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::{Edition, Span, DUMMY_SP, SESSION_GLOBALS};
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
194 ProceduralMasqueradeDummyType,
235 aarch64_target_feature,
239 abi_c_cmse_nonsecure_call,
241 abi_msp430_interrupt,
254 advanced_slice_patterns,
269 allow_internal_unsafe,
270 allow_internal_unstable,
276 arbitrary_enum_discriminant,
277 arbitrary_self_types,
289 assert_receiver_is_total_eq,
293 associated_type_bounds,
294 associated_type_defaults,
305 augmented_assignments,
307 automatically_derived,
308 avx512_target_feature,
314 bind_by_move_pattern_guards,
325 borrowck_graphviz_format,
326 borrowck_graphviz_postflow,
327 borrowck_graphviz_preflow,
332 braced_empty_structs,
344 capture_disjoint_fields,
357 cfg_target_has_atomic,
358 cfg_target_thread_local,
368 closure_to_fn_coercion,
370 cmpxchg16b_target_feature,
371 cmse_nonsecure_entry,
379 conservative_impl_trait,
383 const_compare_raw_pointers,
386 const_evaluatable_checked,
389 const_fn_floating_point_arithmetic,
390 const_fn_fn_ptr_basics,
391 const_fn_trait_bound,
395 const_generic_defaults,
397 const_generics_defaults,
400 const_in_array_repeat_expressions,
406 const_precise_live_drops,
409 const_raw_ptr_to_usize_cast,
412 const_trait_bound_opt_out,
429 core_panic_2015_macro,
438 crate_visibility_modifier,
439 crt_dash_static: "crt-static",
448 custom_inner_attributes,
449 custom_test_frameworks,
463 default_alloc_error_handler,
464 default_lib_allocator,
465 default_type_parameter_fallback,
467 delay_span_bug_from_inside_query,
475 destructuring_assignment,
492 document_private_items,
493 dotdot_in_tuple_patterns,
494 dotdoteq_in_patterns,
502 dropck_parametricity,
511 emit_enum_variant_arg,
519 ermsb_target_feature,
523 exclusive_range_pattern,
524 exhaustive_integer_patterns,
535 extended_key_value_attributes,
536 extern_absolute_paths,
537 extern_crate_item_prelude,
559 field_init_shorthand,
564 float_to_int_unchecked,
593 from_size_align_unchecked,
606 generic_associated_types,
613 half_open_range_patterns,
617 hexagon_target_feature,
619 homogeneous_aggregate,
636 if_while_or_patterns,
638 impl_header_lifetime_elision,
641 impl_trait_in_bindings,
648 inclusive_range_syntax,
651 infer_outlives_requirements,
652 infer_static_outlives_requirements,
653 inherent_associated_types,
664 irrefutable_let_patterns,
668 issue_5723_bootstrap,
669 issue_tracker_base_url,
682 lazy_normalization_consts,
694 link_llvm_intrinsics,
713 macro_at_most_once_rep,
714 macro_attributes_in_derive_output,
717 macro_lifetime_matcher,
718 macro_literal_matcher,
730 match_beginning_vert,
731 match_default_bindings,
751 min_type_alias_impl_trait,
759 more_qualified_paths,
761 movbe_target_feature,
773 native_link_modifiers,
774 native_link_modifiers_as_needed,
775 native_link_modifiers_bundle,
776 native_link_modifiers_verbatim,
777 native_link_modifiers_whole_archive,
825 object_safe_for_dispatch,
828 omit_gdb_pretty_printer_section,
837 optin_builtin_traits,
846 overlapping_marker_traits,
856 panic_implementation,
885 post_dash_lto: "post-lto",
886 powerpc_target_feature,
891 pre_dash_lto: "pre-lto",
892 precise_pointer_size_matching,
896 prefetch_read_instruction,
898 prefetch_write_instruction,
903 proc_dash_macro: "proc-macro",
905 proc_macro_attribute,
911 proc_macro_internals,
913 proc_macro_non_items,
914 proc_macro_path_invoc,
929 quad_precision_float,
936 re_rebalance_coherence,
939 read_enum_variant_arg,
947 reexport_test_harness_main,
962 relaxed_struct_unsize,
979 riscv_target_feature,
995 rust_eh_catch_typeinfo,
997 rust_eh_register_frames,
998 rust_eh_unregister_frames,
1002 rustc_allocator_nounwind,
1003 rustc_allow_const_fn_unstable,
1005 rustc_builtin_macro,
1006 rustc_capture_analysis,
1009 rustc_const_unstable,
1010 rustc_conversion_suggestion,
1013 rustc_diagnostic_item,
1014 rustc_diagnostic_macros,
1017 rustc_dump_env_program_clauses,
1018 rustc_dump_program_clauses,
1019 rustc_dump_user_substs,
1021 rustc_evaluate_where_clauses,
1022 rustc_expected_cgu_reuse,
1023 rustc_if_this_changed,
1024 rustc_inherit_overflow_checks,
1025 rustc_insignificant_dtor,
1027 rustc_layout_scalar_valid_range_end,
1028 rustc_layout_scalar_valid_range_start,
1029 rustc_legacy_const_generics,
1030 rustc_macro_transparency,
1033 rustc_nonnull_optimization_guaranteed,
1034 rustc_object_lifetime_default,
1035 rustc_on_unimplemented,
1038 rustc_partition_codegened,
1039 rustc_partition_reused,
1041 rustc_peek_definite_init,
1042 rustc_peek_indirectly_mutable,
1043 rustc_peek_liveness,
1044 rustc_peek_maybe_init,
1045 rustc_peek_maybe_uninit,
1046 rustc_polymorphize_error,
1048 rustc_proc_macro_decls,
1051 rustc_reservation_impl,
1053 rustc_skip_array_during_method_dispatch,
1054 rustc_specialization_trait,
1056 rustc_std_internal_symbol,
1060 rustc_then_this_would_need,
1061 rustc_unsafe_specialization_marker,
1065 rvalue_static_promotion,
1115 simd_reduce_add_ordered,
1116 simd_reduce_add_unordered,
1121 simd_reduce_max_nanless,
1123 simd_reduce_min_nanless,
1124 simd_reduce_mul_ordered,
1125 simd_reduce_mul_unordered,
1130 simd_saturating_add,
1131 simd_saturating_sub,
1134 simd_select_bitmask,
1162 sse4a_target_feature,
1174 std_panic_2015_macro,
1177 stmt_expr_attributes,
1178 stop_after_dataflow,
1183 struct_field_attributes,
1205 target_has_atomic_equal_alignment,
1206 target_has_atomic_load_store,
1208 target_pointer_width,
1209 target_target_vendor,
1210 target_thread_local,
1216 termination_trait_test,
1219 test_accepted_feature,
1221 test_removed_feature,
1248 type_alias_enum_variants,
1249 type_alias_impl_trait,
1260 unaligned_volatile_load,
1261 unaligned_volatile_store,
1270 underscore_const_names,
1272 underscore_lifetimes,
1275 universal_impl_trait,
1283 unrestricted_attribute_tokens,
1284 unsafe_block_in_unsafe_fn,
1286 unsafe_no_drop_flag,
1290 unsized_tuple_coercion,
1293 unused_qualifications,
1317 visible_private_types,
1319 volatile_copy_memory,
1320 volatile_copy_nonoverlapping_memory,
1322 volatile_set_memory,
1329 wasm_target_feature,
1345 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1353 /// Constructs a new identifier from a symbol and a span.
1354 pub const fn new(name: Symbol, span: Span) -> Ident {
1355 Ident { name, span }
1358 /// Constructs a new identifier with a dummy span.
1360 pub const fn with_dummy_span(name: Symbol) -> Ident {
1361 Ident::new(name, DUMMY_SP)
1365 pub fn invalid() -> Ident {
1366 Ident::with_dummy_span(kw::Empty)
1369 /// Maps a string to an identifier with a dummy span.
1370 pub fn from_str(string: &str) -> Ident {
1371 Ident::with_dummy_span(Symbol::intern(string))
1374 /// Maps a string and a span to an identifier.
1375 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1376 Ident::new(Symbol::intern(string), span)
1379 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1380 pub fn with_span_pos(self, span: Span) -> Ident {
1381 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1384 pub fn without_first_quote(self) -> Ident {
1385 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1388 /// "Normalize" ident for use in comparisons using "item hygiene".
1389 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1390 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1391 /// different macro 2.0 macros.
1392 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1393 pub fn normalize_to_macros_2_0(self) -> Ident {
1394 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1397 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1398 /// Identifiers with same string value become same if they came from the same non-transparent
1399 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1400 /// non-transparent macros.
1401 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1402 pub fn normalize_to_macro_rules(self) -> Ident {
1403 Ident::new(self.name, self.span.normalize_to_macro_rules())
1406 /// Convert the name to a `SymbolStr`. This is a slowish operation because
1407 /// it requires locking the symbol interner.
1408 pub fn as_str(self) -> SymbolStr {
1413 impl PartialEq for Ident {
1414 fn eq(&self, rhs: &Self) -> bool {
1415 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
1419 impl Hash for Ident {
1420 fn hash<H: Hasher>(&self, state: &mut H) {
1421 self.name.hash(state);
1422 self.span.ctxt().hash(state);
1426 impl fmt::Debug for Ident {
1427 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1428 fmt::Display::fmt(self, f)?;
1429 fmt::Debug::fmt(&self.span.ctxt(), f)
1433 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1434 /// to printing the original identifier token written in source code (`token_to_string`),
1435 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1436 impl fmt::Display for Ident {
1437 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1438 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1442 /// This is the most general way to print identifiers.
1443 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1444 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1445 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1446 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1447 /// hygiene data, most importantly name of the crate it refers to.
1448 /// As a result we print `$crate` as `crate` if it refers to the local crate
1449 /// and as `::other_crate_name` if it refers to some other crate.
1450 /// Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
1451 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1452 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1453 /// done for a token stream or a single token.
1454 pub struct IdentPrinter {
1457 /// Span used for retrieving the crate name to which `$crate` refers to,
1458 /// if this field is `None` then the `$crate` conversion doesn't happen.
1459 convert_dollar_crate: Option<Span>,
1463 /// The most general `IdentPrinter` constructor. Do not use this.
1464 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1465 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1468 /// This implementation is supposed to be used when printing identifiers
1469 /// as a part of pretty-printing for larger AST pieces.
1470 /// Do not use this either.
1471 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1472 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1476 impl fmt::Display for IdentPrinter {
1477 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1480 } else if self.symbol == kw::DollarCrate {
1481 if let Some(span) = self.convert_dollar_crate {
1482 let converted = span.ctxt().dollar_crate_name();
1483 if !converted.is_path_segment_keyword() {
1486 return fmt::Display::fmt(&converted, f);
1489 fmt::Display::fmt(&self.symbol, f)
1493 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1495 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1496 // `ModernIdent` struct and use that as well.
1497 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1498 pub struct MacroRulesNormalizedIdent(Ident);
1500 impl MacroRulesNormalizedIdent {
1501 pub fn new(ident: Ident) -> Self {
1502 Self(ident.normalize_to_macro_rules())
1506 impl fmt::Debug for MacroRulesNormalizedIdent {
1507 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1508 fmt::Debug::fmt(&self.0, f)
1512 impl fmt::Display for MacroRulesNormalizedIdent {
1513 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1514 fmt::Display::fmt(&self.0, f)
1518 /// An interned string.
1520 /// Internally, a `Symbol` is implemented as an index, and all operations
1521 /// (including hashing, equality, and ordering) operate on that index. The use
1522 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1523 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1525 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1526 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1527 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1528 pub struct Symbol(SymbolIndex);
1530 rustc_index::newtype_index! {
1531 pub struct SymbolIndex { .. }
1535 const fn new(n: u32) -> Self {
1536 Symbol(SymbolIndex::from_u32(n))
1539 /// Maps a string to its interned representation.
1540 pub fn intern(string: &str) -> Self {
1541 with_interner(|interner| interner.intern(string))
1544 /// Convert to a `SymbolStr`. This is a slowish operation because it
1545 /// requires locking the symbol interner.
1546 pub fn as_str(self) -> SymbolStr {
1547 with_interner(|interner| unsafe {
1548 SymbolStr { string: std::mem::transmute::<&str, &str>(interner.get(self)) }
1552 pub fn as_u32(self) -> u32 {
1556 pub fn is_empty(self) -> bool {
1560 /// This method is supposed to be used in error messages, so it's expected to be
1561 /// identical to printing the original identifier token written in source code
1562 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1563 /// or edition, so we have to guess the rawness using the global edition.
1564 pub fn to_ident_string(self) -> String {
1565 Ident::with_dummy_span(self).to_string()
1569 impl fmt::Debug for Symbol {
1570 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1571 fmt::Debug::fmt(&self.as_str(), f)
1575 impl fmt::Display for Symbol {
1576 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1577 fmt::Display::fmt(&self.as_str(), f)
1581 impl<S: Encoder> Encodable<S> for Symbol {
1582 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
1583 s.emit_str(&self.as_str())
1587 impl<D: Decoder> Decodable<D> for Symbol {
1589 fn decode(d: &mut D) -> Result<Symbol, D::Error> {
1590 Ok(Symbol::intern(&d.read_str()?))
1594 impl<CTX> HashStable<CTX> for Symbol {
1596 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1597 self.as_str().hash_stable(hcx, hasher);
1601 impl<CTX> ToStableHashKey<CTX> for Symbol {
1602 type KeyType = SymbolStr;
1605 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {
1610 // The `&'static str`s in this type actually point into the arena.
1612 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1613 // found that to regress performance up to 2% in some cases. This might be
1614 // revisited after further improvements to `indexmap`.
1616 pub struct Interner {
1617 arena: DroplessArena,
1618 names: FxHashMap<&'static str, Symbol>,
1619 strings: Vec<&'static str>,
1623 fn prefill(init: &[&'static str]) -> Self {
1625 strings: init.into(),
1626 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1627 ..Default::default()
1632 pub fn intern(&mut self, string: &str) -> Symbol {
1633 if let Some(&name) = self.names.get(string) {
1637 let name = Symbol::new(self.strings.len() as u32);
1639 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
1642 unsafe { str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes())) };
1643 // It is safe to extend the arena allocation to `'static` because we only access
1644 // these while the arena is still alive.
1645 let string: &'static str = unsafe { &*(string as *const str) };
1646 self.strings.push(string);
1647 self.names.insert(string, name);
1651 // Get the symbol as a string. `Symbol::as_str()` should be used in
1652 // preference to this function.
1653 pub fn get(&self, symbol: Symbol) -> &str {
1654 self.strings[symbol.0.as_usize()]
1658 // This module has a very short name because it's used a lot.
1659 /// This module contains all the defined keyword `Symbol`s.
1661 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1662 /// For example `kw::Loop` or `kw::Break`.
1664 pub use super::kw_generated::*;
1667 // This module has a very short name because it's used a lot.
1668 /// This module contains all the defined non-keyword `Symbol`s.
1670 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1671 /// For example `sym::rustfmt` or `sym::u8`.
1674 use std::convert::TryInto;
1677 pub use super::sym_generated::*;
1679 // Used from a macro in `librustc_feature/accepted.rs`
1680 pub use super::kw::MacroRules as macro_rules;
1682 /// Get the symbol for an integer.
1684 /// The first few non-negative integers each have a static symbol and therefore
1686 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1687 if let Result::Ok(idx) = n.try_into() {
1689 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
1692 Symbol::intern(&n.to_string())
1697 fn is_special(self) -> bool {
1698 self <= kw::Underscore
1701 fn is_used_keyword_always(self) -> bool {
1702 self >= kw::As && self <= kw::While
1705 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1706 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
1709 fn is_unused_keyword_always(self) -> bool {
1710 self >= kw::Abstract && self <= kw::Yield
1713 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1714 self == kw::Try && edition() >= Edition::Edition2018
1717 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
1719 || self.is_used_keyword_always()
1720 || self.is_unused_keyword_always()
1721 || self.is_used_keyword_conditional(edition)
1722 || self.is_unused_keyword_conditional(edition)
1725 /// A keyword or reserved identifier that can be used as a path segment.
1726 pub fn is_path_segment_keyword(self) -> bool {
1728 || self == kw::SelfLower
1729 || self == kw::SelfUpper
1730 || self == kw::Crate
1731 || self == kw::PathRoot
1732 || self == kw::DollarCrate
1735 /// Returns `true` if the symbol is `true` or `false`.
1736 pub fn is_bool_lit(self) -> bool {
1737 self == kw::True || self == kw::False
1740 /// Returns `true` if this symbol can be a raw identifier.
1741 pub fn can_be_raw(self) -> bool {
1742 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
1747 // Returns `true` for reserved identifiers used internally for elided lifetimes,
1748 // unnamed method parameters, crate root module, error recovery etc.
1749 pub fn is_special(self) -> bool {
1750 self.name.is_special()
1753 /// Returns `true` if the token is a keyword used in the language.
1754 pub fn is_used_keyword(self) -> bool {
1755 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1756 self.name.is_used_keyword_always()
1757 || self.name.is_used_keyword_conditional(|| self.span.edition())
1760 /// Returns `true` if the token is a keyword reserved for possible future use.
1761 pub fn is_unused_keyword(self) -> bool {
1762 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1763 self.name.is_unused_keyword_always()
1764 || self.name.is_unused_keyword_conditional(|| self.span.edition())
1767 /// Returns `true` if the token is either a special identifier or a keyword.
1768 pub fn is_reserved(self) -> bool {
1769 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1770 self.name.is_reserved(|| self.span.edition())
1773 /// A keyword or reserved identifier that can be used as a path segment.
1774 pub fn is_path_segment_keyword(self) -> bool {
1775 self.name.is_path_segment_keyword()
1778 /// We see this identifier in a normal identifier position, like variable name or a type.
1779 /// How was it written originally? Did it use the raw form? Let's try to guess.
1780 pub fn is_raw_guess(self) -> bool {
1781 self.name.can_be_raw() && self.is_reserved()
1786 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1787 SESSION_GLOBALS.with(|session_globals| f(&mut *session_globals.symbol_interner.lock()))
1790 /// An alternative to [`Symbol`], useful when the chars within the symbol need to
1791 /// be accessed. It deliberately has limited functionality and should only be
1792 /// used for temporary values.
1794 /// Because the interner outlives any thread which uses this type, we can
1795 /// safely treat `string` which points to interner data, as an immortal string,
1796 /// as long as this type never crosses between threads.
1798 // FIXME: ensure that the interner outlives any thread which uses `SymbolStr`,
1799 // by creating a new thread right after constructing the interner.
1800 #[derive(Clone, Eq, PartialOrd, Ord)]
1801 pub struct SymbolStr {
1802 string: &'static str,
1805 // This impl allows a `SymbolStr` to be directly equated with a `String` or
1807 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for SymbolStr {
1808 fn eq(&self, other: &T) -> bool {
1809 self.string == other.deref()
1813 impl !Send for SymbolStr {}
1814 impl !Sync for SymbolStr {}
1816 /// This impl means that if `ss` is a `SymbolStr`:
1817 /// - `*ss` is a `str`;
1818 /// - `&*ss` is a `&str` (and `match &*ss { ... }` is a common pattern).
1819 /// - `&ss as &str` is a `&str`, which means that `&ss` can be passed to a
1820 /// function expecting a `&str`.
1821 impl std::ops::Deref for SymbolStr {
1824 fn deref(&self) -> &str {
1829 impl fmt::Debug for SymbolStr {
1830 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1831 fmt::Debug::fmt(self.string, f)
1835 impl fmt::Display for SymbolStr {
1836 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1837 fmt::Display::fmt(self.string, f)
1841 impl<CTX> HashStable<CTX> for SymbolStr {
1843 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1844 self.string.hash_stable(hcx, hasher)
1848 impl<CTX> ToStableHashKey<CTX> for SymbolStr {
1849 type KeyType = SymbolStr;
1852 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {