| //! # Feature gating |
| //! |
| //! This module implements the gating necessary for preventing certain compiler |
| //! features from being used by default. This module will crawl a pre-expanded |
| //! AST to ensure that there are no features which are used that are not |
| //! enabled. |
| //! |
| //! Features are enabled in programs via the crate-level attributes of |
| //! `#![feature(...)]` with a comma-separated list of features. |
| //! |
| //! For the purpose of future feature-tracking, once code for detection of feature |
| //! gate usage is added, *do not remove it again* even once the feature |
| //! becomes stable. |
| |
| use AttributeType::*; |
| use AttributeGate::*; |
| |
| use crate::ast::{ |
| self, AssocTyConstraint, AssocTyConstraintKind, NodeId, GenericParam, GenericParamKind, |
| PatKind, RangeEnd, |
| }; |
| use crate::attr::{self, check_builtin_attribute, AttributeTemplate}; |
| use crate::source_map::Spanned; |
| use crate::edition::{ALL_EDITIONS, Edition}; |
| use crate::visit::{self, FnKind, Visitor}; |
| use crate::parse::{token, ParseSess}; |
| use crate::parse::parser::Parser; |
| use crate::symbol::{Symbol, sym}; |
| use crate::tokenstream::TokenTree; |
| |
| use errors::{Applicability, DiagnosticBuilder, Handler}; |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_target::spec::abi::Abi; |
| use syntax_pos::{Span, DUMMY_SP, MultiSpan}; |
| use log::debug; |
| use lazy_static::lazy_static; |
| |
| use std::env; |
| |
| macro_rules! set { |
| ($field: ident) => {{ |
| fn f(features: &mut Features, _: Span) { |
| features.$field = true; |
| } |
| f as fn(&mut Features, Span) |
| }} |
| } |
| |
| macro_rules! declare_features { |
| ($((active, $feature: ident, $ver: expr, $issue: expr, $edition: expr),)+) => { |
| /// Represents active features that are currently being implemented or |
| /// currently being considered for addition/removal. |
| const ACTIVE_FEATURES: |
| &[(Symbol, &str, Option<u32>, Option<Edition>, fn(&mut Features, Span))] = |
| &[$((sym::$feature, $ver, $issue, $edition, set!($feature))),+]; |
| |
| /// A set of features to be used by later passes. |
| #[derive(Clone)] |
| pub struct Features { |
| /// `#![feature]` attrs for language features, for error reporting |
| pub declared_lang_features: Vec<(Symbol, Span, Option<Symbol>)>, |
| /// `#![feature]` attrs for non-language (library) features |
| pub declared_lib_features: Vec<(Symbol, Span)>, |
| $(pub $feature: bool),+ |
| } |
| |
| impl Features { |
| pub fn new() -> Features { |
| Features { |
| declared_lang_features: Vec::new(), |
| declared_lib_features: Vec::new(), |
| $($feature: false),+ |
| } |
| } |
| |
| pub fn walk_feature_fields<F>(&self, mut f: F) |
| where F: FnMut(&str, bool) |
| { |
| $(f(stringify!($feature), self.$feature);)+ |
| } |
| } |
| }; |
| |
| ($((removed, $feature: ident, $ver: expr, $issue: expr, None, $reason: expr),)+) => { |
| /// Represents unstable features which have since been removed (it was once Active) |
| const REMOVED_FEATURES: &[(Symbol, &str, Option<u32>, Option<&str>)] = &[ |
| $((sym::$feature, $ver, $issue, $reason)),+ |
| ]; |
| }; |
| |
| ($((stable_removed, $feature: ident, $ver: expr, $issue: expr, None),)+) => { |
| /// Represents stable features which have since been removed (it was once Accepted) |
| const STABLE_REMOVED_FEATURES: &[(Symbol, &str, Option<u32>, Option<&str>)] = &[ |
| $((sym::$feature, $ver, $issue, None)),+ |
| ]; |
| }; |
| |
| ($((accepted, $feature: ident, $ver: expr, $issue: expr, None),)+) => { |
| /// Those language feature has since been Accepted (it was once Active) |
| const ACCEPTED_FEATURES: &[(Symbol, &str, Option<u32>, Option<&str>)] = &[ |
| $((sym::$feature, $ver, $issue, None)),+ |
| ]; |
| } |
| } |
| |
| // If you change this, please modify `src/doc/unstable-book` as well. |
| // |
| // Don't ever remove anything from this list; set them to 'Removed'. |
| // |
| // The version numbers here correspond to the version in which the current status |
| // was set. This is most important for knowing when a particular feature became |
| // stable (active). |
| // |
| // Note that the features are grouped into internal/user-facing and then |
| // sorted by version inside those groups. This is inforced with tidy. |
| // |
| // N.B., `tools/tidy/src/features.rs` parses this information directly out of the |
| // source, so take care when modifying it. |
| |
| declare_features! ( |
| // ------------------------------------------------------------------------- |
| // feature-group-start: internal feature gates |
| // ------------------------------------------------------------------------- |
| |
| // no-tracking-issue-start |
| |
| // Allows using compiler's own crates. |
| (active, rustc_private, "1.0.0", Some(27812), None), |
| |
| // Allows using the `rust-intrinsic`'s "ABI". |
| (active, intrinsics, "1.0.0", None, None), |
| |
| // Allows using `#[lang = ".."]` attribute for linking items to special compiler logic. |
| (active, lang_items, "1.0.0", None, None), |
| |
| // Allows using the `#[stable]` and `#[unstable]` attributes. |
| (active, staged_api, "1.0.0", None, None), |
| |
| // Allows using `#[allow_internal_unstable]`. This is an |
| // attribute on `macro_rules!` and can't use the attribute handling |
| // below (it has to be checked before expansion possibly makes |
| // macros disappear). |
| (active, allow_internal_unstable, "1.0.0", None, None), |
| |
| // Allows using `#[allow_internal_unsafe]`. This is an |
| // attribute on `macro_rules!` and can't use the attribute handling |
| // below (it has to be checked before expansion possibly makes |
| // macros disappear). |
| (active, allow_internal_unsafe, "1.0.0", None, None), |
| |
| // Allows using the macros: |
| // + `__diagnostic_used` |
| // + `__register_diagnostic` |
| // +`__build_diagnostic_array` |
| (active, rustc_diagnostic_macros, "1.0.0", None, None), |
| |
| // Allows using `#[rustc_const_unstable(feature = "foo", ..)]` which |
| // lets a function to be `const` when opted into with `#![feature(foo)]`. |
| (active, rustc_const_unstable, "1.0.0", None, None), |
| |
| // no-tracking-issue-end |
| |
| // Allows using `#[link_name="llvm.*"]`. |
| (active, link_llvm_intrinsics, "1.0.0", Some(29602), None), |
| |
| // Allows using `rustc_*` attributes (RFC 572). |
| (active, rustc_attrs, "1.0.0", Some(29642), None), |
| |
| // Allows using `#[on_unimplemented(..)]` on traits. |
| (active, on_unimplemented, "1.0.0", Some(29628), None), |
| |
| // Allows using the `box $expr` syntax. |
| (active, box_syntax, "1.0.0", Some(49733), None), |
| |
| // Allows using `#[main]` to replace the entrypoint `#[lang = "start"]` calls. |
| (active, main, "1.0.0", Some(29634), None), |
| |
| // Allows using `#[start]` on a function indicating that it is the program entrypoint. |
| (active, start, "1.0.0", Some(29633), None), |
| |
| // Allows using the `#[fundamental]` attribute. |
| (active, fundamental, "1.0.0", Some(29635), None), |
| |
| // Allows using the `rust-call` ABI. |
| (active, unboxed_closures, "1.0.0", Some(29625), None), |
| |
| // Allows using the `#[linkage = ".."]` attribute. |
| (active, linkage, "1.0.0", Some(29603), None), |
| |
| // Allows features specific to OIBIT (auto traits). |
| (active, optin_builtin_traits, "1.0.0", Some(13231), None), |
| |
| // Allows using `box` in patterns (RFC 469). |
| (active, box_patterns, "1.0.0", Some(29641), None), |
| |
| // no-tracking-issue-start |
| |
| // Allows using `#[prelude_import]` on glob `use` items. |
| (active, prelude_import, "1.2.0", None, None), |
| |
| // no-tracking-issue-end |
| |
| // no-tracking-issue-start |
| |
| // Allows using `#[omit_gdb_pretty_printer_section]`. |
| (active, omit_gdb_pretty_printer_section, "1.5.0", None, None), |
| |
| // Allows using the `vectorcall` ABI. |
| (active, abi_vectorcall, "1.7.0", None, None), |
| |
| // no-tracking-issue-end |
| |
| // Allows using `#[structural_match]` which indicates that a type is structurally matchable. |
| (active, structural_match, "1.8.0", Some(31434), None), |
| |
| // Allows using the `may_dangle` attribute (RFC 1327). |
| (active, dropck_eyepatch, "1.10.0", Some(34761), None), |
| |
| // Allows using the `#![panic_runtime]` attribute. |
| (active, panic_runtime, "1.10.0", Some(32837), None), |
| |
| // Allows declaring with `#![needs_panic_runtime]` that a panic runtime is needed. |
| (active, needs_panic_runtime, "1.10.0", Some(32837), None), |
| |
| // no-tracking-issue-start |
| |
| // Allows identifying the `compiler_builtins` crate. |
| (active, compiler_builtins, "1.13.0", None, None), |
| |
| // Allows using the `unadjusted` ABI; perma-unstable. |
| (active, abi_unadjusted, "1.16.0", None, None), |
| |
| // Allows identifying crates that contain sanitizer runtimes. |
| (active, sanitizer_runtime, "1.17.0", None, None), |
| |
| // Used to identify crates that contain the profiler runtime. |
| (active, profiler_runtime, "1.18.0", None, None), |
| |
| // Allows using the `thiscall` ABI. |
| (active, abi_thiscall, "1.19.0", None, None), |
| |
| // Allows using `#![needs_allocator]`, an implementation detail of `#[global_allocator]`. |
| (active, allocator_internals, "1.20.0", None, None), |
| |
| // no-tracking-issue-end |
| |
| // Added for testing E0705; perma-unstable. |
| (active, test_2018_feature, "1.31.0", Some(0), Some(Edition::Edition2018)), |
| |
| // ------------------------------------------------------------------------- |
| // feature-group-end: internal feature gates |
| // ------------------------------------------------------------------------- |
| |
| // ------------------------------------------------------------------------- |
| // feature-group-start: actual feature gates (target features) |
| // ------------------------------------------------------------------------- |
| |
| // FIXME: Document these and merge with the list below. |
| |
| // Unstable `#[target_feature]` directives. |
| (active, arm_target_feature, "1.27.0", Some(44839), None), |
| (active, aarch64_target_feature, "1.27.0", Some(44839), None), |
| (active, hexagon_target_feature, "1.27.0", Some(44839), None), |
| (active, powerpc_target_feature, "1.27.0", Some(44839), None), |
| (active, mips_target_feature, "1.27.0", Some(44839), None), |
| (active, avx512_target_feature, "1.27.0", Some(44839), None), |
| (active, mmx_target_feature, "1.27.0", Some(44839), None), |
| (active, sse4a_target_feature, "1.27.0", Some(44839), None), |
| (active, tbm_target_feature, "1.27.0", Some(44839), None), |
| (active, wasm_target_feature, "1.30.0", Some(44839), None), |
| (active, adx_target_feature, "1.32.0", Some(44839), None), |
| (active, cmpxchg16b_target_feature, "1.32.0", Some(44839), None), |
| (active, movbe_target_feature, "1.34.0", Some(44839), None), |
| (active, rtm_target_feature, "1.35.0", Some(44839), None), |
| (active, f16c_target_feature, "1.36.0", Some(44839), None), |
| |
| // ------------------------------------------------------------------------- |
| // feature-group-end: actual feature gates (target features) |
| // ------------------------------------------------------------------------- |
| |
| // ------------------------------------------------------------------------- |
| // feature-group-start: actual feature gates |
| // ------------------------------------------------------------------------- |
| |
| // Allows using the `#[link_args]` attribute. |
| (active, link_args, "1.0.0", Some(29596), None), |
| |
| // Allows defining identifiers beyond ASCII. |
| (active, non_ascii_idents, "1.0.0", Some(55467), None), |
| |
| // Allows using `#[plugin_registrar]` on functions. |
| (active, plugin_registrar, "1.0.0", Some(29597), None), |
| |
| // Allows using `#![plugin(myplugin)]`. |
| (active, plugin, "1.0.0", Some(29597), None), |
| |
| // Allows using `#[thread_local]` on `static` items. |
| (active, thread_local, "1.0.0", Some(29594), None), |
| |
| // Allows the use of SIMD types in functions declared in `extern` blocks. |
| (active, simd_ffi, "1.0.0", Some(27731), None), |
| |
| // Allows using custom attributes (RFC 572). |
| (active, custom_attribute, "1.0.0", Some(29642), None), |
| |
| // Allows using non lexical lifetimes (RFC 2094). |
| (active, nll, "1.0.0", Some(43234), None), |
| |
| // Allows using slice patterns. |
| (active, slice_patterns, "1.0.0", Some(62254), None), |
| |
| // Allows the definition of `const` functions with some advanced features. |
| (active, const_fn, "1.2.0", Some(57563), None), |
| |
| // Allows associated type defaults. |
| (active, associated_type_defaults, "1.2.0", Some(29661), None), |
| |
| // Allows `#![no_core]`. |
| (active, no_core, "1.3.0", Some(29639), None), |
| |
| // Allows default type parameters to influence type inference. |
| (active, default_type_parameter_fallback, "1.3.0", Some(27336), None), |
| |
| // Allows `repr(simd)` and importing the various simd intrinsics. |
| (active, repr_simd, "1.4.0", Some(27731), None), |
| |
| // Allows `extern "platform-intrinsic" { ... }`. |
| (active, platform_intrinsics, "1.4.0", Some(27731), None), |
| |
| // Allows `#[unwind(..)]`. |
| // |
| // Permits specifying whether a function should permit unwinding or abort on unwind. |
| (active, unwind_attributes, "1.4.0", Some(58760), None), |
| |
| // Allows `#[no_debug]`. |
| (active, no_debug, "1.5.0", Some(29721), None), |
| |
| // Allows attributes on expressions and non-item statements. |
| (active, stmt_expr_attributes, "1.6.0", Some(15701), None), |
| |
| // Allows the use of type ascription in expressions. |
| (active, type_ascription, "1.6.0", Some(23416), None), |
| |
| // Allows `cfg(target_thread_local)`. |
| (active, cfg_target_thread_local, "1.7.0", Some(29594), None), |
| |
| // Allows specialization of implementations (RFC 1210). |
| (active, specialization, "1.7.0", Some(31844), None), |
| |
| // Allows using `#[naked]` on functions. |
| (active, naked_functions, "1.9.0", Some(32408), None), |
| |
| // Allows `cfg(target_has_atomic = "...")`. |
| (active, cfg_target_has_atomic, "1.9.0", Some(32976), None), |
| |
| // Allows `X..Y` patterns. |
| (active, exclusive_range_pattern, "1.11.0", Some(37854), None), |
| |
| // Allows the `!` type. Does not imply 'exhaustive_patterns' (below) any more. |
| (active, never_type, "1.13.0", Some(35121), None), |
| |
| // Allows exhaustive pattern matching on types that contain uninhabited types. |
| (active, exhaustive_patterns, "1.13.0", Some(51085), None), |
| |
| // Allows untagged unions `union U { ... }`. |
| (active, untagged_unions, "1.13.0", Some(32836), None), |
| |
| // Allows `#[link(..., cfg(..))]`. |
| (active, link_cfg, "1.14.0", Some(37406), None), |
| |
| // Allows `extern "ptx-*" fn()`. |
| (active, abi_ptx, "1.15.0", Some(38788), None), |
| |
| // Allows the `#[repr(i128)]` attribute for enums. |
| (active, repr128, "1.16.0", Some(35118), None), |
| |
| // Allows `#[link(kind="static-nobundle"...)]`. |
| (active, static_nobundle, "1.16.0", Some(37403), None), |
| |
| // Allows `extern "msp430-interrupt" fn()`. |
| (active, abi_msp430_interrupt, "1.16.0", Some(38487), None), |
| |
| // Allows declarative macros 2.0 (`macro`). |
| (active, decl_macro, "1.17.0", Some(39412), None), |
| |
| // Allows `extern "x86-interrupt" fn()`. |
| (active, abi_x86_interrupt, "1.17.0", Some(40180), None), |
| |
| // Allows overlapping impls of marker traits. |
| (active, overlapping_marker_traits, "1.18.0", Some(29864), None), |
| |
| // Allows a test to fail without failing the whole suite. |
| (active, allow_fail, "1.19.0", Some(46488), None), |
| |
| // Allows unsized tuple coercion. |
| (active, unsized_tuple_coercion, "1.20.0", Some(42877), None), |
| |
| // Allows defining generators. |
| (active, generators, "1.21.0", Some(43122), None), |
| |
| // Allows `#[doc(cfg(...))]`. |
| (active, doc_cfg, "1.21.0", Some(43781), None), |
| |
| // Allows `#[doc(masked)]`. |
| (active, doc_masked, "1.21.0", Some(44027), None), |
| |
| // Allows `#[doc(spotlight)]`. |
| (active, doc_spotlight, "1.22.0", Some(45040), None), |
| |
| // Allows `#[doc(include = "some-file")]`. |
| (active, external_doc, "1.22.0", Some(44732), None), |
| |
| // Allows future-proofing enums/structs with the `#[non_exhaustive]` attribute (RFC 2008). |
| (active, non_exhaustive, "1.22.0", Some(44109), None), |
| |
| // Allows using `crate` as visibility modifier, synonymous with `pub(crate)`. |
| (active, crate_visibility_modifier, "1.23.0", Some(53120), None), |
| |
| // Allows defining `extern type`s. |
| (active, extern_types, "1.23.0", Some(43467), None), |
| |
| // Allows trait methods with arbitrary self types. |
| (active, arbitrary_self_types, "1.23.0", Some(44874), None), |
| |
| // Allows in-band quantification of lifetime bindings (e.g., `fn foo(x: &'a u8) -> &'a u8`). |
| (active, in_band_lifetimes, "1.23.0", Some(44524), None), |
| |
| // Allows associated types to be generic, e.g., `type Foo<T>;` (RFC 1598). |
| (active, generic_associated_types, "1.23.0", Some(44265), None), |
| |
| // Allows defining `trait X = A + B;` alias items. |
| (active, trait_alias, "1.24.0", Some(41517), None), |
| |
| // Allows infering `'static` outlives requirements (RFC 2093). |
| (active, infer_static_outlives_requirements, "1.26.0", Some(54185), None), |
| |
| // Allows macro invocations in `extern {}` blocks. |
| (active, macros_in_extern, "1.27.0", Some(49476), None), |
| |
| // Allows accessing fields of unions inside `const` functions. |
| (active, const_fn_union, "1.27.0", Some(51909), None), |
| |
| // Allows casting raw pointers to `usize` during const eval. |
| (active, const_raw_ptr_to_usize_cast, "1.27.0", Some(51910), None), |
| |
| // Allows dereferencing raw pointers during const eval. |
| (active, const_raw_ptr_deref, "1.27.0", Some(51911), None), |
| |
| // Allows comparing raw pointers during const eval. |
| (active, const_compare_raw_pointers, "1.27.0", Some(53020), None), |
| |
| // Allows `#[doc(alias = "...")]`. |
| (active, doc_alias, "1.27.0", Some(50146), None), |
| |
| // Allows inconsistent bounds in where clauses. |
| (active, trivial_bounds, "1.28.0", Some(48214), None), |
| |
| // Allows `'a: { break 'a; }`. |
| (active, label_break_value, "1.28.0", Some(48594), None), |
| |
| // Allows using `#[doc(keyword = "...")]`. |
| (active, doc_keyword, "1.28.0", Some(51315), None), |
| |
| // Allows async and await syntax. |
| (active, async_await, "1.28.0", Some(50547), None), |
| |
| // Allows reinterpretation of the bits of a value of one type as another type during const eval. |
| (active, const_transmute, "1.29.0", Some(53605), None), |
| |
| // Allows using `try {...}` expressions. |
| (active, try_blocks, "1.29.0", Some(31436), None), |
| |
| // Allows defining an `#[alloc_error_handler]`. |
| (active, alloc_error_handler, "1.29.0", Some(51540), None), |
| |
| // Allows using the `amdgpu-kernel` ABI. |
| (active, abi_amdgpu_kernel, "1.29.0", Some(51575), None), |
| |
| // Allows panicking during const eval (producing compile-time errors). |
| (active, const_panic, "1.30.0", Some(51999), None), |
| |
| // Allows `#[marker]` on certain traits allowing overlapping implementations. |
| (active, marker_trait_attr, "1.30.0", Some(29864), None), |
| |
| // Allows macro invocations on modules expressions and statements and |
| // procedural macros to expand to non-items. |
| (active, proc_macro_hygiene, "1.30.0", Some(54727), None), |
| |
| // Allows unsized rvalues at arguments and parameters. |
| (active, unsized_locals, "1.30.0", Some(48055), None), |
| |
| // Allows custom test frameworks with `#![test_runner]` and `#[test_case]`. |
| (active, custom_test_frameworks, "1.30.0", Some(50297), None), |
| |
| // Allows non-builtin attributes in inner attribute position. |
| (active, custom_inner_attributes, "1.30.0", Some(54726), None), |
| |
| // Allows mixing bind-by-move in patterns and references to those identifiers in guards. |
| (active, bind_by_move_pattern_guards, "1.30.0", Some(15287), None), |
| |
| // Allows `impl Trait` in bindings (`let`, `const`, `static`). |
| (active, impl_trait_in_bindings, "1.30.0", Some(63065), None), |
| |
| // Allows using `reason` in lint attributes and the `#[expect(lint)]` lint check. |
| (active, lint_reasons, "1.31.0", Some(54503), None), |
| |
| // Allows exhaustive integer pattern matching on `usize` and `isize`. |
| (active, precise_pointer_size_matching, "1.32.0", Some(56354), None), |
| |
| // Allows relaxing the coherence rules such that |
| // `impl<T> ForeignTrait<LocalType> for ForeignType<T> is permitted. |
| (active, re_rebalance_coherence, "1.32.0", Some(55437), None), |
| |
| // Allows using `#[ffi_returns_twice]` on foreign functions. |
| (active, ffi_returns_twice, "1.34.0", Some(58314), None), |
| |
| // Allows const generic types (e.g. `struct Foo<const N: usize>(...);`). |
| (active, const_generics, "1.34.0", Some(44580), None), |
| |
| // Allows using `#[optimize(X)]`. |
| (active, optimize_attribute, "1.34.0", Some(54882), None), |
| |
| // Allows using C-variadics. |
| (active, c_variadic, "1.34.0", Some(44930), None), |
| |
| // Allows the user of associated type bounds. |
| (active, associated_type_bounds, "1.34.0", Some(52662), None), |
| |
| // Attributes on formal function params. |
| (active, param_attrs, "1.36.0", Some(60406), None), |
| |
| // Allows calling constructor functions in `const fn`. |
| (active, const_constructor, "1.37.0", Some(61456), None), |
| |
| // Allows `if/while p && let q = r && ...` chains. |
| (active, let_chains, "1.37.0", Some(53667), None), |
| |
| // Allows #[repr(transparent)] on enums (RFC 2645). |
| (active, transparent_enums, "1.37.0", Some(60405), None), |
| |
| // Allows #[repr(transparent)] on unions (RFC 2645). |
| (active, transparent_unions, "1.37.0", Some(60405), None), |
| |
| // Allows explicit discriminants on non-unit enum variants. |
| (active, arbitrary_enum_discriminant, "1.37.0", Some(60553), None), |
| |
| // Allows `impl Trait` with multiple unrelated lifetimes. |
| (active, member_constraints, "1.37.0", Some(61977), None), |
| |
| // Allows `async || body` closures. |
| (active, async_closure, "1.37.0", Some(62290), None), |
| |
| // Allows the use of `#[cfg(doctest)]`, set when rustdoc is collecting doctests |
| (active, cfg_doctest, "1.37.0", Some(62210), None), |
| |
| // Allows `[x; N]` where `x` is a constant (RFC 2203). |
| (active, const_in_array_repeat_expressions, "1.37.0", Some(49147), None), |
| |
| // Allows `impl Trait` to be used inside type aliases (RFC 2515). |
| (active, type_alias_impl_trait, "1.38.0", Some(63063), None), |
| |
| // ------------------------------------------------------------------------- |
| // feature-group-end: actual feature gates |
| // ------------------------------------------------------------------------- |
| ); |
| |
| /// Some features are known to be incomplete and using them is likely to have |
| /// unanticipated results, such as compiler crashes. We warn the user about these |
| /// to alert them. |
| pub const INCOMPLETE_FEATURES: &[Symbol] = &[ |
| sym::impl_trait_in_bindings, |
| sym::generic_associated_types, |
| sym::const_generics, |
| sym::let_chains, |
| ]; |
| |
| declare_features! ( |
| // ------------------------------------------------------------------------- |
| // feature-group-start: removed features |
| // ------------------------------------------------------------------------- |
| |
| (removed, import_shadowing, "1.0.0", None, None, None), |
| (removed, managed_boxes, "1.0.0", None, None, None), |
| // Allows use of unary negate on unsigned integers, e.g., -e for e: u8 |
| (removed, negate_unsigned, "1.0.0", Some(29645), None, None), |
| (removed, reflect, "1.0.0", Some(27749), None, None), |
| // A way to temporarily opt out of opt in copy. This will *never* be accepted. |
| (removed, opt_out_copy, "1.0.0", None, None, None), |
| (removed, quad_precision_float, "1.0.0", None, None, None), |
| (removed, struct_inherit, "1.0.0", None, None, None), |
| (removed, test_removed_feature, "1.0.0", None, None, None), |
| (removed, visible_private_types, "1.0.0", None, None, None), |
| (removed, unsafe_no_drop_flag, "1.0.0", None, None, None), |
| // Allows using items which are missing stability attributes |
| (removed, unmarked_api, "1.0.0", None, None, None), |
| (removed, allocator, "1.0.0", None, None, None), |
| (removed, simd, "1.0.0", Some(27731), None, |
| Some("removed in favor of `#[repr(simd)]`")), |
| (removed, advanced_slice_patterns, "1.0.0", Some(62254), None, |
| Some("merged into `#![feature(slice_patterns)]`")), |
| (removed, macro_reexport, "1.0.0", Some(29638), None, |
| Some("subsumed by `pub use`")), |
| (removed, pushpop_unsafe, "1.2.0", None, None, None), |
| (removed, needs_allocator, "1.4.0", Some(27389), None, |
| Some("subsumed by `#![feature(allocator_internals)]`")), |
| (removed, proc_macro_mod, "1.27.0", Some(54727), None, |
| Some("subsumed by `#![feature(proc_macro_hygiene)]`")), |
| (removed, proc_macro_expr, "1.27.0", Some(54727), None, |
| Some("subsumed by `#![feature(proc_macro_hygiene)]`")), |
| (removed, proc_macro_non_items, "1.27.0", Some(54727), None, |
| Some("subsumed by `#![feature(proc_macro_hygiene)]`")), |
| (removed, proc_macro_gen, "1.27.0", Some(54727), None, |
| Some("subsumed by `#![feature(proc_macro_hygiene)]`")), |
| (removed, panic_implementation, "1.28.0", Some(44489), None, |
| Some("subsumed by `#[panic_handler]`")), |
| // Allows the use of `#[derive(Anything)]` as sugar for `#[derive_Anything]`. |
| (removed, custom_derive, "1.32.0", Some(29644), None, |
| Some("subsumed by `#[proc_macro_derive]`")), |
| // Paths of the form: `extern::foo::bar` |
| (removed, extern_in_paths, "1.33.0", Some(55600), None, |
| Some("subsumed by `::foo::bar` paths")), |
| (removed, quote, "1.33.0", Some(29601), None, None), |
| // Allows using `#[unsafe_destructor_blind_to_params]` (RFC 1238). |
| (removed, dropck_parametricity, "1.38.0", Some(28498), None, None), |
| (removed, await_macro, "1.38.0", Some(50547), None, |
| Some("subsumed by `.await` syntax")), |
| // Allows defining `existential type`s. |
| (removed, existential_type, "1.38.0", Some(63063), None, |
| Some("removed in favor of `#![feature(type_alias_impl_trait)]`")), |
| |
| // ------------------------------------------------------------------------- |
| // feature-group-end: removed features |
| // ------------------------------------------------------------------------- |
| ); |
| |
| declare_features! ( |
| (stable_removed, no_stack_check, "1.0.0", None, None), |
| ); |
| |
| declare_features! ( |
| // ------------------------------------------------------------------------- |
| // feature-group-start: for testing purposes |
| // ------------------------------------------------------------------------- |
| |
| // A temporary feature gate used to enable parser extensions needed |
| // to bootstrap fix for #5723. |
| (accepted, issue_5723_bootstrap, "1.0.0", None, None), |
| // These are used to test this portion of the compiler, |
| // they don't actually mean anything. |
| (accepted, test_accepted_feature, "1.0.0", None, None), |
| |
| // ------------------------------------------------------------------------- |
| // feature-group-end: for testing purposes |
| // ------------------------------------------------------------------------- |
| |
| // ------------------------------------------------------------------------- |
| // feature-group-start: accepted features |
| // ------------------------------------------------------------------------- |
| |
| // Allows using associated `type`s in `trait`s. |
| (accepted, associated_types, "1.0.0", None, None), |
| // Allows using assigning a default type to type parameters in algebraic data type definitions. |
| (accepted, default_type_params, "1.0.0", None, None), |
| // FIXME: explain `globs`. |
| (accepted, globs, "1.0.0", None, None), |
| // Allows `macro_rules!` items. |
| (accepted, macro_rules, "1.0.0", None, None), |
| // Allows use of `&foo[a..b]` as a slicing syntax. |
| (accepted, slicing_syntax, "1.0.0", None, None), |
| // Allows struct variants `Foo { baz: u8, .. }` in enums (RFC 418). |
| (accepted, struct_variant, "1.0.0", None, None), |
| // Allows indexing tuples. |
| (accepted, tuple_indexing, "1.0.0", None, None), |
| // Allows the use of `if let` expressions. |
| (accepted, if_let, "1.0.0", None, None), |
| // Allows the use of `while let` expressions. |
| (accepted, while_let, "1.0.0", None, None), |
| // Allows using `#![no_std]`. |
| (accepted, no_std, "1.6.0", None, None), |
| // Allows overloading augmented assignment operations like `a += b`. |
| (accepted, augmented_assignments, "1.8.0", Some(28235), None), |
| // Allows empty structs and enum variants with braces. |
| (accepted, braced_empty_structs, "1.8.0", Some(29720), None), |
| // Allows `#[deprecated]` attribute. |
| (accepted, deprecated, "1.9.0", Some(29935), None), |
| // Allows macros to appear in the type position. |
| (accepted, type_macros, "1.13.0", Some(27245), None), |
| // Allows use of the postfix `?` operator in expressions. |
| (accepted, question_mark, "1.13.0", Some(31436), None), |
| // Allows `..` in tuple (struct) patterns. |
| (accepted, dotdot_in_tuple_patterns, "1.14.0", Some(33627), None), |
| // Allows some increased flexibility in the name resolution rules, |
| // especially around globs and shadowing (RFC 1560). |
| (accepted, item_like_imports, "1.15.0", Some(35120), None), |
| // Allows using `Self` and associated types in struct expressions and patterns. |
| (accepted, more_struct_aliases, "1.16.0", Some(37544), None), |
| // Allows elision of `'static` lifetimes in `static`s and `const`s. |
| (accepted, static_in_const, "1.17.0", Some(35897), None), |
| // Allows field shorthands (`x` meaning `x: x`) in struct literal expressions. |
| (accepted, field_init_shorthand, "1.17.0", Some(37340), None), |
| // Allows the definition recursive static items. |
| (accepted, static_recursion, "1.17.0", Some(29719), None), |
| // Allows `pub(restricted)` visibilities (RFC 1422). |
| (accepted, pub_restricted, "1.18.0", Some(32409), None), |
| // Allows `#![windows_subsystem]`. |
| (accepted, windows_subsystem, "1.18.0", Some(37499), None), |
| // Allows `break {expr}` with a value inside `loop`s. |
| (accepted, loop_break_value, "1.19.0", Some(37339), None), |
| // Allows numeric fields in struct expressions and patterns. |
| (accepted, relaxed_adts, "1.19.0", Some(35626), None), |
| // Allows coercing non capturing closures to function pointers. |
| (accepted, closure_to_fn_coercion, "1.19.0", Some(39817), None), |
| // Allows attributes on struct literal fields. |
| (accepted, struct_field_attributes, "1.20.0", Some(38814), None), |
| // Allows the definition of associated constants in `trait` or `impl` blocks. |
| (accepted, associated_consts, "1.20.0", Some(29646), None), |
| // Allows usage of the `compile_error!` macro. |
| (accepted, compile_error, "1.20.0", Some(40872), None), |
| // Allows code like `let x: &'static u32 = &42` to work (RFC 1414). |
| (accepted, rvalue_static_promotion, "1.21.0", Some(38865), None), |
| // Allows `Drop` types in constants (RFC 1440). |
| (accepted, drop_types_in_const, "1.22.0", Some(33156), None), |
| // Allows the sysV64 ABI to be specified on all platforms |
| // instead of just the platforms on which it is the C ABI. |
| (accepted, abi_sysv64, "1.24.0", Some(36167), None), |
| // Allows `repr(align(16))` struct attribute (RFC 1358). |
| (accepted, repr_align, "1.25.0", Some(33626), None), |
| // Allows '|' at beginning of match arms (RFC 1925). |
| (accepted, match_beginning_vert, "1.25.0", Some(44101), None), |
| // Allows nested groups in `use` items (RFC 2128). |
| (accepted, use_nested_groups, "1.25.0", Some(44494), None), |
| // Allows indexing into constant arrays. |
| (accepted, const_indexing, "1.26.0", Some(29947), None), |
| // Allows using `a..=b` and `..=b` as inclusive range syntaxes. |
| (accepted, inclusive_range_syntax, "1.26.0", Some(28237), None), |
| // Allows `..=` in patterns (RFC 1192). |
| (accepted, dotdoteq_in_patterns, "1.26.0", Some(28237), None), |
| // Allows `fn main()` with return types which implements `Termination` (RFC 1937). |
| (accepted, termination_trait, "1.26.0", Some(43301), None), |
| // Allows implementing `Clone` for closures where possible (RFC 2132). |
| (accepted, clone_closures, "1.26.0", Some(44490), None), |
| // Allows implementing `Copy` for closures where possible (RFC 2132). |
| (accepted, copy_closures, "1.26.0", Some(44490), None), |
| // Allows `impl Trait` in function arguments. |
| (accepted, universal_impl_trait, "1.26.0", Some(34511), None), |
| // Allows `impl Trait` in function return types. |
| (accepted, conservative_impl_trait, "1.26.0", Some(34511), None), |
| // Allows using the `u128` and `i128` types. |
| (accepted, i128_type, "1.26.0", Some(35118), None), |
| // Allows default match binding modes (RFC 2005). |
| (accepted, match_default_bindings, "1.26.0", Some(42640), None), |
| // Allows `'_` placeholder lifetimes. |
| (accepted, underscore_lifetimes, "1.26.0", Some(44524), None), |
| // Allows attributes on lifetime/type formal parameters in generics (RFC 1327). |
| (accepted, generic_param_attrs, "1.27.0", Some(48848), None), |
| // Allows `cfg(target_feature = "...")`. |
| (accepted, cfg_target_feature, "1.27.0", Some(29717), None), |
| // Allows `#[target_feature(...)]`. |
| (accepted, target_feature, "1.27.0", None, None), |
| // Allows using `dyn Trait` as a syntax for trait objects. |
| (accepted, dyn_trait, "1.27.0", Some(44662), None), |
| // Allows `#[must_use]` on functions, and introduces must-use operators (RFC 1940). |
| (accepted, fn_must_use, "1.27.0", Some(43302), None), |
| // Allows use of the `:lifetime` macro fragment specifier. |
| (accepted, macro_lifetime_matcher, "1.27.0", Some(34303), None), |
| // Allows `#[test]` functions where the return type implements `Termination` (RFC 1937). |
| (accepted, termination_trait_test, "1.27.0", Some(48854), None), |
| // Allows the `#[global_allocator]` attribute. |
| (accepted, global_allocator, "1.28.0", Some(27389), None), |
| // Allows `#[repr(transparent)]` attribute on newtype structs. |
| (accepted, repr_transparent, "1.28.0", Some(43036), None), |
| // Allows procedural macros in `proc-macro` crates. |
| (accepted, proc_macro, "1.29.0", Some(38356), None), |
| // Allows `foo.rs` as an alternative to `foo/mod.rs`. |
| (accepted, non_modrs_mods, "1.30.0", Some(44660), None), |
| // Allows use of the `:vis` macro fragment specifier |
| (accepted, macro_vis_matcher, "1.30.0", Some(41022), None), |
| // Allows importing and reexporting macros with `use`, |
| // enables macro modularization in general. |
| (accepted, use_extern_macros, "1.30.0", Some(35896), None), |
| // Allows keywords to be escaped for use as identifiers. |
| (accepted, raw_identifiers, "1.30.0", Some(48589), None), |
| // Allows attributes scoped to tools. |
| (accepted, tool_attributes, "1.30.0", Some(44690), None), |
| // Allows multi-segment paths in attributes and derives. |
| (accepted, proc_macro_path_invoc, "1.30.0", Some(38356), None), |
| // Allows all literals in attribute lists and values of key-value pairs. |
| (accepted, attr_literals, "1.30.0", Some(34981), None), |
| // Allows inferring outlives requirements (RFC 2093). |
| (accepted, infer_outlives_requirements, "1.30.0", Some(44493), None), |
| // Allows annotating functions conforming to `fn(&PanicInfo) -> !` with `#[panic_handler]`. |
| // This defines the behavior of panics. |
| (accepted, panic_handler, "1.30.0", Some(44489), None), |
| // Allows `#[used]` to preserve symbols (see llvm.used). |
| (accepted, used, "1.30.0", Some(40289), None), |
| // Allows `crate` in paths. |
| (accepted, crate_in_paths, "1.30.0", Some(45477), None), |
| // Allows resolving absolute paths as paths from other crates. |
| (accepted, extern_absolute_paths, "1.30.0", Some(44660), None), |
| // Allows access to crate names passed via `--extern` through prelude. |
| (accepted, extern_prelude, "1.30.0", Some(44660), None), |
| // Allows parentheses in patterns. |
| (accepted, pattern_parentheses, "1.31.0", Some(51087), None), |
| // Allows the definition of `const fn` functions. |
| (accepted, min_const_fn, "1.31.0", Some(53555), None), |
| // Allows scoped lints. |
| (accepted, tool_lints, "1.31.0", Some(44690), None), |
| // Allows lifetime elision in `impl` headers. For example: |
| // + `impl<I:Iterator> Iterator for &mut Iterator` |
| // + `impl Debug for Foo<'_>` |
| (accepted, impl_header_lifetime_elision, "1.31.0", Some(15872), None), |
| // Allows `extern crate foo as bar;`. This puts `bar` into extern prelude. |
| (accepted, extern_crate_item_prelude, "1.31.0", Some(55599), None), |
| // Allows use of the `:literal` macro fragment specifier (RFC 1576). |
| (accepted, macro_literal_matcher, "1.32.0", Some(35625), None), |
| // Allows use of `?` as the Kleene "at most one" operator in macros. |
| (accepted, macro_at_most_once_rep, "1.32.0", Some(48075), None), |
| // Allows `Self` struct constructor (RFC 2302). |
| (accepted, self_struct_ctor, "1.32.0", Some(51994), None), |
| // Allows `Self` in type definitions (RFC 2300). |
| (accepted, self_in_typedefs, "1.32.0", Some(49303), None), |
| // Allows `use x::y;` to search `x` in the current scope. |
| (accepted, uniform_paths, "1.32.0", Some(53130), None), |
| // Allows integer match exhaustiveness checking (RFC 2591). |
| (accepted, exhaustive_integer_patterns, "1.33.0", Some(50907), None), |
| // Allows `use path as _;` and `extern crate c as _;`. |
| (accepted, underscore_imports, "1.33.0", Some(48216), None), |
| // Allows `#[repr(packed(N))]` attribute on structs. |
| (accepted, repr_packed, "1.33.0", Some(33158), None), |
| // Allows irrefutable patterns in `if let` and `while let` statements (RFC 2086). |
| (accepted, irrefutable_let_patterns, "1.33.0", Some(44495), None), |
| // Allows calling `const unsafe fn` inside `unsafe` blocks in `const fn` functions. |
| (accepted, min_const_unsafe_fn, "1.33.0", Some(55607), None), |
| // Allows let bindings, assignments and destructuring in `const` functions and constants. |
| // As long as control flow is not implemented in const eval, `&&` and `||` may not be used |
| // at the same time as let bindings. |
| (accepted, const_let, "1.33.0", Some(48821), None), |
| // Allows `#[cfg_attr(predicate, multiple, attributes, here)]`. |
| (accepted, cfg_attr_multi, "1.33.0", Some(54881), None), |
| // Allows top level or-patterns (`p | q`) in `if let` and `while let`. |
| (accepted, if_while_or_patterns, "1.33.0", Some(48215), None), |
| // Allows `cfg(target_vendor = "...")`. |
| (accepted, cfg_target_vendor, "1.33.0", Some(29718), None), |
| // Allows `extern crate self as foo;`. |
| // This puts local crate root into extern prelude under name `foo`. |
| (accepted, extern_crate_self, "1.34.0", Some(56409), None), |
| // Allows arbitrary delimited token streams in non-macro attributes. |
| (accepted, unrestricted_attribute_tokens, "1.34.0", Some(55208), None), |
| // Allows paths to enum variants on type aliases including `Self`. |
| (accepted, type_alias_enum_variants, "1.37.0", Some(49683), None), |
| // Allows using `#[repr(align(X))]` on enums with equivalent semantics |
| // to wrapping an enum in a wrapper struct with `#[repr(align(X))]`. |
| (accepted, repr_align_enum, "1.37.0", Some(57996), None), |
| // Allows `const _: TYPE = VALUE`. |
| (accepted, underscore_const_names, "1.37.0", Some(54912), None), |
| |
| // ------------------------------------------------------------------------- |
| // feature-group-end: accepted features |
| // ------------------------------------------------------------------------- |
| ); |
| |
| // 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 |
| Whitelisted, |
| |
| /// Builtin attribute that is only allowed at the crate level |
| CrateLevel, |
| } |
| |
| 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, |
| } |
| |
| /// 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: $name_value_str |
| } }; |
| } |
| |
| impl AttributeGate { |
| fn is_deprecated(&self) -> bool { |
| match *self { |
| Gated(Stability::Deprecated(_, _), ..) => true, |
| _ => false, |
| } |
| } |
| } |
| |
| #[derive(Copy, Clone, Debug)] |
| pub enum Stability { |
| Unstable, |
| // First argument is tracking issue link; second argument is an optional |
| // help message, which defaults to "remove this attribute" |
| Deprecated(&'static str, Option<&'static str>), |
| } |
| |
| // fn() is not Debug |
| impl std::fmt::Debug for AttributeGate { |
| fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
| match *self { |
| Gated(ref stab, name, expl, _) => |
| write!(fmt, "Gated({:?}, {}, {})", stab, name, expl), |
| Ungated => write!(fmt, "Ungated") |
| } |
| } |
| } |
| |
| macro_rules! cfg_fn { |
| ($field: ident) => {{ |
| fn f(features: &Features) -> bool { |
| features.$field |
| } |
| f as fn(&Features) -> bool |
| }} |
| } |
| |
| pub fn deprecated_attributes() -> Vec<&'static (Symbol, AttributeType, |
| AttributeTemplate, AttributeGate)> { |
| BUILTIN_ATTRIBUTES.iter().filter(|(.., gate)| gate.is_deprecated()).collect() |
| } |
| |
| pub fn is_builtin_attr_name(name: ast::Name) -> bool { |
| BUILTIN_ATTRIBUTE_MAP.get(&name).is_some() |
| } |
| |
| pub fn is_builtin_attr(attr: &ast::Attribute) -> bool { |
| attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name)).is_some() |
| } |
| |
| /// Attributes that have a special meaning to rustc or rustdoc |
| pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[ |
| // Normal attributes |
| |
| ( |
| sym::warn, |
| Normal, |
| template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#), |
| Ungated |
| ), |
| ( |
| sym::allow, |
| Normal, |
| template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#), |
| Ungated |
| ), |
| ( |
| sym::forbid, |
| Normal, |
| template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#), |
| Ungated |
| ), |
| ( |
| sym::deny, |
| Normal, |
| template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#), |
| Ungated |
| ), |
| |
| (sym::macro_use, Normal, template!(Word, List: "name1, name2, ..."), Ungated), |
| (sym::macro_export, Normal, template!(Word, List: "local_inner_macros"), Ungated), |
| (sym::plugin_registrar, Normal, template!(Word), Ungated), |
| |
| (sym::cfg, Normal, template!(List: "predicate"), Ungated), |
| (sym::cfg_attr, Normal, template!(List: "predicate, attr1, attr2, ..."), Ungated), |
| (sym::main, Normal, template!(Word), Ungated), |
| (sym::start, Normal, template!(Word), Ungated), |
| (sym::repr, Normal, template!(List: "C, packed, ..."), Ungated), |
| (sym::path, Normal, template!(NameValueStr: "file"), Ungated), |
| (sym::automatically_derived, Normal, template!(Word), Ungated), |
| (sym::no_mangle, Whitelisted, template!(Word), Ungated), |
| (sym::no_link, Normal, template!(Word), Ungated), |
| (sym::derive, Normal, template!(List: "Trait1, Trait2, ..."), Ungated), |
| ( |
| sym::should_panic, |
| Normal, |
| template!(Word, List: r#"expected = "reason"#, NameValueStr: "reason"), |
| Ungated |
| ), |
| (sym::ignore, Normal, template!(Word, NameValueStr: "reason"), Ungated), |
| (sym::no_implicit_prelude, Normal, template!(Word), Ungated), |
| (sym::reexport_test_harness_main, Normal, template!(NameValueStr: "name"), Ungated), |
| (sym::link_args, Normal, template!(NameValueStr: "args"), Gated(Stability::Unstable, |
| sym::link_args, |
| "the `link_args` attribute is experimental and not \ |
| portable across platforms, it is recommended to \ |
| use `#[link(name = \"foo\")] instead", |
| cfg_fn!(link_args))), |
| (sym::macro_escape, Normal, template!(Word), Ungated), |
| |
| // RFC #1445. |
| (sym::structural_match, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::structural_match, |
| "the semantics of constant patterns is \ |
| not yet settled", |
| cfg_fn!(structural_match))), |
| |
| // RFC #2008 |
| (sym::non_exhaustive, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::non_exhaustive, |
| "non exhaustive is an experimental feature", |
| cfg_fn!(non_exhaustive))), |
| |
| // RFC #1268 |
| (sym::marker, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::marker_trait_attr, |
| "marker traits is an experimental feature", |
| cfg_fn!(marker_trait_attr))), |
| |
| (sym::plugin, CrateLevel, template!(List: "name|name(args)"), Gated(Stability::Unstable, |
| sym::plugin, |
| "compiler plugins are experimental \ |
| and possibly buggy", |
| cfg_fn!(plugin))), |
| |
| (sym::no_std, CrateLevel, template!(Word), Ungated), |
| (sym::no_core, CrateLevel, template!(Word), Gated(Stability::Unstable, |
| sym::no_core, |
| "no_core is experimental", |
| cfg_fn!(no_core))), |
| (sym::lang, Normal, template!(NameValueStr: "name"), Gated(Stability::Unstable, |
| sym::lang_items, |
| "language items are subject to change", |
| cfg_fn!(lang_items))), |
| (sym::linkage, Whitelisted, template!(NameValueStr: "external|internal|..."), |
| Gated(Stability::Unstable, |
| sym::linkage, |
| "the `linkage` attribute is experimental \ |
| and not portable across platforms", |
| cfg_fn!(linkage))), |
| (sym::thread_local, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::thread_local, |
| "`#[thread_local]` is an experimental feature, and does \ |
| not currently handle destructors", |
| cfg_fn!(thread_local))), |
| |
| (sym::rustc_on_unimplemented, Whitelisted, template!(List: |
| r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#, |
| NameValueStr: "message"), |
| Gated(Stability::Unstable, |
| sym::on_unimplemented, |
| "the `#[rustc_on_unimplemented]` attribute \ |
| is an experimental feature", |
| cfg_fn!(on_unimplemented))), |
| (sym::rustc_const_unstable, Normal, template!(List: r#"feature = "name""#), |
| Gated(Stability::Unstable, |
| sym::rustc_const_unstable, |
| "the `#[rustc_const_unstable]` attribute \ |
| is an internal feature", |
| cfg_fn!(rustc_const_unstable))), |
| (sym::default_lib_allocator, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::allocator_internals, |
| "the `#[default_lib_allocator]` \ |
| attribute is an experimental feature", |
| cfg_fn!(allocator_internals))), |
| (sym::needs_allocator, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::allocator_internals, |
| "the `#[needs_allocator]` \ |
| attribute is an experimental \ |
| feature", |
| cfg_fn!(allocator_internals))), |
| (sym::panic_runtime, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::panic_runtime, |
| "the `#[panic_runtime]` attribute is \ |
| an experimental feature", |
| cfg_fn!(panic_runtime))), |
| (sym::needs_panic_runtime, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::needs_panic_runtime, |
| "the `#[needs_panic_runtime]` \ |
| attribute is an experimental \ |
| feature", |
| cfg_fn!(needs_panic_runtime))), |
| (sym::rustc_outlives, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_outlives]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_variance, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_variance]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_layout, Normal, template!(List: "field1, field2, ..."), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_layout]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_layout_scalar_valid_range_start, Whitelisted, template!(List: "value"), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_layout_scalar_valid_range_start]` attribute \ |
| is just used to enable niche optimizations in libcore \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_layout_scalar_valid_range_end, Whitelisted, template!(List: "value"), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_layout_scalar_valid_range_end]` attribute \ |
| is just used to enable niche optimizations in libcore \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_nonnull_optimization_guaranteed, Whitelisted, template!(Word), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_nonnull_optimization_guaranteed]` attribute \ |
| is just used to enable niche optimizations in libcore \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_regions, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_regions]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_error, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_error]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_dump_user_substs, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "this attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_if_this_changed, Whitelisted, template!(Word, List: "DepNode"), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_if_this_changed]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_then_this_would_need, Whitelisted, template!(List: "DepNode"), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_if_this_changed]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_dirty, Whitelisted, template!(List: r#"cfg = "...", /*opt*/ label = "...", |
| /*opt*/ except = "...""#), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_dirty]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_clean, Whitelisted, template!(List: r#"cfg = "...", /*opt*/ label = "...", |
| /*opt*/ except = "...""#), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_clean]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ( |
| sym::rustc_partition_reused, |
| Whitelisted, |
| template!(List: r#"cfg = "...", module = "...""#), |
| Gated( |
| Stability::Unstable, |
| sym::rustc_attrs, |
| "this attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs) |
| ) |
| ), |
| ( |
| sym::rustc_partition_codegened, |
| Whitelisted, |
| template!(List: r#"cfg = "...", module = "...""#), |
| Gated( |
| Stability::Unstable, |
| sym::rustc_attrs, |
| "this attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs), |
| ) |
| ), |
| (sym::rustc_expected_cgu_reuse, Whitelisted, template!(List: r#"cfg = "...", module = "...", |
| kind = "...""#), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "this attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_synthetic, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "this attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_symbol_name, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "internal rustc attributes will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_def_path, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "internal rustc attributes will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_mir, Whitelisted, template!(List: "arg1, arg2, ..."), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_mir]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ( |
| sym::rustc_inherit_overflow_checks, |
| Whitelisted, |
| template!(Word), |
| Gated( |
| Stability::Unstable, |
| sym::rustc_attrs, |
| "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", |
| cfg_fn!(rustc_attrs), |
| ) |
| ), |
| |
| (sym::rustc_dump_program_clauses, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_dump_program_clauses]` \ |
| attribute is just used for rustc unit \ |
| tests and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_dump_env_program_clauses, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_dump_env_program_clauses]` \ |
| attribute is just used for rustc unit \ |
| tests and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_object_lifetime_default, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_object_lifetime_default]` \ |
| attribute is just used for rustc unit \ |
| tests and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_test_marker, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "the `#[rustc_test_marker]` attribute \ |
| is used internally to track tests", |
| cfg_fn!(rustc_attrs))), |
| (sym::rustc_macro_transparency, Whitelisted, template!(NameValueStr: |
| "transparent|semitransparent|opaque"), |
| Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "used internally for testing macro hygiene", |
| cfg_fn!(rustc_attrs))), |
| (sym::compiler_builtins, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::compiler_builtins, |
| "the `#[compiler_builtins]` attribute is used to \ |
| identify the `compiler_builtins` crate which \ |
| contains compiler-rt intrinsics and will never be \ |
| stable", |
| cfg_fn!(compiler_builtins))), |
| (sym::sanitizer_runtime, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::sanitizer_runtime, |
| "the `#[sanitizer_runtime]` attribute is used to \ |
| identify crates that contain the runtime of a \ |
| sanitizer and will never be stable", |
| cfg_fn!(sanitizer_runtime))), |
| (sym::profiler_runtime, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::profiler_runtime, |
| "the `#[profiler_runtime]` attribute is used to \ |
| identify the `profiler_builtins` crate which \ |
| contains the profiler runtime and will never be \ |
| stable", |
| cfg_fn!(profiler_runtime))), |
| |
| (sym::allow_internal_unstable, Normal, template!(Word, List: "feat1, feat2, ..."), |
| Gated(Stability::Unstable, |
| sym::allow_internal_unstable, |
| EXPLAIN_ALLOW_INTERNAL_UNSTABLE, |
| cfg_fn!(allow_internal_unstable))), |
| |
| (sym::allow_internal_unsafe, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::allow_internal_unsafe, |
| EXPLAIN_ALLOW_INTERNAL_UNSAFE, |
| cfg_fn!(allow_internal_unsafe))), |
| |
| (sym::fundamental, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::fundamental, |
| "the `#[fundamental]` attribute \ |
| is an experimental feature", |
| cfg_fn!(fundamental))), |
| |
| (sym::proc_macro_derive, Normal, template!(List: "TraitName, \ |
| /*opt*/ attributes(name1, name2, ...)"), |
| Ungated), |
| |
| (sym::rustc_allocator, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "internal implementation detail", |
| cfg_fn!(rustc_attrs))), |
| |
| (sym::rustc_allocator_nounwind, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "internal implementation detail", |
| cfg_fn!(rustc_attrs))), |
| |
| (sym::rustc_builtin_macro, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "internal implementation detail", |
| cfg_fn!(rustc_attrs))), |
| |
| (sym::rustc_promotable, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "internal implementation detail", |
| cfg_fn!(rustc_attrs))), |
| |
| (sym::rustc_allow_const_fn_ptr, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "internal implementation detail", |
| cfg_fn!(rustc_attrs))), |
| |
| (sym::rustc_dummy, Normal, template!(Word /* doesn't matter*/), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "used by the test suite", |
| cfg_fn!(rustc_attrs))), |
| |
| // FIXME: #14408 whitelist docs since rustdoc looks at them |
| ( |
| sym::doc, |
| Whitelisted, |
| template!(List: "hidden|inline|...", NameValueStr: "string"), |
| Ungated |
| ), |
| |
| // FIXME: #14406 these are processed in codegen, which happens after the |
| // lint pass |
| (sym::cold, Whitelisted, template!(Word), Ungated), |
| (sym::naked, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::naked_functions, |
| "the `#[naked]` attribute \ |
| is an experimental feature", |
| cfg_fn!(naked_functions))), |
| (sym::ffi_returns_twice, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::ffi_returns_twice, |
| "the `#[ffi_returns_twice]` attribute \ |
| is an experimental feature", |
| cfg_fn!(ffi_returns_twice))), |
| (sym::target_feature, Whitelisted, template!(List: r#"enable = "name""#), Ungated), |
| (sym::export_name, Whitelisted, template!(NameValueStr: "name"), Ungated), |
| (sym::inline, Whitelisted, template!(Word, List: "always|never"), Ungated), |
| (sym::link, Whitelisted, template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", |
| /*opt*/ cfg = "...""#), Ungated), |
| (sym::link_name, Whitelisted, template!(NameValueStr: "name"), Ungated), |
| (sym::link_section, Whitelisted, template!(NameValueStr: "name"), Ungated), |
| (sym::no_builtins, Whitelisted, template!(Word), Ungated), |
| (sym::no_debug, Whitelisted, template!(Word), Gated( |
| Stability::Deprecated("https://github.com/rust-lang/rust/issues/29721", None), |
| sym::no_debug, |
| "the `#[no_debug]` attribute was an experimental feature that has been \ |
| deprecated due to lack of demand", |
| cfg_fn!(no_debug))), |
| ( |
| sym::omit_gdb_pretty_printer_section, |
| Whitelisted, |
| template!(Word), |
| Gated( |
| Stability::Unstable, |
| sym::omit_gdb_pretty_printer_section, |
| "the `#[omit_gdb_pretty_printer_section]` \ |
| attribute is just used for the Rust test \ |
| suite", |
| cfg_fn!(omit_gdb_pretty_printer_section) |
| ) |
| ), |
| (sym::may_dangle, |
| Normal, |
| template!(Word), |
| Gated(Stability::Unstable, |
| sym::dropck_eyepatch, |
| "`may_dangle` has unstable semantics and may be removed in the future", |
| cfg_fn!(dropck_eyepatch))), |
| (sym::unwind, Whitelisted, template!(List: "allowed|aborts"), Gated(Stability::Unstable, |
| sym::unwind_attributes, |
| "`#[unwind]` is experimental", |
| cfg_fn!(unwind_attributes))), |
| (sym::used, Whitelisted, template!(Word), Ungated), |
| |
| // used in resolve |
| (sym::prelude_import, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::prelude_import, |
| "`#[prelude_import]` is for use by rustc only", |
| cfg_fn!(prelude_import))), |
| |
| // FIXME: #14407 these are only looked at on-demand so we can't |
| // guarantee they'll have already been checked |
| ( |
| sym::rustc_deprecated, |
| Whitelisted, |
| template!(List: r#"since = "version", reason = "...""#), |
| Ungated |
| ), |
| (sym::must_use, Whitelisted, template!(Word, NameValueStr: "reason"), Ungated), |
| ( |
| sym::stable, |
| Whitelisted, |
| template!(List: r#"feature = "name", since = "version""#), |
| Ungated |
| ), |
| ( |
| sym::unstable, |
| Whitelisted, |
| template!(List: r#"feature = "name", reason = "...", issue = "N""#), |
| Ungated |
| ), |
| (sym::deprecated, |
| Normal, |
| template!( |
| Word, |
| List: r#"/*opt*/ since = "version", /*opt*/ note = "reason""#, |
| NameValueStr: "reason" |
| ), |
| Ungated |
| ), |
| |
| (sym::rustc_paren_sugar, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::unboxed_closures, |
| "unboxed_closures are still evolving", |
| cfg_fn!(unboxed_closures))), |
| |
| (sym::windows_subsystem, Whitelisted, template!(NameValueStr: "windows|console"), Ungated), |
| |
| (sym::proc_macro_attribute, Normal, template!(Word), Ungated), |
| (sym::proc_macro, Normal, template!(Word), Ungated), |
| |
| (sym::rustc_proc_macro_decls, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "used internally by rustc", |
| cfg_fn!(rustc_attrs))), |
| |
| (sym::allow_fail, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::allow_fail, |
| "allow_fail attribute is currently unstable", |
| cfg_fn!(allow_fail))), |
| |
| (sym::rustc_std_internal_symbol, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "this is an internal attribute that will \ |
| never be stable", |
| cfg_fn!(rustc_attrs))), |
| |
| // whitelists "identity-like" conversion methods to suggest on type mismatch |
| (sym::rustc_conversion_suggestion, Whitelisted, template!(Word), Gated(Stability::Unstable, |
| sym::rustc_attrs, |
| "this is an internal attribute that will \ |
| never be stable", |
| cfg_fn!(rustc_attrs))), |
| |
| ( |
| sym::rustc_args_required_const, |
| Whitelisted, |
| template!(List: "N"), |
| Gated(Stability::Unstable, sym::rustc_attrs, "never will be stable", |
| cfg_fn!(rustc_attrs)) |
| ), |
| // RFC 2070 |
| (sym::panic_handler, Normal, template!(Word), Ungated), |
| |
| (sym::alloc_error_handler, Normal, template!(Word), Gated(Stability::Unstable, |
| sym::alloc_error_handler, |
| "`#[alloc_error_handler]` is an unstable feature", |
| cfg_fn!(alloc_error_handler))), |
| |
| // RFC 2412 |
| (sym::optimize, Whitelisted, template!(List: "size|speed"), Gated(Stability::Unstable, |
| sym::optimize_attribute, |
| "`#[optimize]` attribute is an unstable feature", |
| cfg_fn!(optimize_attribute))), |
| |
| // Crate level attributes |
| (sym::crate_name, CrateLevel, template!(NameValueStr: "name"), Ungated), |
| (sym::crate_type, CrateLevel, template!(NameValueStr: "bin|lib|..."), Ungated), |
| (sym::crate_id, CrateLevel, template!(NameValueStr: "ignored"), Ungated), |
| (sym::feature, CrateLevel, template!(List: "name1, name1, ..."), Ungated), |
| (sym::no_start, CrateLevel, template!(Word), Ungated), |
| (sym::no_main, CrateLevel, template!(Word), Ungated), |
| (sym::recursion_limit, CrateLevel, template!(NameValueStr: "N"), Ungated), |
| (sym::type_length_limit, CrateLevel, template!(NameValueStr: "N"), Ungated), |
| (sym::test_runner, CrateLevel, template!(List: "path"), Gated(Stability::Unstable, |
| sym::custom_test_frameworks, |
| "custom test frameworks are an unstable feature", |
| cfg_fn!(custom_test_frameworks))), |
| ]; |
| |
| pub type BuiltinAttribute = (Symbol, AttributeType, AttributeTemplate, AttributeGate); |
| |
| 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 |
| }; |
| } |
| |
| // cfg(...)'s that are feature gated |
| const GATED_CFGS: &[(Symbol, Symbol, fn(&Features) -> bool)] = &[ |
| // (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::rustdoc, sym::doc_cfg, cfg_fn!(doc_cfg)), |
| (sym::doctest, sym::cfg_doctest, cfg_fn!(cfg_doctest)), |
| ]; |
| |
| #[derive(Debug)] |
| pub struct GatedCfg { |
| span: Span, |
| index: usize, |
| } |
| |
| impl GatedCfg { |
| pub fn gate(cfg: &ast::MetaItem) -> Option<GatedCfg> { |
| GATED_CFGS.iter() |
| .position(|info| cfg.check_name(info.0)) |
| .map(|idx| { |
| GatedCfg { |
| span: cfg.span, |
| index: idx |
| } |
| }) |
| } |
| |
| pub fn check_and_emit(&self, sess: &ParseSess, features: &Features) { |
| let (cfg, feature, has_feature) = GATED_CFGS[self.index]; |
| if !has_feature(features) && !self.span.allows_unstable(feature) { |
| let explain = format!("`cfg({})` is experimental and subject to change", cfg); |
| emit_feature_err(sess, feature, self.span, GateIssue::Language, &explain); |
| } |
| } |
| } |
| |
| struct Context<'a> { |
| features: &'a Features, |
| parse_sess: &'a ParseSess, |
| plugin_attributes: &'a [(Symbol, AttributeType)], |
| } |
| |
| macro_rules! gate_feature_fn { |
| ($cx: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr, $level: expr) => {{ |
| let (cx, has_feature, span, |
| name, explain, level) = ($cx, $has_feature, $span, $name, $explain, $level); |
| let has_feature: bool = has_feature(&$cx.features); |
| debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature); |
| if !has_feature && !span.allows_unstable($name) { |
| leveled_feature_err(cx.parse_sess, name, span, GateIssue::Language, explain, level) |
| .emit(); |
| } |
| }} |
| } |
| |
| macro_rules! gate_feature { |
| ($cx: expr, $feature: ident, $span: expr, $explain: expr) => { |
| gate_feature_fn!($cx, |x:&Features| x.$feature, $span, |
| sym::$feature, $explain, GateStrength::Hard) |
| }; |
| ($cx: expr, $feature: ident, $span: expr, $explain: expr, $level: expr) => { |
| gate_feature_fn!($cx, |x:&Features| x.$feature, $span, |
| sym::$feature, $explain, $level) |
| }; |
| } |
| |
| impl<'a> Context<'a> { |
| fn check_attribute( |
| &self, |
| attr: &ast::Attribute, |
| attr_info: Option<&BuiltinAttribute>, |
| is_macro: bool |
| ) { |
| debug!("check_attribute(attr = {:?})", attr); |
| if let Some(&(name, ty, _template, ref gateage)) = attr_info { |
| if let Gated(_, name, desc, ref has_feature) = *gateage { |
| if !attr.span.allows_unstable(name) { |
| gate_feature_fn!( |
| self, has_feature, attr.span, name, desc, GateStrength::Hard |
| ); |
| } |
| } else if name == sym::doc { |
| if let Some(content) = attr.meta_item_list() { |
| if content.iter().any(|c| c.check_name(sym::include)) { |
| gate_feature!(self, external_doc, attr.span, |
| "`#[doc(include = \"...\")]` is experimental" |
| ); |
| } |
| } |
| } |
| debug!("check_attribute: {:?} is builtin, {:?}, {:?}", attr.path, ty, gateage); |
| return; |
| } else { |
| for segment in &attr.path.segments { |
| if segment.ident.as_str().starts_with("rustc") { |
| let msg = "attributes starting with `rustc` are \ |
| reserved for use by the `rustc` compiler"; |
| gate_feature!(self, rustc_attrs, segment.ident.span, msg); |
| } |
| } |
| } |
| for &(n, ty) in self.plugin_attributes { |
| if attr.path == n { |
| // Plugins can't gate attributes, so we don't check for it |
| // unlike the code above; we only use this loop to |
| // short-circuit to avoid the checks below. |
| debug!("check_attribute: {:?} is registered by a plugin, {:?}", attr.path, ty); |
| return; |
| } |
| } |
| if !is_macro && !attr::is_known(attr) { |
| // Only run the custom attribute lint during regular feature gate |
| // checking. Macro gating runs before the plugin attributes are |
| // registered, so we skip this in that case. |
| let msg = format!("the attribute `{}` is currently unknown to the compiler and \ |
| may have meaning added to it in the future", attr.path); |
| gate_feature!(self, custom_attribute, attr.span, &msg); |
| } |
| } |
| } |
| |
| pub fn check_attribute(attr: &ast::Attribute, parse_sess: &ParseSess, features: &Features) { |
| let cx = Context { features, parse_sess, plugin_attributes: &[] }; |
| cx.check_attribute( |
| attr, |
| attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name).map(|a| *a)), |
| true |
| ); |
| } |
| |
| fn find_lang_feature_issue(feature: Symbol) -> Option<u32> { |
| if let Some(info) = ACTIVE_FEATURES.iter().find(|t| t.0 == feature) { |
| let issue = info.2; |
| // FIXME (#28244): enforce that active features have issue numbers |
| // assert!(issue.is_some()) |
| issue |
| } else { |
| // search in Accepted, Removed, or Stable Removed features |
| let found = ACCEPTED_FEATURES.iter().chain(REMOVED_FEATURES).chain(STABLE_REMOVED_FEATURES) |
| .find(|t| t.0 == feature); |
| match found { |
| Some(&(_, _, issue, _)) => issue, |
| None => panic!("Feature `{}` is not declared anywhere", feature), |
| } |
| } |
| } |
| |
| pub enum GateIssue { |
| Language, |
| Library(Option<u32>) |
| } |
| |
| #[derive(Debug, Copy, Clone, PartialEq)] |
| pub enum GateStrength { |
| /// A hard error. (Most feature gates should use this.) |
| Hard, |
| /// Only a warning. (Use this only as backwards-compatibility demands.) |
| Soft, |
| } |
| |
| pub fn emit_feature_err( |
| sess: &ParseSess, |
| feature: Symbol, |
| span: Span, |
| issue: GateIssue, |
| explain: &str, |
| ) { |
| feature_err(sess, feature, span, issue, explain).emit(); |
| } |
| |
| pub fn feature_err<'a, S: Into<MultiSpan>>( |
| sess: &'a ParseSess, |
| feature: Symbol, |
| span: S, |
| issue: GateIssue, |
| explain: &str, |
| ) -> DiagnosticBuilder<'a> { |
| leveled_feature_err(sess, feature, span, issue, explain, GateStrength::Hard) |
| } |
| |
| fn leveled_feature_err<'a, S: Into<MultiSpan>>( |
| sess: &'a ParseSess, |
| feature: Symbol, |
| span: S, |
| issue: GateIssue, |
| explain: &str, |
| level: GateStrength, |
| ) -> DiagnosticBuilder<'a> { |
| let diag = &sess.span_diagnostic; |
| |
| let issue = match issue { |
| GateIssue::Language => find_lang_feature_issue(feature), |
| GateIssue::Library(lib) => lib, |
| }; |
| |
| let mut err = match level { |
| GateStrength::Hard => { |
| diag.struct_span_err_with_code(span, explain, stringify_error_code!(E0658)) |
| } |
| GateStrength::Soft => diag.struct_span_warn(span, explain), |
| }; |
| |
| match issue { |
| None | Some(0) => {} // We still accept `0` as a stand-in for backwards compatibility |
| Some(n) => { |
| err.note(&format!( |
| "for more information, see https://github.com/rust-lang/rust/issues/{}", |
| n, |
| )); |
| } |
| } |
| |
| // #23973: do not suggest `#![feature(...)]` if we are in beta/stable |
| if sess.unstable_features.is_nightly_build() { |
| err.help(&format!("add `#![feature({})]` to the crate attributes to enable", feature)); |
| } |
| |
| // If we're on stable and only emitting a "soft" warning, add a note to |
| // clarify that the feature isn't "on" (rather than being on but |
| // warning-worthy). |
| if !sess.unstable_features.is_nightly_build() && level == GateStrength::Soft { |
| err.help("a nightly build of the compiler is required to enable this feature"); |
| } |
| |
| err |
| |
| } |
| |
| const EXPLAIN_BOX_SYNTAX: &str = |
| "box expression syntax is experimental; you can call `Box::new` instead"; |
| |
| pub const EXPLAIN_STMT_ATTR_SYNTAX: &str = |
| "attributes on expressions are experimental"; |
| |
| pub const EXPLAIN_ALLOW_INTERNAL_UNSTABLE: &str = |
| "allow_internal_unstable side-steps feature gating and stability checks"; |
| pub const EXPLAIN_ALLOW_INTERNAL_UNSAFE: &str = |
| "allow_internal_unsafe side-steps the unsafe_code lint"; |
| |
| pub const EXPLAIN_UNSIZED_TUPLE_COERCION: &str = |
| "unsized tuple coercion is not stable enough for use and is subject to change"; |
| |
| struct PostExpansionVisitor<'a> { |
| context: &'a Context<'a>, |
| builtin_attributes: &'static FxHashMap<Symbol, &'static BuiltinAttribute>, |
| } |
| |
| macro_rules! gate_feature_post { |
| ($cx: expr, $feature: ident, $span: expr, $explain: expr) => {{ |
| let (cx, span) = ($cx, $span); |
| if !span.allows_unstable(sym::$feature) { |
| gate_feature!(cx.context, $feature, span, $explain) |
| } |
| }}; |
| ($cx: expr, $feature: ident, $span: expr, $explain: expr, $level: expr) => {{ |
| let (cx, span) = ($cx, $span); |
| if !span.allows_unstable(sym::$feature) { |
| gate_feature!(cx.context, $feature, span, $explain, $level) |
| } |
| }} |
| } |
| |
| impl<'a> PostExpansionVisitor<'a> { |
| fn check_abi(&self, abi: Abi, span: Span) { |
| match abi { |
| Abi::RustIntrinsic => { |
| gate_feature_post!(&self, intrinsics, span, |
| "intrinsics are subject to change"); |
| }, |
| Abi::PlatformIntrinsic => { |
| gate_feature_post!(&self, platform_intrinsics, span, |
| "platform intrinsics are experimental and possibly buggy"); |
| }, |
| Abi::Vectorcall => { |
| gate_feature_post!(&self, abi_vectorcall, span, |
| "vectorcall is experimental and subject to change"); |
| }, |
| Abi::Thiscall => { |
| gate_feature_post!(&self, abi_thiscall, span, |
| "thiscall is experimental and subject to change"); |
| }, |
| Abi::RustCall => { |
| gate_feature_post!(&self, unboxed_closures, span, |
| "rust-call ABI is subject to change"); |
| }, |
| Abi::PtxKernel => { |
| gate_feature_post!(&self, abi_ptx, span, |
| "PTX ABIs are experimental and subject to change"); |
| }, |
| Abi::Unadjusted => { |
| gate_feature_post!(&self, abi_unadjusted, span, |
| "unadjusted ABI is an implementation detail and perma-unstable"); |
| }, |
| Abi::Msp430Interrupt => { |
| gate_feature_post!(&self, abi_msp430_interrupt, span, |
| "msp430-interrupt ABI is experimental and subject to change"); |
| }, |
| Abi::X86Interrupt => { |
| gate_feature_post!(&self, abi_x86_interrupt, span, |
| "x86-interrupt ABI is experimental and subject to change"); |
| }, |
| Abi::AmdGpuKernel => { |
| gate_feature_post!(&self, abi_amdgpu_kernel, span, |
| "amdgpu-kernel ABI is experimental and subject to change"); |
| }, |
| // Stable |
| Abi::Cdecl | |
| Abi::Stdcall | |
| Abi::Fastcall | |
| Abi::Aapcs | |
| Abi::Win64 | |
| Abi::SysV64 | |
| Abi::Rust | |
| Abi::C | |
| Abi::System => {} |
| } |
| } |
| } |
| |
| impl<'a> Visitor<'a> for PostExpansionVisitor<'a> { |
| fn visit_attribute(&mut self, attr: &ast::Attribute) { |
| let attr_info = attr.ident().and_then(|ident| { |
| self.builtin_attributes.get(&ident.name).map(|a| *a) |
| }); |
| |
| // Check for gated attributes. |
| self.context.check_attribute(attr, attr_info, false); |
| |
| if attr.check_name(sym::doc) { |
| if let Some(content) = attr.meta_item_list() { |
| if content.len() == 1 && content[0].check_name(sym::cfg) { |
| gate_feature_post!(&self, doc_cfg, attr.span, |
| "`#[doc(cfg(...))]` is experimental" |
| ); |
| } else if content.iter().any(|c| c.check_name(sym::masked)) { |
| gate_feature_post!(&self, doc_masked, attr.span, |
| "`#[doc(masked)]` is experimental" |
| ); |
| } else if content.iter().any(|c| c.check_name(sym::spotlight)) { |
| gate_feature_post!(&self, doc_spotlight, attr.span, |
| "`#[doc(spotlight)]` is experimental" |
| ); |
| } else if content.iter().any(|c| c.check_name(sym::alias)) { |
| gate_feature_post!(&self, doc_alias, attr.span, |
| "`#[doc(alias = \"...\")]` is experimental" |
| ); |
| } else if content.iter().any(|c| c.check_name(sym::keyword)) { |
| gate_feature_post!(&self, doc_keyword, attr.span, |
| "`#[doc(keyword = \"...\")]` is experimental" |
| ); |
| } |
| } |
| } |
| |
| match attr_info { |
| // `rustc_dummy` doesn't have any restrictions specific to built-in attributes. |
| Some(&(name, _, template, _)) if name != sym::rustc_dummy => |
| check_builtin_attribute(self.context.parse_sess, attr, name, template), |
| _ => if let Some(TokenTree::Token(token)) = attr.tokens.trees().next() { |
| if token == token::Eq { |
| // All key-value attributes are restricted to meta-item syntax. |
| attr.parse_meta(self.context.parse_sess).map_err(|mut err| err.emit()).ok(); |
| } |
| } |
| } |
| } |
| |
| fn visit_name(&mut self, sp: Span, name: ast::Name) { |
| if !name.as_str().is_ascii() { |
| gate_feature_post!( |
| &self, |
| non_ascii_idents, |
| self.context.parse_sess.source_map().def_span(sp), |
| "non-ascii idents are not fully supported" |
| ); |
| } |
| } |
| |
| fn visit_item(&mut self, i: &'a ast::Item) { |
| match i.node { |
| ast::ItemKind::ForeignMod(ref foreign_module) => { |
| self.check_abi(foreign_module.abi, i.span); |
| } |
| |
| ast::ItemKind::Fn(..) => { |
| if attr::contains_name(&i.attrs[..], sym::plugin_registrar) { |
| gate_feature_post!(&self, plugin_registrar, i.span, |
| "compiler plugins are experimental and possibly buggy"); |
| } |
| if attr::contains_name(&i.attrs[..], sym::start) { |
| gate_feature_post!(&self, start, i.span, |
| "a `#[start]` function is an experimental \ |
| feature whose signature may change \ |
| over time"); |
| } |
| if attr::contains_name(&i.attrs[..], sym::main) { |
| gate_feature_post!(&self, main, i.span, |
| "declaration of a non-standard `#[main]` \ |
| function may change over time, for now \ |
| a top-level `fn main()` is required"); |
| } |
| } |
| |
| ast::ItemKind::Struct(..) => { |
| for attr in attr::filter_by_name(&i.attrs[..], sym::repr) { |
| for item in attr.meta_item_list().unwrap_or_else(Vec::new) { |
| if item.check_name(sym::simd) { |
| gate_feature_post!(&self, repr_simd, attr.span, |
| "SIMD types are experimental and possibly buggy"); |
| } |
| } |
| } |
| } |
| |
| ast::ItemKind::Enum(ast::EnumDef{ref variants, ..}, ..) => { |
| for variant in variants { |
| match (&variant.data, &variant.disr_expr) { |
| (ast::VariantData::Unit(..), _) => {}, |
| (_, Some(disr_expr)) => |
| gate_feature_post!( |
| &self, |
| arbitrary_enum_discriminant, |
| disr_expr.value.span, |
| "discriminants on non-unit variants are experimental"), |
| _ => {}, |
| } |
| } |
| |
| let has_feature = self.context.features.arbitrary_enum_discriminant; |
| if !has_feature && !i.span.allows_unstable(sym::arbitrary_enum_discriminant) { |
| Parser::maybe_report_invalid_custom_discriminants( |
| self.context.parse_sess, |
| &variants, |
| ); |
| } |
| } |
| |
| ast::ItemKind::Impl(_, polarity, defaultness, _, _, _, _) => { |
| if polarity == ast::ImplPolarity::Negative { |
| gate_feature_post!(&self, optin_builtin_traits, |
| i.span, |
| "negative trait bounds are not yet fully implemented; \ |
| use marker types for now"); |
| } |
| |
| if let ast::Defaultness::Default = defaultness { |
| gate_feature_post!(&self, specialization, |
| i.span, |
| "specialization is unstable"); |
| } |
| } |
| |
| ast::ItemKind::Trait(ast::IsAuto::Yes, ..) => { |
| gate_feature_post!(&self, optin_builtin_traits, |
| i.span, |
| "auto traits are experimental and possibly buggy"); |
| } |
| |
| ast::ItemKind::TraitAlias(..) => { |
| gate_feature_post!( |
| &self, |
| trait_alias, |
| i.span, |
| "trait aliases are experimental" |
| ); |
| } |
| |
| ast::ItemKind::MacroDef(ast::MacroDef { legacy: false, .. }) => { |
| let msg = "`macro` is experimental"; |
| gate_feature_post!(&self, decl_macro, i.span, msg); |
| } |
| |
| ast::ItemKind::OpaqueTy(..) => { |
| gate_feature_post!( |
| &self, |
| type_alias_impl_trait, |
| i.span, |
| "`impl Trait` in type aliases is unstable" |
| ); |
| } |
| |
| _ => {} |
| } |
| |
| visit::walk_item(self, i); |
| } |
| |
| fn visit_foreign_item(&mut self, i: &'a ast::ForeignItem) { |
| match i.node { |
| ast::ForeignItemKind::Fn(..) | |
| ast::ForeignItemKind::Static(..) => { |
| let link_name = attr::first_attr_value_str_by_name(&i.attrs, sym::link_name); |
| let links_to_llvm = match link_name { |
| Some(val) => val.as_str().starts_with("llvm."), |
| _ => false |
| }; |
| if links_to_llvm { |
| gate_feature_post!(&self, link_llvm_intrinsics, i.span, |
| "linking to LLVM intrinsics is experimental"); |
| } |
| } |
| ast::ForeignItemKind::Ty => { |
| gate_feature_post!(&self, extern_types, i.span, |
| "extern types are experimental"); |
| } |
| ast::ForeignItemKind::Macro(..) => {} |
| } |
| |
| visit::walk_foreign_item(self, i) |
| } |
| |
| fn visit_ty(&mut self, ty: &'a ast::Ty) { |
| match ty.node { |
| ast::TyKind::BareFn(ref bare_fn_ty) => { |
| self.check_abi(bare_fn_ty.abi, ty.span); |
| } |
| ast::TyKind::Never => { |
| gate_feature_post!(&self, never_type, ty.span, |
| "The `!` type is experimental"); |
| } |
| _ => {} |
| } |
| visit::walk_ty(self, ty) |
| } |
| |
| fn visit_fn_ret_ty(&mut self, ret_ty: &'a ast::FunctionRetTy) { |
| if let ast::FunctionRetTy::Ty(ref output_ty) = *ret_ty { |
| if let ast::TyKind::Never = output_ty.node { |
| // Do nothing. |
| } else { |
| self.visit_ty(output_ty) |
| } |
| } |
| } |
| |
| fn visit_expr(&mut self, e: &'a ast::Expr) { |
| match e.node { |
| ast::ExprKind::Box(_) => { |
| gate_feature_post!(&self, box_syntax, e.span, EXPLAIN_BOX_SYNTAX); |
| } |
| ast::ExprKind::Type(..) => { |
| // To avoid noise about type ascription in common syntax errors, only emit if it |
| // is the *only* error. |
| if self.context.parse_sess.span_diagnostic.err_count() == 0 { |
| gate_feature_post!(&self, type_ascription, e.span, |
| "type ascription is experimental"); |
| } |
| } |
| ast::ExprKind::TryBlock(_) => { |
| gate_feature_post!(&self, try_blocks, e.span, "`try` expression is experimental"); |
| } |
| ast::ExprKind::Block(_, opt_label) => { |
| if let Some(label) = opt_label { |
| gate_feature_post!(&self, label_break_value, label.ident.span, |
| "labels on blocks are unstable"); |
| } |
| } |
| ast::ExprKind::Async(..) => { |
| gate_feature_post!(&self, async_await, e.span, "async blocks are unstable"); |
| } |
| ast::ExprKind::Await(_) => { |
| gate_feature_post!(&self, async_await, e.span, "async/await is unstable"); |
| } |
| _ => {} |
| } |
| visit::walk_expr(self, e) |
| } |
| |
| fn visit_arm(&mut self, arm: &'a ast::Arm) { |
| visit::walk_arm(self, arm) |
| } |
| |
| fn visit_pat(&mut self, pattern: &'a ast::Pat) { |
| match &pattern.node { |
| PatKind::Slice(pats) => { |
| for pat in &*pats { |
| let span = pat.span; |
| let inner_pat = match &pat.node { |
| PatKind::Ident(.., Some(pat)) => pat, |
| _ => pat, |
| }; |
| if inner_pat.is_rest() { |
| gate_feature_post!( |
| &self, |
| slice_patterns, |
| span, |
| "subslice patterns are unstable" |
| ); |
| } |
| } |
| } |
| PatKind::Box(..) => { |
| gate_feature_post!(&self, box_patterns, |
| pattern.span, |
| "box pattern syntax is experimental"); |
| } |
| PatKind::Range(_, _, Spanned { node: RangeEnd::Excluded, .. }) => { |
| gate_feature_post!(&self, exclusive_range_pattern, pattern.span, |
| "exclusive range pattern syntax is experimental"); |
| } |
| _ => {} |
| } |
| visit::walk_pat(self, pattern) |
| } |
| |
| fn visit_fn(&mut self, |
| fn_kind: FnKind<'a>, |
| fn_decl: &'a ast::FnDecl, |
| span: Span, |
| _node_id: NodeId) { |
| if let Some(header) = fn_kind.header() { |
| // Check for const fn and async fn declarations. |
| if header.asyncness.node.is_async() { |
| gate_feature_post!(&self, async_await, span, "async fn is unstable"); |
| } |
| |
| // Stability of const fn methods are covered in |
| // `visit_trait_item` and `visit_impl_item` below; this is |
| // because default methods don't pass through this point. |
| self.check_abi(header.abi, span); |
| } |
| |
| if fn_decl.c_variadic { |
| gate_feature_post!(&self, c_variadic, span, "C-variadic functions are unstable"); |
| } |
| |
| visit::walk_fn(self, fn_kind, fn_decl, span) |
| } |
| |
| fn visit_generic_param(&mut self, param: &'a GenericParam) { |
| match param.kind { |
| GenericParamKind::Const { .. } => |
| gate_feature_post!(&self, const_generics, param.ident.span, |
| "const generics are unstable"), |
| _ => {} |
| } |
| visit::walk_generic_param(self, param) |
| } |
| |
| fn visit_assoc_ty_constraint(&mut self, constraint: &'a AssocTyConstraint) { |
| match constraint.kind { |
| AssocTyConstraintKind::Bound { .. } => |
| gate_feature_post!(&self, associated_type_bounds, constraint.span, |
| "associated type bounds are unstable"), |
| _ => {} |
| } |
| visit::walk_assoc_ty_constraint(self, constraint) |
| } |
| |
| fn visit_trait_item(&mut self, ti: &'a ast::TraitItem) { |
| match ti.node { |
| ast::TraitItemKind::Method(ref sig, ref block) => { |
| if block.is_none() { |
| self.check_abi(sig.header.abi, ti.span); |
| } |
| if sig.header.asyncness.node.is_async() { |
| gate_feature_post!(&self, async_await, ti.span, "async fn is unstable"); |
| } |
| if sig.decl.c_variadic { |
| gate_feature_post!(&self, c_variadic, ti.span, |
| "C-variadic functions are unstable"); |
| } |
| if sig.header.constness.node == ast::Constness::Const { |
| gate_feature_post!(&self, const_fn, ti.span, "const fn is unstable"); |
| } |
| } |
| ast::TraitItemKind::Type(_, ref default) => { |
| // We use three if statements instead of something like match guards so that all |
| // of these errors can be emitted if all cases apply. |
| if default.is_some() { |
| gate_feature_post!(&self, associated_type_defaults, ti.span, |
| "associated type defaults are unstable"); |
| } |
| if !ti.generics.params.is_empty() { |
| gate_feature_post!(&self, generic_associated_types, ti.span, |
| "generic associated types are unstable"); |
| } |
| if !ti.generics.where_clause.predicates.is_empty() { |
| gate_feature_post!(&self, generic_associated_types, ti.span, |
| "where clauses on associated types are unstable"); |
| } |
| } |
| _ => {} |
| } |
| visit::walk_trait_item(self, ti) |
| } |
| |
| fn visit_impl_item(&mut self, ii: &'a ast::ImplItem) { |
| if ii.defaultness == ast::Defaultness::Default { |
| gate_feature_post!(&self, specialization, |
| ii.span, |
| "specialization is unstable"); |
| } |
| |
| match ii.node { |
| ast::ImplItemKind::Method(..) => {} |
| ast::ImplItemKind::OpaqueTy(..) => { |
| gate_feature_post!( |
| &self, |
| type_alias_impl_trait, |
| ii.span, |
| "`impl Trait` in type aliases is unstable" |
| ); |
| } |
| ast::ImplItemKind::TyAlias(_) => { |
| if !ii.generics.params.is_empty() { |
| gate_feature_post!(&self, generic_associated_types, ii.span, |
| "generic associated types are unstable"); |
| } |
| if !ii.generics.where_clause.predicates.is_empty() { |
| gate_feature_post!(&self, generic_associated_types, ii.span, |
| "where clauses on associated types are unstable"); |
| } |
| } |
| _ => {} |
| } |
| visit::walk_impl_item(self, ii) |
| } |
| |
| fn visit_vis(&mut self, vis: &'a ast::Visibility) { |
| if let ast::VisibilityKind::Crate(ast::CrateSugar::JustCrate) = vis.node { |
| gate_feature_post!(&self, crate_visibility_modifier, vis.span, |
| "`crate` visibility modifier is experimental"); |
| } |
| visit::walk_vis(self, vis) |
| } |
| } |
| |
| pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute], |
| crate_edition: Edition, allow_features: &Option<Vec<String>>) -> Features { |
| fn feature_removed(span_handler: &Handler, span: Span, reason: Option<&str>) { |
| let mut err = struct_span_err!(span_handler, span, E0557, "feature has been removed"); |
| if let Some(reason) = reason { |
| err.span_note(span, reason); |
| } else { |
| err.span_label(span, "feature has been removed"); |
| } |
| err.emit(); |
| } |
| |
| let mut features = Features::new(); |
| let mut edition_enabled_features = FxHashMap::default(); |
| |
| for &edition in ALL_EDITIONS { |
| if edition <= crate_edition { |
| // The `crate_edition` implies its respective umbrella feature-gate |
| // (i.e., `#![feature(rust_20XX_preview)]` isn't needed on edition 20XX). |
| edition_enabled_features.insert(edition.feature_name(), edition); |
| } |
| } |
| |
| for &(name, .., f_edition, set) in ACTIVE_FEATURES { |
| if let Some(f_edition) = f_edition { |
| if f_edition <= crate_edition { |
| set(&mut features, DUMMY_SP); |
| edition_enabled_features.insert(name, crate_edition); |
| } |
| } |
| } |
| |
| // Process the edition umbrella feature-gates first, to ensure |
| // `edition_enabled_features` is completed before it's queried. |
| for attr in krate_attrs { |
| if !attr.check_name(sym::feature) { |
| continue |
| } |
| |
| let list = match attr.meta_item_list() { |
| Some(list) => list, |
| None => continue, |
| }; |
| |
| for mi in list { |
| if !mi.is_word() { |
| continue; |
| } |
| |
| let name = mi.name_or_empty(); |
| |
| if let Some(edition) = ALL_EDITIONS.iter().find(|e| name == e.feature_name()) { |
| if *edition <= crate_edition { |
| continue; |
| } |
| |
| for &(name, .., f_edition, set) in ACTIVE_FEATURES { |
| if let Some(f_edition) = f_edition { |
| if f_edition <= *edition { |
| // FIXME(Manishearth) there is currently no way to set |
| // lib features by edition |
| set(&mut features, DUMMY_SP); |
| edition_enabled_features.insert(name, *edition); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| for attr in krate_attrs { |
| if !attr.check_name(sym::feature) { |
| continue |
| } |
| |
| let list = match attr.meta_item_list() { |
| Some(list) => list, |
| None => continue, |
| }; |
| |
| let bad_input = |span| { |
| struct_span_err!(span_handler, span, E0556, "malformed `feature` attribute input") |
| }; |
| |
| for mi in list { |
| let name = match mi.ident() { |
| Some(ident) if mi.is_word() => ident.name, |
| Some(ident) => { |
| bad_input(mi.span()).span_suggestion( |
| mi.span(), |
| "expected just one word", |
| format!("{}", ident.name), |
| Applicability::MaybeIncorrect, |
| ).emit(); |
| continue |
| } |
| None => { |
| bad_input(mi.span()).span_label(mi.span(), "expected just one word").emit(); |
| continue |
| } |
| }; |
| |
| if let Some(edition) = edition_enabled_features.get(&name) { |
| struct_span_warn!( |
| span_handler, |
| mi.span(), |
| E0705, |
| "the feature `{}` is included in the Rust {} edition", |
| name, |
| edition, |
| ).emit(); |
| continue; |
| } |
| |
| if ALL_EDITIONS.iter().any(|e| name == e.feature_name()) { |
| // Handled in the separate loop above. |
| continue; |
| } |
| |
| let removed = REMOVED_FEATURES.iter().find(|f| name == f.0); |
| let stable_removed = STABLE_REMOVED_FEATURES.iter().find(|f| name == f.0); |
| if let Some((.., reason)) = removed.or(stable_removed) { |
| feature_removed(span_handler, mi.span(), *reason); |
| continue; |
| } |
| |
| if let Some((_, since, ..)) = ACCEPTED_FEATURES.iter().find(|f| name == f.0) { |
| let since = Some(Symbol::intern(since)); |
| features.declared_lang_features.push((name, mi.span(), since)); |
| continue; |
| } |
| |
| if let Some(allowed) = allow_features.as_ref() { |
| if allowed.iter().find(|f| *f == name.as_str()).is_none() { |
| span_err!(span_handler, mi.span(), E0725, |
| "the feature `{}` is not in the list of allowed features", |
| name); |
| continue; |
| } |
| } |
| |
| if let Some((.., set)) = ACTIVE_FEATURES.iter().find(|f| name == f.0) { |
| set(&mut features, mi.span()); |
| features.declared_lang_features.push((name, mi.span(), None)); |
| continue; |
| } |
| |
| features.declared_lib_features.push((name, mi.span())); |
| } |
| } |
| |
| features |
| } |
| |
| pub fn check_crate(krate: &ast::Crate, |
| sess: &ParseSess, |
| features: &Features, |
| plugin_attributes: &[(Symbol, AttributeType)], |
| unstable: UnstableFeatures) { |
| maybe_stage_features(&sess.span_diagnostic, krate, unstable); |
| let ctx = Context { |
| features, |
| parse_sess: sess, |
| plugin_attributes, |
| }; |
| |
| macro_rules! gate_all { |
| ($spans:ident, $gate:ident, $msg:literal) => { |
| for span in &*sess.$spans.borrow() { gate_feature!(&ctx, $gate, *span, $msg); } |
| } |
| } |
| |
| gate_all!(param_attr_spans, param_attrs, "attributes on function parameters are unstable"); |
| gate_all!(let_chains_spans, let_chains, "`let` expressions in this position are experimental"); |
| gate_all!(async_closure_spans, async_closure, "async closures are unstable"); |
| gate_all!(yield_spans, generators, "yield syntax is experimental"); |
| |
| let visitor = &mut PostExpansionVisitor { |
| context: &ctx, |
| builtin_attributes: &*BUILTIN_ATTRIBUTE_MAP, |
| }; |
| visit::walk_crate(visitor, krate); |
| } |
| |
| #[derive(Clone, Copy, Hash)] |
| pub enum UnstableFeatures { |
| /// Hard errors for unstable features are active, as on beta/stable channels. |
| Disallow, |
| /// Allow features to be activated, as on nightly. |
| Allow, |
| /// Errors are bypassed for bootstrapping. This is required any time |
| /// during the build that feature-related lints are set to warn or above |
| /// because the build turns on warnings-as-errors and uses lots of unstable |
| /// features. As a result, this is always required for building Rust itself. |
| Cheat |
| } |
| |
| impl UnstableFeatures { |
| pub fn from_environment() -> UnstableFeatures { |
| // Whether this is a feature-staged build, i.e., on the beta or stable channel |
| let disable_unstable_features = option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some(); |
| // Whether we should enable unstable features for bootstrapping |
| let bootstrap = env::var("RUSTC_BOOTSTRAP").is_ok(); |
| match (disable_unstable_features, bootstrap) { |
| (_, true) => UnstableFeatures::Cheat, |
| (true, _) => UnstableFeatures::Disallow, |
| (false, _) => UnstableFeatures::Allow |
| } |
| } |
| |
| pub fn is_nightly_build(&self) -> bool { |
| match *self { |
| UnstableFeatures::Allow | UnstableFeatures::Cheat => true, |
| _ => false, |
| } |
| } |
| } |
| |
| fn maybe_stage_features(span_handler: &Handler, krate: &ast::Crate, |
| unstable: UnstableFeatures) { |
| let allow_features = match unstable { |
| UnstableFeatures::Allow => true, |
| UnstableFeatures::Disallow => false, |
| UnstableFeatures::Cheat => true |
| }; |
| if !allow_features { |
| for attr in &krate.attrs { |
| if attr.check_name(sym::feature) { |
| let release_channel = option_env!("CFG_RELEASE_CHANNEL").unwrap_or("(unknown)"); |
| span_err!(span_handler, attr.span, E0554, |
| "`#![feature]` may not be used on the {} release channel", |
| release_channel); |
| } |
| } |
| } |
| } |