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
258 ProceduralMasqueradeDummyType,
286 SubdiagnosticMessage,
317 aarch64_target_feature,
318 aarch64_ver_target_feature,
322 abi_c_cmse_nonsecure_call,
324 abi_msp430_interrupt,
338 advanced_slice_patterns,
355 allow_internal_unsafe,
356 allow_internal_unstable,
362 anonymous_lifetime_in_impl_trait,
365 arbitrary_enum_discriminant,
366 arbitrary_self_types,
378 asm_experimental_arch,
386 assert_receiver_is_total_eq,
390 associated_const_equality,
392 associated_type_bounds,
393 associated_type_defaults,
406 augmented_assignments,
408 automatically_derived,
410 avx512_target_feature,
418 bind_by_move_pattern_guards,
430 borrowck_graphviz_format,
431 borrowck_graphviz_postflow,
432 borrowck_graphviz_preflow,
437 braced_empty_structs,
449 capture_disjoint_fields,
466 cfg_target_has_atomic,
467 cfg_target_has_atomic_equal_alignment,
468 cfg_target_has_atomic_load_store,
469 cfg_target_thread_local,
481 closure_lifetime_binder,
482 closure_to_fn_coercion,
483 closure_track_caller,
487 cmpxchg16b_target_feature,
488 cmse_nonsecure_entry,
496 compare_exchange_weak,
506 conservative_impl_trait,
510 const_compare_raw_pointers,
515 const_evaluatable_checked,
518 const_fn_floating_point_arithmetic,
519 const_fn_fn_ptr_basics,
520 const_fn_trait_bound,
526 const_generic_defaults,
528 const_generics_defaults,
531 const_in_array_repeat_expressions,
538 const_precise_live_drops,
540 const_raw_ptr_to_usize_cast,
543 const_trait_bound_opt_out,
560 core_panic_2015_macro,
571 crate_visibility_modifier,
572 crt_dash_static: "crt-static",
581 custom_inner_attributes,
582 custom_test_frameworks,
589 debug_assert_eq_macro,
591 debug_assert_ne_macro,
594 debug_struct_fields_finish,
597 debug_tuple_fields_finish,
602 default_alloc_error_handler,
603 default_lib_allocator,
604 default_method_body_is_const,
605 default_type_parameter_fallback,
607 delay_span_bug_from_inside_query,
611 deprecated_suggestion,
619 destructuring_assignment,
640 document_private_items,
642 dotdot_in_tuple_patterns,
643 dotdoteq_in_patterns,
651 dropck_parametricity,
663 emit_enum_variant_arg,
674 ermsb_target_feature,
678 exclusive_range_pattern,
679 exhaustive_integer_patterns,
688 explicit_generic_args_with_impl_trait,
691 extended_key_value_attributes,
692 extern_absolute_paths,
693 extern_crate_item_prelude,
717 field_init_shorthand,
724 float_to_int_unchecked,
757 from_size_align_unchecked,
774 generic_associated_types,
775 generic_associated_types_extended,
783 half_open_range_patterns,
785 hexagon_target_feature,
787 homogeneous_aggregate,
804 if_while_or_patterns,
806 impl_header_lifetime_elision,
809 impl_trait_in_bindings,
822 inclusive_range_syntax,
825 infer_outlives_requirements,
826 infer_static_outlives_requirements,
827 inherent_associated_types,
842 irrefutable_let_patterns,
846 issue_5723_bootstrap,
847 issue_tracker_base_url,
862 lazy_normalization_consts,
878 link_llvm_intrinsics,
899 macro_at_most_once_rep,
900 macro_attributes_in_derive_output,
903 macro_lifetime_matcher,
904 macro_literal_matcher,
917 match_beginning_vert,
918 match_default_bindings,
948 min_type_alias_impl_trait,
959 more_qualified_paths,
961 movbe_target_feature,
973 native_link_modifiers,
974 native_link_modifiers_as_needed,
975 native_link_modifiers_bundle,
976 native_link_modifiers_verbatim,
977 native_link_modifiers_whole_archive,
1003 no_implicit_prelude,
1015 non_exhaustive_omitted_patterns_lint,
1027 object_safe_for_dispatch,
1030 omit_gdb_pretty_printer_section,
1039 optin_builtin_traits,
1048 overlapping_marker_traits,
1060 panic_implementation,
1076 pattern_parentheses,
1079 platform_intrinsics,
1088 post_dash_lto: "post-lto",
1089 powerpc_target_feature,
1094 pre_dash_lto: "pre-lto",
1095 precise_pointer_size_matching,
1099 prefetch_read_instruction,
1100 prefetch_write_data,
1101 prefetch_write_instruction,
1109 proc_dash_macro: "proc-macro",
1111 proc_macro_attribute,
1112 proc_macro_def_site,
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,
1213 rust_eh_register_frames,
1214 rust_eh_unregister_frames,
1219 rustc_allocator_nounwind,
1220 rustc_allocator_zeroed,
1221 rustc_allow_const_fn_unstable,
1222 rustc_allow_incoherent_impl,
1223 rustc_allowed_through_unstable_modules,
1226 rustc_builtin_macro,
1227 rustc_capture_analysis,
1229 rustc_coherence_is_core,
1231 rustc_const_unstable,
1232 rustc_conversion_suggestion,
1235 rustc_default_body_unstable,
1236 rustc_diagnostic_item,
1237 rustc_diagnostic_macros,
1239 rustc_do_not_const_check,
1241 rustc_dump_env_program_clauses,
1242 rustc_dump_program_clauses,
1243 rustc_dump_user_substs,
1246 rustc_evaluate_where_clauses,
1247 rustc_expected_cgu_reuse,
1248 rustc_has_incoherent_inherent_impls,
1249 rustc_if_this_changed,
1250 rustc_inherit_overflow_checks,
1251 rustc_insignificant_dtor,
1253 rustc_layout_scalar_valid_range_end,
1254 rustc_layout_scalar_valid_range_start,
1255 rustc_legacy_const_generics,
1256 rustc_lint_diagnostics,
1257 rustc_lint_opt_deny_field_access,
1259 rustc_lint_query_instability,
1260 rustc_macro_transparency,
1263 rustc_must_implement_one_of,
1264 rustc_nonnull_optimization_guaranteed,
1265 rustc_object_lifetime_default,
1266 rustc_on_unimplemented,
1269 rustc_partition_codegened,
1270 rustc_partition_reused,
1271 rustc_pass_by_value,
1273 rustc_peek_definite_init,
1274 rustc_peek_liveness,
1275 rustc_peek_maybe_init,
1276 rustc_peek_maybe_uninit,
1277 rustc_polymorphize_error,
1279 rustc_proc_macro_decls,
1283 rustc_reservation_impl,
1285 rustc_skip_array_during_method_dispatch,
1286 rustc_specialization_trait,
1288 rustc_std_internal_symbol,
1289 rustc_strict_coherence,
1292 rustc_then_this_would_need,
1293 rustc_trivial_field_reads,
1294 rustc_unsafe_specialization_marker,
1298 rustdoc_missing_doc_code_examples,
1300 rvalue_static_promotion,
1345 simd_from_exposed_addr,
1358 simd_reduce_add_ordered,
1359 simd_reduce_add_unordered,
1364 simd_reduce_max_nanless,
1366 simd_reduce_min_nanless,
1367 simd_reduce_mul_ordered,
1368 simd_reduce_mul_unordered,
1373 simd_saturating_add,
1374 simd_saturating_sub,
1377 simd_select_bitmask,
1405 sse4a_target_feature,
1417 std_panic_2015_macro,
1420 stmt_expr_attributes,
1421 stop_after_dataflow,
1424 str_split_whitespace,
1431 struct_field_attributes,
1454 target_has_atomic_equal_alignment,
1455 target_has_atomic_load_store,
1457 target_pointer_width,
1458 target_target_vendor,
1459 target_thread_local,
1465 termination_trait_test,
1468 test_accepted_feature,
1470 test_removed_feature,
1478 thumb_mode: "thumb-mode",
1510 type_alias_enum_variants,
1511 type_alias_impl_trait,
1513 type_changing_struct_update,
1523 unaligned_volatile_load,
1524 unaligned_volatile_store,
1533 underscore_const_names,
1535 underscore_lifetimes,
1537 unimplemented_macro,
1539 universal_impl_trait,
1547 unreachable_2015_macro,
1549 unreachable_2021_macro,
1551 unreachable_display,
1553 unrestricted_attribute_tokens,
1554 unsafe_block_in_unsafe_fn,
1556 unsafe_no_drop_flag,
1557 unsafe_pin_internals,
1561 unsized_tuple_coercion,
1563 unstable_location_reason_default: "this crate is being loaded from the sysroot, an \
1564 unstable location; did you mean to load this crate \
1565 from crates.io via `Cargo.toml` instead?",
1568 unused_qualifications,
1596 visible_private_types,
1598 volatile_copy_memory,
1599 volatile_copy_nonoverlapping_memory,
1601 volatile_set_memory,
1610 wasm_target_feature,
1615 with_negative_coherence,
1627 yeet_desugar_details,
1634 #[derive(Copy, Clone, Eq, HashStable_Generic, Encodable, Decodable)]
1642 /// Constructs a new identifier from a symbol and a span.
1643 pub const fn new(name: Symbol, span: Span) -> Ident {
1644 Ident { name, span }
1647 /// Constructs a new identifier with a dummy span.
1649 pub const fn with_dummy_span(name: Symbol) -> Ident {
1650 Ident::new(name, DUMMY_SP)
1654 pub fn empty() -> Ident {
1655 Ident::with_dummy_span(kw::Empty)
1658 /// Maps a string to an identifier with a dummy span.
1659 pub fn from_str(string: &str) -> Ident {
1660 Ident::with_dummy_span(Symbol::intern(string))
1663 /// Maps a string and a span to an identifier.
1664 pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1665 Ident::new(Symbol::intern(string), span)
1668 /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1669 pub fn with_span_pos(self, span: Span) -> Ident {
1670 Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1673 pub fn without_first_quote(self) -> Ident {
1674 Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1677 /// "Normalize" ident for use in comparisons using "item hygiene".
1678 /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1679 /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1680 /// different macro 2.0 macros.
1681 /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1682 pub fn normalize_to_macros_2_0(self) -> Ident {
1683 Ident::new(self.name, self.span.normalize_to_macros_2_0())
1686 /// "Normalize" ident for use in comparisons using "local variable hygiene".
1687 /// Identifiers with same string value become same if they came from the same non-transparent
1688 /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1689 /// non-transparent macros.
1690 /// Technically, this operation strips all transparent marks from ident's syntactic context.
1691 pub fn normalize_to_macro_rules(self) -> Ident {
1692 Ident::new(self.name, self.span.normalize_to_macro_rules())
1695 /// Access the underlying string. This is a slowish operation because it
1696 /// requires locking the symbol interner.
1698 /// Note that the lifetime of the return value is a lie. See
1699 /// `Symbol::as_str()` for details.
1700 pub fn as_str(&self) -> &str {
1705 impl PartialEq for Ident {
1706 fn eq(&self, rhs: &Self) -> bool {
1707 self.name == rhs.name && self.span.eq_ctxt(rhs.span)
1711 impl Hash for Ident {
1712 fn hash<H: Hasher>(&self, state: &mut H) {
1713 self.name.hash(state);
1714 self.span.ctxt().hash(state);
1718 impl fmt::Debug for Ident {
1719 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1720 fmt::Display::fmt(self, f)?;
1721 fmt::Debug::fmt(&self.span.ctxt(), f)
1725 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1726 /// to printing the original identifier token written in source code (`token_to_string`),
1727 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1728 impl fmt::Display for Ident {
1729 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1730 fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1734 /// This is the most general way to print identifiers.
1735 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1736 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1737 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1738 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1739 /// hygiene data, most importantly name of the crate it refers to.
1740 /// As a result we print `$crate` as `crate` if it refers to the local crate
1741 /// and as `::other_crate_name` if it refers to some other crate.
1742 /// Note, that this is only done if the ident token is printed from inside of AST pretty-printing,
1743 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1744 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1745 /// done for a token stream or a single token.
1746 pub struct IdentPrinter {
1749 /// Span used for retrieving the crate name to which `$crate` refers to,
1750 /// if this field is `None` then the `$crate` conversion doesn't happen.
1751 convert_dollar_crate: Option<Span>,
1755 /// The most general `IdentPrinter` constructor. Do not use this.
1756 pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1757 IdentPrinter { symbol, is_raw, convert_dollar_crate }
1760 /// This implementation is supposed to be used when printing identifiers
1761 /// as a part of pretty-printing for larger AST pieces.
1762 /// Do not use this either.
1763 pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1764 IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1768 impl fmt::Display for IdentPrinter {
1769 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1772 } else if self.symbol == kw::DollarCrate {
1773 if let Some(span) = self.convert_dollar_crate {
1774 let converted = span.ctxt().dollar_crate_name();
1775 if !converted.is_path_segment_keyword() {
1778 return fmt::Display::fmt(&converted, f);
1781 fmt::Display::fmt(&self.symbol, f)
1785 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1787 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1788 // `ModernIdent` struct and use that as well.
1789 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1790 pub struct MacroRulesNormalizedIdent(Ident);
1792 impl MacroRulesNormalizedIdent {
1793 pub fn new(ident: Ident) -> Self {
1794 Self(ident.normalize_to_macro_rules())
1798 impl fmt::Debug for MacroRulesNormalizedIdent {
1799 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1800 fmt::Debug::fmt(&self.0, f)
1804 impl fmt::Display for MacroRulesNormalizedIdent {
1805 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1806 fmt::Display::fmt(&self.0, f)
1810 /// An interned string.
1812 /// Internally, a `Symbol` is implemented as an index, and all operations
1813 /// (including hashing, equality, and ordering) operate on that index. The use
1814 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1815 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1817 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1818 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1819 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1820 pub struct Symbol(SymbolIndex);
1822 rustc_index::newtype_index! {
1823 struct SymbolIndex { .. }
1827 const fn new(n: u32) -> Self {
1828 Symbol(SymbolIndex::from_u32(n))
1831 /// for use in Decoder only
1832 pub fn new_from_decoded(n: u32) -> Self {
1836 /// Maps a string to its interned representation.
1837 pub fn intern(string: &str) -> Self {
1838 with_session_globals(|session_globals| session_globals.symbol_interner.intern(string))
1841 /// Access the underlying string. This is a slowish operation because it
1842 /// requires locking the symbol interner.
1844 /// Note that the lifetime of the return value is a lie. It's not the same
1845 /// as `&self`, but actually tied to the lifetime of the underlying
1846 /// interner. Interners are long-lived, and there are very few of them, and
1847 /// this function is typically used for short-lived things, so in practice
1848 /// it works out ok.
1849 pub fn as_str(&self) -> &str {
1850 with_session_globals(|session_globals| unsafe {
1851 std::mem::transmute::<&str, &str>(session_globals.symbol_interner.get(*self))
1855 pub fn as_u32(self) -> u32 {
1859 pub fn is_empty(self) -> bool {
1863 /// This method is supposed to be used in error messages, so it's expected to be
1864 /// identical to printing the original identifier token written in source code
1865 /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1866 /// or edition, so we have to guess the rawness using the global edition.
1867 pub fn to_ident_string(self) -> String {
1868 Ident::with_dummy_span(self).to_string()
1872 impl fmt::Debug for Symbol {
1873 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1874 fmt::Debug::fmt(self.as_str(), f)
1878 impl fmt::Display for Symbol {
1879 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1880 fmt::Display::fmt(self.as_str(), f)
1884 impl<S: Encoder> Encodable<S> for Symbol {
1885 default fn encode(&self, s: &mut S) {
1886 s.emit_str(self.as_str());
1890 impl<D: Decoder> Decodable<D> for Symbol {
1892 default fn decode(d: &mut D) -> Symbol {
1893 Symbol::intern(&d.read_str())
1897 impl<CTX> HashStable<CTX> for Symbol {
1899 fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1900 self.as_str().hash_stable(hcx, hasher);
1904 impl<CTX> ToStableHashKey<CTX> for Symbol {
1905 type KeyType = String;
1907 fn to_stable_hash_key(&self, _: &CTX) -> String {
1908 self.as_str().to_string()
1913 pub(crate) struct Interner(Lock<InternerInner>);
1915 // The `&'static str`s in this type actually point into the arena.
1917 // The `FxHashMap`+`Vec` pair could be replaced by `FxIndexSet`, but #75278
1918 // found that to regress performance up to 2% in some cases. This might be
1919 // revisited after further improvements to `indexmap`.
1921 // This type is private to prevent accidentally constructing more than one
1922 // `Interner` on the same thread, which makes it easy to mix up `Symbol`s
1923 // between `Interner`s.
1925 struct InternerInner {
1926 arena: DroplessArena,
1927 names: FxHashMap<&'static str, Symbol>,
1928 strings: Vec<&'static str>,
1932 fn prefill(init: &[&'static str]) -> Self {
1933 Interner(Lock::new(InternerInner {
1934 strings: init.into(),
1935 names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1936 ..Default::default()
1941 fn intern(&self, string: &str) -> Symbol {
1942 let mut inner = self.0.lock();
1943 if let Some(&name) = inner.names.get(string) {
1947 let name = Symbol::new(inner.strings.len() as u32);
1949 // SAFETY: we convert from `&str` to `&[u8]`, clone it into the arena,
1950 // and immediately convert the clone back to `&[u8], all because there
1951 // is no `inner.arena.alloc_str()` method. This is clearly safe.
1953 unsafe { str::from_utf8_unchecked(inner.arena.alloc_slice(string.as_bytes())) };
1955 // SAFETY: we can extend the arena allocation to `'static` because we
1956 // only access these while the arena is still alive.
1957 let string: &'static str = unsafe { &*(string as *const str) };
1958 inner.strings.push(string);
1960 // This second hash table lookup can be avoided by using `RawEntryMut`,
1961 // but this code path isn't hot enough for it to be worth it. See
1962 // #91445 for details.
1963 inner.names.insert(string, name);
1967 // Get the symbol as a string. `Symbol::as_str()` should be used in
1968 // preference to this function.
1969 fn get(&self, symbol: Symbol) -> &str {
1970 self.0.lock().strings[symbol.0.as_usize()]
1974 // This module has a very short name because it's used a lot.
1975 /// This module contains all the defined keyword `Symbol`s.
1977 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1978 /// For example `kw::Loop` or `kw::Break`.
1980 pub use super::kw_generated::*;
1983 // This module has a very short name because it's used a lot.
1984 /// This module contains all the defined non-keyword `Symbol`s.
1986 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1987 /// For example `sym::rustfmt` or `sym::u8`.
1990 use std::convert::TryInto;
1993 pub use super::sym_generated::*;
1995 // Used from a macro in `librustc_feature/accepted.rs`
1996 pub use super::kw::MacroRules as macro_rules;
1998 /// Get the symbol for an integer.
2000 /// The first few non-negative integers each have a static symbol and therefore
2002 pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
2003 if let Result::Ok(idx) = n.try_into() {
2005 return Symbol::new(super::SYMBOL_DIGITS_BASE + idx as u32);
2008 Symbol::intern(&n.to_string())
2013 fn is_special(self) -> bool {
2014 self <= kw::Underscore
2017 fn is_used_keyword_always(self) -> bool {
2018 self >= kw::As && self <= kw::While
2021 fn is_used_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
2022 (self >= kw::Async && self <= kw::Dyn) && edition() >= Edition::Edition2018
2025 fn is_unused_keyword_always(self) -> bool {
2026 self >= kw::Abstract && self <= kw::Yield
2029 fn is_unused_keyword_conditional(self, edition: impl FnOnce() -> Edition) -> bool {
2030 self == kw::Try && edition() >= Edition::Edition2018
2033 pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
2035 || self.is_used_keyword_always()
2036 || self.is_unused_keyword_always()
2037 || self.is_used_keyword_conditional(edition)
2038 || self.is_unused_keyword_conditional(edition)
2041 /// A keyword or reserved identifier that can be used as a path segment.
2042 pub fn is_path_segment_keyword(self) -> bool {
2044 || self == kw::SelfLower
2045 || self == kw::SelfUpper
2046 || self == kw::Crate
2047 || self == kw::PathRoot
2048 || self == kw::DollarCrate
2051 /// Returns `true` if the symbol is `true` or `false`.
2052 pub fn is_bool_lit(self) -> bool {
2053 self == kw::True || self == kw::False
2056 /// Returns `true` if this symbol can be a raw identifier.
2057 pub fn can_be_raw(self) -> bool {
2058 self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
2061 /// Is this symbol was interned in compiler's `symbols!` macro
2062 pub fn is_preinterned(self) -> bool {
2063 self.as_u32() < PREINTERNED_SYMBOLS_COUNT
2068 // Returns `true` for reserved identifiers used internally for elided lifetimes,
2069 // unnamed method parameters, crate root module, error recovery etc.
2070 pub fn is_special(self) -> bool {
2071 self.name.is_special()
2074 /// Returns `true` if the token is a keyword used in the language.
2075 pub fn is_used_keyword(self) -> bool {
2076 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2077 self.name.is_used_keyword_always()
2078 || self.name.is_used_keyword_conditional(|| self.span.edition())
2081 /// Returns `true` if the token is a keyword reserved for possible future use.
2082 pub fn is_unused_keyword(self) -> bool {
2083 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2084 self.name.is_unused_keyword_always()
2085 || self.name.is_unused_keyword_conditional(|| self.span.edition())
2088 /// Returns `true` if the token is either a special identifier or a keyword.
2089 pub fn is_reserved(self) -> bool {
2090 // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
2091 self.name.is_reserved(|| self.span.edition())
2094 /// A keyword or reserved identifier that can be used as a path segment.
2095 pub fn is_path_segment_keyword(self) -> bool {
2096 self.name.is_path_segment_keyword()
2099 /// We see this identifier in a normal identifier position, like variable name or a type.
2100 /// How was it written originally? Did it use the raw form? Let's try to guess.
2101 pub fn is_raw_guess(self) -> bool {
2102 self.name.can_be_raw() && self.is_reserved()