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Diffstat (limited to 'src/libsyntax/feature_gate.rs')
| -rw-r--r-- | src/libsyntax/feature_gate.rs | 2495 |
1 files changed, 0 insertions, 2495 deletions
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs deleted file mode 100644 index bce0b07db1c..00000000000 --- a/src/libsyntax/feature_gate.rs +++ /dev/null @@ -1,2495 +0,0 @@ -//! # 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 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), - - // Allows the use of or-patterns, e.g. `0 | 1`. - (active, or_patterns, "1.38.0", Some(54883), 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::or_patterns, - 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), - // Allows free and inherent `async fn`s, `async` blocks, and `<expr>.await` expressions. - (accepted, async_await, "1.38.0", Some(50547), 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"); - } - } - _ => {} - } - 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() { - // 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.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"); - gate_all!(or_pattern_spans, or_patterns, "or-patterns 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); - } - } - } -} |