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9fa01778 XL |
1 | //! Miscellaneous type-system utilities that are too small to deserve their own modules. |
2 | ||
9fa01778 | 3 | use crate::ich::NodeIdHashingMode; |
f9f354fc | 4 | use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags; |
3dfed10e | 5 | use crate::ty::fold::TypeFolder; |
ba9703b0 | 6 | use crate::ty::layout::IntegerExt; |
9fa01778 | 7 | use crate::ty::query::TyCtxtAt; |
29967ef6 | 8 | use crate::ty::subst::{GenericArgKind, Subst, SubstsRef}; |
9fa01778 | 9 | use crate::ty::TyKind::*; |
29967ef6 | 10 | use crate::ty::{self, DefIdTree, List, Ty, TyCtxt, TypeFoldable}; |
dfeec247 | 11 | use rustc_apfloat::Float as _; |
3dfed10e | 12 | use rustc_ast as ast; |
74b04a01 | 13 | use rustc_attr::{self as attr, SignedInt, UnsignedInt}; |
0731742a | 14 | use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
dfeec247 | 15 | use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; |
ba9703b0 | 16 | use rustc_errors::ErrorReported; |
dfeec247 XL |
17 | use rustc_hir as hir; |
18 | use rustc_hir::def::DefKind; | |
19 | use rustc_hir::def_id::DefId; | |
532ac7d7 | 20 | use rustc_macros::HashStable; |
cdc7bbd5 | 21 | use rustc_span::DUMMY_SP; |
ba9703b0 | 22 | use rustc_target::abi::{Integer, Size, TargetDataLayout}; |
74b04a01 | 23 | use smallvec::SmallVec; |
cdc7bbd5 | 24 | use std::{fmt, iter}; |
e9174d1e | 25 | |
0531ce1d XL |
26 | #[derive(Copy, Clone, Debug)] |
27 | pub struct Discr<'tcx> { | |
9fa01778 | 28 | /// Bit representation of the discriminant (e.g., `-128i8` is `0xFF_u128`). |
0531ce1d | 29 | pub val: u128, |
dfeec247 | 30 | pub ty: Ty<'tcx>, |
0531ce1d | 31 | } |
8bb4bdeb | 32 | |
0531ce1d | 33 | impl<'tcx> fmt::Display for Discr<'tcx> { |
0bf4aa26 | 34 | fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { |
1b1a35ee | 35 | match *self.ty.kind() { |
b7449926 | 36 | ty::Int(ity) => { |
5869c6ff | 37 | let size = ty::tls::with(|tcx| Integer::from_int_ty(&tcx, ity).size()); |
532ac7d7 | 38 | let x = self.val; |
0531ce1d | 39 | // sign extend the raw representation to be an i128 |
29967ef6 | 40 | let x = size.sign_extend(x) as i128; |
0531ce1d | 41 | write!(fmt, "{}", x) |
dfeec247 | 42 | } |
0531ce1d XL |
43 | _ => write!(fmt, "{}", self.val), |
44 | } | |
45 | } | |
cc61c64b | 46 | } |
8bb4bdeb | 47 | |
dfeec247 | 48 | fn signed_min(size: Size) -> i128 { |
29967ef6 | 49 | size.sign_extend(1_u128 << (size.bits() - 1)) as i128 |
dfeec247 XL |
50 | } |
51 | ||
52 | fn signed_max(size: Size) -> i128 { | |
74b04a01 | 53 | i128::MAX >> (128 - size.bits()) |
dfeec247 XL |
54 | } |
55 | ||
56 | fn unsigned_max(size: Size) -> u128 { | |
74b04a01 | 57 | u128::MAX >> (128 - size.bits()) |
dfeec247 XL |
58 | } |
59 | ||
60 | fn int_size_and_signed<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> (Size, bool) { | |
1b1a35ee | 61 | let (int, signed) = match *ty.kind() { |
5869c6ff XL |
62 | Int(ity) => (Integer::from_int_ty(&tcx, ity), true), |
63 | Uint(uty) => (Integer::from_uint_ty(&tcx, uty), false), | |
dfeec247 XL |
64 | _ => bug!("non integer discriminant"), |
65 | }; | |
66 | (int.size(), signed) | |
67 | } | |
68 | ||
0531ce1d | 69 | impl<'tcx> Discr<'tcx> { |
9fa01778 | 70 | /// Adds `1` to the value and wraps around if the maximum for the type is reached. |
dc9dc135 | 71 | pub fn wrap_incr(self, tcx: TyCtxt<'tcx>) -> Self { |
0531ce1d XL |
72 | self.checked_add(tcx, 1).0 |
73 | } | |
dc9dc135 | 74 | pub fn checked_add(self, tcx: TyCtxt<'tcx>, n: u128) -> (Self, bool) { |
dfeec247 XL |
75 | let (size, signed) = int_size_and_signed(tcx, self.ty); |
76 | let (val, oflo) = if signed { | |
77 | let min = signed_min(size); | |
78 | let max = signed_max(size); | |
29967ef6 | 79 | let val = size.sign_extend(self.val) as i128; |
74b04a01 | 80 | assert!(n < (i128::MAX as u128)); |
0531ce1d XL |
81 | let n = n as i128; |
82 | let oflo = val > max - n; | |
dfeec247 | 83 | let val = if oflo { min + (n - (max - val) - 1) } else { val + n }; |
0531ce1d XL |
84 | // zero the upper bits |
85 | let val = val as u128; | |
29967ef6 | 86 | let val = size.truncate(val); |
dfeec247 | 87 | (val, oflo) |
0531ce1d | 88 | } else { |
dfeec247 | 89 | let max = unsigned_max(size); |
0531ce1d XL |
90 | let val = self.val; |
91 | let oflo = val > max - n; | |
dfeec247 XL |
92 | let val = if oflo { n - (max - val) - 1 } else { val + n }; |
93 | (val, oflo) | |
94 | }; | |
95 | (Self { val, ty: self.ty }, oflo) | |
8bb4bdeb | 96 | } |
e9174d1e SL |
97 | } |
98 | ||
0531ce1d | 99 | pub trait IntTypeExt { |
dc9dc135 XL |
100 | fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx>; |
101 | fn disr_incr<'tcx>(&self, tcx: TyCtxt<'tcx>, val: Option<Discr<'tcx>>) -> Option<Discr<'tcx>>; | |
102 | fn initial_discriminant<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Discr<'tcx>; | |
0531ce1d XL |
103 | } |
104 | ||
e9174d1e | 105 | impl IntTypeExt for attr::IntType { |
dc9dc135 | 106 | fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { |
e9174d1e | 107 | match *self { |
dfeec247 XL |
108 | SignedInt(ast::IntTy::I8) => tcx.types.i8, |
109 | SignedInt(ast::IntTy::I16) => tcx.types.i16, | |
110 | SignedInt(ast::IntTy::I32) => tcx.types.i32, | |
111 | SignedInt(ast::IntTy::I64) => tcx.types.i64, | |
112 | SignedInt(ast::IntTy::I128) => tcx.types.i128, | |
113 | SignedInt(ast::IntTy::Isize) => tcx.types.isize, | |
114 | UnsignedInt(ast::UintTy::U8) => tcx.types.u8, | |
115 | UnsignedInt(ast::UintTy::U16) => tcx.types.u16, | |
116 | UnsignedInt(ast::UintTy::U32) => tcx.types.u32, | |
117 | UnsignedInt(ast::UintTy::U64) => tcx.types.u64, | |
118 | UnsignedInt(ast::UintTy::U128) => tcx.types.u128, | |
2c00a5a8 | 119 | UnsignedInt(ast::UintTy::Usize) => tcx.types.usize, |
e9174d1e SL |
120 | } |
121 | } | |
122 | ||
dc9dc135 | 123 | fn initial_discriminant<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Discr<'tcx> { |
dfeec247 | 124 | Discr { val: 0, ty: self.to_ty(tcx) } |
e9174d1e SL |
125 | } |
126 | ||
dc9dc135 | 127 | fn disr_incr<'tcx>(&self, tcx: TyCtxt<'tcx>, val: Option<Discr<'tcx>>) -> Option<Discr<'tcx>> { |
a7813a04 | 128 | if let Some(val) = val { |
0531ce1d XL |
129 | assert_eq!(self.to_ty(tcx), val.ty); |
130 | let (new, oflo) = val.checked_add(tcx, 1); | |
dfeec247 | 131 | if oflo { None } else { Some(new) } |
a7813a04 XL |
132 | } else { |
133 | Some(self.initial_discriminant(tcx)) | |
134 | } | |
e9174d1e SL |
135 | } |
136 | } | |
137 | ||
dc9dc135 | 138 | impl<'tcx> TyCtxt<'tcx> { |
cc61c64b XL |
139 | /// Creates a hash of the type `Ty` which will be the same no matter what crate |
140 | /// context it's calculated within. This is used by the `type_id` intrinsic. | |
141 | pub fn type_id_hash(self, ty: Ty<'tcx>) -> u64 { | |
142 | let mut hasher = StableHasher::new(); | |
ea8adc8c | 143 | let mut hcx = self.create_stable_hashing_context(); |
cc61c64b | 144 | |
3b2f2976 XL |
145 | // We want the type_id be independent of the types free regions, so we |
146 | // erase them. The erase_regions() call will also anonymize bound | |
147 | // regions, which is desirable too. | |
fc512014 | 148 | let ty = self.erase_regions(ty); |
3b2f2976 | 149 | |
cc61c64b XL |
150 | hcx.while_hashing_spans(false, |hcx| { |
151 | hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { | |
152 | ty.hash_stable(hcx, &mut hasher); | |
153 | }); | |
154 | }); | |
155 | hasher.finish() | |
156 | } | |
cc61c64b | 157 | |
5bcae85e | 158 | pub fn has_error_field(self, ty: Ty<'tcx>) -> bool { |
1b1a35ee | 159 | if let ty::Adt(def, substs) = *ty.kind() { |
0bf4aa26 XL |
160 | for field in def.all_fields() { |
161 | let field_ty = field.ty(self, substs); | |
1b1a35ee | 162 | if let Error(_) = field_ty.kind() { |
0bf4aa26 | 163 | return true; |
5bcae85e SL |
164 | } |
165 | } | |
5bcae85e SL |
166 | } |
167 | false | |
168 | } | |
169 | ||
416331ca XL |
170 | /// Attempts to returns the deeply last field of nested structures, but |
171 | /// does not apply any normalization in its search. Returns the same type | |
172 | /// if input `ty` is not a structure at all. | |
dfeec247 | 173 | pub fn struct_tail_without_normalization(self, ty: Ty<'tcx>) -> Ty<'tcx> { |
416331ca XL |
174 | let tcx = self; |
175 | tcx.struct_tail_with_normalize(ty, |ty| ty) | |
176 | } | |
177 | ||
178 | /// Returns the deeply last field of nested structures, or the same type if | |
179 | /// not a structure at all. Corresponds to the only possible unsized field, | |
180 | /// and its type can be used to determine unsizing strategy. | |
181 | /// | |
182 | /// Should only be called if `ty` has no inference variables and does not | |
183 | /// need its lifetimes preserved (e.g. as part of codegen); otherwise | |
184 | /// normalization attempt may cause compiler bugs. | |
dfeec247 XL |
185 | pub fn struct_tail_erasing_lifetimes( |
186 | self, | |
187 | ty: Ty<'tcx>, | |
188 | param_env: ty::ParamEnv<'tcx>, | |
189 | ) -> Ty<'tcx> { | |
416331ca XL |
190 | let tcx = self; |
191 | tcx.struct_tail_with_normalize(ty, |ty| tcx.normalize_erasing_regions(param_env, ty)) | |
192 | } | |
193 | ||
194 | /// Returns the deeply last field of nested structures, or the same type if | |
195 | /// not a structure at all. Corresponds to the only possible unsized field, | |
196 | /// and its type can be used to determine unsizing strategy. | |
197 | /// | |
198 | /// This is parameterized over the normalization strategy (i.e. how to | |
199 | /// handle `<T as Trait>::Assoc` and `impl Trait`); pass the identity | |
200 | /// function to indicate no normalization should take place. | |
201 | /// | |
202 | /// See also `struct_tail_erasing_lifetimes`, which is suitable for use | |
203 | /// during codegen. | |
dfeec247 XL |
204 | pub fn struct_tail_with_normalize( |
205 | self, | |
206 | mut ty: Ty<'tcx>, | |
207 | normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>, | |
208 | ) -> Ty<'tcx> { | |
fc512014 XL |
209 | for iteration in 0.. { |
210 | if !self.sess.recursion_limit().value_within_limit(iteration) { | |
211 | return self.ty_error_with_message( | |
212 | DUMMY_SP, | |
213 | &format!("reached the recursion limit finding the struct tail for {}", ty), | |
214 | ); | |
215 | } | |
1b1a35ee | 216 | match *ty.kind() { |
b7449926 | 217 | ty::Adt(def, substs) => { |
7cac9316 XL |
218 | if !def.is_struct() { |
219 | break; | |
220 | } | |
2c00a5a8 | 221 | match def.non_enum_variant().fields.last() { |
7cac9316 XL |
222 | Some(f) => ty = f.ty(self, substs), |
223 | None => break, | |
224 | } | |
225 | } | |
226 | ||
b7449926 | 227 | ty::Tuple(tys) => { |
7cac9316 | 228 | if let Some((&last_ty, _)) = tys.split_last() { |
48663c56 | 229 | ty = last_ty.expect_ty(); |
7cac9316 XL |
230 | } else { |
231 | break; | |
232 | } | |
233 | } | |
234 | ||
416331ca XL |
235 | ty::Projection(_) | ty::Opaque(..) => { |
236 | let normalized = normalize(ty); | |
237 | if ty == normalized { | |
238 | return ty; | |
239 | } else { | |
240 | ty = normalized; | |
241 | } | |
242 | } | |
243 | ||
7cac9316 XL |
244 | _ => { |
245 | break; | |
246 | } | |
e9174d1e SL |
247 | } |
248 | } | |
249 | ty | |
250 | } | |
251 | ||
60c5eb7d | 252 | /// Same as applying `struct_tail` on `source` and `target`, but only |
e9174d1e SL |
253 | /// keeps going as long as the two types are instances of the same |
254 | /// structure definitions. | |
a1dfa0c6 | 255 | /// For `(Foo<Foo<T>>, Foo<dyn Trait>)`, the result will be `(Foo<T>, Trait)`, |
e9174d1e | 256 | /// whereas struct_tail produces `T`, and `Trait`, respectively. |
416331ca XL |
257 | /// |
258 | /// Should only be called if the types have no inference variables and do | |
60c5eb7d | 259 | /// not need their lifetimes preserved (e.g., as part of codegen); otherwise, |
416331ca | 260 | /// normalization attempt may cause compiler bugs. |
dfeec247 XL |
261 | pub fn struct_lockstep_tails_erasing_lifetimes( |
262 | self, | |
263 | source: Ty<'tcx>, | |
264 | target: Ty<'tcx>, | |
265 | param_env: ty::ParamEnv<'tcx>, | |
266 | ) -> (Ty<'tcx>, Ty<'tcx>) { | |
416331ca | 267 | let tcx = self; |
dfeec247 XL |
268 | tcx.struct_lockstep_tails_with_normalize(source, target, |ty| { |
269 | tcx.normalize_erasing_regions(param_env, ty) | |
270 | }) | |
416331ca XL |
271 | } |
272 | ||
60c5eb7d | 273 | /// Same as applying `struct_tail` on `source` and `target`, but only |
416331ca XL |
274 | /// keeps going as long as the two types are instances of the same |
275 | /// structure definitions. | |
276 | /// For `(Foo<Foo<T>>, Foo<dyn Trait>)`, the result will be `(Foo<T>, Trait)`, | |
277 | /// whereas struct_tail produces `T`, and `Trait`, respectively. | |
278 | /// | |
279 | /// See also `struct_lockstep_tails_erasing_lifetimes`, which is suitable for use | |
280 | /// during codegen. | |
dfeec247 XL |
281 | pub fn struct_lockstep_tails_with_normalize( |
282 | self, | |
283 | source: Ty<'tcx>, | |
284 | target: Ty<'tcx>, | |
285 | normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>, | |
286 | ) -> (Ty<'tcx>, Ty<'tcx>) { | |
e9174d1e | 287 | let (mut a, mut b) = (source, target); |
041b39d2 | 288 | loop { |
1b1a35ee | 289 | match (&a.kind(), &b.kind()) { |
b7449926 | 290 | (&Adt(a_def, a_substs), &Adt(b_def, b_substs)) |
dfeec247 XL |
291 | if a_def == b_def && a_def.is_struct() => |
292 | { | |
2c00a5a8 | 293 | if let Some(f) = a_def.non_enum_variant().fields.last() { |
041b39d2 XL |
294 | a = f.ty(self, a_substs); |
295 | b = f.ty(self, b_substs); | |
296 | } else { | |
297 | break; | |
298 | } | |
dfeec247 XL |
299 | } |
300 | (&Tuple(a_tys), &Tuple(b_tys)) if a_tys.len() == b_tys.len() => { | |
041b39d2 | 301 | if let Some(a_last) = a_tys.last() { |
48663c56 XL |
302 | a = a_last.expect_ty(); |
303 | b = b_tys.last().unwrap().expect_ty(); | |
041b39d2 XL |
304 | } else { |
305 | break; | |
306 | } | |
dfeec247 | 307 | } |
ba9703b0 XL |
308 | (ty::Projection(_) | ty::Opaque(..), _) |
309 | | (_, ty::Projection(_) | ty::Opaque(..)) => { | |
416331ca XL |
310 | // If either side is a projection, attempt to |
311 | // progress via normalization. (Should be safe to | |
312 | // apply to both sides as normalization is | |
313 | // idempotent.) | |
314 | let a_norm = normalize(a); | |
315 | let b_norm = normalize(b); | |
316 | if a == a_norm && b == b_norm { | |
317 | break; | |
318 | } else { | |
319 | a = a_norm; | |
320 | b = b_norm; | |
321 | } | |
322 | } | |
323 | ||
cc61c64b | 324 | _ => break, |
e9174d1e SL |
325 | } |
326 | } | |
327 | (a, b) | |
328 | } | |
329 | ||
8bb4bdeb XL |
330 | /// Calculate the destructor of a given type. |
331 | pub fn calculate_dtor( | |
332 | self, | |
333 | adt_did: DefId, | |
29967ef6 | 334 | validate: impl Fn(Self, DefId) -> Result<(), ErrorReported>, |
8bb4bdeb | 335 | ) -> Option<ty::Destructor> { |
ba9703b0 | 336 | let drop_trait = self.lang_items().drop_trait()?; |
9fa01778 | 337 | self.ensure().coherent_trait(drop_trait); |
8bb4bdeb | 338 | |
7cac9316 | 339 | let ty = self.type_of(adt_did); |
29967ef6 | 340 | let dtor_did = self.find_map_relevant_impl(drop_trait, ty, |impl_did| { |
74b04a01 | 341 | if let Some(item) = self.associated_items(impl_did).in_definition_order().next() { |
0bf4aa26 | 342 | if validate(self, impl_did).is_ok() { |
29967ef6 | 343 | return Some(item.def_id); |
8bb4bdeb XL |
344 | } |
345 | } | |
29967ef6 | 346 | None |
8bb4bdeb XL |
347 | }); |
348 | ||
ff7c6d11 | 349 | Some(ty::Destructor { did: dtor_did? }) |
cc61c64b XL |
350 | } |
351 | ||
9fa01778 | 352 | /// Returns the set of types that are required to be alive in |
cc61c64b XL |
353 | /// order to run the destructor of `def` (see RFCs 769 and |
354 | /// 1238). | |
355 | /// | |
356 | /// Note that this returns only the constraints for the | |
357 | /// destructor of `def` itself. For the destructors of the | |
358 | /// contents, you need `adt_dtorck_constraint`. | |
dfeec247 | 359 | pub fn destructor_constraints(self, def: &'tcx ty::AdtDef) -> Vec<ty::subst::GenericArg<'tcx>> { |
cc61c64b XL |
360 | let dtor = match def.destructor(self) { |
361 | None => { | |
362 | debug!("destructor_constraints({:?}) - no dtor", def.did); | |
dfeec247 | 363 | return vec![]; |
cc61c64b | 364 | } |
dfeec247 | 365 | Some(dtor) => dtor.did, |
e9174d1e | 366 | }; |
b039eaaf | 367 | |
cc61c64b | 368 | let impl_def_id = self.associated_item(dtor).container.id(); |
7cac9316 | 369 | let impl_generics = self.generics_of(impl_def_id); |
cc61c64b XL |
370 | |
371 | // We have a destructor - all the parameters that are not | |
372 | // pure_wrt_drop (i.e, don't have a #[may_dangle] attribute) | |
373 | // must be live. | |
374 | ||
375 | // We need to return the list of parameters from the ADTs | |
376 | // generics/substs that correspond to impure parameters on the | |
377 | // impl's generics. This is a bit ugly, but conceptually simple: | |
378 | // | |
379 | // Suppose our ADT looks like the following | |
380 | // | |
381 | // struct S<X, Y, Z>(X, Y, Z); | |
382 | // | |
383 | // and the impl is | |
384 | // | |
385 | // impl<#[may_dangle] P0, P1, P2> Drop for S<P1, P2, P0> | |
386 | // | |
387 | // We want to return the parameters (X, Y). For that, we match | |
388 | // up the item-substs <X, Y, Z> with the substs on the impl ADT, | |
389 | // <P1, P2, P0>, and then look up which of the impl substs refer to | |
390 | // parameters marked as pure. | |
391 | ||
1b1a35ee | 392 | let impl_substs = match *self.type_of(impl_def_id).kind() { |
b7449926 | 393 | ty::Adt(def_, substs) if def_ == def => substs, |
dfeec247 | 394 | _ => bug!(), |
cc61c64b XL |
395 | }; |
396 | ||
1b1a35ee | 397 | let item_substs = match *self.type_of(def.did).kind() { |
b7449926 | 398 | ty::Adt(def_, substs) if def_ == def => substs, |
dfeec247 | 399 | _ => bug!(), |
cc61c64b XL |
400 | }; |
401 | ||
cdc7bbd5 | 402 | let result = iter::zip(item_substs, impl_substs) |
f9f354fc | 403 | .filter(|&(_, k)| { |
0531ce1d | 404 | match k.unpack() { |
e74abb32 | 405 | GenericArgKind::Lifetime(&ty::RegionKind::ReEarlyBound(ref ebr)) => { |
0531ce1d XL |
406 | !impl_generics.region_param(ebr, self).pure_wrt_drop |
407 | } | |
dfeec247 | 408 | GenericArgKind::Type(&ty::TyS { kind: ty::Param(ref pt), .. }) => { |
0531ce1d XL |
409 | !impl_generics.type_param(pt, self).pure_wrt_drop |
410 | } | |
e74abb32 | 411 | GenericArgKind::Const(&ty::Const { |
dfeec247 XL |
412 | val: ty::ConstKind::Param(ref pc), .. |
413 | }) => !impl_generics.const_param(pc, self).pure_wrt_drop, | |
414 | GenericArgKind::Lifetime(_) | |
415 | | GenericArgKind::Type(_) | |
416 | | GenericArgKind::Const(_) => { | |
532ac7d7 | 417 | // Not a type, const or region param: this should be reported |
0531ce1d XL |
418 | // as an error. |
419 | false | |
420 | } | |
cc61c64b | 421 | } |
0bf4aa26 | 422 | }) |
f9f354fc | 423 | .map(|(item_param, _)| item_param) |
0bf4aa26 | 424 | .collect(); |
cc61c64b XL |
425 | debug!("destructor_constraint({:?}) = {:?}", def.did, result); |
426 | result | |
b039eaaf | 427 | } |
9e0c209e | 428 | |
9fa01778 XL |
429 | /// Returns `true` if `def_id` refers to a closure (e.g., `|x| x * 2`). Note |
430 | /// that closures have a `DefId`, but the closure *expression* also | |
8faf50e0 XL |
431 | /// has a `HirId` that is located within the context where the |
432 | /// closure appears (and, sadly, a corresponding `NodeId`, since | |
433 | /// those are not yet phased out). The parent of the closure's | |
9fa01778 | 434 | /// `DefId` will also be the context where it appears. |
abe05a73 | 435 | pub fn is_closure(self, def_id: DefId) -> bool { |
f9f354fc | 436 | matches!(self.def_kind(def_id), DefKind::Closure | DefKind::Generator) |
abe05a73 XL |
437 | } |
438 | ||
9fa01778 | 439 | /// Returns `true` if `def_id` refers to a trait (i.e., `trait Foo { ... }`). |
8faf50e0 | 440 | pub fn is_trait(self, def_id: DefId) -> bool { |
f9f354fc | 441 | self.def_kind(def_id) == DefKind::Trait |
8faf50e0 XL |
442 | } |
443 | ||
9fa01778 XL |
444 | /// Returns `true` if `def_id` refers to a trait alias (i.e., `trait Foo = ...;`), |
445 | /// and `false` otherwise. | |
446 | pub fn is_trait_alias(self, def_id: DefId) -> bool { | |
f9f354fc | 447 | self.def_kind(def_id) == DefKind::TraitAlias |
9fa01778 XL |
448 | } |
449 | ||
450 | /// Returns `true` if this `DefId` refers to the implicit constructor for | |
451 | /// a tuple struct like `struct Foo(u32)`, and `false` otherwise. | |
532ac7d7 | 452 | pub fn is_constructor(self, def_id: DefId) -> bool { |
f9f354fc | 453 | matches!(self.def_kind(def_id), DefKind::Ctor(..)) |
8faf50e0 XL |
454 | } |
455 | ||
dc9dc135 | 456 | /// Given the def-ID of a fn or closure, returns the def-ID of |
ff7c6d11 | 457 | /// the innermost fn item that the closure is contained within. |
9fa01778 | 458 | /// This is a significant `DefId` because, when we do |
ff7c6d11 | 459 | /// type-checking, we type-check this fn item and all of its |
9fa01778 | 460 | /// (transitive) closures together. Therefore, when we fetch the |
3dfed10e XL |
461 | /// `typeck` the closure, for example, we really wind up |
462 | /// fetching the `typeck` the enclosing fn item. | |
cc61c64b | 463 | pub fn closure_base_def_id(self, def_id: DefId) -> DefId { |
476ff2be | 464 | let mut def_id = def_id; |
abe05a73 | 465 | while self.is_closure(def_id) { |
532ac7d7 | 466 | def_id = self.parent(def_id).unwrap_or_else(|| { |
476ff2be SL |
467 | bug!("closure {:?} has no parent", def_id); |
468 | }); | |
469 | } | |
470 | def_id | |
9e0c209e | 471 | } |
cc61c64b | 472 | |
9fa01778 | 473 | /// Given the `DefId` and substs a closure, creates the type of |
ff7c6d11 XL |
474 | /// `self` argument that the closure expects. For example, for a |
475 | /// `Fn` closure, this would return a reference type `&T` where | |
9fa01778 | 476 | /// `T = closure_ty`. |
ff7c6d11 XL |
477 | /// |
478 | /// Returns `None` if this closure's kind has not yet been inferred. | |
479 | /// This should only be possible during type checking. | |
480 | /// | |
481 | /// Note that the return value is a late-bound region and hence | |
482 | /// wrapped in a binder. | |
dfeec247 XL |
483 | pub fn closure_env_ty( |
484 | self, | |
485 | closure_def_id: DefId, | |
486 | closure_substs: SubstsRef<'tcx>, | |
cdc7bbd5 XL |
487 | env_region: ty::RegionKind, |
488 | ) -> Option<Ty<'tcx>> { | |
ff7c6d11 | 489 | let closure_ty = self.mk_closure(closure_def_id, closure_substs); |
ba9703b0 | 490 | let closure_kind_ty = closure_substs.as_closure().kind_ty(); |
ff7c6d11 XL |
491 | let closure_kind = closure_kind_ty.to_opt_closure_kind()?; |
492 | let env_ty = match closure_kind { | |
493 | ty::ClosureKind::Fn => self.mk_imm_ref(self.mk_region(env_region), closure_ty), | |
494 | ty::ClosureKind::FnMut => self.mk_mut_ref(self.mk_region(env_region), closure_ty), | |
495 | ty::ClosureKind::FnOnce => closure_ty, | |
496 | }; | |
cdc7bbd5 | 497 | Some(env_ty) |
ff7c6d11 XL |
498 | } |
499 | ||
48663c56 | 500 | /// Returns `true` if the node pointed to by `def_id` is a `static` item. |
1b1a35ee | 501 | pub fn is_static(self, def_id: DefId) -> bool { |
48663c56 XL |
502 | self.static_mutability(def_id).is_some() |
503 | } | |
504 | ||
f9f354fc | 505 | /// Returns `true` if this is a `static` item with the `#[thread_local]` attribute. |
1b1a35ee | 506 | pub fn is_thread_local_static(self, def_id: DefId) -> bool { |
f9f354fc XL |
507 | self.codegen_fn_attrs(def_id).flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) |
508 | } | |
509 | ||
48663c56 | 510 | /// Returns `true` if the node pointed to by `def_id` is a mutable `static` item. |
1b1a35ee | 511 | pub fn is_mutable_static(self, def_id: DefId) -> bool { |
dfeec247 | 512 | self.static_mutability(def_id) == Some(hir::Mutability::Mut) |
60c5eb7d XL |
513 | } |
514 | ||
515 | /// Get the type of the pointer to the static that we use in MIR. | |
1b1a35ee | 516 | pub fn static_ptr_ty(self, def_id: DefId) -> Ty<'tcx> { |
60c5eb7d | 517 | // Make sure that any constants in the static's type are evaluated. |
dfeec247 | 518 | let static_ty = self.normalize_erasing_regions(ty::ParamEnv::empty(), self.type_of(def_id)); |
60c5eb7d | 519 | |
29967ef6 XL |
520 | // Make sure that accesses to unsafe statics end up using raw pointers. |
521 | // For thread-locals, this needs to be kept in sync with `Rvalue::ty`. | |
60c5eb7d XL |
522 | if self.is_mutable_static(def_id) { |
523 | self.mk_mut_ptr(static_ty) | |
29967ef6 XL |
524 | } else if self.is_foreign_item(def_id) { |
525 | self.mk_imm_ptr(static_ty) | |
60c5eb7d XL |
526 | } else { |
527 | self.mk_imm_ref(self.lifetimes.re_erased, static_ty) | |
528 | } | |
abe05a73 | 529 | } |
0731742a XL |
530 | |
531 | /// Expands the given impl trait type, stopping if the type is recursive. | |
532 | pub fn try_expand_impl_trait_type( | |
533 | self, | |
534 | def_id: DefId, | |
532ac7d7 | 535 | substs: SubstsRef<'tcx>, |
0731742a | 536 | ) -> Result<Ty<'tcx>, Ty<'tcx>> { |
0731742a XL |
537 | let mut visitor = OpaqueTypeExpander { |
538 | seen_opaque_tys: FxHashSet::default(), | |
e1599b0c | 539 | expanded_cache: FxHashMap::default(), |
3dfed10e | 540 | primary_def_id: Some(def_id), |
0731742a | 541 | found_recursion: false, |
3dfed10e | 542 | check_recursion: true, |
0731742a XL |
543 | tcx: self, |
544 | }; | |
3dfed10e | 545 | |
0731742a | 546 | let expanded_type = visitor.expand_opaque_ty(def_id, substs).unwrap(); |
dfeec247 | 547 | if visitor.found_recursion { Err(expanded_type) } else { Ok(expanded_type) } |
0731742a | 548 | } |
9e0c209e SL |
549 | } |
550 | ||
3dfed10e XL |
551 | struct OpaqueTypeExpander<'tcx> { |
552 | // Contains the DefIds of the opaque types that are currently being | |
553 | // expanded. When we expand an opaque type we insert the DefId of | |
554 | // that type, and when we finish expanding that type we remove the | |
555 | // its DefId. | |
556 | seen_opaque_tys: FxHashSet<DefId>, | |
557 | // Cache of all expansions we've seen so far. This is a critical | |
558 | // optimization for some large types produced by async fn trees. | |
559 | expanded_cache: FxHashMap<(DefId, SubstsRef<'tcx>), Ty<'tcx>>, | |
560 | primary_def_id: Option<DefId>, | |
561 | found_recursion: bool, | |
562 | /// Whether or not to check for recursive opaque types. | |
563 | /// This is `true` when we're explicitly checking for opaque type | |
564 | /// recursion, and 'false' otherwise to avoid unnecessary work. | |
565 | check_recursion: bool, | |
566 | tcx: TyCtxt<'tcx>, | |
567 | } | |
568 | ||
569 | impl<'tcx> OpaqueTypeExpander<'tcx> { | |
570 | fn expand_opaque_ty(&mut self, def_id: DefId, substs: SubstsRef<'tcx>) -> Option<Ty<'tcx>> { | |
571 | if self.found_recursion { | |
572 | return None; | |
573 | } | |
574 | let substs = substs.fold_with(self); | |
575 | if !self.check_recursion || self.seen_opaque_tys.insert(def_id) { | |
576 | let expanded_ty = match self.expanded_cache.get(&(def_id, substs)) { | |
577 | Some(expanded_ty) => expanded_ty, | |
578 | None => { | |
579 | let generic_ty = self.tcx.type_of(def_id); | |
580 | let concrete_ty = generic_ty.subst(self.tcx, substs); | |
581 | let expanded_ty = self.fold_ty(concrete_ty); | |
582 | self.expanded_cache.insert((def_id, substs), expanded_ty); | |
583 | expanded_ty | |
584 | } | |
585 | }; | |
586 | if self.check_recursion { | |
587 | self.seen_opaque_tys.remove(&def_id); | |
588 | } | |
589 | Some(expanded_ty) | |
590 | } else { | |
591 | // If another opaque type that we contain is recursive, then it | |
592 | // will report the error, so we don't have to. | |
593 | self.found_recursion = def_id == *self.primary_def_id.as_ref().unwrap(); | |
594 | None | |
595 | } | |
596 | } | |
597 | } | |
598 | ||
599 | impl<'tcx> TypeFolder<'tcx> for OpaqueTypeExpander<'tcx> { | |
600 | fn tcx(&self) -> TyCtxt<'tcx> { | |
601 | self.tcx | |
602 | } | |
603 | ||
604 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
605 | if let ty::Opaque(def_id, substs) = t.kind { | |
606 | self.expand_opaque_ty(def_id, substs).unwrap_or(t) | |
607 | } else if t.has_opaque_types() { | |
608 | t.super_fold_with(self) | |
609 | } else { | |
610 | t | |
611 | } | |
612 | } | |
613 | } | |
614 | ||
dc9dc135 | 615 | impl<'tcx> ty::TyS<'tcx> { |
dfeec247 XL |
616 | /// Returns the maximum value for the given numeric type (including `char`s) |
617 | /// or returns `None` if the type is not numeric. | |
618 | pub fn numeric_max_val(&'tcx self, tcx: TyCtxt<'tcx>) -> Option<&'tcx ty::Const<'tcx>> { | |
1b1a35ee | 619 | let val = match self.kind() { |
dfeec247 XL |
620 | ty::Int(_) | ty::Uint(_) => { |
621 | let (size, signed) = int_size_and_signed(tcx, self); | |
622 | let val = if signed { signed_max(size) as u128 } else { unsigned_max(size) }; | |
623 | Some(val) | |
624 | } | |
625 | ty::Char => Some(std::char::MAX as u128), | |
626 | ty::Float(fty) => Some(match fty { | |
5869c6ff XL |
627 | ty::FloatTy::F32 => rustc_apfloat::ieee::Single::INFINITY.to_bits(), |
628 | ty::FloatTy::F64 => rustc_apfloat::ieee::Double::INFINITY.to_bits(), | |
dfeec247 XL |
629 | }), |
630 | _ => None, | |
631 | }; | |
632 | val.map(|v| ty::Const::from_bits(tcx, v, ty::ParamEnv::empty().and(self))) | |
633 | } | |
634 | ||
635 | /// Returns the minimum value for the given numeric type (including `char`s) | |
636 | /// or returns `None` if the type is not numeric. | |
637 | pub fn numeric_min_val(&'tcx self, tcx: TyCtxt<'tcx>) -> Option<&'tcx ty::Const<'tcx>> { | |
1b1a35ee | 638 | let val = match self.kind() { |
dfeec247 XL |
639 | ty::Int(_) | ty::Uint(_) => { |
640 | let (size, signed) = int_size_and_signed(tcx, self); | |
29967ef6 | 641 | let val = if signed { size.truncate(signed_min(size) as u128) } else { 0 }; |
dfeec247 XL |
642 | Some(val) |
643 | } | |
644 | ty::Char => Some(0), | |
645 | ty::Float(fty) => Some(match fty { | |
5869c6ff XL |
646 | ty::FloatTy::F32 => (-::rustc_apfloat::ieee::Single::INFINITY).to_bits(), |
647 | ty::FloatTy::F64 => (-::rustc_apfloat::ieee::Double::INFINITY).to_bits(), | |
dfeec247 XL |
648 | }), |
649 | _ => None, | |
650 | }; | |
651 | val.map(|v| ty::Const::from_bits(tcx, v, ty::ParamEnv::empty().and(self))) | |
652 | } | |
653 | ||
0731742a XL |
654 | /// Checks whether values of this type `T` are *moved* or *copied* |
655 | /// when referenced -- this amounts to a check for whether `T: | |
656 | /// Copy`, but note that we **don't** consider lifetimes when | |
657 | /// doing this check. This means that we may generate MIR which | |
658 | /// does copies even when the type actually doesn't satisfy the | |
659 | /// full requirements for the `Copy` trait (cc #29149) -- this | |
660 | /// winds up being reported as an error during NLL borrow check. | |
dc9dc135 XL |
661 | pub fn is_copy_modulo_regions( |
662 | &'tcx self, | |
f035d41b | 663 | tcx_at: TyCtxtAt<'tcx>, |
dc9dc135 | 664 | param_env: ty::ParamEnv<'tcx>, |
dc9dc135 | 665 | ) -> bool { |
f035d41b | 666 | tcx_at.is_copy_raw(param_env.and(self)) |
e9174d1e SL |
667 | } |
668 | ||
0731742a XL |
669 | /// Checks whether values of this type `T` have a size known at |
670 | /// compile time (i.e., whether `T: Sized`). Lifetimes are ignored | |
671 | /// for the purposes of this check, so it can be an | |
672 | /// over-approximation in generic contexts, where one can have | |
673 | /// strange rules like `<T as Foo<'static>>::Bar: Sized` that | |
674 | /// actually carry lifetime requirements. | |
dc9dc135 | 675 | pub fn is_sized(&'tcx self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { |
74b04a01 | 676 | self.is_trivially_sized(tcx_at.tcx) || tcx_at.is_sized_raw(param_env.and(self)) |
e9174d1e SL |
677 | } |
678 | ||
0731742a XL |
679 | /// Checks whether values of this type `T` implement the `Freeze` |
680 | /// trait -- frozen types are those that do not contain a | |
9fa01778 | 681 | /// `UnsafeCell` anywhere. This is a language concept used to |
0731742a XL |
682 | /// distinguish "true immutability", which is relevant to |
683 | /// optimization as well as the rules around static values. Note | |
684 | /// that the `Freeze` trait is not exposed to end users and is | |
685 | /// effectively an implementation detail. | |
f035d41b XL |
686 | pub fn is_freeze(&'tcx self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { |
687 | self.is_trivially_freeze() || tcx_at.is_freeze_raw(param_env.and(self)) | |
74b04a01 XL |
688 | } |
689 | ||
690 | /// Fast path helper for testing if a type is `Freeze`. | |
691 | /// | |
692 | /// Returning true means the type is known to be `Freeze`. Returning | |
693 | /// `false` means nothing -- could be `Freeze`, might not be. | |
694 | fn is_trivially_freeze(&self) -> bool { | |
1b1a35ee | 695 | match self.kind() { |
74b04a01 XL |
696 | ty::Int(_) |
697 | | ty::Uint(_) | |
698 | | ty::Float(_) | |
699 | | ty::Bool | |
700 | | ty::Char | |
701 | | ty::Str | |
702 | | ty::Never | |
703 | | ty::Ref(..) | |
704 | | ty::RawPtr(_) | |
705 | | ty::FnDef(..) | |
f035d41b | 706 | | ty::Error(_) |
74b04a01 XL |
707 | | ty::FnPtr(_) => true, |
708 | ty::Tuple(_) => self.tuple_fields().all(Self::is_trivially_freeze), | |
709 | ty::Slice(elem_ty) | ty::Array(elem_ty, _) => elem_ty.is_trivially_freeze(), | |
710 | ty::Adt(..) | |
711 | | ty::Bound(..) | |
712 | | ty::Closure(..) | |
713 | | ty::Dynamic(..) | |
714 | | ty::Foreign(_) | |
715 | | ty::Generator(..) | |
716 | | ty::GeneratorWitness(_) | |
717 | | ty::Infer(_) | |
718 | | ty::Opaque(..) | |
719 | | ty::Param(_) | |
720 | | ty::Placeholder(_) | |
f9f354fc | 721 | | ty::Projection(_) => false, |
74b04a01 | 722 | } |
cc61c64b XL |
723 | } |
724 | ||
cdc7bbd5 XL |
725 | /// Checks whether values of this type `T` implement the `Unpin` trait. |
726 | pub fn is_unpin(&'tcx self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { | |
727 | self.is_trivially_unpin() || tcx_at.is_unpin_raw(param_env.and(self)) | |
728 | } | |
729 | ||
730 | /// Fast path helper for testing if a type is `Unpin`. | |
731 | /// | |
732 | /// Returning true means the type is known to be `Unpin`. Returning | |
733 | /// `false` means nothing -- could be `Unpin`, might not be. | |
734 | fn is_trivially_unpin(&self) -> bool { | |
735 | match self.kind() { | |
736 | ty::Int(_) | |
737 | | ty::Uint(_) | |
738 | | ty::Float(_) | |
739 | | ty::Bool | |
740 | | ty::Char | |
741 | | ty::Str | |
742 | | ty::Never | |
743 | | ty::Ref(..) | |
744 | | ty::RawPtr(_) | |
745 | | ty::FnDef(..) | |
746 | | ty::Error(_) | |
747 | | ty::FnPtr(_) => true, | |
748 | ty::Tuple(_) => self.tuple_fields().all(Self::is_trivially_unpin), | |
749 | ty::Slice(elem_ty) | ty::Array(elem_ty, _) => elem_ty.is_trivially_unpin(), | |
750 | ty::Adt(..) | |
751 | | ty::Bound(..) | |
752 | | ty::Closure(..) | |
753 | | ty::Dynamic(..) | |
754 | | ty::Foreign(_) | |
755 | | ty::Generator(..) | |
756 | | ty::GeneratorWitness(_) | |
757 | | ty::Infer(_) | |
758 | | ty::Opaque(..) | |
759 | | ty::Param(_) | |
760 | | ty::Placeholder(_) | |
761 | | ty::Projection(_) => false, | |
762 | } | |
763 | } | |
764 | ||
cc61c64b XL |
765 | /// If `ty.needs_drop(...)` returns `true`, then `ty` is definitely |
766 | /// non-copy and *might* have a destructor attached; if it returns | |
0731742a | 767 | /// `false`, then `ty` definitely has no destructor (i.e., no drop glue). |
cc61c64b XL |
768 | /// |
769 | /// (Note that this implies that if `ty` has a destructor attached, | |
770 | /// then `needs_drop` will definitely return `true` for `ty`.) | |
e74abb32 XL |
771 | /// |
772 | /// Note that this method is used to check eligible types in unions. | |
cc61c64b | 773 | #[inline] |
dc9dc135 | 774 | pub fn needs_drop(&'tcx self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { |
74b04a01 XL |
775 | // Avoid querying in simple cases. |
776 | match needs_drop_components(self, &tcx.data_layout) { | |
777 | Err(AlwaysRequiresDrop) => true, | |
778 | Ok(components) => { | |
779 | let query_ty = match *components { | |
780 | [] => return false, | |
781 | // If we've got a single component, call the query with that | |
782 | // to increase the chance that we hit the query cache. | |
783 | [component_ty] => component_ty, | |
784 | _ => self, | |
785 | }; | |
786 | // This doesn't depend on regions, so try to minimize distinct | |
787 | // query keys used. | |
788 | let erased = tcx.normalize_erasing_regions(param_env, query_ty); | |
789 | tcx.needs_drop_raw(param_env.and(erased)) | |
790 | } | |
791 | } | |
cc61c64b XL |
792 | } |
793 | ||
17df50a5 XL |
794 | /// Checks if `ty` has has a significant drop. |
795 | /// | |
796 | /// Note that this method can return false even if `ty` has a destructor | |
797 | /// attached; even if that is the case then the adt has been marked with | |
798 | /// the attribute `rustc_insignificant_dtor`. | |
799 | /// | |
800 | /// Note that this method is used to check for change in drop order for | |
801 | /// 2229 drop reorder migration analysis. | |
802 | #[inline] | |
803 | pub fn has_significant_drop( | |
804 | &'tcx self, | |
805 | tcx: TyCtxt<'tcx>, | |
806 | param_env: ty::ParamEnv<'tcx>, | |
807 | ) -> bool { | |
808 | // Avoid querying in simple cases. | |
809 | match needs_drop_components(self, &tcx.data_layout) { | |
810 | Err(AlwaysRequiresDrop) => true, | |
811 | Ok(components) => { | |
812 | let query_ty = match *components { | |
813 | [] => return false, | |
814 | // If we've got a single component, call the query with that | |
815 | // to increase the chance that we hit the query cache. | |
816 | [component_ty] => component_ty, | |
817 | _ => self, | |
818 | }; | |
819 | // This doesn't depend on regions, so try to minimize distinct | |
820 | // query keys used. | |
821 | let erased = tcx.normalize_erasing_regions(param_env, query_ty); | |
822 | tcx.has_significant_drop_raw(param_env.and(erased)) | |
823 | } | |
824 | } | |
825 | } | |
826 | ||
f035d41b XL |
827 | /// Returns `true` if equality for this type is both reflexive and structural. |
828 | /// | |
829 | /// Reflexive equality for a type is indicated by an `Eq` impl for that type. | |
830 | /// | |
831 | /// Primitive types (`u32`, `str`) have structural equality by definition. For composite data | |
832 | /// types, equality for the type as a whole is structural when it is the same as equality | |
833 | /// between all components (fields, array elements, etc.) of that type. For ADTs, structural | |
834 | /// equality is indicated by an implementation of `PartialStructuralEq` and `StructuralEq` for | |
835 | /// that type. | |
836 | /// | |
837 | /// This function is "shallow" because it may return `true` for a composite type whose fields | |
838 | /// are not `StructuralEq`. For example, `[T; 4]` has structural equality regardless of `T` | |
839 | /// because equality for arrays is determined by the equality of each array element. If you | |
840 | /// want to know whether a given call to `PartialEq::eq` will proceed structurally all the way | |
841 | /// down, you will need to use a type visitor. | |
842 | #[inline] | |
843 | pub fn is_structural_eq_shallow(&'tcx self, tcx: TyCtxt<'tcx>) -> bool { | |
1b1a35ee | 844 | match self.kind() { |
f035d41b XL |
845 | // Look for an impl of both `PartialStructuralEq` and `StructuralEq`. |
846 | Adt(..) => tcx.has_structural_eq_impls(self), | |
847 | ||
848 | // Primitive types that satisfy `Eq`. | |
849 | Bool | Char | Int(_) | Uint(_) | Str | Never => true, | |
850 | ||
851 | // Composite types that satisfy `Eq` when all of their fields do. | |
852 | // | |
853 | // Because this function is "shallow", we return `true` for these composites regardless | |
854 | // of the type(s) contained within. | |
855 | Ref(..) | Array(..) | Slice(_) | Tuple(..) => true, | |
856 | ||
857 | // Raw pointers use bitwise comparison. | |
858 | RawPtr(_) | FnPtr(_) => true, | |
859 | ||
860 | // Floating point numbers are not `Eq`. | |
861 | Float(_) => false, | |
862 | ||
863 | // Conservatively return `false` for all others... | |
864 | ||
865 | // Anonymous function types | |
866 | FnDef(..) | Closure(..) | Dynamic(..) | Generator(..) => false, | |
867 | ||
868 | // Generic or inferred types | |
869 | // | |
870 | // FIXME(ecstaticmorse): Maybe we should `bug` here? This should probably only be | |
871 | // called for known, fully-monomorphized types. | |
872 | Projection(_) | Opaque(..) | Param(_) | Bound(..) | Placeholder(_) | Infer(_) => false, | |
873 | ||
874 | Foreign(_) | GeneratorWitness(..) | Error(_) => false, | |
875 | } | |
876 | } | |
877 | ||
0731742a | 878 | pub fn same_type(a: Ty<'tcx>, b: Ty<'tcx>) -> bool { |
1b1a35ee | 879 | match (&a.kind(), &b.kind()) { |
0731742a XL |
880 | (&Adt(did_a, substs_a), &Adt(did_b, substs_b)) => { |
881 | if did_a != did_b { | |
882 | return false; | |
883 | } | |
884 | ||
885 | substs_a.types().zip(substs_b.types()).all(|(a, b)| Self::same_type(a, b)) | |
886 | } | |
887 | _ => a == b, | |
888 | } | |
889 | } | |
890 | ||
e1599b0c XL |
891 | /// Peel off all reference types in this type until there are none left. |
892 | /// | |
893 | /// This method is idempotent, i.e. `ty.peel_refs().peel_refs() == ty.peel_refs()`. | |
894 | /// | |
895 | /// # Examples | |
896 | /// | |
897 | /// - `u8` -> `u8` | |
898 | /// - `&'a mut u8` -> `u8` | |
899 | /// - `&'a &'b u8` -> `u8` | |
900 | /// - `&'a *const &'b u8 -> *const &'b u8` | |
901 | pub fn peel_refs(&'tcx self) -> Ty<'tcx> { | |
902 | let mut ty = self; | |
1b1a35ee | 903 | while let Ref(_, inner_ty, _) = ty.kind() { |
e1599b0c XL |
904 | ty = inner_ty; |
905 | } | |
906 | ty | |
907 | } | |
e9174d1e | 908 | } |
7cac9316 | 909 | |
abe05a73 XL |
910 | pub enum ExplicitSelf<'tcx> { |
911 | ByValue, | |
912 | ByReference(ty::Region<'tcx>, hir::Mutability), | |
ff7c6d11 | 913 | ByRawPointer(hir::Mutability), |
abe05a73 | 914 | ByBox, |
dfeec247 | 915 | Other, |
abe05a73 XL |
916 | } |
917 | ||
918 | impl<'tcx> ExplicitSelf<'tcx> { | |
919 | /// Categorizes an explicit self declaration like `self: SomeType` | |
920 | /// into either `self`, `&self`, `&mut self`, `Box<self>`, or | |
921 | /// `Other`. | |
922 | /// This is mainly used to require the arbitrary_self_types feature | |
923 | /// in the case of `Other`, to improve error messages in the common cases, | |
924 | /// and to make `Other` non-object-safe. | |
925 | /// | |
926 | /// Examples: | |
927 | /// | |
928 | /// ``` | |
929 | /// impl<'a> Foo for &'a T { | |
930 | /// // Legal declarations: | |
931 | /// fn method1(self: &&'a T); // ExplicitSelf::ByReference | |
932 | /// fn method2(self: &'a T); // ExplicitSelf::ByValue | |
933 | /// fn method3(self: Box<&'a T>); // ExplicitSelf::ByBox | |
934 | /// fn method4(self: Rc<&'a T>); // ExplicitSelf::Other | |
935 | /// | |
936 | /// // Invalid cases will be caught by `check_method_receiver`: | |
937 | /// fn method_err1(self: &'a mut T); // ExplicitSelf::Other | |
938 | /// fn method_err2(self: &'static T) // ExplicitSelf::ByValue | |
939 | /// fn method_err3(self: &&T) // ExplicitSelf::ByReference | |
940 | /// } | |
941 | /// ``` | |
942 | /// | |
dfeec247 | 943 | pub fn determine<P>(self_arg_ty: Ty<'tcx>, is_self_ty: P) -> ExplicitSelf<'tcx> |
abe05a73 | 944 | where |
dfeec247 | 945 | P: Fn(Ty<'tcx>) -> bool, |
abe05a73 XL |
946 | { |
947 | use self::ExplicitSelf::*; | |
948 | ||
1b1a35ee | 949 | match *self_arg_ty.kind() { |
abe05a73 | 950 | _ if is_self_ty(self_arg_ty) => ByValue, |
dfeec247 XL |
951 | ty::Ref(region, ty, mutbl) if is_self_ty(ty) => ByReference(region, mutbl), |
952 | ty::RawPtr(ty::TypeAndMut { ty, mutbl }) if is_self_ty(ty) => ByRawPointer(mutbl), | |
953 | ty::Adt(def, _) if def.is_box() && is_self_ty(self_arg_ty.boxed_ty()) => ByBox, | |
954 | _ => Other, | |
abe05a73 XL |
955 | } |
956 | } | |
957 | } | |
74b04a01 XL |
958 | |
959 | /// Returns a list of types such that the given type needs drop if and only if | |
960 | /// *any* of the returned types need drop. Returns `Err(AlwaysRequiresDrop)` if | |
961 | /// this type always needs drop. | |
962 | pub fn needs_drop_components( | |
963 | ty: Ty<'tcx>, | |
964 | target_layout: &TargetDataLayout, | |
965 | ) -> Result<SmallVec<[Ty<'tcx>; 2]>, AlwaysRequiresDrop> { | |
1b1a35ee | 966 | match ty.kind() { |
74b04a01 XL |
967 | ty::Infer(ty::FreshIntTy(_)) |
968 | | ty::Infer(ty::FreshFloatTy(_)) | |
969 | | ty::Bool | |
970 | | ty::Int(_) | |
971 | | ty::Uint(_) | |
972 | | ty::Float(_) | |
973 | | ty::Never | |
974 | | ty::FnDef(..) | |
975 | | ty::FnPtr(_) | |
976 | | ty::Char | |
977 | | ty::GeneratorWitness(..) | |
978 | | ty::RawPtr(_) | |
979 | | ty::Ref(..) | |
980 | | ty::Str => Ok(SmallVec::new()), | |
981 | ||
982 | // Foreign types can never have destructors. | |
983 | ty::Foreign(..) => Ok(SmallVec::new()), | |
984 | ||
f035d41b | 985 | ty::Dynamic(..) | ty::Error(_) => Err(AlwaysRequiresDrop), |
74b04a01 XL |
986 | |
987 | ty::Slice(ty) => needs_drop_components(ty, target_layout), | |
988 | ty::Array(elem_ty, size) => { | |
989 | match needs_drop_components(elem_ty, target_layout) { | |
990 | Ok(v) if v.is_empty() => Ok(v), | |
991 | res => match size.val.try_to_bits(target_layout.pointer_size) { | |
992 | // Arrays of size zero don't need drop, even if their element | |
993 | // type does. | |
994 | Some(0) => Ok(SmallVec::new()), | |
995 | Some(_) => res, | |
996 | // We don't know which of the cases above we are in, so | |
997 | // return the whole type and let the caller decide what to | |
998 | // do. | |
999 | None => Ok(smallvec![ty]), | |
1000 | }, | |
1001 | } | |
1002 | } | |
1003 | // If any field needs drop, then the whole tuple does. | |
1004 | ty::Tuple(..) => ty.tuple_fields().try_fold(SmallVec::new(), move |mut acc, elem| { | |
1005 | acc.extend(needs_drop_components(elem, target_layout)?); | |
1006 | Ok(acc) | |
1007 | }), | |
1008 | ||
1009 | // These require checking for `Copy` bounds or `Adt` destructors. | |
1010 | ty::Adt(..) | |
1011 | | ty::Projection(..) | |
74b04a01 XL |
1012 | | ty::Param(_) |
1013 | | ty::Bound(..) | |
1014 | | ty::Placeholder(..) | |
1015 | | ty::Opaque(..) | |
1016 | | ty::Infer(_) | |
ba9703b0 XL |
1017 | | ty::Closure(..) |
1018 | | ty::Generator(..) => Ok(smallvec![ty]), | |
74b04a01 XL |
1019 | } |
1020 | } | |
1021 | ||
fc512014 XL |
1022 | // Does the equivalent of |
1023 | // ``` | |
1024 | // let v = self.iter().map(|p| p.fold_with(folder)).collect::<SmallVec<[_; 8]>>(); | |
1025 | // folder.tcx().intern_*(&v) | |
1026 | // ``` | |
1027 | pub fn fold_list<'tcx, F, T>( | |
1028 | list: &'tcx ty::List<T>, | |
1029 | folder: &mut F, | |
1030 | intern: impl FnOnce(TyCtxt<'tcx>, &[T]) -> &'tcx ty::List<T>, | |
1031 | ) -> &'tcx ty::List<T> | |
1032 | where | |
1033 | F: TypeFolder<'tcx>, | |
1034 | T: TypeFoldable<'tcx> + PartialEq + Copy, | |
1035 | { | |
1036 | let mut iter = list.iter(); | |
1037 | // Look for the first element that changed | |
1038 | if let Some((i, new_t)) = iter.by_ref().enumerate().find_map(|(i, t)| { | |
1039 | let new_t = t.fold_with(folder); | |
1040 | if new_t == t { None } else { Some((i, new_t)) } | |
1041 | }) { | |
1042 | // An element changed, prepare to intern the resulting list | |
1043 | let mut new_list = SmallVec::<[_; 8]>::with_capacity(list.len()); | |
1044 | new_list.extend_from_slice(&list[..i]); | |
1045 | new_list.push(new_t); | |
1046 | new_list.extend(iter.map(|t| t.fold_with(folder))); | |
1047 | intern(folder.tcx(), &new_list) | |
1048 | } else { | |
1049 | list | |
1050 | } | |
1051 | } | |
1052 | ||
3dfed10e | 1053 | #[derive(Copy, Clone, Debug, HashStable, TyEncodable, TyDecodable)] |
74b04a01 | 1054 | pub struct AlwaysRequiresDrop; |
3dfed10e XL |
1055 | |
1056 | /// Normalizes all opaque types in the given value, replacing them | |
1057 | /// with their underlying types. | |
1058 | pub fn normalize_opaque_types( | |
1059 | tcx: TyCtxt<'tcx>, | |
1060 | val: &'tcx List<ty::Predicate<'tcx>>, | |
1061 | ) -> &'tcx List<ty::Predicate<'tcx>> { | |
1062 | let mut visitor = OpaqueTypeExpander { | |
1063 | seen_opaque_tys: FxHashSet::default(), | |
1064 | expanded_cache: FxHashMap::default(), | |
1065 | primary_def_id: None, | |
1066 | found_recursion: false, | |
1067 | check_recursion: false, | |
1068 | tcx, | |
1069 | }; | |
1070 | val.fold_with(&mut visitor) | |
1071 | } | |
1072 | ||
1073 | pub fn provide(providers: &mut ty::query::Providers) { | |
1074 | *providers = ty::query::Providers { normalize_opaque_types, ..*providers } | |
1075 | } |