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
255 ProceduralMasqueradeDummyType,
281 SubdiagnosticMessage,
311 aarch64_target_feature,
312 aarch64_ver_target_feature,
316 abi_c_cmse_nonsecure_call,
318 abi_msp430_interrupt,
332 advanced_slice_patterns,
348 allow_internal_unsafe,
349 allow_internal_unstable,
355 anonymous_lifetime_in_impl_trait,
358 arbitrary_enum_discriminant,
359 arbitrary_self_types,
371 asm_experimental_arch,
379 assert_receiver_is_total_eq,
383 associated_const_equality,
385 associated_type_bounds,
386 associated_type_defaults,
399 augmented_assignments,
401 automatically_derived,
403 avx512_target_feature,
411 bind_by_move_pattern_guards,
423 borrowck_graphviz_format,
424 borrowck_graphviz_postflow,
425 borrowck_graphviz_preflow,
430 braced_empty_structs,
442 capture_disjoint_fields,
459 cfg_target_has_atomic,
460 cfg_target_has_atomic_equal_alignment,
461 cfg_target_has_atomic_load_store,
462 cfg_target_thread_local,
474 closure_lifetime_binder,
475 closure_to_fn_coercion,
476 closure_track_caller,
480 cmpxchg16b_target_feature,
481 cmse_nonsecure_entry,
488 compare_exchange_weak,
498 conservative_impl_trait,
502 const_compare_raw_pointers,
507 const_eval_select_ct,
508 const_evaluatable_checked,
511 const_fn_floating_point_arithmetic,
512 const_fn_fn_ptr_basics,
513 const_fn_trait_bound,
519 const_generic_defaults,
521 const_generics_defaults,
524 const_in_array_repeat_expressions,
531 const_precise_live_drops,
533 const_raw_ptr_to_usize_cast,
536 const_trait_bound_opt_out,
553 core_panic_2015_macro,
564 crate_visibility_modifier,
565 crt_dash_static: "crt-static",
574 custom_inner_attributes,
575 custom_test_frameworks,
582 debug_assert_eq_macro,
584 debug_assert_ne_macro,
587 debug_struct_fields_finish,
590 debug_tuple_fields_finish,
595 default_alloc_error_handler,
596 default_lib_allocator,
597 default_method_body_is_const,
598 default_type_parameter_fallback,
600 delay_span_bug_from_inside_query,
604 deprecated_suggestion,
612 destructuring_assignment,
633 document_private_items,
635 dotdot_in_tuple_patterns,
636 dotdoteq_in_patterns,
644 dropck_parametricity,
655 emit_enum_variant_arg,
667 ermsb_target_feature,
671 exclusive_range_pattern,
672 exhaustive_integer_patterns,
681 explicit_generic_args_with_impl_trait,
684 extended_key_value_attributes,
685 extern_absolute_paths,
686 extern_crate_item_prelude,
710 field_init_shorthand,
717 float_to_int_unchecked,
750 from_size_align_unchecked,
767 generic_associated_types,
768 generic_associated_types_extended,
776 half_open_range_patterns,
778 hexagon_target_feature,
780 homogeneous_aggregate,
797 if_while_or_patterns,
799 impl_header_lifetime_elision,
802 impl_trait_in_bindings,
814 inclusive_range_syntax,
817 infer_outlives_requirements,
818 infer_static_outlives_requirements,
819 inherent_associated_types,
833 irrefutable_let_patterns,
837 issue_5723_bootstrap,
838 issue_tracker_base_url,
853 lazy_normalization_consts,
868 link_llvm_intrinsics,
889 macro_at_most_once_rep,
890 macro_attributes_in_derive_output,
893 macro_lifetime_matcher,
894 macro_literal_matcher,
907 match_beginning_vert,
908 match_default_bindings,
938 min_type_alias_impl_trait,
949 more_qualified_paths,
951 movbe_target_feature,
963 native_link_modifiers,
964 native_link_modifiers_as_needed,
965 native_link_modifiers_bundle,
966 native_link_modifiers_verbatim,
967 native_link_modifiers_whole_archive,
1005 non_exhaustive_omitted_patterns_lint,
1017 object_safe_for_dispatch,
1020 omit_gdb_pretty_printer_section,
1029 optin_builtin_traits,
1038 overlapping_marker_traits,
1050 panic_implementation,
1065 pattern_parentheses,
1068 platform_intrinsics,
1077 post_dash_lto: "post-lto",
1078 powerpc_target_feature,
1083 pre_dash_lto: "pre-lto",
1084 precise_pointer_size_matching,
1088 prefetch_read_instruction,
1089 prefetch_write_data,
1090 prefetch_write_instruction,
1098 proc_dash_macro: "proc-macro",
1100 proc_macro_attribute,
1101 proc_macro_def_site,
1106 proc_macro_internals,
1108 proc_macro_non_items,
1109 proc_macro_path_invoc,
1118 ptr_offset_from_unsigned,
1126 quad_precision_float,
1129 range_inclusive_new,
1134 re_rebalance_coherence,
1137 read_enum_variant_arg,
1145 reexport_test_harness_main,
1146 ref_unwind_safe_trait,
1163 relaxed_struct_unsize,
1178 riscv_target_feature,
1197 rust_eh_catch_typeinfo,
1198 rust_eh_personality,
1199 rust_eh_register_frames,
1200 rust_eh_unregister_frames,
1204 rustc_allocator_nounwind,
1205 rustc_allocator_zeroed,
1206 rustc_allow_const_fn_unstable,
1207 rustc_allow_incoherent_impl,
1208 rustc_allowed_through_unstable_modules,
1211 rustc_builtin_macro,
1212 rustc_capture_analysis,
1214 rustc_coherence_is_core,
1216 rustc_const_unstable,
1217 rustc_conversion_suggestion,
1220 rustc_diagnostic_item,
1221 rustc_diagnostic_macros,
1223 rustc_do_not_const_check,
1225 rustc_dump_env_program_clauses,
1226 rustc_dump_program_clauses,
1227 rustc_dump_user_substs,
1230 rustc_evaluate_where_clauses,
1231 rustc_expected_cgu_reuse,
1232 rustc_has_incoherent_inherent_impls,
1233 rustc_if_this_changed,
1234 rustc_inherit_overflow_checks,
1235 rustc_insignificant_dtor,
1237 rustc_layout_scalar_valid_range_end,
1238 rustc_layout_scalar_valid_range_start,
1239 rustc_legacy_const_generics,
1240 rustc_lint_diagnostics,
1241 rustc_lint_query_instability,
1242 rustc_macro_transparency,
1245 rustc_must_implement_one_of,
1246 rustc_nonnull_optimization_guaranteed,
1247 rustc_object_lifetime_default,
1248 rustc_on_unimplemented,
1251 rustc_partition_codegened,
1252 rustc_partition_reused,
1253 rustc_pass_by_value,
1255 rustc_peek_definite_init,
1256 rustc_peek_liveness,
1257 rustc_peek_maybe_init,
1258 rustc_peek_maybe_uninit,
1259 rustc_polymorphize_error,
1261 rustc_proc_macro_decls,
1265 rustc_reservation_impl,
1267 rustc_skip_array_during_method_dispatch,
1268 rustc_specialization_trait,
1270 rustc_std_internal_symbol,
1271 rustc_strict_coherence,
1274 rustc_then_this_would_need,
1275 rustc_trivial_field_reads,
1276 rustc_unsafe_specialization_marker,
1281 rvalue_static_promotion,
1333 simd_reduce_add_ordered,
1334 simd_reduce_add_unordered,
1339 simd_reduce_max_nanless,
1341 simd_reduce_min_nanless,
1342 simd_reduce_mul_ordered,
1343 simd_reduce_mul_unordered,
1348 simd_saturating_add,
1349 simd_saturating_sub,
1352 simd_select_bitmask,
1380 sse4a_target_feature,
1392 std_panic_2015_macro,
1395 stmt_expr_attributes,
1396 stop_after_dataflow,
1399 str_split_whitespace,
1406 struct_field_attributes,
1429 target_has_atomic_equal_alignment,
1430 target_has_atomic_load_store,
1432 target_pointer_width,
1433 target_target_vendor,
1434 target_thread_local,
1440 termination_trait_test,
1443 test_accepted_feature,
1445 test_removed_feature,
1453 thumb_mode: "thumb-mode",
1482 type_alias_enum_variants,
1483 type_alias_impl_trait,
1485 type_changing_struct_update,
1495 unaligned_volatile_load,
1496 unaligned_volatile_store,
1505 underscore_const_names,
1507 underscore_lifetimes,
1509 unimplemented_macro,
1511 universal_impl_trait,
1518 unreachable_2015_macro,
1520 unreachable_2021_macro,
1522 unreachable_display,
1524 unrestricted_attribute_tokens,
1525 unsafe_block_in_unsafe_fn,
1527 unsafe_no_drop_flag,
1528 unsafe_pin_internals,
1532 unsized_tuple_coercion,
1534 unstable_location_reason_default: "this crate is being loaded from the sysroot, an \
1535 unstable location; did you mean to load this crate \
1536 from crates.io via `Cargo.toml` instead?",
1539 unused_qualifications,
1566 visible_private_types,
1568 volatile_copy_memory,
1569 volatile_copy_nonoverlapping_memory,
1571 volatile_set_memory,
1580 wasm_target_feature,
1585 with_negative_coherence,
1597 yeet_desugar_details,
1604 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1612 /// Constructs a new identifier from a symbol and a span.
1613 pub const fn new(name: Symbol, span: Span) -> Ident {
1614 Ident { name, span }
1617 /// Constructs a new identifier with a dummy span.
1619 pub const fn with_dummy_span(name: Symbol) -> Ident {
1620 Ident::new(name, DUMMY_SP)
1624 pub fn empty() -> Ident {
1625 Ident::with_dummy_span(kw::Empty)
1628 /// Maps a string to an identifier with a dummy span.
1629 pub fn from_str(string: &str) -> Ident {
1630 Ident::with_dummy_span(Symbol::intern(string))
1633 /// Maps a string and a span to an identifier.
1634 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1635 Ident::new(Symbol::intern(string), span)
1638 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1639 pub fn with_span_pos(self, span: Span) -> Ident {
1640 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1643 pub fn without_first_quote(self) -> Ident {
1644 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1647 /// "Normalize" ident for use in comparisons using "item hygiene".
1648 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1649 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1650 /// different macro 2.0 macros.
1651 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1652 pub fn normalize_to_macros_2_0(self) -> Ident {
1653 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1656 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1657 /// Identifiers with same string value become same if they came from the same non-transparent
1658 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1659 /// non-transparent macros.
1660 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1661 pub fn normalize_to_macro_rules(self) -> Ident {
1662 Ident::new(self.name, self.span.normalize_to_macro_rules())
1665 /// Access the underlying string. This is a slowish operation because it
1666 /// requires locking the symbol interner.
1668 /// Note that the lifetime of the return value is a lie. See
1669 /// `Symbol::as_str()` for details.
1670 pub fn as_str(&self) -> &str {
1675 impl PartialEq for Ident {
1676 fn eq(&self, rhs: &Self) -> bool {
1677 self.name == rhs.name && self.span.eq_ctxt(rhs.span)
1681 impl Hash for Ident {
1682 fn hash<H: Hasher>(&self, state: &mut H) {
1683 self.name.hash(state);
1684 self.span.ctxt().hash(state);
1688 impl fmt::Debug for Ident {
1689 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1690 fmt::Display::fmt(self, f)?;
1691 fmt::Debug::fmt(&self.span.ctxt(), f)
1695 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1696 /// to printing the original identifier token written in source code (`token_to_string`),
1697 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1698 impl fmt::Display for Ident {
1699 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1700 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1704 /// This is the most general way to print identifiers.
1705 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1706 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1707 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1708 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1709 /// hygiene data, most importantly name of the crate it refers to.
1710 /// As a result we print `$crate` as `crate` if it refers to the local crate
1711 /// and as `::other_crate_name` if it refers to some other crate.
1712 /// Note, that this is only done if the ident token is printed from inside of AST pretty-printing,
1713 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1714 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1715 /// done for a token stream or a single token.
1716 pub struct IdentPrinter {
1719 /// Span used for retrieving the crate name to which `$crate` refers to,
1720 /// if this field is `None` then the `$crate` conversion doesn't happen.
1721 convert_dollar_crate: Option<Span>,
1725 /// The most general `IdentPrinter` constructor. Do not use this.
1726 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1727 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1730 /// This implementation is supposed to be used when printing identifiers
1731 /// as a part of pretty-printing for larger AST pieces.
1732 /// Do not use this either.
1733 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1734 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1738 impl fmt::Display for IdentPrinter {
1739 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1742 } else if self.symbol == kw::DollarCrate {
1743 if let Some(span) = self.convert_dollar_crate {
1744 let converted = span.ctxt().dollar_crate_name();
1745 if !converted.is_path_segment_keyword() {
1748 return fmt::Display::fmt(&converted, f);
1751 fmt::Display::fmt(&self.symbol, f)
1755 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1757 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1758 // `ModernIdent` struct and use that as well.
1759 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1760 pub struct MacroRulesNormalizedIdent(Ident);
1762 impl MacroRulesNormalizedIdent {
1763 pub fn new(ident: Ident) -> Self {
1764 Self(ident.normalize_to_macro_rules())
1768 impl fmt::Debug for MacroRulesNormalizedIdent {
1769 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1770 fmt::Debug::fmt(&self.0, f)
1774 impl fmt::Display for MacroRulesNormalizedIdent {
1775 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1776 fmt::Display::fmt(&self.0, f)
1780 /// An interned string.
1782 /// Internally, a `Symbol` is implemented as an index, and all operations
1783 /// (including hashing, equality, and ordering) operate on that index. The use
1784 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1785 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1787 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1788 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1789 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1790 pub struct Symbol(SymbolIndex);
1792 rustc_index::newtype_index! {
1793 struct SymbolIndex { .. }
1797 const fn new(n: u32) -> Self {
1798 Symbol(SymbolIndex::from_u32(n))
1801 /// Maps a string to its interned representation.
1802 pub fn intern(string: &str) -> Self {
1803 with_session_globals(|session_globals| session_globals.symbol_interner.intern(string))
1806 /// Access the underlying string. This is a slowish operation because it
1807 /// requires locking the symbol interner.
1809 /// Note that the lifetime of the return value is a lie. It's not the same
1810 /// as `&self`, but actually tied to the lifetime of the underlying
1811 /// interner. Interners are long-lived, and there are very few of them, and
1812 /// this function is typically used for short-lived things, so in practice
1813 /// it works out ok.
1814 pub fn as_str(&self) -> &str {
1815 with_session_globals(|session_globals| unsafe {
1816 std::mem::transmute::<&str, &str>(session_globals.symbol_interner.get(*self))
1820 pub fn as_u32(self) -> u32 {
1824 pub fn is_empty(self) -> bool {
1828 /// This method is supposed to be used in error messages, so it's expected to be
1829 /// identical to printing the original identifier token written in source code
1830 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1831 /// or edition, so we have to guess the rawness using the global edition.
1832 pub fn to_ident_string(self) -> String {
1833 Ident::with_dummy_span(self).to_string()
1837 impl fmt::Debug for Symbol {
1838 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1839 fmt::Debug::fmt(self.as_str(), f)
1843 impl fmt::Display for Symbol {
1844 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1845 fmt::Display::fmt(self.as_str(), f)
1849 impl<S: Encoder> Encodable<S> for Symbol {
1850 fn encode(&self, s: &mut S) {
1851 s.emit_str(self.as_str());
1855 impl<D: Decoder> Decodable<D> for Symbol {
1857 fn decode(d: &mut D) -> Symbol {
1858 Symbol::intern(&d.read_str())
1862 impl<CTX> HashStable<CTX> for Symbol {
1864 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1865 self.as_str().hash_stable(hcx, hasher);
1869 impl<CTX> ToStableHashKey<CTX> for Symbol {
1870 type KeyType = String;
1872 fn to_stable_hash_key(&self, _: &CTX) -> String {
1873 self.as_str().to_string()
1878 pub(crate) struct Interner(Lock<InternerInner>);
1880 // The `&'static str`s in this type actually point into the arena.
1882 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1883 // found that to regress performance up to 2% in some cases. This might be
1884 // revisited after further improvements to `indexmap`.
1886 // This type is private to prevent accidentally constructing more than one
1887 // `Interner` on the same thread, which makes it easy to mix up `Symbol`s
1888 // between `Interner`s.
1890 struct InternerInner {
1891 arena: DroplessArena,
1892 names: FxHashMap<&'static str, Symbol>,
1893 strings: Vec<&'static str>,
1897 fn prefill(init: &[&'static str]) -> Self {
1898 Interner(Lock::new(InternerInner {
1899 strings: init.into(),
1900 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1901 ..Default::default()
1906 fn intern(&self, string: &str) -> Symbol {
1907 let mut inner = self.0.lock();
1908 if let Some(&name) = inner.names.get(string) {
1912 let name = Symbol::new(inner.strings.len() as u32);
1914 // SAFETY: we convert from `&str` to `&[u8]`, clone it into the arena,
1915 // and immediately convert the clone back to `&[u8], all because there
1916 // is no `inner.arena.alloc_str()` method. This is clearly safe.
1918 unsafe { str::from_utf8_unchecked(inner.arena.alloc_slice(string.as_bytes())) };
1920 // SAFETY: we can extend the arena allocation to `'static` because we
1921 // only access these while the arena is still alive.
1922 let string: &'static str = unsafe { &*(string as *const str) };
1923 inner.strings.push(string);
1925 // This second hash table lookup can be avoided by using `RawEntryMut`,
1926 // but this code path isn't hot enough for it to be worth it. See
1927 // #91445 for details.
1928 inner.names.insert(string, name);
1932 // Get the symbol as a string. `Symbol::as_str()` should be used in
1933 // preference to this function.
1934 fn get(&self, symbol: Symbol) -> &str {
1935 self.0.lock().strings[symbol.0.as_usize()]
1939 // This module has a very short name because it's used a lot.
1940 /// This module contains all the defined keyword `Symbol`s.
1942 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1943 /// For example `kw::Loop` or `kw::Break`.
1945 pub use super::kw_generated::*;
1948 // This module has a very short name because it's used a lot.
1949 /// This module contains all the defined non-keyword `Symbol`s.
1951 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1952 /// For example `sym::rustfmt` or `sym::u8`.
1955 use std::convert::TryInto;
1958 pub use super::sym_generated::*;
1960 // Used from a macro in `librustc_feature/accepted.rs`
1961 pub use super::kw::MacroRules as macro_rules;
1963 /// Get the symbol for an integer.
1965 /// The first few non-negative integers each have a static symbol and therefore
1967 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1968 if let Result::Ok(idx) = n.try_into() {
1970 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
1973 Symbol::intern(&n.to_string())
1978 fn is_special(self) -> bool {
1979 self <= kw::Underscore
1982 fn is_used_keyword_always(self) -> bool {
1983 self >= kw::As && self <= kw::While
1986 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1987 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
1990 fn is_unused_keyword_always(self) -> bool {
1991 self >= kw::Abstract && self <= kw::Yield
1994 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
1995 self == kw::Try && edition() >= Edition::Edition2018
1998 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
2000 || self.is_used_keyword_always()
2001 || self.is_unused_keyword_always()
2002 || self.is_used_keyword_conditional(edition)
2003 || self.is_unused_keyword_conditional(edition)
2006 /// A keyword or reserved identifier that can be used as a path segment.
2007 pub fn is_path_segment_keyword(self) -> bool {
2009 || self == kw::SelfLower
2010 || self == kw::SelfUpper
2011 || self == kw::Crate
2012 || self == kw::PathRoot
2013 || self == kw::DollarCrate
2016 /// Returns `true` if the symbol is `true` or `false`.
2017 pub fn is_bool_lit(self) -> bool {
2018 self == kw::True || self == kw::False
2021 /// Returns `true` if this symbol can be a raw identifier.
2022 pub fn can_be_raw(self) -> bool {
2023 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
2028 // Returns `true` for reserved identifiers used internally for elided lifetimes,
2029 // unnamed method parameters, crate root module, error recovery etc.
2030 pub fn is_special(self) -> bool {
2031 self.name.is_special()
2034 /// Returns `true` if the token is a keyword used in the language.
2035 pub fn is_used_keyword(self) -> bool {
2036 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2037 self.name.is_used_keyword_always()
2038 || self.name.is_used_keyword_conditional(|| self.span.edition())
2041 /// Returns `true` if the token is a keyword reserved for possible future use.
2042 pub fn is_unused_keyword(self) -> bool {
2043 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2044 self.name.is_unused_keyword_always()
2045 || self.name.is_unused_keyword_conditional(|| self.span.edition())
2048 /// Returns `true` if the token is either a special identifier or a keyword.
2049 pub fn is_reserved(self) -> bool {
2050 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2051 self.name.is_reserved(|| self.span.edition())
2054 /// A keyword or reserved identifier that can be used as a path segment.
2055 pub fn is_path_segment_keyword(self) -> bool {
2056 self.name.is_path_segment_keyword()
2059 /// We see this identifier in a normal identifier position, like variable name or a type.
2060 /// How was it written originally? Did it use the raw form? Let's try to guess.
2061 pub fn is_raw_guess(self) -> bool {
2062 self.name.can_be_raw() && self.is_reserved()