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::{with_session_globals, Edition, Span, DUMMY_SP};
21 // The proc macro code for this is in `compiler/rustc_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
208 ProceduralMasqueradeDummyType,
249 aarch64_target_feature,
253 abi_c_cmse_nonsecure_call,
255 abi_msp430_interrupt,
268 advanced_slice_patterns,
283 allow_internal_unsafe,
284 allow_internal_unstable,
290 arbitrary_enum_discriminant,
291 arbitrary_self_types,
303 assert_receiver_is_total_eq,
307 associated_type_bounds,
308 associated_type_defaults,
319 augmented_assignments,
321 automatically_derived,
322 avx512_target_feature,
328 bind_by_move_pattern_guards,
339 borrowck_graphviz_format,
340 borrowck_graphviz_postflow,
341 borrowck_graphviz_preflow,
346 braced_empty_structs,
358 capture_disjoint_fields,
372 cfg_target_has_atomic,
373 cfg_target_thread_local,
383 closure_to_fn_coercion,
387 cmpxchg16b_target_feature,
388 cmse_nonsecure_entry,
396 conservative_impl_trait,
400 const_compare_raw_pointers,
403 const_evaluatable_checked,
406 const_fn_floating_point_arithmetic,
407 const_fn_fn_ptr_basics,
408 const_fn_trait_bound,
412 const_generic_defaults,
414 const_generics_defaults,
417 const_in_array_repeat_expressions,
423 const_precise_live_drops,
426 const_raw_ptr_to_usize_cast,
429 const_trait_bound_opt_out,
445 core_panic_2015_macro,
454 crate_visibility_modifier,
455 crt_dash_static: "crt-static",
464 custom_inner_attributes,
465 custom_test_frameworks,
479 default_alloc_error_handler,
480 default_lib_allocator,
481 default_method_body_is_const,
482 default_type_parameter_fallback,
484 delay_span_bug_from_inside_query,
493 destructuring_assignment,
511 document_private_items,
512 dotdot_in_tuple_patterns,
513 dotdoteq_in_patterns,
521 dropck_parametricity,
530 emit_enum_variant_arg,
538 ermsb_target_feature,
542 exclusive_range_pattern,
543 exhaustive_integer_patterns,
554 extended_key_value_attributes,
555 extern_absolute_paths,
556 extern_crate_item_prelude,
578 field_init_shorthand,
583 float_to_int_unchecked,
613 from_size_align_unchecked,
627 generic_associated_types,
634 half_open_range_patterns,
638 hexagon_target_feature,
640 homogeneous_aggregate,
657 if_while_or_patterns,
659 impl_header_lifetime_elision,
662 impl_trait_in_bindings,
669 inclusive_range_syntax,
672 infer_outlives_requirements,
673 infer_static_outlives_requirements,
674 inherent_associated_types,
685 irrefutable_let_patterns,
689 issue_5723_bootstrap,
690 issue_tracker_base_url,
704 lazy_normalization_consts,
717 link_llvm_intrinsics,
736 macro_at_most_once_rep,
737 macro_attributes_in_derive_output,
740 macro_lifetime_matcher,
741 macro_literal_matcher,
753 match_beginning_vert,
754 match_default_bindings,
780 min_type_alias_impl_trait,
789 more_qualified_paths,
791 movbe_target_feature,
803 native_link_modifiers,
804 native_link_modifiers_as_needed,
805 native_link_modifiers_bundle,
806 native_link_modifiers_verbatim,
807 native_link_modifiers_whole_archive,
855 object_safe_for_dispatch,
858 omit_gdb_pretty_printer_section,
867 optin_builtin_traits,
876 overlapping_marker_traits,
886 panic_implementation,
915 post_dash_lto: "post-lto",
916 powerpc_target_feature,
921 pre_dash_lto: "pre-lto",
922 precise_pointer_size_matching,
926 prefetch_read_instruction,
928 prefetch_write_instruction,
934 proc_dash_macro: "proc-macro",
936 proc_macro_attribute,
942 proc_macro_internals,
944 proc_macro_non_items,
945 proc_macro_path_invoc,
960 quad_precision_float,
968 re_rebalance_coherence,
971 read_enum_variant_arg,
979 reexport_test_harness_main,
980 ref_unwind_safe_trait,
994 relaxed_struct_unsize,
1011 riscv_target_feature,
1027 rust_eh_catch_typeinfo,
1028 rust_eh_personality,
1029 rust_eh_register_frames,
1030 rust_eh_unregister_frames,
1034 rustc_allocator_nounwind,
1035 rustc_allow_const_fn_unstable,
1037 rustc_builtin_macro,
1038 rustc_capture_analysis,
1041 rustc_const_unstable,
1042 rustc_conversion_suggestion,
1045 rustc_diagnostic_item,
1046 rustc_diagnostic_macros,
1049 rustc_dump_env_program_clauses,
1050 rustc_dump_program_clauses,
1051 rustc_dump_user_substs,
1054 rustc_evaluate_where_clauses,
1055 rustc_expected_cgu_reuse,
1056 rustc_if_this_changed,
1057 rustc_inherit_overflow_checks,
1058 rustc_insignificant_dtor,
1060 rustc_layout_scalar_valid_range_end,
1061 rustc_layout_scalar_valid_range_start,
1062 rustc_legacy_const_generics,
1063 rustc_macro_transparency,
1066 rustc_nonnull_optimization_guaranteed,
1067 rustc_object_lifetime_default,
1068 rustc_on_unimplemented,
1071 rustc_partition_codegened,
1072 rustc_partition_reused,
1074 rustc_peek_definite_init,
1075 rustc_peek_indirectly_mutable,
1076 rustc_peek_liveness,
1077 rustc_peek_maybe_init,
1078 rustc_peek_maybe_uninit,
1079 rustc_polymorphize_error,
1081 rustc_proc_macro_decls,
1084 rustc_reservation_impl,
1086 rustc_skip_array_during_method_dispatch,
1087 rustc_specialization_trait,
1089 rustc_std_internal_symbol,
1093 rustc_then_this_would_need,
1094 rustc_unsafe_specialization_marker,
1098 rvalue_static_promotion,
1148 simd_reduce_add_ordered,
1149 simd_reduce_add_unordered,
1154 simd_reduce_max_nanless,
1156 simd_reduce_min_nanless,
1157 simd_reduce_mul_ordered,
1158 simd_reduce_mul_unordered,
1163 simd_saturating_add,
1164 simd_saturating_sub,
1167 simd_select_bitmask,
1196 sse4a_target_feature,
1208 std_panic_2015_macro,
1211 stmt_expr_attributes,
1212 stop_after_dataflow,
1217 struct_field_attributes,
1240 target_has_atomic_equal_alignment,
1241 target_has_atomic_load_store,
1243 target_pointer_width,
1244 target_target_vendor,
1245 target_thread_local,
1251 termination_trait_test,
1254 test_accepted_feature,
1256 test_removed_feature,
1285 type_alias_enum_variants,
1286 type_alias_impl_trait,
1297 unaligned_volatile_load,
1298 unaligned_volatile_store,
1307 underscore_const_names,
1309 underscore_lifetimes,
1312 universal_impl_trait,
1320 unrestricted_attribute_tokens,
1321 unsafe_block_in_unsafe_fn,
1323 unsafe_no_drop_flag,
1327 unsized_tuple_coercion,
1330 unused_qualifications,
1354 visible_private_types,
1356 volatile_copy_memory,
1357 volatile_copy_nonoverlapping_memory,
1359 volatile_set_memory,
1366 wasm_target_feature,
1383 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1391 /// Constructs a new identifier from a symbol and a span.
1392 pub const fn new(name: Symbol, span: Span) -> Ident {
1393 Ident { name, span }
1396 /// Constructs a new identifier with a dummy span.
1398 pub const fn with_dummy_span(name: Symbol) -> Ident {
1399 Ident::new(name, DUMMY_SP)
1403 pub fn invalid() -> Ident {
1404 Ident::with_dummy_span(kw::Empty)
1407 /// Maps a string to an identifier with a dummy span.
1408 pub fn from_str(string: &str) -> Ident {
1409 Ident::with_dummy_span(Symbol::intern(string))
1412 /// Maps a string and a span to an identifier.
1413 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1414 Ident::new(Symbol::intern(string), span)
1417 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1418 pub fn with_span_pos(self, span: Span) -> Ident {
1419 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1422 pub fn without_first_quote(self) -> Ident {
1423 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1426 /// "Normalize" ident for use in comparisons using "item hygiene".
1427 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1428 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1429 /// different macro 2.0 macros.
1430 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1431 pub fn normalize_to_macros_2_0(self) -> Ident {
1432 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1435 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1436 /// Identifiers with same string value become same if they came from the same non-transparent
1437 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1438 /// non-transparent macros.
1439 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1440 pub fn normalize_to_macro_rules(self) -> Ident {
1441 Ident::new(self.name, self.span.normalize_to_macro_rules())
1444 /// Convert the name to a `SymbolStr`. This is a slowish operation because
1445 /// it requires locking the symbol interner.
1446 pub fn as_str(self) -> SymbolStr {
1451 impl PartialEq for Ident {
1452 fn eq(&self, rhs: &Self) -> bool {
1453 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
1457 impl Hash for Ident {
1458 fn hash<H: Hasher>(&self, state: &mut H) {
1459 self.name.hash(state);
1460 self.span.ctxt().hash(state);
1464 impl fmt::Debug for Ident {
1465 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1466 fmt::Display::fmt(self, f)?;
1467 fmt::Debug::fmt(&self.span.ctxt(), f)
1471 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1472 /// to printing the original identifier token written in source code (`token_to_string`),
1473 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1474 impl fmt::Display for Ident {
1475 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1476 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1480 /// This is the most general way to print identifiers.
1481 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1482 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1483 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1484 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1485 /// hygiene data, most importantly name of the crate it refers to.
1486 /// As a result we print `$crate` as `crate` if it refers to the local crate
1487 /// and as `::other_crate_name` if it refers to some other crate.
1488 /// Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
1489 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1490 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1491 /// done for a token stream or a single token.
1492 pub struct IdentPrinter {
1495 /// Span used for retrieving the crate name to which `$crate` refers to,
1496 /// if this field is `None` then the `$crate` conversion doesn't happen.
1497 convert_dollar_crate: Option<Span>,
1501 /// The most general `IdentPrinter` constructor. Do not use this.
1502 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1503 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1506 /// This implementation is supposed to be used when printing identifiers
1507 /// as a part of pretty-printing for larger AST pieces.
1508 /// Do not use this either.
1509 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1510 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1514 impl fmt::Display for IdentPrinter {
1515 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1518 } else if self.symbol == kw::DollarCrate {
1519 if let Some(span) = self.convert_dollar_crate {
1520 let converted = span.ctxt().dollar_crate_name();
1521 if !converted.is_path_segment_keyword() {
1524 return fmt::Display::fmt(&converted, f);
1527 fmt::Display::fmt(&self.symbol, f)
1531 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1533 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1534 // `ModernIdent` struct and use that as well.
1535 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1536 pub struct MacroRulesNormalizedIdent(Ident);
1538 impl MacroRulesNormalizedIdent {
1539 pub fn new(ident: Ident) -> Self {
1540 Self(ident.normalize_to_macro_rules())
1544 impl fmt::Debug for MacroRulesNormalizedIdent {
1545 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1546 fmt::Debug::fmt(&self.0, f)
1550 impl fmt::Display for MacroRulesNormalizedIdent {
1551 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1552 fmt::Display::fmt(&self.0, f)
1556 /// An interned string.
1558 /// Internally, a `Symbol` is implemented as an index, and all operations
1559 /// (including hashing, equality, and ordering) operate on that index. The use
1560 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1561 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1563 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1564 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1565 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1566 pub struct Symbol(SymbolIndex);
1568 rustc_index::newtype_index! {
1569 pub struct SymbolIndex { .. }
1573 const fn new(n: u32) -> Self {
1574 Symbol(SymbolIndex::from_u32(n))
1577 /// Maps a string to its interned representation.
1578 pub fn intern(string: &str) -> Self {
1579 with_interner(|interner| interner.intern(string))
1582 /// Convert to a `SymbolStr`. This is a slowish operation because it
1583 /// requires locking the symbol interner.
1584 pub fn as_str(self) -> SymbolStr {
1585 with_interner(|interner| unsafe {
1586 SymbolStr { string: std::mem::transmute::<&str, &str>(interner.get(self)) }
1590 pub fn as_u32(self) -> u32 {
1594 pub fn is_empty(self) -> bool {
1598 /// This method is supposed to be used in error messages, so it's expected to be
1599 /// identical to printing the original identifier token written in source code
1600 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1601 /// or edition, so we have to guess the rawness using the global edition.
1602 pub fn to_ident_string(self) -> String {
1603 Ident::with_dummy_span(self).to_string()
1607 impl fmt::Debug for Symbol {
1608 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1609 fmt::Debug::fmt(&self.as_str(), f)
1613 impl fmt::Display for Symbol {
1614 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1615 fmt::Display::fmt(&self.as_str(), f)
1619 impl<S: Encoder> Encodable<S> for Symbol {
1620 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
1621 s.emit_str(&self.as_str())
1625 impl<D: Decoder> Decodable<D> for Symbol {
1627 fn decode(d: &mut D) -> Result<Symbol, D::Error> {
1628 Ok(Symbol::intern(&d.read_str()?))
1632 impl<CTX> HashStable<CTX> for Symbol {
1634 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1635 self.as_str().hash_stable(hcx, hasher);
1639 impl<CTX> ToStableHashKey<CTX> for Symbol {
1640 type KeyType = SymbolStr;
1643 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {
1648 // The `&'static str`s in this type actually point into the arena.
1650 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1651 // found that to regress performance up to 2% in some cases. This might be
1652 // revisited after further improvements to `indexmap`.
1654 pub struct Interner {
1655 arena: DroplessArena,
1656 names: FxHashMap<&'static str, Symbol>,
1657 strings: Vec<&'static str>,
1661 fn prefill(init: &[&'static str]) -> Self {
1663 strings: init.into(),
1664 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1665 ..Default::default()
1670 pub fn intern(&mut self, string: &str) -> Symbol {
1671 if let Some(&name) = self.names.get(string) {
1675 let name = Symbol::new(self.strings.len() as u32);
1677 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
1680 unsafe { str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes())) };
1681 // It is safe to extend the arena allocation to `'static` because we only access
1682 // these while the arena is still alive.
1683 let string: &'static str = unsafe { &*(string as *const str) };
1684 self.strings.push(string);
1685 self.names.insert(string, name);
1689 // Get the symbol as a string. `Symbol::as_str()` should be used in
1690 // preference to this function.
1691 pub fn get(&self, symbol: Symbol) -> &str {
1692 self.strings[symbol.0.as_usize()]
1696 // This module has a very short name because it's used a lot.
1697 /// This module contains all the defined keyword `Symbol`s.
1699 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1700 /// For example `kw::Loop` or `kw::Break`.
1702 pub use super::kw_generated::*;
1705 // This module has a very short name because it's used a lot.
1706 /// This module contains all the defined non-keyword `Symbol`s.
1708 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1709 /// For example `sym::rustfmt` or `sym::u8`.
1712 use std::convert::TryInto;
1715 pub use super::sym_generated::*;
1717 // Used from a macro in `librustc_feature/accepted.rs`
1718 pub use super::kw::MacroRules as macro_rules;
1720 /// Get the symbol for an integer.
1722 /// The first few non-negative integers each have a static symbol and therefore
1724 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1725 if let Result::Ok(idx) = n.try_into() {
1727 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
1730 Symbol::intern(&n.to_string())
1735 fn is_special(self) -> bool {
1736 self <= kw::Underscore
1739 fn is_used_keyword_always(self) -> bool {
1740 self >= kw::As && self <= kw::While
1743 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1744 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
1747 fn is_unused_keyword_always(self) -> bool {
1748 self >= kw::Abstract && self <= kw::Yield
1751 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1752 self == kw::Try && edition() >= Edition::Edition2018
1755 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
1757 || self.is_used_keyword_always()
1758 || self.is_unused_keyword_always()
1759 || self.is_used_keyword_conditional(edition)
1760 || self.is_unused_keyword_conditional(edition)
1763 /// A keyword or reserved identifier that can be used as a path segment.
1764 pub fn is_path_segment_keyword(self) -> bool {
1766 || self == kw::SelfLower
1767 || self == kw::SelfUpper
1768 || self == kw::Crate
1769 || self == kw::PathRoot
1770 || self == kw::DollarCrate
1773 /// Returns `true` if the symbol is `true` or `false`.
1774 pub fn is_bool_lit(self) -> bool {
1775 self == kw::True || self == kw::False
1778 /// Returns `true` if this symbol can be a raw identifier.
1779 pub fn can_be_raw(self) -> bool {
1780 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
1785 // Returns `true` for reserved identifiers used internally for elided lifetimes,
1786 // unnamed method parameters, crate root module, error recovery etc.
1787 pub fn is_special(self) -> bool {
1788 self.name.is_special()
1791 /// Returns `true` if the token is a keyword used in the language.
1792 pub fn is_used_keyword(self) -> bool {
1793 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1794 self.name.is_used_keyword_always()
1795 || self.name.is_used_keyword_conditional(|| self.span.edition())
1798 /// Returns `true` if the token is a keyword reserved for possible future use.
1799 pub fn is_unused_keyword(self) -> bool {
1800 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1801 self.name.is_unused_keyword_always()
1802 || self.name.is_unused_keyword_conditional(|| self.span.edition())
1805 /// Returns `true` if the token is either a special identifier or a keyword.
1806 pub fn is_reserved(self) -> bool {
1807 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1808 self.name.is_reserved(|| self.span.edition())
1811 /// A keyword or reserved identifier that can be used as a path segment.
1812 pub fn is_path_segment_keyword(self) -> bool {
1813 self.name.is_path_segment_keyword()
1816 /// We see this identifier in a normal identifier position, like variable name or a type.
1817 /// How was it written originally? Did it use the raw form? Let's try to guess.
1818 pub fn is_raw_guess(self) -> bool {
1819 self.name.can_be_raw() && self.is_reserved()
1824 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1825 with_session_globals(|session_globals| f(&mut *session_globals.symbol_interner.lock()))
1828 /// An alternative to [`Symbol`], useful when the chars within the symbol need to
1829 /// be accessed. It deliberately has limited functionality and should only be
1830 /// used for temporary values.
1832 /// Because the interner outlives any thread which uses this type, we can
1833 /// safely treat `string` which points to interner data, as an immortal string,
1834 /// as long as this type never crosses between threads.
1836 // FIXME: ensure that the interner outlives any thread which uses `SymbolStr`,
1837 // by creating a new thread right after constructing the interner.
1838 #[derive(Clone, Eq, PartialOrd, Ord)]
1839 pub struct SymbolStr {
1840 string: &'static str,
1843 // This impl allows a `SymbolStr` to be directly equated with a `String` or
1845 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for SymbolStr {
1846 fn eq(&self, other: &T) -> bool {
1847 self.string == other.deref()
1851 impl !Send for SymbolStr {}
1852 impl !Sync for SymbolStr {}
1854 /// This impl means that if `ss` is a `SymbolStr`:
1855 /// - `*ss` is a `str`;
1856 /// - `&*ss` is a `&str` (and `match &*ss { ... }` is a common pattern).
1857 /// - `&ss as &str` is a `&str`, which means that `&ss` can be passed to a
1858 /// function expecting a `&str`.
1859 impl std::ops::Deref for SymbolStr {
1862 fn deref(&self) -> &str {
1867 impl fmt::Debug for SymbolStr {
1868 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1869 fmt::Debug::fmt(self.string, f)
1873 impl fmt::Display for SymbolStr {
1874 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1875 fmt::Display::fmt(self.string, f)
1879 impl<CTX> HashStable<CTX> for SymbolStr {
1881 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1882 self.string.hash_stable(hcx, hasher)
1886 impl<CTX> ToStableHashKey<CTX> for SymbolStr {
1887 type KeyType = SymbolStr;
1890 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {