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,
492 destructuring_assignment,
510 document_private_items,
511 dotdot_in_tuple_patterns,
512 dotdoteq_in_patterns,
520 dropck_parametricity,
529 emit_enum_variant_arg,
537 ermsb_target_feature,
541 exclusive_range_pattern,
542 exhaustive_integer_patterns,
553 extended_key_value_attributes,
554 extern_absolute_paths,
555 extern_crate_item_prelude,
577 field_init_shorthand,
582 float_to_int_unchecked,
612 from_size_align_unchecked,
626 generic_associated_types,
633 half_open_range_patterns,
637 hexagon_target_feature,
639 homogeneous_aggregate,
656 if_while_or_patterns,
658 impl_header_lifetime_elision,
661 impl_trait_in_bindings,
668 inclusive_range_syntax,
671 infer_outlives_requirements,
672 infer_static_outlives_requirements,
673 inherent_associated_types,
684 irrefutable_let_patterns,
688 issue_5723_bootstrap,
689 issue_tracker_base_url,
703 lazy_normalization_consts,
716 link_llvm_intrinsics,
735 macro_at_most_once_rep,
736 macro_attributes_in_derive_output,
739 macro_lifetime_matcher,
740 macro_literal_matcher,
752 match_beginning_vert,
753 match_default_bindings,
779 min_type_alias_impl_trait,
788 more_qualified_paths,
790 movbe_target_feature,
802 native_link_modifiers,
803 native_link_modifiers_as_needed,
804 native_link_modifiers_bundle,
805 native_link_modifiers_verbatim,
806 native_link_modifiers_whole_archive,
854 object_safe_for_dispatch,
857 omit_gdb_pretty_printer_section,
866 optin_builtin_traits,
875 overlapping_marker_traits,
885 panic_implementation,
914 post_dash_lto: "post-lto",
915 powerpc_target_feature,
920 pre_dash_lto: "pre-lto",
921 precise_pointer_size_matching,
925 prefetch_read_instruction,
927 prefetch_write_instruction,
933 proc_dash_macro: "proc-macro",
935 proc_macro_attribute,
941 proc_macro_internals,
943 proc_macro_non_items,
944 proc_macro_path_invoc,
959 quad_precision_float,
967 re_rebalance_coherence,
970 read_enum_variant_arg,
978 reexport_test_harness_main,
979 ref_unwind_safe_trait,
993 relaxed_struct_unsize,
1010 riscv_target_feature,
1026 rust_eh_catch_typeinfo,
1027 rust_eh_personality,
1028 rust_eh_register_frames,
1029 rust_eh_unregister_frames,
1033 rustc_allocator_nounwind,
1034 rustc_allow_const_fn_unstable,
1036 rustc_builtin_macro,
1037 rustc_capture_analysis,
1040 rustc_const_unstable,
1041 rustc_conversion_suggestion,
1044 rustc_diagnostic_item,
1045 rustc_diagnostic_macros,
1048 rustc_dump_env_program_clauses,
1049 rustc_dump_program_clauses,
1050 rustc_dump_user_substs,
1053 rustc_evaluate_where_clauses,
1054 rustc_expected_cgu_reuse,
1055 rustc_if_this_changed,
1056 rustc_inherit_overflow_checks,
1057 rustc_insignificant_dtor,
1059 rustc_layout_scalar_valid_range_end,
1060 rustc_layout_scalar_valid_range_start,
1061 rustc_legacy_const_generics,
1062 rustc_macro_transparency,
1065 rustc_nonnull_optimization_guaranteed,
1066 rustc_object_lifetime_default,
1067 rustc_on_unimplemented,
1070 rustc_partition_codegened,
1071 rustc_partition_reused,
1073 rustc_peek_definite_init,
1074 rustc_peek_indirectly_mutable,
1075 rustc_peek_liveness,
1076 rustc_peek_maybe_init,
1077 rustc_peek_maybe_uninit,
1078 rustc_polymorphize_error,
1080 rustc_proc_macro_decls,
1083 rustc_reservation_impl,
1085 rustc_skip_array_during_method_dispatch,
1086 rustc_specialization_trait,
1088 rustc_std_internal_symbol,
1092 rustc_then_this_would_need,
1093 rustc_unsafe_specialization_marker,
1097 rvalue_static_promotion,
1147 simd_reduce_add_ordered,
1148 simd_reduce_add_unordered,
1153 simd_reduce_max_nanless,
1155 simd_reduce_min_nanless,
1156 simd_reduce_mul_ordered,
1157 simd_reduce_mul_unordered,
1162 simd_saturating_add,
1163 simd_saturating_sub,
1166 simd_select_bitmask,
1195 sse4a_target_feature,
1207 std_panic_2015_macro,
1210 stmt_expr_attributes,
1211 stop_after_dataflow,
1216 struct_field_attributes,
1239 target_has_atomic_equal_alignment,
1240 target_has_atomic_load_store,
1242 target_pointer_width,
1243 target_target_vendor,
1244 target_thread_local,
1250 termination_trait_test,
1253 test_accepted_feature,
1255 test_removed_feature,
1284 type_alias_enum_variants,
1285 type_alias_impl_trait,
1296 unaligned_volatile_load,
1297 unaligned_volatile_store,
1306 underscore_const_names,
1308 underscore_lifetimes,
1311 universal_impl_trait,
1319 unrestricted_attribute_tokens,
1320 unsafe_block_in_unsafe_fn,
1322 unsafe_no_drop_flag,
1326 unsized_tuple_coercion,
1329 unused_qualifications,
1353 visible_private_types,
1355 volatile_copy_memory,
1356 volatile_copy_nonoverlapping_memory,
1358 volatile_set_memory,
1365 wasm_target_feature,
1382 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1390 /// Constructs a new identifier from a symbol and a span.
1391 pub const fn new(name: Symbol, span: Span) -> Ident {
1392 Ident { name, span }
1395 /// Constructs a new identifier with a dummy span.
1397 pub const fn with_dummy_span(name: Symbol) -> Ident {
1398 Ident::new(name, DUMMY_SP)
1402 pub fn invalid() -> Ident {
1403 Ident::with_dummy_span(kw::Empty)
1406 /// Maps a string to an identifier with a dummy span.
1407 pub fn from_str(string: &str) -> Ident {
1408 Ident::with_dummy_span(Symbol::intern(string))
1411 /// Maps a string and a span to an identifier.
1412 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1413 Ident::new(Symbol::intern(string), span)
1416 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1417 pub fn with_span_pos(self, span: Span) -> Ident {
1418 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1421 pub fn without_first_quote(self) -> Ident {
1422 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1425 /// "Normalize" ident for use in comparisons using "item hygiene".
1426 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1427 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1428 /// different macro 2.0 macros.
1429 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1430 pub fn normalize_to_macros_2_0(self) -> Ident {
1431 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1434 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1435 /// Identifiers with same string value become same if they came from the same non-transparent
1436 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1437 /// non-transparent macros.
1438 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1439 pub fn normalize_to_macro_rules(self) -> Ident {
1440 Ident::new(self.name, self.span.normalize_to_macro_rules())
1443 /// Convert the name to a `SymbolStr`. This is a slowish operation because
1444 /// it requires locking the symbol interner.
1445 pub fn as_str(self) -> SymbolStr {
1450 impl PartialEq for Ident {
1451 fn eq(&self, rhs: &Self) -> bool {
1452 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
1456 impl Hash for Ident {
1457 fn hash<H: Hasher>(&self, state: &mut H) {
1458 self.name.hash(state);
1459 self.span.ctxt().hash(state);
1463 impl fmt::Debug for Ident {
1464 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1465 fmt::Display::fmt(self, f)?;
1466 fmt::Debug::fmt(&self.span.ctxt(), f)
1470 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1471 /// to printing the original identifier token written in source code (`token_to_string`),
1472 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1473 impl fmt::Display for Ident {
1474 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1475 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1479 /// This is the most general way to print identifiers.
1480 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1481 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1482 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1483 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1484 /// hygiene data, most importantly name of the crate it refers to.
1485 /// As a result we print `$crate` as `crate` if it refers to the local crate
1486 /// and as `::other_crate_name` if it refers to some other crate.
1487 /// Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
1488 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1489 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1490 /// done for a token stream or a single token.
1491 pub struct IdentPrinter {
1494 /// Span used for retrieving the crate name to which `$crate` refers to,
1495 /// if this field is `None` then the `$crate` conversion doesn't happen.
1496 convert_dollar_crate: Option<Span>,
1500 /// The most general `IdentPrinter` constructor. Do not use this.
1501 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1502 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1505 /// This implementation is supposed to be used when printing identifiers
1506 /// as a part of pretty-printing for larger AST pieces.
1507 /// Do not use this either.
1508 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1509 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1513 impl fmt::Display for IdentPrinter {
1514 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1517 } else if self.symbol == kw::DollarCrate {
1518 if let Some(span) = self.convert_dollar_crate {
1519 let converted = span.ctxt().dollar_crate_name();
1520 if !converted.is_path_segment_keyword() {
1523 return fmt::Display::fmt(&converted, f);
1526 fmt::Display::fmt(&self.symbol, f)
1530 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1532 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1533 // `ModernIdent` struct and use that as well.
1534 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1535 pub struct MacroRulesNormalizedIdent(Ident);
1537 impl MacroRulesNormalizedIdent {
1538 pub fn new(ident: Ident) -> Self {
1539 Self(ident.normalize_to_macro_rules())
1543 impl fmt::Debug for MacroRulesNormalizedIdent {
1544 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1545 fmt::Debug::fmt(&self.0, f)
1549 impl fmt::Display for MacroRulesNormalizedIdent {
1550 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1551 fmt::Display::fmt(&self.0, f)
1555 /// An interned string.
1557 /// Internally, a `Symbol` is implemented as an index, and all operations
1558 /// (including hashing, equality, and ordering) operate on that index. The use
1559 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1560 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1562 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1563 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1564 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1565 pub struct Symbol(SymbolIndex);
1567 rustc_index::newtype_index! {
1568 pub struct SymbolIndex { .. }
1572 const fn new(n: u32) -> Self {
1573 Symbol(SymbolIndex::from_u32(n))
1576 /// Maps a string to its interned representation.
1577 pub fn intern(string: &str) -> Self {
1578 with_interner(|interner| interner.intern(string))
1581 /// Convert to a `SymbolStr`. This is a slowish operation because it
1582 /// requires locking the symbol interner.
1583 pub fn as_str(self) -> SymbolStr {
1584 with_interner(|interner| unsafe {
1585 SymbolStr { string: std::mem::transmute::<&str, &str>(interner.get(self)) }
1589 pub fn as_u32(self) -> u32 {
1593 pub fn is_empty(self) -> bool {
1597 /// This method is supposed to be used in error messages, so it's expected to be
1598 /// identical to printing the original identifier token written in source code
1599 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1600 /// or edition, so we have to guess the rawness using the global edition.
1601 pub fn to_ident_string(self) -> String {
1602 Ident::with_dummy_span(self).to_string()
1606 impl fmt::Debug for Symbol {
1607 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1608 fmt::Debug::fmt(&self.as_str(), f)
1612 impl fmt::Display for Symbol {
1613 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1614 fmt::Display::fmt(&self.as_str(), f)
1618 impl<S: Encoder> Encodable<S> for Symbol {
1619 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
1620 s.emit_str(&self.as_str())
1624 impl<D: Decoder> Decodable<D> for Symbol {
1626 fn decode(d: &mut D) -> Result<Symbol, D::Error> {
1627 Ok(Symbol::intern(&d.read_str()?))
1631 impl<CTX> HashStable<CTX> for Symbol {
1633 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1634 self.as_str().hash_stable(hcx, hasher);
1638 impl<CTX> ToStableHashKey<CTX> for Symbol {
1639 type KeyType = SymbolStr;
1642 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {
1647 // The `&'static str`s in this type actually point into the arena.
1649 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1650 // found that to regress performance up to 2% in some cases. This might be
1651 // revisited after further improvements to `indexmap`.
1653 pub struct Interner {
1654 arena: DroplessArena,
1655 names: FxHashMap<&'static str, Symbol>,
1656 strings: Vec<&'static str>,
1660 fn prefill(init: &[&'static str]) -> Self {
1662 strings: init.into(),
1663 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1664 ..Default::default()
1669 pub fn intern(&mut self, string: &str) -> Symbol {
1670 if let Some(&name) = self.names.get(string) {
1674 let name = Symbol::new(self.strings.len() as u32);
1676 // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
1679 unsafe { str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes())) };
1680 // It is safe to extend the arena allocation to `'static` because we only access
1681 // these while the arena is still alive.
1682 let string: &'static str = unsafe { &*(string as *const str) };
1683 self.strings.push(string);
1684 self.names.insert(string, name);
1688 // Get the symbol as a string. `Symbol::as_str()` should be used in
1689 // preference to this function.
1690 pub fn get(&self, symbol: Symbol) -> &str {
1691 self.strings[symbol.0.as_usize()]
1695 // This module has a very short name because it's used a lot.
1696 /// This module contains all the defined keyword `Symbol`s.
1698 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1699 /// For example `kw::Loop` or `kw::Break`.
1701 pub use super::kw_generated::*;
1704 // This module has a very short name because it's used a lot.
1705 /// This module contains all the defined non-keyword `Symbol`s.
1707 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1708 /// For example `sym::rustfmt` or `sym::u8`.
1711 use std::convert::TryInto;
1714 pub use super::sym_generated::*;
1716 // Used from a macro in `librustc_feature/accepted.rs`
1717 pub use super::kw::MacroRules as macro_rules;
1719 /// Get the symbol for an integer.
1721 /// The first few non-negative integers each have a static symbol and therefore
1723 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1724 if let Result::Ok(idx) = n.try_into() {
1726 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
1729 Symbol::intern(&n.to_string())
1734 fn is_special(self) -> bool {
1735 self <= kw::Underscore
1738 fn is_used_keyword_always(self) -> bool {
1739 self >= kw::As && self <= kw::While
1742 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1743 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
1746 fn is_unused_keyword_always(self) -> bool {
1747 self >= kw::Abstract && self <= kw::Yield
1750 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1751 self == kw::Try && edition() >= Edition::Edition2018
1754 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
1756 || self.is_used_keyword_always()
1757 || self.is_unused_keyword_always()
1758 || self.is_used_keyword_conditional(edition)
1759 || self.is_unused_keyword_conditional(edition)
1762 /// A keyword or reserved identifier that can be used as a path segment.
1763 pub fn is_path_segment_keyword(self) -> bool {
1765 || self == kw::SelfLower
1766 || self == kw::SelfUpper
1767 || self == kw::Crate
1768 || self == kw::PathRoot
1769 || self == kw::DollarCrate
1772 /// Returns `true` if the symbol is `true` or `false`.
1773 pub fn is_bool_lit(self) -> bool {
1774 self == kw::True || self == kw::False
1777 /// Returns `true` if this symbol can be a raw identifier.
1778 pub fn can_be_raw(self) -> bool {
1779 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
1784 // Returns `true` for reserved identifiers used internally for elided lifetimes,
1785 // unnamed method parameters, crate root module, error recovery etc.
1786 pub fn is_special(self) -> bool {
1787 self.name.is_special()
1790 /// Returns `true` if the token is a keyword used in the language.
1791 pub fn is_used_keyword(self) -> bool {
1792 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1793 self.name.is_used_keyword_always()
1794 || self.name.is_used_keyword_conditional(|| self.span.edition())
1797 /// Returns `true` if the token is a keyword reserved for possible future use.
1798 pub fn is_unused_keyword(self) -> bool {
1799 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1800 self.name.is_unused_keyword_always()
1801 || self.name.is_unused_keyword_conditional(|| self.span.edition())
1804 /// Returns `true` if the token is either a special identifier or a keyword.
1805 pub fn is_reserved(self) -> bool {
1806 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1807 self.name.is_reserved(|| self.span.edition())
1810 /// A keyword or reserved identifier that can be used as a path segment.
1811 pub fn is_path_segment_keyword(self) -> bool {
1812 self.name.is_path_segment_keyword()
1815 /// We see this identifier in a normal identifier position, like variable name or a type.
1816 /// How was it written originally? Did it use the raw form? Let's try to guess.
1817 pub fn is_raw_guess(self) -> bool {
1818 self.name.can_be_raw() && self.is_reserved()
1823 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1824 with_session_globals(|session_globals| f(&mut *session_globals.symbol_interner.lock()))
1827 /// An alternative to [`Symbol`], useful when the chars within the symbol need to
1828 /// be accessed. It deliberately has limited functionality and should only be
1829 /// used for temporary values.
1831 /// Because the interner outlives any thread which uses this type, we can
1832 /// safely treat `string` which points to interner data, as an immortal string,
1833 /// as long as this type never crosses between threads.
1835 // FIXME: ensure that the interner outlives any thread which uses `SymbolStr`,
1836 // by creating a new thread right after constructing the interner.
1837 #[derive(Clone, Eq, PartialOrd, Ord)]
1838 pub struct SymbolStr {
1839 string: &'static str,
1842 // This impl allows a `SymbolStr` to be directly equated with a `String` or
1844 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for SymbolStr {
1845 fn eq(&self, other: &T) -> bool {
1846 self.string == other.deref()
1850 impl !Send for SymbolStr {}
1851 impl !Sync for SymbolStr {}
1853 /// This impl means that if `ss` is a `SymbolStr`:
1854 /// - `*ss` is a `str`;
1855 /// - `&*ss` is a `&str` (and `match &*ss { ... }` is a common pattern).
1856 /// - `&ss as &str` is a `&str`, which means that `&ss` can be passed to a
1857 /// function expecting a `&str`.
1858 impl std::ops::Deref for SymbolStr {
1861 fn deref(&self) -> &str {
1866 impl fmt::Debug for SymbolStr {
1867 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1868 fmt::Debug::fmt(self.string, f)
1872 impl fmt::Display for SymbolStr {
1873 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1874 fmt::Display::fmt(self.string, f)
1878 impl<CTX> HashStable<CTX> for SymbolStr {
1880 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1881 self.string.hash_stable(hcx, hasher)
1885 impl<CTX> ToStableHashKey<CTX> for SymbolStr {
1886 type KeyType = SymbolStr;
1889 fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {