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",
107 // Pre-interned symbols that can be referred to with `rustc_span::sym::*`.
109 // The symbol is the stringified identifier unless otherwise specified, in
110 // which case the name should mention the non-identifier punctuation.
111 // E.g. `sym::proc_dash_macro` represents "proc-macro", and it shouldn't be
112 // called `sym::proc_macro` because then it's easy to mistakenly think it
113 // represents "proc_macro".
115 // As well as the symbols listed, there are symbols for the strings
116 // "0", "1", ..., "9", which are accessible via `sym::integer`.
118 // The proc macro will abort if symbols are not in alphabetical order (as
119 // defined by `impl Ord for str`) or if any symbols are duplicated. Vim
120 // users can sort the list by selecting it and executing the command
121 // `:'<,'>!LC_ALL=C sort`.
123 // There is currently no checking that all symbols are used; that would be
245 ProceduralMasqueradeDummyType,
270 SubdiagnosticMessage,
300 aarch64_target_feature,
301 aarch64_ver_target_feature,
305 abi_c_cmse_nonsecure_call,
307 abi_msp430_interrupt,
321 advanced_slice_patterns,
337 allow_internal_unsafe,
338 allow_internal_unstable,
346 arbitrary_enum_discriminant,
347 arbitrary_self_types,
359 asm_experimental_arch,
367 assert_receiver_is_total_eq,
371 associated_const_equality,
373 associated_type_bounds,
374 associated_type_defaults,
387 augmented_assignments,
389 automatically_derived,
391 avx512_target_feature,
399 bind_by_move_pattern_guards,
411 borrowck_graphviz_format,
412 borrowck_graphviz_postflow,
413 borrowck_graphviz_preflow,
418 braced_empty_structs,
430 capture_disjoint_fields,
447 cfg_target_has_atomic,
448 cfg_target_has_atomic_equal_alignment,
449 cfg_target_has_atomic_load_store,
450 cfg_target_thread_local,
462 closure_to_fn_coercion,
463 closure_track_caller,
467 cmpxchg16b_target_feature,
468 cmse_nonsecure_entry,
475 compare_exchange_weak,
485 conservative_impl_trait,
489 const_compare_raw_pointers,
494 const_eval_select_ct,
495 const_evaluatable_checked,
498 const_fn_floating_point_arithmetic,
499 const_fn_fn_ptr_basics,
500 const_fn_trait_bound,
506 const_generic_defaults,
508 const_generics_defaults,
511 const_in_array_repeat_expressions,
518 const_precise_live_drops,
520 const_raw_ptr_to_usize_cast,
523 const_trait_bound_opt_out,
540 core_panic_2015_macro,
551 crate_visibility_modifier,
552 crt_dash_static: "crt-static",
561 custom_inner_attributes,
562 custom_test_frameworks,
569 debug_assert_eq_macro,
571 debug_assert_ne_macro,
574 debug_struct_fields_finish,
577 debug_tuple_fields_finish,
582 default_alloc_error_handler,
583 default_lib_allocator,
584 default_method_body_is_const,
585 default_type_parameter_fallback,
587 delay_span_bug_from_inside_query,
591 deprecated_suggestion,
599 destructuring_assignment,
620 document_private_items,
622 dotdot_in_tuple_patterns,
623 dotdoteq_in_patterns,
631 dropck_parametricity,
642 emit_enum_variant_arg,
654 ermsb_target_feature,
658 exclusive_range_pattern,
659 exhaustive_integer_patterns,
668 explicit_generic_args_with_impl_trait,
671 extended_key_value_attributes,
672 extern_absolute_paths,
673 extern_crate_item_prelude,
696 field_init_shorthand,
703 float_to_int_unchecked,
736 from_size_align_unchecked,
753 generic_associated_types,
754 generic_associated_types_extended,
762 half_open_range_patterns,
764 hexagon_target_feature,
766 homogeneous_aggregate,
783 if_while_or_patterns,
785 impl_header_lifetime_elision,
788 impl_trait_in_bindings,
798 inclusive_range_syntax,
801 infer_outlives_requirements,
802 infer_static_outlives_requirements,
803 inherent_associated_types,
817 irrefutable_let_patterns,
821 issue_5723_bootstrap,
822 issue_tracker_base_url,
837 lazy_normalization_consts,
852 link_llvm_intrinsics,
873 macro_at_most_once_rep,
874 macro_attributes_in_derive_output,
877 macro_lifetime_matcher,
878 macro_literal_matcher,
891 match_beginning_vert,
892 match_default_bindings,
922 min_type_alias_impl_trait,
933 more_qualified_paths,
935 movbe_target_feature,
947 native_link_modifiers,
948 native_link_modifiers_as_needed,
949 native_link_modifiers_bundle,
950 native_link_modifiers_verbatim,
951 native_link_modifiers_whole_archive,
990 non_exhaustive_omitted_patterns_lint,
1002 object_safe_for_dispatch,
1005 omit_gdb_pretty_printer_section,
1014 optin_builtin_traits,
1023 overlapping_marker_traits,
1035 panic_implementation,
1050 pattern_parentheses,
1053 platform_intrinsics,
1062 post_dash_lto: "post-lto",
1063 powerpc_target_feature,
1068 pre_dash_lto: "pre-lto",
1069 precise_pointer_size_matching,
1073 prefetch_read_instruction,
1074 prefetch_write_data,
1075 prefetch_write_instruction,
1083 proc_dash_macro: "proc-macro",
1085 proc_macro_attribute,
1086 proc_macro_def_site,
1091 proc_macro_internals,
1093 proc_macro_non_items,
1094 proc_macro_path_invoc,
1103 ptr_offset_from_unsigned,
1111 quad_precision_float,
1114 range_inclusive_new,
1119 re_rebalance_coherence,
1122 read_enum_variant_arg,
1130 reexport_test_harness_main,
1131 ref_unwind_safe_trait,
1148 relaxed_struct_unsize,
1164 riscv_target_feature,
1183 rust_eh_catch_typeinfo,
1184 rust_eh_personality,
1185 rust_eh_register_frames,
1186 rust_eh_unregister_frames,
1190 rustc_allocator_nounwind,
1191 rustc_allow_const_fn_unstable,
1192 rustc_allow_incoherent_impl,
1195 rustc_builtin_macro,
1196 rustc_capture_analysis,
1198 rustc_coherence_is_core,
1200 rustc_const_unstable,
1201 rustc_conversion_suggestion,
1203 rustc_diagnostic_item,
1204 rustc_diagnostic_macros,
1206 rustc_do_not_const_check,
1208 rustc_dump_env_program_clauses,
1209 rustc_dump_program_clauses,
1210 rustc_dump_user_substs,
1213 rustc_evaluate_where_clauses,
1214 rustc_expected_cgu_reuse,
1215 rustc_has_incoherent_inherent_impls,
1216 rustc_if_this_changed,
1217 rustc_inherit_overflow_checks,
1218 rustc_insignificant_dtor,
1220 rustc_layout_scalar_valid_range_end,
1221 rustc_layout_scalar_valid_range_start,
1222 rustc_legacy_const_generics,
1223 rustc_lint_diagnostics,
1224 rustc_lint_query_instability,
1225 rustc_macro_transparency,
1228 rustc_must_implement_one_of,
1229 rustc_nonnull_optimization_guaranteed,
1230 rustc_object_lifetime_default,
1231 rustc_on_unimplemented,
1234 rustc_partition_codegened,
1235 rustc_partition_reused,
1236 rustc_pass_by_value,
1238 rustc_peek_definite_init,
1239 rustc_peek_liveness,
1240 rustc_peek_maybe_init,
1241 rustc_peek_maybe_uninit,
1242 rustc_polymorphize_error,
1244 rustc_proc_macro_decls,
1247 rustc_reservation_impl,
1249 rustc_skip_array_during_method_dispatch,
1250 rustc_specialization_trait,
1252 rustc_std_internal_symbol,
1253 rustc_strict_coherence,
1256 rustc_then_this_would_need,
1257 rustc_trivial_field_reads,
1258 rustc_unsafe_specialization_marker,
1263 rvalue_static_promotion,
1314 simd_reduce_add_ordered,
1315 simd_reduce_add_unordered,
1320 simd_reduce_max_nanless,
1322 simd_reduce_min_nanless,
1323 simd_reduce_mul_ordered,
1324 simd_reduce_mul_unordered,
1329 simd_saturating_add,
1330 simd_saturating_sub,
1333 simd_select_bitmask,
1361 sse4a_target_feature,
1373 std_panic_2015_macro,
1376 stmt_expr_attributes,
1377 stop_after_dataflow,
1380 str_split_whitespace,
1387 struct_field_attributes,
1410 target_has_atomic_equal_alignment,
1411 target_has_atomic_load_store,
1413 target_pointer_width,
1414 target_target_vendor,
1415 target_thread_local,
1421 termination_trait_test,
1424 test_accepted_feature,
1426 test_removed_feature,
1434 thumb_mode: "thumb-mode",
1462 type_alias_enum_variants,
1463 type_alias_impl_trait,
1465 type_changing_struct_update,
1475 unaligned_volatile_load,
1476 unaligned_volatile_store,
1485 underscore_const_names,
1487 underscore_lifetimes,
1489 unimplemented_macro,
1491 universal_impl_trait,
1498 unreachable_2015_macro,
1500 unreachable_2021_macro,
1502 unreachable_display,
1504 unrestricted_attribute_tokens,
1505 unsafe_block_in_unsafe_fn,
1507 unsafe_no_drop_flag,
1508 unsafe_pin_internals,
1512 unsized_tuple_coercion,
1516 unused_qualifications,
1542 visible_private_types,
1544 volatile_copy_memory,
1545 volatile_copy_nonoverlapping_memory,
1547 volatile_set_memory,
1554 wasm_target_feature,
1559 with_negative_coherence,
1571 yeet_desugar_details,
1578 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1586 /// Constructs a new identifier from a symbol and a span.
1587 pub const fn new(name: Symbol, span: Span) -> Ident {
1588 Ident { name, span }
1591 /// Constructs a new identifier with a dummy span.
1593 pub const fn with_dummy_span(name: Symbol) -> Ident {
1594 Ident::new(name, DUMMY_SP)
1598 pub fn empty() -> Ident {
1599 Ident::with_dummy_span(kw::Empty)
1602 /// Maps a string to an identifier with a dummy span.
1603 pub fn from_str(string: &str) -> Ident {
1604 Ident::with_dummy_span(Symbol::intern(string))
1607 /// Maps a string and a span to an identifier.
1608 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1609 Ident::new(Symbol::intern(string), span)
1612 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1613 pub fn with_span_pos(self, span: Span) -> Ident {
1614 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1617 pub fn without_first_quote(self) -> Ident {
1618 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1621 /// "Normalize" ident for use in comparisons using "item hygiene".
1622 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1623 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1624 /// different macro 2.0 macros.
1625 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1626 pub fn normalize_to_macros_2_0(self) -> Ident {
1627 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1630 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1631 /// Identifiers with same string value become same if they came from the same non-transparent
1632 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1633 /// non-transparent macros.
1634 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1635 pub fn normalize_to_macro_rules(self) -> Ident {
1636 Ident::new(self.name, self.span.normalize_to_macro_rules())
1639 /// Access the underlying string. This is a slowish operation because it
1640 /// requires locking the symbol interner.
1642 /// Note that the lifetime of the return value is a lie. See
1643 /// `Symbol::as_str()` for details.
1644 pub fn as_str(&self) -> &str {
1649 impl PartialEq for Ident {
1650 fn eq(&self, rhs: &Self) -> bool {
1651 self.name == rhs.name && self.span.eq_ctxt(rhs.span)
1655 impl Hash for Ident {
1656 fn hash<H: Hasher>(&self, state: &mut H) {
1657 self.name.hash(state);
1658 self.span.ctxt().hash(state);
1662 impl fmt::Debug for Ident {
1663 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1664 fmt::Display::fmt(self, f)?;
1665 fmt::Debug::fmt(&self.span.ctxt(), f)
1669 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1670 /// to printing the original identifier token written in source code (`token_to_string`),
1671 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1672 impl fmt::Display for Ident {
1673 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1674 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1678 /// This is the most general way to print identifiers.
1679 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1680 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1681 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1682 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1683 /// hygiene data, most importantly name of the crate it refers to.
1684 /// As a result we print `$crate` as `crate` if it refers to the local crate
1685 /// and as `::other_crate_name` if it refers to some other crate.
1686 /// Note, that this is only done if the ident token is printed from inside of AST pretty-printing,
1687 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1688 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1689 /// done for a token stream or a single token.
1690 pub struct IdentPrinter {
1693 /// Span used for retrieving the crate name to which `$crate` refers to,
1694 /// if this field is `None` then the `$crate` conversion doesn't happen.
1695 convert_dollar_crate: Option<Span>,
1699 /// The most general `IdentPrinter` constructor. Do not use this.
1700 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1701 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1704 /// This implementation is supposed to be used when printing identifiers
1705 /// as a part of pretty-printing for larger AST pieces.
1706 /// Do not use this either.
1707 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1708 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1712 impl fmt::Display for IdentPrinter {
1713 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1716 } else if self.symbol == kw::DollarCrate {
1717 if let Some(span) = self.convert_dollar_crate {
1718 let converted = span.ctxt().dollar_crate_name();
1719 if !converted.is_path_segment_keyword() {
1722 return fmt::Display::fmt(&converted, f);
1725 fmt::Display::fmt(&self.symbol, f)
1729 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1731 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1732 // `ModernIdent` struct and use that as well.
1733 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1734 pub struct MacroRulesNormalizedIdent(Ident);
1736 impl MacroRulesNormalizedIdent {
1737 pub fn new(ident: Ident) -> Self {
1738 Self(ident.normalize_to_macro_rules())
1742 impl fmt::Debug for MacroRulesNormalizedIdent {
1743 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1744 fmt::Debug::fmt(&self.0, f)
1748 impl fmt::Display for MacroRulesNormalizedIdent {
1749 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1750 fmt::Display::fmt(&self.0, f)
1754 /// An interned string.
1756 /// Internally, a `Symbol` is implemented as an index, and all operations
1757 /// (including hashing, equality, and ordering) operate on that index. The use
1758 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1759 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1761 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1762 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1763 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1764 pub struct Symbol(SymbolIndex);
1766 rustc_index::newtype_index! {
1767 struct SymbolIndex { .. }
1771 const fn new(n: u32) -> Self {
1772 Symbol(SymbolIndex::from_u32(n))
1775 /// Maps a string to its interned representation.
1776 pub fn intern(string: &str) -> Self {
1777 with_session_globals(|session_globals| session_globals.symbol_interner.intern(string))
1780 /// Access the underlying string. This is a slowish operation because it
1781 /// requires locking the symbol interner.
1783 /// Note that the lifetime of the return value is a lie. It's not the same
1784 /// as `&self`, but actually tied to the lifetime of the underlying
1785 /// interner. Interners are long-lived, and there are very few of them, and
1786 /// this function is typically used for short-lived things, so in practice
1787 /// it works out ok.
1788 pub fn as_str(&self) -> &str {
1789 with_session_globals(|session_globals| unsafe {
1790 std::mem::transmute::<&str, &str>(session_globals.symbol_interner.get(*self))
1794 pub fn as_u32(self) -> u32 {
1798 pub fn is_empty(self) -> bool {
1802 /// This method is supposed to be used in error messages, so it's expected to be
1803 /// identical to printing the original identifier token written in source code
1804 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1805 /// or edition, so we have to guess the rawness using the global edition.
1806 pub fn to_ident_string(self) -> String {
1807 Ident::with_dummy_span(self).to_string()
1811 impl fmt::Debug for Symbol {
1812 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1813 fmt::Debug::fmt(self.as_str(), f)
1817 impl fmt::Display for Symbol {
1818 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1819 fmt::Display::fmt(self.as_str(), f)
1823 impl<S: Encoder> Encodable<S> for Symbol {
1824 fn encode(&self, s: &mut S) {
1825 s.emit_str(self.as_str());
1829 impl<D: Decoder> Decodable<D> for Symbol {
1831 fn decode(d: &mut D) -> Symbol {
1832 Symbol::intern(&d.read_str())
1836 impl<CTX> HashStable<CTX> for Symbol {
1838 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1839 self.as_str().hash_stable(hcx, hasher);
1843 impl<CTX> ToStableHashKey<CTX> for Symbol {
1844 type KeyType = String;
1846 fn to_stable_hash_key(&self, _: &CTX) -> String {
1847 self.as_str().to_string()
1852 pub(crate) struct Interner(Lock<InternerInner>);
1854 // The `&'static str`s in this type actually point into the arena.
1856 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1857 // found that to regress performance up to 2% in some cases. This might be
1858 // revisited after further improvements to `indexmap`.
1860 // This type is private to prevent accidentally constructing more than one
1861 // `Interner` on the same thread, which makes it easy to mix up `Symbol`s
1862 // between `Interner`s.
1864 struct InternerInner {
1865 arena: DroplessArena,
1866 names: FxHashMap<&'static str, Symbol>,
1867 strings: Vec<&'static str>,
1871 fn prefill(init: &[&'static str]) -> Self {
1872 Interner(Lock::new(InternerInner {
1873 strings: init.into(),
1874 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1875 ..Default::default()
1880 fn intern(&self, string: &str) -> Symbol {
1881 let mut inner = self.0.lock();
1882 if let Some(&name) = inner.names.get(string) {
1886 let name = Symbol::new(inner.strings.len() as u32);
1888 // SAFETY: we convert from `&str` to `&[u8]`, clone it into the arena,
1889 // and immediately convert the clone back to `&[u8], all because there
1890 // is no `inner.arena.alloc_str()` method. This is clearly safe.
1892 unsafe { str::from_utf8_unchecked(inner.arena.alloc_slice(string.as_bytes())) };
1894 // SAFETY: we can extend the arena allocation to `'static` because we
1895 // only access these while the arena is still alive.
1896 let string: &'static str = unsafe { &*(string as *const str) };
1897 inner.strings.push(string);
1899 // This second hash table lookup can be avoided by using `RawEntryMut`,
1900 // but this code path isn't hot enough for it to be worth it. See
1901 // #91445 for details.
1902 inner.names.insert(string, name);
1906 // Get the symbol as a string. `Symbol::as_str()` should be used in
1907 // preference to this function.
1908 fn get(&self, symbol: Symbol) -> &str {
1909 self.0.lock().strings[symbol.0.as_usize()]
1913 // This module has a very short name because it's used a lot.
1914 /// This module contains all the defined keyword `Symbol`s.
1916 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1917 /// For example `kw::Loop` or `kw::Break`.
1919 pub use super::kw_generated::*;
1922 // This module has a very short name because it's used a lot.
1923 /// This module contains all the defined non-keyword `Symbol`s.
1925 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1926 /// For example `sym::rustfmt` or `sym::u8`.
1929 use std::convert::TryInto;
1932 pub use super::sym_generated::*;
1934 // Used from a macro in `librustc_feature/accepted.rs`
1935 pub use super::kw::MacroRules as macro_rules;
1937 /// Get the symbol for an integer.
1939 /// The first few non-negative integers each have a static symbol and therefore
1941 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1942 if let Result::Ok(idx) = n.try_into() {
1944 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
1947 Symbol::intern(&n.to_string())
1952 fn is_special(self) -> bool {
1953 self <= kw::Underscore
1956 fn is_used_keyword_always(self) -> bool {
1957 self >= kw::As && self <= kw::While
1960 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1961 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
1964 fn is_unused_keyword_always(self) -> bool {
1965 self >= kw::Abstract && self <= kw::Yield
1968 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1969 self == kw::Try && edition() >= Edition::Edition2018
1972 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
1974 || self.is_used_keyword_always()
1975 || self.is_unused_keyword_always()
1976 || self.is_used_keyword_conditional(edition)
1977 || self.is_unused_keyword_conditional(edition)
1980 /// A keyword or reserved identifier that can be used as a path segment.
1981 pub fn is_path_segment_keyword(self) -> bool {
1983 || self == kw::SelfLower
1984 || self == kw::SelfUpper
1985 || self == kw::Crate
1986 || self == kw::PathRoot
1987 || self == kw::DollarCrate
1990 /// Returns `true` if the symbol is `true` or `false`.
1991 pub fn is_bool_lit(self) -> bool {
1992 self == kw::True || self == kw::False
1995 /// Returns `true` if this symbol can be a raw identifier.
1996 pub fn can_be_raw(self) -> bool {
1997 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
2002 // Returns `true` for reserved identifiers used internally for elided lifetimes,
2003 // unnamed method parameters, crate root module, error recovery etc.
2004 pub fn is_special(self) -> bool {
2005 self.name.is_special()
2008 /// Returns `true` if the token is a keyword used in the language.
2009 pub fn is_used_keyword(self) -> bool {
2010 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2011 self.name.is_used_keyword_always()
2012 || self.name.is_used_keyword_conditional(|| self.span.edition())
2015 /// Returns `true` if the token is a keyword reserved for possible future use.
2016 pub fn is_unused_keyword(self) -> bool {
2017 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2018 self.name.is_unused_keyword_always()
2019 || self.name.is_unused_keyword_conditional(|| self.span.edition())
2022 /// Returns `true` if the token is either a special identifier or a keyword.
2023 pub fn is_reserved(self) -> bool {
2024 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2025 self.name.is_reserved(|| self.span.edition())
2028 /// A keyword or reserved identifier that can be used as a path segment.
2029 pub fn is_path_segment_keyword(self) -> bool {
2030 self.name.is_path_segment_keyword()
2033 /// We see this identifier in a normal identifier position, like variable name or a type.
2034 /// How was it written originally? Did it use the raw form? Let's try to guess.
2035 pub fn is_raw_guess(self) -> bool {
2036 self.name.can_be_raw() && self.is_reserved()