src/librustc_span/symbol.rs

   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.
   4
   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_macros::{symbols, HashStable_Generic};
   9 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
  10 use rustc_serialize::{UseSpecializedDecodable, UseSpecializedEncodable};
  11
  12 use std::cmp::{Ord, PartialEq, PartialOrd};
  13 use std::fmt;
  14 use std::hash::{Hash, Hasher};
  15 use std::str;
  16
  17 use crate::{Span, DUMMY_SP, SESSION_GLOBALS};
  18
  19 #[cfg(test)]
  20 mod tests;
  21
  22 // The proc macro code for this is in `src/librustc_macros/src/symbols.rs`.
  23 symbols! {
  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.
  26     Keywords {
  27         // Special reserved identifiers used internally for elided lifetimes,
  28         // unnamed method parameters, crate root module, error recovery etc.
  29         Invalid:            "",
  30         PathRoot:           "{{root}}",
  31         DollarCrate:        "$crate",
  32         Underscore:         "_",
  33
  34         // Keywords that are used in stable Rust.
  35         As:                 "as",
  36         Break:              "break",
  37         Const:              "const",
  38         Continue:           "continue",
  39         Crate:              "crate",
  40         Else:               "else",
  41         Enum:               "enum",
  42         Extern:             "extern",
  43         False:              "false",
  44         Fn:                 "fn",
  45         For:                "for",
  46         If:                 "if",
  47         Impl:               "impl",
  48         In:                 "in",
  49         Let:                "let",
  50         Loop:               "loop",
  51         Match:              "match",
  52         Mod:                "mod",
  53         Move:               "move",
  54         Mut:                "mut",
  55         Pub:                "pub",
  56         Ref:                "ref",
  57         Return:             "return",
  58         SelfLower:          "self",
  59         SelfUpper:          "Self",
  60         Static:             "static",
  61         Struct:             "struct",
  62         Super:              "super",
  63         Trait:              "trait",
  64         True:               "true",
  65         Type:               "type",
  66         Unsafe:             "unsafe",
  67         Use:                "use",
  68         Where:              "where",
  69         While:              "while",
  70
  71         // Keywords that are used in unstable Rust or reserved for future use.
  72         Abstract:           "abstract",
  73         Become:             "become",
  74         Box:                "box",
  75         Do:                 "do",
  76         Final:              "final",
  77         Macro:              "macro",
  78         Override:           "override",
  79         Priv:               "priv",
  80         Typeof:             "typeof",
  81         Unsized:            "unsized",
  82         Virtual:            "virtual",
  83         Yield:              "yield",
  84
  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
  89
  90         // Edition-specific keywords that are used in unstable Rust or reserved for future use.
  91         Try:                "try", // >= 2018 Edition only
  92
  93         // Special lifetime names
  94         UnderscoreLifetime: "'_",
  95         StaticLifetime:     "'static",
  96
  97         // Weak keywords, have special meaning only in specific contexts.
  98         Auto:               "auto",
  99         Catch:              "catch",
 100         Default:            "default",
 101         MacroRules:         "macro_rules",
 102         Raw:                "raw",
 103         Union:              "union",
 104     }
 105
 106     // Pre-interned symbols that can be referred to with `rustc_span::sym::*`.
 107     //
 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".
 113     //
 114     // As well as the symbols listed, there are symbols for the the strings
 115     // "0", "1", ..., "9", which are accessible via `sym::integer`.
 116     //
 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`.
 121     //
 122     // There is currently no checking that all symbols are used; that would be
 123     // nice to have.
 124     Symbols {
 125         Alignment,
 126         Arc,
 127         Argument,
 128         ArgumentV1,
 129         Arguments,
 130         C,
 131         Center,
 132         Clone,
 133         Copy,
 134         Count,
 135         Debug,
 136         Decodable,
 137         Decoder,
 138         Default,
 139         Encodable,
 140         Encoder,
 141         Eq,
 142         Equal,
 143         Err,
 144         Error,
 145         FormatSpec,
 146         Formatter,
 147         From,
 148         Future,
 149         FxHashMap,
 150         FxHashSet,
 151         GlobalAlloc,
 152         Hash,
 153         HashMap,
 154         HashSet,
 155         Hasher,
 156         Implied,
 157         Input,
 158         IntoIterator,
 159         Is,
 160         ItemContext,
 161         Iterator,
 162         Layout,
 163         Left,
 164         LintPass,
 165         None,
 166         Ok,
 167         Option,
 168         Ord,
 169         Ordering,
 170         Output,
 171         Param,
 172         PartialEq,
 173         PartialOrd,
 174         Pending,
 175         Pin,
 176         Poll,
 177         ProcMacro,
 178         ProcMacroHack,
 179         ProceduralMasqueradeDummyType,
 180         Range,
 181         RangeFrom,
 182         RangeFull,
 183         RangeInclusive,
 184         RangeTo,
 185         RangeToInclusive,
 186         Rc,
 187         Ready,
 188         Result,
 189         Return,
 190         Right,
 191         RustcDecodable,
 192         RustcEncodable,
 193         Send,
 194         Some,
 195         StructuralEq,
 196         StructuralPartialEq,
 197         Sync,
 198         Target,
 199         Try,
 200         Ty,
 201         TyCtxt,
 202         TyKind,
 203         Unknown,
 204         Vec,
 205         Yield,
 206         _DECLS,
 207         _Self,
 208         __D,
 209         __H,
 210         __S,
 211         __next,
 212         __try_var,
 213         _d,
 214         _e,
 215         _task_context,
 216         aarch64_target_feature,
 217         abi,
 218         abi_amdgpu_kernel,
 219         abi_avr_interrupt,
 220         abi_efiapi,
 221         abi_msp430_interrupt,
 222         abi_ptx,
 223         abi_sysv64,
 224         abi_thiscall,
 225         abi_unadjusted,
 226         abi_vectorcall,
 227         abi_x86_interrupt,
 228         abort,
 229         aborts,
 230         add,
 231         add_assign,
 232         add_with_overflow,
 233         address,
 234         advanced_slice_patterns,
 235         adx_target_feature,
 236         alias,
 237         align,
 238         align_offset,
 239         alignstack,
 240         all,
 241         alloc,
 242         alloc_error_handler,
 243         alloc_layout,
 244         alloc_zeroed,
 245         allocator,
 246         allocator_internals,
 247         allow,
 248         allow_fail,
 249         allow_internal_unsafe,
 250         allow_internal_unstable,
 251         allow_internal_unstable_backcompat_hack,
 252         allowed,
 253         always,
 254         and,
 255         and_then,
 256         any,
 257         arbitrary_enum_discriminant,
 258         arbitrary_self_types,
 259         arith_offset,
 260         arm_target_feature,
 261         array,
 262         as_str,
 263         asm,
 264         assert,
 265         assert_inhabited,
 266         assert_receiver_is_total_eq,
 267         assert_uninit_valid,
 268         assert_zero_valid,
 269         associated_consts,
 270         associated_type_bounds,
 271         associated_type_defaults,
 272         associated_types,
 273         assume,
 274         assume_init,
 275         async_await,
 276         async_closure,
 277         atomics,
 278         att_syntax,
 279         attr,
 280         attr_literals,
 281         attributes,
 282         augmented_assignments,
 283         automatically_derived,
 284         avx512_target_feature,
 285         await_macro,
 286         bang,
 287         begin_panic,
 288         bench,
 289         bin,
 290         bind_by_move_pattern_guards,
 291         bindings_after_at,
 292         bitand,
 293         bitand_assign,
 294         bitor,
 295         bitor_assign,
 296         bitreverse,
 297         bitxor,
 298         bitxor_assign,
 299         block,
 300         bool,
 301         borrowck_graphviz_format,
 302         borrowck_graphviz_postflow,
 303         borrowck_graphviz_preflow,
 304         box_free,
 305         box_patterns,
 306         box_syntax,
 307         braced_empty_structs,
 308         breakpoint,
 309         bridge,
 310         bswap,
 311         c_variadic,
 312         call,
 313         call_mut,
 314         call_once,
 315         caller_location,
 316         cdylib,
 317         ceilf32,
 318         ceilf64,
 319         cfg,
 320         cfg_accessible,
 321         cfg_attr,
 322         cfg_attr_multi,
 323         cfg_doctest,
 324         cfg_sanitize,
 325         cfg_target_feature,
 326         cfg_target_has_atomic,
 327         cfg_target_thread_local,
 328         cfg_target_vendor,
 329         cfg_version,
 330         char,
 331         client,
 332         clippy,
 333         clone,
 334         clone_closures,
 335         clone_from,
 336         closure_to_fn_coercion,
 337         cmp,
 338         cmpxchg16b_target_feature,
 339         coerce_unsized,
 340         cold,
 341         column,
 342         compile_error,
 343         compiler_builtins,
 344         concat,
 345         concat_idents,
 346         conservative_impl_trait,
 347         console,
 348         const_compare_raw_pointers,
 349         const_constructor,
 350         const_eval_limit,
 351         const_extern_fn,
 352         const_fn,
 353         const_fn_transmute,
 354         const_fn_union,
 355         const_generics,
 356         const_if_match,
 357         const_in_array_repeat_expressions,
 358         const_indexing,
 359         const_let,
 360         const_loop,
 361         const_mut_refs,
 362         const_panic,
 363         const_precise_live_drops,
 364         const_ptr,
 365         const_raw_ptr_deref,
 366         const_raw_ptr_to_usize_cast,
 367         const_slice_ptr,
 368         const_trait_bound_opt_out,
 369         const_trait_impl,
 370         const_transmute,
 371         contents,
 372         context,
 373         convert,
 374         copy,
 375         copy_closures,
 376         copy_nonoverlapping,
 377         copysignf32,
 378         copysignf64,
 379         core,
 380         core_intrinsics,
 381         cosf32,
 382         cosf64,
 383         count_code_region,
 384         coverage_counter_add,
 385         coverage_counter_subtract,
 386         coverage_unreachable,
 387         crate_id,
 388         crate_in_paths,
 389         crate_local,
 390         crate_name,
 391         crate_type,
 392         crate_visibility_modifier,
 393         crt_dash_static: "crt-static",
 394         ctlz,
 395         ctlz_nonzero,
 396         ctpop,
 397         cttz,
 398         cttz_nonzero,
 399         custom_attribute,
 400         custom_derive,
 401         custom_inner_attributes,
 402         custom_test_frameworks,
 403         d,
 404         dead_code,
 405         dealloc,
 406         debug,
 407         debug_assertions,
 408         debug_struct,
 409         debug_trait,
 410         debug_trait_builder,
 411         debug_tuple,
 412         decl_macro,
 413         declare_lint_pass,
 414         decode,
 415         default_lib_allocator,
 416         default_type_parameter_fallback,
 417         default_type_params,
 418         delay_span_bug_from_inside_query,
 419         deny,
 420         deprecated,
 421         deref,
 422         deref_mut,
 423         derive,
 424         diagnostic,
 425         direct,
 426         discriminant_kind,
 427         discriminant_type,
 428         discriminant_value,
 429         dispatch_from_dyn,
 430         div,
 431         div_assign,
 432         doc,
 433         doc_alias,
 434         doc_cfg,
 435         doc_keyword,
 436         doc_masked,
 437         doc_spotlight,
 438         doctest,
 439         document_private_items,
 440         dotdot_in_tuple_patterns,
 441         dotdoteq_in_patterns,
 442         double_braced_closure: "{{closure}}",
 443         double_braced_constant: "{{constant}}",
 444         double_braced_constructor: "{{constructor}}",
 445         double_braced_crate: "{{crate}}",
 446         double_braced_impl: "{{impl}}",
 447         double_braced_misc: "{{misc}}",
 448         double_braced_opaque: "{{opaque}}",
 449         drop,
 450         drop_in_place,
 451         drop_types_in_const,
 452         dropck_eyepatch,
 453         dropck_parametricity,
 454         dylib,
 455         dyn_trait,
 456         eh_catch_typeinfo,
 457         eh_personality,
 458         emit_enum,
 459         emit_enum_variant,
 460         emit_enum_variant_arg,
 461         emit_struct,
 462         emit_struct_field,
 463         enable,
 464         enclosing_scope,
 465         encode,
 466         env,
 467         eq,
 468         err,
 469         exact_div,
 470         except,
 471         exchange_malloc,
 472         exclusive_range_pattern,
 473         exhaustive_integer_patterns,
 474         exhaustive_patterns,
 475         existential_type,
 476         exp2f32,
 477         exp2f64,
 478         expected,
 479         expf32,
 480         expf64,
 481         export_name,
 482         expr,
 483         extern_absolute_paths,
 484         extern_crate_item_prelude,
 485         extern_crate_self,
 486         extern_in_paths,
 487         extern_prelude,
 488         extern_types,
 489         external_doc,
 490         f,
 491         f16c_target_feature,
 492         f32,
 493         f32_runtime,
 494         f64,
 495         f64_runtime,
 496         fabsf32,
 497         fabsf64,
 498         fadd_fast,
 499         fdiv_fast,
 500         feature,
 501         ffi_const,
 502         ffi_pure,
 503         ffi_returns_twice,
 504         field,
 505         field_init_shorthand,
 506         file,
 507         fill,
 508         finish,
 509         flags,
 510         float_to_int_unchecked,
 511         floorf32,
 512         floorf64,
 513         fmaf32,
 514         fmaf64,
 515         fmt,
 516         fmt_internals,
 517         fmul_fast,
 518         fn_must_use,
 519         fn_mut,
 520         fn_once,
 521         fn_once_output,
 522         forbid,
 523         forget,
 524         format,
 525         format_args,
 526         format_args_capture,
 527         format_args_nl,
 528         freeze,
 529         frem_fast,
 530         from,
 531         from_desugaring,
 532         from_error,
 533         from_generator,
 534         from_method,
 535         from_ok,
 536         from_size_align_unchecked,
 537         from_trait,
 538         from_usize,
 539         fsub_fast,
 540         fundamental,
 541         future,
 542         future_trait,
 543         ge,
 544         gen_future,
 545         gen_kill,
 546         generator,
 547         generator_state,
 548         generators,
 549         generic_associated_types,
 550         generic_param_attrs,
 551         get_context,
 552         global_allocator,
 553         global_asm,
 554         globs,
 555         gt,
 556         half_open_range_patterns,
 557         hash,
 558         hexagon_target_feature,
 559         hidden,
 560         homogeneous_aggregate,
 561         html_favicon_url,
 562         html_logo_url,
 563         html_no_source,
 564         html_playground_url,
 565         html_root_url,
 566         i,
 567         i128,
 568         i128_type,
 569         i16,
 570         i32,
 571         i64,
 572         i8,
 573         ident,
 574         if_let,
 575         if_while_or_patterns,
 576         ignore,
 577         impl_header_lifetime_elision,
 578         impl_lint_pass,
 579         impl_trait_in_bindings,
 580         import_shadowing,
 581         in_band_lifetimes,
 582         include,
 583         include_bytes,
 584         include_str,
 585         inclusive_range_syntax,
 586         index,
 587         index_mut,
 588         infer_outlives_requirements,
 589         infer_static_outlives_requirements,
 590         inlateout,
 591         inline,
 592         inout,
 593         intel,
 594         into_iter,
 595         into_result,
 596         intrinsics,
 597         irrefutable_let_patterns,
 598         isize,
 599         issue,
 600         issue_5723_bootstrap,
 601         issue_tracker_base_url,
 602         item,
 603         item_like_imports,
 604         iter,
 605         keyword,
 606         kind,
 607         label,
 608         label_break_value,
 609         lang,
 610         lang_items,
 611         lateout,
 612         lazy_normalization_consts,
 613         le,
 614         let_chains,
 615         lhs,
 616         lib,
 617         libc,
 618         lifetime,
 619         likely,
 620         line,
 621         link,
 622         link_args,
 623         link_cfg,
 624         link_llvm_intrinsics,
 625         link_name,
 626         link_ordinal,
 627         link_section,
 628         linkage,
 629         lint_reasons,
 630         literal,
 631         llvm_asm,
 632         local_inner_macros,
 633         log10f32,
 634         log10f64,
 635         log2f32,
 636         log2f64,
 637         log_syntax,
 638         logf32,
 639         logf64,
 640         loop_break_value,
 641         lt,
 642         macro_at_most_once_rep,
 643         macro_escape,
 644         macro_export,
 645         macro_lifetime_matcher,
 646         macro_literal_matcher,
 647         macro_reexport,
 648         macro_use,
 649         macro_vis_matcher,
 650         macros_in_extern,
 651         main,
 652         managed_boxes,
 653         manually_drop,
 654         map,
 655         marker,
 656         marker_trait_attr,
 657         masked,
 658         match_beginning_vert,
 659         match_default_bindings,
 660         maxnumf32,
 661         maxnumf64,
 662         may_dangle,
 663         maybe_uninit,
 664         maybe_uninit_uninit,
 665         maybe_uninit_zeroed,
 666         mem_uninitialized,
 667         mem_zeroed,
 668         member_constraints,
 669         memory,
 670         message,
 671         meta,
 672         min_align_of,
 673         min_align_of_val,
 674         min_const_fn,
 675         min_const_unsafe_fn,
 676         min_specialization,
 677         minnumf32,
 678         minnumf64,
 679         mips_target_feature,
 680         mmx_target_feature,
 681         module,
 682         module_path,
 683         more_struct_aliases,
 684         movbe_target_feature,
 685         move_ref_pattern,
 686         move_val_init,
 687         mul,
 688         mul_assign,
 689         mul_with_overflow,
 690         must_use,
 691         mut_ptr,
 692         mut_slice_ptr,
 693         naked,
 694         naked_functions,
 695         name,
 696         ne,
 697         nearbyintf32,
 698         nearbyintf64,
 699         needs_allocator,
 700         needs_drop,
 701         needs_panic_runtime,
 702         neg,
 703         negate_unsigned,
 704         negative_impls,
 705         never,
 706         never_type,
 707         never_type_fallback,
 708         new,
 709         next,
 710         nll,
 711         no,
 712         no_builtins,
 713         no_core,
 714         no_crate_inject,
 715         no_debug,
 716         no_default_passes,
 717         no_implicit_prelude,
 718         no_inline,
 719         no_link,
 720         no_main,
 721         no_mangle,
 722         no_niche,
 723         no_sanitize,
 724         no_stack_check,
 725         no_start,
 726         no_std,
 727         nomem,
 728         non_ascii_idents,
 729         non_exhaustive,
 730         non_modrs_mods,
 731         none_error,
 732         nontemporal_store,
 733         nontrapping_dash_fptoint: "nontrapping-fptoint",
 734         noreturn,
 735         nostack,
 736         not,
 737         note,
 738         object_safe_for_dispatch,
 739         offset,
 740         omit_gdb_pretty_printer_section,
 741         on,
 742         on_unimplemented,
 743         oom,
 744         opaque,
 745         ops,
 746         opt_out_copy,
 747         optimize,
 748         optimize_attribute,
 749         optin_builtin_traits,
 750         option,
 751         option_env,
 752         option_type,
 753         options,
 754         or,
 755         or_patterns,
 756         other,
 757         out,
 758         overlapping_marker_traits,
 759         owned_box,
 760         packed,
 761         panic,
 762         panic_abort,
 763         panic_bounds_check,
 764         panic_handler,
 765         panic_impl,
 766         panic_implementation,
 767         panic_info,
 768         panic_location,
 769         panic_runtime,
 770         panic_unwind,
 771         param_attrs,
 772         parent_trait,
 773         partial_cmp,
 774         partial_ord,
 775         passes,
 776         pat,
 777         path,
 778         pattern_parentheses,
 779         phantom_data,
 780         pin,
 781         pinned,
 782         platform_intrinsics,
 783         plugin,
 784         plugin_registrar,
 785         plugins,
 786         pointer,
 787         poll,
 788         position,
 789         post_dash_lto: "post-lto",
 790         powerpc_target_feature,
 791         powf32,
 792         powf64,
 793         powif32,
 794         powif64,
 795         pre_dash_lto: "pre-lto",
 796         precise_pointer_size_matching,
 797         precision,
 798         pref_align_of,
 799         prefetch_read_data,
 800         prefetch_read_instruction,
 801         prefetch_write_data,
 802         prefetch_write_instruction,
 803         prelude,
 804         prelude_import,
 805         preserves_flags,
 806         primitive,
 807         proc_dash_macro: "proc-macro",
 808         proc_macro,
 809         proc_macro_attribute,
 810         proc_macro_def_site,
 811         proc_macro_derive,
 812         proc_macro_expr,
 813         proc_macro_gen,
 814         proc_macro_hygiene,
 815         proc_macro_internals,
 816         proc_macro_mod,
 817         proc_macro_non_items,
 818         proc_macro_path_invoc,
 819         profiler_builtins,
 820         profiler_runtime,
 821         ptr_guaranteed_eq,
 822         ptr_guaranteed_ne,
 823         ptr_offset_from,
 824         pub_restricted,
 825         pure,
 826         pushpop_unsafe,
 827         quad_precision_float,
 828         question_mark,
 829         quote,
 830         raw_dylib,
 831         raw_identifiers,
 832         raw_ref_op,
 833         re_rebalance_coherence,
 834         read_enum,
 835         read_enum_variant,
 836         read_enum_variant_arg,
 837         read_struct,
 838         read_struct_field,
 839         readonly,
 840         realloc,
 841         reason,
 842         receiver,
 843         recursion_limit,
 844         reexport_test_harness_main,
 845         reference,
 846         reflect,
 847         register_attr,
 848         register_tool,
 849         relaxed_adts,
 850         rem,
 851         rem_assign,
 852         repr,
 853         repr128,
 854         repr_align,
 855         repr_align_enum,
 856         repr_no_niche,
 857         repr_packed,
 858         repr_simd,
 859         repr_transparent,
 860         result,
 861         result_type,
 862         rhs,
 863         rintf32,
 864         rintf64,
 865         riscv_target_feature,
 866         rlib,
 867         rotate_left,
 868         rotate_right,
 869         roundf32,
 870         roundf64,
 871         rt,
 872         rtm_target_feature,
 873         rust,
 874         rust_2015_preview,
 875         rust_2018_preview,
 876         rust_begin_unwind,
 877         rust_eh_personality,
 878         rust_eh_register_frames,
 879         rust_eh_unregister_frames,
 880         rust_oom,
 881         rustc,
 882         rustc_allocator,
 883         rustc_allocator_nounwind,
 884         rustc_allow_const_fn_ptr,
 885         rustc_args_required_const,
 886         rustc_attrs,
 887         rustc_builtin_macro,
 888         rustc_clean,
 889         rustc_const_stable,
 890         rustc_const_unstable,
 891         rustc_conversion_suggestion,
 892         rustc_def_path,
 893         rustc_deprecated,
 894         rustc_diagnostic_item,
 895         rustc_diagnostic_macros,
 896         rustc_dirty,
 897         rustc_dummy,
 898         rustc_dump_env_program_clauses,
 899         rustc_dump_program_clauses,
 900         rustc_dump_user_substs,
 901         rustc_error,
 902         rustc_expected_cgu_reuse,
 903         rustc_if_this_changed,
 904         rustc_inherit_overflow_checks,
 905         rustc_layout,
 906         rustc_layout_scalar_valid_range_end,
 907         rustc_layout_scalar_valid_range_start,
 908         rustc_macro_transparency,
 909         rustc_mir,
 910         rustc_nonnull_optimization_guaranteed,
 911         rustc_object_lifetime_default,
 912         rustc_on_unimplemented,
 913         rustc_outlives,
 914         rustc_paren_sugar,
 915         rustc_partition_codegened,
 916         rustc_partition_reused,
 917         rustc_peek,
 918         rustc_peek_definite_init,
 919         rustc_peek_indirectly_mutable,
 920         rustc_peek_liveness,
 921         rustc_peek_maybe_init,
 922         rustc_peek_maybe_uninit,
 923         rustc_polymorphize_error,
 924         rustc_private,
 925         rustc_proc_macro_decls,
 926         rustc_promotable,
 927         rustc_regions,
 928         rustc_reservation_impl,
 929         rustc_serialize,
 930         rustc_specialization_trait,
 931         rustc_stable,
 932         rustc_std_internal_symbol,
 933         rustc_symbol_name,
 934         rustc_synthetic,
 935         rustc_test_marker,
 936         rustc_then_this_would_need,
 937         rustc_unsafe_specialization_marker,
 938         rustc_variance,
 939         rustfmt,
 940         rvalue_static_promotion,
 941         sanitize,
 942         sanitizer_runtime,
 943         saturating_add,
 944         saturating_sub,
 945         self_in_typedefs,
 946         self_struct_ctor,
 947         semitransparent,
 948         send_trait,
 949         shl,
 950         shl_assign,
 951         should_panic,
 952         shr,
 953         shr_assign,
 954         simd,
 955         simd_add,
 956         simd_and,
 957         simd_bitmask,
 958         simd_cast,
 959         simd_ceil,
 960         simd_div,
 961         simd_eq,
 962         simd_extract,
 963         simd_fabs,
 964         simd_fcos,
 965         simd_fexp,
 966         simd_fexp2,
 967         simd_ffi,
 968         simd_flog,
 969         simd_flog10,
 970         simd_flog2,
 971         simd_floor,
 972         simd_fma,
 973         simd_fmax,
 974         simd_fmin,
 975         simd_fpow,
 976         simd_fpowi,
 977         simd_fsin,
 978         simd_fsqrt,
 979         simd_gather,
 980         simd_ge,
 981         simd_gt,
 982         simd_insert,
 983         simd_le,
 984         simd_lt,
 985         simd_mul,
 986         simd_ne,
 987         simd_or,
 988         simd_reduce_add_ordered,
 989         simd_reduce_add_unordered,
 990         simd_reduce_all,
 991         simd_reduce_and,
 992         simd_reduce_any,
 993         simd_reduce_max,
 994         simd_reduce_max_nanless,
 995         simd_reduce_min,
 996         simd_reduce_min_nanless,
 997         simd_reduce_mul_ordered,
 998         simd_reduce_mul_unordered,
 999         simd_reduce_or,
1000         simd_reduce_xor,
1001         simd_rem,
1002         simd_saturating_add,
1003         simd_saturating_sub,
1004         simd_scatter,
1005         simd_select,
1006         simd_select_bitmask,
1007         simd_shl,
1008         simd_shr,
1009         simd_sub,
1010         simd_xor,
1011         since,
1012         sinf32,
1013         sinf64,
1014         size,
1015         size_of,
1016         size_of_val,
1017         sized,
1018         slice,
1019         slice_alloc,
1020         slice_patterns,
1021         slice_u8,
1022         slice_u8_alloc,
1023         slicing_syntax,
1024         soft,
1025         specialization,
1026         speed,
1027         spotlight,
1028         sqrtf32,
1029         sqrtf64,
1030         sse4a_target_feature,
1031         stable,
1032         staged_api,
1033         start,
1034         state,
1035         static_in_const,
1036         static_nobundle,
1037         static_recursion,
1038         staticlib,
1039         std,
1040         std_inject,
1041         stmt,
1042         stmt_expr_attributes,
1043         stop_after_dataflow,
1044         str,
1045         str_alloc,
1046         string_type,
1047         stringify,
1048         struct_field_attributes,
1049         struct_inherit,
1050         struct_variant,
1051         structural_match,
1052         structural_peq,
1053         structural_teq,
1054         sty,
1055         sub,
1056         sub_assign,
1057         sub_with_overflow,
1058         suggestion,
1059         sym,
1060         sync,
1061         sync_trait,
1062         target_arch,
1063         target_endian,
1064         target_env,
1065         target_family,
1066         target_feature,
1067         target_feature_11,
1068         target_has_atomic,
1069         target_has_atomic_load_store,
1070         target_os,
1071         target_pointer_width,
1072         target_target_vendor,
1073         target_thread_local,
1074         target_vendor,
1075         task,
1076         tbm_target_feature,
1077         termination,
1078         termination_trait,
1079         termination_trait_test,
1080         test,
1081         test_2018_feature,
1082         test_accepted_feature,
1083         test_case,
1084         test_removed_feature,
1085         test_runner,
1086         then_with,
1087         thread,
1088         thread_local,
1089         tool_attributes,
1090         tool_lints,
1091         trace_macros,
1092         track_caller,
1093         trait_alias,
1094         transmute,
1095         transparent,
1096         transparent_enums,
1097         transparent_unions,
1098         trivial_bounds,
1099         truncf32,
1100         truncf64,
1101         try_blocks,
1102         try_trait,
1103         tt,
1104         tuple,
1105         tuple_indexing,
1106         two_phase,
1107         ty,
1108         type_alias_enum_variants,
1109         type_alias_impl_trait,
1110         type_ascription,
1111         type_id,
1112         type_length_limit,
1113         type_macros,
1114         type_name,
1115         u128,
1116         u16,
1117         u32,
1118         u64,
1119         u8,
1120         unaligned_volatile_load,
1121         unaligned_volatile_store,
1122         unboxed_closures,
1123         unchecked_add,
1124         unchecked_div,
1125         unchecked_mul,
1126         unchecked_rem,
1127         unchecked_shl,
1128         unchecked_shr,
1129         unchecked_sub,
1130         underscore_const_names,
1131         underscore_imports,
1132         underscore_lifetimes,
1133         uniform_paths,
1134         unit,
1135         universal_impl_trait,
1136         unix,
1137         unlikely,
1138         unmarked_api,
1139         unpin,
1140         unreachable,
1141         unreachable_code,
1142         unrestricted_attribute_tokens,
1143         unsafe_block_in_unsafe_fn,
1144         unsafe_cell,
1145         unsafe_no_drop_flag,
1146         unsize,
1147         unsized_locals,
1148         unsized_tuple_coercion,
1149         unstable,
1150         untagged_unions,
1151         unused_qualifications,
1152         unwind,
1153         unwind_attributes,
1154         unwrap_or,
1155         use_extern_macros,
1156         use_nested_groups,
1157         used,
1158         usize,
1159         v1,
1160         va_arg,
1161         va_copy,
1162         va_end,
1163         va_list,
1164         va_start,
1165         val,
1166         var,
1167         variant_count,
1168         vec,
1169         vec_type,
1170         version,
1171         vis,
1172         visible_private_types,
1173         volatile,
1174         volatile_copy_memory,
1175         volatile_copy_nonoverlapping_memory,
1176         volatile_load,
1177         volatile_set_memory,
1178         volatile_store,
1179         warn,
1180         wasm_import_module,
1181         wasm_target_feature,
1182         while_let,
1183         width,
1184         windows,
1185         windows_subsystem,
1186         wrapping_add,
1187         wrapping_mul,
1188         wrapping_sub,
1189         write_bytes,
1190     }
1191 }
1192
1193 #[derive(Copy, Clone, Eq, HashStable_Generic)]
1194 pub struct Ident {
1195     pub name: Symbol,
1196     pub span: Span,
1197 }
1198
1199 impl Ident {
1200     #[inline]
1201     /// Constructs a new identifier from a symbol and a span.
1202     pub const fn new(name: Symbol, span: Span) -> Ident {
1203         Ident { name, span }
1204     }
1205
1206     /// Constructs a new identifier with a dummy span.
1207     #[inline]
1208     pub const fn with_dummy_span(name: Symbol) -> Ident {
1209         Ident::new(name, DUMMY_SP)
1210     }
1211
1212     #[inline]
1213     pub fn invalid() -> Ident {
1214         Ident::with_dummy_span(kw::Invalid)
1215     }
1216
1217     /// Maps a string to an identifier with a dummy span.
1218     pub fn from_str(string: &str) -> Ident {
1219         Ident::with_dummy_span(Symbol::intern(string))
1220     }
1221
1222     /// Maps a string and a span to an identifier.
1223     pub fn from_str_and_span(string: &str, span: Span) -> Ident {
1224         Ident::new(Symbol::intern(string), span)
1225     }
1226
1227     /// Replaces `lo` and `hi` with those from `span`, but keep hygiene context.
1228     pub fn with_span_pos(self, span: Span) -> Ident {
1229         Ident::new(self.name, span.with_ctxt(self.span.ctxt()))
1230     }
1231
1232     pub fn without_first_quote(self) -> Ident {
1233         Ident::new(Symbol::intern(self.as_str().trim_start_matches('\'')), self.span)
1234     }
1235
1236     /// "Normalize" ident for use in comparisons using "item hygiene".
1237     /// Identifiers with same string value become same if they came from the same macro 2.0 macro
1238     /// (e.g., `macro` item, but not `macro_rules` item) and stay different if they came from
1239     /// different macro 2.0 macros.
1240     /// Technically, this operation strips all non-opaque marks from ident's syntactic context.
1241     pub fn normalize_to_macros_2_0(self) -> Ident {
1242         Ident::new(self.name, self.span.normalize_to_macros_2_0())
1243     }
1244
1245     /// "Normalize" ident for use in comparisons using "local variable hygiene".
1246     /// Identifiers with same string value become same if they came from the same non-transparent
1247     /// macro (e.g., `macro` or `macro_rules!` items) and stay different if they came from different
1248     /// non-transparent macros.
1249     /// Technically, this operation strips all transparent marks from ident's syntactic context.
1250     pub fn normalize_to_macro_rules(self) -> Ident {
1251         Ident::new(self.name, self.span.normalize_to_macro_rules())
1252     }
1253
1254     /// Convert the name to a `SymbolStr`. This is a slowish operation because
1255     /// it requires locking the symbol interner.
1256     pub fn as_str(self) -> SymbolStr {
1257         self.name.as_str()
1258     }
1259 }
1260
1261 impl PartialEq for Ident {
1262     fn eq(&self, rhs: &Self) -> bool {
1263         self.name == rhs.name && self.span.ctxt() == rhs.span.ctxt()
1264     }
1265 }
1266
1267 impl Hash for Ident {
1268     fn hash<H: Hasher>(&self, state: &mut H) {
1269         self.name.hash(state);
1270         self.span.ctxt().hash(state);
1271     }
1272 }
1273
1274 impl fmt::Debug for Ident {
1275     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1276         fmt::Display::fmt(self, f)?;
1277         fmt::Debug::fmt(&self.span.ctxt(), f)
1278     }
1279 }
1280
1281 /// This implementation is supposed to be used in error messages, so it's expected to be identical
1282 /// to printing the original identifier token written in source code (`token_to_string`),
1283 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
1284 impl fmt::Display for Ident {
1285     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1286         fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
1287     }
1288 }
1289
1290 impl UseSpecializedEncodable for Ident {
1291     fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1292         s.emit_struct("Ident", 2, |s| {
1293             s.emit_struct_field("name", 0, |s| self.name.encode(s))?;
1294             s.emit_struct_field("span", 1, |s| self.span.encode(s))
1295         })
1296     }
1297 }
1298
1299 impl UseSpecializedDecodable for Ident {
1300     fn default_decode<D: Decoder>(d: &mut D) -> Result<Self, D::Error> {
1301         d.read_struct("Ident", 2, |d| {
1302             Ok(Ident {
1303                 name: d.read_struct_field("name", 0, Decodable::decode)?,
1304                 span: d.read_struct_field("span", 1, Decodable::decode)?,
1305             })
1306         })
1307     }
1308 }
1309
1310 /// This is the most general way to print identifiers.
1311 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
1312 /// proc macros. Additionally, proc macros may stringify their input and expect it survive the
1313 /// stringification (especially true for proc macro derives written between Rust 1.15 and 1.30).
1314 /// So we need to somehow pretty-print `$crate` in a way preserving at least some of its
1315 /// hygiene data, most importantly name of the crate it refers to.
1316 /// As a result we print `$crate` as `crate` if it refers to the local crate
1317 /// and as `::other_crate_name` if it refers to some other crate.
1318 /// Note, that this is only done if the ident token is printed from inside of AST pretty-pringing,
1319 /// but not otherwise. Pretty-printing is the only way for proc macros to discover token contents,
1320 /// so we should not perform this lossy conversion if the top level call to the pretty-printer was
1321 /// done for a token stream or a single token.
1322 pub struct IdentPrinter {
1323     symbol: Symbol,
1324     is_raw: bool,
1325     /// Span used for retrieving the crate name to which `$crate` refers to,
1326     /// if this field is `None` then the `$crate` conversion doesn't happen.
1327     convert_dollar_crate: Option<Span>,
1328 }
1329
1330 impl IdentPrinter {
1331     /// The most general `IdentPrinter` constructor. Do not use this.
1332     pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
1333         IdentPrinter { symbol, is_raw, convert_dollar_crate }
1334     }
1335
1336     /// This implementation is supposed to be used when printing identifiers
1337     /// as a part of pretty-printing for larger AST pieces.
1338     /// Do not use this either.
1339     pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
1340         IdentPrinter::new(ident.name, is_raw, Some(ident.span))
1341     }
1342 }
1343
1344 impl fmt::Display for IdentPrinter {
1345     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1346         if self.is_raw {
1347             f.write_str("r#")?;
1348         } else {
1349             if self.symbol == kw::DollarCrate {
1350                 if let Some(span) = self.convert_dollar_crate {
1351                     let converted = span.ctxt().dollar_crate_name();
1352                     if !converted.is_path_segment_keyword() {
1353                         f.write_str("::")?;
1354                     }
1355                     return fmt::Display::fmt(&converted, f);
1356                 }
1357             }
1358         }
1359         fmt::Display::fmt(&self.symbol, f)
1360     }
1361 }
1362
1363 /// An newtype around `Ident` that calls [Ident::normalize_to_macro_rules] on
1364 /// construction.
1365 // FIXME(matthewj, petrochenkov) Use this more often, add a similar
1366 // `ModernIdent` struct and use that as well.
1367 #[derive(Copy, Clone, Eq, PartialEq, Hash)]
1368 pub struct MacroRulesNormalizedIdent(Ident);
1369
1370 impl MacroRulesNormalizedIdent {
1371     pub fn new(ident: Ident) -> Self {
1372         Self(ident.normalize_to_macro_rules())
1373     }
1374 }
1375
1376 impl fmt::Debug for MacroRulesNormalizedIdent {
1377     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1378         fmt::Debug::fmt(&self.0, f)
1379     }
1380 }
1381
1382 impl fmt::Display for MacroRulesNormalizedIdent {
1383     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1384         fmt::Display::fmt(&self.0, f)
1385     }
1386 }
1387
1388 /// An interned string.
1389 ///
1390 /// Internally, a `Symbol` is implemented as an index, and all operations
1391 /// (including hashing, equality, and ordering) operate on that index. The use
1392 /// of `rustc_index::newtype_index!` means that `Option<Symbol>` only takes up 4 bytes,
1393 /// because `rustc_index::newtype_index!` reserves the last 256 values for tagging purposes.
1394 ///
1395 /// Note that `Symbol` cannot directly be a `rustc_index::newtype_index!` because it
1396 /// implements `fmt::Debug`, `Encodable`, and `Decodable` in special ways.
1397 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
1398 pub struct Symbol(SymbolIndex);
1399
1400 rustc_index::newtype_index! {
1401     pub struct SymbolIndex { .. }
1402 }
1403
1404 impl Symbol {
1405     const fn new(n: u32) -> Self {
1406         Symbol(SymbolIndex::from_u32(n))
1407     }
1408
1409     /// Maps a string to its interned representation.
1410     pub fn intern(string: &str) -> Self {
1411         with_interner(|interner| interner.intern(string))
1412     }
1413
1414     /// Access the symbol's chars. This is a slowish operation because it
1415     /// requires locking the symbol interner.
1416     pub fn with<F: FnOnce(&str) -> R, R>(self, f: F) -> R {
1417         with_interner(|interner| f(interner.get(self)))
1418     }
1419
1420     /// Convert to a `SymbolStr`. This is a slowish operation because it
1421     /// requires locking the symbol interner.
1422     pub fn as_str(self) -> SymbolStr {
1423         with_interner(|interner| unsafe {
1424             SymbolStr { string: std::mem::transmute::<&str, &str>(interner.get(self)) }
1425         })
1426     }
1427
1428     pub fn as_u32(self) -> u32 {
1429         self.0.as_u32()
1430     }
1431
1432     /// This method is supposed to be used in error messages, so it's expected to be
1433     /// identical to printing the original identifier token written in source code
1434     /// (`token_to_string`, `Ident::to_string`), except that symbols don't keep the rawness flag
1435     /// or edition, so we have to guess the rawness using the global edition.
1436     pub fn to_ident_string(self) -> String {
1437         Ident::with_dummy_span(self).to_string()
1438     }
1439 }
1440
1441 impl fmt::Debug for Symbol {
1442     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1443         self.with(|str| fmt::Debug::fmt(&str, f))
1444     }
1445 }
1446
1447 impl fmt::Display for Symbol {
1448     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1449         self.with(|str| fmt::Display::fmt(&str, f))
1450     }
1451 }
1452
1453 impl Encodable for Symbol {
1454     fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
1455         self.with(|string| s.emit_str(string))
1456     }
1457 }
1458
1459 impl Decodable for Symbol {
1460     #[inline]
1461     fn decode<D: Decoder>(d: &mut D) -> Result<Symbol, D::Error> {
1462         Ok(Symbol::intern(&d.read_str()?))
1463     }
1464 }
1465
1466 impl<CTX> HashStable<CTX> for Symbol {
1467     #[inline]
1468     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1469         self.as_str().hash_stable(hcx, hasher);
1470     }
1471 }
1472
1473 impl<CTX> ToStableHashKey<CTX> for Symbol {
1474     type KeyType = SymbolStr;
1475
1476     #[inline]
1477     fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {
1478         self.as_str()
1479     }
1480 }
1481
1482 // The `&'static str`s in this type actually point into the arena.
1483 #[derive(Default)]
1484 pub struct Interner {
1485     arena: DroplessArena,
1486     names: FxHashMap<&'static str, Symbol>,
1487     strings: Vec<&'static str>,
1488 }
1489
1490 impl Interner {
1491     fn prefill(init: &[&'static str]) -> Self {
1492         Interner {
1493             strings: init.into(),
1494             names: init.iter().copied().zip((0..).map(Symbol::new)).collect(),
1495             ..Default::default()
1496         }
1497     }
1498
1499     #[inline]
1500     pub fn intern(&mut self, string: &str) -> Symbol {
1501         if let Some(&name) = self.names.get(string) {
1502             return name;
1503         }
1504
1505         let name = Symbol::new(self.strings.len() as u32);
1506
1507         // `from_utf8_unchecked` is safe since we just allocated a `&str` which is known to be
1508         // UTF-8.
1509         let string: &str =
1510             unsafe { str::from_utf8_unchecked(self.arena.alloc_slice(string.as_bytes())) };
1511         // It is safe to extend the arena allocation to `'static` because we only access
1512         // these while the arena is still alive.
1513         let string: &'static str = unsafe { &*(string as *const str) };
1514         self.strings.push(string);
1515         self.names.insert(string, name);
1516         name
1517     }
1518
1519     // Get the symbol as a string. `Symbol::as_str()` should be used in
1520     // preference to this function.
1521     pub fn get(&self, symbol: Symbol) -> &str {
1522         self.strings[symbol.0.as_usize()]
1523     }
1524 }
1525
1526 // This module has a very short name because it's used a lot.
1527 /// This module contains all the defined keyword `Symbol`s.
1528 ///
1529 /// Given that `kw` is imported, use them like `kw::keyword_name`.
1530 /// For example `kw::Loop` or `kw::Break`.
1531 pub mod kw {
1532     use super::Symbol;
1533     keywords!();
1534 }
1535
1536 // This module has a very short name because it's used a lot.
1537 /// This module contains all the defined non-keyword `Symbol`s.
1538 ///
1539 /// Given that `sym` is imported, use them like `sym::symbol_name`.
1540 /// For example `sym::rustfmt` or `sym::u8`.
1541 #[allow(rustc::default_hash_types)]
1542 pub mod sym {
1543     use super::Symbol;
1544     use std::convert::TryInto;
1545
1546     symbols!();
1547
1548     // Used from a macro in `librustc_feature/accepted.rs`
1549     pub use super::kw::MacroRules as macro_rules;
1550
1551     // Get the symbol for an integer. The first few non-negative integers each
1552     // have a static symbol and therefore are fast.
1553     pub fn integer<N: TryInto<usize> + Copy + ToString>(n: N) -> Symbol {
1554         if let Result::Ok(idx) = n.try_into() {
1555             if let Option::Some(&sym_) = digits_array.get(idx) {
1556                 return sym_;
1557             }
1558         }
1559         Symbol::intern(&n.to_string())
1560     }
1561 }
1562
1563 impl Symbol {
1564     fn is_used_keyword_2018(self) -> bool {
1565         self >= kw::Async && self <= kw::Dyn
1566     }
1567
1568     fn is_unused_keyword_2018(self) -> bool {
1569         self == kw::Try
1570     }
1571
1572     /// Used for sanity checking rustdoc keyword sections.
1573     pub fn is_doc_keyword(self) -> bool {
1574         self <= kw::Union
1575     }
1576
1577     /// A keyword or reserved identifier that can be used as a path segment.
1578     pub fn is_path_segment_keyword(self) -> bool {
1579         self == kw::Super
1580             || self == kw::SelfLower
1581             || self == kw::SelfUpper
1582             || self == kw::Crate
1583             || self == kw::PathRoot
1584             || self == kw::DollarCrate
1585     }
1586
1587     /// Returns `true` if the symbol is `true` or `false`.
1588     pub fn is_bool_lit(self) -> bool {
1589         self == kw::True || self == kw::False
1590     }
1591
1592     /// This symbol can be a raw identifier.
1593     pub fn can_be_raw(self) -> bool {
1594         self != kw::Invalid && self != kw::Underscore && !self.is_path_segment_keyword()
1595     }
1596 }
1597
1598 impl Ident {
1599     // Returns `true` for reserved identifiers used internally for elided lifetimes,
1600     // unnamed method parameters, crate root module, error recovery etc.
1601     pub fn is_special(self) -> bool {
1602         self.name <= kw::Underscore
1603     }
1604
1605     /// Returns `true` if the token is a keyword used in the language.
1606     pub fn is_used_keyword(self) -> bool {
1607         // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1608         self.name >= kw::As && self.name <= kw::While
1609             || self.name.is_used_keyword_2018() && self.span.rust_2018()
1610     }
1611
1612     /// Returns `true` if the token is a keyword reserved for possible future use.
1613     pub fn is_unused_keyword(self) -> bool {
1614         // Note: `span.edition()` is relatively expensive, don't call it unless necessary.
1615         self.name >= kw::Abstract && self.name <= kw::Yield
1616             || self.name.is_unused_keyword_2018() && self.span.rust_2018()
1617     }
1618
1619     /// Returns `true` if the token is either a special identifier or a keyword.
1620     pub fn is_reserved(self) -> bool {
1621         self.is_special() || self.is_used_keyword() || self.is_unused_keyword()
1622     }
1623
1624     /// A keyword or reserved identifier that can be used as a path segment.
1625     pub fn is_path_segment_keyword(self) -> bool {
1626         self.name.is_path_segment_keyword()
1627     }
1628
1629     /// We see this identifier in a normal identifier position, like variable name or a type.
1630     /// How was it written originally? Did it use the raw form? Let's try to guess.
1631     pub fn is_raw_guess(self) -> bool {
1632         self.name.can_be_raw() && self.is_reserved()
1633     }
1634 }
1635
1636 #[inline]
1637 fn with_interner<T, F: FnOnce(&mut Interner) -> T>(f: F) -> T {
1638     SESSION_GLOBALS.with(|session_globals| f(&mut *session_globals.symbol_interner.lock()))
1639 }
1640
1641 /// An alternative to `Symbol`, useful when the chars within the symbol need to
1642 /// be accessed. It deliberately has limited functionality and should only be
1643 /// used for temporary values.
1644 ///
1645 /// Because the interner outlives any thread which uses this type, we can
1646 /// safely treat `string` which points to interner data, as an immortal string,
1647 /// as long as this type never crosses between threads.
1648 //
1649 // FIXME: ensure that the interner outlives any thread which uses `SymbolStr`,
1650 // by creating a new thread right after constructing the interner.
1651 #[derive(Clone, Eq, PartialOrd, Ord)]
1652 pub struct SymbolStr {
1653     string: &'static str,
1654 }
1655
1656 // This impl allows a `SymbolStr` to be directly equated with a `String` or
1657 // `&str`.
1658 impl<T: std::ops::Deref<Target = str>> std::cmp::PartialEq<T> for SymbolStr {
1659     fn eq(&self, other: &T) -> bool {
1660         self.string == other.deref()
1661     }
1662 }
1663
1664 impl !Send for SymbolStr {}
1665 impl !Sync for SymbolStr {}
1666
1667 /// This impl means that if `ss` is a `SymbolStr`:
1668 /// - `*ss` is a `str`;
1669 /// - `&*ss` is a `&str` (and `match &*ss { ... }` is a common pattern).
1670 /// - `&ss as &str` is a `&str`, which means that `&ss` can be passed to a
1671 ///   function expecting a `&str`.
1672 impl std::ops::Deref for SymbolStr {
1673     type Target = str;
1674     #[inline]
1675     fn deref(&self) -> &str {
1676         self.string
1677     }
1678 }
1679
1680 impl fmt::Debug for SymbolStr {
1681     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1682         fmt::Debug::fmt(self.string, f)
1683     }
1684 }
1685
1686 impl fmt::Display for SymbolStr {
1687     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1688         fmt::Display::fmt(self.string, f)
1689     }
1690 }
1691
1692 impl<CTX> HashStable<CTX> for SymbolStr {
1693     #[inline]
1694     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
1695         self.string.hash_stable(hcx, hasher)
1696     }
1697 }
1698
1699 impl<CTX> ToStableHashKey<CTX> for SymbolStr {
1700     type KeyType = SymbolStr;
1701
1702     #[inline]
1703     fn to_stable_hash_key(&self, _: &CTX) -> SymbolStr {
1704         self.clone()
1705     }
1706 }