1 //! An "interner" is a data structure that associates values with usize tags and
2 //! allows bidirectional lookup; i.e., given a value, one can easily find the
3 //! type, and vice versa.
5 use rustc_arena::DroplessArena;
6 use rustc_data_structures::fx::FxHashMap;
7 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
8 use rustc_macros::HashStable_Generic;
9 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
11 use std::cmp::{Ord, PartialEq, PartialOrd};
13 use std::hash::{Hash, Hasher};
16 use crate::{Span, DUMMY_SP, SESSION_GLOBALS};
21 // The proc macro code for this is in `src/librustc_macros/src/symbols.rs`.
23 // After modifying this list adjust `is_special`, `is_used_keyword`/`is_unused_keyword`,
24 // this should be rarely necessary though if the keywords are kept in alphabetic order.
26 // Special reserved identifiers used internally for elided lifetimes,
27 // unnamed method parameters, crate root module, error recovery etc.
30 DollarCrate: "$crate",
33 // Keywords that are used in stable Rust.
70 // Keywords that are used in unstable Rust or reserved for future use.
84 // Edition-specific keywords that are used in stable Rust.
85 Async: "async", // >= 2018 Edition only
86 Await: "await", // >= 2018 Edition only
87 Dyn: "dyn", // >= 2018 Edition only
89 // Edition-specific keywords that are used in unstable Rust or reserved for future use.
90 Try: "try", // >= 2018 Edition only
92 // Special lifetime names
93 UnderscoreLifetime: "'_",
94 StaticLifetime: "'static",
96 // Weak keywords, have special meaning only in specific contexts.
100 MacroRules: "macro_rules",
105 // Pre-interned symbols that can be referred to with `rustc_span::sym::*`.
107 // The symbol is the stringified identifier unless otherwise specified, in
108 // which case the name should mention the non-identifier punctuation.
109 // E.g. `sym::proc_dash_macro` represents "proc-macro", and it shouldn't be
110 // called `sym::proc_macro` because then it's easy to mistakenly think it
111 // represents "proc_macro".
113 // As well as the symbols listed, there are symbols for the strings
114 // "0", "1", ..., "9", which are accessible via `sym::integer`.
116 // The proc macro will abort if symbols are not in alphabetical order (as
117 // defined by `impl Ord for str`) or if any symbols are duplicated. Vim
118 // users can sort the list by selecting it and executing the command
119 // `:'<,'>!LC_ALL=C sort`.
121 // There is currently no checking that all symbols are used; that would be
179 ProceduralMasqueradeDummyType,
217 aarch64_target_feature,
222 abi_msp430_interrupt,
235 advanced_slice_patterns,
250 allow_internal_unsafe,
251 allow_internal_unstable,
252 allow_internal_unstable_backcompat_hack,
258 arbitrary_enum_discriminant,
259 arbitrary_self_types,
271 assert_receiver_is_total_eq,
275 associated_type_bounds,
276 associated_type_defaults,
287 augmented_assignments,
289 automatically_derived,
290 avx512_target_feature,
296 bind_by_move_pattern_guards,
307 borrowck_graphviz_format,
308 borrowck_graphviz_postflow,
309 borrowck_graphviz_preflow,
313 braced_empty_structs,
323 capture_disjoint_fields,
335 cfg_target_has_atomic,
336 cfg_target_thread_local,
346 closure_to_fn_coercion,
348 cmpxchg16b_target_feature,
349 cmse_nonsecure_entry,
357 conservative_impl_trait,
360 const_compare_raw_pointers,
363 const_evaluatable_checked,
366 const_fn_floating_point_arithmetic,
367 const_fn_fn_ptr_basics,
373 const_in_array_repeat_expressions,
379 const_precise_live_drops,
382 const_raw_ptr_to_usize_cast,
384 const_trait_bound_opt_out,
407 crate_visibility_modifier,
408 crt_dash_static: "crt-static",
417 custom_inner_attributes,
418 custom_test_frameworks,
432 default_alloc_error_handler,
433 default_lib_allocator,
434 default_type_parameter_fallback,
436 delay_span_bug_from_inside_query,
444 destructuring_assignment,
460 document_private_items,
461 dotdot_in_tuple_patterns,
462 dotdoteq_in_patterns,
467 dropck_parametricity,
474 emit_enum_variant_arg,
482 ermsb_target_feature,
487 exclusive_range_pattern,
488 exhaustive_integer_patterns,
499 extern_absolute_paths,
500 extern_crate_item_prelude,
522 field_init_shorthand,
527 float_to_int_unchecked,
553 from_size_align_unchecked,
566 generic_associated_types,
573 half_open_range_patterns,
575 hexagon_target_feature,
577 homogeneous_aggregate,
593 if_while_or_patterns,
595 impl_header_lifetime_elision,
598 impl_trait_in_bindings,
604 inclusive_range_syntax,
607 infer_outlives_requirements,
608 infer_static_outlives_requirements,
618 irrefutable_let_patterns,
622 issue_5723_bootstrap,
623 issue_tracker_base_url,
634 lazy_normalization_consts,
646 link_llvm_intrinsics,
664 macro_at_most_once_rep,
667 macro_lifetime_matcher,
668 macro_literal_matcher,
680 match_beginning_vert,
681 match_default_bindings,
707 movbe_target_feature,
757 nontrapping_dash_fptoint: "nontrapping-fptoint",
762 object_safe_for_dispatch,
765 omit_gdb_pretty_printer_section,
774 optin_builtin_traits,
783 overlapping_marker_traits,
791 panic_implementation,
818 post_dash_lto: "post-lto",
819 powerpc_target_feature,
824 pre_dash_lto: "pre-lto",
825 precise_pointer_size_matching,
829 prefetch_read_instruction,
831 prefetch_write_instruction,
836 proc_dash_macro: "proc-macro",
838 proc_macro_attribute,
844 proc_macro_internals,
846 proc_macro_non_items,
847 proc_macro_path_invoc,
856 quad_precision_float,
863 re_rebalance_coherence,
866 read_enum_variant_arg,
874 reexport_test_harness_main,
895 riscv_target_feature,
907 rust_eh_catch_typeinfo,
909 rust_eh_register_frames,
910 rust_eh_unregister_frames,
914 rustc_allocator_nounwind,
915 rustc_allow_const_fn_unstable,
916 rustc_args_required_const,
919 rustc_capture_analysis,
922 rustc_const_unstable,
923 rustc_conversion_suggestion,
926 rustc_diagnostic_item,
927 rustc_diagnostic_macros,
930 rustc_dump_env_program_clauses,
931 rustc_dump_program_clauses,
932 rustc_dump_user_substs,
934 rustc_expected_cgu_reuse,
935 rustc_if_this_changed,
936 rustc_inherit_overflow_checks,
938 rustc_layout_scalar_valid_range_end,
939 rustc_layout_scalar_valid_range_start,
940 rustc_macro_transparency,
942 rustc_nonnull_optimization_guaranteed,
943 rustc_object_lifetime_default,
944 rustc_on_unimplemented,
947 rustc_partition_codegened,
948 rustc_partition_reused,
950 rustc_peek_definite_init,
951 rustc_peek_indirectly_mutable,
953 rustc_peek_maybe_init,
954 rustc_peek_maybe_uninit,
955 rustc_polymorphize_error,
957 rustc_proc_macro_decls,
960 rustc_reservation_impl,
962 rustc_specialization_trait,
964 rustc_std_internal_symbol,
968 rustc_then_this_would_need,
969 rustc_unsafe_specialization_marker,
972 rvalue_static_promotion,
1020 simd_reduce_add_ordered,
1021 simd_reduce_add_unordered,
1026 simd_reduce_max_nanless,
1028 simd_reduce_min_nanless,
1029 simd_reduce_mul_ordered,
1030 simd_reduce_mul_unordered,
1034 simd_saturating_add,
1035 simd_saturating_sub,
1038 simd_select_bitmask,
1062 sse4a_target_feature,
1075 stmt_expr_attributes,
1076 stop_after_dataflow,
1081 struct_field_attributes,
1103 target_has_atomic_equal_alignment,
1104 target_has_atomic_load_store,
1106 target_pointer_width,
1107 target_target_vendor,
1108 target_thread_local,
1114 termination_trait_test,
1117 test_accepted_feature,
1119 test_removed_feature,
1144 type_alias_enum_variants,
1145 type_alias_impl_trait,
1156 unaligned_volatile_load,
1157 unaligned_volatile_store,
1166 underscore_const_names,
1168 underscore_lifetimes,
1171 universal_impl_trait,
1178 unrestricted_attribute_tokens,
1179 unsafe_block_in_unsafe_fn,
1181 unsafe_no_drop_flag,
1185 unsized_tuple_coercion,
1188 unused_qualifications,
1210 visible_private_types,
1212 volatile_copy_memory,
1213 volatile_copy_nonoverlapping_memory,
1215 volatile_set_memory,
1219 wasm_target_feature,
1231 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1239 /// Constructs a new identifier from a symbol and a span.
1240 pub const fn new(name: Symbol, span: Span) -> Ident {
1241 Ident { name, span }
1244 /// Constructs a new identifier with a dummy span.
1246 pub const fn with_dummy_span(name: Symbol) -> Ident {
1247 Ident::new(name, DUMMY_SP)
1251 pub fn invalid() -> Ident {
1252 Ident::with_dummy_span(kw::Invalid)
1255 /// Maps a string to an identifier with a dummy span.
1256 pub fn from_str(string: &str) -> Ident {
1257 Ident::with_dummy_span(Symbol::intern(string))
1260 /// Maps a string and a span to an identifier.
1261 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1262 Ident::new(Symbol::intern(string), span)
1265 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1266 pub fn with_span_pos(self, span: Span) -> Ident {
1267 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1270 pub fn without_first_quote(self) -> Ident {
1271 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1274 /// "Normalize" ident for use in comparisons using "item hygiene".
1275 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1276 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1277 /// different macro 2.0 macros.
1278 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1279 pub fn normalize_to_macros_2_0(self) -> Ident {
1280 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1283 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1284 /// Identifiers with same string value become same if they came from the same non-transparent
1285 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1286 /// non-transparent macros.
1287 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1288 pub fn normalize_to_macro_rules(self) -> Ident {
1289 Ident::new(self.name, self.span.normalize_to_macro_rules())
1292 /// Convert the name to a `SymbolStr`. This is a slowish operation because
1293 /// it requires locking the symbol interner.
1294 pub fn as_str(self) -> SymbolStr {
1299 impl PartialEq for Ident {
1300 fn eq(&self, rhs: &Self) -> bool {
1301 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
1305 impl Hash for Ident {
1306 fn hash<H: Hasher>(&self, state: &mut H) {
1307 self.name.hash(state);
1308 self.span.ctxt().hash(state);
1312 impl fmt::Debug for Ident {
1313 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1314 fmt::Display::fmt(self, f)?;
1315 fmt::Debug::fmt(&self.span.ctxt(), f)
1319 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1320 /// to printing the original identifier token written in source code (`token_to_string`),
1321 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1322 impl fmt::Display for Ident {
1323 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1324 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1328 /// This is the most general way to print identifiers.
1329 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1330 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1331 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1332 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1333 /// hygiene data, most importantly name of the crate it refers to.
1334 /// As a result we print `$crate` as `crate` if it refers to the local crate
1335 /// and as `::other_crate_name` if it refers to some other crate.
1336 /// Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
1337 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1338 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1339 /// done for a token stream or a single token.
1340 pub struct IdentPrinter {
1343 /// Span used for retrieving the crate name to which `$crate` refers to,
1344 /// if this field is `None` then the `$crate` conversion doesn't happen.
1345 convert_dollar_crate: Option<Span>,
1349 /// The most general `IdentPrinter` constructor. Do not use this.
1350 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1351 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1354 /// This implementation is supposed to be used when printing identifiers
1355 /// as a part of pretty-printing for larger AST pieces.
1356 /// Do not use this either.
1357 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1358 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1362 impl fmt::Display for IdentPrinter {
1363 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1366 } else if self.symbol == kw::DollarCrate {
1367 if let Some(span) = self.convert_dollar_crate {
1368 let converted = span.ctxt().dollar_crate_name();
1369 if !converted.is_path_segment_keyword() {
1372 return fmt::Display::fmt(&converted, f);
1375 fmt::Display::fmt(&self.symbol, f)
1379 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1381 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1382 // `ModernIdent` struct and use that as well.
1383 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1384 pub struct MacroRulesNormalizedIdent(Ident);
1386 impl MacroRulesNormalizedIdent {
1387 pub fn new(ident: Ident) -> Self {
1388 Self(ident.normalize_to_macro_rules())
1392 impl fmt::Debug for MacroRulesNormalizedIdent {
1393 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1394 fmt::Debug::fmt(&self.0, f)
1398 impl fmt::Display for MacroRulesNormalizedIdent {
1399 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1400 fmt::Display::fmt(&self.0, f)
1404 /// An interned string.
1406 /// Internally, a `Symbol` is implemented as an index, and all operations
1407 /// (including hashing, equality, and ordering) operate on that index. The use
1408 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1409 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1411 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1412 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1413 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1414 pub struct Symbol(SymbolIndex);
1416 rustc_index::newtype_index! {
1417 pub struct SymbolIndex { .. }
1421 const fn new(n: u32) -> Self {
1422 Symbol(SymbolIndex::from_u32(n))
1425 /// Maps a string to its interned representation.
1426 pub fn intern(string: &str) -> Self {
1427 with_interner(|interner| interner.intern(string))
1430 /// Access the symbol's chars. This is a slowish operation because it
1431 /// requires locking the symbol interner.
1432 pub fn with<F: FnOnce(&str) -> R, R>(self, f: F) -> R {
1433 with_interner(|interner| f(interner.get(self)))
1436 /// Convert to a `SymbolStr`. This is a slowish operation because it
1437 /// requires locking the symbol interner.
1438 pub fn as_str(self) -> SymbolStr {
1439 with_interner(|interner| unsafe {
1440 SymbolStr { string: std::mem::transmute::<&str, &str>(interner.get(self)) }
1444 pub fn as_u32(self) -> u32 {
1448 /// This method is supposed to be used in error messages, so it's expected to be
1449 /// identical to printing the original identifier token written in source code
1450 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1451 /// or edition, so we have to guess the rawness using the global edition.
1452 pub fn to_ident_string(self) -> String {
1453 Ident::with_dummy_span(self).to_string()
1457 impl fmt::Debug for Symbol {
1458 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1459 self.with(|str| fmt::Debug::fmt(&str, f))
1463 impl fmt::Display for Symbol {
1464 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1465 self.with(|str| fmt::Display::fmt(&str, f))
1469 impl<S: Encoder> Encodable<S> for Symbol {
1470 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
1471 self.with(|string| s.emit_str(string))
1475 impl<D: Decoder> Decodable<D> for Symbol {
1477 fn decode(d: &mut D) -> Result<Symbol, D::Error> {
1478 Ok(Symbol::intern(&d.read_str()?))
1482 impl<CTX> HashStable<CTX> for Symbol {
1484 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1485 self.as_str().hash_stable(hcx, hasher);
1489 impl<CTX> ToStableHashKey<CTX> for Symbol {
1490 type KeyType = SymbolStr;
1493 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {
1498 // The `&'static str`s in this type actually point into the arena.
1500 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1501 // found that to regress performance up to 2% in some cases. This might be
1502 // revisited after further improvements to `indexmap`.
1504 pub struct Interner {
1505 arena: DroplessArena,
1506 names: FxHashMap<&'static str, Symbol>,
1507 strings: Vec<&'static str>,
1511 fn prefill(init: &[&'static str]) -> Self {
1513 strings: init.into(),
1514 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1515 ..Default::default()
1520 pub fn intern(&mut self, string: &str) -> Symbol {
1521 if let Some(&name) = self.names.get(string) {
1525 let name = Symbol::new(self.strings.len() as u32);
1527 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
1530 unsafe { str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes())) };
1531 // It is safe to extend the arena allocation to `'static` because we only access
1532 // these while the arena is still alive.
1533 let string: &'static str = unsafe { &*(string as *const str) };
1534 self.strings.push(string);
1535 self.names.insert(string, name);
1539 // Get the symbol as a string. `Symbol::as_str()` should be used in
1540 // preference to this function.
1541 pub fn get(&self, symbol: Symbol) -> &str {
1542 self.strings[symbol.0.as_usize()]
1546 // This module has a very short name because it's used a lot.
1547 /// This module contains all the defined keyword `Symbol`s.
1549 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1550 /// For example `kw::Loop` or `kw::Break`.
1556 // This module has a very short name because it's used a lot.
1557 /// This module contains all the defined non-keyword `Symbol`s.
1559 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1560 /// For example `sym::rustfmt` or `sym::u8`.
1561 #[allow(rustc::default_hash_types)]
1564 use std::convert::TryInto;
1568 // Used from a macro in `librustc_feature/accepted.rs`
1569 pub use super::kw::MacroRules as macro_rules;
1571 // Get the symbol for an integer. The first few non-negative integers each
1572 // have a static symbol and therefore are fast.
1573 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1574 if let Result::Ok(idx) = n.try_into() {
1575 if let Option::Some(&sym_) = digits_array.get(idx) {
1579 Symbol::intern(&n.to_string())
1584 fn is_used_keyword_2018(self) -> bool {
1585 self >= kw::Async && self <= kw::Dyn
1588 fn is_unused_keyword_2018(self) -> bool {
1592 /// A keyword or reserved identifier that can be used as a path segment.
1593 pub fn is_path_segment_keyword(self) -> bool {
1595 || self == kw::SelfLower
1596 || self == kw::SelfUpper
1597 || self == kw::Crate
1598 || self == kw::PathRoot
1599 || self == kw::DollarCrate
1602 /// Returns `true` if the symbol is `true` or `false`.
1603 pub fn is_bool_lit(self) -> bool {
1604 self == kw::True || self == kw::False
1607 /// This symbol can be a raw identifier.
1608 pub fn can_be_raw(self) -> bool {
1609 self != kw::Invalid && self != kw::Underscore && !self.is_path_segment_keyword()
1614 // Returns `true` for reserved identifiers used internally for elided lifetimes,
1615 // unnamed method parameters, crate root module, error recovery etc.
1616 pub fn is_special(self) -> bool {
1617 self.name <= kw::Underscore
1620 /// Returns `true` if the token is a keyword used in the language.
1621 pub fn is_used_keyword(self) -> bool {
1622 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1623 self.name >= kw::As && self.name <= kw::While
1624 || self.name.is_used_keyword_2018() && self.span.rust_2018()
1627 /// Returns `true` if the token is a keyword reserved for possible future use.
1628 pub fn is_unused_keyword(self) -> bool {
1629 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1630 self.name >= kw::Abstract && self.name <= kw::Yield
1631 || self.name.is_unused_keyword_2018() && self.span.rust_2018()
1634 /// Returns `true` if the token is either a special identifier or a keyword.
1635 pub fn is_reserved(self) -> bool {
1636 self.is_special() || self.is_used_keyword() || self.is_unused_keyword()
1639 /// A keyword or reserved identifier that can be used as a path segment.
1640 pub fn is_path_segment_keyword(self) -> bool {
1641 self.name.is_path_segment_keyword()
1644 /// We see this identifier in a normal identifier position, like variable name or a type.
1645 /// How was it written originally? Did it use the raw form? Let's try to guess.
1646 pub fn is_raw_guess(self) -> bool {
1647 self.name.can_be_raw() && self.is_reserved()
1652 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1653 SESSION_GLOBALS.with(|session_globals| f(&mut *session_globals.symbol_interner.lock()))
1656 /// An alternative to `Symbol`, useful when the chars within the symbol need to
1657 /// be accessed. It deliberately has limited functionality and should only be
1658 /// used for temporary values.
1660 /// Because the interner outlives any thread which uses this type, we can
1661 /// safely treat `string` which points to interner data, as an immortal string,
1662 /// as long as this type never crosses between threads.
1664 // FIXME: ensure that the interner outlives any thread which uses `SymbolStr`,
1665 // by creating a new thread right after constructing the interner.
1666 #[derive(Clone, Eq, PartialOrd, Ord)]
1667 pub struct SymbolStr {
1668 string: &'static str,
1671 // This impl allows a `SymbolStr` to be directly equated with a `String` or
1673 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for SymbolStr {
1674 fn eq(&self, other: &T) -> bool {
1675 self.string == other.deref()
1679 impl !Send for SymbolStr {}
1680 impl !Sync for SymbolStr {}
1682 /// This impl means that if `ss` is a `SymbolStr`:
1683 /// - `*ss` is a `str`;
1684 /// - `&*ss` is a `&str` (and `match &*ss { ... }` is a common pattern).
1685 /// - `&ss as &str` is a `&str`, which means that `&ss` can be passed to a
1686 /// function expecting a `&str`.
1687 impl std::ops::Deref for SymbolStr {
1690 fn deref(&self) -> &str {
1695 impl fmt::Debug for SymbolStr {
1696 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1697 fmt::Debug::fmt(self.string, f)
1701 impl fmt::Display for SymbolStr {
1702 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1703 fmt::Display::fmt(self.string, f)
1707 impl<CTX> HashStable<CTX> for SymbolStr {
1709 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1710 self.string.hash_stable(hcx, hasher)
1714 impl<CTX> ToStableHashKey<CTX> for SymbolStr {
1715 type KeyType = SymbolStr;
1718 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {