1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480
#![allow(rustc::usage_of_ty_tykind)]
use std::cmp::Ordering;
use std::{fmt, hash};
use crate::FloatTy;
use crate::HashStableContext;
use crate::IntTy;
use crate::Interner;
use crate::TyDecoder;
use crate::TyEncoder;
use crate::UintTy;
use crate::{DebruijnIndex, DebugWithInfcx, InferCtxtLike, OptWithInfcx};
use self::RegionKind::*;
use self::TyKind::*;
use rustc_data_structures::stable_hasher::HashStable;
use rustc_serialize::{Decodable, Decoder, Encodable};
/// Specifies how a trait object is represented.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
#[derive(Encodable, Decodable, HashStable_Generic)]
pub enum DynKind {
/// An unsized `dyn Trait` object
Dyn,
/// A sized `dyn* Trait` object
///
/// These objects are represented as a `(data, vtable)` pair where `data` is a value of some
/// ptr-sized and ptr-aligned dynamically determined type `T` and `vtable` is a pointer to the
/// vtable of `impl T for Trait`. This allows a `dyn*` object to be treated agnostically with
/// respect to whether it points to a `Box<T>`, `Rc<T>`, etc.
DynStar,
}
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
#[derive(Encodable, Decodable, HashStable_Generic)]
pub enum AliasKind {
/// A projection `<Type as Trait>::AssocType`.
/// Can get normalized away if monomorphic enough.
Projection,
/// An associated type in an inherent `impl`
Inherent,
/// An opaque type (usually from `impl Trait` in type aliases or function return types)
/// Can only be normalized away in RevealAll mode
Opaque,
/// A type alias that actually checks its trait bounds.
/// Currently only used if the type alias references opaque types.
/// Can always be normalized away.
Weak,
}
/// Defines the kinds of types used by the type system.
///
/// Types written by the user start out as `hir::TyKind` and get
/// converted to this representation using `AstConv::ast_ty_to_ty`.
#[rustc_diagnostic_item = "IrTyKind"]
pub enum TyKind<I: Interner> {
/// The primitive boolean type. Written as `bool`.
Bool,
/// The primitive character type; holds a Unicode scalar value
/// (a non-surrogate code point). Written as `char`.
Char,
/// A primitive signed integer type. For example, `i32`.
Int(IntTy),
/// A primitive unsigned integer type. For example, `u32`.
Uint(UintTy),
/// A primitive floating-point type. For example, `f64`.
Float(FloatTy),
/// Algebraic data types (ADT). For example: structures, enumerations and unions.
///
/// For example, the type `List<i32>` would be represented using the `AdtDef`
/// for `struct List<T>` and the args `[i32]`.
///
/// Note that generic parameters in fields only get lazily substituted
/// by using something like `adt_def.all_fields().map(|field| field.ty(tcx, args))`.
Adt(I::AdtDef, I::GenericArgsRef),
/// An unsized FFI type that is opaque to Rust. Written as `extern type T`.
Foreign(I::DefId),
/// The pointee of a string slice. Written as `str`.
Str,
/// An array with the given length. Written as `[T; N]`.
Array(I::Ty, I::Const),
/// The pointee of an array slice. Written as `[T]`.
Slice(I::Ty),
/// A raw pointer. Written as `*mut T` or `*const T`
RawPtr(I::TypeAndMut),
/// A reference; a pointer with an associated lifetime. Written as
/// `&'a mut T` or `&'a T`.
Ref(I::Region, I::Ty, I::Mutability),
/// The anonymous type of a function declaration/definition. Each
/// function has a unique type.
///
/// For the function `fn foo() -> i32 { 3 }` this type would be
/// shown to the user as `fn() -> i32 {foo}`.
///
/// For example the type of `bar` here:
/// ```rust
/// fn foo() -> i32 { 1 }
/// let bar = foo; // bar: fn() -> i32 {foo}
/// ```
FnDef(I::DefId, I::GenericArgsRef),
/// A pointer to a function. Written as `fn() -> i32`.
///
/// Note that both functions and closures start out as either
/// [FnDef] or [Closure] which can be then be coerced to this variant.
///
/// For example the type of `bar` here:
///
/// ```rust
/// fn foo() -> i32 { 1 }
/// let bar: fn() -> i32 = foo;
/// ```
FnPtr(I::PolyFnSig),
/// A trait object. Written as `dyn for<'b> Trait<'b, Assoc = u32> + Send + 'a`.
Dynamic(I::ListBinderExistentialPredicate, I::Region, DynKind),
/// The anonymous type of a closure. Used to represent the type of `|a| a`.
///
/// Closure args contain both the - potentially substituted - generic parameters
/// of its parent and some synthetic parameters. See the documentation for
/// `ClosureArgs` for more details.
Closure(I::DefId, I::GenericArgsRef),
/// The anonymous type of a generator. Used to represent the type of
/// `|a| yield a`.
///
/// For more info about generator args, visit the documentation for
/// `GeneratorArgs`.
Generator(I::DefId, I::GenericArgsRef, I::Movability),
/// A type representing the types stored inside a generator.
/// This should only appear as part of the `GeneratorArgs`.
///
/// Unlike upvars, the witness can reference lifetimes from
/// inside of the generator itself. To deal with them in
/// the type of the generator, we convert them to higher ranked
/// lifetimes bound by the witness itself.
///
/// This variant is only using when `drop_tracking_mir` is set.
/// This contains the `DefId` and the `GenericArgsRef` of the generator.
/// The actual witness types are computed on MIR by the `mir_generator_witnesses` query.
///
/// Looking at the following example, the witness for this generator
/// may end up as something like `for<'a> [Vec<i32>, &'a Vec<i32>]`:
///
/// ```ignore UNSOLVED (ask @compiler-errors, should this error? can we just swap the yields?)
/// #![feature(generators)]
/// |a| {
/// let x = &vec![3];
/// yield a;
/// yield x[0];
/// }
/// # ;
/// ```
GeneratorWitness(I::DefId, I::GenericArgsRef),
/// The never type `!`.
Never,
/// A tuple type. For example, `(i32, bool)`.
Tuple(I::ListTy),
/// A projection, opaque type, weak type alias, or inherent associated type.
/// All of these types are represented as pairs of def-id and args, and can
/// be normalized, so they are grouped conceptually.
Alias(AliasKind, I::AliasTy),
/// A type parameter; for example, `T` in `fn f<T>(x: T) {}`.
Param(I::ParamTy),
/// Bound type variable, used to represent the `'a` in `for<'a> fn(&'a ())`.
///
/// For canonical queries, we replace inference variables with bound variables,
/// so e.g. when checking whether `&'_ (): Trait<_>` holds, we canonicalize that to
/// `for<'a, T> &'a (): Trait<T>` and then convert the introduced bound variables
/// back to inference variables in a new inference context when inside of the query.
///
/// It is conventional to render anonymous bound types like `^N` or `^D_N`,
/// where `N` is the bound variable's anonymous index into the binder, and
/// `D` is the debruijn index, or totally omitted if the debruijn index is zero.
///
/// See the `rustc-dev-guide` for more details about
/// [higher-ranked trait bounds][1] and [canonical queries][2].
///
/// [1]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
/// [2]: https://rustc-dev-guide.rust-lang.org/traits/canonical-queries.html
Bound(DebruijnIndex, I::BoundTy),
/// A placeholder type, used during higher ranked subtyping to instantiate
/// bound variables.
///
/// It is conventional to render anonymous placeholer types like `!N` or `!U_N`,
/// where `N` is the placeholder variable's anonymous index (which corresponds
/// to the bound variable's index from the binder from which it was instantiated),
/// and `U` is the universe index in which it is instantiated, or totally omitted
/// if the universe index is zero.
Placeholder(I::PlaceholderType),
/// A type variable used during type checking.
///
/// Similar to placeholders, inference variables also live in a universe to
/// correctly deal with higher ranked types. Though unlike placeholders,
/// that universe is stored in the `InferCtxt` instead of directly
/// inside of the type.
Infer(I::InferTy),
/// A placeholder for a type which could not be computed; this is
/// propagated to avoid useless error messages.
Error(I::ErrorGuaranteed),
}
impl<I: Interner> TyKind<I> {
#[inline]
pub fn is_primitive(&self) -> bool {
matches!(self, Bool | Char | Int(_) | Uint(_) | Float(_))
}
}
// This is manually implemented for `TyKind` because `std::mem::discriminant`
// returns an opaque value that is `PartialEq` but not `PartialOrd`
#[inline]
const fn tykind_discriminant<I: Interner>(value: &TyKind<I>) -> usize {
match value {
Bool => 0,
Char => 1,
Int(_) => 2,
Uint(_) => 3,
Float(_) => 4,
Adt(_, _) => 5,
Foreign(_) => 6,
Str => 7,
Array(_, _) => 8,
Slice(_) => 9,
RawPtr(_) => 10,
Ref(_, _, _) => 11,
FnDef(_, _) => 12,
FnPtr(_) => 13,
Dynamic(..) => 14,
Closure(_, _) => 15,
Generator(_, _, _) => 16,
GeneratorWitness(_, _) => 17,
Never => 18,
Tuple(_) => 19,
Alias(_, _) => 20,
Param(_) => 21,
Bound(_, _) => 22,
Placeholder(_) => 23,
Infer(_) => 24,
Error(_) => 25,
}
}
// This is manually implemented because a derive would require `I: Clone`
impl<I: Interner> Clone for TyKind<I> {
fn clone(&self) -> Self {
match self {
Bool => Bool,
Char => Char,
Int(i) => Int(*i),
Uint(u) => Uint(*u),
Float(f) => Float(*f),
Adt(d, s) => Adt(d.clone(), s.clone()),
Foreign(d) => Foreign(d.clone()),
Str => Str,
Array(t, c) => Array(t.clone(), c.clone()),
Slice(t) => Slice(t.clone()),
RawPtr(p) => RawPtr(p.clone()),
Ref(r, t, m) => Ref(r.clone(), t.clone(), m.clone()),
FnDef(d, s) => FnDef(d.clone(), s.clone()),
FnPtr(s) => FnPtr(s.clone()),
Dynamic(p, r, repr) => Dynamic(p.clone(), r.clone(), *repr),
Closure(d, s) => Closure(d.clone(), s.clone()),
Generator(d, s, m) => Generator(d.clone(), s.clone(), m.clone()),
GeneratorWitness(d, s) => GeneratorWitness(d.clone(), s.clone()),
Never => Never,
Tuple(t) => Tuple(t.clone()),
Alias(k, p) => Alias(*k, p.clone()),
Param(p) => Param(p.clone()),
Bound(d, b) => Bound(*d, b.clone()),
Placeholder(p) => Placeholder(p.clone()),
Infer(t) => Infer(t.clone()),
Error(e) => Error(e.clone()),
}
}
}
// This is manually implemented because a derive would require `I: PartialEq`
impl<I: Interner> PartialEq for TyKind<I> {
#[inline]
fn eq(&self, other: &TyKind<I>) -> bool {
// You might expect this `match` to be preceded with this:
//
// tykind_discriminant(self) == tykind_discriminant(other) &&
//
// but the data patterns in practice are such that a comparison
// succeeds 99%+ of the time, and it's faster to omit it.
match (self, other) {
(Int(a_i), Int(b_i)) => a_i == b_i,
(Uint(a_u), Uint(b_u)) => a_u == b_u,
(Float(a_f), Float(b_f)) => a_f == b_f,
(Adt(a_d, a_s), Adt(b_d, b_s)) => a_d == b_d && a_s == b_s,
(Foreign(a_d), Foreign(b_d)) => a_d == b_d,
(Array(a_t, a_c), Array(b_t, b_c)) => a_t == b_t && a_c == b_c,
(Slice(a_t), Slice(b_t)) => a_t == b_t,
(RawPtr(a_t), RawPtr(b_t)) => a_t == b_t,
(Ref(a_r, a_t, a_m), Ref(b_r, b_t, b_m)) => a_r == b_r && a_t == b_t && a_m == b_m,
(FnDef(a_d, a_s), FnDef(b_d, b_s)) => a_d == b_d && a_s == b_s,
(FnPtr(a_s), FnPtr(b_s)) => a_s == b_s,
(Dynamic(a_p, a_r, a_repr), Dynamic(b_p, b_r, b_repr)) => {
a_p == b_p && a_r == b_r && a_repr == b_repr
}
(Closure(a_d, a_s), Closure(b_d, b_s)) => a_d == b_d && a_s == b_s,
(Generator(a_d, a_s, a_m), Generator(b_d, b_s, b_m)) => {
a_d == b_d && a_s == b_s && a_m == b_m
}
(GeneratorWitness(a_d, a_s), GeneratorWitness(b_d, b_s)) => a_d == b_d && a_s == b_s,
(Tuple(a_t), Tuple(b_t)) => a_t == b_t,
(Alias(a_i, a_p), Alias(b_i, b_p)) => a_i == b_i && a_p == b_p,
(Param(a_p), Param(b_p)) => a_p == b_p,
(Bound(a_d, a_b), Bound(b_d, b_b)) => a_d == b_d && a_b == b_b,
(Placeholder(a_p), Placeholder(b_p)) => a_p == b_p,
(Infer(a_t), Infer(b_t)) => a_t == b_t,
(Error(a_e), Error(b_e)) => a_e == b_e,
(Bool, Bool) | (Char, Char) | (Str, Str) | (Never, Never) => true,
_ => {
debug_assert!(
tykind_discriminant(self) != tykind_discriminant(other),
"This branch must be unreachable, maybe the match is missing an arm? self = self = {self:?}, other = {other:?}"
);
false
}
}
}
}
// This is manually implemented because a derive would require `I: Eq`
impl<I: Interner> Eq for TyKind<I> {}
// This is manually implemented because a derive would require `I: PartialOrd`
impl<I: Interner> PartialOrd for TyKind<I> {
#[inline]
fn partial_cmp(&self, other: &TyKind<I>) -> Option<Ordering> {
Some(self.cmp(other))
}
}
// This is manually implemented because a derive would require `I: Ord`
impl<I: Interner> Ord for TyKind<I> {
#[inline]
fn cmp(&self, other: &TyKind<I>) -> Ordering {
tykind_discriminant(self).cmp(&tykind_discriminant(other)).then_with(|| {
match (self, other) {
(Int(a_i), Int(b_i)) => a_i.cmp(b_i),
(Uint(a_u), Uint(b_u)) => a_u.cmp(b_u),
(Float(a_f), Float(b_f)) => a_f.cmp(b_f),
(Adt(a_d, a_s), Adt(b_d, b_s)) => a_d.cmp(b_d).then_with(|| a_s.cmp(b_s)),
(Foreign(a_d), Foreign(b_d)) => a_d.cmp(b_d),
(Array(a_t, a_c), Array(b_t, b_c)) => a_t.cmp(b_t).then_with(|| a_c.cmp(b_c)),
(Slice(a_t), Slice(b_t)) => a_t.cmp(b_t),
(RawPtr(a_t), RawPtr(b_t)) => a_t.cmp(b_t),
(Ref(a_r, a_t, a_m), Ref(b_r, b_t, b_m)) => {
a_r.cmp(b_r).then_with(|| a_t.cmp(b_t).then_with(|| a_m.cmp(b_m)))
}
(FnDef(a_d, a_s), FnDef(b_d, b_s)) => a_d.cmp(b_d).then_with(|| a_s.cmp(b_s)),
(FnPtr(a_s), FnPtr(b_s)) => a_s.cmp(b_s),
(Dynamic(a_p, a_r, a_repr), Dynamic(b_p, b_r, b_repr)) => {
a_p.cmp(b_p).then_with(|| a_r.cmp(b_r).then_with(|| a_repr.cmp(b_repr)))
}
(Closure(a_p, a_s), Closure(b_p, b_s)) => a_p.cmp(b_p).then_with(|| a_s.cmp(b_s)),
(Generator(a_d, a_s, a_m), Generator(b_d, b_s, b_m)) => {
a_d.cmp(b_d).then_with(|| a_s.cmp(b_s).then_with(|| a_m.cmp(b_m)))
}
(
GeneratorWitness(a_d, a_s),
GeneratorWitness(b_d, b_s),
) => match Ord::cmp(a_d, b_d) {
Ordering::Equal => Ord::cmp(a_s, b_s),
cmp => cmp,
},
(Tuple(a_t), Tuple(b_t)) => a_t.cmp(b_t),
(Alias(a_i, a_p), Alias(b_i, b_p)) => a_i.cmp(b_i).then_with(|| a_p.cmp(b_p)),
(Param(a_p), Param(b_p)) => a_p.cmp(b_p),
(Bound(a_d, a_b), Bound(b_d, b_b)) => a_d.cmp(b_d).then_with(|| a_b.cmp(b_b)),
(Placeholder(a_p), Placeholder(b_p)) => a_p.cmp(b_p),
(Infer(a_t), Infer(b_t)) => a_t.cmp(b_t),
(Error(a_e), Error(b_e)) => a_e.cmp(b_e),
(Bool, Bool) | (Char, Char) | (Str, Str) | (Never, Never) => Ordering::Equal,
_ => {
debug_assert!(false, "This branch must be unreachable, maybe the match is missing an arm? self = {self:?}, other = {other:?}");
Ordering::Equal
}
}
})
}
}
// This is manually implemented because a derive would require `I: Hash`
impl<I: Interner> hash::Hash for TyKind<I> {
fn hash<__H: hash::Hasher>(&self, state: &mut __H) -> () {
tykind_discriminant(self).hash(state);
match self {
Int(i) => i.hash(state),
Uint(u) => u.hash(state),
Float(f) => f.hash(state),
Adt(d, s) => {
d.hash(state);
s.hash(state)
}
Foreign(d) => d.hash(state),
Array(t, c) => {
t.hash(state);
c.hash(state)
}
Slice(t) => t.hash(state),
RawPtr(t) => t.hash(state),
Ref(r, t, m) => {
r.hash(state);
t.hash(state);
m.hash(state)
}
FnDef(d, s) => {
d.hash(state);
s.hash(state)
}
FnPtr(s) => s.hash(state),
Dynamic(p, r, repr) => {
p.hash(state);
r.hash(state);
repr.hash(state)
}
Closure(d, s) => {
d.hash(state);
s.hash(state)
}
Generator(d, s, m) => {
d.hash(state);
s.hash(state);
m.hash(state)
}
GeneratorWitness(d, s) => {
d.hash(state);
s.hash(state);
}
Tuple(t) => t.hash(state),
Alias(i, p) => {
i.hash(state);
p.hash(state);
}
Param(p) => p.hash(state),
Bound(d, b) => {
d.hash(state);
b.hash(state)
}
Placeholder(p) => p.hash(state),
Infer(t) => t.hash(state),
Error(e) => e.hash(state),
Bool | Char | Str | Never => (),
}
}
}
impl<I: Interner> DebugWithInfcx<I> for TyKind<I> {
fn fmt<InfCtx: InferCtxtLike<I>>(
this: OptWithInfcx<'_, I, InfCtx, &Self>,
f: &mut core::fmt::Formatter<'_>,
) -> fmt::Result {
match this.data {
Bool => write!(f, "bool"),
Char => write!(f, "char"),
Int(i) => write!(f, "{i:?}"),
Uint(u) => write!(f, "{u:?}"),
Float(float) => write!(f, "{float:?}"),
Adt(d, s) => {
write!(f, "{d:?}")?;
let mut s = s.clone().into_iter();
let first = s.next();
match first {
Some(first) => write!(f, "<{:?}", first)?,
None => return Ok(()),
};
for arg in s {
write!(f, ", {:?}", arg)?;
}
write!(f, ">")
}
Foreign(d) => f.debug_tuple_field1_finish("Foreign", d),
Str => write!(f, "str"),
Array(t, c) => write!(f, "[{:?}; {:?}]", &this.wrap(t), &this.wrap(c)),
Slice(t) => write!(f, "[{:?}]", &this.wrap(t)),
RawPtr(p) => {
let (ty, mutbl) = I::ty_and_mut_to_parts(p.clone());
match I::mutability_is_mut(mutbl) {
true => write!(f, "*mut "),
false => write!(f, "*const "),
}?;
write!(f, "{:?}", &this.wrap(ty))
}
Ref(r, t, m) => match I::mutability_is_mut(m.clone()) {
true => write!(f, "&{:?} mut {:?}", &this.wrap(r), &this.wrap(t)),
false => write!(f, "&{:?} {:?}", &this.wrap(r), &this.wrap(t)),
},
FnDef(d, s) => f.debug_tuple_field2_finish("FnDef", d, &this.wrap(s)),
FnPtr(s) => write!(f, "{:?}", &this.wrap(s)),
Dynamic(p, r, repr) => match repr {
DynKind::Dyn => write!(f, "dyn {:?} + {:?}", &this.wrap(p), &this.wrap(r)),
DynKind::DynStar => {
write!(f, "dyn* {:?} + {:?}", &this.wrap(p), &this.wrap(r))
}
},
Closure(d, s) => f.debug_tuple_field2_finish("Closure", d, &this.wrap(s)),
Generator(d, s, m) => f.debug_tuple_field3_finish("Generator", d, &this.wrap(s), m),
GeneratorWitness(d, s) => {
f.debug_tuple_field2_finish("GeneratorWitness", d, &this.wrap(s))
}
Never => write!(f, "!"),
Tuple(t) => {
write!(f, "(")?;
let mut count = 0;
for ty in t.clone() {
if count > 0 {
write!(f, ", ")?;
}
write!(f, "{:?}", &this.wrap(ty))?;
count += 1;
}
// unary tuples need a trailing comma
if count == 1 {
write!(f, ",")?;
}
write!(f, ")")
}
Alias(i, a) => f.debug_tuple_field2_finish("Alias", i, &this.wrap(a)),
Param(p) => write!(f, "{p:?}"),
Bound(d, b) => crate::debug_bound_var(f, *d, b),
Placeholder(p) => write!(f, "{p:?}"),
Infer(t) => write!(f, "{:?}", this.wrap(t)),
TyKind::Error(_) => write!(f, "{{type error}}"),
}
}
}
// This is manually implemented because a derive would require `I: Debug`
impl<I: Interner> fmt::Debug for TyKind<I> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
OptWithInfcx::new_no_ctx(self).fmt(f)
}
}
// This is manually implemented because a derive would require `I: Encodable`
impl<I: Interner, E: TyEncoder> Encodable<E> for TyKind<I>
where
I::ErrorGuaranteed: Encodable<E>,
I::AdtDef: Encodable<E>,
I::GenericArgsRef: Encodable<E>,
I::DefId: Encodable<E>,
I::Ty: Encodable<E>,
I::Const: Encodable<E>,
I::Region: Encodable<E>,
I::TypeAndMut: Encodable<E>,
I::Mutability: Encodable<E>,
I::Movability: Encodable<E>,
I::PolyFnSig: Encodable<E>,
I::ListBinderExistentialPredicate: Encodable<E>,
I::BinderListTy: Encodable<E>,
I::ListTy: Encodable<E>,
I::AliasTy: Encodable<E>,
I::ParamTy: Encodable<E>,
I::BoundTy: Encodable<E>,
I::PlaceholderType: Encodable<E>,
I::InferTy: Encodable<E>,
I::PredicateKind: Encodable<E>,
I::AllocId: Encodable<E>,
{
fn encode(&self, e: &mut E) {
let disc = tykind_discriminant(self);
match self {
Bool => e.emit_enum_variant(disc, |_| {}),
Char => e.emit_enum_variant(disc, |_| {}),
Int(i) => e.emit_enum_variant(disc, |e| {
i.encode(e);
}),
Uint(u) => e.emit_enum_variant(disc, |e| {
u.encode(e);
}),
Float(f) => e.emit_enum_variant(disc, |e| {
f.encode(e);
}),
Adt(adt, args) => e.emit_enum_variant(disc, |e| {
adt.encode(e);
args.encode(e);
}),
Foreign(def_id) => e.emit_enum_variant(disc, |e| {
def_id.encode(e);
}),
Str => e.emit_enum_variant(disc, |_| {}),
Array(t, c) => e.emit_enum_variant(disc, |e| {
t.encode(e);
c.encode(e);
}),
Slice(t) => e.emit_enum_variant(disc, |e| {
t.encode(e);
}),
RawPtr(tam) => e.emit_enum_variant(disc, |e| {
tam.encode(e);
}),
Ref(r, t, m) => e.emit_enum_variant(disc, |e| {
r.encode(e);
t.encode(e);
m.encode(e);
}),
FnDef(def_id, args) => e.emit_enum_variant(disc, |e| {
def_id.encode(e);
args.encode(e);
}),
FnPtr(polyfnsig) => e.emit_enum_variant(disc, |e| {
polyfnsig.encode(e);
}),
Dynamic(l, r, repr) => e.emit_enum_variant(disc, |e| {
l.encode(e);
r.encode(e);
repr.encode(e);
}),
Closure(def_id, args) => e.emit_enum_variant(disc, |e| {
def_id.encode(e);
args.encode(e);
}),
Generator(def_id, args, m) => e.emit_enum_variant(disc, |e| {
def_id.encode(e);
args.encode(e);
m.encode(e);
}),
GeneratorWitness(def_id, args) => e.emit_enum_variant(disc, |e| {
def_id.encode(e);
args.encode(e);
}),
Never => e.emit_enum_variant(disc, |_| {}),
Tuple(args) => e.emit_enum_variant(disc, |e| {
args.encode(e);
}),
Alias(k, p) => e.emit_enum_variant(disc, |e| {
k.encode(e);
p.encode(e);
}),
Param(p) => e.emit_enum_variant(disc, |e| {
p.encode(e);
}),
Bound(d, b) => e.emit_enum_variant(disc, |e| {
d.encode(e);
b.encode(e);
}),
Placeholder(p) => e.emit_enum_variant(disc, |e| {
p.encode(e);
}),
Infer(i) => e.emit_enum_variant(disc, |e| {
i.encode(e);
}),
Error(d) => e.emit_enum_variant(disc, |e| {
d.encode(e);
}),
}
}
}
// This is manually implemented because a derive would require `I: Decodable`
impl<I: Interner, D: TyDecoder<I = I>> Decodable<D> for TyKind<I>
where
I::ErrorGuaranteed: Decodable<D>,
I::AdtDef: Decodable<D>,
I::GenericArgsRef: Decodable<D>,
I::DefId: Decodable<D>,
I::Ty: Decodable<D>,
I::Const: Decodable<D>,
I::Region: Decodable<D>,
I::TypeAndMut: Decodable<D>,
I::Mutability: Decodable<D>,
I::Movability: Decodable<D>,
I::PolyFnSig: Decodable<D>,
I::ListBinderExistentialPredicate: Decodable<D>,
I::BinderListTy: Decodable<D>,
I::ListTy: Decodable<D>,
I::AliasTy: Decodable<D>,
I::ParamTy: Decodable<D>,
I::AliasTy: Decodable<D>,
I::BoundTy: Decodable<D>,
I::PlaceholderType: Decodable<D>,
I::InferTy: Decodable<D>,
I::PredicateKind: Decodable<D>,
I::AllocId: Decodable<D>,
{
fn decode(d: &mut D) -> Self {
match Decoder::read_usize(d) {
0 => Bool,
1 => Char,
2 => Int(Decodable::decode(d)),
3 => Uint(Decodable::decode(d)),
4 => Float(Decodable::decode(d)),
5 => Adt(Decodable::decode(d), Decodable::decode(d)),
6 => Foreign(Decodable::decode(d)),
7 => Str,
8 => Array(Decodable::decode(d), Decodable::decode(d)),
9 => Slice(Decodable::decode(d)),
10 => RawPtr(Decodable::decode(d)),
11 => Ref(Decodable::decode(d), Decodable::decode(d), Decodable::decode(d)),
12 => FnDef(Decodable::decode(d), Decodable::decode(d)),
13 => FnPtr(Decodable::decode(d)),
14 => Dynamic(Decodable::decode(d), Decodable::decode(d), Decodable::decode(d)),
15 => Closure(Decodable::decode(d), Decodable::decode(d)),
16 => Generator(Decodable::decode(d), Decodable::decode(d), Decodable::decode(d)),
17 => GeneratorWitness(Decodable::decode(d), Decodable::decode(d)),
18 => Never,
19 => Tuple(Decodable::decode(d)),
20 => Alias(Decodable::decode(d), Decodable::decode(d)),
21 => Param(Decodable::decode(d)),
22 => Bound(Decodable::decode(d), Decodable::decode(d)),
23 => Placeholder(Decodable::decode(d)),
24 => Infer(Decodable::decode(d)),
25 => Error(Decodable::decode(d)),
_ => panic!(
"{}",
format!(
"invalid enum variant tag while decoding `{}`, expected 0..{}",
"TyKind", 26,
)
),
}
}
}
// This is not a derived impl because a derive would require `I: HashStable`
#[allow(rustc::usage_of_ty_tykind)]
impl<CTX: HashStableContext, I: Interner> HashStable<CTX> for TyKind<I>
where
I::AdtDef: HashStable<CTX>,
I::DefId: HashStable<CTX>,
I::GenericArgsRef: HashStable<CTX>,
I::Ty: HashStable<CTX>,
I::Const: HashStable<CTX>,
I::TypeAndMut: HashStable<CTX>,
I::PolyFnSig: HashStable<CTX>,
I::ListBinderExistentialPredicate: HashStable<CTX>,
I::Region: HashStable<CTX>,
I::Movability: HashStable<CTX>,
I::Mutability: HashStable<CTX>,
I::BinderListTy: HashStable<CTX>,
I::ListTy: HashStable<CTX>,
I::AliasTy: HashStable<CTX>,
I::BoundTy: HashStable<CTX>,
I::ParamTy: HashStable<CTX>,
I::PlaceholderType: HashStable<CTX>,
I::InferTy: HashStable<CTX>,
I::ErrorGuaranteed: HashStable<CTX>,
{
#[inline]
fn hash_stable(
&self,
__hcx: &mut CTX,
__hasher: &mut rustc_data_structures::stable_hasher::StableHasher,
) {
std::mem::discriminant(self).hash_stable(__hcx, __hasher);
match self {
Bool => {}
Char => {}
Int(i) => {
i.hash_stable(__hcx, __hasher);
}
Uint(u) => {
u.hash_stable(__hcx, __hasher);
}
Float(f) => {
f.hash_stable(__hcx, __hasher);
}
Adt(adt, args) => {
adt.hash_stable(__hcx, __hasher);
args.hash_stable(__hcx, __hasher);
}
Foreign(def_id) => {
def_id.hash_stable(__hcx, __hasher);
}
Str => {}
Array(t, c) => {
t.hash_stable(__hcx, __hasher);
c.hash_stable(__hcx, __hasher);
}
Slice(t) => {
t.hash_stable(__hcx, __hasher);
}
RawPtr(tam) => {
tam.hash_stable(__hcx, __hasher);
}
Ref(r, t, m) => {
r.hash_stable(__hcx, __hasher);
t.hash_stable(__hcx, __hasher);
m.hash_stable(__hcx, __hasher);
}
FnDef(def_id, args) => {
def_id.hash_stable(__hcx, __hasher);
args.hash_stable(__hcx, __hasher);
}
FnPtr(polyfnsig) => {
polyfnsig.hash_stable(__hcx, __hasher);
}
Dynamic(l, r, repr) => {
l.hash_stable(__hcx, __hasher);
r.hash_stable(__hcx, __hasher);
repr.hash_stable(__hcx, __hasher);
}
Closure(def_id, args) => {
def_id.hash_stable(__hcx, __hasher);
args.hash_stable(__hcx, __hasher);
}
Generator(def_id, args, m) => {
def_id.hash_stable(__hcx, __hasher);
args.hash_stable(__hcx, __hasher);
m.hash_stable(__hcx, __hasher);
}
GeneratorWitness(def_id, args) => {
def_id.hash_stable(__hcx, __hasher);
args.hash_stable(__hcx, __hasher);
}
Never => {}
Tuple(args) => {
args.hash_stable(__hcx, __hasher);
}
Alias(k, p) => {
k.hash_stable(__hcx, __hasher);
p.hash_stable(__hcx, __hasher);
}
Param(p) => {
p.hash_stable(__hcx, __hasher);
}
Bound(d, b) => {
d.hash_stable(__hcx, __hasher);
b.hash_stable(__hcx, __hasher);
}
Placeholder(p) => {
p.hash_stable(__hcx, __hasher);
}
Infer(i) => {
i.hash_stable(__hcx, __hasher);
}
Error(d) => {
d.hash_stable(__hcx, __hasher);
}
}
}
}
/// Represents a constant in Rust.
// #[derive(derive_more::From)]
pub enum ConstKind<I: Interner> {
/// A const generic parameter.
Param(I::ParamConst),
/// Infer the value of the const.
Infer(I::InferConst),
/// Bound const variable, used only when preparing a trait query.
Bound(DebruijnIndex, I::BoundConst),
/// A placeholder const - universally quantified higher-ranked const.
Placeholder(I::PlaceholderConst),
/// An unnormalized const item such as an anon const or assoc const or free const item.
/// Right now anything other than anon consts does not actually work properly but this
/// should
Unevaluated(I::AliasConst),
/// Used to hold computed value.
Value(I::ValueConst),
/// A placeholder for a const which could not be computed; this is
/// propagated to avoid useless error messages.
Error(I::ErrorGuaranteed),
/// Unevaluated non-const-item, used by `feature(generic_const_exprs)` to represent
/// const arguments such as `N + 1` or `foo(N)`
Expr(I::ExprConst),
}
const fn const_kind_discriminant<I: Interner>(value: &ConstKind<I>) -> usize {
match value {
ConstKind::Param(_) => 0,
ConstKind::Infer(_) => 1,
ConstKind::Bound(_, _) => 2,
ConstKind::Placeholder(_) => 3,
ConstKind::Unevaluated(_) => 4,
ConstKind::Value(_) => 5,
ConstKind::Error(_) => 6,
ConstKind::Expr(_) => 7,
}
}
impl<I: Interner> hash::Hash for ConstKind<I> {
fn hash<H: hash::Hasher>(&self, state: &mut H) {
const_kind_discriminant(self).hash(state);
match self {
ConstKind::Param(p) => p.hash(state),
ConstKind::Infer(i) => i.hash(state),
ConstKind::Bound(d, b) => {
d.hash(state);
b.hash(state);
}
ConstKind::Placeholder(p) => p.hash(state),
ConstKind::Unevaluated(u) => u.hash(state),
ConstKind::Value(v) => v.hash(state),
ConstKind::Error(e) => e.hash(state),
ConstKind::Expr(e) => e.hash(state),
}
}
}
impl<CTX: HashStableContext, I: Interner> HashStable<CTX> for ConstKind<I>
where
I::ParamConst: HashStable<CTX>,
I::InferConst: HashStable<CTX>,
I::BoundConst: HashStable<CTX>,
I::PlaceholderConst: HashStable<CTX>,
I::AliasConst: HashStable<CTX>,
I::ValueConst: HashStable<CTX>,
I::ErrorGuaranteed: HashStable<CTX>,
I::ExprConst: HashStable<CTX>,
{
fn hash_stable(
&self,
hcx: &mut CTX,
hasher: &mut rustc_data_structures::stable_hasher::StableHasher,
) {
const_kind_discriminant(self).hash_stable(hcx, hasher);
match self {
ConstKind::Param(p) => p.hash_stable(hcx, hasher),
ConstKind::Infer(i) => i.hash_stable(hcx, hasher),
ConstKind::Bound(d, b) => {
d.hash_stable(hcx, hasher);
b.hash_stable(hcx, hasher);
}
ConstKind::Placeholder(p) => p.hash_stable(hcx, hasher),
ConstKind::Unevaluated(u) => u.hash_stable(hcx, hasher),
ConstKind::Value(v) => v.hash_stable(hcx, hasher),
ConstKind::Error(e) => e.hash_stable(hcx, hasher),
ConstKind::Expr(e) => e.hash_stable(hcx, hasher),
}
}
}
impl<I: Interner, D: TyDecoder<I = I>> Decodable<D> for ConstKind<I>
where
I::ParamConst: Decodable<D>,
I::InferConst: Decodable<D>,
I::BoundConst: Decodable<D>,
I::PlaceholderConst: Decodable<D>,
I::AliasConst: Decodable<D>,
I::ValueConst: Decodable<D>,
I::ErrorGuaranteed: Decodable<D>,
I::ExprConst: Decodable<D>,
{
fn decode(d: &mut D) -> Self {
match Decoder::read_usize(d) {
0 => ConstKind::Param(Decodable::decode(d)),
1 => ConstKind::Infer(Decodable::decode(d)),
2 => ConstKind::Bound(Decodable::decode(d), Decodable::decode(d)),
3 => ConstKind::Placeholder(Decodable::decode(d)),
4 => ConstKind::Unevaluated(Decodable::decode(d)),
5 => ConstKind::Value(Decodable::decode(d)),
6 => ConstKind::Error(Decodable::decode(d)),
7 => ConstKind::Expr(Decodable::decode(d)),
_ => panic!(
"{}",
format!(
"invalid enum variant tag while decoding `{}`, expected 0..{}",
"ConstKind", 8,
)
),
}
}
}
impl<I: Interner, E: TyEncoder<I = I>> Encodable<E> for ConstKind<I>
where
I::ParamConst: Encodable<E>,
I::InferConst: Encodable<E>,
I::BoundConst: Encodable<E>,
I::PlaceholderConst: Encodable<E>,
I::AliasConst: Encodable<E>,
I::ValueConst: Encodable<E>,
I::ErrorGuaranteed: Encodable<E>,
I::ExprConst: Encodable<E>,
{
fn encode(&self, e: &mut E) {
let disc = const_kind_discriminant(self);
match self {
ConstKind::Param(p) => e.emit_enum_variant(disc, |e| p.encode(e)),
ConstKind::Infer(i) => e.emit_enum_variant(disc, |e| i.encode(e)),
ConstKind::Bound(d, b) => e.emit_enum_variant(disc, |e| {
d.encode(e);
b.encode(e);
}),
ConstKind::Placeholder(p) => e.emit_enum_variant(disc, |e| p.encode(e)),
ConstKind::Unevaluated(u) => e.emit_enum_variant(disc, |e| u.encode(e)),
ConstKind::Value(v) => e.emit_enum_variant(disc, |e| v.encode(e)),
ConstKind::Error(er) => e.emit_enum_variant(disc, |e| er.encode(e)),
ConstKind::Expr(ex) => e.emit_enum_variant(disc, |e| ex.encode(e)),
}
}
}
impl<I: Interner> PartialOrd for ConstKind<I> {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl<I: Interner> Ord for ConstKind<I> {
fn cmp(&self, other: &Self) -> Ordering {
const_kind_discriminant(self)
.cmp(&const_kind_discriminant(other))
.then_with(|| match (self, other) {
(ConstKind::Param(p1), ConstKind::Param(p2)) => p1.cmp(p2),
(ConstKind::Infer(i1), ConstKind::Infer(i2)) => i1.cmp(i2),
(ConstKind::Bound(d1, b1), ConstKind::Bound(d2, b2)) => d1.cmp(d2).then_with(|| b1.cmp(b2)),
(ConstKind::Placeholder(p1), ConstKind::Placeholder(p2)) => p1.cmp(p2),
(ConstKind::Unevaluated(u1), ConstKind::Unevaluated(u2)) => u1.cmp(u2),
(ConstKind::Value(v1), ConstKind::Value(v2)) => v1.cmp(v2),
(ConstKind::Error(e1), ConstKind::Error(e2)) => e1.cmp(e2),
(ConstKind::Expr(e1), ConstKind::Expr(e2)) => e1.cmp(e2),
_ => {
debug_assert!(false, "This branch must be unreachable, maybe the match is missing an arm? self = {self:?}, other = {other:?}");
Ordering::Equal
}
})
}
}
impl<I: Interner> PartialEq for ConstKind<I> {
fn eq(&self, other: &Self) -> bool {
match (self, other) {
(Self::Param(l0), Self::Param(r0)) => l0 == r0,
(Self::Infer(l0), Self::Infer(r0)) => l0 == r0,
(Self::Bound(l0, l1), Self::Bound(r0, r1)) => l0 == r0 && l1 == r1,
(Self::Placeholder(l0), Self::Placeholder(r0)) => l0 == r0,
(Self::Unevaluated(l0), Self::Unevaluated(r0)) => l0 == r0,
(Self::Value(l0), Self::Value(r0)) => l0 == r0,
(Self::Error(l0), Self::Error(r0)) => l0 == r0,
(Self::Expr(l0), Self::Expr(r0)) => l0 == r0,
_ => false,
}
}
}
impl<I: Interner> Eq for ConstKind<I> {}
impl<I: Interner> Clone for ConstKind<I> {
fn clone(&self) -> Self {
match self {
Self::Param(arg0) => Self::Param(arg0.clone()),
Self::Infer(arg0) => Self::Infer(arg0.clone()),
Self::Bound(arg0, arg1) => Self::Bound(arg0.clone(), arg1.clone()),
Self::Placeholder(arg0) => Self::Placeholder(arg0.clone()),
Self::Unevaluated(arg0) => Self::Unevaluated(arg0.clone()),
Self::Value(arg0) => Self::Value(arg0.clone()),
Self::Error(arg0) => Self::Error(arg0.clone()),
Self::Expr(arg0) => Self::Expr(arg0.clone()),
}
}
}
/// Representation of regions. Note that the NLL checker uses a distinct
/// representation of regions. For this reason, it internally replaces all the
/// regions with inference variables -- the index of the variable is then used
/// to index into internal NLL data structures. See `rustc_const_eval::borrow_check`
/// module for more information.
///
/// Note: operations are on the wrapper `Region` type, which is interned,
/// rather than this type.
///
/// ## The Region lattice within a given function
///
/// In general, the region lattice looks like
///
/// ```text
/// static ----------+-----...------+ (greatest)
/// | | |
/// early-bound and | |
/// free regions | |
/// | | |
/// | | |
/// empty(root) placeholder(U1) |
/// | / |
/// | / placeholder(Un)
/// empty(U1) -- /
/// | /
/// ... /
/// | /
/// empty(Un) -------- (smallest)
/// ```
///
/// Early-bound/free regions are the named lifetimes in scope from the
/// function declaration. They have relationships to one another
/// determined based on the declared relationships from the
/// function.
///
/// Note that inference variables and bound regions are not included
/// in this diagram. In the case of inference variables, they should
/// be inferred to some other region from the diagram. In the case of
/// bound regions, they are excluded because they don't make sense to
/// include -- the diagram indicates the relationship between free
/// regions.
///
/// ## Inference variables
///
/// During region inference, we sometimes create inference variables,
/// represented as `ReVar`. These will be inferred by the code in
/// `infer::lexical_region_resolve` to some free region from the
/// lattice above (the minimal region that meets the
/// constraints).
///
/// During NLL checking, where regions are defined differently, we
/// also use `ReVar` -- in that case, the index is used to index into
/// the NLL region checker's data structures. The variable may in fact
/// represent either a free region or an inference variable, in that
/// case.
///
/// ## Bound Regions
///
/// These are regions that are stored behind a binder and must be substituted
/// with some concrete region before being used. There are two kind of
/// bound regions: early-bound, which are bound in an item's `Generics`,
/// and are substituted by an `GenericArgs`, and late-bound, which are part of
/// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
/// the likes of `liberate_late_bound_regions`. The distinction exists
/// because higher-ranked lifetimes aren't supported in all places. See [1][2].
///
/// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
/// outside their binder, e.g., in types passed to type inference, and
/// should first be substituted (by placeholder regions, free regions,
/// or region variables).
///
/// ## Placeholder and Free Regions
///
/// One often wants to work with bound regions without knowing their precise
/// identity. For example, when checking a function, the lifetime of a borrow
/// can end up being assigned to some region parameter. In these cases,
/// it must be ensured that bounds on the region can't be accidentally
/// assumed without being checked.
///
/// To do this, we replace the bound regions with placeholder markers,
/// which don't satisfy any relation not explicitly provided.
///
/// There are two kinds of placeholder regions in rustc: `ReFree` and
/// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
/// to be used. These also support explicit bounds: both the internally-stored
/// *scope*, which the region is assumed to outlive, as well as other
/// relations stored in the `FreeRegionMap`. Note that these relations
/// aren't checked when you `make_subregion` (or `eq_types`), only by
/// `resolve_regions_and_report_errors`.
///
/// When working with higher-ranked types, some region relations aren't
/// yet known, so you can't just call `resolve_regions_and_report_errors`.
/// `RePlaceholder` is designed for this purpose. In these contexts,
/// there's also the risk that some inference variable laying around will
/// get unified with your placeholder region: if you want to check whether
/// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
/// with a placeholder region `'%a`, the variable `'_` would just be
/// instantiated to the placeholder region `'%a`, which is wrong because
/// the inference variable is supposed to satisfy the relation
/// *for every value of the placeholder region*. To ensure that doesn't
/// happen, you can use `leak_check`. This is more clearly explained
/// by the [rustc dev guide].
///
/// [1]: https://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
/// [2]: https://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
/// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
pub enum RegionKind<I: Interner> {
/// Region bound in a type or fn declaration which will be
/// substituted 'early' -- that is, at the same time when type
/// parameters are substituted.
ReEarlyBound(I::EarlyBoundRegion),
/// Region bound in a function scope, which will be substituted when the
/// function is called.
ReLateBound(DebruijnIndex, I::BoundRegion),
/// When checking a function body, the types of all arguments and so forth
/// that refer to bound region parameters are modified to refer to free
/// region parameters.
ReFree(I::FreeRegion),
/// Static data that has an "infinite" lifetime. Top in the region lattice.
ReStatic,
/// A region variable. Should not exist outside of type inference.
ReVar(I::RegionVid),
/// A placeholder region -- basically, the higher-ranked version of `ReFree`.
/// Should not exist outside of type inference.
RePlaceholder(I::PlaceholderRegion),
/// Erased region, used by trait selection, in MIR and during codegen.
ReErased,
/// A region that resulted from some other error. Used exclusively for diagnostics.
ReError(I::ErrorGuaranteed),
}
// This is manually implemented for `RegionKind` because `std::mem::discriminant`
// returns an opaque value that is `PartialEq` but not `PartialOrd`
#[inline]
const fn regionkind_discriminant<I: Interner>(value: &RegionKind<I>) -> usize {
match value {
ReEarlyBound(_) => 0,
ReLateBound(_, _) => 1,
ReFree(_) => 2,
ReStatic => 3,
ReVar(_) => 4,
RePlaceholder(_) => 5,
ReErased => 6,
ReError(_) => 7,
}
}
// This is manually implemented because a derive would require `I: Copy`
impl<I: Interner> Copy for RegionKind<I>
where
I::EarlyBoundRegion: Copy,
I::BoundRegion: Copy,
I::FreeRegion: Copy,
I::RegionVid: Copy,
I::PlaceholderRegion: Copy,
I::ErrorGuaranteed: Copy,
{
}
// This is manually implemented because a derive would require `I: Clone`
impl<I: Interner> Clone for RegionKind<I> {
fn clone(&self) -> Self {
match self {
ReEarlyBound(r) => ReEarlyBound(r.clone()),
ReLateBound(d, r) => ReLateBound(*d, r.clone()),
ReFree(r) => ReFree(r.clone()),
ReStatic => ReStatic,
ReVar(r) => ReVar(r.clone()),
RePlaceholder(r) => RePlaceholder(r.clone()),
ReErased => ReErased,
ReError(r) => ReError(r.clone()),
}
}
}
// This is manually implemented because a derive would require `I: PartialEq`
impl<I: Interner> PartialEq for RegionKind<I> {
#[inline]
fn eq(&self, other: &RegionKind<I>) -> bool {
regionkind_discriminant(self) == regionkind_discriminant(other)
&& match (self, other) {
(ReEarlyBound(a_r), ReEarlyBound(b_r)) => a_r == b_r,
(ReLateBound(a_d, a_r), ReLateBound(b_d, b_r)) => a_d == b_d && a_r == b_r,
(ReFree(a_r), ReFree(b_r)) => a_r == b_r,
(ReStatic, ReStatic) => true,
(ReVar(a_r), ReVar(b_r)) => a_r == b_r,
(RePlaceholder(a_r), RePlaceholder(b_r)) => a_r == b_r,
(ReErased, ReErased) => true,
(ReError(_), ReError(_)) => true,
_ => {
debug_assert!(
false,
"This branch must be unreachable, maybe the match is missing an arm? self = {self:?}, other = {other:?}"
);
true
}
}
}
}
// This is manually implemented because a derive would require `I: Eq`
impl<I: Interner> Eq for RegionKind<I> {}
// This is manually implemented because a derive would require `I: PartialOrd`
impl<I: Interner> PartialOrd for RegionKind<I> {
#[inline]
fn partial_cmp(&self, other: &RegionKind<I>) -> Option<Ordering> {
Some(self.cmp(other))
}
}
// This is manually implemented because a derive would require `I: Ord`
impl<I: Interner> Ord for RegionKind<I> {
#[inline]
fn cmp(&self, other: &RegionKind<I>) -> Ordering {
regionkind_discriminant(self).cmp(®ionkind_discriminant(other)).then_with(|| {
match (self, other) {
(ReEarlyBound(a_r), ReEarlyBound(b_r)) => a_r.cmp(b_r),
(ReLateBound(a_d, a_r), ReLateBound(b_d, b_r)) => {
a_d.cmp(b_d).then_with(|| a_r.cmp(b_r))
}
(ReFree(a_r), ReFree(b_r)) => a_r.cmp(b_r),
(ReStatic, ReStatic) => Ordering::Equal,
(ReVar(a_r), ReVar(b_r)) => a_r.cmp(b_r),
(RePlaceholder(a_r), RePlaceholder(b_r)) => a_r.cmp(b_r),
(ReErased, ReErased) => Ordering::Equal,
_ => {
debug_assert!(false, "This branch must be unreachable, maybe the match is missing an arm? self = self = {self:?}, other = {other:?}");
Ordering::Equal
}
}
})
}
}
// This is manually implemented because a derive would require `I: Hash`
impl<I: Interner> hash::Hash for RegionKind<I> {
fn hash<H: hash::Hasher>(&self, state: &mut H) -> () {
regionkind_discriminant(self).hash(state);
match self {
ReEarlyBound(r) => r.hash(state),
ReLateBound(d, r) => {
d.hash(state);
r.hash(state)
}
ReFree(r) => r.hash(state),
ReStatic => (),
ReVar(r) => r.hash(state),
RePlaceholder(r) => r.hash(state),
ReErased => (),
ReError(_) => (),
}
}
}
impl<I: Interner> DebugWithInfcx<I> for RegionKind<I> {
fn fmt<InfCtx: InferCtxtLike<I>>(
this: OptWithInfcx<'_, I, InfCtx, &Self>,
f: &mut core::fmt::Formatter<'_>,
) -> core::fmt::Result {
match this.data {
ReEarlyBound(data) => write!(f, "ReEarlyBound({data:?})"),
ReLateBound(binder_id, bound_region) => {
write!(f, "ReLateBound({binder_id:?}, {bound_region:?})")
}
ReFree(fr) => write!(f, "{fr:?}"),
ReStatic => f.write_str("ReStatic"),
ReVar(vid) => write!(f, "{:?}", &this.wrap(vid)),
RePlaceholder(placeholder) => write!(f, "RePlaceholder({placeholder:?})"),
ReErased => f.write_str("ReErased"),
ReError(_) => f.write_str("ReError"),
}
}
}
impl<I: Interner> fmt::Debug for RegionKind<I> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
OptWithInfcx::new_no_ctx(self).fmt(f)
}
}
// This is manually implemented because a derive would require `I: Encodable`
impl<I: Interner, E: TyEncoder> Encodable<E> for RegionKind<I>
where
I::EarlyBoundRegion: Encodable<E>,
I::BoundRegion: Encodable<E>,
I::FreeRegion: Encodable<E>,
I::RegionVid: Encodable<E>,
I::PlaceholderRegion: Encodable<E>,
{
fn encode(&self, e: &mut E) {
let disc = regionkind_discriminant(self);
match self {
ReEarlyBound(a) => e.emit_enum_variant(disc, |e| {
a.encode(e);
}),
ReLateBound(a, b) => e.emit_enum_variant(disc, |e| {
a.encode(e);
b.encode(e);
}),
ReFree(a) => e.emit_enum_variant(disc, |e| {
a.encode(e);
}),
ReStatic => e.emit_enum_variant(disc, |_| {}),
ReVar(a) => e.emit_enum_variant(disc, |e| {
a.encode(e);
}),
RePlaceholder(a) => e.emit_enum_variant(disc, |e| {
a.encode(e);
}),
ReErased => e.emit_enum_variant(disc, |_| {}),
ReError(_) => e.emit_enum_variant(disc, |_| {}),
}
}
}
// This is manually implemented because a derive would require `I: Decodable`
impl<I: Interner, D: TyDecoder<I = I>> Decodable<D> for RegionKind<I>
where
I::EarlyBoundRegion: Decodable<D>,
I::BoundRegion: Decodable<D>,
I::FreeRegion: Decodable<D>,
I::RegionVid: Decodable<D>,
I::PlaceholderRegion: Decodable<D>,
I::ErrorGuaranteed: Decodable<D>,
{
fn decode(d: &mut D) -> Self {
match Decoder::read_usize(d) {
0 => ReEarlyBound(Decodable::decode(d)),
1 => ReLateBound(Decodable::decode(d), Decodable::decode(d)),
2 => ReFree(Decodable::decode(d)),
3 => ReStatic,
4 => ReVar(Decodable::decode(d)),
5 => RePlaceholder(Decodable::decode(d)),
6 => ReErased,
7 => ReError(Decodable::decode(d)),
_ => panic!(
"{}",
format!(
"invalid enum variant tag while decoding `{}`, expected 0..{}",
"RegionKind", 8,
)
),
}
}
}
// This is not a derived impl because a derive would require `I: HashStable`
impl<CTX: HashStableContext, I: Interner> HashStable<CTX> for RegionKind<I>
where
I::EarlyBoundRegion: HashStable<CTX>,
I::BoundRegion: HashStable<CTX>,
I::FreeRegion: HashStable<CTX>,
I::RegionVid: HashStable<CTX>,
I::PlaceholderRegion: HashStable<CTX>,
{
#[inline]
fn hash_stable(
&self,
hcx: &mut CTX,
hasher: &mut rustc_data_structures::stable_hasher::StableHasher,
) {
std::mem::discriminant(self).hash_stable(hcx, hasher);
match self {
ReErased | ReStatic | ReError(_) => {
// No variant fields to hash for these ...
}
ReLateBound(d, r) => {
d.hash_stable(hcx, hasher);
r.hash_stable(hcx, hasher);
}
ReEarlyBound(r) => {
r.hash_stable(hcx, hasher);
}
ReFree(r) => {
r.hash_stable(hcx, hasher);
}
RePlaceholder(r) => {
r.hash_stable(hcx, hasher);
}
ReVar(_) => {
panic!("region variables should not be hashed: {self:?}")
}
}
}
}