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};
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",
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
252 ProceduralMasqueradeDummyType,
282 SubdiagnosticMessage,
313 aarch64_target_feature,
314 aarch64_ver_target_feature,
318 abi_c_cmse_nonsecure_call,
320 abi_msp430_interrupt,
333 advanced_slice_patterns,
349 allow_internal_unsafe,
350 allow_internal_unstable,
356 anonymous_lifetime_in_impl_trait,
359 arbitrary_enum_discriminant,
360 arbitrary_self_types,
372 asm_experimental_arch,
379 assert_mem_uninitialized_valid,
381 assert_receiver_is_total_eq,
384 associated_const_equality,
386 associated_type_bounds,
387 associated_type_defaults,
401 augmented_assignments,
403 automatically_derived,
405 avx512_target_feature,
413 bind_by_move_pattern_guards,
425 borrowck_graphviz_format,
426 borrowck_graphviz_postflow,
431 braced_empty_structs,
443 capture_disjoint_fields,
460 cfg_target_has_atomic,
461 cfg_target_has_atomic_equal_alignment,
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,
487 compare_exchange_weak,
495 conservative_impl_trait,
499 const_compare_raw_pointers,
504 const_evaluatable_checked,
507 const_fn_floating_point_arithmetic,
508 const_fn_fn_ptr_basics,
509 const_fn_trait_bound,
516 const_generics_defaults,
519 const_in_array_repeat_expressions,
526 const_precise_live_drops,
528 const_raw_ptr_to_usize_cast,
531 const_trait_bound_opt_out,
544 core_panic_2015_macro,
545 core_panic_2021_macro,
556 crate_visibility_modifier,
557 crt_dash_static: "crt-static",
566 custom_inner_attributes,
568 custom_test_frameworks,
575 debug_assert_eq_macro,
577 debug_assert_ne_macro,
580 debug_struct_fields_finish,
582 debug_tuple_fields_finish,
587 default_alloc_error_handler,
588 default_lib_allocator,
589 default_method_body_is_const,
590 default_type_parameter_fallback,
592 delay_span_bug_from_inside_query,
596 deprecated_suggestion,
605 destructuring_assignment,
625 document_private_items,
627 dotdot_in_tuple_patterns,
628 dotdoteq_in_patterns,
636 dropck_parametricity,
647 emit_enum_variant_arg,
657 ermsb_target_feature,
661 exclusive_range_pattern,
662 exhaustive_integer_patterns,
671 explicit_generic_args_with_impl_trait,
674 extended_key_value_attributes,
675 extended_varargs_abi_support,
676 extern_absolute_paths,
677 extern_crate_item_prelude,
701 field_init_shorthand,
706 float_to_int_unchecked,
735 from_size_align_unchecked,
752 generic_associated_types,
753 generic_associated_types_extended,
761 half_open_range_patterns,
762 half_open_range_patterns_in_slices,
764 hexagon_target_feature,
766 homogeneous_aggregate,
784 if_while_or_patterns,
786 impl_header_lifetime_elision,
788 impl_trait_in_bindings,
789 impl_trait_in_fn_trait_return,
790 impl_trait_projections,
802 inclusive_range_syntax,
805 infer_outlives_requirements,
806 infer_static_outlives_requirements,
807 inherent_associated_types,
821 irrefutable_let_patterns,
825 issue_5723_bootstrap,
826 issue_tracker_base_url,
843 lazy_normalization_consts,
858 link_llvm_intrinsics,
879 macro_at_most_once_rep,
880 macro_attributes_in_derive_output,
883 macro_lifetime_matcher,
884 macro_literal_matcher,
897 match_beginning_vert,
898 match_default_bindings,
928 min_type_alias_impl_trait,
938 more_qualified_paths,
940 movbe_target_feature,
952 native_link_modifiers,
953 native_link_modifiers_as_needed,
954 native_link_modifiers_bundle,
955 native_link_modifiers_verbatim,
956 native_link_modifiers_whole_archive,
1005 non_exhaustive_omitted_patterns_lint,
1016 object_safe_for_dispatch,
1019 omit_gdb_pretty_printer_section,
1028 optin_builtin_traits,
1036 overlapping_marker_traits,
1048 panic_implementation,
1064 pattern_parentheses,
1067 platform_intrinsics,
1076 post_dash_lto: "post-lto",
1077 powerpc_target_feature,
1082 pre_dash_lto: "pre-lto",
1083 precise_pointer_size_matching,
1087 prefetch_read_instruction,
1088 prefetch_write_data,
1089 prefetch_write_instruction,
1097 proc_dash_macro: "proc-macro",
1099 proc_macro_attribute,
1104 proc_macro_internals,
1106 proc_macro_non_items,
1107 proc_macro_path_invoc,
1116 ptr_offset_from_unsigned,
1125 quad_precision_float,
1128 range_inclusive_new,
1133 re_rebalance_coherence,
1136 read_enum_variant_arg,
1144 reexport_test_harness_main,
1145 ref_unwind_safe_trait,
1162 relaxed_struct_unsize,
1175 return_position_impl_trait_in_trait,
1179 riscv_target_feature,
1198 rust_eh_catch_typeinfo,
1199 rust_eh_personality,
1202 rustc_allocator_zeroed,
1203 rustc_allow_const_fn_unstable,
1204 rustc_allow_incoherent_impl,
1205 rustc_allowed_through_unstable_modules,
1208 rustc_builtin_macro,
1209 rustc_capture_analysis,
1211 rustc_coherence_is_core,
1213 rustc_const_unstable,
1214 rustc_conversion_suggestion,
1217 rustc_default_body_unstable,
1218 rustc_deny_explicit_impl,
1219 rustc_diagnostic_item,
1220 rustc_diagnostic_macros,
1222 rustc_do_not_const_check,
1224 rustc_dump_env_program_clauses,
1225 rustc_dump_program_clauses,
1226 rustc_dump_user_substs,
1228 rustc_effective_visibility,
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_opt_deny_field_access,
1243 rustc_lint_query_instability,
1244 rustc_macro_transparency,
1247 rustc_must_implement_one_of,
1248 rustc_nonnull_optimization_guaranteed,
1250 rustc_object_lifetime_default,
1251 rustc_on_unimplemented,
1254 rustc_partition_codegened,
1255 rustc_partition_reused,
1256 rustc_pass_by_value,
1258 rustc_peek_definite_init,
1259 rustc_peek_liveness,
1260 rustc_peek_maybe_init,
1261 rustc_peek_maybe_uninit,
1262 rustc_polymorphize_error,
1264 rustc_proc_macro_decls,
1268 rustc_reservation_impl,
1269 rustc_safe_intrinsic,
1271 rustc_skip_array_during_method_dispatch,
1272 rustc_specialization_trait,
1273 rustc_std_internal_symbol,
1274 rustc_strict_coherence,
1277 rustc_then_this_would_need,
1278 rustc_trivial_field_reads,
1279 rustc_unsafe_specialization_marker,
1283 rustdoc_missing_doc_code_examples,
1285 rvalue_static_promotion,
1330 simd_from_exposed_addr,
1343 simd_reduce_add_ordered,
1344 simd_reduce_add_unordered,
1349 simd_reduce_max_nanless,
1351 simd_reduce_min_nanless,
1352 simd_reduce_mul_ordered,
1353 simd_reduce_mul_unordered,
1358 simd_saturating_add,
1359 simd_saturating_sub,
1362 simd_select_bitmask,
1390 sse4a_target_feature,
1401 std_panic_2015_macro,
1404 stmt_expr_attributes,
1405 stop_after_dataflow,
1408 str_split_whitespace,
1413 string_deref_patterns,
1415 struct_field_attributes,
1438 target_has_atomic_equal_alignment,
1439 target_has_atomic_load_store,
1441 target_pointer_width,
1442 target_thread_local,
1447 termination_trait_test,
1450 test_accepted_feature,
1452 test_removed_feature,
1459 thumb_mode: "thumb-mode",
1490 type_alias_enum_variants,
1491 type_alias_impl_trait,
1494 type_changing_struct_update,
1504 unaligned_volatile_load,
1505 unaligned_volatile_store,
1514 underscore_const_names,
1516 underscore_lifetimes,
1518 unimplemented_macro,
1520 universal_impl_trait,
1528 unreachable_2015_macro,
1531 unreachable_display,
1533 unrestricted_attribute_tokens,
1534 unsafe_block_in_unsafe_fn,
1536 unsafe_no_drop_flag,
1537 unsafe_pin_internals,
1541 unsized_tuple_coercion,
1543 unstable_location_reason_default: "this crate is being loaded from the sysroot, an \
1544 unstable location; did you mean to load this crate \
1545 from crates.io via `Cargo.toml` instead?",
1575 visible_private_types,
1577 volatile_copy_memory,
1578 volatile_copy_nonoverlapping_memory,
1580 volatile_set_memory,
1589 wasm_target_feature,
1594 with_negative_coherence,
1606 yeet_desugar_details,
1613 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1621 /// Constructs a new identifier from a symbol and a span.
1622 pub const fn new(name: Symbol, span: Span) -> Ident {
1623 Ident { name, span }
1626 /// Constructs a new identifier with a dummy span.
1628 pub const fn with_dummy_span(name: Symbol) -> Ident {
1629 Ident::new(name, DUMMY_SP)
1633 pub fn empty() -> Ident {
1634 Ident::with_dummy_span(kw::Empty)
1637 /// Maps a string to an identifier with a dummy span.
1638 pub fn from_str(string: &str) -> Ident {
1639 Ident::with_dummy_span(Symbol::intern(string))
1642 /// Maps a string and a span to an identifier.
1643 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1644 Ident::new(Symbol::intern(string), span)
1647 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1648 pub fn with_span_pos(self, span: Span) -> Ident {
1649 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1652 pub fn without_first_quote(self) -> Ident {
1653 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1656 /// "Normalize" ident for use in comparisons using "item hygiene".
1657 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1658 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1659 /// different macro 2.0 macros.
1660 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1661 pub fn normalize_to_macros_2_0(self) -> Ident {
1662 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1665 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1666 /// Identifiers with same string value become same if they came from the same non-transparent
1667 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1668 /// non-transparent macros.
1669 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1671 pub fn normalize_to_macro_rules(self) -> Ident {
1672 Ident::new(self.name, self.span.normalize_to_macro_rules())
1675 /// Access the underlying string. This is a slowish operation because it
1676 /// requires locking the symbol interner.
1678 /// Note that the lifetime of the return value is a lie. See
1679 /// `Symbol::as_str()` for details.
1680 pub fn as_str(&self) -> &str {
1685 impl PartialEq for Ident {
1687 fn eq(&self, rhs: &Self) -> bool {
1688 self.name == rhs.name && self.span.eq_ctxt(rhs.span)
1692 impl Hash for Ident {
1693 fn hash<H: Hasher>(&self, state: &mut H) {
1694 self.name.hash(state);
1695 self.span.ctxt().hash(state);
1699 impl fmt::Debug for Ident {
1700 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1701 fmt::Display::fmt(self, f)?;
1702 fmt::Debug::fmt(&self.span.ctxt(), f)
1706 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1707 /// to printing the original identifier token written in source code (`token_to_string`),
1708 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1709 impl fmt::Display for Ident {
1710 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1711 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1715 /// The most general type to print identifiers.
1717 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1718 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1719 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1720 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1721 /// hygiene data, most importantly name of the crate it refers to.
1722 /// As a result we print `$crate` as `crate` if it refers to the local crate
1723 /// and as `::other_crate_name` if it refers to some other crate.
1724 /// Note, that this is only done if the ident token is printed from inside of AST pretty-printing,
1725 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1726 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1727 /// done for a token stream or a single token.
1728 pub struct IdentPrinter {
1731 /// Span used for retrieving the crate name to which `$crate` refers to,
1732 /// if this field is `None` then the `$crate` conversion doesn't happen.
1733 convert_dollar_crate: Option<Span>,
1737 /// The most general `IdentPrinter` constructor. Do not use this.
1738 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1739 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1742 /// This implementation is supposed to be used when printing identifiers
1743 /// as a part of pretty-printing for larger AST pieces.
1744 /// Do not use this either.
1745 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1746 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1750 impl fmt::Display for IdentPrinter {
1751 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1754 } else if self.symbol == kw::DollarCrate {
1755 if let Some(span) = self.convert_dollar_crate {
1756 let converted = span.ctxt().dollar_crate_name();
1757 if !converted.is_path_segment_keyword() {
1760 return fmt::Display::fmt(&converted, f);
1763 fmt::Display::fmt(&self.symbol, f)
1767 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1769 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1770 // `ModernIdent` struct and use that as well.
1771 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1772 pub struct MacroRulesNormalizedIdent(Ident);
1774 impl MacroRulesNormalizedIdent {
1775 pub fn new(ident: Ident) -> Self {
1776 Self(ident.normalize_to_macro_rules())
1780 impl fmt::Debug for MacroRulesNormalizedIdent {
1781 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1782 fmt::Debug::fmt(&self.0, f)
1786 impl fmt::Display for MacroRulesNormalizedIdent {
1787 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1788 fmt::Display::fmt(&self.0, f)
1792 /// An interned string.
1794 /// Internally, a `Symbol` is implemented as an index, and all operations
1795 /// (including hashing, equality, and ordering) operate on that index. The use
1796 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1797 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1799 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1800 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1801 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1802 pub struct Symbol(SymbolIndex);
1804 rustc_index::newtype_index! {
1805 struct SymbolIndex {}
1809 const fn new(n: u32) -> Self {
1810 Symbol(SymbolIndex::from_u32(n))
1813 /// for use in Decoder only
1814 pub fn new_from_decoded(n: u32) -> Self {
1818 /// Maps a string to its interned representation.
1819 pub fn intern(string: &str) -> Self {
1820 with_session_globals(|session_globals| session_globals.symbol_interner.intern(string))
1823 /// Access the underlying string. This is a slowish operation because it
1824 /// requires locking the symbol interner.
1826 /// Note that the lifetime of the return value is a lie. It's not the same
1827 /// as `&self`, but actually tied to the lifetime of the underlying
1828 /// interner. Interners are long-lived, and there are very few of them, and
1829 /// this function is typically used for short-lived things, so in practice
1830 /// it works out ok.
1831 pub fn as_str(&self) -> &str {
1832 with_session_globals(|session_globals| unsafe {
1833 std::mem::transmute::<&str, &str>(session_globals.symbol_interner.get(*self))
1837 pub fn as_u32(self) -> u32 {
1841 pub fn is_empty(self) -> bool {
1845 /// This method is supposed to be used in error messages, so it's expected to be
1846 /// identical to printing the original identifier token written in source code
1847 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1848 /// or edition, so we have to guess the rawness using the global edition.
1849 pub fn to_ident_string(self) -> String {
1850 Ident::with_dummy_span(self).to_string()
1854 impl fmt::Debug for Symbol {
1855 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1856 fmt::Debug::fmt(self.as_str(), f)
1860 impl fmt::Display for Symbol {
1861 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1862 fmt::Display::fmt(self.as_str(), f)
1866 // takes advantage of `str::to_string` specialization
1867 impl ToString for Symbol {
1868 fn to_string(&self) -> String {
1869 self.as_str().to_string()
1873 impl<S: Encoder> Encodable<S> for Symbol {
1874 default fn encode(&self, s: &mut S) {
1875 s.emit_str(self.as_str());
1879 impl<D: Decoder> Decodable<D> for Symbol {
1881 default fn decode(d: &mut D) -> Symbol {
1882 Symbol::intern(d.read_str())
1886 impl<CTX> HashStable<CTX> for Symbol {
1888 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1889 self.as_str().hash_stable(hcx, hasher);
1893 impl<CTX> ToStableHashKey<CTX> for Symbol {
1894 type KeyType = String;
1896 fn to_stable_hash_key(&self, _: &CTX) -> String {
1897 self.as_str().to_string()
1902 pub(crate) struct Interner(Lock<InternerInner>);
1904 // The `&'static str`s in this type actually point into the arena.
1906 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1907 // found that to regress performance up to 2% in some cases. This might be
1908 // revisited after further improvements to `indexmap`.
1910 // This type is private to prevent accidentally constructing more than one
1911 // `Interner` on the same thread, which makes it easy to mix up `Symbol`s
1912 // between `Interner`s.
1914 struct InternerInner {
1915 arena: DroplessArena,
1916 names: FxHashMap<&'static str, Symbol>,
1917 strings: Vec<&'static str>,
1921 fn prefill(init: &[&'static str]) -> Self {
1922 Interner(Lock::new(InternerInner {
1923 strings: init.into(),
1924 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1925 ..Default::default()
1930 fn intern(&self, string: &str) -> Symbol {
1931 let mut inner = self.0.lock();
1932 if let Some(&name) = inner.names.get(string) {
1936 let name = Symbol::new(inner.strings.len() as u32);
1938 // SAFETY: we convert from `&str` to `&[u8]`, clone it into the arena,
1939 // and immediately convert the clone back to `&[u8], all because there
1940 // is no `inner.arena.alloc_str()` method. This is clearly safe.
1942 unsafe { str::from_utf8_unchecked(inner.arena.alloc_slice(string.as_bytes())) };
1944 // SAFETY: we can extend the arena allocation to `'static` because we
1945 // only access these while the arena is still alive.
1946 let string: &'static str = unsafe { &*(string as *const str) };
1947 inner.strings.push(string);
1949 // This second hash table lookup can be avoided by using `RawEntryMut`,
1950 // but this code path isn't hot enough for it to be worth it. See
1951 // #91445 for details.
1952 inner.names.insert(string, name);
1956 // Get the symbol as a string. `Symbol::as_str()` should be used in
1957 // preference to this function.
1958 fn get(&self, symbol: Symbol) -> &str {
1959 self.0.lock().strings[symbol.0.as_usize()]
1963 // This module has a very short name because it's used a lot.
1964 /// This module contains all the defined keyword `Symbol`s.
1966 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1967 /// For example `kw::Loop` or `kw::Break`.
1969 pub use super::kw_generated::*;
1972 // This module has a very short name because it's used a lot.
1973 /// This module contains all the defined non-keyword `Symbol`s.
1975 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1976 /// For example `sym::rustfmt` or `sym::u8`.
1981 pub use super::sym_generated::*;
1983 // Used from a macro in `librustc_feature/accepted.rs`
1984 pub use super::kw::MacroRules as macro_rules;
1986 /// Get the symbol for an integer.
1988 /// The first few non-negative integers each have a static symbol and therefore
1990 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1991 if let Result::Ok(idx) = n.try_into() {
1993 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
1996 Symbol::intern(&n.to_string())
2001 fn is_special(self) -> bool {
2002 self <= kw::Underscore
2005 fn is_used_keyword_always(self) -> bool {
2006 self >= kw::As && self <= kw::While
2009 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
2010 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
2013 fn is_unused_keyword_always(self) -> bool {
2014 self >= kw::Abstract && self <= kw::Yield
2017 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
2018 self == kw::Try && edition() >= Edition::Edition2018
2021 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
2023 || self.is_used_keyword_always()
2024 || self.is_unused_keyword_always()
2025 || self.is_used_keyword_conditional(edition)
2026 || self.is_unused_keyword_conditional(edition)
2029 /// A keyword or reserved identifier that can be used as a path segment.
2030 pub fn is_path_segment_keyword(self) -> bool {
2032 || self == kw::SelfLower
2033 || self == kw::SelfUpper
2034 || self == kw::Crate
2035 || self == kw::PathRoot
2036 || self == kw::DollarCrate
2039 /// Returns `true` if the symbol is `true` or `false`.
2040 pub fn is_bool_lit(self) -> bool {
2041 self == kw::True || self == kw::False
2044 /// Returns `true` if this symbol can be a raw identifier.
2045 pub fn can_be_raw(self) -> bool {
2046 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
2049 /// Is this symbol was interned in compiler's `symbols!` macro
2050 pub fn is_preinterned(self) -> bool {
2051 self.as_u32() < PREINTERNED_SYMBOLS_COUNT
2056 /// Returns `true` for reserved identifiers used internally for elided lifetimes,
2057 /// unnamed method parameters, crate root module, error recovery etc.
2058 pub fn is_special(self) -> bool {
2059 self.name.is_special()
2062 /// Returns `true` if the token is a keyword used in the language.
2063 pub fn is_used_keyword(self) -> bool {
2064 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2065 self.name.is_used_keyword_always()
2066 || self.name.is_used_keyword_conditional(|| self.span.edition())
2069 /// Returns `true` if the token is a keyword reserved for possible future use.
2070 pub fn is_unused_keyword(self) -> bool {
2071 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2072 self.name.is_unused_keyword_always()
2073 || self.name.is_unused_keyword_conditional(|| self.span.edition())
2076 /// Returns `true` if the token is either a special identifier or a keyword.
2077 pub fn is_reserved(self) -> bool {
2078 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2079 self.name.is_reserved(|| self.span.edition())
2082 /// A keyword or reserved identifier that can be used as a path segment.
2083 pub fn is_path_segment_keyword(self) -> bool {
2084 self.name.is_path_segment_keyword()
2087 /// We see this identifier in a normal identifier position, like variable name or a type.
2088 /// How was it written originally? Did it use the raw form? Let's try to guess.
2089 pub fn is_raw_guess(self) -> bool {
2090 self.name.can_be_raw() && self.is_reserved()