syntax::feature_gate::KNOWN_ATTRIBUTES

pub const KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeGate)] = &[("warn", Normal, Ungated), ("allow", Normal, Ungated),
  ("forbid", Normal, Ungated), ("deny", Normal, Ungated),
  ("macro_reexport", Normal, Ungated), ("macro_use", Normal, Ungated),
  ("macro_export", Normal, Ungated), ("plugin_registrar", Normal, Ungated),
  ("cfg", Normal, Ungated), ("cfg_attr", Normal, Ungated),
  ("main", Normal, Ungated), ("start", Normal, Ungated),
  ("test", Normal, Ungated), ("bench", Normal, Ungated),
  ("simd", Normal, Ungated), ("repr", Normal, Ungated),
  ("path", Normal, Ungated), ("abi", Normal, Ungated),
  ("automatically_derived", Normal, Ungated), ("no_mangle", Normal, Ungated),
  ("no_link", Normal, Ungated), ("derive", Normal, Ungated),
  ("should_panic", Normal, Ungated), ("ignore", Normal, Ungated),
  ("no_implicit_prelude", Normal, Ungated),
  ("reexport_test_harness_main", Normal, Ungated),
  ("link_args", Normal, Ungated), ("macro_escape", Normal, Ungated),
  ("structural_match", Whitelisted,
   Gated("structural_match",
         "the semantics of constant patterns is not yet settled",
         { f as fn(&Features) -> bool })),
  ("no_stack_check", Normal, Ungated),
  ("plugin", CrateLevel,
   Gated("plugin", "compiler plugins are experimental and possibly buggy",
         { f as fn(&Features) -> bool })), ("no_std", CrateLevel, Ungated),
  ("no_core", CrateLevel,
   Gated("no_core", "no_core is experimental",
         { f as fn(&Features) -> bool })),
  ("lang", Normal,
   Gated("lang_items", "language items are subject to change",
         { f as fn(&Features) -> bool })),
  ("linkage", Whitelisted,
   Gated("linkage",
         "the `linkage` attribute is experimental and not portable across platforms",
         { f as fn(&Features) -> bool })),
  ("thread_local", Whitelisted,
   Gated("thread_local",
         "`#[thread_local]` is an experimental feature, and does not currently handle destructors. There is no corresponding `#[task_local]` mapping to the task model",
         { f as fn(&Features) -> bool })),
  ("rustc_on_unimplemented", Normal,
   Gated("on_unimplemented",
         "the `#[rustc_on_unimplemented]` attribute is an experimental feature",
         { f as fn(&Features) -> bool })),
  ("allocator", Whitelisted,
   Gated("allocator",
         "the `#[allocator]` attribute is an experimental feature",
         { f as fn(&Features) -> bool })),
  ("needs_allocator", Normal,
   Gated("needs_allocator",
         "the `#[needs_allocator]` attribute is an experimental feature",
         { f as fn(&Features) -> bool })),
  ("panic_runtime", Whitelisted,
   Gated("panic_runtime",
         "the `#[panic_runtime]` attribute is an experimental feature",
         { f as fn(&Features) -> bool })),
  ("needs_panic_runtime", Whitelisted,
   Gated("needs_panic_runtime",
         "the `#[needs_panic_runtime]` attribute is an experimental feature",
         { f as fn(&Features) -> bool })),
  ("rustc_variance", Normal,
   Gated("rustc_attrs",
         "the `#[rustc_variance]` attribute is just used for rustc unit tests and will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_error", Whitelisted,
   Gated("rustc_attrs",
         "the `#[rustc_error]` attribute is just used for rustc unit tests and will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_if_this_changed", Whitelisted,
   Gated("rustc_attrs",
         "the `#[rustc_if_this_changed]` attribute is just used for rustc unit tests and will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_then_this_would_need", Whitelisted,
   Gated("rustc_attrs",
         "the `#[rustc_if_this_changed]` attribute is just used for rustc unit tests and will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_dirty", Whitelisted,
   Gated("rustc_attrs",
         "the `#[rustc_dirty]` attribute is just used for rustc unit tests and will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_clean", Whitelisted,
   Gated("rustc_attrs",
         "the `#[rustc_clean]` attribute is just used for rustc unit tests and will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_symbol_name", Whitelisted,
   Gated("rustc_attrs", "internal rustc attributes will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_item_path", Whitelisted,
   Gated("rustc_attrs", "internal rustc attributes will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_move_fragments", Normal,
   Gated("rustc_attrs",
         "the `#[rustc_move_fragments]` attribute is just used for rustc unit tests and will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_mir", Whitelisted,
   Gated("rustc_attrs",
         "the `#[rustc_mir]` attribute is just used for rustc unit tests and will never be stable",
         { f as fn(&Features) -> bool })),
  ("rustc_no_mir", Whitelisted,
   Gated("rustc_attrs",
         "the `#[rustc_no_mir]` attribute is just used to make tests pass and will never be stable",
         { f as fn(&Features) -> bool })),
  ("allow_internal_unstable", Normal,
   Gated("allow_internal_unstable", EXPLAIN_ALLOW_INTERNAL_UNSTABLE,
         { f as fn(&Features) -> bool })),
  ("fundamental", Whitelisted,
   Gated("fundamental",
         "the `#[fundamental]` attribute is an experimental feature",
         { f as fn(&Features) -> bool })),
  ("linked_from", Normal,
   Gated("linked_from",
         "the `#[linked_from]` attribute is an experimental feature",
         { f as fn(&Features) -> bool })), ("doc", Whitelisted, Ungated),
  ("cold", Whitelisted, Ungated),
  ("naked", Whitelisted,
   Gated("naked_functions",
         "the `#[naked]` attribute is an experimental feature",
         { f as fn(&Features) -> bool })),
  ("export_name", Whitelisted, Ungated), ("inline", Whitelisted, Ungated),
  ("link", Whitelisted, Ungated), ("link_name", Whitelisted, Ungated),
  ("link_section", Whitelisted, Ungated),
  ("no_builtins", Whitelisted, Ungated), ("no_mangle", Whitelisted, Ungated),
  ("no_debug", Whitelisted,
   Gated("no_debug", "the `#[no_debug]` attribute is an experimental feature",
         { f as fn(&Features) -> bool })),
  ("omit_gdb_pretty_printer_section", Whitelisted,
   Gated("omit_gdb_pretty_printer_section",
         "the `#[omit_gdb_pretty_printer_section]` attribute is just used for the Rust test suite",
         { f as fn(&Features) -> bool })),
  ("unsafe_no_drop_flag", Whitelisted,
   Gated("unsafe_no_drop_flag",
         "unsafe_no_drop_flag has unstable semantics and may be removed in the future",
         { f as fn(&Features) -> bool })),
  ("unsafe_destructor_blind_to_params", Normal,
   Gated("dropck_parametricity",
         "unsafe_destructor_blind_to_params has unstable semantics and may be removed in the future",
         { f as fn(&Features) -> bool })),
  ("unwind", Whitelisted,
   Gated("unwind_attributes", "#[unwind] is experimental",
         { f as fn(&Features) -> bool })),
  ("prelude_import", Whitelisted,
   Gated("prelude_import", "`#[prelude_import]` is for use by rustc only",
         { f as fn(&Features) -> bool })),
  ("rustc_deprecated", Whitelisted, Ungated),
  ("must_use", Whitelisted, Ungated), ("stable", Whitelisted, Ungated),
  ("unstable", Whitelisted, Ungated), ("deprecated", Normal, Ungated),
  ("rustc_paren_sugar", Normal,
   Gated("unboxed_closures", "unboxed_closures are still evolving",
         { f as fn(&Features) -> bool })),
  ("rustc_reflect_like", Whitelisted,
   Gated("reflect", "defining reflective traits is still evolving",
         { f as fn(&Features) -> bool })),
  ("crate_name", CrateLevel, Ungated), ("crate_type", CrateLevel, Ungated),
  ("crate_id", CrateLevel, Ungated), ("feature", CrateLevel, Ungated),
  ("no_start", CrateLevel, Ungated), ("no_main", CrateLevel, Ungated),
  ("no_builtins", CrateLevel, Ungated),
  ("recursion_limit", CrateLevel, Ungated)]

Unstable (rustc_private)