9174d1e | 110 | /// |
532ac7d7 | 111 | /// InternalSubsts here, possibly against intuition, *may* contain `Param`s. |
e9174d1e | 112 | /// That is, even after substitution it is possible that there are type |
b7449926 | 113 | /// variables. This happens when the `Adt` corresponds to an ADT |
9e0c209e | 114 | /// definition and not a concrete use of it. |
532ac7d7 | 115 | Adt(&'tcx AdtDef, SubstsRef<'tcx>), |
e9174d1e | 116 | |
9fa01778 | 117 | /// An unsized FFI type that is opaque to Rust. Written as `extern type T`. |
b7449926 | 118 | Foreign(DefId), |
abe05a73 | 119 | |
e9174d1e | 120 | /// The pointee of a string slice. Written as `str`. |
b7449926 | 121 | Str, |
e9174d1e SL |
122 | |
123 | /// An array with the given length. Written as `[T; n]`. | |
532ac7d7 | 124 | Array(Ty<'tcx>, &'tcx ty::Const<'tcx>), |
e9174d1e | 125 | |
9fa01778 | 126 | /// The pointee of an array slice. Written as `[T]`. |
b7449926 | 127 | Slice(Ty<'tcx>), |
e9174d1e SL |
128 | |
129 | /// A raw pointer. Written as `*mut T` or `*const T` | |
b7449926 | 130 | RawPtr(TypeAndMut<'tcx>), |
e9174d1e SL |
131 | |
132 | /// A reference; a pointer with an associated lifetime. Written as | |
32a655c1 | 133 | /// `&'a mut T` or `&'a T`. |
b7449926 | 134 | Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability), |
e9174d1e | 135 | |
54a0048b | 136 | /// The anonymous type of a function declaration/definition. Each |
0bf4aa26 XL |
137 | /// function has a unique type, which is output (for a function |
138 | /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`. | |
139 | /// | |
140 | /// For example the type of `bar` here: | |
141 | /// | |
142 | /// ```rust | |
143 | /// fn foo() -> i32 { 1 } | |
144 | /// let bar = foo; // bar: fn() -> i32 {foo} | |
145 | /// ``` | |
532ac7d7 | 146 | FnDef(DefId, SubstsRef<'tcx>), |
54a0048b | 147 | |
9fa01778 | 148 | /// A pointer to a function. Written as `fn() -> i32`. |
0bf4aa26 XL |
149 | /// |
150 | /// For example the type of `bar` here: | |
151 | /// | |
152 | /// ```rust | |
153 | /// fn foo() -> i32 { 1 } | |
154 | /// let bar: fn() -> i32 = foo; | |
155 | /// ``` | |
b7449926 | 156 | FnPtr(PolyFnSig<'tcx>), |
e9174d1e SL |
157 | |
158 | /// A trait, defined with `trait`. | |
b7449926 | 159 | Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>), |
e9174d1e SL |
160 | |
161 | /// The anonymous type of a closure. Used to represent the type of | |
162 | /// `|a| a`. | |
e74abb32 | 163 | Closure(DefId, SubstsRef<'tcx>), |
e9174d1e | 164 | |
ea8adc8c XL |
165 | /// The anonymous type of a generator. Used to represent the type of |
166 | /// `|a| yield a`. | |
60c5eb7d | 167 | Generator(DefId, SubstsRef<'tcx>, hir::Movability), |
ea8adc8c | 168 | |
2c00a5a8 XL |
169 | /// A type representin the types stored inside a generator. |
170 | /// This should only appear in GeneratorInteriors. | |
b7449926 | 171 | GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>), |
2c00a5a8 | 172 | |
5bcae85e | 173 | /// The never type `!` |
b7449926 | 174 | Never, |
5bcae85e | 175 | |
9fa01778 | 176 | /// A tuple type. For example, `(i32, bool)`. |
416331ca | 177 | /// Use `TyS::tuple_fields` to iterate over the field types. |
48663c56 | 178 | Tuple(SubstsRef<'tcx>), |
e9174d1e | 179 | |
9fa01778 | 180 | /// The projection of an associated type. For example, |
e9174d1e | 181 | /// `<T as Trait<..>>::N`. |
b7449926 | 182 | Projection(ProjectionTy<'tcx>), |
e9174d1e | 183 | |
0bf4aa26 XL |
184 | /// A placeholder type used when we do not have enough information |
185 | /// to normalize the projection of an associated type to an | |
186 | /// existing concrete type. Currently only used with chalk-engine. | |
187 | UnnormalizedProjection(ProjectionTy<'tcx>), | |
188 | ||
b7449926 | 189 | /// Opaque (`impl Trait`) type found in a return type. |
0bf4aa26 | 190 | /// The `DefId` comes either from |
8faf50e0 | 191 | /// * the `impl Trait` ast::Ty node, |
416331ca | 192 | /// * or the `type Foo = impl Trait` declaration |
8faf50e0 | 193 | /// The substitutions are for the generics of the function in question. |
476ff2be | 194 | /// After typeck, the concrete type can be found in the `types` map. |
532ac7d7 | 195 | Opaque(DefId, SubstsRef<'tcx>), |
5bcae85e | 196 | |
e9174d1e | 197 | /// A type parameter; for example, `T` in `fn f<T>(x: T) {} |
b7449926 | 198 | Param(ParamTy), |
e9174d1e | 199 | |
a1dfa0c6 XL |
200 | /// Bound type variable, used only when preparing a trait query. |
201 | Bound(ty::DebruijnIndex, BoundTy), | |
202 | ||
203 | /// A placeholder type - universally quantified higher-ranked type. | |
204 | Placeholder(ty::PlaceholderType), | |
205 | ||
0bf4aa26 | 206 | /// A type variable used during type checking. |
b7449926 | 207 | Infer(InferTy), |
e9174d1e SL |
208 | |
209 | /// A placeholder for a type which could not be computed; this is | |
210 | /// propagated to avoid useless error messages. | |
b7449926 | 211 | Error, |
e9174d1e SL |
212 | } |
213 | ||
a1dfa0c6 XL |
214 | // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger. |
215 | #[cfg(target_arch = "x86_64")] | |
48663c56 | 216 | static_assert_size!(TyKind<'_>, 24); |
a1dfa0c6 | 217 | |
e9174d1e SL |
218 | /// A closure can be modeled as a struct that looks like: |
219 | /// | |
ba9703b0 | 220 | /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U); |
e9174d1e | 221 | /// |
ff7c6d11 XL |
222 | /// where: |
223 | /// | |
ba9703b0 | 224 | /// - 'l0...'li and T0...Tj are the generic parameters |
ff7c6d11 XL |
225 | /// in scope on the function that defined the closure, |
226 | /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This | |
227 | /// is rather hackily encoded via a scalar type. See | |
228 | /// `TyS::to_opt_closure_kind` for details. | |
229 | /// - CS represents the *closure signature*, representing as a `fn()` | |
230 | /// type. For example, `fn(u32, u32) -> u32` would mean that the closure | |
231 | /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait | |
232 | /// specified above. | |
ba9703b0 XL |
233 | /// - U is a type parameter representing the types of its upvars, tupled up |
234 | /// (borrowed, if appropriate; that is, if an U field represents a by-ref upvar, | |
235 | /// and the up-var has the type `Foo`, then that field of U will be `&Foo`). | |
e9174d1e SL |
236 | /// |
237 | /// So, for example, given this function: | |
238 | /// | |
239 | /// fn foo<'a, T>(data: &'a mut T) { | |
240 | /// do(|| data.count += 1) | |
241 | /// } | |
242 | /// | |
243 | /// the type of the closure would be something like: | |
244 | /// | |
ba9703b0 | 245 | /// struct Closure<'a, T, U>(...U); |
e9174d1e SL |
246 | /// |
247 | /// Note that the type of the upvar is not specified in the struct. | |
248 | /// You may wonder how the impl would then be able to use the upvar, | |
249 | /// if it doesn't know it's type? The answer is that the impl is | |
250 | /// (conceptually) not fully generic over Closure but rather tied to | |
251 | /// instances with the expected upvar types: | |
252 | /// | |
ba9703b0 | 253 | /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> { |
e9174d1e SL |
254 | /// ... |
255 | /// } | |
256 | /// | |
257 | /// You can see that the *impl* fully specified the type of the upvar | |
258 | /// and thus knows full well that `data` has type `&'b mut &'a mut T`. | |
259 | /// (Here, I am assuming that `data` is mut-borrowed.) | |
260 | /// | |
261 | /// Now, the last question you may ask is: Why include the upvar types | |
ba9703b0 | 262 | /// in an extra type parameter? The reason for this design is that the |
e9174d1e SL |
263 | /// upvar types can reference lifetimes that are internal to the |
264 | /// creating function. In my example above, for example, the lifetime | |
ea8adc8c XL |
265 | /// `'b` represents the scope of the closure itself; this is some |
266 | /// subset of `foo`, probably just the scope of the call to the to | |
e9174d1e SL |
267 | /// `do()`. If we just had the lifetime/type parameters from the |
268 | /// enclosing function, we couldn't name this lifetime `'b`. Note that | |
269 | /// there can also be lifetimes in the types of the upvars themselves, | |
270 | /// if one of them happens to be a reference to something that the | |
271 | /// creating fn owns. | |
272 | /// | |
273 | /// OK, you say, so why not create a more minimal set of parameters | |
274 | /// that just includes the extra lifetime parameters? The answer is | |
275 | /// primarily that it would be hard --- we don't know at the time when | |
276 | /// we create the closure type what the full types of the upvars are, | |
277 | /// nor do we know which are borrowed and which are not. In this | |
278 | /// design, we can just supply a fresh type parameter and figure that | |
279 | /// out later. | |
280 | /// | |
281 | /// All right, you say, but why include the type parameters from the | |
94b46f34 | 282 | /// original function then? The answer is that codegen may need them |
9fa01778 | 283 | /// when monomorphizing, and they may not appear in the upvars. A |
e9174d1e SL |
284 | /// closure could capture no variables but still make use of some |
285 | /// in-scope type parameter with a bound (e.g., if our example above | |
286 | /// had an extra `U: Default`, and the closure called `U::default()`). | |
287 | /// | |
288 | /// There is another reason. This design (implicitly) prohibits | |
289 | /// closures from capturing themselves (except via a trait | |
290 | /// object). This simplifies closure inference considerably, since it | |
291 | /// means that when we infer the kind of a closure or its upvars, we | |
292 | /// don't have to handle cycles where the decisions we make for | |
293 | /// closure C wind up influencing the decisions we ought to make for | |
294 | /// closure C (which would then require fixed point iteration to | |
295 | /// handle). Plus it fixes an ICE. :P | |
ff7c6d11 XL |
296 | /// |
297 | /// ## Generators | |
298 | /// | |
48663c56 | 299 | /// Generators are handled similarly in `GeneratorSubsts`. The set of |
74b04a01 XL |
300 | /// type parameters is similar, but `CK` and `CS` are replaced by the |
301 | /// following type parameters: | |
302 | /// | |
303 | /// * `GS`: The generator's "resume type", which is the type of the | |
304 | /// argument passed to `resume`, and the type of `yield` expressions | |
305 | /// inside the generator. | |
306 | /// * `GY`: The "yield type", which is the type of values passed to | |
307 | /// `yield` inside the generator. | |
308 | /// * `GR`: The "return type", which is the type of value returned upon | |
309 | /// completion of the generator. | |
310 | /// * `GW`: The "generator witness". | |
60c5eb7d | 311 | #[derive(Copy, Clone, Debug, TypeFoldable)] |
e9174d1e | 312 | pub struct ClosureSubsts<'tcx> { |
476ff2be | 313 | /// Lifetime and type parameters from the enclosing function, |
ba9703b0 | 314 | /// concatenated with a tuple containing the types of the upvars. |
476ff2be | 315 | /// |
94b46f34 | 316 | /// These are separated out because codegen wants to pass them around |
e9174d1e | 317 | /// when monomorphizing. |
532ac7d7 | 318 | pub substs: SubstsRef<'tcx>, |
476ff2be | 319 | } |
e9174d1e | 320 | |
ff7c6d11 XL |
321 | /// Struct returned by `split()`. Note that these are subslices of the |
322 | /// parent slice and not canonical substs themselves. | |
323 | struct SplitClosureSubsts<'tcx> { | |
ba9703b0 XL |
324 | closure_kind_ty: GenericArg<'tcx>, |
325 | closure_sig_as_fn_ptr_ty: GenericArg<'tcx>, | |
326 | tupled_upvars_ty: GenericArg<'tcx>, | |
ff7c6d11 XL |
327 | } |
328 | ||
329 | impl<'tcx> ClosureSubsts<'tcx> { | |
330 | /// Divides the closure substs into their respective | |
331 | /// components. Single source of truth with respect to the | |
332 | /// ordering. | |
ba9703b0 XL |
333 | fn split(self) -> SplitClosureSubsts<'tcx> { |
334 | match self.substs[..] { | |
335 | [.., closure_kind_ty, closure_sig_as_fn_ptr_ty, tupled_upvars_ty] => { | |
336 | SplitClosureSubsts { closure_kind_ty, closure_sig_as_fn_ptr_ty, tupled_upvars_ty } | |
337 | } | |
338 | _ => bug!("closure substs missing synthetics"), | |
ff7c6d11 XL |
339 | } |
340 | } | |
341 | ||
ba9703b0 XL |
342 | /// Returns `true` only if enough of the synthetic types are known to |
343 | /// allow using all of the methods on `ClosureSubsts` without panicking. | |
344 | /// | |
345 | /// Used primarily by `ty::print::pretty` to be able to handle closure | |
346 | /// types that haven't had their synthetic types substituted in. | |
347 | pub fn is_valid(self) -> bool { | |
348 | self.substs.len() >= 3 && matches!(self.split().tupled_upvars_ty.expect_ty().kind, Tuple(_)) | |
349 | } | |
350 | ||
476ff2be | 351 | #[inline] |
ba9703b0 XL |
352 | pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx { |
353 | self.split().tupled_upvars_ty.expect_ty().tuple_fields() | |
ff7c6d11 XL |
354 | } |
355 | ||
356 | /// Returns the closure kind for this closure; may return a type | |
357 | /// variable during inference. To get the closure kind during | |
ba9703b0 XL |
358 | /// inference, use `infcx.closure_kind(substs)`. |
359 | pub fn kind_ty(self) -> Ty<'tcx> { | |
360 | self.split().closure_kind_ty.expect_ty() | |
ff7c6d11 XL |
361 | } |
362 | ||
ba9703b0 XL |
363 | /// Returns the `fn` pointer type representing the closure signature for this |
364 | /// closure. | |
365 | // FIXME(eddyb) this should be unnecessary, as the shallowly resolved | |
366 | // type is known at the time of the creation of `ClosureSubsts`, | |
367 | // see `rustc_typeck::check::closure`. | |
368 | pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> { | |
369 | self.split().closure_sig_as_fn_ptr_ty.expect_ty() | |
ff7c6d11 XL |
370 | } |
371 | ||
ff7c6d11 XL |
372 | /// Returns the closure kind for this closure; only usable outside |
373 | /// of an inference context, because in that context we know that | |
374 | /// there are no type variables. | |
375 | /// | |
376 | /// If you have an inference context, use `infcx.closure_kind()`. | |
ba9703b0 XL |
377 | pub fn kind(self) -> ty::ClosureKind { |
378 | self.kind_ty().to_opt_closure_kind().unwrap() | |
ff7c6d11 XL |
379 | } |
380 | ||
ba9703b0 XL |
381 | /// Extracts the signature from the closure. |
382 | pub fn sig(self) -> ty::PolyFnSig<'tcx> { | |
383 | let ty = self.sig_as_fn_ptr_ty(); | |
e74abb32 | 384 | match ty.kind { |
b7449926 | 385 | ty::FnPtr(sig) => sig, |
ba9703b0 | 386 | _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind), |
ff7c6d11 | 387 | } |
476ff2be | 388 | } |
a7813a04 | 389 | } |
9cc50fc6 | 390 | |
48663c56 | 391 | /// Similar to `ClosureSubsts`; see the above documentation for more. |
60c5eb7d | 392 | #[derive(Copy, Clone, Debug, TypeFoldable)] |
94b46f34 | 393 | pub struct GeneratorSubsts<'tcx> { |
532ac7d7 | 394 | pub substs: SubstsRef<'tcx>, |
94b46f34 XL |
395 | } |
396 | ||
397 | struct SplitGeneratorSubsts<'tcx> { | |
ba9703b0 XL |
398 | resume_ty: GenericArg<'tcx>, |
399 | yield_ty: GenericArg<'tcx>, | |
400 | return_ty: GenericArg<'tcx>, | |
401 | witness: GenericArg<'tcx>, | |
402 | tupled_upvars_ty: GenericArg<'tcx>, | |
94b46f34 XL |
403 | } |
404 | ||
405 | impl<'tcx> GeneratorSubsts<'tcx> { | |
ba9703b0 XL |
406 | fn split(self) -> SplitGeneratorSubsts<'tcx> { |
407 | match self.substs[..] { | |
408 | [.., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => { | |
409 | SplitGeneratorSubsts { resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty } | |
410 | } | |
411 | _ => bug!("generator substs missing synthetics"), | |
94b46f34 XL |
412 | } |
413 | } | |
414 | ||
ba9703b0 XL |
415 | /// Returns `true` only if enough of the synthetic types are known to |
416 | /// allow using all of the methods on `GeneratorSubsts` without panicking. | |
417 | /// | |
418 | /// Used primarily by `ty::print::pretty` to be able to handle generator | |
419 | /// types that haven't had their synthetic types substituted in. | |
420 | pub fn is_valid(self) -> bool { | |
421 | self.substs.len() >= 5 && matches!(self.split().tupled_upvars_ty.expect_ty().kind, Tuple(_)) | |
422 | } | |
423 | ||
94b46f34 XL |
424 | /// This describes the types that can be contained in a generator. |
425 | /// It will be a type variable initially and unified in the last stages of typeck of a body. | |
426 | /// It contains a tuple of all the types that could end up on a generator frame. | |
427 | /// The state transformation MIR pass may only produce layouts which mention types | |
428 | /// in this tuple. Upvars are not counted here. | |
ba9703b0 XL |
429 | pub fn witness(self) -> Ty<'tcx> { |
430 | self.split().witness.expect_ty() | |
94b46f34 XL |
431 | } |
432 | ||
433 | #[inline] | |
ba9703b0 XL |
434 | pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx { |
435 | self.split().tupled_upvars_ty.expect_ty().tuple_fields() | |
94b46f34 XL |
436 | } |
437 | ||
74b04a01 | 438 | /// Returns the type representing the resume type of the generator. |
ba9703b0 XL |
439 | pub fn resume_ty(self) -> Ty<'tcx> { |
440 | self.split().resume_ty.expect_ty() | |
74b04a01 XL |
441 | } |
442 | ||
94b46f34 | 443 | /// Returns the type representing the yield type of the generator. |
ba9703b0 XL |
444 | pub fn yield_ty(self) -> Ty<'tcx> { |
445 | self.split().yield_ty.expect_ty() | |
94b46f34 XL |
446 | } |
447 | ||
448 | /// Returns the type representing the return type of the generator. | |
ba9703b0 XL |
449 | pub fn return_ty(self) -> Ty<'tcx> { |
450 | self.split().return_ty.expect_ty() | |
94b46f34 XL |
451 | } |
452 | ||
9fa01778 | 453 | /// Returns the "generator signature", which consists of its yield |
94b46f34 XL |
454 | /// and return types. |
455 | /// | |
9fa01778 | 456 | /// N.B., some bits of the code prefers to see this wrapped in a |
94b46f34 XL |
457 | /// binder, but it never contains bound regions. Probably this |
458 | /// function should be removed. | |
ba9703b0 XL |
459 | pub fn poly_sig(self) -> PolyGenSig<'tcx> { |
460 | ty::Binder::dummy(self.sig()) | |
94b46f34 XL |
461 | } |
462 | ||
74b04a01 | 463 | /// Returns the "generator signature", which consists of its resume, yield |
94b46f34 | 464 | /// and return types. |
ba9703b0 | 465 | pub fn sig(self) -> GenSig<'tcx> { |
74b04a01 | 466 | ty::GenSig { |
ba9703b0 XL |
467 | resume_ty: self.resume_ty(), |
468 | yield_ty: self.yield_ty(), | |
469 | return_ty: self.return_ty(), | |
74b04a01 | 470 | } |
94b46f34 XL |
471 | } |
472 | } | |
473 | ||
dc9dc135 | 474 | impl<'tcx> GeneratorSubsts<'tcx> { |
60c5eb7d | 475 | /// Generator has not been resumed yet. |
48663c56 | 476 | pub const UNRESUMED: usize = 0; |
60c5eb7d | 477 | /// Generator has returned or is completed. |
48663c56 | 478 | pub const RETURNED: usize = 1; |
60c5eb7d | 479 | /// Generator has been poisoned. |
48663c56 XL |
480 | pub const POISONED: usize = 2; |
481 | ||
482 | const UNRESUMED_NAME: &'static str = "Unresumed"; | |
483 | const RETURNED_NAME: &'static str = "Returned"; | |
484 | const POISONED_NAME: &'static str = "Panicked"; | |
485 | ||
60c5eb7d | 486 | /// The valid variant indices of this generator. |
48663c56 | 487 | #[inline] |
dc9dc135 | 488 | pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> { |
48663c56 XL |
489 | // FIXME requires optimized MIR |
490 | let num_variants = tcx.generator_layout(def_id).variant_fields.len(); | |
dfeec247 | 491 | VariantIdx::new(0)..VariantIdx::new(num_variants) |
48663c56 XL |
492 | } |
493 | ||
60c5eb7d | 494 | /// The discriminant for the given variant. Panics if the `variant_index` is |
48663c56 XL |
495 | /// out of range. |
496 | #[inline] | |
497 | pub fn discriminant_for_variant( | |
dc9dc135 XL |
498 | &self, |
499 | def_id: DefId, | |
500 | tcx: TyCtxt<'tcx>, | |
501 | variant_index: VariantIdx, | |
48663c56 XL |
502 | ) -> Discr<'tcx> { |
503 | // Generators don't support explicit discriminant values, so they are | |
504 | // the same as the variant index. | |
505 | assert!(self.variant_range(def_id, tcx).contains(&variant_index)); | |
506 | Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) } | |
507 | } | |
508 | ||
60c5eb7d | 509 | /// The set of all discriminants for the generator, enumerated with their |
48663c56 XL |
510 | /// variant indices. |
511 | #[inline] | |
512 | pub fn discriminants( | |
e74abb32 | 513 | self, |
dc9dc135 XL |
514 | def_id: DefId, |
515 | tcx: TyCtxt<'tcx>, | |
516 | ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> { | |
48663c56 XL |
517 | self.variant_range(def_id, tcx).map(move |index| { |
518 | (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) }) | |
519 | }) | |
520 | } | |
521 | ||
522 | /// Calls `f` with a reference to the name of the enumerator for the given | |
523 | /// variant `v`. | |
524 | #[inline] | |
e74abb32 | 525 | pub fn variant_name(self, v: VariantIdx) -> Cow<'static, str> { |
48663c56 XL |
526 | match v.as_usize() { |
527 | Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME), | |
528 | Self::RETURNED => Cow::from(Self::RETURNED_NAME), | |
529 | Self::POISONED => Cow::from(Self::POISONED_NAME), | |
dfeec247 | 530 | _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)), |
48663c56 XL |
531 | } |
532 | } | |
533 | ||
534 | /// The type of the state discriminant used in the generator type. | |
535 | #[inline] | |
dc9dc135 | 536 | pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { |
48663c56 XL |
537 | tcx.types.u32 |
538 | } | |
539 | ||
ea8adc8c XL |
540 | /// This returns the types of the MIR locals which had to be stored across suspension points. |
541 | /// It is calculated in rustc_mir::transform::generator::StateTransform. | |
542 | /// All the types here must be in the tuple in GeneratorInterior. | |
48663c56 XL |
543 | /// |
544 | /// The locals are grouped by their variant number. Note that some locals may | |
545 | /// be repeated in multiple variants. | |
546 | #[inline] | |
dc9dc135 XL |
547 | pub fn state_tys( |
548 | self, | |
549 | def_id: DefId, | |
550 | tcx: TyCtxt<'tcx>, | |
551 | ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> { | |
48663c56 XL |
552 | let layout = tcx.generator_layout(def_id); |
553 | layout.variant_fields.iter().map(move |variant| { | |
dfeec247 | 554 | variant.iter().map(move |field| layout.field_tys[*field].subst(tcx, self.substs)) |
48663c56 | 555 | }) |
2c00a5a8 XL |
556 | } |
557 | ||
48663c56 XL |
558 | /// This is the types of the fields of a generator which are not stored in a |
559 | /// variant. | |
560 | #[inline] | |
ba9703b0 XL |
561 | pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> { |
562 | self.upvar_tys() | |
ea8adc8c XL |
563 | } |
564 | } | |
565 | ||
94b46f34 XL |
566 | #[derive(Debug, Copy, Clone)] |
567 | pub enum UpvarSubsts<'tcx> { | |
e74abb32 XL |
568 | Closure(SubstsRef<'tcx>), |
569 | Generator(SubstsRef<'tcx>), | |
94b46f34 XL |
570 | } |
571 | ||
572 | impl<'tcx> UpvarSubsts<'tcx> { | |
573 | #[inline] | |
ba9703b0 XL |
574 | pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx { |
575 | let tupled_upvars_ty = match self { | |
576 | UpvarSubsts::Closure(substs) => substs.as_closure().split().tupled_upvars_ty, | |
577 | UpvarSubsts::Generator(substs) => substs.as_generator().split().tupled_upvars_ty, | |
94b46f34 | 578 | }; |
ba9703b0 | 579 | tupled_upvars_ty.expect_ty().tuple_fields() |
94b46f34 | 580 | } |
ea8adc8c XL |
581 | } |
582 | ||
60c5eb7d XL |
583 | #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, RustcEncodable, RustcDecodable)] |
584 | #[derive(HashStable, TypeFoldable)] | |
476ff2be | 585 | pub enum ExistentialPredicate<'tcx> { |
9fa01778 | 586 | /// E.g., `Iterator`. |
476ff2be | 587 | Trait(ExistentialTraitRef<'tcx>), |
9fa01778 | 588 | /// E.g., `Iterator::Item = T`. |
476ff2be | 589 | Projection(ExistentialProjection<'tcx>), |
9fa01778 | 590 | /// E.g., `Send`. |
476ff2be SL |
591 | AutoTrait(DefId), |
592 | } | |
593 | ||
dc9dc135 | 594 | impl<'tcx> ExistentialPredicate<'tcx> { |
94b46f34 XL |
595 | /// Compares via an ordering that will not change if modules are reordered or other changes are |
596 | /// made to the tree. In particular, this ordering is preserved across incremental compilations. | |
dc9dc135 | 597 | pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering { |
476ff2be SL |
598 | use self::ExistentialPredicate::*; |
599 | match (*self, *other) { | |
600 | (Trait(_), Trait(_)) => Ordering::Equal, | |
dfeec247 XL |
601 | (Projection(ref a), Projection(ref b)) => { |
602 | tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)) | |
603 | } | |
604 | (AutoTrait(ref a), AutoTrait(ref b)) => { | |
605 | tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash) | |
606 | } | |
476ff2be SL |
607 | (Trait(_), _) => Ordering::Less, |
608 | (Projection(_), Trait(_)) => Ordering::Greater, | |
609 | (Projection(_), _) => Ordering::Less, | |
610 | (AutoTrait(_), _) => Ordering::Greater, | |
611 | } | |
612 | } | |
476ff2be SL |
613 | } |
614 | ||
dc9dc135 XL |
615 | impl<'tcx> Binder<ExistentialPredicate<'tcx>> { |
616 | pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> { | |
9fa01778 | 617 | use crate::ty::ToPredicate; |
476ff2be | 618 | match *self.skip_binder() { |
dfeec247 XL |
619 | ExistentialPredicate::Trait(tr) => { |
620 | Binder(tr).with_self_ty(tcx, self_ty).without_const().to_predicate() | |
621 | } | |
622 | ExistentialPredicate::Projection(p) => { | |
623 | ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))) | |
624 | } | |
476ff2be | 625 | ExistentialPredicate::AutoTrait(did) => { |
dfeec247 XL |
626 | let trait_ref = |
627 | Binder(ty::TraitRef { def_id: did, substs: tcx.mk_substs_trait(self_ty, &[]) }); | |
628 | trait_ref.without_const().to_predicate() | |
476ff2be SL |
629 | } |
630 | } | |
631 | } | |
632 | } | |
633 | ||
416331ca | 634 | impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {} |
476ff2be | 635 | |
b7449926 | 636 | impl<'tcx> List<ExistentialPredicate<'tcx>> { |
e1599b0c | 637 | /// Returns the "principal `DefId`" of this set of existential predicates. |
0731742a XL |
638 | /// |
639 | /// A Rust trait object type consists (in addition to a lifetime bound) | |
640 | /// of a set of trait bounds, which are separated into any number | |
416331ca | 641 | /// of auto-trait bounds, and at most one non-auto-trait bound. The |
0731742a XL |
642 | /// non-auto-trait bound is called the "principal" of the trait |
643 | /// object. | |
644 | /// | |
645 | /// Only the principal can have methods or type parameters (because | |
646 | /// auto traits can have neither of them). This is important, because | |
647 | /// it means the auto traits can be treated as an unordered set (methods | |
648 | /// would force an order for the vtable, while relating traits with | |
649 | /// type parameters without knowing the order to relate them in is | |
650 | /// a rather non-trivial task). | |
651 | /// | |
652 | /// For example, in the trait object `dyn fmt::Debug + Sync`, the | |
653 | /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds | |
654 | /// are the set `{Sync}`. | |
655 | /// | |
656 | /// It is also possible to have a "trivial" trait object that | |
657 | /// consists only of auto traits, with no principal - for example, | |
658 | /// `dyn Send + Sync`. In that case, the set of auto-trait bounds | |
659 | /// is `{Send, Sync}`, while there is no principal. These trait objects | |
660 | /// have a "trivial" vtable consisting of just the size, alignment, | |
661 | /// and destructor. | |
662 | pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> { | |
0bf4aa26 | 663 | match self[0] { |
0731742a | 664 | ExistentialPredicate::Trait(tr) => Some(tr), |
60c5eb7d | 665 | _ => None, |
476ff2be SL |
666 | } |
667 | } | |
668 | ||
0731742a | 669 | pub fn principal_def_id(&self) -> Option<DefId> { |
60c5eb7d | 670 | self.principal().map(|trait_ref| trait_ref.def_id) |
0731742a XL |
671 | } |
672 | ||
476ff2be | 673 | #[inline] |
dfeec247 XL |
674 | pub fn projection_bounds<'a>( |
675 | &'a self, | |
676 | ) -> impl Iterator<Item = ExistentialProjection<'tcx>> + 'a { | |
677 | self.iter().filter_map(|predicate| match *predicate { | |
678 | ExistentialPredicate::Projection(projection) => Some(projection), | |
679 | _ => None, | |
476ff2be SL |
680 | }) |
681 | } | |
682 | ||
683 | #[inline] | |
416331ca | 684 | pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a { |
dfeec247 XL |
685 | self.iter().filter_map(|predicate| match *predicate { |
686 | ExistentialPredicate::AutoTrait(did) => Some(did), | |
687 | _ => None, | |
476ff2be SL |
688 | }) |
689 | } | |
690 | } | |
691 | ||
b7449926 | 692 | impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> { |
0731742a XL |
693 | pub fn principal(&self) -> Option<ty::Binder<ExistentialTraitRef<'tcx>>> { |
694 | self.skip_binder().principal().map(Binder::bind) | |
695 | } | |
696 | ||
697 | pub fn principal_def_id(&self) -> Option<DefId> { | |
698 | self.skip_binder().principal_def_id() | |
476ff2be SL |
699 | } |
700 | ||
701 | #[inline] | |
dfeec247 XL |
702 | pub fn projection_bounds<'a>( |
703 | &'a self, | |
704 | ) -> impl Iterator<Item = PolyExistentialProjection<'tcx>> + 'a { | |
83c7162d | 705 | self.skip_binder().projection_bounds().map(Binder::bind) |
476ff2be SL |
706 | } |
707 | ||
708 | #[inline] | |
416331ca | 709 | pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a { |
476ff2be SL |
710 | self.skip_binder().auto_traits() |
711 | } | |
712 | ||
dfeec247 XL |
713 | pub fn iter<'a>( |
714 | &'a self, | |
715 | ) -> impl DoubleEndedIterator<Item = Binder<ExistentialPredicate<'tcx>>> + 'tcx { | |
83c7162d | 716 | self.skip_binder().iter().cloned().map(Binder::bind) |
476ff2be | 717 | } |
e9174d1e SL |
718 | } |
719 | ||
720 | /// A complete reference to a trait. These take numerous guises in syntax, | |
9fa01778 | 721 | /// but perhaps the most recognizable form is in a where-clause: |
e9174d1e | 722 | /// |
a1dfa0c6 | 723 | /// T: Foo<U> |
e9174d1e | 724 | /// |
9fa01778 XL |
725 | /// This would be represented by a trait-reference where the `DefId` is the |
726 | /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0, | |
9e0c209e | 727 | /// and `U` as parameter 1. |
e9174d1e SL |
728 | /// |
729 | /// Trait references also appear in object types like `Foo<U>`, but in | |
730 | /// that case the `Self` parameter is absent from the substitutions. | |
731 | /// | |
732 | /// Note that a `TraitRef` introduces a level of region binding, to | |
a1dfa0c6 XL |
733 | /// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>` |
734 | /// or higher-ranked object types. | |
60c5eb7d XL |
735 | #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)] |
736 | #[derive(HashStable, TypeFoldable)] | |
e9174d1e SL |
737 | pub struct TraitRef<'tcx> { |
738 | pub def_id: DefId, | |
532ac7d7 | 739 | pub substs: SubstsRef<'tcx>, |
e9174d1e SL |
740 | } |
741 | ||
8bb4bdeb | 742 | impl<'tcx> TraitRef<'tcx> { |
532ac7d7 | 743 | pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> { |
60c5eb7d | 744 | TraitRef { def_id, substs } |
8bb4bdeb XL |
745 | } |
746 | ||
a1dfa0c6 | 747 | /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi` |
8faf50e0 | 748 | /// are the parameters defined on trait. |
dc9dc135 | 749 | pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> TraitRef<'tcx> { |
dfeec247 | 750 | TraitRef { def_id, substs: InternalSubsts::identity_for_item(tcx, def_id) } |
8faf50e0 XL |
751 | } |
752 | ||
a1dfa0c6 | 753 | #[inline] |
8bb4bdeb XL |
754 | pub fn self_ty(&self) -> Ty<'tcx> { |
755 | self.substs.type_at(0) | |
756 | } | |
757 | ||
dc9dc135 XL |
758 | pub fn from_method( |
759 | tcx: TyCtxt<'tcx>, | |
760 | trait_id: DefId, | |
761 | substs: SubstsRef<'tcx>, | |
762 | ) -> ty::TraitRef<'tcx> { | |
94b46f34 XL |
763 | let defs = tcx.generics_of(trait_id); |
764 | ||
dfeec247 | 765 | ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) } |
94b46f34 | 766 | } |
8bb4bdeb XL |
767 | } |
768 | ||
e9174d1e SL |
769 | pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>; |
770 | ||
771 | impl<'tcx> PolyTraitRef<'tcx> { | |
772 | pub fn self_ty(&self) -> Ty<'tcx> { | |
83c7162d | 773 | self.skip_binder().self_ty() |
e9174d1e SL |
774 | } |
775 | ||
776 | pub fn def_id(&self) -> DefId { | |
83c7162d | 777 | self.skip_binder().def_id |
e9174d1e SL |
778 | } |
779 | ||
780 | pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> { | |
781 | // Note that we preserve binding levels | |
dfeec247 | 782 | Binder(ty::TraitPredicate { trait_ref: *self.skip_binder() }) |
e9174d1e SL |
783 | } |
784 | } | |
785 | ||
9e0c209e SL |
786 | /// An existential reference to a trait, where `Self` is erased. |
787 | /// For example, the trait object `Trait<'a, 'b, X, Y>` is: | |
788 | /// | |
789 | /// exists T. T: Trait<'a, 'b, X, Y> | |
790 | /// | |
791 | /// The substitutions don't include the erased `Self`, only trait | |
792 | /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above). | |
60c5eb7d XL |
793 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
794 | #[derive(HashStable, TypeFoldable)] | |
9e0c209e SL |
795 | pub struct ExistentialTraitRef<'tcx> { |
796 | pub def_id: DefId, | |
532ac7d7 | 797 | pub substs: SubstsRef<'tcx>, |
9e0c209e SL |
798 | } |
799 | ||
dc9dc135 | 800 | impl<'tcx> ExistentialTraitRef<'tcx> { |
dc9dc135 XL |
801 | pub fn erase_self_ty( |
802 | tcx: TyCtxt<'tcx>, | |
803 | trait_ref: ty::TraitRef<'tcx>, | |
804 | ) -> ty::ExistentialTraitRef<'tcx> { | |
94b46f34 XL |
805 | // Assert there is a Self. |
806 | trait_ref.substs.type_at(0); | |
807 | ||
808 | ty::ExistentialTraitRef { | |
809 | def_id: trait_ref.def_id, | |
dfeec247 | 810 | substs: tcx.intern_substs(&trait_ref.substs[1..]), |
94b46f34 XL |
811 | } |
812 | } | |
813 | ||
9fa01778 | 814 | /// Object types don't have a self type specified. Therefore, when |
476ff2be | 815 | /// we convert the principal trait-ref into a normal trait-ref, |
9fa01778 | 816 | /// you must give *some* self type. A common choice is `mk_err()` |
0bf4aa26 | 817 | /// or some placeholder type. |
dc9dc135 | 818 | pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> { |
a1dfa0c6 XL |
819 | // otherwise the escaping vars would be captured by the binder |
820 | // debug_assert!(!self_ty.has_escaping_bound_vars()); | |
476ff2be | 821 | |
dfeec247 | 822 | ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) } |
476ff2be | 823 | } |
9e0c209e SL |
824 | } |
825 | ||
826 | pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>; | |
827 | ||
828 | impl<'tcx> PolyExistentialTraitRef<'tcx> { | |
829 | pub fn def_id(&self) -> DefId { | |
83c7162d | 830 | self.skip_binder().def_id |
9e0c209e | 831 | } |
94b46f34 | 832 | |
9fa01778 | 833 | /// Object types don't have a self type specified. Therefore, when |
94b46f34 | 834 | /// we convert the principal trait-ref into a normal trait-ref, |
9fa01778 | 835 | /// you must give *some* self type. A common choice is `mk_err()` |
0bf4aa26 | 836 | /// or some placeholder type. |
dc9dc135 | 837 | pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> { |
94b46f34 XL |
838 | self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty)) |
839 | } | |
9e0c209e SL |
840 | } |
841 | ||
a1dfa0c6 | 842 | /// Binder is a binder for higher-ranked lifetimes or types. It is part of the |
e9174d1e SL |
843 | /// compiler's representation for things like `for<'a> Fn(&'a isize)` |
844 | /// (which would be represented by the type `PolyTraitRef == | |
0bf4aa26 | 845 | /// Binder<TraitRef>`). Note that when we instantiate, |
a1dfa0c6 | 846 | /// erase, or otherwise "discharge" these bound vars, we change the |
e9174d1e | 847 | /// type from `Binder<T>` to just `T` (see |
0731742a | 848 | /// e.g., `liberate_late_bound_regions`). |
94b46f34 | 849 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
83c7162d | 850 | pub struct Binder<T>(T); |
e9174d1e SL |
851 | |
852 | impl<T> Binder<T> { | |
ff7c6d11 | 853 | /// Wraps `value` in a binder, asserting that `value` does not |
a1dfa0c6 | 854 | /// contain any bound vars that would be bound by the |
ff7c6d11 XL |
855 | /// binder. This is commonly used to 'inject' a value T into a |
856 | /// different binding level. | |
857 | pub fn dummy<'tcx>(value: T) -> Binder<T> | |
dfeec247 XL |
858 | where |
859 | T: TypeFoldable<'tcx>, | |
ff7c6d11 | 860 | { |
a1dfa0c6 | 861 | debug_assert!(!value.has_escaping_bound_vars()); |
ff7c6d11 XL |
862 | Binder(value) |
863 | } | |
864 | ||
a1dfa0c6 | 865 | /// Wraps `value` in a binder, binding higher-ranked vars (if any). |
dc9dc135 | 866 | pub fn bind(value: T) -> Binder<T> { |
83c7162d XL |
867 | Binder(value) |
868 | } | |
869 | ||
e9174d1e SL |
870 | /// Skips the binder and returns the "bound" value. This is a |
871 | /// risky thing to do because it's easy to get confused about | |
9fa01778 | 872 | /// De Bruijn indices and the like. It is usually better to |
a1dfa0c6 | 873 | /// discharge the binder using `no_bound_vars` or |
e9174d1e SL |
874 | /// `replace_late_bound_regions` or something like |
875 | /// that. `skip_binder` is only valid when you are either | |
a1dfa0c6 | 876 | /// extracting data that has nothing to do with bound vars, you |
e9174d1e SL |
877 | /// are doing some sort of test that does not involve bound |
878 | /// regions, or you are being very careful about your depth | |
879 | /// accounting. | |
880 | /// | |
881 | /// Some examples where `skip_binder` is reasonable: | |
ff7c6d11 | 882 | /// |
9fa01778 | 883 | /// - extracting the `DefId` from a PolyTraitRef; |
e9174d1e | 884 | /// - comparing the self type of a PolyTraitRef to see if it is equal to |
a1dfa0c6 | 885 | /// a type parameter `X`, since the type `X` does not reference any regions |
e9174d1e SL |
886 | pub fn skip_binder(&self) -> &T { |
887 | &self.0 | |
888 | } | |
889 | ||
890 | pub fn as_ref(&self) -> Binder<&T> { | |
83c7162d | 891 | Binder(&self.0) |
e9174d1e SL |
892 | } |
893 | ||
cc61c64b | 894 | pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U> |
dfeec247 XL |
895 | where |
896 | F: FnOnce(&T) -> U, | |
e9174d1e SL |
897 | { |
898 | self.as_ref().map_bound(f) | |
899 | } | |
900 | ||
cc61c64b | 901 | pub fn map_bound<F, U>(self, f: F) -> Binder<U> |
dfeec247 XL |
902 | where |
903 | F: FnOnce(T) -> U, | |
e9174d1e | 904 | { |
83c7162d | 905 | Binder(f(self.0)) |
e9174d1e | 906 | } |
ff7c6d11 XL |
907 | |
908 | /// Unwraps and returns the value within, but only if it contains | |
a1dfa0c6 | 909 | /// no bound vars at all. (In other words, if this binder -- |
ff7c6d11 XL |
910 | /// and indeed any enclosing binder -- doesn't bind anything at |
911 | /// all.) Otherwise, returns `None`. | |
912 | /// | |
913 | /// (One could imagine having a method that just unwraps a single | |
a1dfa0c6 | 914 | /// binder, but permits late-bound vars bound by enclosing |
ff7c6d11 XL |
915 | /// binders, but that would require adjusting the debruijn |
916 | /// indices, and given the shallow binding structure we often use, | |
917 | /// would not be that useful.) | |
a1dfa0c6 | 918 | pub fn no_bound_vars<'tcx>(self) -> Option<T> |
dfeec247 XL |
919 | where |
920 | T: TypeFoldable<'tcx>, | |
ff7c6d11 | 921 | { |
a1dfa0c6 | 922 | if self.skip_binder().has_escaping_bound_vars() { |
ff7c6d11 XL |
923 | None |
924 | } else { | |
925 | Some(self.skip_binder().clone()) | |
926 | } | |
927 | } | |
928 | ||
929 | /// Given two things that have the same binder level, | |
9fa01778 XL |
930 | /// and an operation that wraps on their contents, executes the operation |
931 | /// and then wraps its result. | |
ff7c6d11 XL |
932 | /// |
933 | /// `f` should consider bound regions at depth 1 to be free, and | |
934 | /// anything it produces with bound regions at depth 1 will be | |
935 | /// bound in the resulting return value. | |
dfeec247 XL |
936 | pub fn fuse<U, F, R>(self, u: Binder<U>, f: F) -> Binder<R> |
937 | where | |
938 | F: FnOnce(T, U) -> R, | |
ff7c6d11 | 939 | { |
83c7162d | 940 | Binder(f(self.0, u.0)) |
ff7c6d11 XL |
941 | } |
942 | ||
9fa01778 | 943 | /// Splits the contents into two things that share the same binder |
ff7c6d11 XL |
944 | /// level as the original, returning two distinct binders. |
945 | /// | |
946 | /// `f` should consider bound regions at depth 1 to be free, and | |
947 | /// anything it produces with bound regions at depth 1 will be | |
948 | /// bound in the resulting return values. | |
dfeec247 XL |
949 | pub fn split<U, V, F>(self, f: F) -> (Binder<U>, Binder<V>) |
950 | where | |
951 | F: FnOnce(T) -> (U, V), | |
ff7c6d11 XL |
952 | { |
953 | let (u, v) = f(self.0); | |
83c7162d | 954 | (Binder(u), Binder(v)) |
ff7c6d11 | 955 | } |
e9174d1e SL |
956 | } |
957 | ||
e9174d1e SL |
958 | /// Represents the projection of an associated type. In explicit UFCS |
959 | /// form this would be written `<T as Trait<..>>::N`. | |
60c5eb7d XL |
960 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
961 | #[derive(HashStable, TypeFoldable)] | |
e9174d1e | 962 | pub struct ProjectionTy<'tcx> { |
041b39d2 | 963 | /// The parameters of the associated item. |
532ac7d7 | 964 | pub substs: SubstsRef<'tcx>, |
e9174d1e | 965 | |
a1dfa0c6 | 966 | /// The `DefId` of the `TraitItem` for the associated type `N`. |
7cac9316 | 967 | /// |
a1dfa0c6 XL |
968 | /// Note that this is not the `DefId` of the `TraitRef` containing this |
969 | /// associated type, which is in `tcx.associated_item(item_def_id).container`. | |
7cac9316 | 970 | pub item_def_id: DefId, |
e9174d1e | 971 | } |
7cac9316 | 972 | |
dc9dc135 | 973 | impl<'tcx> ProjectionTy<'tcx> { |
a1dfa0c6 XL |
974 | /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the |
975 | /// associated item named `item_name`. | |
7cac9316 | 976 | pub fn from_ref_and_name( |
dc9dc135 XL |
977 | tcx: TyCtxt<'_>, |
978 | trait_ref: ty::TraitRef<'tcx>, | |
979 | item_name: Ident, | |
7cac9316 | 980 | ) -> ProjectionTy<'tcx> { |
dfeec247 XL |
981 | let item_def_id = tcx |
982 | .associated_items(trait_ref.def_id) | |
74b04a01 | 983 | .find_by_name_and_kind(tcx, item_name, ty::AssocKind::Type, trait_ref.def_id) |
dfeec247 XL |
984 | .unwrap() |
985 | .def_id; | |
7cac9316 | 986 | |
dfeec247 | 987 | ProjectionTy { substs: trait_ref.substs, item_def_id } |
7cac9316 XL |
988 | } |
989 | ||
041b39d2 XL |
990 | /// Extracts the underlying trait reference from this projection. |
991 | /// For example, if this is a projection of `<T as Iterator>::Item`, | |
992 | /// then this function would return a `T: Iterator` trait reference. | |
dfeec247 | 993 | pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> { |
041b39d2 | 994 | let def_id = tcx.associated_item(self.item_def_id).container.id(); |
dfeec247 | 995 | ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) } |
041b39d2 XL |
996 | } |
997 | ||
998 | pub fn self_ty(&self) -> Ty<'tcx> { | |
999 | self.substs.type_at(0) | |
7cac9316 XL |
1000 | } |
1001 | } | |
1002 | ||
60c5eb7d | 1003 | #[derive(Clone, Debug, TypeFoldable)] |
ea8adc8c | 1004 | pub struct GenSig<'tcx> { |
74b04a01 | 1005 | pub resume_ty: Ty<'tcx>, |
ea8adc8c XL |
1006 | pub yield_ty: Ty<'tcx>, |
1007 | pub return_ty: Ty<'tcx>, | |
1008 | } | |
1009 | ||
1010 | pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>; | |
1011 | ||
1012 | impl<'tcx> PolyGenSig<'tcx> { | |
74b04a01 XL |
1013 | pub fn resume_ty(&self) -> ty::Binder<Ty<'tcx>> { |
1014 | self.map_bound_ref(|sig| sig.resume_ty) | |
1015 | } | |
ea8adc8c XL |
1016 | pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> { |
1017 | self.map_bound_ref(|sig| sig.yield_ty) | |
1018 | } | |
1019 | pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> { | |
1020 | self.map_bound_ref(|sig| sig.return_ty) | |
1021 | } | |
1022 | } | |
7cac9316 | 1023 | |
e1599b0c | 1024 | /// Signature of a function type, which we have arbitrarily |
e9174d1e SL |
1025 | /// decided to use to refer to the input/output types. |
1026 | /// | |
532ac7d7 XL |
1027 | /// - `inputs`: is the list of arguments and their modes. |
1028 | /// - `output`: is the return type. | |
1029 | /// - `c_variadic`: indicates whether this is a C-variadic function. | |
60c5eb7d XL |
1030 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
1031 | #[derive(HashStable, TypeFoldable)] | |
e9174d1e | 1032 | pub struct FnSig<'tcx> { |
b7449926 | 1033 | pub inputs_and_output: &'tcx List<Ty<'tcx>>, |
532ac7d7 | 1034 | pub c_variadic: bool, |
8bb4bdeb XL |
1035 | pub unsafety: hir::Unsafety, |
1036 | pub abi: abi::Abi, | |
e9174d1e SL |
1037 | } |
1038 | ||
476ff2be | 1039 | impl<'tcx> FnSig<'tcx> { |
8bb4bdeb | 1040 | pub fn inputs(&self) -> &'tcx [Ty<'tcx>] { |
476ff2be SL |
1041 | &self.inputs_and_output[..self.inputs_and_output.len() - 1] |
1042 | } | |
1043 | ||
1044 | pub fn output(&self) -> Ty<'tcx> { | |
1045 | self.inputs_and_output[self.inputs_and_output.len() - 1] | |
1046 | } | |
48663c56 | 1047 | |
e1599b0c XL |
1048 | // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible |
1049 | // method. | |
48663c56 XL |
1050 | fn fake() -> FnSig<'tcx> { |
1051 | FnSig { | |
1052 | inputs_and_output: List::empty(), | |
1053 | c_variadic: false, | |
1054 | unsafety: hir::Unsafety::Normal, | |
1055 | abi: abi::Abi::Rust, | |
1056 | } | |
1057 | } | |
476ff2be SL |
1058 | } |
1059 | ||
e9174d1e SL |
1060 | pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>; |
1061 | ||
1062 | impl<'tcx> PolyFnSig<'tcx> { | |
a1dfa0c6 | 1063 | #[inline] |
8bb4bdeb | 1064 | pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> { |
83c7162d | 1065 | self.map_bound_ref(|fn_sig| fn_sig.inputs()) |
e9174d1e | 1066 | } |
a1dfa0c6 | 1067 | #[inline] |
e9174d1e | 1068 | pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> { |
476ff2be | 1069 | self.map_bound_ref(|fn_sig| fn_sig.inputs()[index]) |
e9174d1e | 1070 | } |
b7449926 | 1071 | pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> { |
ff7c6d11 XL |
1072 | self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output) |
1073 | } | |
a1dfa0c6 | 1074 | #[inline] |
5bcae85e | 1075 | pub fn output(&self) -> ty::Binder<Ty<'tcx>> { |
0bf4aa26 | 1076 | self.map_bound_ref(|fn_sig| fn_sig.output()) |
e9174d1e | 1077 | } |
532ac7d7 XL |
1078 | pub fn c_variadic(&self) -> bool { |
1079 | self.skip_binder().c_variadic | |
e9174d1e | 1080 | } |
8bb4bdeb XL |
1081 | pub fn unsafety(&self) -> hir::Unsafety { |
1082 | self.skip_binder().unsafety | |
1083 | } | |
1084 | pub fn abi(&self) -> abi::Abi { | |
1085 | self.skip_binder().abi | |
1086 | } | |
e9174d1e SL |
1087 | } |
1088 | ||
0bf4aa26 XL |
1089 | pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>; |
1090 | ||
ba9703b0 XL |
1091 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
1092 | #[derive(HashStable)] | |
e9174d1e | 1093 | pub struct ParamTy { |
48663c56 | 1094 | pub index: u32, |
e74abb32 | 1095 | pub name: Symbol, |
e9174d1e SL |
1096 | } |
1097 | ||
dc9dc135 | 1098 | impl<'tcx> ParamTy { |
e74abb32 | 1099 | pub fn new(index: u32, name: Symbol) -> ParamTy { |
74b04a01 | 1100 | ParamTy { index, name } |
e9174d1e SL |
1101 | } |
1102 | ||
1103 | pub fn for_self() -> ParamTy { | |
e74abb32 | 1104 | ParamTy::new(0, kw::SelfUpper) |
e9174d1e SL |
1105 | } |
1106 | ||
94b46f34 | 1107 | pub fn for_def(def: &ty::GenericParamDef) -> ParamTy { |
9e0c209e | 1108 | ParamTy::new(def.index, def.name) |
e9174d1e SL |
1109 | } |
1110 | ||
dc9dc135 | 1111 | pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { |
48663c56 | 1112 | tcx.mk_ty_param(self.index, self.name) |
e9174d1e | 1113 | } |
e9174d1e SL |
1114 | } |
1115 | ||
ba9703b0 XL |
1116 | #[derive(Copy, Clone, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)] |
1117 | #[derive(HashStable)] | |
532ac7d7 XL |
1118 | pub struct ParamConst { |
1119 | pub index: u32, | |
e74abb32 | 1120 | pub name: Symbol, |
532ac7d7 XL |
1121 | } |
1122 | ||
dc9dc135 | 1123 | impl<'tcx> ParamConst { |
e74abb32 | 1124 | pub fn new(index: u32, name: Symbol) -> ParamConst { |
532ac7d7 XL |
1125 | ParamConst { index, name } |
1126 | } | |
1127 | ||
1128 | pub fn for_def(def: &ty::GenericParamDef) -> ParamConst { | |
1129 | ParamConst::new(def.index, def.name) | |
1130 | } | |
1131 | ||
dc9dc135 | 1132 | pub fn to_const(self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Const<'tcx> { |
532ac7d7 XL |
1133 | tcx.mk_const_param(self.index, self.name, ty) |
1134 | } | |
1135 | } | |
1136 | ||
e74abb32 | 1137 | rustc_index::newtype_index! { |
532ac7d7 XL |
1138 | /// A [De Bruijn index][dbi] is a standard means of representing |
1139 | /// regions (and perhaps later types) in a higher-ranked setting. In | |
1140 | /// particular, imagine a type like this: | |
1141 | /// | |
1142 | /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char) | |
1143 | /// ^ ^ | | | | |
1144 | /// | | | | | | |
1145 | /// | +------------+ 0 | | | |
1146 | /// | | | | |
1147 | /// +--------------------------------+ 1 | | |
1148 | /// | | | |
1149 | /// +------------------------------------------+ 0 | |
1150 | /// | |
1151 | /// In this type, there are two binders (the outer fn and the inner | |
1152 | /// fn). We need to be able to determine, for any given region, which | |
1153 | /// fn type it is bound by, the inner or the outer one. There are | |
1154 | /// various ways you can do this, but a De Bruijn index is one of the | |
1155 | /// more convenient and has some nice properties. The basic idea is to | |
1156 | /// count the number of binders, inside out. Some examples should help | |
1157 | /// clarify what I mean. | |
1158 | /// | |
1159 | /// Let's start with the reference type `&'b isize` that is the first | |
1160 | /// argument to the inner function. This region `'b` is assigned a De | |
1161 | /// Bruijn index of 0, meaning "the innermost binder" (in this case, a | |
1162 | /// fn). The region `'a` that appears in the second argument type (`&'a | |
1163 | /// isize`) would then be assigned a De Bruijn index of 1, meaning "the | |
1164 | /// second-innermost binder". (These indices are written on the arrays | |
1165 | /// in the diagram). | |
1166 | /// | |
1167 | /// What is interesting is that De Bruijn index attached to a particular | |
1168 | /// variable will vary depending on where it appears. For example, | |
1169 | /// the final type `&'a char` also refers to the region `'a` declared on | |
1170 | /// the outermost fn. But this time, this reference is not nested within | |
1171 | /// any other binders (i.e., it is not an argument to the inner fn, but | |
1172 | /// rather the outer one). Therefore, in this case, it is assigned a | |
1173 | /// De Bruijn index of 0, because the innermost binder in that location | |
1174 | /// is the outer fn. | |
1175 | /// | |
1176 | /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index | |
60c5eb7d | 1177 | #[derive(HashStable)] |
b7449926 | 1178 | pub struct DebruijnIndex { |
94b46f34 XL |
1179 | DEBUG_FORMAT = "DebruijnIndex({})", |
1180 | const INNERMOST = 0, | |
b7449926 XL |
1181 | } |
1182 | } | |
e9174d1e | 1183 | |
7cac9316 XL |
1184 | pub type Region<'tcx> = &'tcx RegionKind; |
1185 | ||
74b04a01 XL |
1186 | /// Representation of (lexical) regions. Note that the NLL checker |
1187 | /// uses a distinct representation of regions. For this reason, it | |
1188 | /// internally replaces all the regions with inference variables -- | |
1189 | /// the index of the variable is then used to index into internal NLL | |
1190 | /// data structures. See `rustc_mir::borrow_check` module for more | |
1191 | /// information. | |
1192 | /// | |
1193 | /// ## The Region lattice within a given function | |
1194 | /// | |
1195 | /// In general, the (lexical, and hence deprecated) region lattice | |
1196 | /// looks like | |
1197 | /// | |
1198 | /// ``` | |
1199 | /// static ----------+-----...------+ (greatest) | |
1200 | /// | | | | |
1201 | /// early-bound and | | | |
1202 | /// free regions | | | |
1203 | /// | | | | |
1204 | /// scope regions | | | |
1205 | /// | | | | |
1206 | /// empty(root) placeholder(U1) | | |
1207 | /// | / | | |
1208 | /// | / placeholder(Un) | |
1209 | /// empty(U1) -- / | |
1210 | /// | / | |
1211 | /// ... / | |
1212 | /// | / | |
1213 | /// empty(Un) -------- (smallest) | |
1214 | /// ``` | |
e9174d1e | 1215 | /// |
74b04a01 XL |
1216 | /// Early-bound/free regions are the named lifetimes in scope from the |
1217 | /// function declaration. They have relationships to one another | |
1218 | /// determined based on the declared relationships from the | |
1219 | /// function. They all collectively outlive the scope regions. (See | |
1220 | /// `RegionRelations` type, and particularly | |
1221 | /// `crate::infer::outlives::free_region_map::FreeRegionMap`.) | |
1222 | /// | |
1223 | /// The scope regions are related to one another based on the AST | |
1224 | /// structure. (See `RegionRelations` type, and particularly the | |
ba9703b0 | 1225 | /// `rustc_middle::middle::region::ScopeTree`.) |
74b04a01 XL |
1226 | /// |
1227 | /// Note that inference variables and bound regions are not included | |
1228 | /// in this diagram. In the case of inference variables, they should | |
1229 | /// be inferred to some other region from the diagram. In the case of | |
1230 | /// bound regions, they are excluded because they don't make sense to | |
1231 | /// include -- the diagram indicates the relationship between free | |
1232 | /// regions. | |
1233 | /// | |
1234 | /// ## Inference variables | |
1235 | /// | |
1236 | /// During region inference, we sometimes create inference variables, | |
1237 | /// represented as `ReVar`. These will be inferred by the code in | |
1238 | /// `infer::lexical_region_resolve` to some free region from the | |
1239 | /// lattice above (the minimal region that meets the | |
1240 | /// constraints). | |
1241 | /// | |
1242 | /// During NLL checking, where regions are defined differently, we | |
1243 | /// also use `ReVar` -- in that case, the index is used to index into | |
1244 | /// the NLL region checker's data structures. The variable may in fact | |
1245 | /// represent either a free region or an inference variable, in that | |
1246 | /// case. | |
e9174d1e SL |
1247 | /// |
1248 | /// ## Bound Regions | |
1249 | /// | |
1250 | /// These are regions that are stored behind a binder and must be substituted | |
9fa01778 XL |
1251 | /// with some concrete region before being used. There are two kind of |
1252 | /// bound regions: early-bound, which are bound in an item's `Generics`, | |
532ac7d7 | 1253 | /// and are substituted by a `InternalSubsts`, and late-bound, which are part of |
9fa01778 | 1254 | /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by |
e9174d1e SL |
1255 | /// the likes of `liberate_late_bound_regions`. The distinction exists |
1256 | /// because higher-ranked lifetimes aren't supported in all places. See [1][2]. | |
1257 | /// | |
9fa01778 | 1258 | /// Unlike `Param`s, bound regions are not supposed to exist "in the wild" |
0731742a | 1259 | /// outside their binder, e.g., in types passed to type inference, and |
0bf4aa26 | 1260 | /// should first be substituted (by placeholder regions, free regions, |
e9174d1e SL |
1261 | /// or region variables). |
1262 | /// | |
0bf4aa26 | 1263 | /// ## Placeholder and Free Regions |
e9174d1e SL |
1264 | /// |
1265 | /// One often wants to work with bound regions without knowing their precise | |
1266 | /// identity. For example, when checking a function, the lifetime of a borrow | |
1267 | /// can end up being assigned to some region parameter. In these cases, | |
1268 | /// it must be ensured that bounds on the region can't be accidentally | |
1269 | /// assumed without being checked. | |
1270 | /// | |
0bf4aa26 XL |
1271 | /// To do this, we replace the bound regions with placeholder markers, |
1272 | /// which don't satisfy any relation not explicitly provided. | |
e9174d1e | 1273 | /// |
9fa01778 | 1274 | /// There are two kinds of placeholder regions in rustc: `ReFree` and |
0bf4aa26 | 1275 | /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed |
e9174d1e SL |
1276 | /// to be used. These also support explicit bounds: both the internally-stored |
1277 | /// *scope*, which the region is assumed to outlive, as well as other | |
1278 | /// relations stored in the `FreeRegionMap`. Note that these relations | |
a7813a04 | 1279 | /// aren't checked when you `make_subregion` (or `eq_types`), only by |
e9174d1e SL |
1280 | /// `resolve_regions_and_report_errors`. |
1281 | /// | |
1282 | /// When working with higher-ranked types, some region relations aren't | |
1283 | /// yet known, so you can't just call `resolve_regions_and_report_errors`. | |
0bf4aa26 | 1284 | /// `RePlaceholder` is designed for this purpose. In these contexts, |
e9174d1e | 1285 | /// there's also the risk that some inference variable laying around will |
0bf4aa26 | 1286 | /// get unified with your placeholder region: if you want to check whether |
e9174d1e | 1287 | /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a` |
0bf4aa26 XL |
1288 | /// with a placeholder region `'%a`, the variable `'_` would just be |
1289 | /// instantiated to the placeholder region `'%a`, which is wrong because | |
e9174d1e | 1290 | /// the inference variable is supposed to satisfy the relation |
0bf4aa26 | 1291 | /// *for every value of the placeholder region*. To ensure that doesn't |
e9174d1e | 1292 | /// happen, you can use `leak_check`. This is more clearly explained |
ba9703b0 | 1293 | /// by the [rustc dev guide]. |
e9174d1e | 1294 | /// |
ff7c6d11 XL |
1295 | /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/ |
1296 | /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/ | |
ba9703b0 | 1297 | /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html |
abe05a73 | 1298 | #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)] |
7cac9316 | 1299 | pub enum RegionKind { |
9fa01778 XL |
1300 | /// Region bound in a type or fn declaration which will be |
1301 | /// substituted 'early' -- that is, at the same time when type | |
1302 | /// parameters are substituted. | |
e9174d1e SL |
1303 | ReEarlyBound(EarlyBoundRegion), |
1304 | ||
9fa01778 XL |
1305 | /// Region bound in a function scope, which will be substituted when the |
1306 | /// function is called. | |
e9174d1e SL |
1307 | ReLateBound(DebruijnIndex, BoundRegion), |
1308 | ||
1309 | /// When checking a function body, the types of all arguments and so forth | |
1310 | /// that refer to bound region parameters are modified to refer to free | |
1311 | /// region parameters. | |
1312 | ReFree(FreeRegion), | |
1313 | ||
ea8adc8c | 1314 | /// A concrete region naming some statically determined scope |
0731742a | 1315 | /// (e.g., an expression or sequence of statements) within the |
e9174d1e | 1316 | /// current function. |
ea8adc8c | 1317 | ReScope(region::Scope), |
e9174d1e SL |
1318 | |
1319 | /// Static data that has an "infinite" lifetime. Top in the region lattice. | |
1320 | ReStatic, | |
1321 | ||
9fa01778 | 1322 | /// A region variable. Should not exist after typeck. |
e9174d1e SL |
1323 | ReVar(RegionVid), |
1324 | ||
60c5eb7d | 1325 | /// A placeholder region -- basically, the higher-ranked version of `ReFree`. |
e9174d1e | 1326 | /// Should not exist after typeck. |
a1dfa0c6 | 1327 | RePlaceholder(ty::PlaceholderRegion), |
e9174d1e | 1328 | |
74b04a01 XL |
1329 | /// Empty lifetime is for data that is never accessed. We tag the |
1330 | /// empty lifetime with a universe -- the idea is that we don't | |
1331 | /// want `exists<'a> { forall<'b> { 'b: 'a } }` to be satisfiable. | |
1332 | /// Therefore, the `'empty` in a universe `U` is less than all | |
1333 | /// regions visible from `U`, but not less than regions not visible | |
1334 | /// from `U`. | |
1335 | ReEmpty(ty::UniverseIndex), | |
3157f602 | 1336 | |
94b46f34 | 1337 | /// Erased region, used by trait selection, in MIR and during codegen. |
3157f602 | 1338 | ReErased, |
e9174d1e SL |
1339 | } |
1340 | ||
416331ca | 1341 | impl<'tcx> rustc_serialize::UseSpecializedDecodable for Region<'tcx> {} |
9e0c209e | 1342 | |
abe05a73 | 1343 | #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)] |
e9174d1e | 1344 | pub struct EarlyBoundRegion { |
7cac9316 | 1345 | pub def_id: DefId, |
e9174d1e | 1346 | pub index: u32, |
e74abb32 | 1347 | pub name: Symbol, |
e9174d1e SL |
1348 | } |
1349 | ||
94b46f34 | 1350 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
e9174d1e | 1351 | pub struct TyVid { |
3157f602 | 1352 | pub index: u32, |
e9174d1e SL |
1353 | } |
1354 | ||
532ac7d7 XL |
1355 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
1356 | pub struct ConstVid<'tcx> { | |
1357 | pub index: u32, | |
1358 | pub phantom: PhantomData<&'tcx ()>, | |
1359 | } | |
1360 | ||
94b46f34 | 1361 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
e9174d1e | 1362 | pub struct IntVid { |
cc61c64b | 1363 | pub index: u32, |
e9174d1e SL |
1364 | } |
1365 | ||
94b46f34 | 1366 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
e9174d1e | 1367 | pub struct FloatVid { |
cc61c64b | 1368 | pub index: u32, |
e9174d1e SL |
1369 | } |
1370 | ||
e74abb32 | 1371 | rustc_index::newtype_index! { |
b7449926 | 1372 | pub struct RegionVid { |
ff7c6d11 | 1373 | DEBUG_FORMAT = custom, |
b7449926 XL |
1374 | } |
1375 | } | |
abe05a73 | 1376 | |
94b46f34 XL |
1377 | impl Atom for RegionVid { |
1378 | fn index(self) -> usize { | |
1379 | Idx::index(self) | |
1380 | } | |
1381 | } | |
1382 | ||
ba9703b0 XL |
1383 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)] |
1384 | #[derive(HashStable)] | |
e9174d1e SL |
1385 | pub enum InferTy { |
1386 | TyVar(TyVid), | |
1387 | IntVar(IntVid), | |
1388 | FloatVar(FloatVid), | |
1389 | ||
1390 | /// A `FreshTy` is one that is generated as a replacement for an | |
1391 | /// unbound type variable. This is convenient for caching etc. See | |
54a0048b | 1392 | /// `infer::freshen` for more details. |
e9174d1e SL |
1393 | FreshTy(u32), |
1394 | FreshIntTy(u32), | |
cc61c64b | 1395 | FreshFloatTy(u32), |
e9174d1e SL |
1396 | } |
1397 | ||
e74abb32 | 1398 | rustc_index::newtype_index! { |
a1dfa0c6 | 1399 | pub struct BoundVar { .. } |
0bf4aa26 XL |
1400 | } |
1401 | ||
ba9703b0 XL |
1402 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
1403 | #[derive(HashStable)] | |
0bf4aa26 | 1404 | pub struct BoundTy { |
a1dfa0c6 XL |
1405 | pub var: BoundVar, |
1406 | pub kind: BoundTyKind, | |
1407 | } | |
1408 | ||
ba9703b0 XL |
1409 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
1410 | #[derive(HashStable)] | |
a1dfa0c6 XL |
1411 | pub enum BoundTyKind { |
1412 | Anon, | |
e74abb32 | 1413 | Param(Symbol), |
b7449926 | 1414 | } |
0531ce1d | 1415 | |
a1dfa0c6 XL |
1416 | impl From<BoundVar> for BoundTy { |
1417 | fn from(var: BoundVar) -> Self { | |
dfeec247 | 1418 | BoundTy { var, kind: BoundTyKind::Anon } |
a1dfa0c6 XL |
1419 | } |
1420 | } | |
0bf4aa26 | 1421 | |
9e0c209e | 1422 | /// A `ProjectionPredicate` for an `ExistentialTraitRef`. |
60c5eb7d XL |
1423 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)] |
1424 | #[derive(HashStable, TypeFoldable)] | |
9e0c209e | 1425 | pub struct ExistentialProjection<'tcx> { |
041b39d2 | 1426 | pub item_def_id: DefId, |
532ac7d7 | 1427 | pub substs: SubstsRef<'tcx>, |
cc61c64b | 1428 | pub ty: Ty<'tcx>, |
e9174d1e SL |
1429 | } |
1430 | ||
9e0c209e SL |
1431 | pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>; |
1432 | ||
dc9dc135 | 1433 | impl<'tcx> ExistentialProjection<'tcx> { |
041b39d2 XL |
1434 | /// Extracts the underlying existential trait reference from this projection. |
1435 | /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`, | |
1436 | /// then this function would return a `exists T. T: Iterator` existential trait | |
1437 | /// reference. | |
dc9dc135 | 1438 | pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::ExistentialTraitRef<'tcx> { |
041b39d2 | 1439 | let def_id = tcx.associated_item(self.item_def_id).container.id(); |
dfeec247 | 1440 | ty::ExistentialTraitRef { def_id, substs: self.substs } |
9e0c209e SL |
1441 | } |
1442 | ||
dc9dc135 XL |
1443 | pub fn with_self_ty( |
1444 | &self, | |
1445 | tcx: TyCtxt<'tcx>, | |
1446 | self_ty: Ty<'tcx>, | |
1447 | ) -> ty::ProjectionPredicate<'tcx> { | |
9e0c209e | 1448 | // otherwise the escaping regions would be captured by the binders |
a1dfa0c6 | 1449 | debug_assert!(!self_ty.has_escaping_bound_vars()); |
9e0c209e | 1450 | |
476ff2be | 1451 | ty::ProjectionPredicate { |
041b39d2 XL |
1452 | projection_ty: ty::ProjectionTy { |
1453 | item_def_id: self.item_def_id, | |
94b46f34 | 1454 | substs: tcx.mk_substs_trait(self_ty, self.substs), |
041b39d2 | 1455 | }, |
cc61c64b | 1456 | ty: self.ty, |
476ff2be | 1457 | } |
e9174d1e SL |
1458 | } |
1459 | } | |
1460 | ||
dc9dc135 XL |
1461 | impl<'tcx> PolyExistentialProjection<'tcx> { |
1462 | pub fn with_self_ty( | |
1463 | &self, | |
1464 | tcx: TyCtxt<'tcx>, | |
1465 | self_ty: Ty<'tcx>, | |
1466 | ) -> ty::PolyProjectionPredicate<'tcx> { | |
476ff2be | 1467 | self.map_bound(|p| p.with_self_ty(tcx, self_ty)) |
e9174d1e | 1468 | } |
83c7162d XL |
1469 | |
1470 | pub fn item_def_id(&self) -> DefId { | |
ba9703b0 | 1471 | self.skip_binder().item_def_id |
83c7162d | 1472 | } |
e9174d1e SL |
1473 | } |
1474 | ||
1475 | impl DebruijnIndex { | |
94b46f34 | 1476 | /// Returns the resulting index when this value is moved into |
9fa01778 | 1477 | /// `amount` number of new binders. So, e.g., if you had |
94b46f34 XL |
1478 | /// |
1479 | /// for<'a> fn(&'a x) | |
1480 | /// | |
9fa01778 | 1481 | /// and you wanted to change it to |
94b46f34 XL |
1482 | /// |
1483 | /// for<'a> fn(for<'b> fn(&'a x)) | |
1484 | /// | |
0731742a | 1485 | /// you would need to shift the index for `'a` into a new binder. |
94b46f34 | 1486 | #[must_use] |
b7449926 XL |
1487 | pub fn shifted_in(self, amount: u32) -> DebruijnIndex { |
1488 | DebruijnIndex::from_u32(self.as_u32() + amount) | |
94b46f34 XL |
1489 | } |
1490 | ||
1491 | /// Update this index in place by shifting it "in" through | |
1492 | /// `amount` number of binders. | |
1493 | pub fn shift_in(&mut self, amount: u32) { | |
1494 | *self = self.shifted_in(amount); | |
e9174d1e SL |
1495 | } |
1496 | ||
94b46f34 XL |
1497 | /// Returns the resulting index when this value is moved out from |
1498 | /// `amount` number of new binders. | |
1499 | #[must_use] | |
b7449926 XL |
1500 | pub fn shifted_out(self, amount: u32) -> DebruijnIndex { |
1501 | DebruijnIndex::from_u32(self.as_u32() - amount) | |
94b46f34 XL |
1502 | } |
1503 | ||
1504 | /// Update in place by shifting out from `amount` binders. | |
1505 | pub fn shift_out(&mut self, amount: u32) { | |
1506 | *self = self.shifted_out(amount); | |
1507 | } | |
1508 | ||
9fa01778 | 1509 | /// Adjusts any De Bruijn indices so as to make `to_binder` the |
94b46f34 XL |
1510 | /// innermost binder. That is, if we have something bound at `to_binder`, |
1511 | /// it will now be bound at INNERMOST. This is an appropriate thing to do | |
1512 | /// when moving a region out from inside binders: | |
1513 | /// | |
1514 | /// ``` | |
1515 | /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _) | |
1516 | /// // Binder: D3 D2 D1 ^^ | |
1517 | /// ``` | |
1518 | /// | |
9fa01778 | 1519 | /// Here, the region `'a` would have the De Bruijn index D3, |
94b46f34 XL |
1520 | /// because it is the bound 3 binders out. However, if we wanted |
1521 | /// to refer to that region `'a` in the second argument (the `_`), | |
1522 | /// those two binders would not be in scope. In that case, we | |
1523 | /// might invoke `shift_out_to_binder(D3)`. This would adjust the | |
9fa01778 | 1524 | /// De Bruijn index of `'a` to D1 (the innermost binder). |
94b46f34 XL |
1525 | /// |
1526 | /// If we invoke `shift_out_to_binder` and the region is in fact | |
1527 | /// bound by one of the binders we are shifting out of, that is an | |
1528 | /// error (and should fail an assertion failure). | |
1529 | pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self { | |
b7449926 | 1530 | self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32()) |
e9174d1e SL |
1531 | } |
1532 | } | |
1533 | ||
7cac9316 XL |
1534 | /// Region utilities |
1535 | impl RegionKind { | |
0bf4aa26 XL |
1536 | /// Is this region named by the user? |
1537 | pub fn has_name(&self) -> bool { | |
1538 | match *self { | |
1539 | RegionKind::ReEarlyBound(ebr) => ebr.has_name(), | |
1540 | RegionKind::ReLateBound(_, br) => br.is_named(), | |
1541 | RegionKind::ReFree(fr) => fr.bound_region.is_named(), | |
1542 | RegionKind::ReScope(..) => false, | |
1543 | RegionKind::ReStatic => true, | |
1544 | RegionKind::ReVar(..) => false, | |
1545 | RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(), | |
74b04a01 | 1546 | RegionKind::ReEmpty(_) => false, |
0bf4aa26 | 1547 | RegionKind::ReErased => false, |
0bf4aa26 XL |
1548 | } |
1549 | } | |
1550 | ||
7cac9316 | 1551 | pub fn is_late_bound(&self) -> bool { |
e9174d1e | 1552 | match *self { |
e9174d1e | 1553 | ty::ReLateBound(..) => true, |
cc61c64b | 1554 | _ => false, |
e9174d1e SL |
1555 | } |
1556 | } | |
1557 | ||
0731742a XL |
1558 | pub fn is_placeholder(&self) -> bool { |
1559 | match *self { | |
1560 | ty::RePlaceholder(..) => true, | |
1561 | _ => false, | |
1562 | } | |
1563 | } | |
1564 | ||
94b46f34 | 1565 | pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool { |
e9174d1e | 1566 | match *self { |
94b46f34 | 1567 | ty::ReLateBound(debruijn, _) => debruijn >= index, |
e9174d1e SL |
1568 | _ => false, |
1569 | } | |
1570 | } | |
1571 | ||
9fa01778 | 1572 | /// Adjusts any De Bruijn indices so as to make `to_binder` the |
94b46f34 XL |
1573 | /// innermost binder. That is, if we have something bound at `to_binder`, |
1574 | /// it will now be bound at INNERMOST. This is an appropriate thing to do | |
1575 | /// when moving a region out from inside binders: | |
1576 | /// | |
1577 | /// ``` | |
1578 | /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _) | |
1579 | /// // Binder: D3 D2 D1 ^^ | |
1580 | /// ``` | |
1581 | /// | |
9fa01778 | 1582 | /// Here, the region `'a` would have the De Bruijn index D3, |
94b46f34 XL |
1583 | /// because it is the bound 3 binders out. However, if we wanted |
1584 | /// to refer to that region `'a` in the second argument (the `_`), | |
1585 | /// those two binders would not be in scope. In that case, we | |
1586 | /// might invoke `shift_out_to_binder(D3)`. This would adjust the | |
9fa01778 | 1587 | /// De Bruijn index of `'a` to D1 (the innermost binder). |
94b46f34 XL |
1588 | /// |
1589 | /// If we invoke `shift_out_to_binder` and the region is in fact | |
1590 | /// bound by one of the binders we are shifting out of, that is an | |
1591 | /// error (and should fail an assertion failure). | |
1592 | pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind { | |
e9174d1e | 1593 | match *self { |
dfeec247 XL |
1594 | ty::ReLateBound(debruijn, r) => { |
1595 | ty::ReLateBound(debruijn.shifted_out_to_binder(to_binder), r) | |
1596 | } | |
1597 | r => r, | |
e9174d1e SL |
1598 | } |
1599 | } | |
c30ab7b3 SL |
1600 | |
1601 | pub fn type_flags(&self) -> TypeFlags { | |
1602 | let mut flags = TypeFlags::empty(); | |
1603 | ||
1604 | match *self { | |
1605 | ty::ReVar(..) => { | |
ff7c6d11 | 1606 | flags = flags | TypeFlags::HAS_FREE_REGIONS; |
74b04a01 | 1607 | flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; |
c30ab7b3 | 1608 | flags = flags | TypeFlags::HAS_RE_INFER; |
ba9703b0 | 1609 | flags = flags | TypeFlags::STILL_FURTHER_SPECIALIZABLE; |
c30ab7b3 | 1610 | } |
0bf4aa26 | 1611 | ty::RePlaceholder(..) => { |
ff7c6d11 | 1612 | flags = flags | TypeFlags::HAS_FREE_REGIONS; |
74b04a01 | 1613 | flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; |
a1dfa0c6 | 1614 | flags = flags | TypeFlags::HAS_RE_PLACEHOLDER; |
ba9703b0 | 1615 | flags = flags | TypeFlags::STILL_FURTHER_SPECIALIZABLE; |
c30ab7b3 | 1616 | } |
ff7c6d11 XL |
1617 | ty::ReEarlyBound(..) => { |
1618 | flags = flags | TypeFlags::HAS_FREE_REGIONS; | |
74b04a01 XL |
1619 | flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; |
1620 | flags = flags | TypeFlags::HAS_RE_PARAM; | |
ba9703b0 | 1621 | flags = flags | TypeFlags::STILL_FURTHER_SPECIALIZABLE; |
ff7c6d11 | 1622 | } |
74b04a01 XL |
1623 | ty::ReFree { .. } | ty::ReScope { .. } => { |
1624 | flags = flags | TypeFlags::HAS_FREE_REGIONS; | |
1625 | flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS; | |
1626 | } | |
1627 | ty::ReEmpty(_) | ty::ReStatic => { | |
ff7c6d11 XL |
1628 | flags = flags | TypeFlags::HAS_FREE_REGIONS; |
1629 | } | |
74b04a01 XL |
1630 | ty::ReLateBound(..) => { |
1631 | flags = flags | TypeFlags::HAS_RE_LATE_BOUND; | |
1632 | } | |
1633 | ty::ReErased => { | |
1634 | flags = flags | TypeFlags::HAS_RE_ERASED; | |
1635 | } | |
c30ab7b3 SL |
1636 | } |
1637 | ||
1638 | debug!("type_flags({:?}) = {:?}", self, flags); | |
1639 | ||
1640 | flags | |
1641 | } | |
abe05a73 | 1642 | |
9fa01778 | 1643 | /// Given an early-bound or free region, returns the `DefId` where it was bound. |
abe05a73 XL |
1644 | /// For example, consider the regions in this snippet of code: |
1645 | /// | |
1646 | /// ``` | |
1647 | /// impl<'a> Foo { | |
1648 | /// ^^ -- early bound, declared on an impl | |
1649 | /// | |
1650 | /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c | |
1651 | /// ^^ ^^ ^ anonymous, late-bound | |
1652 | /// | early-bound, appears in where-clauses | |
1653 | /// late-bound, appears only in fn args | |
1654 | /// {..} | |
1655 | /// } | |
1656 | /// ``` | |
1657 | /// | |
9fa01778 | 1658 | /// Here, `free_region_binding_scope('a)` would return the `DefId` |
abe05a73 | 1659 | /// of the impl, and for all the other highlighted regions, it |
9fa01778 XL |
1660 | /// would return the `DefId` of the function. In other cases (not shown), this |
1661 | /// function might return the `DefId` of a closure. | |
dc9dc135 | 1662 | pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_>) -> DefId { |
abe05a73 | 1663 | match self { |
dfeec247 | 1664 | ty::ReEarlyBound(br) => tcx.parent(br.def_id).unwrap(), |
abe05a73 XL |
1665 | ty::ReFree(fr) => fr.scope, |
1666 | _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self), | |
1667 | } | |
1668 | } | |
e9174d1e SL |
1669 | } |
1670 | ||
7cac9316 | 1671 | /// Type utilities |
dc9dc135 XL |
1672 | impl<'tcx> TyS<'tcx> { |
1673 | #[inline] | |
b7449926 | 1674 | pub fn is_unit(&self) -> bool { |
e74abb32 | 1675 | match self.kind { |
b7449926 | 1676 | Tuple(ref tys) => tys.is_empty(), |
cc61c64b | 1677 | _ => false, |
e9174d1e SL |
1678 | } |
1679 | } | |
1680 | ||
dc9dc135 | 1681 | #[inline] |
5bcae85e | 1682 | pub fn is_never(&self) -> bool { |
e74abb32 | 1683 | match self.kind { |
b7449926 | 1684 | Never => true, |
5bcae85e SL |
1685 | _ => false, |
1686 | } | |
1687 | } | |
1688 | ||
0731742a XL |
1689 | /// Checks whether a type is definitely uninhabited. This is |
1690 | /// conservative: for some types that are uninhabited we return `false`, | |
1691 | /// but we only return `true` for types that are definitely uninhabited. | |
1692 | /// `ty.conservative_is_privately_uninhabited` implies that any value of type `ty` | |
1693 | /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero | |
1694 | /// size, to account for partial initialisation. See #49298 for details.) | |
dc9dc135 | 1695 | pub fn conservative_is_privately_uninhabited(&self, tcx: TyCtxt<'tcx>) -> bool { |
0731742a XL |
1696 | // FIXME(varkor): we can make this less conversative by substituting concrete |
1697 | // type arguments. | |
e74abb32 | 1698 | match self.kind { |
0731742a XL |
1699 | ty::Never => true, |
1700 | ty::Adt(def, _) if def.is_union() => { | |
1701 | // For now, `union`s are never considered uninhabited. | |
1702 | false | |
1703 | } | |
1704 | ty::Adt(def, _) => { | |
1705 | // Any ADT is uninhabited if either: | |
1706 | // (a) It has no variants (i.e. an empty `enum`); | |
1707 | // (b) Each of its variants (a single one in the case of a `struct`) has at least | |
1708 | // one uninhabited field. | |
1709 | def.variants.iter().all(|var| { | |
1710 | var.fields.iter().any(|field| { | |
1711 | tcx.type_of(field.did).conservative_is_privately_uninhabited(tcx) | |
1712 | }) | |
1713 | }) | |
1714 | } | |
dfeec247 XL |
1715 | ty::Tuple(..) => { |
1716 | self.tuple_fields().any(|ty| ty.conservative_is_privately_uninhabited(tcx)) | |
1717 | } | |
0731742a | 1718 | ty::Array(ty, len) => { |
416331ca | 1719 | match len.try_eval_usize(tcx, ParamEnv::empty()) { |
0731742a XL |
1720 | // If the array is definitely non-empty, it's uninhabited if |
1721 | // the type of its elements is uninhabited. | |
1722 | Some(n) if n != 0 => ty.conservative_is_privately_uninhabited(tcx), | |
dfeec247 | 1723 | _ => false, |
0731742a XL |
1724 | } |
1725 | } | |
1726 | ty::Ref(..) => { | |
1727 | // References to uninitialised memory is valid for any type, including | |
1728 | // uninhabited types, in unsafe code, so we treat all references as | |
1729 | // inhabited. | |
1730 | false | |
1731 | } | |
1732 | _ => false, | |
1733 | } | |
1734 | } | |
1735 | ||
dc9dc135 | 1736 | #[inline] |
0531ce1d | 1737 | pub fn is_primitive(&self) -> bool { |
e74abb32 | 1738 | match self.kind { |
b7449926 | 1739 | Bool | Char | Int(_) | Uint(_) | Float(_) => true, |
8bb4bdeb XL |
1740 | _ => false, |
1741 | } | |
1742 | } | |
1743 | ||
a1dfa0c6 | 1744 | #[inline] |
0531ce1d | 1745 | pub fn is_ty_var(&self) -> bool { |
e74abb32 | 1746 | match self.kind { |
b7449926 | 1747 | Infer(TyVar(_)) => true, |
9cc50fc6 SL |
1748 | _ => false, |
1749 | } | |
1750 | } | |
1751 | ||
dc9dc135 | 1752 | #[inline] |
0531ce1d | 1753 | pub fn is_ty_infer(&self) -> bool { |
e74abb32 | 1754 | match self.kind { |
b7449926 | 1755 | Infer(_) => true, |
cc61c64b | 1756 | _ => false, |
e9174d1e SL |
1757 | } |
1758 | } | |
1759 | ||
dc9dc135 | 1760 | #[inline] |
b039eaaf | 1761 | pub fn is_phantom_data(&self) -> bool { |
dfeec247 | 1762 | if let Adt(def, _) = self.kind { def.is_phantom_data() } else { false } |
b039eaaf SL |
1763 | } |
1764 | ||
dc9dc135 | 1765 | #[inline] |
dfeec247 XL |
1766 | pub fn is_bool(&self) -> bool { |
1767 | self.kind == Bool | |
1768 | } | |
e74abb32 XL |
1769 | |
1770 | /// Returns `true` if this type is a `str`. | |
1771 | #[inline] | |
dfeec247 XL |
1772 | pub fn is_str(&self) -> bool { |
1773 | self.kind == Str | |
1774 | } | |
e9174d1e | 1775 | |
dc9dc135 | 1776 | #[inline] |
9e0c209e | 1777 | pub fn is_param(&self, index: u32) -> bool { |
e74abb32 | 1778 | match self.kind { |
48663c56 | 1779 | ty::Param(ref data) => data.index == index, |
e9174d1e SL |
1780 | _ => false, |
1781 | } | |
1782 | } | |
1783 | ||
dc9dc135 | 1784 | #[inline] |
54a0048b | 1785 | pub fn is_slice(&self) -> bool { |
e74abb32 XL |
1786 | match self.kind { |
1787 | RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.kind { | |
b7449926 | 1788 | Slice(_) | Str => true, |
e9174d1e SL |
1789 | _ => false, |
1790 | }, | |
dfeec247 | 1791 | _ => false, |
e9174d1e SL |
1792 | } |
1793 | } | |
1794 | ||
e9174d1e SL |
1795 | #[inline] |
1796 | pub fn is_simd(&self) -> bool { | |
e74abb32 | 1797 | match self.kind { |
b7449926 | 1798 | Adt(def, _) => def.repr.simd(), |
cc61c64b | 1799 | _ => false, |
e9174d1e SL |
1800 | } |
1801 | } | |
1802 | ||
dc9dc135 | 1803 | pub fn sequence_element_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { |
e74abb32 | 1804 | match self.kind { |
b7449926 XL |
1805 | Array(ty, _) | Slice(ty) => ty, |
1806 | Str => tcx.mk_mach_uint(ast::UintTy::U8), | |
60c5eb7d | 1807 | _ => bug!("`sequence_element_type` called on non-sequence value: {}", self), |
e9174d1e SL |
1808 | } |
1809 | } | |
1810 | ||
dc9dc135 | 1811 | pub fn simd_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { |
e74abb32 | 1812 | match self.kind { |
60c5eb7d XL |
1813 | Adt(def, substs) => def.non_enum_variant().fields[0].ty(tcx, substs), |
1814 | _ => bug!("`simd_type` called on invalid type"), | |
1815 | } | |
1816 | } | |
1817 | ||
1818 | pub fn simd_size(&self, _tcx: TyCtxt<'tcx>) -> u64 { | |
1819 | // Parameter currently unused, but probably needed in the future to | |
1820 | // allow `#[repr(simd)] struct Simd<T, const N: usize>([T; N]);`. | |
1821 | match self.kind { | |
1822 | Adt(def, _) => def.non_enum_variant().fields.len() as u64, | |
1823 | _ => bug!("`simd_size` called on invalid type"), | |
e9174d1e SL |
1824 | } |
1825 | } | |
1826 | ||
60c5eb7d | 1827 | pub fn simd_size_and_type(&self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) { |
e74abb32 | 1828 | match self.kind { |
60c5eb7d XL |
1829 | Adt(def, substs) => { |
1830 | let variant = def.non_enum_variant(); | |
1831 | (variant.fields.len() as u64, variant.fields[0].ty(tcx, substs)) | |
1832 | } | |
1833 | _ => bug!("`simd_size_and_type` called on invalid type"), | |
e9174d1e SL |
1834 | } |
1835 | } | |
1836 | ||
dc9dc135 | 1837 | #[inline] |
e9174d1e | 1838 | pub fn is_region_ptr(&self) -> bool { |
e74abb32 | 1839 | match self.kind { |
b7449926 | 1840 | Ref(..) => true, |
cc61c64b | 1841 | _ => false, |
e9174d1e SL |
1842 | } |
1843 | } | |
1844 | ||
dc9dc135 | 1845 | #[inline] |
416331ca | 1846 | pub fn is_mutable_ptr(&self) -> bool { |
e74abb32 | 1847 | match self.kind { |
dfeec247 XL |
1848 | RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. }) |
1849 | | Ref(_, _, hir::Mutability::Mut) => true, | |
1850 | _ => false, | |
32a655c1 SL |
1851 | } |
1852 | } | |
1853 | ||
dc9dc135 | 1854 | #[inline] |
e9174d1e | 1855 | pub fn is_unsafe_ptr(&self) -> bool { |
e74abb32 | 1856 | match self.kind { |
ba9703b0 XL |
1857 | RawPtr(_) => true, |
1858 | _ => false, | |
e9174d1e SL |
1859 | } |
1860 | } | |
1861 | ||
416331ca XL |
1862 | /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer). |
1863 | #[inline] | |
1864 | pub fn is_any_ptr(&self) -> bool { | |
1865 | self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr() | |
1866 | } | |
1867 | ||
dc9dc135 | 1868 | #[inline] |
32a655c1 | 1869 | pub fn is_box(&self) -> bool { |
e74abb32 | 1870 | match self.kind { |
b7449926 | 1871 | Adt(def, _) => def.is_box(), |
32a655c1 SL |
1872 | _ => false, |
1873 | } | |
1874 | } | |
1875 | ||
60c5eb7d | 1876 | /// Panics if called on any type other than `Box<T>`. |
32a655c1 | 1877 | pub fn boxed_ty(&self) -> Ty<'tcx> { |
e74abb32 | 1878 | match self.kind { |
b7449926 | 1879 | Adt(def, substs) if def.is_box() => substs.type_at(0), |
32a655c1 | 1880 | _ => bug!("`boxed_ty` is called on non-box type {:?}", self), |
e9174d1e SL |
1881 | } |
1882 | } | |
1883 | ||
7cac9316 | 1884 | /// A scalar type is one that denotes an atomic datum, with no sub-components. |
b7449926 | 1885 | /// (A RawPtr is scalar because it represents a non-managed pointer, so its |
7cac9316 | 1886 | /// contents are abstract to rustc.) |
dc9dc135 | 1887 | #[inline] |
e9174d1e | 1888 | pub fn is_scalar(&self) -> bool { |
e74abb32 | 1889 | match self.kind { |
ba9703b0 XL |
1890 | Bool |
1891 | | Char | |
1892 | | Int(_) | |
1893 | | Float(_) | |
1894 | | Uint(_) | |
1895 | | Infer(IntVar(_) | FloatVar(_)) | |
1896 | | FnDef(..) | |
1897 | | FnPtr(_) | |
1898 | | RawPtr(_) => true, | |
dfeec247 | 1899 | _ => false, |
e9174d1e SL |
1900 | } |
1901 | } | |
1902 | ||
9fa01778 | 1903 | /// Returns `true` if this type is a floating point type. |
dc9dc135 | 1904 | #[inline] |
e9174d1e | 1905 | pub fn is_floating_point(&self) -> bool { |
e74abb32 | 1906 | match self.kind { |
dfeec247 | 1907 | Float(_) | Infer(FloatVar(_)) => true, |
e9174d1e SL |
1908 | _ => false, |
1909 | } | |
1910 | } | |
1911 | ||
dc9dc135 | 1912 | #[inline] |
e9174d1e | 1913 | pub fn is_trait(&self) -> bool { |
e74abb32 | 1914 | match self.kind { |
b7449926 | 1915 | Dynamic(..) => true, |
cc61c64b | 1916 | _ => false, |
e9174d1e SL |
1917 | } |
1918 | } | |
1919 | ||
dc9dc135 | 1920 | #[inline] |
ff7c6d11 | 1921 | pub fn is_enum(&self) -> bool { |
e74abb32 | 1922 | match self.kind { |
dfeec247 | 1923 | Adt(adt_def, _) => adt_def.is_enum(), |
ff7c6d11 XL |
1924 | _ => false, |
1925 | } | |
1926 | } | |
1927 | ||
dc9dc135 | 1928 | #[inline] |
7cac9316 | 1929 | pub fn is_closure(&self) -> bool { |
e74abb32 | 1930 | match self.kind { |
b7449926 | 1931 | Closure(..) => true, |
7cac9316 XL |
1932 | _ => false, |
1933 | } | |
1934 | } | |
1935 | ||
dc9dc135 | 1936 | #[inline] |
ff7c6d11 | 1937 | pub fn is_generator(&self) -> bool { |
e74abb32 | 1938 | match self.kind { |
b7449926 | 1939 | Generator(..) => true, |
ff7c6d11 XL |
1940 | _ => false, |
1941 | } | |
1942 | } | |
1943 | ||
a1dfa0c6 | 1944 | #[inline] |
e9174d1e | 1945 | pub fn is_integral(&self) -> bool { |
e74abb32 | 1946 | match self.kind { |
b7449926 | 1947 | Infer(IntVar(_)) | Int(_) | Uint(_) => true, |
dfeec247 | 1948 | _ => false, |
e9174d1e SL |
1949 | } |
1950 | } | |
1951 | ||
dc9dc135 | 1952 | #[inline] |
ff7c6d11 | 1953 | pub fn is_fresh_ty(&self) -> bool { |
e74abb32 | 1954 | match self.kind { |
b7449926 | 1955 | Infer(FreshTy(_)) => true, |
ff7c6d11 XL |
1956 | _ => false, |
1957 | } | |
1958 | } | |
1959 | ||
dc9dc135 | 1960 | #[inline] |
e9174d1e | 1961 | pub fn is_fresh(&self) -> bool { |
e74abb32 | 1962 | match self.kind { |
b7449926 XL |
1963 | Infer(FreshTy(_)) => true, |
1964 | Infer(FreshIntTy(_)) => true, | |
1965 | Infer(FreshFloatTy(_)) => true, | |
cc61c64b | 1966 | _ => false, |
e9174d1e SL |
1967 | } |
1968 | } | |
1969 | ||
dc9dc135 | 1970 | #[inline] |
e9174d1e | 1971 | pub fn is_char(&self) -> bool { |
e74abb32 | 1972 | match self.kind { |
b7449926 | 1973 | Char => true, |
cc61c64b | 1974 | _ => false, |
e9174d1e SL |
1975 | } |
1976 | } | |
1977 | ||
a1dfa0c6 | 1978 | #[inline] |
e9174d1e | 1979 | pub fn is_numeric(&self) -> bool { |
dc9dc135 | 1980 | self.is_integral() || self.is_floating_point() |
e9174d1e SL |
1981 | } |
1982 | ||
dc9dc135 | 1983 | #[inline] |
e9174d1e | 1984 | pub fn is_signed(&self) -> bool { |
e74abb32 | 1985 | match self.kind { |
b7449926 | 1986 | Int(_) => true, |
cc61c64b | 1987 | _ => false, |
e9174d1e SL |
1988 | } |
1989 | } | |
1990 | ||
dc9dc135 | 1991 | #[inline] |
416331ca | 1992 | pub fn is_ptr_sized_integral(&self) -> bool { |
e74abb32 | 1993 | match self.kind { |
0731742a XL |
1994 | Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true, |
1995 | _ => false, | |
1996 | } | |
1997 | } | |
1998 | ||
dc9dc135 | 1999 | #[inline] |
e9174d1e | 2000 | pub fn is_machine(&self) -> bool { |
e74abb32 | 2001 | match self.kind { |
b7449926 | 2002 | Int(..) | Uint(..) | Float(..) => true, |
cc61c64b | 2003 | _ => false, |
e9174d1e SL |
2004 | } |
2005 | } | |
2006 | ||
dc9dc135 | 2007 | #[inline] |
54a0048b | 2008 | pub fn has_concrete_skeleton(&self) -> bool { |
e74abb32 | 2009 | match self.kind { |
b7449926 | 2010 | Param(_) | Infer(_) | Error => false, |
54a0048b SL |
2011 | _ => true, |
2012 | } | |
2013 | } | |
2014 | ||
0731742a | 2015 | /// Returns the type and mutability of `*ty`. |
7cac9316 XL |
2016 | /// |
2017 | /// The parameter `explicit` indicates if this is an *explicit* dereference. | |
0731742a | 2018 | /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly. |
2c00a5a8 | 2019 | pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> { |
e74abb32 | 2020 | match self.kind { |
b7449926 | 2021 | Adt(def, _) if def.is_box() => { |
dfeec247 XL |
2022 | Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not }) |
2023 | } | |
b7449926 XL |
2024 | Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }), |
2025 | RawPtr(mt) if explicit => Some(mt), | |
cc61c64b | 2026 | _ => None, |
e9174d1e SL |
2027 | } |
2028 | } | |
2029 | ||
83c7162d | 2030 | /// Returns the type of `ty[i]`. |
e9174d1e | 2031 | pub fn builtin_index(&self) -> Option<Ty<'tcx>> { |
e74abb32 | 2032 | match self.kind { |
b7449926 | 2033 | Array(ty, _) | Slice(ty) => Some(ty), |
cc61c64b | 2034 | _ => None, |
e9174d1e SL |
2035 | } |
2036 | } | |
2037 | ||
dc9dc135 | 2038 | pub fn fn_sig(&self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> { |
e74abb32 | 2039 | match self.kind { |
dfeec247 | 2040 | FnDef(def_id, substs) => tcx.fn_sig(def_id).subst(tcx, substs), |
b7449926 | 2041 | FnPtr(f) => f, |
dfeec247 XL |
2042 | Error => { |
2043 | // ignore errors (#54954) | |
48663c56 XL |
2044 | ty::Binder::dummy(FnSig::fake()) |
2045 | } | |
ba9703b0 XL |
2046 | Closure(..) => bug!( |
2047 | "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`", | |
2048 | ), | |
dfeec247 | 2049 | _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self), |
e9174d1e SL |
2050 | } |
2051 | } | |
2052 | ||
dc9dc135 | 2053 | #[inline] |
e9174d1e | 2054 | pub fn is_fn(&self) -> bool { |
e74abb32 | 2055 | match self.kind { |
b7449926 | 2056 | FnDef(..) | FnPtr(_) => true, |
cc61c64b | 2057 | _ => false, |
e9174d1e SL |
2058 | } |
2059 | } | |
2060 | ||
dc9dc135 XL |
2061 | #[inline] |
2062 | pub fn is_fn_ptr(&self) -> bool { | |
e74abb32 | 2063 | match self.kind { |
dc9dc135 XL |
2064 | FnPtr(_) => true, |
2065 | _ => false, | |
2066 | } | |
2067 | } | |
2068 | ||
2069 | #[inline] | |
8faf50e0 | 2070 | pub fn is_impl_trait(&self) -> bool { |
e74abb32 | 2071 | match self.kind { |
b7449926 | 2072 | Opaque(..) => true, |
8faf50e0 | 2073 | _ => false, |
e9174d1e SL |
2074 | } |
2075 | } | |
2076 | ||
a1dfa0c6 | 2077 | #[inline] |
476ff2be | 2078 | pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> { |
e74abb32 | 2079 | match self.kind { |
b7449926 | 2080 | Adt(adt, _) => Some(adt), |
cc61c64b | 2081 | _ => None, |
e9174d1e SL |
2082 | } |
2083 | } | |
2084 | ||
416331ca XL |
2085 | /// Iterates over tuple fields. |
2086 | /// Panics when called on anything but a tuple. | |
dfeec247 | 2087 | pub fn tuple_fields(&self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> { |
e74abb32 | 2088 | match self.kind { |
416331ca XL |
2089 | Tuple(substs) => substs.iter().map(|field| field.expect_ty()), |
2090 | _ => bug!("tuple_fields called on non-tuple"), | |
2091 | } | |
2092 | } | |
2093 | ||
48663c56 | 2094 | /// If the type contains variants, returns the valid range of variant indices. |
60c5eb7d XL |
2095 | // |
2096 | // FIXME: This requires the optimized MIR in the case of generators. | |
48663c56 | 2097 | #[inline] |
dc9dc135 | 2098 | pub fn variant_range(&self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> { |
e74abb32 | 2099 | match self.kind { |
48663c56 | 2100 | TyKind::Adt(adt, _) => Some(adt.variant_range()), |
dfeec247 XL |
2101 | TyKind::Generator(def_id, substs, _) => { |
2102 | Some(substs.as_generator().variant_range(def_id, tcx)) | |
2103 | } | |
48663c56 XL |
2104 | _ => None, |
2105 | } | |
2106 | } | |
2107 | ||
2108 | /// If the type contains variants, returns the variant for `variant_index`. | |
2109 | /// Panics if `variant_index` is out of range. | |
60c5eb7d XL |
2110 | // |
2111 | // FIXME: This requires the optimized MIR in the case of generators. | |
48663c56 XL |
2112 | #[inline] |
2113 | pub fn discriminant_for_variant( | |
2114 | &self, | |
dc9dc135 XL |
2115 | tcx: TyCtxt<'tcx>, |
2116 | variant_index: VariantIdx, | |
48663c56 | 2117 | ) -> Option<Discr<'tcx>> { |
e74abb32 | 2118 | match self.kind { |
48663c56 | 2119 | TyKind::Adt(adt, _) => Some(adt.discriminant_for_variant(tcx, variant_index)), |
dfeec247 XL |
2120 | TyKind::Generator(def_id, substs, _) => { |
2121 | Some(substs.as_generator().discriminant_for_variant(def_id, tcx, variant_index)) | |
2122 | } | |
48663c56 XL |
2123 | _ => None, |
2124 | } | |
2125 | } | |
2126 | ||
ff7c6d11 XL |
2127 | /// When we create a closure, we record its kind (i.e., what trait |
2128 | /// it implements) into its `ClosureSubsts` using a type | |
2129 | /// parameter. This is kind of a phantom type, except that the | |
2130 | /// most convenient thing for us to are the integral types. This | |
2131 | /// function converts such a special type into the closure | |
2132 | /// kind. To go the other way, use | |
2133 | /// `tcx.closure_kind_ty(closure_kind)`. | |
2134 | /// | |
2135 | /// Note that during type checking, we use an inference variable | |
2136 | /// to represent the closure kind, because it has not yet been | |
2137 | /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`) | |
2138 | /// is complete, that type variable will be unified. | |
2139 | pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> { | |
e74abb32 | 2140 | match self.kind { |
b7449926 | 2141 | Int(int_ty) => match int_ty { |
ff7c6d11 XL |
2142 | ast::IntTy::I8 => Some(ty::ClosureKind::Fn), |
2143 | ast::IntTy::I16 => Some(ty::ClosureKind::FnMut), | |
2144 | ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce), | |
2145 | _ => bug!("cannot convert type `{:?}` to a closure kind", self), | |
2146 | }, | |
2147 | ||
e74abb32 XL |
2148 | // "Bound" types appear in canonical queries when the |
2149 | // closure type is not yet known | |
2150 | Bound(..) | Infer(_) => None, | |
ff7c6d11 | 2151 | |
b7449926 | 2152 | Error => Some(ty::ClosureKind::Fn), |
ff7c6d11 XL |
2153 | |
2154 | _ => bug!("cannot convert type `{:?}` to a closure kind", self), | |
2155 | } | |
2156 | } | |
b7449926 XL |
2157 | |
2158 | /// Fast path helper for testing if a type is `Sized`. | |
2159 | /// | |
2160 | /// Returning true means the type is known to be sized. Returning | |
2161 | /// `false` means nothing -- could be sized, might not be. | |
dc9dc135 | 2162 | pub fn is_trivially_sized(&self, tcx: TyCtxt<'tcx>) -> bool { |
e74abb32 | 2163 | match self.kind { |
ba9703b0 | 2164 | ty::Infer(ty::IntVar(_) | ty::FloatVar(_)) |
dfeec247 XL |
2165 | | ty::Uint(_) |
2166 | | ty::Int(_) | |
2167 | | ty::Bool | |
2168 | | ty::Float(_) | |
2169 | | ty::FnDef(..) | |
2170 | | ty::FnPtr(_) | |
2171 | | ty::RawPtr(..) | |
2172 | | ty::Char | |
2173 | | ty::Ref(..) | |
2174 | | ty::Generator(..) | |
2175 | | ty::GeneratorWitness(..) | |
2176 | | ty::Array(..) | |
2177 | | ty::Closure(..) | |
2178 | | ty::Never | |
2179 | | ty::Error => true, | |
2180 | ||
2181 | ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false, | |
2182 | ||
2183 | ty::Tuple(tys) => tys.iter().all(|ty| ty.expect_ty().is_trivially_sized(tcx)), | |
2184 | ||
2185 | ty::Adt(def, _substs) => def.sized_constraint(tcx).is_empty(), | |
b7449926 XL |
2186 | |
2187 | ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false, | |
2188 | ||
0bf4aa26 XL |
2189 | ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"), |
2190 | ||
b7449926 XL |
2191 | ty::Infer(ty::TyVar(_)) => false, |
2192 | ||
dfeec247 XL |
2193 | ty::Bound(..) |
2194 | | ty::Placeholder(..) | |
ba9703b0 | 2195 | | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => { |
dfeec247 XL |
2196 | bug!("`is_trivially_sized` applied to unexpected type: {:?}", self) |
2197 | } | |
b7449926 XL |
2198 | } |
2199 | } | |
e9174d1e | 2200 | } |
ea8adc8c XL |
2201 | |
2202 | /// Typed constant value. | |
ba9703b0 XL |
2203 | #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)] |
2204 | #[derive(HashStable)] | |
ea8adc8c XL |
2205 | pub struct Const<'tcx> { |
2206 | pub ty: Ty<'tcx>, | |
2207 | ||
60c5eb7d | 2208 | pub val: ConstKind<'tcx>, |
ea8adc8c XL |
2209 | } |
2210 | ||
9fa01778 | 2211 | #[cfg(target_arch = "x86_64")] |
60c5eb7d | 2212 | static_assert_size!(Const<'_>, 48); |
9fa01778 | 2213 | |
94b46f34 | 2214 | impl<'tcx> Const<'tcx> { |
ba9703b0 XL |
2215 | /// Literals and const generic parameters are eagerly converted to a constant, everything else |
2216 | /// becomes `Unevaluated`. | |
2217 | pub fn from_anon_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx Self { | |
2218 | debug!("Const::from_anon_const(id={:?})", def_id); | |
2219 | ||
2220 | let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); | |
2221 | ||
2222 | let body_id = match tcx.hir().get(hir_id) { | |
2223 | hir::Node::AnonConst(ac) => ac.body, | |
2224 | _ => span_bug!( | |
2225 | tcx.def_span(def_id.to_def_id()), | |
2226 | "from_anon_const can only process anonymous constants" | |
2227 | ), | |
2228 | }; | |
2229 | ||
2230 | let expr = &tcx.hir().body(body_id).value; | |
2231 | ||
2232 | let ty = tcx.type_of(def_id.to_def_id()); | |
2233 | ||
2234 | let lit_input = match expr.kind { | |
2235 | hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }), | |
2236 | hir::ExprKind::Unary(hir::UnOp::UnNeg, ref expr) => match expr.kind { | |
2237 | hir::ExprKind::Lit(ref lit) => { | |
2238 | Some(LitToConstInput { lit: &lit.node, ty, neg: true }) | |
2239 | } | |
2240 | _ => None, | |
2241 | }, | |
2242 | _ => None, | |
2243 | }; | |
2244 | ||
2245 | if let Some(lit_input) = lit_input { | |
2246 | // If an error occurred, ignore that it's a literal and leave reporting the error up to | |
2247 | // mir. | |
2248 | if let Ok(c) = tcx.at(expr.span).lit_to_const(lit_input) { | |
2249 | return c; | |
2250 | } else { | |
2251 | tcx.sess.delay_span_bug(expr.span, "Const::from_anon_const: couldn't lit_to_const"); | |
2252 | } | |
2253 | } | |
2254 | ||
2255 | // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments | |
2256 | // currently have to be wrapped in curly brackets, so it's necessary to special-case. | |
2257 | let expr = match &expr.kind { | |
2258 | hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => { | |
2259 | block.expr.as_ref().unwrap() | |
2260 | } | |
2261 | _ => expr, | |
2262 | }; | |
2263 | ||
2264 | use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath}; | |
2265 | let val = match expr.kind { | |
2266 | ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => { | |
2267 | // Find the name and index of the const parameter by indexing the generics of | |
2268 | // the parent item and construct a `ParamConst`. | |
2269 | let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap(); | |
2270 | let item_id = tcx.hir().get_parent_node(hir_id); | |
2271 | let item_def_id = tcx.hir().local_def_id(item_id); | |
2272 | let generics = tcx.generics_of(item_def_id); | |
2273 | let index = generics.param_def_id_to_index[&tcx.hir().local_def_id(hir_id)]; | |
2274 | let name = tcx.hir().name(hir_id); | |
2275 | ty::ConstKind::Param(ty::ParamConst::new(index, name)) | |
2276 | } | |
2277 | _ => ty::ConstKind::Unevaluated( | |
2278 | def_id.to_def_id(), | |
2279 | InternalSubsts::identity_for_item(tcx, def_id.to_def_id()), | |
2280 | None, | |
2281 | ), | |
2282 | }; | |
2283 | ||
2284 | tcx.mk_const(ty::Const { val, ty }) | |
2285 | } | |
2286 | ||
74b04a01 | 2287 | #[inline] |
ba9703b0 | 2288 | /// Interns the given value as a constant. |
74b04a01 XL |
2289 | pub fn from_value(tcx: TyCtxt<'tcx>, val: ConstValue<'tcx>, ty: Ty<'tcx>) -> &'tcx Self { |
2290 | tcx.mk_const(Self { val: ConstKind::Value(val), ty }) | |
2291 | } | |
2292 | ||
94b46f34 | 2293 | #[inline] |
ba9703b0 | 2294 | /// Interns the given scalar as a constant. |
dc9dc135 | 2295 | pub fn from_scalar(tcx: TyCtxt<'tcx>, val: Scalar, ty: Ty<'tcx>) -> &'tcx Self { |
74b04a01 | 2296 | Self::from_value(tcx, ConstValue::Scalar(val), ty) |
94b46f34 XL |
2297 | } |
2298 | ||
2299 | #[inline] | |
ba9703b0 | 2300 | /// Creates a constant with the given integer value and interns it. |
dc9dc135 | 2301 | pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> &'tcx Self { |
dfeec247 XL |
2302 | let size = tcx |
2303 | .layout_of(ty) | |
2304 | .unwrap_or_else(|e| panic!("could not compute layout for {:?}: {:?}", ty, e)) | |
2305 | .size; | |
dc9dc135 | 2306 | Self::from_scalar(tcx, Scalar::from_uint(bits, size), ty.value) |
94b46f34 XL |
2307 | } |
2308 | ||
2309 | #[inline] | |
ba9703b0 | 2310 | /// Creates an interned zst constant. |
dc9dc135 XL |
2311 | pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Self { |
2312 | Self::from_scalar(tcx, Scalar::zst(), ty) | |
94b46f34 XL |
2313 | } |
2314 | ||
2315 | #[inline] | |
ba9703b0 | 2316 | /// Creates an interned bool constant. |
dc9dc135 | 2317 | pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> &'tcx Self { |
94b46f34 XL |
2318 | Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool)) |
2319 | } | |
2320 | ||
2321 | #[inline] | |
ba9703b0 | 2322 | /// Creates an interned usize constant. |
dc9dc135 | 2323 | pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> &'tcx Self { |
94b46f34 XL |
2324 | Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize)) |
2325 | } | |
2326 | ||
2327 | #[inline] | |
ba9703b0 XL |
2328 | /// Attempts to evaluate the given constant to bits. Can fail to evaluate in the presence of |
2329 | /// generics (or erroneous code) or if the value can't be represented as bits (e.g. because it | |
2330 | /// contains const generic parameters or pointers). | |
416331ca XL |
2331 | pub fn try_eval_bits( |
2332 | &self, | |
2333 | tcx: TyCtxt<'tcx>, | |
2334 | param_env: ParamEnv<'tcx>, | |
2335 | ty: Ty<'tcx>, | |
2336 | ) -> Option<u128> { | |
2337 | assert_eq!(self.ty, ty); | |
416331ca | 2338 | let size = tcx.layout_of(param_env.with_reveal_all().and(ty)).ok()?.size; |
e74abb32 | 2339 | // if `ty` does not depend on generic parameters, use an empty param_env |
e1599b0c XL |
2340 | self.eval(tcx, param_env).val.try_to_bits(size) |
2341 | } | |
2342 | ||
2343 | #[inline] | |
ba9703b0 XL |
2344 | /// Tries to evaluate the constant if it is `Unevaluated`. If that doesn't succeed, return the |
2345 | /// unevaluated constant. | |
dfeec247 | 2346 | pub fn eval(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> &Const<'tcx> { |
ba9703b0 XL |
2347 | if let ConstKind::Unevaluated(did, substs, promoted) = self.val { |
2348 | use crate::mir::interpret::ErrorHandled; | |
2349 | ||
60c5eb7d XL |
2350 | let param_env_and_substs = param_env.with_reveal_all().and(substs); |
2351 | ||
ba9703b0 XL |
2352 | // HACK(eddyb) this erases lifetimes even though `const_eval_resolve` |
2353 | // also does later, but we want to do it before checking for | |
2354 | // inference variables. | |
2355 | let param_env_and_substs = tcx.erase_regions(¶m_env_and_substs); | |
2356 | ||
2357 | // HACK(eddyb) when the query key would contain inference variables, | |
2358 | // attempt using identity substs and `ParamEnv` instead, that will succeed | |
2359 | // when the expression doesn't depend on any parameters. | |
2360 | // FIXME(eddyb, skinny121) pass `InferCtxt` into here when it's available, so that | |
2361 | // we can call `infcx.const_eval_resolve` which handles inference variables. | |
2362 | let param_env_and_substs = if param_env_and_substs.needs_infer() { | |
2363 | tcx.param_env(did).and(InternalSubsts::identity_for_item(tcx, did)) | |
2364 | } else { | |
2365 | param_env_and_substs | |
2366 | }; | |
60c5eb7d | 2367 | |
ba9703b0 XL |
2368 | // FIXME(eddyb) maybe the `const_eval_*` methods should take |
2369 | // `ty::ParamEnvAnd<SubstsRef>` instead of having them separate. | |
60c5eb7d | 2370 | let (param_env, substs) = param_env_and_substs.into_parts(); |
dfeec247 XL |
2371 | // try to resolve e.g. associated constants to their definition on an impl, and then |
2372 | // evaluate the const. | |
ba9703b0 XL |
2373 | match tcx.const_eval_resolve(param_env, did, substs, promoted, None) { |
2374 | // NOTE(eddyb) `val` contains no lifetimes/types/consts, | |
2375 | // and we use the original type, so nothing from `substs` | |
2376 | // (which may be identity substs, see above), | |
2377 | // can leak through `val` into the const we return. | |
2378 | Ok(val) => Const::from_value(tcx, val, self.ty), | |
2379 | Err(ErrorHandled::TooGeneric | ErrorHandled::Linted) => self, | |
2380 | Err(ErrorHandled::Reported(ErrorReported)) => { | |
2381 | tcx.mk_const(ty::Const { val: ty::ConstKind::Error, ty: self.ty }) | |
60c5eb7d | 2382 | } |
dfeec247 | 2383 | } |
ba9703b0 XL |
2384 | } else { |
2385 | self | |
94b46f34 | 2386 | } |
94b46f34 XL |
2387 | } |
2388 | ||
2389 | #[inline] | |
416331ca XL |
2390 | pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> { |
2391 | self.try_eval_bits(tcx, param_env, tcx.types.bool).and_then(|v| match v { | |
94b46f34 XL |
2392 | 0 => Some(false), |
2393 | 1 => Some(true), | |
2394 | _ => None, | |
2395 | }) | |
2396 | } | |
2397 | ||
2398 | #[inline] | |
416331ca XL |
2399 | pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u64> { |
2400 | self.try_eval_bits(tcx, param_env, tcx.types.usize).map(|v| v as u64) | |
94b46f34 XL |
2401 | } |
2402 | ||
2403 | #[inline] | |
ba9703b0 | 2404 | /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type. |
416331ca | 2405 | pub fn eval_bits(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 { |
dfeec247 XL |
2406 | self.try_eval_bits(tcx, param_env, ty) |
2407 | .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self)) | |
94b46f34 XL |
2408 | } |
2409 | ||
2410 | #[inline] | |
ba9703b0 | 2411 | /// Panics if the value cannot be evaluated or doesn't contain a valid `usize`. |
416331ca XL |
2412 | pub fn eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u64 { |
2413 | self.eval_bits(tcx, param_env, tcx.types.usize) as u64 | |
94b46f34 XL |
2414 | } |
2415 | } | |
2416 | ||
416331ca | 2417 | impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {} |
532ac7d7 | 2418 | |
60c5eb7d | 2419 | /// Represents a constant in Rust. |
ba9703b0 XL |
2420 | #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash)] |
2421 | #[derive(HashStable)] | |
60c5eb7d XL |
2422 | pub enum ConstKind<'tcx> { |
2423 | /// A const generic parameter. | |
2424 | Param(ParamConst), | |
2425 | ||
2426 | /// Infer the value of the const. | |
2427 | Infer(InferConst<'tcx>), | |
2428 | ||
2429 | /// Bound const variable, used only when preparing a trait query. | |
2430 | Bound(DebruijnIndex, BoundVar), | |
2431 | ||
2432 | /// A placeholder const - universally quantified higher-ranked const. | |
2433 | Placeholder(ty::PlaceholderConst), | |
2434 | ||
2435 | /// Used in the HIR by using `Unevaluated` everywhere and later normalizing to one of the other | |
2436 | /// variants when the code is monomorphic enough for that. | |
dfeec247 | 2437 | Unevaluated(DefId, SubstsRef<'tcx>, Option<Promoted>), |
60c5eb7d XL |
2438 | |
2439 | /// Used to hold computed value. | |
2440 | Value(ConstValue<'tcx>), | |
ba9703b0 XL |
2441 | |
2442 | /// A placeholder for a const which could not be computed; this is | |
2443 | /// propagated to avoid useless error messages. | |
2444 | Error, | |
60c5eb7d XL |
2445 | } |
2446 | ||
2447 | #[cfg(target_arch = "x86_64")] | |
2448 | static_assert_size!(ConstKind<'_>, 40); | |
2449 | ||
2450 | impl<'tcx> ConstKind<'tcx> { | |
2451 | #[inline] | |
2452 | pub fn try_to_scalar(&self) -> Option<Scalar> { | |
dfeec247 | 2453 | if let ConstKind::Value(val) = self { val.try_to_scalar() } else { None } |
60c5eb7d XL |
2454 | } |
2455 | ||
2456 | #[inline] | |
ba9703b0 | 2457 | pub fn try_to_bits(&self, size: Size) -> Option<u128> { |
74b04a01 | 2458 | if let ConstKind::Value(val) = self { val.try_to_bits(size) } else { None } |
60c5eb7d XL |
2459 | } |
2460 | } | |
2461 | ||
532ac7d7 | 2462 | /// An inference variable for a const, for use in const generics. |
ba9703b0 XL |
2463 | #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash)] |
2464 | #[derive(HashStable)] | |
532ac7d7 XL |
2465 | pub enum InferConst<'tcx> { |
2466 | /// Infer the value of the const. | |
2467 | Var(ConstVid<'tcx>), | |
2468 | /// A fresh const variable. See `infer::freshen` for more details. | |
2469 | Fresh(u32), | |
532ac7d7 | 2470 | } |