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
255 ProceduralMasqueradeDummyType,
285 SubdiagnosticMessage,
317 aarch64_target_feature,
318 aarch64_ver_target_feature,
322 abi_c_cmse_nonsecure_call,
324 abi_msp430_interrupt,
337 advanced_slice_patterns,
353 allow_internal_unsafe,
354 allow_internal_unstable,
360 anonymous_lifetime_in_impl_trait,
363 arbitrary_enum_discriminant,
364 arbitrary_self_types,
376 asm_experimental_arch,
383 assert_mem_uninitialized_valid,
385 assert_receiver_is_total_eq,
388 associated_const_equality,
390 associated_type_bounds,
391 associated_type_defaults,
405 augmented_assignments,
407 automatically_derived,
409 avx512_target_feature,
417 bind_by_move_pattern_guards,
429 borrowck_graphviz_format,
430 borrowck_graphviz_postflow,
435 braced_empty_structs,
447 capture_disjoint_fields,
464 cfg_target_has_atomic,
465 cfg_target_has_atomic_equal_alignment,
466 cfg_target_thread_local,
478 closure_lifetime_binder,
479 closure_to_fn_coercion,
480 closure_track_caller,
484 cmpxchg16b_target_feature,
485 cmse_nonsecure_entry,
491 compare_exchange_weak,
499 conservative_impl_trait,
504 const_compare_raw_pointers,
509 const_evaluatable_checked,
512 const_fn_floating_point_arithmetic,
513 const_fn_fn_ptr_basics,
514 const_fn_trait_bound,
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,
549 core_panic_2015_macro,
550 core_panic_2021_macro,
561 crate_visibility_modifier,
562 crt_dash_static: "crt-static",
571 custom_inner_attributes,
573 custom_test_frameworks,
580 debug_assert_eq_macro,
582 debug_assert_ne_macro,
585 debug_struct_fields_finish,
587 debug_tuple_fields_finish,
592 default_alloc_error_handler,
593 default_lib_allocator,
594 default_method_body_is_const,
595 default_type_parameter_fallback,
597 delay_span_bug_from_inside_query,
601 deprecated_suggestion,
610 destructuring_assignment,
631 document_private_items,
633 dotdot_in_tuple_patterns,
634 dotdoteq_in_patterns,
642 dropck_parametricity,
653 emit_enum_variant_arg,
663 ermsb_target_feature,
667 exclusive_range_pattern,
668 exhaustive_integer_patterns,
677 explicit_generic_args_with_impl_trait,
680 extended_key_value_attributes,
681 extended_varargs_abi_support,
682 extern_absolute_paths,
683 extern_crate_item_prelude,
707 field_init_shorthand,
712 float_to_int_unchecked,
747 from_size_align_unchecked,
764 generic_associated_types,
765 generic_associated_types_extended,
773 half_open_range_patterns,
774 half_open_range_patterns_in_slices,
776 hexagon_target_feature,
778 homogeneous_aggregate,
796 if_while_or_patterns,
798 impl_header_lifetime_elision,
800 impl_trait_in_bindings,
801 impl_trait_in_fn_trait_return,
802 impl_trait_projections,
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,
855 lazy_normalization_consts,
870 link_llvm_intrinsics,
891 macro_at_most_once_rep,
892 macro_attributes_in_derive_output,
895 macro_lifetime_matcher,
896 macro_literal_matcher,
909 match_beginning_vert,
910 match_default_bindings,
940 min_type_alias_impl_trait,
950 more_qualified_paths,
952 movbe_target_feature,
958 multiple_supertrait_upcastable,
965 native_link_modifiers,
966 native_link_modifiers_as_needed,
967 native_link_modifiers_bundle,
968 native_link_modifiers_verbatim,
969 native_link_modifiers_whole_archive,
1006 no_implicit_prelude,
1018 non_exhaustive_omitted_patterns_lint,
1029 object_safe_for_dispatch,
1032 omit_gdb_pretty_printer_section,
1041 optin_builtin_traits,
1049 overlapping_marker_traits,
1057 panic_cannot_unwind,
1062 panic_implementation,
1078 pattern_parentheses,
1081 platform_intrinsics,
1090 post_dash_lto: "post-lto",
1091 powerpc_target_feature,
1096 pre_dash_lto: "pre-lto",
1097 precise_pointer_size_matching,
1101 prefetch_read_instruction,
1102 prefetch_write_data,
1103 prefetch_write_instruction,
1111 proc_dash_macro: "proc-macro",
1113 proc_macro_attribute,
1118 proc_macro_internals,
1120 proc_macro_non_items,
1121 proc_macro_path_invoc,
1130 ptr_offset_from_unsigned,
1139 quad_precision_float,
1142 range_inclusive_new,
1147 re_rebalance_coherence,
1150 read_enum_variant_arg,
1158 reexport_test_harness_main,
1159 ref_unwind_safe_trait,
1176 relaxed_struct_unsize,
1189 return_position_impl_trait_in_trait,
1193 riscv_target_feature,
1212 rust_eh_catch_typeinfo,
1213 rust_eh_personality,
1216 rustc_allocator_zeroed,
1217 rustc_allow_const_fn_unstable,
1218 rustc_allow_incoherent_impl,
1219 rustc_allowed_through_unstable_modules,
1222 rustc_builtin_macro,
1223 rustc_capture_analysis,
1225 rustc_coherence_is_core,
1227 rustc_const_unstable,
1228 rustc_conversion_suggestion,
1231 rustc_default_body_unstable,
1232 rustc_deny_explicit_impl,
1233 rustc_diagnostic_item,
1234 rustc_diagnostic_macros,
1236 rustc_do_not_const_check,
1238 rustc_dump_env_program_clauses,
1239 rustc_dump_program_clauses,
1240 rustc_dump_user_substs,
1242 rustc_effective_visibility,
1244 rustc_evaluate_where_clauses,
1245 rustc_expected_cgu_reuse,
1246 rustc_has_incoherent_inherent_impls,
1247 rustc_if_this_changed,
1248 rustc_inherit_overflow_checks,
1249 rustc_insignificant_dtor,
1251 rustc_layout_scalar_valid_range_end,
1252 rustc_layout_scalar_valid_range_start,
1253 rustc_legacy_const_generics,
1254 rustc_lint_diagnostics,
1255 rustc_lint_opt_deny_field_access,
1257 rustc_lint_query_instability,
1258 rustc_macro_transparency,
1261 rustc_must_implement_one_of,
1262 rustc_nonnull_optimization_guaranteed,
1264 rustc_object_lifetime_default,
1265 rustc_on_unimplemented,
1268 rustc_partition_codegened,
1269 rustc_partition_reused,
1270 rustc_pass_by_value,
1272 rustc_peek_definite_init,
1273 rustc_peek_liveness,
1274 rustc_peek_maybe_init,
1275 rustc_peek_maybe_uninit,
1276 rustc_polymorphize_error,
1278 rustc_proc_macro_decls,
1282 rustc_reservation_impl,
1283 rustc_safe_intrinsic,
1285 rustc_skip_array_during_method_dispatch,
1286 rustc_specialization_trait,
1287 rustc_std_internal_symbol,
1288 rustc_strict_coherence,
1291 rustc_then_this_would_need,
1292 rustc_trivial_field_reads,
1293 rustc_unsafe_specialization_marker,
1297 rustdoc_missing_doc_code_examples,
1299 rvalue_static_promotion,
1344 simd_from_exposed_addr,
1357 simd_reduce_add_ordered,
1358 simd_reduce_add_unordered,
1363 simd_reduce_max_nanless,
1365 simd_reduce_min_nanless,
1366 simd_reduce_mul_ordered,
1367 simd_reduce_mul_unordered,
1372 simd_saturating_add,
1373 simd_saturating_sub,
1376 simd_select_bitmask,
1404 sse4a_target_feature,
1415 std_panic_2015_macro,
1418 stmt_expr_attributes,
1419 stop_after_dataflow,
1422 str_split_whitespace,
1427 string_deref_patterns,
1429 struct_field_attributes,
1452 target_has_atomic_equal_alignment,
1453 target_has_atomic_load_store,
1455 target_pointer_width,
1456 target_thread_local,
1461 termination_trait_test,
1464 test_accepted_feature,
1466 test_removed_feature,
1473 thumb_mode: "thumb-mode",
1504 type_alias_enum_variants,
1505 type_alias_impl_trait,
1508 type_changing_struct_update,
1518 unaligned_volatile_load,
1519 unaligned_volatile_store,
1528 underscore_const_names,
1530 underscore_lifetimes,
1532 unimplemented_macro,
1534 universal_impl_trait,
1542 unreachable_2015_macro,
1545 unreachable_display,
1547 unrestricted_attribute_tokens,
1548 unsafe_block_in_unsafe_fn,
1550 unsafe_no_drop_flag,
1551 unsafe_pin_internals,
1555 unsized_tuple_coercion,
1557 unstable_location_reason_default: "this crate is being loaded from the sysroot, an \
1558 unstable location; did you mean to load this crate \
1559 from crates.io via `Cargo.toml` instead?",
1589 visible_private_types,
1591 volatile_copy_memory,
1592 volatile_copy_nonoverlapping_memory,
1594 volatile_set_memory,
1603 wasm_target_feature,
1608 with_negative_coherence,
1620 yeet_desugar_details,
1627 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1635 /// Constructs a new identifier from a symbol and a span.
1636 pub const fn new(name: Symbol, span: Span) -> Ident {
1637 Ident { name, span }
1640 /// Constructs a new identifier with a dummy span.
1642 pub const fn with_dummy_span(name: Symbol) -> Ident {
1643 Ident::new(name, DUMMY_SP)
1647 pub fn empty() -> Ident {
1648 Ident::with_dummy_span(kw::Empty)
1651 /// Maps a string to an identifier with a dummy span.
1652 pub fn from_str(string: &str) -> Ident {
1653 Ident::with_dummy_span(Symbol::intern(string))
1656 /// Maps a string and a span to an identifier.
1657 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1658 Ident::new(Symbol::intern(string), span)
1661 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1662 pub fn with_span_pos(self, span: Span) -> Ident {
1663 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1666 pub fn without_first_quote(self) -> Ident {
1667 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1670 /// "Normalize" ident for use in comparisons using "item hygiene".
1671 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1672 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1673 /// different macro 2.0 macros.
1674 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1675 pub fn normalize_to_macros_2_0(self) -> Ident {
1676 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1679 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1680 /// Identifiers with same string value become same if they came from the same non-transparent
1681 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1682 /// non-transparent macros.
1683 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1685 pub fn normalize_to_macro_rules(self) -> Ident {
1686 Ident::new(self.name, self.span.normalize_to_macro_rules())
1689 /// Access the underlying string. This is a slowish operation because it
1690 /// requires locking the symbol interner.
1692 /// Note that the lifetime of the return value is a lie. See
1693 /// `Symbol::as_str()` for details.
1694 pub fn as_str(&self) -> &str {
1699 impl PartialEq for Ident {
1701 fn eq(&self, rhs: &Self) -> bool {
1702 self.name == rhs.name && self.span.eq_ctxt(rhs.span)
1706 impl Hash for Ident {
1707 fn hash<H: Hasher>(&self, state: &mut H) {
1708 self.name.hash(state);
1709 self.span.ctxt().hash(state);
1713 impl fmt::Debug for Ident {
1714 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1715 fmt::Display::fmt(self, f)?;
1716 fmt::Debug::fmt(&self.span.ctxt(), f)
1720 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1721 /// to printing the original identifier token written in source code (`token_to_string`),
1722 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1723 impl fmt::Display for Ident {
1724 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1725 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1729 /// The most general type to print identifiers.
1731 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1732 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1733 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1734 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1735 /// hygiene data, most importantly name of the crate it refers to.
1736 /// As a result we print `$crate` as `crate` if it refers to the local crate
1737 /// and as `::other_crate_name` if it refers to some other crate.
1738 /// Note, that this is only done if the ident token is printed from inside of AST pretty-printing,
1739 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1740 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1741 /// done for a token stream or a single token.
1742 pub struct IdentPrinter {
1745 /// Span used for retrieving the crate name to which `$crate` refers to,
1746 /// if this field is `None` then the `$crate` conversion doesn't happen.
1747 convert_dollar_crate: Option<Span>,
1751 /// The most general `IdentPrinter` constructor. Do not use this.
1752 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1753 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1756 /// This implementation is supposed to be used when printing identifiers
1757 /// as a part of pretty-printing for larger AST pieces.
1758 /// Do not use this either.
1759 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1760 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1764 impl fmt::Display for IdentPrinter {
1765 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1768 } else if self.symbol == kw::DollarCrate {
1769 if let Some(span) = self.convert_dollar_crate {
1770 let converted = span.ctxt().dollar_crate_name();
1771 if !converted.is_path_segment_keyword() {
1774 return fmt::Display::fmt(&converted, f);
1777 fmt::Display::fmt(&self.symbol, f)
1781 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1783 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1784 // `ModernIdent` struct and use that as well.
1785 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1786 pub struct MacroRulesNormalizedIdent(Ident);
1788 impl MacroRulesNormalizedIdent {
1789 pub fn new(ident: Ident) -> Self {
1790 Self(ident.normalize_to_macro_rules())
1794 impl fmt::Debug for MacroRulesNormalizedIdent {
1795 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1796 fmt::Debug::fmt(&self.0, f)
1800 impl fmt::Display for MacroRulesNormalizedIdent {
1801 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1802 fmt::Display::fmt(&self.0, f)
1806 /// An interned string.
1808 /// Internally, a `Symbol` is implemented as an index, and all operations
1809 /// (including hashing, equality, and ordering) operate on that index. The use
1810 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1811 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1813 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1814 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1815 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1816 pub struct Symbol(SymbolIndex);
1818 rustc_index::newtype_index! {
1819 struct SymbolIndex {}
1823 const fn new(n: u32) -> Self {
1824 Symbol(SymbolIndex::from_u32(n))
1827 /// for use in Decoder only
1828 pub fn new_from_decoded(n: u32) -> Self {
1832 /// Maps a string to its interned representation.
1833 pub fn intern(string: &str) -> Self {
1834 with_session_globals(|session_globals| session_globals.symbol_interner.intern(string))
1837 /// Access the underlying string. This is a slowish operation because it
1838 /// requires locking the symbol interner.
1840 /// Note that the lifetime of the return value is a lie. It's not the same
1841 /// as `&self`, but actually tied to the lifetime of the underlying
1842 /// interner. Interners are long-lived, and there are very few of them, and
1843 /// this function is typically used for short-lived things, so in practice
1844 /// it works out ok.
1845 pub fn as_str(&self) -> &str {
1846 with_session_globals(|session_globals| unsafe {
1847 std::mem::transmute::<&str, &str>(session_globals.symbol_interner.get(*self))
1851 pub fn as_u32(self) -> u32 {
1855 pub fn is_empty(self) -> bool {
1859 /// This method is supposed to be used in error messages, so it's expected to be
1860 /// identical to printing the original identifier token written in source code
1861 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1862 /// or edition, so we have to guess the rawness using the global edition.
1863 pub fn to_ident_string(self) -> String {
1864 Ident::with_dummy_span(self).to_string()
1868 impl fmt::Debug for Symbol {
1869 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1870 fmt::Debug::fmt(self.as_str(), f)
1874 impl fmt::Display for Symbol {
1875 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1876 fmt::Display::fmt(self.as_str(), f)
1880 // takes advantage of `str::to_string` specialization
1881 impl ToString for Symbol {
1882 fn to_string(&self) -> String {
1883 self.as_str().to_string()
1887 impl<S: Encoder> Encodable<S> for Symbol {
1888 default fn encode(&self, s: &mut S) {
1889 s.emit_str(self.as_str());
1893 impl<D: Decoder> Decodable<D> for Symbol {
1895 default fn decode(d: &mut D) -> Symbol {
1896 Symbol::intern(d.read_str())
1900 impl<CTX> HashStable<CTX> for Symbol {
1902 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1903 self.as_str().hash_stable(hcx, hasher);
1907 impl<CTX> ToStableHashKey<CTX> for Symbol {
1908 type KeyType = String;
1910 fn to_stable_hash_key(&self, _: &CTX) -> String {
1911 self.as_str().to_string()
1916 pub(crate) struct Interner(Lock<InternerInner>);
1918 // The `&'static str`s in this type actually point into the arena.
1920 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1921 // found that to regress performance up to 2% in some cases. This might be
1922 // revisited after further improvements to `indexmap`.
1924 // This type is private to prevent accidentally constructing more than one
1925 // `Interner` on the same thread, which makes it easy to mix up `Symbol`s
1926 // between `Interner`s.
1928 struct InternerInner {
1929 arena: DroplessArena,
1930 names: FxHashMap<&'static str, Symbol>,
1931 strings: Vec<&'static str>,
1935 fn prefill(init: &[&'static str]) -> Self {
1936 Interner(Lock::new(InternerInner {
1937 strings: init.into(),
1938 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1939 ..Default::default()
1944 fn intern(&self, string: &str) -> Symbol {
1945 let mut inner = self.0.lock();
1946 if let Some(&name) = inner.names.get(string) {
1950 let name = Symbol::new(inner.strings.len() as u32);
1952 // SAFETY: we convert from `&str` to `&[u8]`, clone it into the arena,
1953 // and immediately convert the clone back to `&[u8], all because there
1954 // is no `inner.arena.alloc_str()` method. This is clearly safe.
1956 unsafe { str::from_utf8_unchecked(inner.arena.alloc_slice(string.as_bytes())) };
1958 // SAFETY: we can extend the arena allocation to `'static` because we
1959 // only access these while the arena is still alive.
1960 let string: &'static str = unsafe { &*(string as *const str) };
1961 inner.strings.push(string);
1963 // This second hash table lookup can be avoided by using `RawEntryMut`,
1964 // but this code path isn't hot enough for it to be worth it. See
1965 // #91445 for details.
1966 inner.names.insert(string, name);
1970 // Get the symbol as a string. `Symbol::as_str()` should be used in
1971 // preference to this function.
1972 fn get(&self, symbol: Symbol) -> &str {
1973 self.0.lock().strings[symbol.0.as_usize()]
1977 // This module has a very short name because it's used a lot.
1978 /// This module contains all the defined keyword `Symbol`s.
1980 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1981 /// For example `kw::Loop` or `kw::Break`.
1983 pub use super::kw_generated::*;
1986 // This module has a very short name because it's used a lot.
1987 /// This module contains all the defined non-keyword `Symbol`s.
1989 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1990 /// For example `sym::rustfmt` or `sym::u8`.
1995 pub use super::sym_generated::*;
1997 // Used from a macro in `librustc_feature/accepted.rs`
1998 pub use super::kw::MacroRules as macro_rules;
2000 /// Get the symbol for an integer.
2002 /// The first few non-negative integers each have a static symbol and therefore
2004 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
2005 if let Result::Ok(idx) = n.try_into() {
2007 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
2010 Symbol::intern(&n.to_string())
2015 fn is_special(self) -> bool {
2016 self <= kw::Underscore
2019 fn is_used_keyword_always(self) -> bool {
2020 self >= kw::As && self <= kw::While
2023 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
2024 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
2027 fn is_unused_keyword_always(self) -> bool {
2028 self >= kw::Abstract && self <= kw::Yield
2031 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
2032 self == kw::Try && edition() >= Edition::Edition2018
2035 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
2037 || self.is_used_keyword_always()
2038 || self.is_unused_keyword_always()
2039 || self.is_used_keyword_conditional(edition)
2040 || self.is_unused_keyword_conditional(edition)
2043 /// A keyword or reserved identifier that can be used as a path segment.
2044 pub fn is_path_segment_keyword(self) -> bool {
2046 || self == kw::SelfLower
2047 || self == kw::SelfUpper
2048 || self == kw::Crate
2049 || self == kw::PathRoot
2050 || self == kw::DollarCrate
2053 /// Returns `true` if the symbol is `true` or `false`.
2054 pub fn is_bool_lit(self) -> bool {
2055 self == kw::True || self == kw::False
2058 /// Returns `true` if this symbol can be a raw identifier.
2059 pub fn can_be_raw(self) -> bool {
2060 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
2063 /// Is this symbol was interned in compiler's `symbols!` macro
2064 pub fn is_preinterned(self) -> bool {
2065 self.as_u32() < PREINTERNED_SYMBOLS_COUNT
2070 /// Returns `true` for reserved identifiers used internally for elided lifetimes,
2071 /// unnamed method parameters, crate root module, error recovery etc.
2072 pub fn is_special(self) -> bool {
2073 self.name.is_special()
2076 /// Returns `true` if the token is a keyword used in the language.
2077 pub fn is_used_keyword(self) -> bool {
2078 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2079 self.name.is_used_keyword_always()
2080 || self.name.is_used_keyword_conditional(|| self.span.edition())
2083 /// Returns `true` if the token is a keyword reserved for possible future use.
2084 pub fn is_unused_keyword(self) -> bool {
2085 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2086 self.name.is_unused_keyword_always()
2087 || self.name.is_unused_keyword_conditional(|| self.span.edition())
2090 /// Returns `true` if the token is either a special identifier or a keyword.
2091 pub fn is_reserved(self) -> bool {
2092 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2093 self.name.is_reserved(|| self.span.edition())
2096 /// A keyword or reserved identifier that can be used as a path segment.
2097 pub fn is_path_segment_keyword(self) -> bool {
2098 self.name.is_path_segment_keyword()
2101 /// We see this identifier in a normal identifier position, like variable name or a type.
2102 /// How was it written originally? Did it use the raw form? Let's try to guess.
2103 pub fn is_raw_guess(self) -> bool {
2104 self.name.can_be_raw() && self.is_reserved()