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 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581
//! Machinery for hygienic macros.
//!
//! Inspired by Matthew Flatt et al., “Macros That Work Together: Compile-Time Bindings, Partial
//! Expansion, and Definition Contexts,” *Journal of Functional Programming* 22, no. 2
//! (March 1, 2012): 181–216, <https://doi.org/10.1017/S0956796812000093>.
// Hygiene data is stored in a global variable and accessed via TLS, which
// means that accesses are somewhat expensive. (`HygieneData::with`
// encapsulates a single access.) Therefore, on hot code paths it is worth
// ensuring that multiple HygieneData accesses are combined into a single
// `HygieneData::with`.
//
// This explains why `HygieneData`, `SyntaxContext` and `ExpnId` have interfaces
// with a certain amount of redundancy in them. For example,
// `SyntaxContext::outer_expn_data` combines `SyntaxContext::outer` and
// `ExpnId::expn_data` so that two `HygieneData` accesses can be performed within
// a single `HygieneData::with` call.
//
// It also explains why many functions appear in `HygieneData` and again in
// `SyntaxContext` or `ExpnId`. For example, `HygieneData::outer` and
// `SyntaxContext::outer` do the same thing, but the former is for use within a
// `HygieneData::with` call while the latter is for use outside such a call.
// When modifying this file it is important to understand this distinction,
// because getting it wrong can lead to nested `HygieneData::with` calls that
// trigger runtime aborts. (Fortunately these are obvious and easy to fix.)
use crate::edition::Edition;
use crate::symbol::{kw, sym, Symbol};
use crate::with_session_globals;
use crate::{HashStableContext, Span, DUMMY_SP};
use crate::def_id::{CrateNum, DefId, StableCrateId, CRATE_DEF_ID, LOCAL_CRATE};
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::stable_hasher::HashingControls;
use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher};
use rustc_data_structures::sync::{Lock, Lrc, WorkerLocal};
use rustc_data_structures::unhash::UnhashMap;
use rustc_index::IndexVec;
use rustc_macros::HashStable_Generic;
use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
use std::cell::RefCell;
use std::collections::hash_map::Entry;
use std::fmt;
use std::hash::Hash;
/// A `SyntaxContext` represents a chain of pairs `(ExpnId, Transparency)` named "marks".
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct SyntaxContext(u32);
#[derive(Debug, Encodable, Decodable, Clone)]
pub struct SyntaxContextData {
outer_expn: ExpnId,
outer_transparency: Transparency,
parent: SyntaxContext,
/// This context, but with all transparent and semi-transparent expansions filtered away.
opaque: SyntaxContext,
/// This context, but with all transparent expansions filtered away.
opaque_and_semitransparent: SyntaxContext,
/// Name of the crate to which `$crate` with this context would resolve.
dollar_crate_name: Symbol,
}
rustc_index::newtype_index! {
/// A unique ID associated with a macro invocation and expansion.
#[custom_encodable]
pub struct ExpnIndex {}
}
/// A unique ID associated with a macro invocation and expansion.
#[derive(Clone, Copy, PartialEq, Eq, Hash)]
pub struct ExpnId {
pub krate: CrateNum,
pub local_id: ExpnIndex,
}
impl fmt::Debug for ExpnId {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// Generate crate_::{{expn_}}.
write!(f, "{:?}::{{{{expn{}}}}}", self.krate, self.local_id.as_u32())
}
}
rustc_index::newtype_index! {
/// A unique ID associated with a macro invocation and expansion.
#[custom_encodable]
#[no_ord_impl]
#[debug_format = "expn{}"]
pub struct LocalExpnId {}
}
// To ensure correctness of incremental compilation,
// `LocalExpnId` must not implement `Ord` or `PartialOrd`.
// See https://github.com/rust-lang/rust/issues/90317.
impl !Ord for LocalExpnId {}
impl !PartialOrd for LocalExpnId {}
/// Assert that the provided `HashStableContext` is configured with the 'default'
/// `HashingControls`. We should always have bailed out before getting to here
/// with a non-default mode. With this check in place, we can avoid the need
/// to maintain separate versions of `ExpnData` hashes for each permutation
/// of `HashingControls` settings.
fn assert_default_hashing_controls<CTX: HashStableContext>(ctx: &CTX, msg: &str) {
match ctx.hashing_controls() {
// Note that we require that `hash_spans` be set according to the global
// `-Z incremental-ignore-spans` option. Normally, this option is disabled,
// which will cause us to require that this method always be called with `Span` hashing
// enabled.
//
// Span hashing can also be disabled without `-Z incremental-ignore-spans`.
// This is the case for instance when building a hash for name mangling.
// Such configuration must not be used for metadata.
HashingControls { hash_spans }
if hash_spans != ctx.unstable_opts_incremental_ignore_spans() => {}
other => panic!("Attempted hashing of {msg} with non-default HashingControls: {other:?}"),
}
}
/// A unique hash value associated to an expansion.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, Encodable, Decodable, HashStable_Generic)]
pub struct ExpnHash(Fingerprint);
impl ExpnHash {
/// Returns the [StableCrateId] identifying the crate this [ExpnHash]
/// originates from.
#[inline]
pub fn stable_crate_id(self) -> StableCrateId {
StableCrateId(self.0.split().0)
}
/// Returns the crate-local part of the [ExpnHash].
///
/// Used for tests.
#[inline]
pub fn local_hash(self) -> Hash64 {
self.0.split().1
}
#[inline]
pub fn is_root(self) -> bool {
self.0 == Fingerprint::ZERO
}
/// Builds a new [ExpnHash] with the given [StableCrateId] and
/// `local_hash`, where `local_hash` must be unique within its crate.
fn new(stable_crate_id: StableCrateId, local_hash: Hash64) -> ExpnHash {
ExpnHash(Fingerprint::new(stable_crate_id.0, local_hash))
}
}
/// A property of a macro expansion that determines how identifiers
/// produced by that expansion are resolved.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Hash, Debug, Encodable, Decodable)]
#[derive(HashStable_Generic)]
pub enum Transparency {
/// Identifier produced by a transparent expansion is always resolved at call-site.
/// Call-site spans in procedural macros, hygiene opt-out in `macro` should use this.
Transparent,
/// Identifier produced by a semi-transparent expansion may be resolved
/// either at call-site or at definition-site.
/// If it's a local variable, label or `$crate` then it's resolved at def-site.
/// Otherwise it's resolved at call-site.
/// `macro_rules` macros behave like this, built-in macros currently behave like this too,
/// but that's an implementation detail.
SemiTransparent,
/// Identifier produced by an opaque expansion is always resolved at definition-site.
/// Def-site spans in procedural macros, identifiers from `macro` by default use this.
Opaque,
}
impl LocalExpnId {
/// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
pub const ROOT: LocalExpnId = LocalExpnId::from_u32(0);
#[inline]
pub fn from_raw(idx: ExpnIndex) -> LocalExpnId {
LocalExpnId::from_u32(idx.as_u32())
}
#[inline]
pub fn as_raw(self) -> ExpnIndex {
ExpnIndex::from_u32(self.as_u32())
}
pub fn fresh_empty() -> LocalExpnId {
HygieneData::with(|data| {
let expn_id = data.local_expn_data.push(None);
let _eid = data.local_expn_hashes.push(ExpnHash(Fingerprint::ZERO));
debug_assert_eq!(expn_id, _eid);
expn_id
})
}
pub fn fresh(mut expn_data: ExpnData, ctx: impl HashStableContext) -> LocalExpnId {
debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
let expn_hash = update_disambiguator(&mut expn_data, ctx);
HygieneData::with(|data| {
let expn_id = data.local_expn_data.push(Some(expn_data));
let _eid = data.local_expn_hashes.push(expn_hash);
debug_assert_eq!(expn_id, _eid);
let _old_id = data.expn_hash_to_expn_id.insert(expn_hash, expn_id.to_expn_id());
debug_assert!(_old_id.is_none());
expn_id
})
}
#[inline]
pub fn expn_hash(self) -> ExpnHash {
HygieneData::with(|data| data.local_expn_hash(self))
}
#[inline]
pub fn expn_data(self) -> ExpnData {
HygieneData::with(|data| data.local_expn_data(self).clone())
}
#[inline]
pub fn to_expn_id(self) -> ExpnId {
ExpnId { krate: LOCAL_CRATE, local_id: self.as_raw() }
}
#[inline]
pub fn set_expn_data(self, mut expn_data: ExpnData, ctx: impl HashStableContext) {
debug_assert_eq!(expn_data.parent.krate, LOCAL_CRATE);
let expn_hash = update_disambiguator(&mut expn_data, ctx);
HygieneData::with(|data| {
let old_expn_data = &mut data.local_expn_data[self];
assert!(old_expn_data.is_none(), "expansion data is reset for an expansion ID");
*old_expn_data = Some(expn_data);
debug_assert_eq!(data.local_expn_hashes[self].0, Fingerprint::ZERO);
data.local_expn_hashes[self] = expn_hash;
let _old_id = data.expn_hash_to_expn_id.insert(expn_hash, self.to_expn_id());
debug_assert!(_old_id.is_none());
});
}
#[inline]
pub fn is_descendant_of(self, ancestor: LocalExpnId) -> bool {
self.to_expn_id().is_descendant_of(ancestor.to_expn_id())
}
/// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
/// `expn_id.is_descendant_of(ctxt.outer_expn())`.
#[inline]
pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
self.to_expn_id().outer_expn_is_descendant_of(ctxt)
}
/// Returns span for the macro which originally caused this expansion to happen.
///
/// Stops backtracing at include! boundary.
#[inline]
pub fn expansion_cause(self) -> Option<Span> {
self.to_expn_id().expansion_cause()
}
#[inline]
#[track_caller]
pub fn parent(self) -> LocalExpnId {
self.expn_data().parent.as_local().unwrap()
}
}
impl ExpnId {
/// The ID of the theoretical expansion that generates freshly parsed, unexpanded AST.
/// Invariant: we do not create any ExpnId with local_id == 0 and krate != 0.
pub const fn root() -> ExpnId {
ExpnId { krate: LOCAL_CRATE, local_id: ExpnIndex::from_u32(0) }
}
#[inline]
pub fn expn_hash(self) -> ExpnHash {
HygieneData::with(|data| data.expn_hash(self))
}
#[inline]
pub fn from_hash(hash: ExpnHash) -> Option<ExpnId> {
HygieneData::with(|data| data.expn_hash_to_expn_id.get(&hash).copied())
}
#[inline]
pub fn as_local(self) -> Option<LocalExpnId> {
if self.krate == LOCAL_CRATE { Some(LocalExpnId::from_raw(self.local_id)) } else { None }
}
#[inline]
#[track_caller]
pub fn expect_local(self) -> LocalExpnId {
self.as_local().unwrap()
}
#[inline]
pub fn expn_data(self) -> ExpnData {
HygieneData::with(|data| data.expn_data(self).clone())
}
#[inline]
pub fn is_descendant_of(self, ancestor: ExpnId) -> bool {
// a few "fast path" cases to avoid locking HygieneData
if ancestor == ExpnId::root() || ancestor == self {
return true;
}
if ancestor.krate != self.krate {
return false;
}
HygieneData::with(|data| data.is_descendant_of(self, ancestor))
}
/// `expn_id.outer_expn_is_descendant_of(ctxt)` is equivalent to but faster than
/// `expn_id.is_descendant_of(ctxt.outer_expn())`.
pub fn outer_expn_is_descendant_of(self, ctxt: SyntaxContext) -> bool {
HygieneData::with(|data| data.is_descendant_of(self, data.outer_expn(ctxt)))
}
/// Returns span for the macro which originally caused this expansion to happen.
///
/// Stops backtracing at include! boundary.
pub fn expansion_cause(mut self) -> Option<Span> {
let mut last_macro = None;
loop {
let expn_data = self.expn_data();
// Stop going up the backtrace once include! is encountered
if expn_data.is_root()
|| expn_data.kind == ExpnKind::Macro(MacroKind::Bang, sym::include)
{
break;
}
self = expn_data.call_site.ctxt().outer_expn();
last_macro = Some(expn_data.call_site);
}
last_macro
}
}
#[derive(Debug)]
pub struct HygieneData {
/// Each expansion should have an associated expansion data, but sometimes there's a delay
/// between creation of an expansion ID and obtaining its data (e.g. macros are collected
/// first and then resolved later), so we use an `Option` here.
local_expn_data: IndexVec<LocalExpnId, Option<ExpnData>>,
local_expn_hashes: IndexVec<LocalExpnId, ExpnHash>,
/// Data and hash information from external crates. We may eventually want to remove these
/// maps, and fetch the information directly from the other crate's metadata like DefIds do.
foreign_expn_data: FxHashMap<ExpnId, ExpnData>,
foreign_expn_hashes: FxHashMap<ExpnId, ExpnHash>,
expn_hash_to_expn_id: UnhashMap<ExpnHash, ExpnId>,
syntax_context_data: Vec<SyntaxContextData>,
syntax_context_map: FxHashMap<(SyntaxContext, ExpnId, Transparency), SyntaxContext>,
/// Maps the `local_hash` of an `ExpnData` to the next disambiguator value.
/// This is used by `update_disambiguator` to keep track of which `ExpnData`s
/// would have collisions without a disambiguator.
/// The keys of this map are always computed with `ExpnData.disambiguator`
/// set to 0.
expn_data_disambiguators: FxHashMap<Hash64, u32>,
}
impl HygieneData {
pub(crate) fn new(edition: Edition) -> Self {
let root_data = ExpnData::default(
ExpnKind::Root,
DUMMY_SP,
edition,
Some(CRATE_DEF_ID.to_def_id()),
None,
);
HygieneData {
local_expn_data: IndexVec::from_elem_n(Some(root_data), 1),
local_expn_hashes: IndexVec::from_elem_n(ExpnHash(Fingerprint::ZERO), 1),
foreign_expn_data: FxHashMap::default(),
foreign_expn_hashes: FxHashMap::default(),
expn_hash_to_expn_id: std::iter::once((ExpnHash(Fingerprint::ZERO), ExpnId::root()))
.collect(),
syntax_context_data: vec![SyntaxContextData {
outer_expn: ExpnId::root(),
outer_transparency: Transparency::Opaque,
parent: SyntaxContext(0),
opaque: SyntaxContext(0),
opaque_and_semitransparent: SyntaxContext(0),
dollar_crate_name: kw::DollarCrate,
}],
syntax_context_map: FxHashMap::default(),
expn_data_disambiguators: FxHashMap::default(),
}
}
pub fn with<T, F: FnOnce(&mut HygieneData) -> T>(f: F) -> T {
with_session_globals(|session_globals| f(&mut session_globals.hygiene_data.borrow_mut()))
}
#[inline]
fn local_expn_hash(&self, expn_id: LocalExpnId) -> ExpnHash {
self.local_expn_hashes[expn_id]
}
#[inline]
fn expn_hash(&self, expn_id: ExpnId) -> ExpnHash {
match expn_id.as_local() {
Some(expn_id) => self.local_expn_hashes[expn_id],
None => self.foreign_expn_hashes[&expn_id],
}
}
fn local_expn_data(&self, expn_id: LocalExpnId) -> &ExpnData {
self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
}
fn expn_data(&self, expn_id: ExpnId) -> &ExpnData {
if let Some(expn_id) = expn_id.as_local() {
self.local_expn_data[expn_id].as_ref().expect("no expansion data for an expansion ID")
} else {
&self.foreign_expn_data[&expn_id]
}
}
fn is_descendant_of(&self, mut expn_id: ExpnId, ancestor: ExpnId) -> bool {
// a couple "fast path" cases to avoid traversing parents in the loop below
if ancestor == ExpnId::root() {
return true;
}
if expn_id.krate != ancestor.krate {
return false;
}
loop {
if expn_id == ancestor {
return true;
}
if expn_id == ExpnId::root() {
return false;
}
expn_id = self.expn_data(expn_id).parent;
}
}
fn normalize_to_macros_2_0(&self, ctxt: SyntaxContext) -> SyntaxContext {
self.syntax_context_data[ctxt.0 as usize].opaque
}
fn normalize_to_macro_rules(&self, ctxt: SyntaxContext) -> SyntaxContext {
self.syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent
}
fn outer_expn(&self, ctxt: SyntaxContext) -> ExpnId {
self.syntax_context_data[ctxt.0 as usize].outer_expn
}
fn outer_mark(&self, ctxt: SyntaxContext) -> (ExpnId, Transparency) {
let data = &self.syntax_context_data[ctxt.0 as usize];
(data.outer_expn, data.outer_transparency)
}
fn parent_ctxt(&self, ctxt: SyntaxContext) -> SyntaxContext {
self.syntax_context_data[ctxt.0 as usize].parent
}
fn remove_mark(&self, ctxt: &mut SyntaxContext) -> (ExpnId, Transparency) {
let outer_mark = self.outer_mark(*ctxt);
*ctxt = self.parent_ctxt(*ctxt);
outer_mark
}
fn marks(&self, mut ctxt: SyntaxContext) -> Vec<(ExpnId, Transparency)> {
let mut marks = Vec::new();
while ctxt != SyntaxContext::root() {
debug!("marks: getting parent of {:?}", ctxt);
marks.push(self.outer_mark(ctxt));
ctxt = self.parent_ctxt(ctxt);
}
marks.reverse();
marks
}
fn walk_chain(&self, mut span: Span, to: SyntaxContext) -> Span {
debug!("walk_chain({:?}, {:?})", span, to);
debug!("walk_chain: span ctxt = {:?}", span.ctxt());
while span.from_expansion() && span.ctxt() != to {
let outer_expn = self.outer_expn(span.ctxt());
debug!("walk_chain({:?}): outer_expn={:?}", span, outer_expn);
let expn_data = self.expn_data(outer_expn);
debug!("walk_chain({:?}): expn_data={:?}", span, expn_data);
span = expn_data.call_site;
}
span
}
fn adjust(&self, ctxt: &mut SyntaxContext, expn_id: ExpnId) -> Option<ExpnId> {
let mut scope = None;
while !self.is_descendant_of(expn_id, self.outer_expn(*ctxt)) {
scope = Some(self.remove_mark(ctxt).0);
}
scope
}
fn apply_mark(
&mut self,
ctxt: SyntaxContext,
expn_id: ExpnId,
transparency: Transparency,
) -> SyntaxContext {
assert_ne!(expn_id, ExpnId::root());
if transparency == Transparency::Opaque {
return self.apply_mark_internal(ctxt, expn_id, transparency);
}
let call_site_ctxt = self.expn_data(expn_id).call_site.ctxt();
let mut call_site_ctxt = if transparency == Transparency::SemiTransparent {
self.normalize_to_macros_2_0(call_site_ctxt)
} else {
self.normalize_to_macro_rules(call_site_ctxt)
};
if call_site_ctxt.is_root() {
return self.apply_mark_internal(ctxt, expn_id, transparency);
}
// Otherwise, `expn_id` is a macros 1.0 definition and the call site is in a
// macros 2.0 expansion, i.e., a macros 1.0 invocation is in a macros 2.0 definition.
//
// In this case, the tokens from the macros 1.0 definition inherit the hygiene
// at their invocation. That is, we pretend that the macros 1.0 definition
// was defined at its invocation (i.e., inside the macros 2.0 definition)
// so that the macros 2.0 definition remains hygienic.
//
// See the example at `test/ui/hygiene/legacy_interaction.rs`.
for (expn_id, transparency) in self.marks(ctxt) {
call_site_ctxt = self.apply_mark_internal(call_site_ctxt, expn_id, transparency);
}
self.apply_mark_internal(call_site_ctxt, expn_id, transparency)
}
fn apply_mark_internal(
&mut self,
ctxt: SyntaxContext,
expn_id: ExpnId,
transparency: Transparency,
) -> SyntaxContext {
let syntax_context_data = &mut self.syntax_context_data;
let mut opaque = syntax_context_data[ctxt.0 as usize].opaque;
let mut opaque_and_semitransparent =
syntax_context_data[ctxt.0 as usize].opaque_and_semitransparent;
if transparency >= Transparency::Opaque {
let parent = opaque;
opaque = *self
.syntax_context_map
.entry((parent, expn_id, transparency))
.or_insert_with(|| {
let new_opaque = SyntaxContext(syntax_context_data.len() as u32);
syntax_context_data.push(SyntaxContextData {
outer_expn: expn_id,
outer_transparency: transparency,
parent,
opaque: new_opaque,
opaque_and_semitransparent: new_opaque,
dollar_crate_name: kw::DollarCrate,
});
new_opaque
});
}
if transparency >= Transparency::SemiTransparent {
let parent = opaque_and_semitransparent;
opaque_and_semitransparent = *self
.syntax_context_map
.entry((parent, expn_id, transparency))
.or_insert_with(|| {
let new_opaque_and_semitransparent =
SyntaxContext(syntax_context_data.len() as u32);
syntax_context_data.push(SyntaxContextData {
outer_expn: expn_id,
outer_transparency: transparency,
parent,
opaque,
opaque_and_semitransparent: new_opaque_and_semitransparent,
dollar_crate_name: kw::DollarCrate,
});
new_opaque_and_semitransparent
});
}
let parent = ctxt;
*self.syntax_context_map.entry((parent, expn_id, transparency)).or_insert_with(|| {
let new_opaque_and_semitransparent_and_transparent =
SyntaxContext(syntax_context_data.len() as u32);
syntax_context_data.push(SyntaxContextData {
outer_expn: expn_id,
outer_transparency: transparency,
parent,
opaque,
opaque_and_semitransparent,
dollar_crate_name: kw::DollarCrate,
});
new_opaque_and_semitransparent_and_transparent
})
}
}
pub fn clear_syntax_context_map() {
HygieneData::with(|data| data.syntax_context_map = FxHashMap::default());
}
pub fn walk_chain(span: Span, to: SyntaxContext) -> Span {
HygieneData::with(|data| data.walk_chain(span, to))
}
pub fn update_dollar_crate_names(mut get_name: impl FnMut(SyntaxContext) -> Symbol) {
// The new contexts that need updating are at the end of the list and have `$crate` as a name.
let (len, to_update) = HygieneData::with(|data| {
(
data.syntax_context_data.len(),
data.syntax_context_data
.iter()
.rev()
.take_while(|scdata| scdata.dollar_crate_name == kw::DollarCrate)
.count(),
)
});
// The callback must be called from outside of the `HygieneData` lock,
// since it will try to acquire it too.
let range_to_update = len - to_update..len;
let names: Vec<_> =
range_to_update.clone().map(|idx| get_name(SyntaxContext::from_u32(idx as u32))).collect();
HygieneData::with(|data| {
range_to_update.zip(names).for_each(|(idx, name)| {
data.syntax_context_data[idx].dollar_crate_name = name;
})
})
}
pub fn debug_hygiene_data(verbose: bool) -> String {
HygieneData::with(|data| {
if verbose {
format!("{data:#?}")
} else {
let mut s = String::from("Expansions:");
let mut debug_expn_data = |(id, expn_data): (&ExpnId, &ExpnData)| {
s.push_str(&format!(
"\n{:?}: parent: {:?}, call_site_ctxt: {:?}, def_site_ctxt: {:?}, kind: {:?}",
id,
expn_data.parent,
expn_data.call_site.ctxt(),
expn_data.def_site.ctxt(),
expn_data.kind,
))
};
data.local_expn_data.iter_enumerated().for_each(|(id, expn_data)| {
let expn_data = expn_data.as_ref().expect("no expansion data for an expansion ID");
debug_expn_data((&id.to_expn_id(), expn_data))
});
// Sort the hash map for more reproducible output.
// Because of this, it is fine to rely on the unstable iteration order of the map.
#[allow(rustc::potential_query_instability)]
let mut foreign_expn_data: Vec<_> = data.foreign_expn_data.iter().collect();
foreign_expn_data.sort_by_key(|(id, _)| (id.krate, id.local_id));
foreign_expn_data.into_iter().for_each(debug_expn_data);
s.push_str("\n\nSyntaxContexts:");
data.syntax_context_data.iter().enumerate().for_each(|(id, ctxt)| {
s.push_str(&format!(
"\n#{}: parent: {:?}, outer_mark: ({:?}, {:?})",
id, ctxt.parent, ctxt.outer_expn, ctxt.outer_transparency,
));
});
s
}
})
}
impl SyntaxContext {
#[inline]
pub const fn root() -> Self {
SyntaxContext(0)
}
#[inline]
pub const fn is_root(self) -> bool {
self.0 == SyntaxContext::root().as_u32()
}
#[inline]
pub(crate) const fn as_u32(self) -> u32 {
self.0
}
#[inline]
pub(crate) const fn from_u32(raw: u32) -> SyntaxContext {
SyntaxContext(raw)
}
/// Extend a syntax context with a given expansion and transparency.
pub(crate) fn apply_mark(self, expn_id: ExpnId, transparency: Transparency) -> SyntaxContext {
HygieneData::with(|data| data.apply_mark(self, expn_id, transparency))
}
/// Pulls a single mark off of the syntax context. This effectively moves the
/// context up one macro definition level. That is, if we have a nested macro
/// definition as follows:
///
/// ```ignore (illustrative)
/// macro_rules! f {
/// macro_rules! g {
/// ...
/// }
/// }
/// ```
///
/// and we have a SyntaxContext that is referring to something declared by an invocation
/// of g (call it g1), calling remove_mark will result in the SyntaxContext for the
/// invocation of f that created g1.
/// Returns the mark that was removed.
pub fn remove_mark(&mut self) -> ExpnId {
HygieneData::with(|data| data.remove_mark(self).0)
}
pub fn marks(self) -> Vec<(ExpnId, Transparency)> {
HygieneData::with(|data| data.marks(self))
}
/// Adjust this context for resolution in a scope created by the given expansion.
/// For example, consider the following three resolutions of `f`:
///
/// ```rust
/// #![feature(decl_macro)]
/// mod foo { pub fn f() {} } // `f`'s `SyntaxContext` is empty.
/// m!(f);
/// macro m($f:ident) {
/// mod bar {
/// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
/// pub fn $f() {} // `$f`'s `SyntaxContext` is empty.
/// }
/// foo::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
/// //^ Since `mod foo` is outside this expansion, `adjust` removes the mark from `f`,
/// //| and it resolves to `::foo::f`.
/// bar::f(); // `f`'s `SyntaxContext` has a single `ExpnId` from `m`
/// //^ Since `mod bar` not outside this expansion, `adjust` does not change `f`,
/// //| and it resolves to `::bar::f`.
/// bar::$f(); // `f`'s `SyntaxContext` is empty.
/// //^ Since `mod bar` is not outside this expansion, `adjust` does not change `$f`,
/// //| and it resolves to `::bar::$f`.
/// }
/// ```
/// This returns the expansion whose definition scope we use to privacy check the resolution,
/// or `None` if we privacy check as usual (i.e., not w.r.t. a macro definition scope).
pub fn adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
HygieneData::with(|data| data.adjust(self, expn_id))
}
/// Like `SyntaxContext::adjust`, but also normalizes `self` to macros 2.0.
pub fn normalize_to_macros_2_0_and_adjust(&mut self, expn_id: ExpnId) -> Option<ExpnId> {
HygieneData::with(|data| {
*self = data.normalize_to_macros_2_0(*self);
data.adjust(self, expn_id)
})
}
/// Adjust this context for resolution in a scope created by the given expansion
/// via a glob import with the given `SyntaxContext`.
/// For example:
///
/// ```compile_fail,E0425
/// #![feature(decl_macro)]
/// m!(f);
/// macro m($i:ident) {
/// mod foo {
/// pub fn f() {} // `f`'s `SyntaxContext` has a single `ExpnId` from `m`.
/// pub fn $i() {} // `$i`'s `SyntaxContext` is empty.
/// }
/// n!(f);
/// macro n($j:ident) {
/// use foo::*;
/// f(); // `f`'s `SyntaxContext` has a mark from `m` and a mark from `n`
/// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::f`.
/// $i(); // `$i`'s `SyntaxContext` has a mark from `n`
/// //^ `glob_adjust` removes the mark from `n`, so this resolves to `foo::$i`.
/// $j(); // `$j`'s `SyntaxContext` has a mark from `m`
/// //^ This cannot be glob-adjusted, so this is a resolution error.
/// }
/// }
/// ```
/// This returns `None` if the context cannot be glob-adjusted.
/// Otherwise, it returns the scope to use when privacy checking (see `adjust` for details).
pub fn glob_adjust(&mut self, expn_id: ExpnId, glob_span: Span) -> Option<Option<ExpnId>> {
HygieneData::with(|data| {
let mut scope = None;
let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
scope = Some(data.remove_mark(&mut glob_ctxt).0);
if data.remove_mark(self).0 != scope.unwrap() {
return None;
}
}
if data.adjust(self, expn_id).is_some() {
return None;
}
Some(scope)
})
}
/// Undo `glob_adjust` if possible:
///
/// ```ignore (illustrative)
/// if let Some(privacy_checking_scope) = self.reverse_glob_adjust(expansion, glob_ctxt) {
/// assert!(self.glob_adjust(expansion, glob_ctxt) == Some(privacy_checking_scope));
/// }
/// ```
pub fn reverse_glob_adjust(
&mut self,
expn_id: ExpnId,
glob_span: Span,
) -> Option<Option<ExpnId>> {
HygieneData::with(|data| {
if data.adjust(self, expn_id).is_some() {
return None;
}
let mut glob_ctxt = data.normalize_to_macros_2_0(glob_span.ctxt());
let mut marks = Vec::new();
while !data.is_descendant_of(expn_id, data.outer_expn(glob_ctxt)) {
marks.push(data.remove_mark(&mut glob_ctxt));
}
let scope = marks.last().map(|mark| mark.0);
while let Some((expn_id, transparency)) = marks.pop() {
*self = data.apply_mark(*self, expn_id, transparency);
}
Some(scope)
})
}
pub fn hygienic_eq(self, other: SyntaxContext, expn_id: ExpnId) -> bool {
HygieneData::with(|data| {
let mut self_normalized = data.normalize_to_macros_2_0(self);
data.adjust(&mut self_normalized, expn_id);
self_normalized == data.normalize_to_macros_2_0(other)
})
}
#[inline]
pub fn normalize_to_macros_2_0(self) -> SyntaxContext {
HygieneData::with(|data| data.normalize_to_macros_2_0(self))
}
#[inline]
pub fn normalize_to_macro_rules(self) -> SyntaxContext {
HygieneData::with(|data| data.normalize_to_macro_rules(self))
}
#[inline]
pub fn outer_expn(self) -> ExpnId {
HygieneData::with(|data| data.outer_expn(self))
}
/// `ctxt.outer_expn_data()` is equivalent to but faster than
/// `ctxt.outer_expn().expn_data()`.
#[inline]
pub fn outer_expn_data(self) -> ExpnData {
HygieneData::with(|data| data.expn_data(data.outer_expn(self)).clone())
}
#[inline]
pub fn outer_mark(self) -> (ExpnId, Transparency) {
HygieneData::with(|data| data.outer_mark(self))
}
pub fn dollar_crate_name(self) -> Symbol {
HygieneData::with(|data| data.syntax_context_data[self.0 as usize].dollar_crate_name)
}
pub fn edition(self) -> Edition {
HygieneData::with(|data| data.expn_data(data.outer_expn(self)).edition)
}
}
impl fmt::Debug for SyntaxContext {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "#{}", self.0)
}
}
impl Span {
/// Creates a fresh expansion with given properties.
/// Expansions are normally created by macros, but in some cases expansions are created for
/// other compiler-generated code to set per-span properties like allowed unstable features.
/// The returned span belongs to the created expansion and has the new properties,
/// but its location is inherited from the current span.
pub fn fresh_expansion(self, expn_id: LocalExpnId) -> Span {
HygieneData::with(|data| {
self.with_ctxt(data.apply_mark(
self.ctxt(),
expn_id.to_expn_id(),
Transparency::Transparent,
))
})
}
/// Reuses the span but adds information like the kind of the desugaring and features that are
/// allowed inside this span.
pub fn mark_with_reason(
self,
allow_internal_unstable: Option<Lrc<[Symbol]>>,
reason: DesugaringKind,
edition: Edition,
ctx: impl HashStableContext,
) -> Span {
let expn_data = ExpnData {
allow_internal_unstable,
..ExpnData::default(ExpnKind::Desugaring(reason), self, edition, None, None)
};
let expn_id = LocalExpnId::fresh(expn_data, ctx);
self.fresh_expansion(expn_id)
}
}
/// A subset of properties from both macro definition and macro call available through global data.
/// Avoid using this if you have access to the original definition or call structures.
#[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
pub struct ExpnData {
// --- The part unique to each expansion.
/// The kind of this expansion - macro or compiler desugaring.
pub kind: ExpnKind,
/// The expansion that produced this expansion.
pub parent: ExpnId,
/// The location of the actual macro invocation or syntax sugar , e.g.
/// `let x = foo!();` or `if let Some(y) = x {}`
///
/// This may recursively refer to other macro invocations, e.g., if
/// `foo!()` invoked `bar!()` internally, and there was an
/// expression inside `bar!`; the call_site of the expression in
/// the expansion would point to the `bar!` invocation; that
/// call_site span would have its own ExpnData, with the call_site
/// pointing to the `foo!` invocation.
pub call_site: Span,
/// Used to force two `ExpnData`s to have different `Fingerprint`s.
/// Due to macro expansion, it's possible to end up with two `ExpnId`s
/// that have identical `ExpnData`s. This violates the contract of `HashStable`
/// - the two `ExpnId`s are not equal, but their `Fingerprint`s are equal
/// (since the numerical `ExpnId` value is not considered by the `HashStable`
/// implementation).
///
/// The `disambiguator` field is set by `update_disambiguator` when two distinct
/// `ExpnId`s would end up with the same `Fingerprint`. Since `ExpnData` includes
/// a `krate` field, this value only needs to be unique within a single crate.
disambiguator: u32,
// --- The part specific to the macro/desugaring definition.
// --- It may be reasonable to share this part between expansions with the same definition,
// --- but such sharing is known to bring some minor inconveniences without also bringing
// --- noticeable perf improvements (PR #62898).
/// The span of the macro definition (possibly dummy).
/// This span serves only informational purpose and is not used for resolution.
pub def_site: Span,
/// List of `#[unstable]`/feature-gated features that the macro is allowed to use
/// internally without forcing the whole crate to opt-in
/// to them.
pub allow_internal_unstable: Option<Lrc<[Symbol]>>,
/// Edition of the crate in which the macro is defined.
pub edition: Edition,
/// The `DefId` of the macro being invoked,
/// if this `ExpnData` corresponds to a macro invocation
pub macro_def_id: Option<DefId>,
/// The normal module (`mod`) in which the expanded macro was defined.
pub parent_module: Option<DefId>,
/// Suppresses the `unsafe_code` lint for code produced by this macro.
pub allow_internal_unsafe: bool,
/// Enables the macro helper hack (`ident!(...)` -> `$crate::ident!(...)`) for this macro.
pub local_inner_macros: bool,
/// Should debuginfo for the macro be collapsed to the outermost expansion site (in other
/// words, was the macro definition annotated with `#[collapse_debuginfo]`)?
pub collapse_debuginfo: bool,
}
impl !PartialEq for ExpnData {}
impl !Hash for ExpnData {}
impl ExpnData {
pub fn new(
kind: ExpnKind,
parent: ExpnId,
call_site: Span,
def_site: Span,
allow_internal_unstable: Option<Lrc<[Symbol]>>,
edition: Edition,
macro_def_id: Option<DefId>,
parent_module: Option<DefId>,
allow_internal_unsafe: bool,
local_inner_macros: bool,
collapse_debuginfo: bool,
) -> ExpnData {
ExpnData {
kind,
parent,
call_site,
def_site,
allow_internal_unstable,
edition,
macro_def_id,
parent_module,
disambiguator: 0,
allow_internal_unsafe,
local_inner_macros,
collapse_debuginfo,
}
}
/// Constructs expansion data with default properties.
pub fn default(
kind: ExpnKind,
call_site: Span,
edition: Edition,
macro_def_id: Option<DefId>,
parent_module: Option<DefId>,
) -> ExpnData {
ExpnData {
kind,
parent: ExpnId::root(),
call_site,
def_site: DUMMY_SP,
allow_internal_unstable: None,
edition,
macro_def_id,
parent_module,
disambiguator: 0,
allow_internal_unsafe: false,
local_inner_macros: false,
collapse_debuginfo: false,
}
}
pub fn allow_unstable(
kind: ExpnKind,
call_site: Span,
edition: Edition,
allow_internal_unstable: Lrc<[Symbol]>,
macro_def_id: Option<DefId>,
parent_module: Option<DefId>,
) -> ExpnData {
ExpnData {
allow_internal_unstable: Some(allow_internal_unstable),
..ExpnData::default(kind, call_site, edition, macro_def_id, parent_module)
}
}
#[inline]
pub fn is_root(&self) -> bool {
matches!(self.kind, ExpnKind::Root)
}
#[inline]
fn hash_expn(&self, ctx: &mut impl HashStableContext) -> Hash64 {
let mut hasher = StableHasher::new();
self.hash_stable(ctx, &mut hasher);
hasher.finish()
}
}
/// Expansion kind.
#[derive(Clone, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
pub enum ExpnKind {
/// No expansion, aka root expansion. Only `ExpnId::root()` has this kind.
Root,
/// Expansion produced by a macro.
Macro(MacroKind, Symbol),
/// Transform done by the compiler on the AST.
AstPass(AstPass),
/// Desugaring done by the compiler during HIR lowering.
Desugaring(DesugaringKind),
}
impl ExpnKind {
pub fn descr(&self) -> String {
match *self {
ExpnKind::Root => kw::PathRoot.to_string(),
ExpnKind::Macro(macro_kind, name) => match macro_kind {
MacroKind::Bang => format!("{name}!"),
MacroKind::Attr => format!("#[{name}]"),
MacroKind::Derive => format!("#[derive({name})]"),
},
ExpnKind::AstPass(kind) => kind.descr().to_string(),
ExpnKind::Desugaring(kind) => format!("desugaring of {}", kind.descr()),
}
}
}
/// The kind of macro invocation or definition.
#[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug)]
#[derive(HashStable_Generic)]
pub enum MacroKind {
/// A bang macro `foo!()`.
Bang,
/// An attribute macro `#[foo]`.
Attr,
/// A derive macro `#[derive(Foo)]`
Derive,
}
impl MacroKind {
pub fn descr(self) -> &'static str {
match self {
MacroKind::Bang => "macro",
MacroKind::Attr => "attribute macro",
MacroKind::Derive => "derive macro",
}
}
pub fn descr_expected(self) -> &'static str {
match self {
MacroKind::Attr => "attribute",
_ => self.descr(),
}
}
pub fn article(self) -> &'static str {
match self {
MacroKind::Attr => "an",
_ => "a",
}
}
}
/// The kind of AST transform.
#[derive(Clone, Copy, Debug, PartialEq, Encodable, Decodable, HashStable_Generic)]
pub enum AstPass {
StdImports,
TestHarness,
ProcMacroHarness,
}
impl AstPass {
pub fn descr(self) -> &'static str {
match self {
AstPass::StdImports => "standard library imports",
AstPass::TestHarness => "test harness",
AstPass::ProcMacroHarness => "proc macro harness",
}
}
}
/// The kind of compiler desugaring.
#[derive(Clone, Copy, PartialEq, Debug, Encodable, Decodable, HashStable_Generic)]
pub enum DesugaringKind {
/// We desugar `if c { i } else { e }` to `match $ExprKind::Use(c) { true => i, _ => e }`.
/// However, we do not want to blame `c` for unreachability but rather say that `i`
/// is unreachable. This desugaring kind allows us to avoid blaming `c`.
/// This also applies to `while` loops.
CondTemporary,
QuestionMark,
TryBlock,
YeetExpr,
/// Desugaring of an `impl Trait` in return type position
/// to an `type Foo = impl Trait;` and replacing the
/// `impl Trait` with `Foo`.
OpaqueTy,
Async,
Await,
ForLoop,
WhileLoop,
}
impl DesugaringKind {
/// The description wording should combine well with "desugaring of {}".
pub fn descr(self) -> &'static str {
match self {
DesugaringKind::CondTemporary => "`if` or `while` condition",
DesugaringKind::Async => "`async` block or function",
DesugaringKind::Await => "`await` expression",
DesugaringKind::QuestionMark => "operator `?`",
DesugaringKind::TryBlock => "`try` block",
DesugaringKind::YeetExpr => "`do yeet` expression",
DesugaringKind::OpaqueTy => "`impl Trait`",
DesugaringKind::ForLoop => "`for` loop",
DesugaringKind::WhileLoop => "`while` loop",
}
}
}
#[derive(Default)]
pub struct HygieneEncodeContext {
/// All `SyntaxContexts` for which we have written `SyntaxContextData` into crate metadata.
/// This is `None` after we finish encoding `SyntaxContexts`, to ensure
/// that we don't accidentally try to encode any more `SyntaxContexts`
serialized_ctxts: Lock<FxHashSet<SyntaxContext>>,
/// The `SyntaxContexts` that we have serialized (e.g. as a result of encoding `Spans`)
/// in the most recent 'round' of serializing. Serializing `SyntaxContextData`
/// may cause us to serialize more `SyntaxContext`s, so serialize in a loop
/// until we reach a fixed point.
latest_ctxts: Lock<FxHashSet<SyntaxContext>>,
serialized_expns: Lock<FxHashSet<ExpnId>>,
latest_expns: Lock<FxHashSet<ExpnId>>,
}
impl HygieneEncodeContext {
/// Record the fact that we need to serialize the corresponding `ExpnData`.
pub fn schedule_expn_data_for_encoding(&self, expn: ExpnId) {
if !self.serialized_expns.lock().contains(&expn) {
self.latest_expns.lock().insert(expn);
}
}
pub fn encode<T>(
&self,
encoder: &mut T,
mut encode_ctxt: impl FnMut(&mut T, u32, &SyntaxContextData),
mut encode_expn: impl FnMut(&mut T, ExpnId, &ExpnData, ExpnHash),
) {
// When we serialize a `SyntaxContextData`, we may end up serializing
// a `SyntaxContext` that we haven't seen before
while !self.latest_ctxts.lock().is_empty() || !self.latest_expns.lock().is_empty() {
debug!(
"encode_hygiene: Serializing a round of {:?} SyntaxContextData: {:?}",
self.latest_ctxts.lock().len(),
self.latest_ctxts
);
// Consume the current round of SyntaxContexts.
// Drop the lock() temporary early
let latest_ctxts = { std::mem::take(&mut *self.latest_ctxts.lock()) };
// It's fine to iterate over a HashMap, because the serialization
// of the table that we insert data into doesn't depend on insertion
// order
#[allow(rustc::potential_query_instability)]
for_all_ctxts_in(latest_ctxts.into_iter(), |index, ctxt, data| {
if self.serialized_ctxts.lock().insert(ctxt) {
encode_ctxt(encoder, index, data);
}
});
let latest_expns = { std::mem::take(&mut *self.latest_expns.lock()) };
// Same as above, this is fine as we are inserting into a order-independent hashset
#[allow(rustc::potential_query_instability)]
for_all_expns_in(latest_expns.into_iter(), |expn, data, hash| {
if self.serialized_expns.lock().insert(expn) {
encode_expn(encoder, expn, data, hash);
}
});
}
debug!("encode_hygiene: Done serializing SyntaxContextData");
}
}
#[derive(Default)]
/// Additional information used to assist in decoding hygiene data
struct HygieneDecodeContextInner {
// Maps serialized `SyntaxContext` ids to a `SyntaxContext` in the current
// global `HygieneData`. When we deserialize a `SyntaxContext`, we need to create
// a new id in the global `HygieneData`. This map tracks the ID we end up picking,
// so that multiple occurrences of the same serialized id are decoded to the same
// `SyntaxContext`. This only stores `SyntaxContext`s which are completly decoded.
remapped_ctxts: Vec<Option<SyntaxContext>>,
/// Maps serialized `SyntaxContext` ids that are currently being decoded to a `SyntaxContext`.
decoding: FxHashMap<u32, SyntaxContext>,
}
#[derive(Default)]
/// Additional information used to assist in decoding hygiene data
pub struct HygieneDecodeContext {
inner: Lock<HygieneDecodeContextInner>,
/// A set of serialized `SyntaxContext` ids that are currently being decoded on each thread.
local_in_progress: WorkerLocal<RefCell<FxHashMap<u32, ()>>>,
}
/// Register an expansion which has been decoded from the on-disk-cache for the local crate.
pub fn register_local_expn_id(data: ExpnData, hash: ExpnHash) -> ExpnId {
HygieneData::with(|hygiene_data| {
let expn_id = hygiene_data.local_expn_data.next_index();
hygiene_data.local_expn_data.push(Some(data));
let _eid = hygiene_data.local_expn_hashes.push(hash);
debug_assert_eq!(expn_id, _eid);
let expn_id = expn_id.to_expn_id();
let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
debug_assert!(_old_id.is_none());
expn_id
})
}
/// Register an expansion which has been decoded from the metadata of a foreign crate.
pub fn register_expn_id(
krate: CrateNum,
local_id: ExpnIndex,
data: ExpnData,
hash: ExpnHash,
) -> ExpnId {
debug_assert!(data.parent == ExpnId::root() || krate == data.parent.krate);
let expn_id = ExpnId { krate, local_id };
HygieneData::with(|hygiene_data| {
let _old_data = hygiene_data.foreign_expn_data.insert(expn_id, data);
debug_assert!(_old_data.is_none() || cfg!(parallel_compiler));
let _old_hash = hygiene_data.foreign_expn_hashes.insert(expn_id, hash);
debug_assert!(_old_hash.is_none() || _old_hash == Some(hash));
let _old_id = hygiene_data.expn_hash_to_expn_id.insert(hash, expn_id);
debug_assert!(_old_id.is_none() || _old_id == Some(expn_id));
});
expn_id
}
/// Decode an expansion from the metadata of a foreign crate.
pub fn decode_expn_id(
krate: CrateNum,
index: u32,
decode_data: impl FnOnce(ExpnId) -> (ExpnData, ExpnHash),
) -> ExpnId {
if index == 0 {
trace!("decode_expn_id: deserialized root");
return ExpnId::root();
}
let index = ExpnIndex::from_u32(index);
// This function is used to decode metadata, so it cannot decode information about LOCAL_CRATE.
debug_assert_ne!(krate, LOCAL_CRATE);
let expn_id = ExpnId { krate, local_id: index };
// Fast path if the expansion has already been decoded.
if HygieneData::with(|hygiene_data| hygiene_data.foreign_expn_data.contains_key(&expn_id)) {
return expn_id;
}
// Don't decode the data inside `HygieneData::with`, since we need to recursively decode
// other ExpnIds
let (expn_data, hash) = decode_data(expn_id);
register_expn_id(krate, index, expn_data, hash)
}
// Decodes `SyntaxContext`, using the provided `HygieneDecodeContext`
// to track which `SyntaxContext`s we have already decoded.
// The provided closure will be invoked to deserialize a `SyntaxContextData`
// if we haven't already seen the id of the `SyntaxContext` we are deserializing.
pub fn decode_syntax_context<D: Decoder, F: FnOnce(&mut D, u32) -> SyntaxContextData>(
d: &mut D,
context: &HygieneDecodeContext,
decode_data: F,
) -> SyntaxContext {
let raw_id: u32 = Decodable::decode(d);
if raw_id == 0 {
trace!("decode_syntax_context: deserialized root");
// The root is special
return SyntaxContext::root();
}
let ctxt = {
let mut inner = context.inner.lock();
if let Some(ctxt) = inner.remapped_ctxts.get(raw_id as usize).copied().flatten() {
// This has already beeen decoded.
return ctxt;
}
match inner.decoding.entry(raw_id) {
Entry::Occupied(ctxt_entry) => {
match context.local_in_progress.borrow_mut().entry(raw_id) {
Entry::Occupied(..) => {
// We're decoding this already on the current thread. Return here
// and let the function higher up the stack finish decoding to handle
// recursive cases.
return *ctxt_entry.get();
}
Entry::Vacant(entry) => {
entry.insert(());
// Some other thread is current decoding this. Race with it.
*ctxt_entry.get()
}
}
}
Entry::Vacant(entry) => {
// We are the first thread to start decoding. Mark the current thread as being progress.
context.local_in_progress.borrow_mut().insert(raw_id, ());
// Allocate and store SyntaxContext id *before* calling the decoder function,
// as the SyntaxContextData may reference itself.
let new_ctxt = HygieneData::with(|hygiene_data| {
let new_ctxt = SyntaxContext(hygiene_data.syntax_context_data.len() as u32);
// Push a dummy SyntaxContextData to ensure that nobody else can get the
// same ID as us. This will be overwritten after call `decode_Data`
hygiene_data.syntax_context_data.push(SyntaxContextData {
outer_expn: ExpnId::root(),
outer_transparency: Transparency::Transparent,
parent: SyntaxContext::root(),
opaque: SyntaxContext::root(),
opaque_and_semitransparent: SyntaxContext::root(),
dollar_crate_name: kw::Empty,
});
new_ctxt
});
entry.insert(new_ctxt);
new_ctxt
}
}
};
// Don't try to decode data while holding the lock, since we need to
// be able to recursively decode a SyntaxContext
let mut ctxt_data = decode_data(d, raw_id);
// Reset `dollar_crate_name` so that it will be updated by `update_dollar_crate_names`
// We don't care what the encoding crate set this to - we want to resolve it
// from the perspective of the current compilation session
ctxt_data.dollar_crate_name = kw::DollarCrate;
// Overwrite the dummy data with our decoded SyntaxContextData
HygieneData::with(|hygiene_data| {
let dummy = std::mem::replace(
&mut hygiene_data.syntax_context_data[ctxt.as_u32() as usize],
ctxt_data,
);
if cfg!(not(parallel_compiler)) {
// Make sure nothing weird happened while `decode_data` was running.
// We used `kw::Empty` for the dummy value and we expect nothing to be
// modifying the dummy entry.
// This does not hold for the parallel compiler as another thread may
// have inserted the fully decoded data.
assert_eq!(dummy.dollar_crate_name, kw::Empty);
}
});
// Mark the context as completed
context.local_in_progress.borrow_mut().remove(&raw_id);
let mut inner = context.inner.lock();
let new_len = raw_id as usize + 1;
if inner.remapped_ctxts.len() < new_len {
inner.remapped_ctxts.resize(new_len, None);
}
inner.remapped_ctxts[raw_id as usize] = Some(ctxt);
inner.decoding.remove(&raw_id);
ctxt
}
fn for_all_ctxts_in<F: FnMut(u32, SyntaxContext, &SyntaxContextData)>(
ctxts: impl Iterator<Item = SyntaxContext>,
mut f: F,
) {
let all_data: Vec<_> = HygieneData::with(|data| {
ctxts.map(|ctxt| (ctxt, data.syntax_context_data[ctxt.0 as usize].clone())).collect()
});
for (ctxt, data) in all_data.into_iter() {
f(ctxt.0, ctxt, &data);
}
}
fn for_all_expns_in(
expns: impl Iterator<Item = ExpnId>,
mut f: impl FnMut(ExpnId, &ExpnData, ExpnHash),
) {
let all_data: Vec<_> = HygieneData::with(|data| {
expns.map(|expn| (expn, data.expn_data(expn).clone(), data.expn_hash(expn))).collect()
});
for (expn, data, hash) in all_data.into_iter() {
f(expn, &data, hash);
}
}
impl<E: Encoder> Encodable<E> for LocalExpnId {
fn encode(&self, e: &mut E) {
self.to_expn_id().encode(e);
}
}
impl<E: Encoder> Encodable<E> for ExpnId {
default fn encode(&self, _: &mut E) {
panic!("cannot encode `ExpnId` with `{}`", std::any::type_name::<E>());
}
}
impl<D: Decoder> Decodable<D> for LocalExpnId {
fn decode(d: &mut D) -> Self {
ExpnId::expect_local(ExpnId::decode(d))
}
}
impl<D: Decoder> Decodable<D> for ExpnId {
default fn decode(_: &mut D) -> Self {
panic!("cannot decode `ExpnId` with `{}`", std::any::type_name::<D>());
}
}
pub fn raw_encode_syntax_context<E: Encoder>(
ctxt: SyntaxContext,
context: &HygieneEncodeContext,
e: &mut E,
) {
if !context.serialized_ctxts.lock().contains(&ctxt) {
context.latest_ctxts.lock().insert(ctxt);
}
ctxt.0.encode(e);
}
impl<E: Encoder> Encodable<E> for SyntaxContext {
default fn encode(&self, _: &mut E) {
panic!("cannot encode `SyntaxContext` with `{}`", std::any::type_name::<E>());
}
}
impl<D: Decoder> Decodable<D> for SyntaxContext {
default fn decode(_: &mut D) -> Self {
panic!("cannot decode `SyntaxContext` with `{}`", std::any::type_name::<D>());
}
}
/// Updates the `disambiguator` field of the corresponding `ExpnData`
/// such that the `Fingerprint` of the `ExpnData` does not collide with
/// any other `ExpnIds`.
///
/// This method is called only when an `ExpnData` is first associated
/// with an `ExpnId` (when the `ExpnId` is initially constructed, or via
/// `set_expn_data`). It is *not* called for foreign `ExpnId`s deserialized
/// from another crate's metadata - since `ExpnHash` includes the stable crate id,
/// collisions are only possible between `ExpnId`s within the same crate.
fn update_disambiguator(expn_data: &mut ExpnData, mut ctx: impl HashStableContext) -> ExpnHash {
// This disambiguator should not have been set yet.
assert_eq!(expn_data.disambiguator, 0, "Already set disambiguator for ExpnData: {expn_data:?}");
assert_default_hashing_controls(&ctx, "ExpnData (disambiguator)");
let mut expn_hash = expn_data.hash_expn(&mut ctx);
let disambiguator = HygieneData::with(|data| {
// If this is the first ExpnData with a given hash, then keep our
// disambiguator at 0 (the default u32 value)
let disambig = data.expn_data_disambiguators.entry(expn_hash).or_default();
let disambiguator = *disambig;
*disambig += 1;
disambiguator
});
if disambiguator != 0 {
debug!("Set disambiguator for expn_data={:?} expn_hash={:?}", expn_data, expn_hash);
expn_data.disambiguator = disambiguator;
expn_hash = expn_data.hash_expn(&mut ctx);
// Verify that the new disambiguator makes the hash unique
#[cfg(debug_assertions)]
HygieneData::with(|data| {
assert_eq!(
data.expn_data_disambiguators.get(&expn_hash),
None,
"Hash collision after disambiguator update!",
);
});
}
ExpnHash::new(ctx.def_path_hash(LOCAL_CRATE.as_def_id()).stable_crate_id(), expn_hash)
}
impl<CTX: HashStableContext> HashStable<CTX> for SyntaxContext {
fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
const TAG_EXPANSION: u8 = 0;
const TAG_NO_EXPANSION: u8 = 1;
if self.is_root() {
TAG_NO_EXPANSION.hash_stable(ctx, hasher);
} else {
TAG_EXPANSION.hash_stable(ctx, hasher);
let (expn_id, transparency) = self.outer_mark();
expn_id.hash_stable(ctx, hasher);
transparency.hash_stable(ctx, hasher);
}
}
}
impl<CTX: HashStableContext> HashStable<CTX> for ExpnId {
fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
assert_default_hashing_controls(ctx, "ExpnId");
let hash = if *self == ExpnId::root() {
// Avoid fetching TLS storage for a trivial often-used value.
Fingerprint::ZERO
} else {
self.expn_hash().0
};
hash.hash_stable(ctx, hasher);
}
}