compiler/rustc_feature/src/removed.rs

   1 //! List of the removed feature gates.
   2
   3 use super::{to_nonzero, Feature, State};
   4 use rustc_span::symbol::sym;
   5
   6 macro_rules! declare_features {
   7     ($(
   8         $(#[doc = $doc:tt])* (removed, $feature:ident, $ver:expr, $issue:expr, None, $reason:expr),
   9     )+) => {
  10         /// Represents unstable features which have since been removed (it was once Active)
  11         pub const REMOVED_FEATURES: &[Feature] = &[
  12             $(
  13                 Feature {
  14                     state: State::Removed { reason: $reason },
  15                     name: sym::$feature,
  16                     since: $ver,
  17                     issue: to_nonzero($issue),
  18                     edition: None,
  19                 }
  20             ),+
  21         ];
  22     };
  23
  24     ($(
  25         $(#[doc = $doc:tt])* (stable_removed, $feature:ident, $ver:expr, $issue:expr, None),
  26     )+) => {
  27         /// Represents stable features which have since been removed (it was once Accepted)
  28         pub const STABLE_REMOVED_FEATURES: &[Feature] = &[
  29             $(
  30                 Feature {
  31                     state: State::Stabilized { reason: None },
  32                     name: sym::$feature,
  33                     since: $ver,
  34                     issue: to_nonzero($issue),
  35                     edition: None,
  36                 }
  37             ),+
  38         ];
  39     };
  40 }
  41
  42 #[rustfmt::skip]
  43 declare_features! (
  44     // -------------------------------------------------------------------------
  45     // feature-group-start: removed features
  46     // -------------------------------------------------------------------------
  47
  48     (removed, advanced_slice_patterns, "1.0.0", Some(62254), None,
  49      Some("merged into `#![feature(slice_patterns)]`")),
  50     (removed, allocator, "1.0.0", None, None, None),
  51     /// Allows a test to fail without failing the whole suite.
  52     (removed, allow_fail, "1.19.0", Some(46488), None, Some("removed due to no clear use cases")),
  53     (removed, await_macro, "1.38.0", Some(50547), None,
  54      Some("subsumed by `.await` syntax")),
  55     /// Allows using the `box $expr` syntax.
  56     (removed, box_syntax, "1.70.0", Some(49733), None, Some("replaced with `#[rustc_box]`")),
  57     /// Allows capturing disjoint fields in a closure/generator (RFC 2229).
  58     (removed, capture_disjoint_fields, "1.49.0", Some(53488), None, Some("stabilized in Rust 2021")),
  59     /// Allows comparing raw pointers during const eval.
  60     (removed, const_compare_raw_pointers, "1.46.0", Some(53020), None,
  61      Some("cannot be allowed in const eval in any meaningful way")),
  62     /// Allows non-trivial generic constants which have to be manually propagated upwards.
  63      (removed, const_evaluatable_checked, "1.48.0", Some(76560), None, Some("renamed to `generic_const_exprs`")),
  64     /// Allows the definition of `const` functions with some advanced features.
  65     (removed, const_fn, "1.54.0", Some(57563), None,
  66      Some("split into finer-grained feature gates")),
  67     /// Allows const generic types (e.g. `struct Foo<const N: usize>(...);`).
  68     (removed, const_generics, "1.34.0", Some(44580), None,
  69      Some("removed in favor of `#![feature(adt_const_params)]` and `#![feature(generic_const_exprs)]`")),
  70     /// Allows `[x; N]` where `x` is a constant (RFC 2203).
  71     (removed, const_in_array_repeat_expressions,  "1.37.0", Some(49147), None,
  72      Some("removed due to causing promotable bugs")),
  73     /// Allows casting raw pointers to `usize` during const eval.
  74     (removed, const_raw_ptr_to_usize_cast, "1.55.0", Some(51910), None,
  75      Some("at compile-time, pointers do not have an integer value, so these casts cannot be properly supported")),
  76     /// Allows `T: ?const Trait` syntax in bounds.
  77     (removed, const_trait_bound_opt_out, "1.42.0", Some(67794), None,
  78      Some("Removed in favor of `~const` bound in #![feature(const_trait_impl)]")),
  79     /// Allows using `crate` as visibility modifier, synonymous with `pub(crate)`.
  80     (removed, crate_visibility_modifier, "1.63.0", Some(53120), None, Some("removed in favor of `pub(crate)`")),
  81     /// Allows using custom attributes (RFC 572).
  82     (removed, custom_attribute, "1.0.0", Some(29642), None,
  83      Some("removed in favor of `#![register_tool]` and `#![register_attr]`")),
  84     /// Allows the use of `#[derive(Anything)]` as sugar for `#[derive_Anything]`.
  85     (removed, custom_derive, "1.32.0", Some(29644), None,
  86      Some("subsumed by `#[proc_macro_derive]`")),
  87     /// Allows using `#[doc(keyword = "...")]`.
  88     (removed, doc_keyword, "1.28.0", Some(51315), None,
  89      Some("merged into `#![feature(rustdoc_internals)]`")),
  90     /// Allows using `doc(primitive)` without a future-incompat warning.
  91     (removed, doc_primitive, "1.56.0", Some(88070), None,
  92      Some("merged into `#![feature(rustdoc_internals)]`")),
  93     /// Allows `#[doc(spotlight)]`.
  94     /// The attribute was renamed to `#[doc(notable_trait)]`
  95     /// and the feature to `doc_notable_trait`.
  96     (removed, doc_spotlight, "1.22.0", Some(45040), None,
  97      Some("renamed to `doc_notable_trait`")),
  98     /// Allows using `#[unsafe_destructor_blind_to_params]` (RFC 1238).
  99     (removed, dropck_parametricity, "1.38.0", Some(28498), None, None),
 100     /// Allows defining `existential type`s.
 101     (removed, existential_type, "1.38.0", Some(63063), None,
 102      Some("removed in favor of `#![feature(type_alias_impl_trait)]`")),
 103     /// Paths of the form: `extern::foo::bar`
 104     (removed, extern_in_paths, "1.33.0", Some(55600), None,
 105      Some("subsumed by `::foo::bar` paths")),
 106     /// Allows `#[doc(include = "some-file")]`.
 107     (removed, external_doc, "1.54.0", Some(44732), None,
 108      Some("use #[doc = include_str!(\"filename\")] instead, which handles macro invocations")),
 109     /// Allows `impl Trait` in bindings (`let`, `const`, `static`).
 110     (removed, impl_trait_in_bindings, "1.55.0", Some(63065), None,
 111      Some("the implementation was not maintainable, the feature may get reintroduced once the current refactorings are done")),
 112     (removed, import_shadowing, "1.0.0", None, None, None),
 113     /// Allows in-band quantification of lifetime bindings (e.g., `fn foo(x: &'a u8) -> &'a u8`).
 114     (removed, in_band_lifetimes, "1.23.0", Some(44524), None,
 115      Some("removed due to unsolved ergonomic questions and added lifetime resolution complexity")),
 116     /// Allows inferring `'static` outlives requirements (RFC 2093).
 117     (removed, infer_static_outlives_requirements, "1.63.0", Some(54185), None,
 118      Some("removed as it caused some confusion and discussion was inactive for years")),
 119     /// Lazily evaluate constants. This allows constants to depend on type parameters.
 120     (removed, lazy_normalization_consts, "1.46.0", Some(72219), None, Some("superseded by `generic_const_exprs`")),
 121     /// Allows using the `#[link_args]` attribute.
 122     (removed, link_args, "1.53.0", Some(29596), None,
 123      Some("removed in favor of using `-C link-arg=ARG` on command line, \
 124            which is available from cargo build scripts with `cargo:rustc-link-arg` now")),
 125     (removed, macro_reexport, "1.0.0", Some(29638), None,
 126      Some("subsumed by `pub use`")),
 127     /// Allows using `#[main]` to replace the entrypoint `#[lang = "start"]` calls.
 128     (removed, main, "1.53.0", Some(29634), None, None),
 129     (removed, managed_boxes, "1.0.0", None, None, None),
 130     /// Allows the use of type alias impl trait in function return positions
 131     (removed, min_type_alias_impl_trait, "1.56.0", Some(63063), None,
 132      Some("removed in favor of full type_alias_impl_trait")),
 133     (removed, needs_allocator, "1.4.0", Some(27389), None,
 134      Some("subsumed by `#![feature(allocator_internals)]`")),
 135     /// Allows use of unary negate on unsigned integers, e.g., -e for e: u8
 136     (removed, negate_unsigned, "1.0.0", Some(29645), None, None),
 137     /// Allows `#[no_debug]`.
 138     (removed, no_debug, "1.43.0", Some(29721), None, Some("removed due to lack of demand")),
 139     /// Allows using `#[on_unimplemented(..)]` on traits.
 140     /// (Moved to `rustc_attrs`.)
 141     (removed, on_unimplemented, "1.40.0", None, None, None),
 142     /// A way to temporarily opt out of opt-in copy. This will *never* be accepted.
 143     (removed, opt_out_copy, "1.0.0", None, None, None),
 144     /// Allows features specific to OIBIT (now called auto traits).
 145     /// Renamed to `auto_traits`.
 146     (removed, optin_builtin_traits, "1.0.0", Some(13231), None,
 147      Some("renamed to `auto_traits`")),
 148     /// Allows overlapping impls of marker traits.
 149     (removed, overlapping_marker_traits, "1.42.0", Some(29864), None,
 150      Some("removed in favor of `#![feature(marker_trait_attr)]`")),
 151     (removed, panic_implementation, "1.28.0", Some(44489), None,
 152      Some("subsumed by `#[panic_handler]`")),
 153     /// Allows using `#[plugin_registrar]` on functions.
 154     (removed, plugin_registrar, "1.54.0", Some(29597), None,
 155      Some("a __rustc_plugin_registrar symbol must now be defined instead")),
 156     (removed, proc_macro_expr, "1.27.0", Some(54727), None,
 157      Some("subsumed by `#![feature(proc_macro_hygiene)]`")),
 158     (removed, proc_macro_gen, "1.27.0", Some(54727), None,
 159      Some("subsumed by `#![feature(proc_macro_hygiene)]`")),
 160     (removed, proc_macro_mod, "1.27.0", Some(54727), None,
 161      Some("subsumed by `#![feature(proc_macro_hygiene)]`")),
 162     (removed, proc_macro_non_items, "1.27.0", Some(54727), None,
 163      Some("subsumed by `#![feature(proc_macro_hygiene)]`")),
 164     (removed, pub_macro_rules, "1.53.0", Some(78855), None,
 165      Some("removed due to being incomplete, in particular it does not work across crates")),
 166     (removed, pushpop_unsafe, "1.2.0", None, None, None),
 167     (removed, quad_precision_float, "1.0.0", None, None, None),
 168     (removed, quote, "1.33.0", Some(29601), None, None),
 169     (removed, reflect, "1.0.0", Some(27749), None, None),
 170     /// Allows using the `#[register_attr]` attribute.
 171     (removed, register_attr, "1.65.0", Some(66080), None,
 172      Some("removed in favor of `#![register_tool]`")),
 173     /// Allows using the macros:
 174     /// + `__diagnostic_used`
 175     /// + `__register_diagnostic`
 176     /// +`__build_diagnostic_array`
 177     (removed, rustc_diagnostic_macros, "1.38.0", None, None, None),
 178     /// Allows identifying crates that contain sanitizer runtimes.
 179     (removed, sanitizer_runtime, "1.17.0", None, None, None),
 180     (removed, simd, "1.0.0", Some(27731), None,
 181      Some("removed in favor of `#[repr(simd)]`")),
 182     /// Allows `#[link(kind = "static-nobundle", ...)]`.
 183     (removed, static_nobundle, "1.16.0", Some(37403), None,
 184      Some(r#"subsumed by `#[link(kind = "static", modifiers = "-bundle", ...)]`"#)),
 185     (removed, struct_inherit, "1.0.0", None, None, None),
 186     (removed, test_removed_feature, "1.0.0", None, None, None),
 187     /// Allows using items which are missing stability attributes
 188     (removed, unmarked_api, "1.0.0", None, None, None),
 189     (removed, unsafe_no_drop_flag, "1.0.0", None, None, None),
 190     /// Allows `union` fields that don't implement `Copy` as long as they don't have any drop glue.
 191     (removed, untagged_unions, "1.13.0", Some(55149), None,
 192      Some("unions with `Copy` and `ManuallyDrop` fields are stable; there is no intent to stabilize more")),
 193     /// Allows `#[unwind(..)]`.
 194     ///
 195     /// Permits specifying whether a function should permit unwinding or abort on unwind.
 196     (removed, unwind_attributes, "1.56.0", Some(58760), None, Some("use the C-unwind ABI instead")),
 197     (removed, visible_private_types, "1.0.0", None, None, None),
 198     // !!!!    !!!!    !!!!    !!!!   !!!!    !!!!    !!!!    !!!!    !!!!    !!!!    !!!!
 199     // Features are listed in alphabetical order. Tidy will fail if you don't keep it this way.
 200     // !!!!    !!!!    !!!!    !!!!   !!!!    !!!!    !!!!    !!!!    !!!!    !!!!    !!!!
 201
 202     // -------------------------------------------------------------------------
 203     // feature-group-end: removed features
 204     // -------------------------------------------------------------------------
 205 );
 206
 207 #[rustfmt::skip]
 208 declare_features! (
 209     (stable_removed, no_stack_check, "1.0.0", None, None),
 210 );