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,
964 native_link_modifiers,
965 native_link_modifiers_as_needed,
966 native_link_modifiers_bundle,
967 native_link_modifiers_verbatim,
968 native_link_modifiers_whole_archive,
1005 no_implicit_prelude,
1017 non_exhaustive_omitted_patterns_lint,
1028 object_safe_for_dispatch,
1031 omit_gdb_pretty_printer_section,
1040 optin_builtin_traits,
1048 overlapping_marker_traits,
1056 panic_cannot_unwind,
1061 panic_implementation,
1077 pattern_parentheses,
1080 platform_intrinsics,
1089 post_dash_lto: "post-lto",
1090 powerpc_target_feature,
1095 pre_dash_lto: "pre-lto",
1096 precise_pointer_size_matching,
1100 prefetch_read_instruction,
1101 prefetch_write_data,
1102 prefetch_write_instruction,
1110 proc_dash_macro: "proc-macro",
1112 proc_macro_attribute,
1117 proc_macro_internals,
1119 proc_macro_non_items,
1120 proc_macro_path_invoc,
1129 ptr_offset_from_unsigned,
1138 quad_precision_float,
1141 range_inclusive_new,
1146 re_rebalance_coherence,
1149 read_enum_variant_arg,
1157 reexport_test_harness_main,
1158 ref_unwind_safe_trait,
1175 relaxed_struct_unsize,
1188 return_position_impl_trait_in_trait,
1192 riscv_target_feature,
1211 rust_eh_catch_typeinfo,
1212 rust_eh_personality,
1215 rustc_allocator_zeroed,
1216 rustc_allow_const_fn_unstable,
1217 rustc_allow_incoherent_impl,
1218 rustc_allowed_through_unstable_modules,
1221 rustc_builtin_macro,
1222 rustc_capture_analysis,
1224 rustc_coherence_is_core,
1226 rustc_const_unstable,
1227 rustc_conversion_suggestion,
1230 rustc_default_body_unstable,
1231 rustc_deny_explicit_impl,
1232 rustc_diagnostic_item,
1233 rustc_diagnostic_macros,
1235 rustc_do_not_const_check,
1237 rustc_dump_env_program_clauses,
1238 rustc_dump_program_clauses,
1239 rustc_dump_user_substs,
1241 rustc_effective_visibility,
1243 rustc_evaluate_where_clauses,
1244 rustc_expected_cgu_reuse,
1245 rustc_has_incoherent_inherent_impls,
1246 rustc_if_this_changed,
1247 rustc_inherit_overflow_checks,
1248 rustc_insignificant_dtor,
1250 rustc_layout_scalar_valid_range_end,
1251 rustc_layout_scalar_valid_range_start,
1252 rustc_legacy_const_generics,
1253 rustc_lint_diagnostics,
1254 rustc_lint_opt_deny_field_access,
1256 rustc_lint_query_instability,
1257 rustc_macro_transparency,
1260 rustc_must_implement_one_of,
1261 rustc_nonnull_optimization_guaranteed,
1263 rustc_object_lifetime_default,
1264 rustc_on_unimplemented,
1267 rustc_partition_codegened,
1268 rustc_partition_reused,
1269 rustc_pass_by_value,
1271 rustc_peek_definite_init,
1272 rustc_peek_liveness,
1273 rustc_peek_maybe_init,
1274 rustc_peek_maybe_uninit,
1275 rustc_polymorphize_error,
1277 rustc_proc_macro_decls,
1281 rustc_reservation_impl,
1282 rustc_safe_intrinsic,
1284 rustc_skip_array_during_method_dispatch,
1285 rustc_specialization_trait,
1286 rustc_std_internal_symbol,
1287 rustc_strict_coherence,
1290 rustc_then_this_would_need,
1291 rustc_trivial_field_reads,
1292 rustc_unsafe_specialization_marker,
1296 rustdoc_missing_doc_code_examples,
1298 rvalue_static_promotion,
1343 simd_from_exposed_addr,
1356 simd_reduce_add_ordered,
1357 simd_reduce_add_unordered,
1362 simd_reduce_max_nanless,
1364 simd_reduce_min_nanless,
1365 simd_reduce_mul_ordered,
1366 simd_reduce_mul_unordered,
1371 simd_saturating_add,
1372 simd_saturating_sub,
1375 simd_select_bitmask,
1403 sse4a_target_feature,
1414 std_panic_2015_macro,
1417 stmt_expr_attributes,
1418 stop_after_dataflow,
1421 str_split_whitespace,
1426 string_deref_patterns,
1428 struct_field_attributes,
1451 target_has_atomic_equal_alignment,
1452 target_has_atomic_load_store,
1454 target_pointer_width,
1455 target_thread_local,
1460 termination_trait_test,
1463 test_accepted_feature,
1465 test_removed_feature,
1472 thumb_mode: "thumb-mode",
1503 type_alias_enum_variants,
1504 type_alias_impl_trait,
1507 type_changing_struct_update,
1517 unaligned_volatile_load,
1518 unaligned_volatile_store,
1527 underscore_const_names,
1529 underscore_lifetimes,
1531 unimplemented_macro,
1533 universal_impl_trait,
1541 unreachable_2015_macro,
1544 unreachable_display,
1546 unrestricted_attribute_tokens,
1547 unsafe_block_in_unsafe_fn,
1549 unsafe_no_drop_flag,
1550 unsafe_pin_internals,
1554 unsized_tuple_coercion,
1556 unstable_location_reason_default: "this crate is being loaded from the sysroot, an \
1557 unstable location; did you mean to load this crate \
1558 from crates.io via `Cargo.toml` instead?",
1588 visible_private_types,
1590 volatile_copy_memory,
1591 volatile_copy_nonoverlapping_memory,
1593 volatile_set_memory,
1602 wasm_target_feature,
1607 with_negative_coherence,
1619 yeet_desugar_details,
1626 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1634 /// Constructs a new identifier from a symbol and a span.
1635 pub const fn new(name: Symbol, span: Span) -> Ident {
1636 Ident { name, span }
1639 /// Constructs a new identifier with a dummy span.
1641 pub const fn with_dummy_span(name: Symbol) -> Ident {
1642 Ident::new(name, DUMMY_SP)
1646 pub fn empty() -> Ident {
1647 Ident::with_dummy_span(kw::Empty)
1650 /// Maps a string to an identifier with a dummy span.
1651 pub fn from_str(string: &str) -> Ident {
1652 Ident::with_dummy_span(Symbol::intern(string))
1655 /// Maps a string and a span to an identifier.
1656 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1657 Ident::new(Symbol::intern(string), span)
1660 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1661 pub fn with_span_pos(self, span: Span) -> Ident {
1662 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1665 pub fn without_first_quote(self) -> Ident {
1666 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1669 /// "Normalize" ident for use in comparisons using "item hygiene".
1670 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1671 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1672 /// different macro 2.0 macros.
1673 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1674 pub fn normalize_to_macros_2_0(self) -> Ident {
1675 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1678 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1679 /// Identifiers with same string value become same if they came from the same non-transparent
1680 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1681 /// non-transparent macros.
1682 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1684 pub fn normalize_to_macro_rules(self) -> Ident {
1685 Ident::new(self.name, self.span.normalize_to_macro_rules())
1688 /// Access the underlying string. This is a slowish operation because it
1689 /// requires locking the symbol interner.
1691 /// Note that the lifetime of the return value is a lie. See
1692 /// `Symbol::as_str()` for details.
1693 pub fn as_str(&self) -> &str {
1698 impl PartialEq for Ident {
1700 fn eq(&self, rhs: &Self) -> bool {
1701 self.name == rhs.name && self.span.eq_ctxt(rhs.span)
1705 impl Hash for Ident {
1706 fn hash<H: Hasher>(&self, state: &mut H) {
1707 self.name.hash(state);
1708 self.span.ctxt().hash(state);
1712 impl fmt::Debug for Ident {
1713 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1714 fmt::Display::fmt(self, f)?;
1715 fmt::Debug::fmt(&self.span.ctxt(), f)
1719 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1720 /// to printing the original identifier token written in source code (`token_to_string`),
1721 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1722 impl fmt::Display for Ident {
1723 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1724 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1728 /// The most general type to print identifiers.
1730 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1731 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1732 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1733 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1734 /// hygiene data, most importantly name of the crate it refers to.
1735 /// As a result we print `$crate` as `crate` if it refers to the local crate
1736 /// and as `::other_crate_name` if it refers to some other crate.
1737 /// Note, that this is only done if the ident token is printed from inside of AST pretty-printing,
1738 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1739 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1740 /// done for a token stream or a single token.
1741 pub struct IdentPrinter {
1744 /// Span used for retrieving the crate name to which `$crate` refers to,
1745 /// if this field is `None` then the `$crate` conversion doesn't happen.
1746 convert_dollar_crate: Option<Span>,
1750 /// The most general `IdentPrinter` constructor. Do not use this.
1751 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1752 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1755 /// This implementation is supposed to be used when printing identifiers
1756 /// as a part of pretty-printing for larger AST pieces.
1757 /// Do not use this either.
1758 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1759 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1763 impl fmt::Display for IdentPrinter {
1764 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1767 } else if self.symbol == kw::DollarCrate {
1768 if let Some(span) = self.convert_dollar_crate {
1769 let converted = span.ctxt().dollar_crate_name();
1770 if !converted.is_path_segment_keyword() {
1773 return fmt::Display::fmt(&converted, f);
1776 fmt::Display::fmt(&self.symbol, f)
1780 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1782 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1783 // `ModernIdent` struct and use that as well.
1784 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1785 pub struct MacroRulesNormalizedIdent(Ident);
1787 impl MacroRulesNormalizedIdent {
1788 pub fn new(ident: Ident) -> Self {
1789 Self(ident.normalize_to_macro_rules())
1793 impl fmt::Debug for MacroRulesNormalizedIdent {
1794 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1795 fmt::Debug::fmt(&self.0, f)
1799 impl fmt::Display for MacroRulesNormalizedIdent {
1800 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1801 fmt::Display::fmt(&self.0, f)
1805 /// An interned string.
1807 /// Internally, a `Symbol` is implemented as an index, and all operations
1808 /// (including hashing, equality, and ordering) operate on that index. The use
1809 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1810 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1812 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1813 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1814 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1815 pub struct Symbol(SymbolIndex);
1817 rustc_index::newtype_index! {
1818 struct SymbolIndex {}
1822 const fn new(n: u32) -> Self {
1823 Symbol(SymbolIndex::from_u32(n))
1826 /// for use in Decoder only
1827 pub fn new_from_decoded(n: u32) -> Self {
1831 /// Maps a string to its interned representation.
1832 pub fn intern(string: &str) -> Self {
1833 with_session_globals(|session_globals| session_globals.symbol_interner.intern(string))
1836 /// Access the underlying string. This is a slowish operation because it
1837 /// requires locking the symbol interner.
1839 /// Note that the lifetime of the return value is a lie. It's not the same
1840 /// as `&self`, but actually tied to the lifetime of the underlying
1841 /// interner. Interners are long-lived, and there are very few of them, and
1842 /// this function is typically used for short-lived things, so in practice
1843 /// it works out ok.
1844 pub fn as_str(&self) -> &str {
1845 with_session_globals(|session_globals| unsafe {
1846 std::mem::transmute::<&str, &str>(session_globals.symbol_interner.get(*self))
1850 pub fn as_u32(self) -> u32 {
1854 pub fn is_empty(self) -> bool {
1858 /// This method is supposed to be used in error messages, so it's expected to be
1859 /// identical to printing the original identifier token written in source code
1860 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1861 /// or edition, so we have to guess the rawness using the global edition.
1862 pub fn to_ident_string(self) -> String {
1863 Ident::with_dummy_span(self).to_string()
1867 impl fmt::Debug for Symbol {
1868 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1869 fmt::Debug::fmt(self.as_str(), f)
1873 impl fmt::Display for Symbol {
1874 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1875 fmt::Display::fmt(self.as_str(), f)
1879 // takes advantage of `str::to_string` specialization
1880 impl ToString for Symbol {
1881 fn to_string(&self) -> String {
1882 self.as_str().to_string()
1886 impl<S: Encoder> Encodable<S> for Symbol {
1887 default fn encode(&self, s: &mut S) {
1888 s.emit_str(self.as_str());
1892 impl<D: Decoder> Decodable<D> for Symbol {
1894 default fn decode(d: &mut D) -> Symbol {
1895 Symbol::intern(d.read_str())
1899 impl<CTX> HashStable<CTX> for Symbol {
1901 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1902 self.as_str().hash_stable(hcx, hasher);
1906 impl<CTX> ToStableHashKey<CTX> for Symbol {
1907 type KeyType = String;
1909 fn to_stable_hash_key(&self, _: &CTX) -> String {
1910 self.as_str().to_string()
1915 pub(crate) struct Interner(Lock<InternerInner>);
1917 // The `&'static str`s in this type actually point into the arena.
1919 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1920 // found that to regress performance up to 2% in some cases. This might be
1921 // revisited after further improvements to `indexmap`.
1923 // This type is private to prevent accidentally constructing more than one
1924 // `Interner` on the same thread, which makes it easy to mix up `Symbol`s
1925 // between `Interner`s.
1927 struct InternerInner {
1928 arena: DroplessArena,
1929 names: FxHashMap<&'static str, Symbol>,
1930 strings: Vec<&'static str>,
1934 fn prefill(init: &[&'static str]) -> Self {
1935 Interner(Lock::new(InternerInner {
1936 strings: init.into(),
1937 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1938 ..Default::default()
1943 fn intern(&self, string: &str) -> Symbol {
1944 let mut inner = self.0.lock();
1945 if let Some(&name) = inner.names.get(string) {
1949 let name = Symbol::new(inner.strings.len() as u32);
1951 // SAFETY: we convert from `&str` to `&[u8]`, clone it into the arena,
1952 // and immediately convert the clone back to `&[u8], all because there
1953 // is no `inner.arena.alloc_str()` method. This is clearly safe.
1955 unsafe { str::from_utf8_unchecked(inner.arena.alloc_slice(string.as_bytes())) };
1957 // SAFETY: we can extend the arena allocation to `'static` because we
1958 // only access these while the arena is still alive.
1959 let string: &'static str = unsafe { &*(string as *const str) };
1960 inner.strings.push(string);
1962 // This second hash table lookup can be avoided by using `RawEntryMut`,
1963 // but this code path isn't hot enough for it to be worth it. See
1964 // #91445 for details.
1965 inner.names.insert(string, name);
1969 // Get the symbol as a string. `Symbol::as_str()` should be used in
1970 // preference to this function.
1971 fn get(&self, symbol: Symbol) -> &str {
1972 self.0.lock().strings[symbol.0.as_usize()]
1976 // This module has a very short name because it's used a lot.
1977 /// This module contains all the defined keyword `Symbol`s.
1979 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1980 /// For example `kw::Loop` or `kw::Break`.
1982 pub use super::kw_generated::*;
1985 // This module has a very short name because it's used a lot.
1986 /// This module contains all the defined non-keyword `Symbol`s.
1988 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1989 /// For example `sym::rustfmt` or `sym::u8`.
1994 pub use super::sym_generated::*;
1996 // Used from a macro in `librustc_feature/accepted.rs`
1997 pub use super::kw::MacroRules as macro_rules;
1999 /// Get the symbol for an integer.
2001 /// The first few non-negative integers each have a static symbol and therefore
2003 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
2004 if let Result::Ok(idx) = n.try_into() {
2006 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
2009 Symbol::intern(&n.to_string())
2014 fn is_special(self) -> bool {
2015 self <= kw::Underscore
2018 fn is_used_keyword_always(self) -> bool {
2019 self >= kw::As && self <= kw::While
2022 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
2023 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
2026 fn is_unused_keyword_always(self) -> bool {
2027 self >= kw::Abstract && self <= kw::Yield
2030 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
2031 self == kw::Try && edition() >= Edition::Edition2018
2034 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
2036 || self.is_used_keyword_always()
2037 || self.is_unused_keyword_always()
2038 || self.is_used_keyword_conditional(edition)
2039 || self.is_unused_keyword_conditional(edition)
2042 /// A keyword or reserved identifier that can be used as a path segment.
2043 pub fn is_path_segment_keyword(self) -> bool {
2045 || self == kw::SelfLower
2046 || self == kw::SelfUpper
2047 || self == kw::Crate
2048 || self == kw::PathRoot
2049 || self == kw::DollarCrate
2052 /// Returns `true` if the symbol is `true` or `false`.
2053 pub fn is_bool_lit(self) -> bool {
2054 self == kw::True || self == kw::False
2057 /// Returns `true` if this symbol can be a raw identifier.
2058 pub fn can_be_raw(self) -> bool {
2059 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
2062 /// Is this symbol was interned in compiler's `symbols!` macro
2063 pub fn is_preinterned(self) -> bool {
2064 self.as_u32() < PREINTERNED_SYMBOLS_COUNT
2069 /// Returns `true` for reserved identifiers used internally for elided lifetimes,
2070 /// unnamed method parameters, crate root module, error recovery etc.
2071 pub fn is_special(self) -> bool {
2072 self.name.is_special()
2075 /// Returns `true` if the token is a keyword used in the language.
2076 pub fn is_used_keyword(self) -> bool {
2077 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2078 self.name.is_used_keyword_always()
2079 || self.name.is_used_keyword_conditional(|| self.span.edition())
2082 /// Returns `true` if the token is a keyword reserved for possible future use.
2083 pub fn is_unused_keyword(self) -> bool {
2084 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2085 self.name.is_unused_keyword_always()
2086 || self.name.is_unused_keyword_conditional(|| self.span.edition())
2089 /// Returns `true` if the token is either a special identifier or a keyword.
2090 pub fn is_reserved(self) -> bool {
2091 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2092 self.name.is_reserved(|| self.span.edition())
2095 /// A keyword or reserved identifier that can be used as a path segment.
2096 pub fn is_path_segment_keyword(self) -> bool {
2097 self.name.is_path_segment_keyword()
2100 /// We see this identifier in a normal identifier position, like variable name or a type.
2101 /// How was it written originally? Did it use the raw form? Let's try to guess.
2102 pub fn is_raw_guess(self) -> bool {
2103 self.name.can_be_raw() && self.is_reserved()