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Commit | Line | Data |
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add651ee | 1 | // Generic arguments. |
970d7e83 | 2 | |
3dfed10e | 3 | use crate::ty::codec::{TyDecoder, TyEncoder}; |
064997fb | 4 | use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable}; |
add651ee | 5 | use crate::ty::sty::{ClosureArgs, GeneratorArgs, InlineConstArgs}; |
9ffffee4 | 6 | use crate::ty::visit::{TypeVisitable, TypeVisitableExt, TypeVisitor}; |
923072b8 | 7 | use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt}; |
970d7e83 | 8 | |
487cf647 | 9 | use rustc_data_structures::intern::Interned; |
9c376795 | 10 | use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg}; |
dfeec247 | 11 | use rustc_hir::def_id::DefId; |
532ac7d7 | 12 | use rustc_macros::HashStable; |
3dfed10e | 13 | use rustc_serialize::{self, Decodable, Encodable}; |
fe692bf9 | 14 | use rustc_span::sym; |
487cf647 | 15 | use rustc_type_ir::WithCachedTypeInfo; |
dfeec247 | 16 | use smallvec::SmallVec; |
1a4d82fc | 17 | |
0531ce1d | 18 | use core::intrinsics; |
532ac7d7 | 19 | use std::cmp::Ordering; |
9e0c209e SL |
20 | use std::marker::PhantomData; |
21 | use std::mem; | |
0531ce1d | 22 | use std::num::NonZeroUsize; |
487cf647 | 23 | use std::ops::{ControlFlow, Deref}; |
9e0c209e | 24 | |
a1dfa0c6 | 25 | /// An entity in the Rust type system, which can be one of |
532ac7d7 | 26 | /// several kinds (types, lifetimes, and consts). |
94222f64 | 27 | /// To reduce memory usage, a `GenericArg` is an interned pointer, |
9e0c209e | 28 | /// with the lowest 2 bits being reserved for a tag to |
532ac7d7 | 29 | /// indicate the type (`Ty`, `Region`, or `Const`) it points to. |
5099ac24 FG |
30 | /// |
31 | /// Note: the `PartialEq`, `Eq` and `Hash` derives are only valid because `Ty`, | |
32 | /// `Region` and `Const` are all interned. | |
0531ce1d | 33 | #[derive(Copy, Clone, PartialEq, Eq, Hash)] |
e74abb32 | 34 | pub struct GenericArg<'tcx> { |
0531ce1d | 35 | ptr: NonZeroUsize, |
5099ac24 | 36 | marker: PhantomData<(Ty<'tcx>, ty::Region<'tcx>, ty::Const<'tcx>)>, |
970d7e83 LB |
37 | } |
38 | ||
9c376795 FG |
39 | impl<'tcx> IntoDiagnosticArg for GenericArg<'tcx> { |
40 | fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> { | |
41 | self.to_string().into_diagnostic_arg() | |
42 | } | |
43 | } | |
44 | ||
9e0c209e SL |
45 | const TAG_MASK: usize = 0b11; |
46 | const TYPE_TAG: usize = 0b00; | |
47 | const REGION_TAG: usize = 0b01; | |
532ac7d7 | 48 | const CONST_TAG: usize = 0b10; |
9e0c209e | 49 | |
49aad941 | 50 | #[derive(Debug, TyEncodable, TyDecodable, PartialEq, Eq, PartialOrd, Ord, HashStable)] |
e74abb32 | 51 | pub enum GenericArgKind<'tcx> { |
0531ce1d XL |
52 | Lifetime(ty::Region<'tcx>), |
53 | Type(Ty<'tcx>), | |
5099ac24 | 54 | Const(ty::Const<'tcx>), |
0531ce1d XL |
55 | } |
56 | ||
e74abb32 | 57 | impl<'tcx> GenericArgKind<'tcx> { |
5099ac24 | 58 | #[inline] |
e74abb32 | 59 | fn pack(self) -> GenericArg<'tcx> { |
0531ce1d | 60 | let (tag, ptr) = match self { |
e74abb32 | 61 | GenericArgKind::Lifetime(lt) => { |
0531ce1d | 62 | // Ensure we can use the tag bits. |
923072b8 FG |
63 | assert_eq!(mem::align_of_val(&*lt.0.0) & TAG_MASK, 0); |
64 | (REGION_TAG, lt.0.0 as *const ty::RegionKind<'tcx> as usize) | |
0531ce1d | 65 | } |
e74abb32 | 66 | GenericArgKind::Type(ty) => { |
0531ce1d | 67 | // Ensure we can use the tag bits. |
923072b8 | 68 | assert_eq!(mem::align_of_val(&*ty.0.0) & TAG_MASK, 0); |
487cf647 | 69 | (TYPE_TAG, ty.0.0 as *const WithCachedTypeInfo<ty::TyKind<'tcx>> as usize) |
0531ce1d | 70 | } |
e74abb32 | 71 | GenericArgKind::Const(ct) => { |
532ac7d7 | 72 | // Ensure we can use the tag bits. |
923072b8 | 73 | assert_eq!(mem::align_of_val(&*ct.0.0) & TAG_MASK, 0); |
9c376795 | 74 | (CONST_TAG, ct.0.0 as *const ty::ConstData<'tcx> as usize) |
532ac7d7 | 75 | } |
0531ce1d | 76 | }; |
9e0c209e | 77 | |
dfeec247 | 78 | GenericArg { ptr: unsafe { NonZeroUsize::new_unchecked(ptr | tag) }, marker: PhantomData } |
1a4d82fc | 79 | } |
9cc50fc6 SL |
80 | } |
81 | ||
e74abb32 | 82 | impl<'tcx> Ord for GenericArg<'tcx> { |
923072b8 | 83 | fn cmp(&self, other: &GenericArg<'tcx>) -> Ordering { |
b7449926 | 84 | self.unpack().cmp(&other.unpack()) |
94b46f34 XL |
85 | } |
86 | } | |
87 | ||
e74abb32 | 88 | impl<'tcx> PartialOrd for GenericArg<'tcx> { |
923072b8 | 89 | fn partial_cmp(&self, other: &GenericArg<'tcx>) -> Option<Ordering> { |
94b46f34 XL |
90 | Some(self.cmp(&other)) |
91 | } | |
92 | } | |
93 | ||
e74abb32 | 94 | impl<'tcx> From<ty::Region<'tcx>> for GenericArg<'tcx> { |
5099ac24 | 95 | #[inline] |
e74abb32 XL |
96 | fn from(r: ty::Region<'tcx>) -> GenericArg<'tcx> { |
97 | GenericArgKind::Lifetime(r).pack() | |
0531ce1d XL |
98 | } |
99 | } | |
9e0c209e | 100 | |
e74abb32 | 101 | impl<'tcx> From<Ty<'tcx>> for GenericArg<'tcx> { |
5099ac24 | 102 | #[inline] |
e74abb32 XL |
103 | fn from(ty: Ty<'tcx>) -> GenericArg<'tcx> { |
104 | GenericArgKind::Type(ty).pack() | |
970d7e83 LB |
105 | } |
106 | } | |
107 | ||
5099ac24 FG |
108 | impl<'tcx> From<ty::Const<'tcx>> for GenericArg<'tcx> { |
109 | #[inline] | |
110 | fn from(c: ty::Const<'tcx>) -> GenericArg<'tcx> { | |
e74abb32 | 111 | GenericArgKind::Const(c).pack() |
532ac7d7 XL |
112 | } |
113 | } | |
114 | ||
487cf647 FG |
115 | impl<'tcx> From<ty::Term<'tcx>> for GenericArg<'tcx> { |
116 | fn from(value: ty::Term<'tcx>) -> Self { | |
117 | match value.unpack() { | |
118 | ty::TermKind::Ty(t) => t.into(), | |
119 | ty::TermKind::Const(c) => c.into(), | |
120 | } | |
121 | } | |
122 | } | |
123 | ||
e74abb32 | 124 | impl<'tcx> GenericArg<'tcx> { |
9e0c209e | 125 | #[inline] |
e74abb32 | 126 | pub fn unpack(self) -> GenericArgKind<'tcx> { |
7cac9316 | 127 | let ptr = self.ptr.get(); |
5099ac24 FG |
128 | // SAFETY: use of `Interned::new_unchecked` here is ok because these |
129 | // pointers were originally created from `Interned` types in `pack()`, | |
130 | // and this is just going in the other direction. | |
9e0c209e | 131 | unsafe { |
0531ce1d | 132 | match ptr & TAG_MASK { |
5099ac24 | 133 | REGION_TAG => GenericArgKind::Lifetime(ty::Region(Interned::new_unchecked( |
923072b8 | 134 | &*((ptr & !TAG_MASK) as *const ty::RegionKind<'tcx>), |
5099ac24 FG |
135 | ))), |
136 | TYPE_TAG => GenericArgKind::Type(Ty(Interned::new_unchecked( | |
487cf647 | 137 | &*((ptr & !TAG_MASK) as *const WithCachedTypeInfo<ty::TyKind<'tcx>>), |
5099ac24 FG |
138 | ))), |
139 | CONST_TAG => GenericArgKind::Const(ty::Const(Interned::new_unchecked( | |
9c376795 | 140 | &*((ptr & !TAG_MASK) as *const ty::ConstData<'tcx>), |
5099ac24 | 141 | ))), |
dfeec247 | 142 | _ => intrinsics::unreachable(), |
0531ce1d | 143 | } |
1a4d82fc JJ |
144 | } |
145 | } | |
48663c56 | 146 | |
49aad941 FG |
147 | #[inline] |
148 | pub fn as_type(self) -> Option<Ty<'tcx>> { | |
064997fb | 149 | match self.unpack() { |
49aad941 FG |
150 | GenericArgKind::Type(ty) => Some(ty), |
151 | _ => None, | |
064997fb FG |
152 | } |
153 | } | |
154 | ||
49aad941 FG |
155 | #[inline] |
156 | pub fn as_region(self) -> Option<ty::Region<'tcx>> { | |
157 | match self.unpack() { | |
158 | GenericArgKind::Lifetime(re) => Some(re), | |
159 | _ => None, | |
160 | } | |
161 | } | |
162 | ||
163 | #[inline] | |
164 | pub fn as_const(self) -> Option<ty::Const<'tcx>> { | |
165 | match self.unpack() { | |
166 | GenericArgKind::Const(ct) => Some(ct), | |
167 | _ => None, | |
168 | } | |
169 | } | |
170 | ||
171 | /// Unpack the `GenericArg` as a region when it is known certainly to be a region. | |
172 | pub fn expect_region(self) -> ty::Region<'tcx> { | |
173 | self.as_region().unwrap_or_else(|| bug!("expected a region, but found another kind")) | |
174 | } | |
175 | ||
e74abb32 | 176 | /// Unpack the `GenericArg` as a type when it is known certainly to be a type. |
add651ee | 177 | /// This is true in cases where `GenericArgs` is used in places where the kinds are known |
48663c56 XL |
178 | /// to be limited (e.g. in tuples, where the only parameters are type parameters). |
179 | pub fn expect_ty(self) -> Ty<'tcx> { | |
49aad941 | 180 | self.as_type().unwrap_or_else(|| bug!("expected a type, but found another kind")) |
48663c56 | 181 | } |
ba9703b0 XL |
182 | |
183 | /// Unpack the `GenericArg` as a const when it is known certainly to be a const. | |
5099ac24 | 184 | pub fn expect_const(self) -> ty::Const<'tcx> { |
49aad941 | 185 | self.as_const().unwrap_or_else(|| bug!("expected a const, but found another kind")) |
ba9703b0 | 186 | } |
2b03887a FG |
187 | |
188 | pub fn is_non_region_infer(self) -> bool { | |
189 | match self.unpack() { | |
190 | GenericArgKind::Lifetime(_) => false, | |
9c376795 | 191 | GenericArgKind::Type(ty) => ty.is_ty_or_numeric_infer(), |
2b03887a FG |
192 | GenericArgKind::Const(ct) => ct.is_ct_infer(), |
193 | } | |
194 | } | |
9e0c209e | 195 | } |
1a4d82fc | 196 | |
e74abb32 XL |
197 | impl<'a, 'tcx> Lift<'tcx> for GenericArg<'a> { |
198 | type Lifted = GenericArg<'tcx>; | |
0531ce1d | 199 | |
29967ef6 | 200 | fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> { |
0531ce1d | 201 | match self.unpack() { |
29967ef6 XL |
202 | GenericArgKind::Lifetime(lt) => tcx.lift(lt).map(|lt| lt.into()), |
203 | GenericArgKind::Type(ty) => tcx.lift(ty).map(|ty| ty.into()), | |
204 | GenericArgKind::Const(ct) => tcx.lift(ct).map(|ct| ct.into()), | |
abe05a73 XL |
205 | } |
206 | } | |
207 | } | |
208 | ||
9ffffee4 FG |
209 | impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for GenericArg<'tcx> { |
210 | fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>( | |
211 | self, | |
212 | folder: &mut F, | |
213 | ) -> Result<Self, F::Error> { | |
0531ce1d | 214 | match self.unpack() { |
a2a8927a XL |
215 | GenericArgKind::Lifetime(lt) => lt.try_fold_with(folder).map(Into::into), |
216 | GenericArgKind::Type(ty) => ty.try_fold_with(folder).map(Into::into), | |
217 | GenericArgKind::Const(ct) => ct.try_fold_with(folder).map(Into::into), | |
1a4d82fc | 218 | } |
1a4d82fc | 219 | } |
064997fb | 220 | } |
1a4d82fc | 221 | |
9ffffee4 FG |
222 | impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for GenericArg<'tcx> { |
223 | fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> { | |
0531ce1d | 224 | match self.unpack() { |
e74abb32 XL |
225 | GenericArgKind::Lifetime(lt) => lt.visit_with(visitor), |
226 | GenericArgKind::Type(ty) => ty.visit_with(visitor), | |
227 | GenericArgKind::Const(ct) => ct.visit_with(visitor), | |
1a4d82fc JJ |
228 | } |
229 | } | |
9e0c209e | 230 | } |
1a4d82fc | 231 | |
923072b8 FG |
232 | impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for GenericArg<'tcx> { |
233 | fn encode(&self, e: &mut E) { | |
94b46f34 | 234 | self.unpack().encode(e) |
1a4d82fc | 235 | } |
9e0c209e | 236 | } |
1a4d82fc | 237 | |
923072b8 | 238 | impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for GenericArg<'tcx> { |
5099ac24 FG |
239 | fn decode(d: &mut D) -> GenericArg<'tcx> { |
240 | GenericArgKind::decode(d).pack() | |
1a4d82fc | 241 | } |
9e0c209e | 242 | } |
1a4d82fc | 243 | |
add651ee FG |
244 | /// List of generic arguments that are gonna be used to replace generic parameters. |
245 | pub type GenericArgs<'tcx> = List<GenericArg<'tcx>>; | |
1a4d82fc | 246 | |
add651ee | 247 | pub type GenericArgsRef<'tcx> = &'tcx GenericArgs<'tcx>; |
532ac7d7 | 248 | |
add651ee FG |
249 | impl<'tcx> GenericArgs<'tcx> { |
250 | /// Converts generic args to a type list. | |
49aad941 FG |
251 | /// |
252 | /// # Panics | |
253 | /// | |
254 | /// If any of the generic arguments are not types. | |
255 | pub fn into_type_list(&self, tcx: TyCtxt<'tcx>) -> &'tcx List<Ty<'tcx>> { | |
256 | tcx.mk_type_list_from_iter(self.iter().map(|arg| match arg.unpack() { | |
257 | GenericArgKind::Type(ty) => ty, | |
add651ee | 258 | _ => bug!("`into_type_list` called on generic arg with non-types"), |
49aad941 | 259 | })) |
5e7ed085 FG |
260 | } |
261 | ||
add651ee FG |
262 | /// Interpret these generic args as the args of a closure type. |
263 | /// Closure args have a particular structure controlled by the | |
e74abb32 | 264 | /// compiler that encodes information like the signature and closure kind; |
add651ee FG |
265 | /// see `ty::ClosureArgs` struct for more comments. |
266 | pub fn as_closure(&'tcx self) -> ClosureArgs<'tcx> { | |
267 | ClosureArgs { args: self } | |
e74abb32 XL |
268 | } |
269 | ||
add651ee FG |
270 | /// Interpret these generic args as the args of a generator type. |
271 | /// Generator args have a particular structure controlled by the | |
e74abb32 | 272 | /// compiler that encodes information like the signature and generator kind; |
add651ee FG |
273 | /// see `ty::GeneratorArgs` struct for more comments. |
274 | pub fn as_generator(&'tcx self) -> GeneratorArgs<'tcx> { | |
275 | GeneratorArgs { args: self } | |
e74abb32 XL |
276 | } |
277 | ||
add651ee FG |
278 | /// Interpret these generic args as the args of an inline const. |
279 | /// Inline const args have a particular structure controlled by the | |
3c0e092e | 280 | /// compiler that encodes information like the inferred type; |
add651ee FG |
281 | /// see `ty::InlineConstArgs` struct for more comments. |
282 | pub fn as_inline_const(&'tcx self) -> InlineConstArgs<'tcx> { | |
283 | InlineConstArgs { args: self } | |
3c0e092e XL |
284 | } |
285 | ||
add651ee FG |
286 | /// Creates an `GenericArgs` that maps each generic parameter to itself. |
287 | pub fn identity_for_item(tcx: TyCtxt<'tcx>, def_id: impl Into<DefId>) -> GenericArgsRef<'tcx> { | |
353b0b11 | 288 | Self::for_item(tcx, def_id.into(), |param, _| tcx.mk_param_from_def(param)) |
476ff2be SL |
289 | } |
290 | ||
add651ee | 291 | /// Creates an `GenericArgs` for generic parameter definitions, |
94b46f34 | 292 | /// by calling closures to obtain each kind. |
add651ee | 293 | /// The closures get to observe the `GenericArgs` as they're |
9e0c209e | 294 | /// being built, which can be used to correctly |
add651ee FG |
295 | /// replace defaults of generic parameters. |
296 | pub fn for_item<F>(tcx: TyCtxt<'tcx>, def_id: DefId, mut mk_kind: F) -> GenericArgsRef<'tcx> | |
dc9dc135 | 297 | where |
e74abb32 | 298 | F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>, |
94b46f34 | 299 | { |
7cac9316 | 300 | let defs = tcx.generics_of(def_id); |
94b46f34 | 301 | let count = defs.count(); |
add651ee FG |
302 | let mut args = SmallVec::with_capacity(count); |
303 | Self::fill_item(&mut args, tcx, defs, &mut mk_kind); | |
304 | tcx.mk_args(&args) | |
1a4d82fc JJ |
305 | } |
306 | ||
add651ee FG |
307 | pub fn extend_to<F>( |
308 | &self, | |
309 | tcx: TyCtxt<'tcx>, | |
310 | def_id: DefId, | |
311 | mut mk_kind: F, | |
312 | ) -> GenericArgsRef<'tcx> | |
dc9dc135 | 313 | where |
e74abb32 | 314 | F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>, |
476ff2be | 315 | { |
add651ee FG |
316 | Self::for_item(tcx, def_id, |param, args| { |
317 | self.get(param.index as usize).cloned().unwrap_or_else(|| mk_kind(param, args)) | |
94b46f34 | 318 | }) |
476ff2be SL |
319 | } |
320 | ||
94222f64 | 321 | pub fn fill_item<F>( |
add651ee | 322 | args: &mut SmallVec<[GenericArg<'tcx>; 8]>, |
dc9dc135 XL |
323 | tcx: TyCtxt<'tcx>, |
324 | defs: &ty::Generics, | |
325 | mk_kind: &mut F, | |
326 | ) where | |
e74abb32 | 327 | F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>, |
94b46f34 | 328 | { |
9e0c209e | 329 | if let Some(def_id) = defs.parent { |
7cac9316 | 330 | let parent_defs = tcx.generics_of(def_id); |
add651ee | 331 | Self::fill_item(args, tcx, parent_defs, mk_kind); |
9e0c209e | 332 | } |
add651ee | 333 | Self::fill_single(args, defs, mk_kind) |
94b46f34 | 334 | } |
1a4d82fc | 335 | |
94222f64 | 336 | pub fn fill_single<F>( |
add651ee | 337 | args: &mut SmallVec<[GenericArg<'tcx>; 8]>, |
dfeec247 XL |
338 | defs: &ty::Generics, |
339 | mk_kind: &mut F, | |
340 | ) where | |
341 | F: FnMut(&ty::GenericParamDef, &[GenericArg<'tcx>]) -> GenericArg<'tcx>, | |
94b46f34 | 342 | { |
add651ee | 343 | args.reserve(defs.params.len()); |
94b46f34 | 344 | for param in &defs.params { |
add651ee FG |
345 | let kind = mk_kind(param, args); |
346 | assert_eq!(param.index as usize, args.len(), "{args:#?}, {defs:#?}"); | |
347 | args.push(kind); | |
9e0c209e | 348 | } |
1a4d82fc JJ |
349 | } |
350 | ||
add651ee | 351 | // Extend an `original_args` list to the full number of args expected by `def_id`, |
487cf647 FG |
352 | // filling in the missing parameters with error ty/ct or 'static regions. |
353 | pub fn extend_with_error( | |
354 | tcx: TyCtxt<'tcx>, | |
355 | def_id: DefId, | |
add651ee FG |
356 | original_args: &[GenericArg<'tcx>], |
357 | ) -> GenericArgsRef<'tcx> { | |
358 | ty::GenericArgs::for_item(tcx, def_id, |def, args| { | |
359 | if let Some(arg) = original_args.get(def.index as usize) { | |
360 | *arg | |
487cf647 | 361 | } else { |
add651ee | 362 | def.to_error(tcx, args) |
487cf647 FG |
363 | } |
364 | }) | |
365 | } | |
366 | ||
9e0c209e | 367 | #[inline] |
923072b8 | 368 | pub fn types(&'tcx self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'tcx { |
49aad941 | 369 | self.iter().filter_map(|k| k.as_type()) |
1a4d82fc JJ |
370 | } |
371 | ||
9e0c209e | 372 | #[inline] |
923072b8 | 373 | pub fn regions(&'tcx self) -> impl DoubleEndedIterator<Item = ty::Region<'tcx>> + 'tcx { |
49aad941 | 374 | self.iter().filter_map(|k| k.as_region()) |
970d7e83 | 375 | } |
1a4d82fc | 376 | |
532ac7d7 | 377 | #[inline] |
923072b8 | 378 | pub fn consts(&'tcx self) -> impl DoubleEndedIterator<Item = ty::Const<'tcx>> + 'tcx { |
49aad941 | 379 | self.iter().filter_map(|k| k.as_const()) |
532ac7d7 XL |
380 | } |
381 | ||
781aab86 | 382 | /// Returns generic arguments that are not lifetimes or host effect params. |
532ac7d7 XL |
383 | #[inline] |
384 | pub fn non_erasable_generics( | |
923072b8 | 385 | &'tcx self, |
781aab86 FG |
386 | tcx: TyCtxt<'tcx>, |
387 | def_id: DefId, | |
923072b8 | 388 | ) -> impl DoubleEndedIterator<Item = GenericArgKind<'tcx>> + 'tcx { |
781aab86 FG |
389 | let generics = tcx.generics_of(def_id); |
390 | self.iter().enumerate().filter_map(|(i, k)| match k.unpack() { | |
391 | _ if Some(i) == generics.host_effect_index => None, | |
392 | ty::GenericArgKind::Lifetime(_) => None, | |
dfeec247 | 393 | generic => Some(generic), |
532ac7d7 XL |
394 | }) |
395 | } | |
396 | ||
9e0c209e | 397 | #[inline] |
9c376795 | 398 | #[track_caller] |
9e0c209e | 399 | pub fn type_at(&self, i: usize) -> Ty<'tcx> { |
49aad941 | 400 | self[i].as_type().unwrap_or_else(|| bug!("expected type for param #{} in {:?}", i, self)) |
1a4d82fc | 401 | } |
1a4d82fc | 402 | |
9e0c209e | 403 | #[inline] |
9c376795 | 404 | #[track_caller] |
7cac9316 | 405 | pub fn region_at(&self, i: usize) -> ty::Region<'tcx> { |
49aad941 FG |
406 | self[i] |
407 | .as_region() | |
408 | .unwrap_or_else(|| bug!("expected region for param #{} in {:?}", i, self)) | |
1a4d82fc JJ |
409 | } |
410 | ||
532ac7d7 | 411 | #[inline] |
9c376795 | 412 | #[track_caller] |
5099ac24 | 413 | pub fn const_at(&self, i: usize) -> ty::Const<'tcx> { |
49aad941 | 414 | self[i].as_const().unwrap_or_else(|| bug!("expected const for param #{} in {:?}", i, self)) |
532ac7d7 XL |
415 | } |
416 | ||
9e0c209e | 417 | #[inline] |
9c376795 | 418 | #[track_caller] |
e74abb32 | 419 | pub fn type_for_def(&self, def: &ty::GenericParamDef) -> GenericArg<'tcx> { |
94b46f34 | 420 | self.type_at(def.index as usize).into() |
9e0c209e SL |
421 | } |
422 | ||
add651ee FG |
423 | /// Transform from generic args for a child of `source_ancestor` |
424 | /// (e.g., a trait or impl) to args for the same child | |
425 | /// in a different item, with `target_args` as the base for | |
9e0c209e | 426 | /// the target impl/trait, with the source child-specific |
0731742a | 427 | /// parameters (e.g., method parameters) on top of that base. |
f035d41b XL |
428 | /// |
429 | /// For example given: | |
430 | /// | |
431 | /// ```no_run | |
432 | /// trait X<S> { fn f<T>(); } | |
433 | /// impl<U> X<U> for U { fn f<V>() {} } | |
434 | /// ``` | |
435 | /// | |
add651ee | 436 | /// * If `self` is `[Self, S, T]`: the identity args of `f` in the trait. |
f035d41b | 437 | /// * If `source_ancestor` is the def_id of the trait. |
add651ee FG |
438 | /// * If `target_args` is `[U]`, the args for the impl. |
439 | /// * Then we will return `[U, T]`, the arg for `f` in the impl that | |
f035d41b | 440 | /// are needed for it to match the trait. |
dc9dc135 XL |
441 | pub fn rebase_onto( |
442 | &self, | |
443 | tcx: TyCtxt<'tcx>, | |
444 | source_ancestor: DefId, | |
add651ee FG |
445 | target_args: GenericArgsRef<'tcx>, |
446 | ) -> GenericArgsRef<'tcx> { | |
7cac9316 | 447 | let defs = tcx.generics_of(source_ancestor); |
781aab86 | 448 | tcx.mk_args_from_iter(target_args.iter().chain(self.iter().skip(defs.count()))) |
970d7e83 | 449 | } |
476ff2be | 450 | |
add651ee FG |
451 | pub fn truncate_to(&self, tcx: TyCtxt<'tcx>, generics: &ty::Generics) -> GenericArgsRef<'tcx> { |
452 | tcx.mk_args_from_iter(self.iter().take(generics.count())) | |
476ff2be | 453 | } |
fe692bf9 FG |
454 | |
455 | pub fn host_effect_param(&'tcx self) -> Option<ty::Const<'tcx>> { | |
456 | self.consts().rfind(|x| matches!(x.kind(), ty::ConstKind::Param(p) if p.name == sym::host)) | |
457 | } | |
781aab86 FG |
458 | |
459 | pub fn print_as_list(&self) -> String { | |
460 | let v = self.iter().map(|arg| arg.to_string()).collect::<Vec<_>>(); | |
461 | format!("[{}]", v.join(", ")) | |
462 | } | |
970d7e83 LB |
463 | } |
464 | ||
add651ee | 465 | impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for GenericArgsRef<'tcx> { |
9ffffee4 FG |
466 | fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>( |
467 | self, | |
468 | folder: &mut F, | |
469 | ) -> Result<Self, F::Error> { | |
e74abb32 XL |
470 | // This code is hot enough that it's worth specializing for the most |
471 | // common length lists, to avoid the overhead of `SmallVec` creation. | |
472 | // The match arms are in order of frequency. The 1, 2, and 0 cases are | |
473 | // typically hit in 90--99.99% of cases. When folding doesn't change | |
add651ee FG |
474 | // the args, it's faster to reuse the existing args rather than |
475 | // calling `mk_args`. | |
e74abb32 XL |
476 | match self.len() { |
477 | 1 => { | |
a2a8927a | 478 | let param0 = self[0].try_fold_with(folder)?; |
add651ee | 479 | if param0 == self[0] { Ok(self) } else { Ok(folder.interner().mk_args(&[param0])) } |
e74abb32 XL |
480 | } |
481 | 2 => { | |
a2a8927a XL |
482 | let param0 = self[0].try_fold_with(folder)?; |
483 | let param1 = self[1].try_fold_with(folder)?; | |
e74abb32 | 484 | if param0 == self[0] && param1 == self[1] { |
a2a8927a | 485 | Ok(self) |
e74abb32 | 486 | } else { |
add651ee | 487 | Ok(folder.interner().mk_args(&[param0, param1])) |
e74abb32 XL |
488 | } |
489 | } | |
a2a8927a | 490 | 0 => Ok(self), |
add651ee | 491 | _ => ty::util::fold_list(self, folder, |tcx, v| tcx.mk_args(v)), |
c30ab7b3 | 492 | } |
7453a54e | 493 | } |
064997fb | 494 | } |
85aaf69f | 495 | |
9ffffee4 FG |
496 | impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<Ty<'tcx>> { |
497 | fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>( | |
498 | self, | |
499 | folder: &mut F, | |
500 | ) -> Result<Self, F::Error> { | |
add651ee | 501 | // This code is fairly hot, though not as hot as `GenericArgsRef`. |
5e7ed085 FG |
502 | // |
503 | // When compiling stage 2, I get the following results: | |
504 | // | |
505 | // len | total | % | |
506 | // --- | --------- | ----- | |
507 | // 2 | 15083590 | 48.1 | |
508 | // 3 | 7540067 | 24.0 | |
509 | // 1 | 5300377 | 16.9 | |
510 | // 4 | 1351897 | 4.3 | |
511 | // 0 | 1256849 | 4.0 | |
512 | // | |
513 | // I've tried it with some private repositories and got | |
514 | // close to the same result, with 4 and 0 swapping places | |
515 | // sometimes. | |
516 | match self.len() { | |
517 | 2 => { | |
518 | let param0 = self[0].try_fold_with(folder)?; | |
519 | let param1 = self[1].try_fold_with(folder)?; | |
520 | if param0 == self[0] && param1 == self[1] { | |
521 | Ok(self) | |
522 | } else { | |
9ffffee4 | 523 | Ok(folder.interner().mk_type_list(&[param0, param1])) |
5e7ed085 FG |
524 | } |
525 | } | |
9ffffee4 | 526 | _ => ty::util::fold_list(self, folder, |tcx, v| tcx.mk_type_list(v)), |
5e7ed085 FG |
527 | } |
528 | } | |
064997fb | 529 | } |
5e7ed085 | 530 | |
9ffffee4 | 531 | impl<'tcx, T: TypeVisitable<TyCtxt<'tcx>>> TypeVisitable<TyCtxt<'tcx>> for &'tcx ty::List<T> { |
2b03887a | 532 | #[inline] |
9ffffee4 | 533 | fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> { |
5e7ed085 FG |
534 | self.iter().try_for_each(|t| t.visit_with(visitor)) |
535 | } | |
536 | } | |
537 | ||
487cf647 | 538 | /// Similar to [`super::Binder`] except that it tracks early bound generics, i.e. `struct Foo<T>(T)` |
add651ee FG |
539 | /// needs `T` instantiated immediately. This type primarily exists to avoid forgetting to call |
540 | /// `instantiate`. | |
9c376795 | 541 | /// |
add651ee FG |
542 | /// If you don't have anything to `instantiate`, you may be looking for |
543 | /// [`instantiate_identity`](EarlyBinder::instantiate_identity) or [`skip_binder`](EarlyBinder::skip_binder). | |
2b03887a FG |
544 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)] |
545 | #[derive(Encodable, Decodable, HashStable)] | |
fe692bf9 FG |
546 | pub struct EarlyBinder<T> { |
547 | value: T, | |
548 | } | |
2b03887a | 549 | |
add651ee | 550 | /// For early binders, you should first call `instantiate` before using any visitors. |
9ffffee4 FG |
551 | impl<'tcx, T> !TypeFoldable<TyCtxt<'tcx>> for ty::EarlyBinder<T> {} |
552 | impl<'tcx, T> !TypeVisitable<TyCtxt<'tcx>> for ty::EarlyBinder<T> {} | |
2b03887a FG |
553 | |
554 | impl<T> EarlyBinder<T> { | |
fe692bf9 FG |
555 | pub fn bind(value: T) -> EarlyBinder<T> { |
556 | EarlyBinder { value } | |
557 | } | |
558 | ||
2b03887a | 559 | pub fn as_ref(&self) -> EarlyBinder<&T> { |
fe692bf9 | 560 | EarlyBinder { value: &self.value } |
2b03887a | 561 | } |
1a4d82fc | 562 | |
2b03887a FG |
563 | pub fn map_bound_ref<F, U>(&self, f: F) -> EarlyBinder<U> |
564 | where | |
565 | F: FnOnce(&T) -> U, | |
566 | { | |
567 | self.as_ref().map_bound(f) | |
568 | } | |
569 | ||
570 | pub fn map_bound<F, U>(self, f: F) -> EarlyBinder<U> | |
571 | where | |
572 | F: FnOnce(T) -> U, | |
573 | { | |
fe692bf9 FG |
574 | let value = f(self.value); |
575 | EarlyBinder { value } | |
2b03887a FG |
576 | } |
577 | ||
578 | pub fn try_map_bound<F, U, E>(self, f: F) -> Result<EarlyBinder<U>, E> | |
579 | where | |
580 | F: FnOnce(T) -> Result<U, E>, | |
581 | { | |
fe692bf9 FG |
582 | let value = f(self.value)?; |
583 | Ok(EarlyBinder { value }) | |
2b03887a FG |
584 | } |
585 | ||
586 | pub fn rebind<U>(&self, value: U) -> EarlyBinder<U> { | |
fe692bf9 | 587 | EarlyBinder { value } |
2b03887a | 588 | } |
9c376795 FG |
589 | |
590 | /// Skips the binder and returns the "bound" value. | |
591 | /// This can be used to extract data that does not depend on generic parameters | |
592 | /// (e.g., getting the `DefId` of the inner value or getting the number of | |
593 | /// arguments of an `FnSig`). Otherwise, consider using | |
add651ee | 594 | /// [`instantiate_identity`](EarlyBinder::instantiate_identity). |
9c376795 | 595 | /// |
fe692bf9 FG |
596 | /// To skip the binder on `x: &EarlyBinder<T>` to obtain `&T`, leverage |
597 | /// [`EarlyBinder::as_ref`](EarlyBinder::as_ref): `x.as_ref().skip_binder()`. | |
598 | /// | |
9c376795 FG |
599 | /// See also [`Binder::skip_binder`](super::Binder::skip_binder), which is |
600 | /// the analogous operation on [`super::Binder`]. | |
601 | pub fn skip_binder(self) -> T { | |
fe692bf9 | 602 | self.value |
9c376795 | 603 | } |
1a4d82fc JJ |
604 | } |
605 | ||
2b03887a FG |
606 | impl<T> EarlyBinder<Option<T>> { |
607 | pub fn transpose(self) -> Option<EarlyBinder<T>> { | |
fe692bf9 | 608 | self.value.map(|value| EarlyBinder { value }) |
2b03887a FG |
609 | } |
610 | } | |
611 | ||
612 | impl<T, U> EarlyBinder<(T, U)> { | |
613 | pub fn transpose_tuple2(self) -> (EarlyBinder<T>, EarlyBinder<U>) { | |
fe692bf9 FG |
614 | let EarlyBinder { value: (lhs, rhs) } = self; |
615 | (EarlyBinder { value: lhs }, EarlyBinder { value: rhs }) | |
2b03887a FG |
616 | } |
617 | } | |
04454e1e | 618 | |
487cf647 FG |
619 | impl<'tcx, 's, I: IntoIterator> EarlyBinder<I> |
620 | where | |
9ffffee4 | 621 | I::Item: TypeFoldable<TyCtxt<'tcx>>, |
487cf647 | 622 | { |
add651ee | 623 | pub fn iter_instantiated( |
2b03887a FG |
624 | self, |
625 | tcx: TyCtxt<'tcx>, | |
add651ee FG |
626 | args: &'s [GenericArg<'tcx>], |
627 | ) -> IterInstantiated<'s, 'tcx, I> { | |
628 | IterInstantiated { it: self.value.into_iter(), tcx, args } | |
487cf647 | 629 | } |
49aad941 | 630 | |
add651ee | 631 | /// Similar to [`instantiate_identity`](EarlyBinder::instantiate_identity), |
49aad941 | 632 | /// but on an iterator of `TypeFoldable` values. |
add651ee | 633 | pub fn instantiate_identity_iter(self) -> I::IntoIter { |
fe692bf9 | 634 | self.value.into_iter() |
49aad941 | 635 | } |
487cf647 FG |
636 | } |
637 | ||
add651ee | 638 | pub struct IterInstantiated<'s, 'tcx, I: IntoIterator> { |
487cf647 FG |
639 | it: I::IntoIter, |
640 | tcx: TyCtxt<'tcx>, | |
add651ee | 641 | args: &'s [GenericArg<'tcx>], |
487cf647 FG |
642 | } |
643 | ||
add651ee | 644 | impl<'tcx, I: IntoIterator> Iterator for IterInstantiated<'_, 'tcx, I> |
487cf647 | 645 | where |
9ffffee4 | 646 | I::Item: TypeFoldable<TyCtxt<'tcx>>, |
487cf647 FG |
647 | { |
648 | type Item = I::Item; | |
649 | ||
650 | fn next(&mut self) -> Option<Self::Item> { | |
add651ee | 651 | Some(EarlyBinder { value: self.it.next()? }.instantiate(self.tcx, self.args)) |
487cf647 FG |
652 | } |
653 | ||
654 | fn size_hint(&self) -> (usize, Option<usize>) { | |
655 | self.it.size_hint() | |
2b03887a FG |
656 | } |
657 | } | |
658 | ||
add651ee | 659 | impl<'tcx, I: IntoIterator> DoubleEndedIterator for IterInstantiated<'_, 'tcx, I> |
487cf647 FG |
660 | where |
661 | I::IntoIter: DoubleEndedIterator, | |
9ffffee4 | 662 | I::Item: TypeFoldable<TyCtxt<'tcx>>, |
487cf647 FG |
663 | { |
664 | fn next_back(&mut self) -> Option<Self::Item> { | |
add651ee | 665 | Some(EarlyBinder { value: self.it.next_back()? }.instantiate(self.tcx, self.args)) |
487cf647 FG |
666 | } |
667 | } | |
668 | ||
add651ee | 669 | impl<'tcx, I: IntoIterator> ExactSizeIterator for IterInstantiated<'_, 'tcx, I> |
9c376795 FG |
670 | where |
671 | I::IntoIter: ExactSizeIterator, | |
9ffffee4 | 672 | I::Item: TypeFoldable<TyCtxt<'tcx>>, |
9c376795 FG |
673 | { |
674 | } | |
675 | ||
487cf647 FG |
676 | impl<'tcx, 's, I: IntoIterator> EarlyBinder<I> |
677 | where | |
678 | I::Item: Deref, | |
9ffffee4 | 679 | <I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>, |
2b03887a | 680 | { |
add651ee | 681 | pub fn iter_instantiated_copied( |
2b03887a FG |
682 | self, |
683 | tcx: TyCtxt<'tcx>, | |
add651ee FG |
684 | args: &'s [GenericArg<'tcx>], |
685 | ) -> IterInstantiatedCopied<'s, 'tcx, I> { | |
686 | IterInstantiatedCopied { it: self.value.into_iter(), tcx, args } | |
487cf647 | 687 | } |
49aad941 | 688 | |
add651ee | 689 | /// Similar to [`instantiate_identity`](EarlyBinder::instantiate_identity), |
49aad941 | 690 | /// but on an iterator of values that deref to a `TypeFoldable`. |
add651ee FG |
691 | pub fn instantiate_identity_iter_copied( |
692 | self, | |
693 | ) -> impl Iterator<Item = <I::Item as Deref>::Target> { | |
fe692bf9 | 694 | self.value.into_iter().map(|v| *v) |
49aad941 | 695 | } |
487cf647 FG |
696 | } |
697 | ||
add651ee | 698 | pub struct IterInstantiatedCopied<'a, 'tcx, I: IntoIterator> { |
487cf647 FG |
699 | it: I::IntoIter, |
700 | tcx: TyCtxt<'tcx>, | |
add651ee | 701 | args: &'a [GenericArg<'tcx>], |
487cf647 FG |
702 | } |
703 | ||
add651ee | 704 | impl<'tcx, I: IntoIterator> Iterator for IterInstantiatedCopied<'_, 'tcx, I> |
487cf647 FG |
705 | where |
706 | I::Item: Deref, | |
9ffffee4 | 707 | <I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>, |
487cf647 FG |
708 | { |
709 | type Item = <I::Item as Deref>::Target; | |
710 | ||
711 | fn next(&mut self) -> Option<Self::Item> { | |
add651ee | 712 | self.it.next().map(|value| EarlyBinder { value: *value }.instantiate(self.tcx, self.args)) |
487cf647 FG |
713 | } |
714 | ||
715 | fn size_hint(&self) -> (usize, Option<usize>) { | |
716 | self.it.size_hint() | |
717 | } | |
718 | } | |
719 | ||
add651ee | 720 | impl<'tcx, I: IntoIterator> DoubleEndedIterator for IterInstantiatedCopied<'_, 'tcx, I> |
487cf647 FG |
721 | where |
722 | I::IntoIter: DoubleEndedIterator, | |
723 | I::Item: Deref, | |
9ffffee4 | 724 | <I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>, |
487cf647 FG |
725 | { |
726 | fn next_back(&mut self) -> Option<Self::Item> { | |
add651ee FG |
727 | self.it |
728 | .next_back() | |
729 | .map(|value| EarlyBinder { value: *value }.instantiate(self.tcx, self.args)) | |
2b03887a FG |
730 | } |
731 | } | |
732 | ||
add651ee | 733 | impl<'tcx, I: IntoIterator> ExactSizeIterator for IterInstantiatedCopied<'_, 'tcx, I> |
9c376795 FG |
734 | where |
735 | I::IntoIter: ExactSizeIterator, | |
736 | I::Item: Deref, | |
9ffffee4 | 737 | <I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>, |
9c376795 FG |
738 | { |
739 | } | |
740 | ||
2b03887a FG |
741 | pub struct EarlyBinderIter<T> { |
742 | t: T, | |
743 | } | |
744 | ||
745 | impl<T: IntoIterator> EarlyBinder<T> { | |
746 | pub fn transpose_iter(self) -> EarlyBinderIter<T::IntoIter> { | |
fe692bf9 | 747 | EarlyBinderIter { t: self.value.into_iter() } |
2b03887a FG |
748 | } |
749 | } | |
750 | ||
751 | impl<T: Iterator> Iterator for EarlyBinderIter<T> { | |
752 | type Item = EarlyBinder<T::Item>; | |
753 | ||
754 | fn next(&mut self) -> Option<Self::Item> { | |
fe692bf9 | 755 | self.t.next().map(|value| EarlyBinder { value }) |
2b03887a | 756 | } |
487cf647 FG |
757 | |
758 | fn size_hint(&self) -> (usize, Option<usize>) { | |
759 | self.t.size_hint() | |
760 | } | |
2b03887a FG |
761 | } |
762 | ||
9ffffee4 | 763 | impl<'tcx, T: TypeFoldable<TyCtxt<'tcx>>> ty::EarlyBinder<T> { |
add651ee FG |
764 | pub fn instantiate(self, tcx: TyCtxt<'tcx>, args: &[GenericArg<'tcx>]) -> T { |
765 | let mut folder = ArgFolder { tcx, args, binders_passed: 0 }; | |
fe692bf9 | 766 | self.value.fold_with(&mut folder) |
1a4d82fc | 767 | } |
9c376795 | 768 | |
add651ee | 769 | /// Makes the identity replacement `T0 => T0, ..., TN => TN`. |
9c376795 FG |
770 | /// Conceptually, this converts universally bound variables into placeholders |
771 | /// when inside of a given item. | |
772 | /// | |
773 | /// For example, consider `for<T> fn foo<T>(){ .. }`: | |
774 | /// - Outside of `foo`, `T` is bound (represented by the presence of `EarlyBinder`). | |
775 | /// - Inside of the body of `foo`, we treat `T` as a placeholder by calling | |
add651ee FG |
776 | /// `instantiate_identity` to discharge the `EarlyBinder`. |
777 | pub fn instantiate_identity(self) -> T { | |
fe692bf9 | 778 | self.value |
9c376795 | 779 | } |
9ffffee4 FG |
780 | |
781 | /// Returns the inner value, but only if it contains no bound vars. | |
782 | pub fn no_bound_vars(self) -> Option<T> { | |
fe692bf9 | 783 | if !self.value.has_param() { Some(self.value) } else { None } |
9ffffee4 | 784 | } |
1a4d82fc JJ |
785 | } |
786 | ||
787 | /////////////////////////////////////////////////////////////////////////// | |
788 | // The actual substitution engine itself is a type folder. | |
789 | ||
add651ee | 790 | struct ArgFolder<'a, 'tcx> { |
dc9dc135 | 791 | tcx: TyCtxt<'tcx>, |
add651ee | 792 | args: &'a [GenericArg<'tcx>], |
1a4d82fc | 793 | |
48663c56 | 794 | /// Number of region binders we have passed through while doing the substitution |
a1dfa0c6 | 795 | binders_passed: u32, |
1a4d82fc JJ |
796 | } |
797 | ||
add651ee | 798 | impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for ArgFolder<'a, 'tcx> { |
064997fb | 799 | #[inline] |
9ffffee4 | 800 | fn interner(&self) -> TyCtxt<'tcx> { |
dfeec247 XL |
801 | self.tcx |
802 | } | |
1a4d82fc | 803 | |
9ffffee4 | 804 | fn fold_binder<T: TypeFoldable<TyCtxt<'tcx>>>( |
cdc7bbd5 XL |
805 | &mut self, |
806 | t: ty::Binder<'tcx, T>, | |
807 | ) -> ty::Binder<'tcx, T> { | |
a1dfa0c6 | 808 | self.binders_passed += 1; |
54a0048b | 809 | let t = t.super_fold_with(self); |
a1dfa0c6 | 810 | self.binders_passed -= 1; |
54a0048b | 811 | t |
1a4d82fc JJ |
812 | } |
813 | ||
7cac9316 | 814 | fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { |
064997fb FG |
815 | #[cold] |
816 | #[inline(never)] | |
add651ee | 817 | fn region_param_out_of_range(data: ty::EarlyBoundRegion, args: &[GenericArg<'_>]) -> ! { |
064997fb | 818 | bug!( |
add651ee | 819 | "Region parameter out of range when substituting in region {} (index={}, args = {:?})", |
2b03887a FG |
820 | data.name, |
821 | data.index, | |
add651ee | 822 | args, |
2b03887a FG |
823 | ) |
824 | } | |
825 | ||
826 | #[cold] | |
827 | #[inline(never)] | |
828 | fn region_param_invalid(data: ty::EarlyBoundRegion, other: GenericArgKind<'_>) -> ! { | |
829 | bug!( | |
830 | "Unexpected parameter {:?} when substituting in region {} (index={})", | |
831 | other, | |
064997fb FG |
832 | data.name, |
833 | data.index | |
834 | ) | |
835 | } | |
836 | ||
1a4d82fc JJ |
837 | // Note: This routine only handles regions that are bound on |
838 | // type declarations and other outer declarations, not those | |
839 | // bound in *fn types*. Region substitution of the bound | |
840 | // regions that appear in a function signature is done using | |
841 | // the specialized routine `ty::replace_late_regions()`. | |
9e0c209e | 842 | match *r { |
9346a6ac | 843 | ty::ReEarlyBound(data) => { |
add651ee | 844 | let rk = self.args.get(data.index as usize).map(|k| k.unpack()); |
48663c56 | 845 | match rk { |
dfeec247 | 846 | Some(GenericArgKind::Lifetime(lt)) => self.shift_region_through_binders(lt), |
2b03887a | 847 | Some(other) => region_param_invalid(data, other), |
add651ee | 848 | None => region_param_out_of_range(data, self.args), |
970d7e83 LB |
849 | } |
850 | } | |
49aad941 FG |
851 | ty::ReLateBound(..) |
852 | | ty::ReFree(_) | |
853 | | ty::ReStatic | |
854 | | ty::RePlaceholder(_) | |
855 | | ty::ReErased | |
856 | | ty::ReError(_) => r, | |
857 | ty::ReVar(_) => bug!("unexpected region: {r:?}"), | |
970d7e83 LB |
858 | } |
859 | } | |
1a4d82fc JJ |
860 | |
861 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
49aad941 | 862 | if !t.has_param() { |
1a4d82fc JJ |
863 | return t; |
864 | } | |
865 | ||
1b1a35ee | 866 | match *t.kind() { |
dfeec247 XL |
867 | ty::Param(p) => self.ty_for_param(p, t), |
868 | _ => t.super_fold_with(self), | |
1a4d82fc | 869 | } |
1a4d82fc | 870 | } |
532ac7d7 | 871 | |
5099ac24 | 872 | fn fold_const(&mut self, c: ty::Const<'tcx>) -> ty::Const<'tcx> { |
923072b8 | 873 | if let ty::ConstKind::Param(p) = c.kind() { |
532ac7d7 XL |
874 | self.const_for_param(p, c) |
875 | } else { | |
876 | c.super_fold_with(self) | |
877 | } | |
878 | } | |
970d7e83 LB |
879 | } |
880 | ||
add651ee | 881 | impl<'a, 'tcx> ArgFolder<'a, 'tcx> { |
1a4d82fc | 882 | fn ty_for_param(&self, p: ty::ParamTy, source_ty: Ty<'tcx>) -> Ty<'tcx> { |
add651ee FG |
883 | // Look up the type in the args. It really should be in there. |
884 | let opt_ty = self.args.get(p.index as usize).map(|k| k.unpack()); | |
1a4d82fc | 885 | let ty = match opt_ty { |
e74abb32 | 886 | Some(GenericArgKind::Type(ty)) => ty, |
064997fb FG |
887 | Some(kind) => self.type_param_expected(p, source_ty, kind), |
888 | None => self.type_param_out_of_range(p, source_ty), | |
1a4d82fc JJ |
889 | }; |
890 | ||
a1dfa0c6 | 891 | self.shift_vars_through_binders(ty) |
1a4d82fc JJ |
892 | } |
893 | ||
064997fb FG |
894 | #[cold] |
895 | #[inline(never)] | |
896 | fn type_param_expected(&self, p: ty::ParamTy, ty: Ty<'tcx>, kind: GenericArgKind<'tcx>) -> ! { | |
897 | bug!( | |
add651ee | 898 | "expected type for `{:?}` ({:?}/{}) but found {:?} when substituting, args={:?}", |
064997fb FG |
899 | p, |
900 | ty, | |
901 | p.index, | |
902 | kind, | |
add651ee | 903 | self.args, |
064997fb FG |
904 | ) |
905 | } | |
906 | ||
907 | #[cold] | |
908 | #[inline(never)] | |
909 | fn type_param_out_of_range(&self, p: ty::ParamTy, ty: Ty<'tcx>) -> ! { | |
910 | bug!( | |
add651ee | 911 | "type parameter `{:?}` ({:?}/{}) out of range when substituting, args={:?}", |
064997fb FG |
912 | p, |
913 | ty, | |
914 | p.index, | |
add651ee | 915 | self.args, |
064997fb FG |
916 | ) |
917 | } | |
918 | ||
5099ac24 | 919 | fn const_for_param(&self, p: ParamConst, source_ct: ty::Const<'tcx>) -> ty::Const<'tcx> { |
add651ee FG |
920 | // Look up the const in the args. It really should be in there. |
921 | let opt_ct = self.args.get(p.index as usize).map(|k| k.unpack()); | |
48663c56 | 922 | let ct = match opt_ct { |
e74abb32 | 923 | Some(GenericArgKind::Const(ct)) => ct, |
064997fb FG |
924 | Some(kind) => self.const_param_expected(p, source_ct, kind), |
925 | None => self.const_param_out_of_range(p, source_ct), | |
532ac7d7 XL |
926 | }; |
927 | ||
48663c56 | 928 | self.shift_vars_through_binders(ct) |
532ac7d7 XL |
929 | } |
930 | ||
064997fb FG |
931 | #[cold] |
932 | #[inline(never)] | |
933 | fn const_param_expected( | |
934 | &self, | |
935 | p: ty::ParamConst, | |
936 | ct: ty::Const<'tcx>, | |
937 | kind: GenericArgKind<'tcx>, | |
938 | ) -> ! { | |
939 | bug!( | |
add651ee | 940 | "expected const for `{:?}` ({:?}/{}) but found {:?} when substituting args={:?}", |
064997fb FG |
941 | p, |
942 | ct, | |
943 | p.index, | |
944 | kind, | |
add651ee | 945 | self.args, |
064997fb FG |
946 | ) |
947 | } | |
948 | ||
949 | #[cold] | |
950 | #[inline(never)] | |
951 | fn const_param_out_of_range(&self, p: ty::ParamConst, ct: ty::Const<'tcx>) -> ! { | |
952 | bug!( | |
add651ee | 953 | "const parameter `{:?}` ({:?}/{}) out of range when substituting args={:?}", |
064997fb FG |
954 | p, |
955 | ct, | |
956 | p.index, | |
add651ee | 957 | self.args, |
064997fb FG |
958 | ) |
959 | } | |
960 | ||
9fa01778 | 961 | /// It is sometimes necessary to adjust the De Bruijn indices during substitution. This occurs |
a1dfa0c6 XL |
962 | /// when we are substituting a type with escaping bound vars into a context where we have |
963 | /// passed through binders. That's quite a mouthful. Let's see an example: | |
1a4d82fc JJ |
964 | /// |
965 | /// ``` | |
966 | /// type Func<A> = fn(A); | |
04454e1e | 967 | /// type MetaFunc = for<'a> fn(Func<&'a i32>); |
1a4d82fc JJ |
968 | /// ``` |
969 | /// | |
970 | /// The type `MetaFunc`, when fully expanded, will be | |
04454e1e FG |
971 | /// ```ignore (illustrative) |
972 | /// for<'a> fn(fn(&'a i32)) | |
973 | /// // ^~ ^~ ^~~ | |
974 | /// // | | | | |
975 | /// // | | DebruijnIndex of 2 | |
976 | /// // Binders | |
977 | /// ``` | |
1a4d82fc JJ |
978 | /// Here the `'a` lifetime is bound in the outer function, but appears as an argument of the |
979 | /// inner one. Therefore, that appearance will have a DebruijnIndex of 2, because we must skip | |
9fa01778 | 980 | /// over the inner binder (remember that we count De Bruijn indices from 1). However, in the |
f035d41b | 981 | /// definition of `MetaFunc`, the binder is not visible, so the type `&'a i32` will have a |
9fa01778 | 982 | /// De Bruijn index of 1. It's only during the substitution that we can see we must increase the |
1a4d82fc JJ |
983 | /// depth by 1 to account for the binder that we passed through. |
984 | /// | |
985 | /// As a second example, consider this twist: | |
986 | /// | |
987 | /// ``` | |
988 | /// type FuncTuple<A> = (A,fn(A)); | |
04454e1e | 989 | /// type MetaFuncTuple = for<'a> fn(FuncTuple<&'a i32>); |
1a4d82fc JJ |
990 | /// ``` |
991 | /// | |
992 | /// Here the final type will be: | |
04454e1e FG |
993 | /// ```ignore (illustrative) |
994 | /// for<'a> fn((&'a i32, fn(&'a i32))) | |
995 | /// // ^~~ ^~~ | |
996 | /// // | | | |
997 | /// // DebruijnIndex of 1 | | |
998 | /// // DebruijnIndex of 2 | |
999 | /// ``` | |
f035d41b | 1000 | /// As indicated in the diagram, here the same type `&'a i32` is substituted once, but in the |
9fa01778 | 1001 | /// first case we do not increase the De Bruijn index and in the second case we do. The reason |
1a4d82fc | 1002 | /// is that only in the second case have we passed through a fn binder. |
9ffffee4 | 1003 | fn shift_vars_through_binders<T: TypeFoldable<TyCtxt<'tcx>>>(&self, val: T) -> T { |
dfeec247 XL |
1004 | debug!( |
1005 | "shift_vars(val={:?}, binders_passed={:?}, has_escaping_bound_vars={:?})", | |
1006 | val, | |
1007 | self.binders_passed, | |
1008 | val.has_escaping_bound_vars() | |
1009 | ); | |
1a4d82fc | 1010 | |
48663c56 XL |
1011 | if self.binders_passed == 0 || !val.has_escaping_bound_vars() { |
1012 | return val; | |
970d7e83 | 1013 | } |
1a4d82fc | 1014 | |
9ffffee4 | 1015 | let result = ty::fold::shift_vars(TypeFolder::interner(self), val, self.binders_passed); |
a1dfa0c6 | 1016 | debug!("shift_vars: shifted result = {:?}", result); |
1a4d82fc JJ |
1017 | |
1018 | result | |
1019 | } | |
1020 | ||
7cac9316 | 1021 | fn shift_region_through_binders(&self, region: ty::Region<'tcx>) -> ty::Region<'tcx> { |
a1dfa0c6 | 1022 | if self.binders_passed == 0 || !region.has_escaping_bound_vars() { |
cc61c64b XL |
1023 | return region; |
1024 | } | |
a1dfa0c6 | 1025 | ty::fold::shift_region(self.tcx, region, self.binders_passed) |
9e0c209e SL |
1026 | } |
1027 | } | |
0bf4aa26 | 1028 | |
add651ee | 1029 | /// Stores the user-given args to reach some fully qualified path |
0bf4aa26 | 1030 | /// (e.g., `<T>::Item` or `<T as Trait>::Item`). |
3dfed10e | 1031 | #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] |
781aab86 | 1032 | #[derive(HashStable, TypeFoldable, TypeVisitable)] |
add651ee FG |
1033 | pub struct UserArgs<'tcx> { |
1034 | /// The args for the item as given by the user. | |
1035 | pub args: GenericArgsRef<'tcx>, | |
0bf4aa26 | 1036 | |
9fa01778 | 1037 | /// The self type, in the case of a `<T>::Item` path (when applied |
0bf4aa26 XL |
1038 | /// to an inherent impl). See `UserSelfTy` below. |
1039 | pub user_self_ty: Option<UserSelfTy<'tcx>>, | |
1040 | } | |
1041 | ||
9fa01778 XL |
1042 | /// Specifies the user-given self type. In the case of a path that |
1043 | /// refers to a member in an inherent impl, this self type is | |
0bf4aa26 XL |
1044 | /// sometimes needed to constrain the type parameters on the impl. For |
1045 | /// example, in this code: | |
1046 | /// | |
04454e1e | 1047 | /// ```ignore (illustrative) |
0bf4aa26 XL |
1048 | /// struct Foo<T> { } |
1049 | /// impl<A> Foo<A> { fn method() { } } | |
1050 | /// ``` | |
1051 | /// | |
1052 | /// when you then have a path like `<Foo<&'static u32>>::method`, | |
9fa01778 XL |
1053 | /// this struct would carry the `DefId` of the impl along with the |
1054 | /// self type `Foo<u32>`. Then we can instantiate the parameters of | |
add651ee | 1055 | /// the impl (with the args from `UserArgs`) and apply those to |
9fa01778 XL |
1056 | /// the self type, giving `Foo<?A>`. Finally, we unify that with |
1057 | /// the self type here, which contains `?A` to be `&'static u32` | |
3dfed10e | 1058 | #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] |
781aab86 | 1059 | #[derive(HashStable, TypeFoldable, TypeVisitable)] |
0bf4aa26 XL |
1060 | pub struct UserSelfTy<'tcx> { |
1061 | pub impl_def_id: DefId, | |
1062 | pub self_ty: Ty<'tcx>, | |
1063 | } |