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_data_structures::sync::Lock;
9 use rustc_macros::HashStable_Generic;
10 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
12 use std::cmp::{Ord, PartialEq, PartialOrd};
14 use std::hash::{Hash, Hasher};
17 use crate::{with_session_globals, Edition, Span, DUMMY_SP};
22 // The proc macro code for this is in `compiler/rustc_macros/src/symbols.rs`.
24 // After modifying this list adjust `is_special`, `is_used_keyword`/`is_unused_keyword`,
25 // this should be rarely necessary though if the keywords are kept in alphabetic order.
27 // Special reserved identifiers used internally for elided lifetimes,
28 // unnamed method parameters, crate root module, error recovery etc.
31 DollarCrate: "$crate",
34 // Keywords that are used in stable Rust.
71 // Keywords that are used in unstable Rust or reserved for future use.
85 // Edition-specific keywords that are used in stable Rust.
86 Async: "async", // >= 2018 Edition only
87 Await: "await", // >= 2018 Edition only
88 Dyn: "dyn", // >= 2018 Edition only
90 // Edition-specific keywords that are used in unstable Rust or reserved for future use.
91 Try: "try", // >= 2018 Edition only
93 // Special lifetime names
94 UnderscoreLifetime: "'_",
95 StaticLifetime: "'static",
97 // Weak keywords, have special meaning only in specific contexts.
101 MacroRules: "macro_rules",
106 // Pre-interned symbols that can be referred to with `rustc_span::sym::*`.
108 // The symbol is the stringified identifier unless otherwise specified, in
109 // which case the name should mention the non-identifier punctuation.
110 // E.g. `sym::proc_dash_macro` represents "proc-macro", and it shouldn't be
111 // called `sym::proc_macro` because then it's easy to mistakenly think it
112 // represents "proc_macro".
114 // As well as the symbols listed, there are symbols for the strings
115 // "0", "1", ..., "9", which are accessible via `sym::integer`.
117 // The proc macro will abort if symbols are not in alphabetical order (as
118 // defined by `impl Ord for str`) or if any symbols are duplicated. Vim
119 // users can sort the list by selecting it and executing the command
120 // `:'<,'>!LC_ALL=C sort`.
122 // There is currently no checking that all symbols are used; that would be
231 ProceduralMasqueradeDummyType,
280 aarch64_target_feature,
284 abi_c_cmse_nonsecure_call,
286 abi_msp430_interrupt,
300 advanced_slice_patterns,
316 allow_internal_unsafe,
317 allow_internal_unstable,
325 arbitrary_enum_discriminant,
326 arbitrary_self_types,
337 asm_experimental_arch,
345 assert_receiver_is_total_eq,
348 associated_const_equality,
350 associated_type_bounds,
351 associated_type_defaults,
364 augmented_assignments,
366 automatically_derived,
368 avx512_target_feature,
376 bind_by_move_pattern_guards,
388 borrowck_graphviz_format,
389 borrowck_graphviz_postflow,
390 borrowck_graphviz_preflow,
395 braced_empty_structs,
407 capture_disjoint_fields,
423 cfg_target_has_atomic,
424 cfg_target_thread_local,
436 closure_to_fn_coercion,
437 closure_track_caller,
441 cmpxchg16b_target_feature,
442 cmse_nonsecure_entry,
449 compare_exchange_weak,
458 conservative_impl_trait,
462 const_compare_raw_pointers,
466 const_eval_select_ct,
467 const_evaluatable_checked,
470 const_fn_floating_point_arithmetic,
471 const_fn_fn_ptr_basics,
472 const_fn_trait_bound,
478 const_generic_defaults,
480 const_generics_defaults,
483 const_in_array_repeat_expressions,
490 const_precise_live_drops,
493 const_raw_ptr_to_usize_cast,
496 const_trait_bound_opt_out,
513 core_panic_2015_macro,
524 crate_visibility_modifier,
525 crt_dash_static: "crt-static",
534 custom_inner_attributes,
535 custom_test_frameworks,
541 debug_assert_eq_macro,
543 debug_assert_ne_macro,
551 default_alloc_error_handler,
552 default_lib_allocator,
553 default_method_body_is_const,
554 default_type_parameter_fallback,
556 delay_span_bug_from_inside_query,
565 destructuring_assignment,
586 document_private_items,
588 dotdot_in_tuple_patterns,
589 dotdoteq_in_patterns,
597 dropck_parametricity,
608 emit_enum_variant_arg,
620 ermsb_target_feature,
624 exclusive_range_pattern,
625 exhaustive_integer_patterns,
634 explicit_generic_args_with_impl_trait,
637 extended_key_value_attributes,
638 extern_absolute_paths,
639 extern_crate_item_prelude,
664 field_init_shorthand,
670 float_to_int_unchecked,
703 from_size_align_unchecked,
717 generic_associated_types,
725 half_open_range_patterns,
727 hexagon_target_feature,
729 homogeneous_aggregate,
746 if_while_or_patterns,
748 impl_header_lifetime_elision,
751 impl_trait_in_bindings,
761 inclusive_range_syntax,
764 infer_outlives_requirements,
765 infer_static_outlives_requirements,
766 inherent_associated_types,
778 irrefutable_let_patterns,
782 issue_5723_bootstrap,
783 issue_tracker_base_url,
797 lazy_normalization_consts,
812 link_llvm_intrinsics,
832 macro_at_most_once_rep,
833 macro_attributes_in_derive_output,
836 macro_lifetime_matcher,
837 macro_literal_matcher,
849 match_beginning_vert,
850 match_default_bindings,
879 min_type_alias_impl_trait,
889 more_qualified_paths,
891 movbe_target_feature,
904 native_link_modifiers,
905 native_link_modifiers_as_needed,
906 native_link_modifiers_bundle,
907 native_link_modifiers_verbatim,
908 native_link_modifiers_whole_archive,
946 non_exhaustive_omitted_patterns_lint,
958 object_safe_for_dispatch,
961 omit_gdb_pretty_printer_section,
970 optin_builtin_traits,
979 overlapping_marker_traits,
991 panic_implementation,
1006 pattern_parentheses,
1010 platform_intrinsics,
1019 post_dash_lto: "post-lto",
1020 powerpc_target_feature,
1025 pre_dash_lto: "pre-lto",
1026 precise_pointer_size_matching,
1030 prefetch_read_instruction,
1031 prefetch_write_data,
1032 prefetch_write_instruction,
1040 proc_dash_macro: "proc-macro",
1042 proc_macro_attribute,
1043 proc_macro_def_site,
1048 proc_macro_internals,
1050 proc_macro_non_items,
1051 proc_macro_path_invoc,
1066 quad_precision_float,
1069 range_inclusive_new,
1074 re_rebalance_coherence,
1077 read_enum_variant_arg,
1085 reexport_test_harness_main,
1086 ref_unwind_safe_trait,
1103 relaxed_struct_unsize,
1114 reserved_r9: "reserved-r9",
1120 riscv_target_feature,
1136 rust_eh_catch_typeinfo,
1137 rust_eh_personality,
1138 rust_eh_register_frames,
1139 rust_eh_unregister_frames,
1143 rustc_allocator_nounwind,
1144 rustc_allow_const_fn_unstable,
1146 rustc_builtin_macro,
1147 rustc_capture_analysis,
1150 rustc_const_unstable,
1151 rustc_conversion_suggestion,
1154 rustc_diagnostic_item,
1155 rustc_diagnostic_macros,
1157 rustc_do_not_const_check,
1159 rustc_dump_env_program_clauses,
1160 rustc_dump_program_clauses,
1161 rustc_dump_user_substs,
1164 rustc_evaluate_where_clauses,
1165 rustc_expected_cgu_reuse,
1166 rustc_if_this_changed,
1167 rustc_inherit_overflow_checks,
1168 rustc_insignificant_dtor,
1170 rustc_layout_scalar_valid_range_end,
1171 rustc_layout_scalar_valid_range_start,
1172 rustc_legacy_const_generics,
1173 rustc_macro_transparency,
1176 rustc_must_implement_one_of,
1177 rustc_nonnull_optimization_guaranteed,
1178 rustc_object_lifetime_default,
1179 rustc_on_unimplemented,
1182 rustc_partition_codegened,
1183 rustc_partition_reused,
1184 rustc_pass_by_value,
1186 rustc_peek_definite_init,
1187 rustc_peek_liveness,
1188 rustc_peek_maybe_init,
1189 rustc_peek_maybe_uninit,
1190 rustc_polymorphize_error,
1192 rustc_proc_macro_decls,
1195 rustc_reservation_impl,
1197 rustc_skip_array_during_method_dispatch,
1198 rustc_specialization_trait,
1200 rustc_std_internal_symbol,
1201 rustc_strict_coherence,
1204 rustc_then_this_would_need,
1205 rustc_trivial_field_reads,
1206 rustc_unsafe_specialization_marker,
1208 rustc_with_negative_coherence,
1212 rvalue_static_promotion,
1262 simd_reduce_add_ordered,
1263 simd_reduce_add_unordered,
1268 simd_reduce_max_nanless,
1270 simd_reduce_min_nanless,
1271 simd_reduce_mul_ordered,
1272 simd_reduce_mul_unordered,
1277 simd_saturating_add,
1278 simd_saturating_sub,
1281 simd_select_bitmask,
1312 sse4a_target_feature,
1324 std_panic_2015_macro,
1327 stmt_expr_attributes,
1328 stop_after_dataflow,
1334 struct_field_attributes,
1356 target_has_atomic_equal_alignment,
1357 target_has_atomic_load_store,
1359 target_pointer_width,
1360 target_target_vendor,
1361 target_thread_local,
1367 termination_trait_test,
1370 test_accepted_feature,
1372 test_removed_feature,
1379 thumb_mode: "thumb-mode",
1404 type_alias_enum_variants,
1405 type_alias_impl_trait,
1407 type_changing_struct_update,
1417 unaligned_volatile_load,
1418 unaligned_volatile_store,
1427 underscore_const_names,
1429 underscore_lifetimes,
1431 unimplemented_macro,
1433 universal_impl_trait,
1441 unrestricted_attribute_tokens,
1442 unsafe_block_in_unsafe_fn,
1444 unsafe_no_drop_flag,
1448 unsized_tuple_coercion,
1451 unused_qualifications,
1475 visible_private_types,
1477 volatile_copy_memory,
1478 volatile_copy_nonoverlapping_memory,
1480 volatile_set_memory,
1487 wasm_target_feature,
1508 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1516 /// Constructs a new identifier from a symbol and a span.
1517 pub const fn new(name: Symbol, span: Span) -> Ident {
1518 Ident { name, span }
1521 /// Constructs a new identifier with a dummy span.
1523 pub const fn with_dummy_span(name: Symbol) -> Ident {
1524 Ident::new(name, DUMMY_SP)
1528 pub fn empty() -> Ident {
1529 Ident::with_dummy_span(kw::Empty)
1532 /// Maps a string to an identifier with a dummy span.
1533 pub fn from_str(string: &str) -> Ident {
1534 Ident::with_dummy_span(Symbol::intern(string))
1537 /// Maps a string and a span to an identifier.
1538 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1539 Ident::new(Symbol::intern(string), span)
1542 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1543 pub fn with_span_pos(self, span: Span) -> Ident {
1544 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1547 pub fn without_first_quote(self) -> Ident {
1548 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1551 /// "Normalize" ident for use in comparisons using "item hygiene".
1552 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1553 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1554 /// different macro 2.0 macros.
1555 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1556 pub fn normalize_to_macros_2_0(self) -> Ident {
1557 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1560 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1561 /// Identifiers with same string value become same if they came from the same non-transparent
1562 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1563 /// non-transparent macros.
1564 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1565 pub fn normalize_to_macro_rules(self) -> Ident {
1566 Ident::new(self.name, self.span.normalize_to_macro_rules())
1569 /// Access the underlying string. This is a slowish operation because it
1570 /// requires locking the symbol interner.
1572 /// Note that the lifetime of the return value is a lie. See
1573 /// `Symbol::as_str()` for details.
1574 pub fn as_str(&self) -> &str {
1579 impl PartialEq for Ident {
1580 fn eq(&self, rhs: &Self) -> bool {
1581 self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
1585 impl Hash for Ident {
1586 fn hash<H: Hasher>(&self, state: &mut H) {
1587 self.name.hash(state);
1588 self.span.ctxt().hash(state);
1592 impl fmt::Debug for Ident {
1593 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1594 fmt::Display::fmt(self, f)?;
1595 fmt::Debug::fmt(&self.span.ctxt(), f)
1599 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1600 /// to printing the original identifier token written in source code (`token_to_string`),
1601 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1602 impl fmt::Display for Ident {
1603 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1604 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1608 /// This is the most general way to print identifiers.
1609 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1610 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1611 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1612 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1613 /// hygiene data, most importantly name of the crate it refers to.
1614 /// As a result we print `$crate` as `crate` if it refers to the local crate
1615 /// and as `::other_crate_name` if it refers to some other crate.
1616 /// Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
1617 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1618 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1619 /// done for a token stream or a single token.
1620 pub struct IdentPrinter {
1623 /// Span used for retrieving the crate name to which `$crate` refers to,
1624 /// if this field is `None` then the `$crate` conversion doesn't happen.
1625 convert_dollar_crate: Option<Span>,
1629 /// The most general `IdentPrinter` constructor. Do not use this.
1630 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1631 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1634 /// This implementation is supposed to be used when printing identifiers
1635 /// as a part of pretty-printing for larger AST pieces.
1636 /// Do not use this either.
1637 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1638 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1642 impl fmt::Display for IdentPrinter {
1643 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1646 } else if self.symbol == kw::DollarCrate {
1647 if let Some(span) = self.convert_dollar_crate {
1648 let converted = span.ctxt().dollar_crate_name();
1649 if !converted.is_path_segment_keyword() {
1652 return fmt::Display::fmt(&converted, f);
1655 fmt::Display::fmt(&self.symbol, f)
1659 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1661 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1662 // `ModernIdent` struct and use that as well.
1663 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1664 pub struct MacroRulesNormalizedIdent(Ident);
1666 impl MacroRulesNormalizedIdent {
1667 pub fn new(ident: Ident) -> Self {
1668 Self(ident.normalize_to_macro_rules())
1672 impl fmt::Debug for MacroRulesNormalizedIdent {
1673 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1674 fmt::Debug::fmt(&self.0, f)
1678 impl fmt::Display for MacroRulesNormalizedIdent {
1679 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1680 fmt::Display::fmt(&self.0, f)
1684 /// An interned string.
1686 /// Internally, a `Symbol` is implemented as an index, and all operations
1687 /// (including hashing, equality, and ordering) operate on that index. The use
1688 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1689 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1691 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1692 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1693 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1694 pub struct Symbol(SymbolIndex);
1696 rustc_index::newtype_index! {
1697 struct SymbolIndex { .. }
1701 const fn new(n: u32) -> Self {
1702 Symbol(SymbolIndex::from_u32(n))
1705 /// Maps a string to its interned representation.
1706 pub fn intern(string: &str) -> Self {
1707 with_session_globals(|session_globals| session_globals.symbol_interner.intern(string))
1710 /// Access the underlying string. This is a slowish operation because it
1711 /// requires locking the symbol interner.
1713 /// Note that the lifetime of the return value is a lie. It's not the same
1714 /// as `&self`, but actually tied to the lifetime of the underlying
1715 /// interner. Interners are long-lived, and there are very few of them, and
1716 /// this function is typically used for short-lived things, so in practice
1717 /// it works out ok.
1718 pub fn as_str(&self) -> &str {
1719 with_session_globals(|session_globals| unsafe {
1720 std::mem::transmute::<&str, &str>(session_globals.symbol_interner.get(*self))
1724 pub fn as_u32(self) -> u32 {
1728 pub fn is_empty(self) -> bool {
1732 /// This method is supposed to be used in error messages, so it's expected to be
1733 /// identical to printing the original identifier token written in source code
1734 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1735 /// or edition, so we have to guess the rawness using the global edition.
1736 pub fn to_ident_string(self) -> String {
1737 Ident::with_dummy_span(self).to_string()
1741 impl fmt::Debug for Symbol {
1742 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1743 fmt::Debug::fmt(self.as_str(), f)
1747 impl fmt::Display for Symbol {
1748 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1749 fmt::Display::fmt(self.as_str(), f)
1753 impl<S: Encoder> Encodable<S> for Symbol {
1754 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
1755 s.emit_str(self.as_str())
1759 impl<D: Decoder> Decodable<D> for Symbol {
1761 fn decode(d: &mut D) -> Symbol {
1762 Symbol::intern(&d.read_str())
1766 impl<CTX> HashStable<CTX> for Symbol {
1768 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1769 self.as_str().hash_stable(hcx, hasher);
1773 impl<CTX> ToStableHashKey<CTX> for Symbol {
1774 type KeyType = String;
1776 fn to_stable_hash_key(&self, _: &CTX) -> String {
1777 self.as_str().to_string()
1782 pub(crate) struct Interner(Lock<InternerInner>);
1784 // The `&'static str`s in this type actually point into the arena.
1786 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1787 // found that to regress performance up to 2% in some cases. This might be
1788 // revisited after further improvements to `indexmap`.
1790 // This type is private to prevent accidentally constructing more than one
1791 // `Interner` on the same thread, which makes it easy to mixup `Symbol`s
1792 // between `Interner`s.
1794 struct InternerInner {
1795 arena: DroplessArena,
1796 names: FxHashMap<&'static str, Symbol>,
1797 strings: Vec<&'static str>,
1801 fn prefill(init: &[&'static str]) -> Self {
1802 Interner(Lock::new(InternerInner {
1803 strings: init.into(),
1804 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1805 ..Default::default()
1810 fn intern(&self, string: &str) -> Symbol {
1811 let mut inner = self.0.lock();
1812 if let Some(&name) = inner.names.get(string) {
1816 let name = Symbol::new(inner.strings.len() as u32);
1818 // SAFETY: we convert from `&str` to `&[u8]`, clone it into the arena,
1819 // and immediately convert the clone back to `&[u8], all because there
1820 // is no `inner.arena.alloc_str()` method. This is clearly safe.
1822 unsafe { str::from_utf8_unchecked(inner.arena.alloc_slice(string.as_bytes())) };
1824 // SAFETY: we can extend the arena allocation to `'static` because we
1825 // only access these while the arena is still alive.
1826 let string: &'static str = unsafe { &*(string as *const str) };
1827 inner.strings.push(string);
1829 // This second hash table lookup can be avoided by using `RawEntryMut`,
1830 // but this code path isn't hot enough for it to be worth it. See
1831 // #91445 for details.
1832 inner.names.insert(string, name);
1836 // Get the symbol as a string. `Symbol::as_str()` should be used in
1837 // preference to this function.
1838 fn get(&self, symbol: Symbol) -> &str {
1839 self.0.lock().strings[symbol.0.as_usize()]
1843 // This module has a very short name because it's used a lot.
1844 /// This module contains all the defined keyword `Symbol`s.
1846 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1847 /// For example `kw::Loop` or `kw::Break`.
1849 pub use super::kw_generated::*;
1852 // This module has a very short name because it's used a lot.
1853 /// This module contains all the defined non-keyword `Symbol`s.
1855 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1856 /// For example `sym::rustfmt` or `sym::u8`.
1859 use std::convert::TryInto;
1862 pub use super::sym_generated::*;
1864 // Used from a macro in `librustc_feature/accepted.rs`
1865 pub use super::kw::MacroRules as macro_rules;
1867 /// Get the symbol for an integer.
1869 /// The first few non-negative integers each have a static symbol and therefore
1871 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1872 if let Result::Ok(idx) = n.try_into() {
1874 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
1877 Symbol::intern(&n.to_string())
1882 fn is_special(self) -> bool {
1883 self <= kw::Underscore
1886 fn is_used_keyword_always(self) -> bool {
1887 self >= kw::As && self <= kw::While
1890 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1891 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
1894 fn is_unused_keyword_always(self) -> bool {
1895 self >= kw::Abstract && self <= kw::Yield
1898 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1899 self == kw::Try && edition() >= Edition::Edition2018
1902 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
1904 || self.is_used_keyword_always()
1905 || self.is_unused_keyword_always()
1906 || self.is_used_keyword_conditional(edition)
1907 || self.is_unused_keyword_conditional(edition)
1910 /// A keyword or reserved identifier that can be used as a path segment.
1911 pub fn is_path_segment_keyword(self) -> bool {
1913 || self == kw::SelfLower
1914 || self == kw::SelfUpper
1915 || self == kw::Crate
1916 || self == kw::PathRoot
1917 || self == kw::DollarCrate
1920 /// Returns `true` if the symbol is `true` or `false`.
1921 pub fn is_bool_lit(self) -> bool {
1922 self == kw::True || self == kw::False
1925 /// Returns `true` if this symbol can be a raw identifier.
1926 pub fn can_be_raw(self) -> bool {
1927 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
1932 // Returns `true` for reserved identifiers used internally for elided lifetimes,
1933 // unnamed method parameters, crate root module, error recovery etc.
1934 pub fn is_special(self) -> bool {
1935 self.name.is_special()
1938 /// Returns `true` if the token is a keyword used in the language.
1939 pub fn is_used_keyword(self) -> bool {
1940 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1941 self.name.is_used_keyword_always()
1942 || self.name.is_used_keyword_conditional(|| self.span.edition())
1945 /// Returns `true` if the token is a keyword reserved for possible future use.
1946 pub fn is_unused_keyword(self) -> bool {
1947 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1948 self.name.is_unused_keyword_always()
1949 || self.name.is_unused_keyword_conditional(|| self.span.edition())
1952 /// Returns `true` if the token is either a special identifier or a keyword.
1953 pub fn is_reserved(self) -> bool {
1954 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1955 self.name.is_reserved(|| self.span.edition())
1958 /// A keyword or reserved identifier that can be used as a path segment.
1959 pub fn is_path_segment_keyword(self) -> bool {
1960 self.name.is_path_segment_keyword()
1963 /// We see this identifier in a normal identifier position, like variable name or a type.
1964 /// How was it written originally? Did it use the raw form? Let's try to guess.
1965 pub fn is_raw_guess(self) -> bool {
1966 self.name.can_be_raw() && self.is_reserved()