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Diffstat (limited to 'compiler/rustc_feature/src/builtin_attrs.rs')
| -rw-r--r-- | compiler/rustc_feature/src/builtin_attrs.rs | 602 |
1 files changed, 602 insertions, 0 deletions
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs new file mode 100644 index 00000000000..879f06f89a7 --- /dev/null +++ b/compiler/rustc_feature/src/builtin_attrs.rs @@ -0,0 +1,602 @@ +//! Built-in attributes and `cfg` flag gating. + +use AttributeGate::*; +use AttributeType::*; + +use crate::{Features, Stability}; + +use lazy_static::lazy_static; +use rustc_data_structures::fx::FxHashMap; +use rustc_span::symbol::{sym, Symbol}; + +type GateFn = fn(&Features) -> bool; + +macro_rules! cfg_fn { + ($field: ident) => { + (|features| features.$field) as GateFn + }; +} + +pub type GatedCfg = (Symbol, Symbol, GateFn); + +/// `cfg(...)`'s that are feature gated. +const GATED_CFGS: &[GatedCfg] = &[ + // (name in cfg, feature, function to check if the feature is enabled) + (sym::target_thread_local, sym::cfg_target_thread_local, cfg_fn!(cfg_target_thread_local)), + (sym::target_has_atomic, sym::cfg_target_has_atomic, cfg_fn!(cfg_target_has_atomic)), + (sym::target_has_atomic_load_store, sym::cfg_target_has_atomic, cfg_fn!(cfg_target_has_atomic)), + (sym::sanitize, sym::cfg_sanitize, cfg_fn!(cfg_sanitize)), + (sym::version, sym::cfg_version, cfg_fn!(cfg_version)), +]; + +/// Find a gated cfg determined by the `pred`icate which is given the cfg's name. +pub fn find_gated_cfg(pred: impl Fn(Symbol) -> bool) -> Option<&'static GatedCfg> { + GATED_CFGS.iter().find(|(cfg_sym, ..)| pred(*cfg_sym)) +} + +// If you change this, please modify `src/doc/unstable-book` as well. You must +// move that documentation into the relevant place in the other docs, and +// remove the chapter on the flag. + +#[derive(Copy, Clone, PartialEq, Debug)] +pub enum AttributeType { + /// Normal, builtin attribute that is consumed + /// by the compiler before the unused_attribute check + Normal, + + /// Builtin attribute that may not be consumed by the compiler + /// before the unused_attribute check. These attributes + /// will be ignored by the unused_attribute lint + AssumedUsed, + + /// Builtin attribute that is only allowed at the crate level + CrateLevel, +} + +#[derive(Clone, Copy)] +pub enum AttributeGate { + /// Is gated by a given feature gate, reason + /// and function to check if enabled + Gated(Stability, Symbol, &'static str, fn(&Features) -> bool), + + /// Ungated attribute, can be used on all release channels + Ungated, +} + +// fn() is not Debug +impl std::fmt::Debug for AttributeGate { + fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + match *self { + Self::Gated(ref stab, name, expl, _) => { + write!(fmt, "Gated({:?}, {}, {})", stab, name, expl) + } + Self::Ungated => write!(fmt, "Ungated"), + } + } +} + +impl AttributeGate { + fn is_deprecated(&self) -> bool { + match *self { + Self::Gated(Stability::Deprecated(_, _), ..) => true, + _ => false, + } + } +} + +/// A template that the attribute input must match. +/// Only top-level shape (`#[attr]` vs `#[attr(...)]` vs `#[attr = ...]`) is considered now. +#[derive(Clone, Copy, Default)] +pub struct AttributeTemplate { + pub word: bool, + pub list: Option<&'static str>, + pub name_value_str: Option<&'static str>, +} + +/// A convenience macro for constructing attribute templates. +/// E.g., `template!(Word, List: "description")` means that the attribute +/// supports forms `#[attr]` and `#[attr(description)]`. +macro_rules! template { + (Word) => { template!(@ true, None, None) }; + (List: $descr: expr) => { template!(@ false, Some($descr), None) }; + (NameValueStr: $descr: expr) => { template!(@ false, None, Some($descr)) }; + (Word, List: $descr: expr) => { template!(@ true, Some($descr), None) }; + (Word, NameValueStr: $descr: expr) => { template!(@ true, None, Some($descr)) }; + (List: $descr1: expr, NameValueStr: $descr2: expr) => { + template!(@ false, Some($descr1), Some($descr2)) + }; + (Word, List: $descr1: expr, NameValueStr: $descr2: expr) => { + template!(@ true, Some($descr1), Some($descr2)) + }; + (@ $word: expr, $list: expr, $name_value_str: expr) => { AttributeTemplate { + word: $word, list: $list, name_value_str: $name_value_str + } }; +} + +macro_rules! ungated { + ($attr:ident, $typ:expr, $tpl:expr $(,)?) => { + (sym::$attr, $typ, $tpl, Ungated) + }; +} + +macro_rules! gated { + ($attr:ident, $typ:expr, $tpl:expr, $gate:ident, $msg:expr $(,)?) => { + (sym::$attr, $typ, $tpl, Gated(Stability::Unstable, sym::$gate, $msg, cfg_fn!($gate))) + }; + ($attr:ident, $typ:expr, $tpl:expr, $msg:expr $(,)?) => { + (sym::$attr, $typ, $tpl, Gated(Stability::Unstable, sym::$attr, $msg, cfg_fn!($attr))) + }; +} + +macro_rules! rustc_attr { + (TEST, $attr:ident, $typ:expr, $tpl:expr $(,)?) => { + rustc_attr!( + $attr, + $typ, + $tpl, + concat!( + "the `#[", + stringify!($attr), + "]` attribute is just used for rustc unit tests \ + and will never be stable", + ), + ) + }; + ($attr:ident, $typ:expr, $tpl:expr, $msg:expr $(,)?) => { + ( + sym::$attr, + $typ, + $tpl, + Gated(Stability::Unstable, sym::rustc_attrs, $msg, cfg_fn!(rustc_attrs)), + ) + }; +} + +macro_rules! experimental { + ($attr:ident) => { + concat!("the `#[", stringify!($attr), "]` attribute is an experimental feature") + }; +} + +const IMPL_DETAIL: &str = "internal implementation detail"; +const INTERNAL_UNSTABLE: &str = "this is an internal attribute that will never be stable"; + +pub type BuiltinAttribute = (Symbol, AttributeType, AttributeTemplate, AttributeGate); + +/// Attributes that have a special meaning to rustc or rustdoc. +#[rustfmt::skip] +pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[ + // ========================================================================== + // Stable attributes: + // ========================================================================== + + // Conditional compilation: + ungated!(cfg, Normal, template!(List: "predicate")), + ungated!(cfg_attr, Normal, template!(List: "predicate, attr1, attr2, ...")), + + // Testing: + ungated!(ignore, Normal, template!(Word, NameValueStr: "reason")), + ungated!( + should_panic, Normal, + template!(Word, List: r#"expected = "reason"#, NameValueStr: "reason"), + ), + // FIXME(Centril): This can be used on stable but shouldn't. + ungated!(reexport_test_harness_main, Normal, template!(NameValueStr: "name")), + + // Macros: + ungated!(derive, Normal, template!(List: "Trait1, Trait2, ...")), + ungated!(automatically_derived, Normal, template!(Word)), + // FIXME(#14407) + ungated!(macro_use, Normal, template!(Word, List: "name1, name2, ...")), + ungated!(macro_escape, Normal, template!(Word)), // Deprecated synonym for `macro_use`. + ungated!(macro_export, Normal, template!(Word, List: "local_inner_macros")), + ungated!(proc_macro, Normal, template!(Word)), + ungated!( + proc_macro_derive, Normal, + template!(List: "TraitName, /*opt*/ attributes(name1, name2, ...)"), + ), + ungated!(proc_macro_attribute, Normal, template!(Word)), + + // Lints: + ungated!(warn, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)), + ungated!(allow, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)), + ungated!(forbid, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)), + ungated!(deny, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)), + ungated!(must_use, AssumedUsed, template!(Word, NameValueStr: "reason")), + // FIXME(#14407) + ungated!( + deprecated, Normal, + template!( + Word, + List: r#"/*opt*/ since = "version", /*opt*/ note = "reason""#, + NameValueStr: "reason" + ), + ), + + // Crate properties: + ungated!(crate_name, CrateLevel, template!(NameValueStr: "name")), + ungated!(crate_type, CrateLevel, template!(NameValueStr: "bin|lib|...")), + ungated!(crate_id, CrateLevel, template!(NameValueStr: "ignored")), + + // ABI, linking, symbols, and FFI + ungated!( + link, AssumedUsed, + template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...""#), + ), + ungated!(link_name, AssumedUsed, template!(NameValueStr: "name")), + ungated!(no_link, Normal, template!(Word)), + ungated!(repr, Normal, template!(List: "C")), + ungated!(export_name, AssumedUsed, template!(NameValueStr: "name")), + ungated!(link_section, AssumedUsed, template!(NameValueStr: "name")), + ungated!(no_mangle, AssumedUsed, template!(Word)), + ungated!(used, AssumedUsed, template!(Word)), + + // Limits: + ungated!(recursion_limit, CrateLevel, template!(NameValueStr: "N")), + ungated!(type_length_limit, CrateLevel, template!(NameValueStr: "N")), + gated!( + const_eval_limit, CrateLevel, template!(NameValueStr: "N"), const_eval_limit, + experimental!(const_eval_limit) + ), + + // Entry point: + ungated!(main, Normal, template!(Word)), + ungated!(start, Normal, template!(Word)), + ungated!(no_start, CrateLevel, template!(Word)), + ungated!(no_main, CrateLevel, template!(Word)), + + // Modules, prelude, and resolution: + ungated!(path, Normal, template!(NameValueStr: "file")), + ungated!(no_std, CrateLevel, template!(Word)), + ungated!(no_implicit_prelude, Normal, template!(Word)), + ungated!(non_exhaustive, AssumedUsed, template!(Word)), + + // Runtime + ungated!(windows_subsystem, AssumedUsed, template!(NameValueStr: "windows|console")), + ungated!(panic_handler, Normal, template!(Word)), // RFC 2070 + + // Code generation: + ungated!(inline, AssumedUsed, template!(Word, List: "always|never")), + ungated!(cold, AssumedUsed, template!(Word)), + ungated!(no_builtins, AssumedUsed, template!(Word)), + ungated!(target_feature, AssumedUsed, template!(List: r#"enable = "name""#)), + ungated!(track_caller, AssumedUsed, template!(Word)), + gated!( + no_sanitize, AssumedUsed, + template!(List: "address, memory, thread"), + experimental!(no_sanitize) + ), + + // FIXME: #14408 assume docs are used since rustdoc looks at them. + ungated!(doc, AssumedUsed, template!(List: "hidden|inline|...", NameValueStr: "string")), + + // ========================================================================== + // Unstable attributes: + // ========================================================================== + + // Linking: + gated!(naked, AssumedUsed, template!(Word), naked_functions, experimental!(naked)), + gated!( + link_args, Normal, template!(NameValueStr: "args"), + "the `link_args` attribute is experimental and not portable across platforms, \ + it is recommended to use `#[link(name = \"foo\")] instead", + ), + gated!( + link_ordinal, AssumedUsed, template!(List: "ordinal"), raw_dylib, + experimental!(link_ordinal) + ), + + // Plugins: + ( + sym::plugin_registrar, Normal, template!(Word), + Gated( + Stability::Deprecated( + "https://github.com/rust-lang/rust/pull/64675", + Some("may be removed in a future compiler version"), + ), + sym::plugin_registrar, + "compiler plugins are deprecated", + cfg_fn!(plugin_registrar) + ) + ), + ( + sym::plugin, CrateLevel, template!(List: "name"), + Gated( + Stability::Deprecated( + "https://github.com/rust-lang/rust/pull/64675", + Some("may be removed in a future compiler version"), + ), + sym::plugin, + "compiler plugins are deprecated", + cfg_fn!(plugin) + ) + ), + + // Testing: + gated!(allow_fail, Normal, template!(Word), experimental!(allow_fail)), + gated!( + test_runner, CrateLevel, template!(List: "path"), custom_test_frameworks, + "custom test frameworks are an unstable feature", + ), + // RFC #1268 + gated!(marker, Normal, template!(Word), marker_trait_attr, experimental!(marker)), + gated!( + thread_local, AssumedUsed, template!(Word), + "`#[thread_local]` is an experimental feature, and does not currently handle destructors", + ), + gated!(no_core, CrateLevel, template!(Word), experimental!(no_core)), + // RFC 2412 + gated!( + optimize, AssumedUsed, template!(List: "size|speed"), optimize_attribute, + experimental!(optimize), + ), + + gated!(ffi_returns_twice, AssumedUsed, template!(Word), experimental!(ffi_returns_twice)), + gated!(ffi_pure, AssumedUsed, template!(Word), experimental!(ffi_pure)), + gated!(ffi_const, AssumedUsed, template!(Word), experimental!(ffi_const)), + gated!( + register_attr, CrateLevel, template!(List: "attr1, attr2, ..."), + experimental!(register_attr), + ), + gated!( + register_tool, CrateLevel, template!(List: "tool1, tool2, ..."), + experimental!(register_tool), + ), + + // ========================================================================== + // Internal attributes: Stability, deprecation, and unsafe: + // ========================================================================== + + ungated!(feature, CrateLevel, template!(List: "name1, name1, ...")), + // FIXME(#14407) -- only looked at on-demand so we can't + // guarantee they'll have already been checked. + ungated!( + rustc_deprecated, AssumedUsed, + template!(List: r#"since = "version", reason = "...""#) + ), + // FIXME(#14407) + ungated!(stable, AssumedUsed, template!(List: r#"feature = "name", since = "version""#)), + // FIXME(#14407) + ungated!( + unstable, AssumedUsed, + template!(List: r#"feature = "name", reason = "...", issue = "N""#), + ), + // FIXME(#14407) + ungated!(rustc_const_unstable, AssumedUsed, template!(List: r#"feature = "name""#)), + // FIXME(#14407) + ungated!(rustc_const_stable, AssumedUsed, template!(List: r#"feature = "name""#)), + gated!( + allow_internal_unstable, AssumedUsed, template!(Word, List: "feat1, feat2, ..."), + "allow_internal_unstable side-steps feature gating and stability checks", + ), + gated!( + allow_internal_unsafe, Normal, template!(Word), + "allow_internal_unsafe side-steps the unsafe_code lint", + ), + + // ========================================================================== + // Internal attributes: Type system related: + // ========================================================================== + + gated!(fundamental, AssumedUsed, template!(Word), experimental!(fundamental)), + gated!( + may_dangle, Normal, template!(Word), dropck_eyepatch, + "`may_dangle` has unstable semantics and may be removed in the future", + ), + + // ========================================================================== + // Internal attributes: Runtime related: + // ========================================================================== + + rustc_attr!(rustc_allocator, AssumedUsed, template!(Word), IMPL_DETAIL), + rustc_attr!(rustc_allocator_nounwind, AssumedUsed, template!(Word), IMPL_DETAIL), + gated!(alloc_error_handler, Normal, template!(Word), experimental!(alloc_error_handler)), + gated!( + default_lib_allocator, AssumedUsed, template!(Word), allocator_internals, + experimental!(default_lib_allocator), + ), + gated!( + needs_allocator, Normal, template!(Word), allocator_internals, + experimental!(needs_allocator), + ), + gated!(panic_runtime, AssumedUsed, template!(Word), experimental!(panic_runtime)), + gated!(needs_panic_runtime, AssumedUsed, template!(Word), experimental!(needs_panic_runtime)), + gated!( + unwind, AssumedUsed, template!(List: "allowed|aborts"), unwind_attributes, + experimental!(unwind), + ), + gated!( + compiler_builtins, AssumedUsed, template!(Word), + "the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate \ + which contains compiler-rt intrinsics and will never be stable", + ), + gated!( + profiler_runtime, AssumedUsed, template!(Word), + "the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate \ + which contains the profiler runtime and will never be stable", + ), + + // ========================================================================== + // Internal attributes, Linkage: + // ========================================================================== + + gated!( + linkage, AssumedUsed, template!(NameValueStr: "external|internal|..."), + "the `linkage` attribute is experimental and not portable across platforms", + ), + rustc_attr!(rustc_std_internal_symbol, AssumedUsed, template!(Word), INTERNAL_UNSTABLE), + + // ========================================================================== + // Internal attributes, Macro related: + // ========================================================================== + + rustc_attr!(rustc_builtin_macro, AssumedUsed, template!(Word), IMPL_DETAIL), + rustc_attr!(rustc_proc_macro_decls, Normal, template!(Word), INTERNAL_UNSTABLE), + rustc_attr!( + rustc_macro_transparency, AssumedUsed, + template!(NameValueStr: "transparent|semitransparent|opaque"), + "used internally for testing macro hygiene", + ), + + // ========================================================================== + // Internal attributes, Diagnostics related: + // ========================================================================== + + rustc_attr!( + rustc_on_unimplemented, AssumedUsed, + template!( + List: r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#, + NameValueStr: "message" + ), + INTERNAL_UNSTABLE + ), + // Enumerates "identity-like" conversion methods to suggest on type mismatch. + rustc_attr!(rustc_conversion_suggestion, AssumedUsed, template!(Word), INTERNAL_UNSTABLE), + + // ========================================================================== + // Internal attributes, Const related: + // ========================================================================== + + rustc_attr!(rustc_promotable, AssumedUsed, template!(Word), IMPL_DETAIL), + rustc_attr!(rustc_allow_const_fn_ptr, AssumedUsed, template!(Word), IMPL_DETAIL), + rustc_attr!(rustc_args_required_const, AssumedUsed, template!(List: "N"), INTERNAL_UNSTABLE), + + // ========================================================================== + // Internal attributes, Layout related: + // ========================================================================== + + rustc_attr!( + rustc_layout_scalar_valid_range_start, AssumedUsed, template!(List: "value"), + "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \ + niche optimizations in libcore and will never be stable", + ), + rustc_attr!( + rustc_layout_scalar_valid_range_end, AssumedUsed, template!(List: "value"), + "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \ + niche optimizations in libcore and will never be stable", + ), + rustc_attr!( + rustc_nonnull_optimization_guaranteed, AssumedUsed, template!(Word), + "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable \ + niche optimizations in libcore and will never be stable", + ), + + // ========================================================================== + // Internal attributes, Misc: + // ========================================================================== + gated!( + lang, Normal, template!(NameValueStr: "name"), lang_items, + "language items are subject to change", + ), + ( + sym::rustc_diagnostic_item, + Normal, + template!(NameValueStr: "name"), + Gated( + Stability::Unstable, + sym::rustc_attrs, + "diagnostic items compiler internal support for linting", + cfg_fn!(rustc_attrs), + ), + ), + gated!( + // Used in resolve: + prelude_import, AssumedUsed, template!(Word), + "`#[prelude_import]` is for use by rustc only", + ), + gated!( + rustc_paren_sugar, Normal, template!(Word), unboxed_closures, + "unboxed_closures are still evolving", + ), + rustc_attr!( + rustc_inherit_overflow_checks, AssumedUsed, template!(Word), + "the `#[rustc_inherit_overflow_checks]` attribute is just used to control \ + overflow checking behavior of several libcore functions that are inlined \ + across crates and will never be stable", + ), + rustc_attr!(rustc_reservation_impl, Normal, template!(NameValueStr: "reservation message"), + "the `#[rustc_reservation_impl]` attribute is internally used \ + for reserving for `for<T> From<!> for T` impl" + ), + rustc_attr!( + rustc_test_marker, Normal, template!(Word), + "the `#[rustc_test_marker]` attribute is used internally to track tests", + ), + rustc_attr!( + rustc_unsafe_specialization_marker, Normal, template!(Word), + "the `#[rustc_unsafe_specialization_marker]` attribute is used to check specializations" + ), + rustc_attr!( + rustc_specialization_trait, Normal, template!(Word), + "the `#[rustc_specialization_trait]` attribute is used to check specializations" + ), + + // ========================================================================== + // Internal attributes, Testing: + // ========================================================================== + + rustc_attr!(TEST, rustc_outlives, Normal, template!(Word)), + rustc_attr!(TEST, rustc_variance, Normal, template!(Word)), + rustc_attr!(TEST, rustc_layout, Normal, template!(List: "field1, field2, ...")), + rustc_attr!(TEST, rustc_regions, Normal, template!(Word)), + rustc_attr!( + TEST, rustc_error, AssumedUsed, + template!(Word, List: "delay_span_bug_from_inside_query") + ), + rustc_attr!(TEST, rustc_dump_user_substs, AssumedUsed, template!(Word)), + rustc_attr!(TEST, rustc_if_this_changed, AssumedUsed, template!(Word, List: "DepNode")), + rustc_attr!(TEST, rustc_then_this_would_need, AssumedUsed, template!(List: "DepNode")), + rustc_attr!( + TEST, rustc_dirty, AssumedUsed, + template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#), + ), + rustc_attr!( + TEST, rustc_clean, AssumedUsed, + template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#), + ), + rustc_attr!( + TEST, rustc_partition_reused, AssumedUsed, + template!(List: r#"cfg = "...", module = "...""#), + ), + rustc_attr!( + TEST, rustc_partition_codegened, AssumedUsed, + template!(List: r#"cfg = "...", module = "...""#), + ), + rustc_attr!( + TEST, rustc_expected_cgu_reuse, AssumedUsed, + template!(List: r#"cfg = "...", module = "...", kind = "...""#), + ), + rustc_attr!(TEST, rustc_synthetic, AssumedUsed, template!(Word)), + rustc_attr!(TEST, rustc_symbol_name, AssumedUsed, template!(Word)), + rustc_attr!(TEST, rustc_polymorphize_error, AssumedUsed, template!(Word)), + rustc_attr!(TEST, rustc_def_path, AssumedUsed, template!(Word)), + rustc_attr!(TEST, rustc_mir, AssumedUsed, template!(List: "arg1, arg2, ...")), + rustc_attr!(TEST, rustc_dump_program_clauses, AssumedUsed, template!(Word)), + rustc_attr!(TEST, rustc_dump_env_program_clauses, AssumedUsed, template!(Word)), + rustc_attr!(TEST, rustc_object_lifetime_default, AssumedUsed, template!(Word)), + rustc_attr!(TEST, rustc_dummy, Normal, template!(Word /* doesn't matter*/)), + gated!( + omit_gdb_pretty_printer_section, AssumedUsed, template!(Word), + "the `#[omit_gdb_pretty_printer_section]` attribute is just used for the Rust test suite", + ), +]; + +pub fn deprecated_attributes() -> Vec<&'static BuiltinAttribute> { + BUILTIN_ATTRIBUTES.iter().filter(|(.., gate)| gate.is_deprecated()).collect() +} + +pub fn is_builtin_attr_name(name: Symbol) -> bool { + BUILTIN_ATTRIBUTE_MAP.get(&name).is_some() +} + +lazy_static! { + pub static ref BUILTIN_ATTRIBUTE_MAP: FxHashMap<Symbol, &'static BuiltinAttribute> = { + let mut map = FxHashMap::default(); + for attr in BUILTIN_ATTRIBUTES.iter() { + if map.insert(attr.0, attr).is_some() { + panic!("duplicate builtin attribute `{}`", attr.0); + } + } + map + }; +} |