| // Copyright 2013 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| //! 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 self::AttributeType::*; |
| use self::AttributeGate::*; |
| |
| use abi::Abi; |
| use ast::{self, NodeId, PatKind, RangeEnd, RangeSyntax}; |
| use attr; |
| use codemap::Spanned; |
| use syntax_pos::Span; |
| use errors::{DiagnosticBuilder, Handler, FatalError}; |
| use visit::{self, FnKind, Visitor}; |
| use parse::ParseSess; |
| use symbol::Symbol; |
| |
| use std::env; |
| |
| macro_rules! set { |
| (proc_macro) => {{ |
| fn f(features: &mut Features, span: Span) { |
| features.declared_lib_features.push((Symbol::intern("proc_macro"), span)); |
| features.proc_macro = true; |
| } |
| f as fn(&mut Features, Span) |
| }}; |
| ($field: ident) => {{ |
| fn f(features: &mut Features, _: Span) { |
| features.$field = true; |
| } |
| f as fn(&mut Features, Span) |
| }} |
| } |
| |
| macro_rules! declare_features { |
| ($((active, $feature: ident, $ver: expr, $issue: expr),)+) => { |
| /// Represents active features that are currently being implemented or |
| /// currently being considered for addition/removal. |
| const ACTIVE_FEATURES: |
| &'static [(&'static str, &'static str, Option<u32>, fn(&mut Features, Span))] = |
| &[$((stringify!($feature), $ver, $issue, set!($feature))),+]; |
| |
| /// A set of features to be used by later passes. |
| pub struct Features { |
| /// #![feature] attrs for stable language features, for error reporting |
| pub declared_stable_lang_features: Vec<(Symbol, Span)>, |
| /// #![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_stable_lang_features: Vec::new(), |
| declared_lib_features: Vec::new(), |
| $($feature: false),+ |
| } |
| } |
| } |
| }; |
| |
| ($((removed, $feature: ident, $ver: expr, $issue: expr),)+) => { |
| /// Represents unstable features which have since been removed (it was once Active) |
| const REMOVED_FEATURES: &'static [(&'static str, &'static str, Option<u32>)] = &[ |
| $((stringify!($feature), $ver, $issue)),+ |
| ]; |
| }; |
| |
| ($((stable_removed, $feature: ident, $ver: expr, $issue: expr),)+) => { |
| /// Represents stable features which have since been removed (it was once Accepted) |
| const STABLE_REMOVED_FEATURES: &'static [(&'static str, &'static str, Option<u32>)] = &[ |
| $((stringify!($feature), $ver, $issue)),+ |
| ]; |
| }; |
| |
| ($((accepted, $feature: ident, $ver: expr, $issue: expr),)+) => { |
| /// Those language feature has since been Accepted (it was once Active) |
| const ACCEPTED_FEATURES: &'static [(&'static str, &'static str, Option<u32>)] = &[ |
| $((stringify!($feature), $ver, $issue)),+ |
| ]; |
| } |
| } |
| |
| // 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). |
| // |
| // NB: tools/tidy/src/features.rs parses this information directly out of the |
| // source, so take care when modifying it. |
| |
| declare_features! ( |
| (active, asm, "1.0.0", Some(29722)), |
| (active, concat_idents, "1.0.0", Some(29599)), |
| (active, link_args, "1.0.0", Some(29596)), |
| (active, log_syntax, "1.0.0", Some(29598)), |
| (active, non_ascii_idents, "1.0.0", Some(28979)), |
| (active, plugin_registrar, "1.0.0", Some(29597)), |
| (active, thread_local, "1.0.0", Some(29594)), |
| (active, trace_macros, "1.0.0", Some(29598)), |
| |
| // rustc internal, for now: |
| (active, intrinsics, "1.0.0", None), |
| (active, lang_items, "1.0.0", None), |
| |
| (active, link_llvm_intrinsics, "1.0.0", Some(29602)), |
| (active, linkage, "1.0.0", Some(29603)), |
| (active, quote, "1.0.0", Some(29601)), |
| (active, simd, "1.0.0", Some(27731)), |
| |
| |
| // rustc internal |
| (active, rustc_diagnostic_macros, "1.0.0", None), |
| (active, rustc_const_unstable, "1.0.0", None), |
| (active, advanced_slice_patterns, "1.0.0", Some(23121)), |
| (active, box_syntax, "1.0.0", Some(27779)), |
| (active, placement_in_syntax, "1.0.0", Some(27779)), |
| (active, unboxed_closures, "1.0.0", Some(29625)), |
| |
| (active, fundamental, "1.0.0", Some(29635)), |
| (active, main, "1.0.0", Some(29634)), |
| (active, needs_allocator, "1.4.0", Some(27389)), |
| (active, on_unimplemented, "1.0.0", Some(29628)), |
| (active, plugin, "1.0.0", Some(29597)), |
| (active, simd_ffi, "1.0.0", Some(27731)), |
| (active, start, "1.0.0", Some(29633)), |
| (active, structural_match, "1.8.0", Some(31434)), |
| (active, panic_runtime, "1.10.0", Some(32837)), |
| (active, needs_panic_runtime, "1.10.0", Some(32837)), |
| |
| // OIBIT specific features |
| (active, optin_builtin_traits, "1.0.0", Some(13231)), |
| |
| // macro reexport needs more discussion and stabilization |
| (active, macro_reexport, "1.0.0", Some(29638)), |
| |
| // Allows use of #[staged_api] |
| // rustc internal |
| (active, staged_api, "1.0.0", None), |
| |
| // Allows using #![no_core] |
| (active, no_core, "1.3.0", Some(29639)), |
| |
| // Allows using `box` in patterns; RFC 469 |
| (active, box_patterns, "1.0.0", Some(29641)), |
| |
| // Allows using the unsafe_destructor_blind_to_params attribute; |
| // RFC 1238 |
| (active, dropck_parametricity, "1.3.0", Some(28498)), |
| |
| // Allows using the may_dangle attribute; RFC 1327 |
| (active, dropck_eyepatch, "1.10.0", Some(34761)), |
| |
| // Allows the use of custom attributes; RFC 572 |
| (active, custom_attribute, "1.0.0", Some(29642)), |
| |
| // Allows the use of #[derive(Anything)] as sugar for |
| // #[derive_Anything]. |
| (active, custom_derive, "1.0.0", Some(29644)), |
| |
| // Allows the use of rustc_* attributes; RFC 572 |
| (active, rustc_attrs, "1.0.0", Some(29642)), |
| |
| // Allows the use of #[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). |
| // |
| // rustc internal |
| (active, allow_internal_unstable, "1.0.0", None), |
| |
| // Allows the use of #[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). |
| // |
| // rustc internal |
| (active, allow_internal_unsafe, "1.0.0", None), |
| |
| // #23121. Array patterns have some hazards yet. |
| (active, slice_patterns, "1.0.0", Some(23121)), |
| |
| // Allows the definition of `const fn` functions. |
| (active, const_fn, "1.2.0", Some(24111)), |
| |
| // Allows indexing into constant arrays. |
| (active, const_indexing, "1.4.0", Some(29947)), |
| |
| // Allows using #[prelude_import] on glob `use` items. |
| // |
| // rustc internal |
| (active, prelude_import, "1.2.0", None), |
| |
| // Allows default type parameters to influence type inference. |
| (active, default_type_parameter_fallback, "1.3.0", Some(27336)), |
| |
| // Allows associated type defaults |
| (active, associated_type_defaults, "1.2.0", Some(29661)), |
| |
| // allow `repr(simd)`, and importing the various simd intrinsics |
| (active, repr_simd, "1.4.0", Some(27731)), |
| |
| // Allows cfg(target_feature = "..."). |
| (active, cfg_target_feature, "1.4.0", Some(29717)), |
| |
| // allow `extern "platform-intrinsic" { ... }` |
| (active, platform_intrinsics, "1.4.0", Some(27731)), |
| |
| // allow `#[unwind]` |
| // rust runtime internal |
| (active, unwind_attributes, "1.4.0", None), |
| |
| // allow the use of `#[naked]` on functions. |
| (active, naked_functions, "1.9.0", Some(32408)), |
| |
| // allow `#[no_debug]` |
| (active, no_debug, "1.5.0", Some(29721)), |
| |
| // allow `#[omit_gdb_pretty_printer_section]` |
| // rustc internal. |
| (active, omit_gdb_pretty_printer_section, "1.5.0", None), |
| |
| // Allows cfg(target_vendor = "..."). |
| (active, cfg_target_vendor, "1.5.0", Some(29718)), |
| |
| // Allow attributes on expressions and non-item statements |
| (active, stmt_expr_attributes, "1.6.0", Some(15701)), |
| |
| // allow using type ascription in expressions |
| (active, type_ascription, "1.6.0", Some(23416)), |
| |
| // Allows cfg(target_thread_local) |
| (active, cfg_target_thread_local, "1.7.0", Some(29594)), |
| |
| // rustc internal |
| (active, abi_vectorcall, "1.7.0", None), |
| |
| // a..=b and ..=b |
| (active, inclusive_range_syntax, "1.7.0", Some(28237)), |
| |
| // X..Y patterns |
| (active, exclusive_range_pattern, "1.11.0", Some(37854)), |
| |
| // impl specialization (RFC 1210) |
| (active, specialization, "1.7.0", Some(31844)), |
| |
| // Allows cfg(target_has_atomic = "..."). |
| (active, cfg_target_has_atomic, "1.9.0", Some(32976)), |
| |
| // Allows `impl Trait` in function return types. |
| (active, conservative_impl_trait, "1.12.0", Some(34511)), |
| |
| // Allows `impl Trait` in function arguments. |
| (active, universal_impl_trait, "1.23.0", Some(34511)), |
| |
| // The `!` type |
| (active, never_type, "1.13.0", Some(35121)), |
| |
| // Allows all literals in attribute lists and values of key-value pairs. |
| (active, attr_literals, "1.13.0", Some(34981)), |
| |
| // Allows the sysV64 ABI to be specified on all platforms |
| // instead of just the platforms on which it is the C ABI |
| (active, abi_sysv64, "1.13.0", Some(36167)), |
| |
| // Allows untagged unions `union U { ... }` |
| (active, untagged_unions, "1.13.0", Some(32836)), |
| |
| // Used to identify the `compiler_builtins` crate |
| // rustc internal |
| (active, compiler_builtins, "1.13.0", None), |
| |
| // Allows attributes on lifetime/type formal parameters in generics (RFC 1327) |
| (active, generic_param_attrs, "1.11.0", Some(34761)), |
| |
| // Allows #[link(..., cfg(..))] |
| (active, link_cfg, "1.14.0", Some(37406)), |
| |
| (active, use_extern_macros, "1.15.0", Some(35896)), |
| |
| // Allows #[target_feature(...)] |
| (active, target_feature, "1.15.0", None), |
| |
| // `extern "ptx-*" fn()` |
| (active, abi_ptx, "1.15.0", None), |
| |
| // The `i128` type |
| (active, i128_type, "1.16.0", Some(35118)), |
| |
| // The `repr(i128)` annotation for enums |
| (active, repr128, "1.16.0", Some(35118)), |
| |
| // The `unadjusted` ABI. Perma unstable. |
| (active, abi_unadjusted, "1.16.0", None), |
| |
| // Procedural macros 2.0. |
| (active, proc_macro, "1.16.0", Some(38356)), |
| |
| // Declarative macros 2.0 (`macro`). |
| (active, decl_macro, "1.17.0", Some(39412)), |
| |
| // Allows #[link(kind="static-nobundle"...] |
| (active, static_nobundle, "1.16.0", Some(37403)), |
| |
| // `extern "msp430-interrupt" fn()` |
| (active, abi_msp430_interrupt, "1.16.0", Some(38487)), |
| |
| // Used to identify crates that contain sanitizer runtimes |
| // rustc internal |
| (active, sanitizer_runtime, "1.17.0", None), |
| |
| // Used to identify crates that contain the profiler runtime |
| // rustc internal |
| (active, profiler_runtime, "1.18.0", None), |
| |
| // `extern "x86-interrupt" fn()` |
| (active, abi_x86_interrupt, "1.17.0", Some(40180)), |
| |
| |
| // Allows the `catch {...}` expression |
| (active, catch_expr, "1.17.0", Some(31436)), |
| |
| // Allows `repr(align(u16))` struct attribute (RFC 1358) |
| (active, repr_align, "1.17.0", Some(33626)), |
| |
| // Used to preserve symbols (see llvm.used) |
| (active, used, "1.18.0", Some(40289)), |
| |
| // Allows module-level inline assembly by way of global_asm!() |
| (active, global_asm, "1.18.0", Some(35119)), |
| |
| // Allows overlapping impls of marker traits |
| (active, overlapping_marker_traits, "1.18.0", Some(29864)), |
| |
| // Allows use of the :vis macro fragment specifier |
| (active, macro_vis_matcher, "1.18.0", Some(41022)), |
| |
| // rustc internal |
| (active, abi_thiscall, "1.19.0", None), |
| |
| // Allows a test to fail without failing the whole suite |
| (active, allow_fail, "1.19.0", Some(42219)), |
| |
| // Allows unsized tuple coercion. |
| (active, unsized_tuple_coercion, "1.20.0", Some(42877)), |
| |
| // Generators |
| (active, generators, "1.21.0", None), |
| |
| |
| // global allocators and their internals |
| (active, global_allocator, "1.20.0", None), |
| (active, allocator_internals, "1.20.0", None), |
| |
| // #[doc(cfg(...))] |
| (active, doc_cfg, "1.21.0", Some(43781)), |
| // #[doc(masked)] |
| (active, doc_masked, "1.21.0", Some(44027)), |
| |
| // allow `#[must_use]` on functions and comparison operators (RFC 1940) |
| (active, fn_must_use, "1.21.0", Some(43302)), |
| |
| // allow '|' at beginning of match arms (RFC 1925) |
| (active, match_beginning_vert, "1.21.0", Some(44101)), |
| |
| // Future-proofing enums/structs with #[non_exhaustive] attribute (RFC 2008) |
| (active, non_exhaustive, "1.22.0", Some(44109)), |
| |
| // Copy/Clone closures (RFC 2132) |
| (active, clone_closures, "1.22.0", Some(44490)), |
| (active, copy_closures, "1.22.0", Some(44490)), |
| |
| // allow `'_` placeholder lifetimes |
| (active, underscore_lifetimes, "1.22.0", Some(44524)), |
| |
| // allow `..=` in patterns (RFC 1192) |
| (active, dotdoteq_in_patterns, "1.22.0", Some(28237)), |
| |
| // Default match binding modes (RFC 2005) |
| (active, match_default_bindings, "1.22.0", Some(42640)), |
| |
| // Trait object syntax with `dyn` prefix |
| (active, dyn_trait, "1.22.0", Some(44662)), |
| |
| // `crate` as visibility modifier, synonymous to `pub(crate)` |
| (active, crate_visibility_modifier, "1.23.0", Some(45388)), |
| |
| // extern types |
| (active, extern_types, "1.23.0", Some(43467)), |
| |
| // Allow trait methods with arbitrary self types |
| (active, arbitrary_self_types, "1.23.0", Some(44874)), |
| |
| // #![wasm_import_memory] attribute |
| (active, wasm_import_memory, "1.22.0", None), |
| ); |
| |
| declare_features! ( |
| (removed, import_shadowing, "1.0.0", None), |
| (removed, managed_boxes, "1.0.0", None), |
| // Allows use of unary negate on unsigned integers, e.g. -e for e: u8 |
| (removed, negate_unsigned, "1.0.0", Some(29645)), |
| (removed, reflect, "1.0.0", Some(27749)), |
| // A way to temporarily opt out of opt in copy. This will *never* be accepted. |
| (removed, opt_out_copy, "1.0.0", None), |
| (removed, quad_precision_float, "1.0.0", None), |
| (removed, struct_inherit, "1.0.0", None), |
| (removed, test_removed_feature, "1.0.0", None), |
| (removed, visible_private_types, "1.0.0", None), |
| (removed, unsafe_no_drop_flag, "1.0.0", None), |
| // Allows using items which are missing stability attributes |
| // rustc internal |
| (removed, unmarked_api, "1.0.0", None), |
| (removed, pushpop_unsafe, "1.2.0", None), |
| (removed, allocator, "1.0.0", None), |
| ); |
| |
| declare_features! ( |
| (stable_removed, no_stack_check, "1.0.0", None), |
| ); |
| |
| declare_features! ( |
| (accepted, associated_types, "1.0.0", None), |
| // allow overloading augmented assignment operations like `a += b` |
| (accepted, augmented_assignments, "1.8.0", Some(28235)), |
| // allow empty structs and enum variants with braces |
| (accepted, braced_empty_structs, "1.8.0", Some(29720)), |
| (accepted, default_type_params, "1.0.0", None), |
| (accepted, globs, "1.0.0", None), |
| (accepted, if_let, "1.0.0", None), |
| // A temporary feature gate used to enable parser extensions needed |
| // to bootstrap fix for #5723. |
| (accepted, issue_5723_bootstrap, "1.0.0", None), |
| (accepted, macro_rules, "1.0.0", None), |
| // Allows using #![no_std] |
| (accepted, no_std, "1.6.0", None), |
| (accepted, slicing_syntax, "1.0.0", None), |
| (accepted, struct_variant, "1.0.0", 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), |
| (accepted, tuple_indexing, "1.0.0", None), |
| // Allows macros to appear in the type position. |
| (accepted, type_macros, "1.13.0", Some(27245)), |
| (accepted, while_let, "1.0.0", None), |
| // Allows `#[deprecated]` attribute |
| (accepted, deprecated, "1.9.0", Some(29935)), |
| // `expr?` |
| (accepted, question_mark, "1.13.0", Some(31436)), |
| // Allows `..` in tuple (struct) patterns |
| (accepted, dotdot_in_tuple_patterns, "1.14.0", Some(33627)), |
| (accepted, item_like_imports, "1.15.0", Some(35120)), |
| // Allows using `Self` and associated types in struct expressions and patterns. |
| (accepted, more_struct_aliases, "1.16.0", Some(37544)), |
| // elide `'static` lifetimes in `static`s and `const`s |
| (accepted, static_in_const, "1.17.0", Some(35897)), |
| // Allows field shorthands (`x` meaning `x: x`) in struct literal expressions. |
| (accepted, field_init_shorthand, "1.17.0", Some(37340)), |
| // Allows the definition recursive static items. |
| (accepted, static_recursion, "1.17.0", Some(29719)), |
| // pub(restricted) visibilities (RFC 1422) |
| (accepted, pub_restricted, "1.18.0", Some(32409)), |
| // The #![windows_subsystem] attribute |
| (accepted, windows_subsystem, "1.18.0", Some(37499)), |
| // Allows `break {expr}` with a value inside `loop`s. |
| (accepted, loop_break_value, "1.19.0", Some(37339)), |
| // Permits numeric fields in struct expressions and patterns. |
| (accepted, relaxed_adts, "1.19.0", Some(35626)), |
| // Coerces non capturing closures to function pointers |
| (accepted, closure_to_fn_coercion, "1.19.0", Some(39817)), |
| // Allows attributes on struct literal fields. |
| (accepted, struct_field_attributes, "1.20.0", Some(38814)), |
| // Allows the definition of associated constants in `trait` or `impl` |
| // blocks. |
| (accepted, associated_consts, "1.20.0", Some(29646)), |
| // Usage of the `compile_error!` macro |
| (accepted, compile_error, "1.20.0", Some(40872)), |
| // See rust-lang/rfcs#1414. Allows code like `let x: &'static u32 = &42` to work. |
| (accepted, rvalue_static_promotion, "1.21.0", Some(38865)), |
| // Allow Drop types in constants (RFC 1440) |
| (accepted, drop_types_in_const, "1.22.0", Some(33156)), |
| ); |
| |
| // 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(PartialEq, Copy, Clone, 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, &'static str, &'static str, fn(&Features) -> bool), |
| |
| /// Ungated attribute, can be used on all release channels |
| Ungated, |
| } |
| |
| impl AttributeGate { |
| fn is_deprecated(&self) -> bool { |
| match *self { |
| Gated(Stability::Deprecated(_), ..) => true, |
| _ => false, |
| } |
| } |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Eq, Debug)] |
| pub enum Stability { |
| Unstable, |
| // Argument is tracking issue link. |
| Deprecated(&'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 (&'static str, AttributeType, AttributeGate)> { |
| BUILTIN_ATTRIBUTES.iter().filter(|a| a.2.is_deprecated()).collect() |
| } |
| |
| pub fn is_builtin_attr(attr: &ast::Attribute) -> bool { |
| BUILTIN_ATTRIBUTES.iter().any(|&(builtin_name, _, _)| attr.check_name(builtin_name)) |
| } |
| |
| // Attributes that have a special meaning to rustc or rustdoc |
| pub const BUILTIN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeGate)] = &[ |
| // Normal attributes |
| |
| ("warn", Normal, Ungated), |
| ("allow", Normal, Ungated), |
| ("forbid", Normal, Ungated), |
| ("deny", Normal, Ungated), |
| |
| ("macro_reexport", Normal, Ungated), |
| ("macro_use", Normal, Ungated), |
| ("macro_export", Normal, Ungated), |
| ("plugin_registrar", Normal, Ungated), |
| |
| ("cfg", Normal, Ungated), |
| ("cfg_attr", Normal, Ungated), |
| ("main", Normal, Ungated), |
| ("start", Normal, Ungated), |
| ("test", Normal, Ungated), |
| ("bench", Normal, Ungated), |
| ("simd", Normal, Ungated), |
| ("repr", Normal, Ungated), |
| ("path", Normal, Ungated), |
| ("abi", Normal, Ungated), |
| ("automatically_derived", Normal, Ungated), |
| ("no_mangle", Normal, Ungated), |
| ("no_link", Normal, Ungated), |
| ("derive", Normal, Ungated), |
| ("should_panic", Normal, Ungated), |
| ("ignore", Normal, Ungated), |
| ("no_implicit_prelude", Normal, Ungated), |
| ("reexport_test_harness_main", Normal, Ungated), |
| ("link_args", Normal, Gated(Stability::Unstable, |
| "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))), |
| ("macro_escape", Normal, Ungated), |
| |
| // RFC #1445. |
| ("structural_match", Whitelisted, Gated(Stability::Unstable, |
| "structural_match", |
| "the semantics of constant patterns is \ |
| not yet settled", |
| cfg_fn!(structural_match))), |
| |
| // RFC #2008 |
| ("non_exhaustive", Whitelisted, Gated(Stability::Unstable, |
| "non_exhaustive", |
| "non exhaustive is an experimental feature", |
| cfg_fn!(non_exhaustive))), |
| |
| ("plugin", CrateLevel, Gated(Stability::Unstable, |
| "plugin", |
| "compiler plugins are experimental \ |
| and possibly buggy", |
| cfg_fn!(plugin))), |
| |
| ("no_std", CrateLevel, Ungated), |
| ("no_core", CrateLevel, Gated(Stability::Unstable, |
| "no_core", |
| "no_core is experimental", |
| cfg_fn!(no_core))), |
| ("lang", Normal, Gated(Stability::Unstable, |
| "lang_items", |
| "language items are subject to change", |
| cfg_fn!(lang_items))), |
| ("linkage", Whitelisted, Gated(Stability::Unstable, |
| "linkage", |
| "the `linkage` attribute is experimental \ |
| and not portable across platforms", |
| cfg_fn!(linkage))), |
| ("thread_local", Whitelisted, Gated(Stability::Unstable, |
| "thread_local", |
| "`#[thread_local]` is an experimental feature, and does \ |
| not currently handle destructors. There is no \ |
| corresponding `#[task_local]` mapping to the task \ |
| model", |
| cfg_fn!(thread_local))), |
| |
| ("rustc_on_unimplemented", Normal, Gated(Stability::Unstable, |
| "on_unimplemented", |
| "the `#[rustc_on_unimplemented]` attribute \ |
| is an experimental feature", |
| cfg_fn!(on_unimplemented))), |
| ("rustc_const_unstable", Normal, Gated(Stability::Unstable, |
| "rustc_const_unstable", |
| "the `#[rustc_const_unstable]` attribute \ |
| is an internal feature", |
| cfg_fn!(rustc_const_unstable))), |
| ("global_allocator", Normal, Gated(Stability::Unstable, |
| "global_allocator", |
| "the `#[global_allocator]` attribute is \ |
| an experimental feature", |
| cfg_fn!(global_allocator))), |
| ("default_lib_allocator", Whitelisted, Gated(Stability::Unstable, |
| "allocator_internals", |
| "the `#[default_lib_allocator]` \ |
| attribute is an experimental feature", |
| cfg_fn!(allocator_internals))), |
| ("needs_allocator", Normal, Gated(Stability::Unstable, |
| "allocator_internals", |
| "the `#[needs_allocator]` \ |
| attribute is an experimental \ |
| feature", |
| cfg_fn!(allocator_internals))), |
| ("panic_runtime", Whitelisted, Gated(Stability::Unstable, |
| "panic_runtime", |
| "the `#[panic_runtime]` attribute is \ |
| an experimental feature", |
| cfg_fn!(panic_runtime))), |
| ("needs_panic_runtime", Whitelisted, Gated(Stability::Unstable, |
| "needs_panic_runtime", |
| "the `#[needs_panic_runtime]` \ |
| attribute is an experimental \ |
| feature", |
| cfg_fn!(needs_panic_runtime))), |
| ("rustc_variance", Normal, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "the `#[rustc_variance]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_error", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "the `#[rustc_error]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_if_this_changed", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "the `#[rustc_if_this_changed]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_then_this_would_need", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "the `#[rustc_if_this_changed]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_dirty", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "the `#[rustc_dirty]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_clean", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "the `#[rustc_clean]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_metadata_dirty", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "the `#[rustc_metadata_dirty]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_metadata_clean", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "the `#[rustc_metadata_clean]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_partition_reused", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "this attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_partition_translated", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "this attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_synthetic", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "this attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_symbol_name", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "internal rustc attributes will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_item_path", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "internal rustc attributes will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_mir", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "the `#[rustc_mir]` attribute \ |
| is just used for rustc unit tests \ |
| and will never be stable", |
| cfg_fn!(rustc_attrs))), |
| ("rustc_inherit_overflow_checks", Whitelisted, Gated(Stability::Unstable, |
| "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))), |
| ("compiler_builtins", Whitelisted, Gated(Stability::Unstable, |
| "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))), |
| ("sanitizer_runtime", Whitelisted, Gated(Stability::Unstable, |
| "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))), |
| ("profiler_runtime", Whitelisted, Gated(Stability::Unstable, |
| "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))), |
| |
| ("allow_internal_unstable", Normal, Gated(Stability::Unstable, |
| "allow_internal_unstable", |
| EXPLAIN_ALLOW_INTERNAL_UNSTABLE, |
| cfg_fn!(allow_internal_unstable))), |
| |
| ("allow_internal_unsafe", Normal, Gated(Stability::Unstable, |
| "allow_internal_unsafe", |
| EXPLAIN_ALLOW_INTERNAL_UNSAFE, |
| cfg_fn!(allow_internal_unsafe))), |
| |
| ("fundamental", Whitelisted, Gated(Stability::Unstable, |
| "fundamental", |
| "the `#[fundamental]` attribute \ |
| is an experimental feature", |
| cfg_fn!(fundamental))), |
| |
| ("proc_macro_derive", Normal, Ungated), |
| |
| ("rustc_copy_clone_marker", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "internal implementation detail", |
| cfg_fn!(rustc_attrs))), |
| |
| // FIXME: #14408 whitelist docs since rustdoc looks at them |
| ("doc", Whitelisted, Ungated), |
| |
| // FIXME: #14406 these are processed in trans, which happens after the |
| // lint pass |
| ("cold", Whitelisted, Ungated), |
| ("naked", Whitelisted, Gated(Stability::Unstable, |
| "naked_functions", |
| "the `#[naked]` attribute \ |
| is an experimental feature", |
| cfg_fn!(naked_functions))), |
| ("target_feature", Whitelisted, Gated( |
| Stability::Unstable, "target_feature", |
| "the `#[target_feature]` attribute is an experimental feature", |
| cfg_fn!(target_feature))), |
| ("export_name", Whitelisted, Ungated), |
| ("inline", Whitelisted, Ungated), |
| ("link", Whitelisted, Ungated), |
| ("link_name", Whitelisted, Ungated), |
| ("link_section", Whitelisted, Ungated), |
| ("no_builtins", Whitelisted, Ungated), |
| ("no_mangle", Whitelisted, Ungated), |
| ("no_debug", Whitelisted, Gated( |
| Stability::Deprecated("https://github.com/rust-lang/rust/issues/29721"), |
| "no_debug", |
| "the `#[no_debug]` attribute was an experimental feature that has been \ |
| deprecated due to lack of demand", |
| cfg_fn!(no_debug))), |
| ("omit_gdb_pretty_printer_section", Whitelisted, Gated(Stability::Unstable, |
| "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))), |
| ("unsafe_destructor_blind_to_params", |
| Normal, |
| Gated(Stability::Deprecated("https://github.com/rust-lang/rust/issues/34761"), |
| "dropck_parametricity", |
| "unsafe_destructor_blind_to_params has been replaced by \ |
| may_dangle and will be removed in the future", |
| cfg_fn!(dropck_parametricity))), |
| ("may_dangle", |
| Normal, |
| Gated(Stability::Unstable, |
| "dropck_eyepatch", |
| "may_dangle has unstable semantics and may be removed in the future", |
| cfg_fn!(dropck_eyepatch))), |
| ("unwind", Whitelisted, Gated(Stability::Unstable, |
| "unwind_attributes", |
| "#[unwind] is experimental", |
| cfg_fn!(unwind_attributes))), |
| ("used", Whitelisted, Gated( |
| Stability::Unstable, "used", |
| "the `#[used]` attribute is an experimental feature", |
| cfg_fn!(used))), |
| |
| // used in resolve |
| ("prelude_import", Whitelisted, Gated(Stability::Unstable, |
| "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 |
| ("rustc_deprecated", Whitelisted, Ungated), |
| ("must_use", Whitelisted, Ungated), |
| ("stable", Whitelisted, Ungated), |
| ("unstable", Whitelisted, Ungated), |
| ("deprecated", Normal, Ungated), |
| |
| ("rustc_paren_sugar", Normal, Gated(Stability::Unstable, |
| "unboxed_closures", |
| "unboxed_closures are still evolving", |
| cfg_fn!(unboxed_closures))), |
| |
| ("windows_subsystem", Whitelisted, Ungated), |
| |
| ("proc_macro_attribute", Normal, Gated(Stability::Unstable, |
| "proc_macro", |
| "attribute proc macros are currently unstable", |
| cfg_fn!(proc_macro))), |
| |
| ("proc_macro", Normal, Gated(Stability::Unstable, |
| "proc_macro", |
| "function-like proc macros are currently unstable", |
| cfg_fn!(proc_macro))), |
| |
| ("rustc_derive_registrar", Normal, Gated(Stability::Unstable, |
| "rustc_derive_registrar", |
| "used internally by rustc", |
| cfg_fn!(rustc_attrs))), |
| |
| ("allow_fail", Normal, Gated(Stability::Unstable, |
| "allow_fail", |
| "allow_fail attribute is currently unstable", |
| cfg_fn!(allow_fail))), |
| |
| ("rustc_std_internal_symbol", Whitelisted, Gated(Stability::Unstable, |
| "rustc_attrs", |
| "this is an internal attribute that will \ |
| never be stable", |
| cfg_fn!(rustc_attrs))), |
| |
| ("wasm_import_memory", Whitelisted, Gated(Stability::Unstable, |
| "wasm_import_memory", |
| "wasm_import_memory attribute is currently unstable", |
| cfg_fn!(wasm_import_memory))), |
| |
| // Crate level attributes |
| ("crate_name", CrateLevel, Ungated), |
| ("crate_type", CrateLevel, Ungated), |
| ("crate_id", CrateLevel, Ungated), |
| ("feature", CrateLevel, Ungated), |
| ("no_start", CrateLevel, Ungated), |
| ("no_main", CrateLevel, Ungated), |
| ("no_builtins", CrateLevel, Ungated), |
| ("recursion_limit", CrateLevel, Ungated), |
| ("type_length_limit", CrateLevel, Ungated), |
| ]; |
| |
| // cfg(...)'s that are feature gated |
| const GATED_CFGS: &[(&str, &str, fn(&Features) -> bool)] = &[ |
| // (name in cfg, feature, function to check if the feature is enabled) |
| ("target_feature", "cfg_target_feature", cfg_fn!(cfg_target_feature)), |
| ("target_vendor", "cfg_target_vendor", cfg_fn!(cfg_target_vendor)), |
| ("target_thread_local", "cfg_target_thread_local", cfg_fn!(cfg_target_thread_local)), |
| ("target_has_atomic", "cfg_target_has_atomic", cfg_fn!(cfg_target_has_atomic)), |
| ]; |
| |
| #[derive(Debug, Eq, PartialEq)] |
| pub struct GatedCfg { |
| span: Span, |
| index: usize, |
| } |
| |
| impl GatedCfg { |
| pub fn gate(cfg: &ast::MetaItem) -> Option<GatedCfg> { |
| let name = cfg.name().as_str(); |
| GATED_CFGS.iter() |
| .position(|info| info.0 == name) |
| .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() { |
| 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 [(String, 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() { |
| 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, $span, |
| stringify!($feature), $explain, GateStrength::Hard) |
| }; |
| ($cx: expr, $feature: ident, $span: expr, $explain: expr, $level: expr) => { |
| gate_feature_fn!($cx, |x:&Features| x.$feature, $span, |
| stringify!($feature), $explain, $level) |
| }; |
| } |
| |
| impl<'a> Context<'a> { |
| fn check_attribute(&self, attr: &ast::Attribute, is_macro: bool) { |
| debug!("check_attribute(attr = {:?})", attr); |
| let name = unwrap_or!(attr.name(), return).as_str(); |
| for &(n, ty, ref gateage) in BUILTIN_ATTRIBUTES { |
| if name == n { |
| if let Gated(_, name, desc, ref has_feature) = *gateage { |
| gate_feature_fn!(self, has_feature, attr.span, name, desc, GateStrength::Hard); |
| } |
| debug!("check_attribute: {:?} is builtin, {:?}, {:?}", attr.path, ty, gateage); |
| return; |
| } |
| } |
| for &(ref n, ref 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 name.starts_with("rustc_") { |
| gate_feature!(self, rustc_attrs, attr.span, |
| "unless otherwise specified, attributes \ |
| with the prefix `rustc_` \ |
| are reserved for internal compiler diagnostics"); |
| } else if name.starts_with("derive_") { |
| gate_feature!(self, custom_derive, attr.span, EXPLAIN_DERIVE_UNDERSCORE); |
| } else if !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 then |
| if !is_macro { |
| gate_feature!(self, custom_attribute, attr.span, |
| &format!("The attribute `{}` is currently \ |
| unknown to the compiler and \ |
| may have meaning \ |
| added to it in the future", |
| attr.path)); |
| } |
| } |
| } |
| } |
| |
| pub fn check_attribute(attr: &ast::Attribute, parse_sess: &ParseSess, features: &Features) { |
| let cx = Context { features: features, parse_sess: parse_sess, plugin_attributes: &[] }; |
| cx.check_attribute(attr, true); |
| } |
| |
| pub fn find_lang_feature_accepted_version(feature: &str) -> Option<&'static str> { |
| ACCEPTED_FEATURES.iter().find(|t| t.0 == feature).map(|t| t.1) |
| } |
| |
| fn find_lang_feature_issue(feature: &str) -> 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, Eq)] |
| 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: &str, span: Span, issue: GateIssue, |
| explain: &str) { |
| feature_err(sess, feature, span, issue, explain).emit(); |
| } |
| |
| pub fn feature_err<'a>(sess: &'a ParseSess, feature: &str, span: Span, issue: GateIssue, |
| explain: &str) -> DiagnosticBuilder<'a> { |
| leveled_feature_err(sess, feature, span, issue, explain, GateStrength::Hard) |
| } |
| |
| fn leveled_feature_err<'a>(sess: &'a ParseSess, feature: &str, span: Span, 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 explanation = if let Some(n) = issue { |
| format!("{} (see issue #{})", explain, n) |
| } else { |
| explain.to_owned() |
| }; |
| |
| let mut err = match level { |
| GateStrength::Hard => diag.struct_span_err(span, &explanation), |
| GateStrength::Soft => diag.struct_span_warn(span, &explanation), |
| }; |
| |
| // #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: &'static str = |
| "box expression syntax is experimental; you can call `Box::new` instead."; |
| |
| pub const EXPLAIN_STMT_ATTR_SYNTAX: &'static str = |
| "attributes on non-item statements and expressions are experimental."; |
| |
| pub const EXPLAIN_ASM: &'static str = |
| "inline assembly is not stable enough for use and is subject to change"; |
| |
| pub const EXPLAIN_GLOBAL_ASM: &'static str = |
| "`global_asm!` is not stable enough for use and is subject to change"; |
| |
| pub const EXPLAIN_LOG_SYNTAX: &'static str = |
| "`log_syntax!` is not stable enough for use and is subject to change"; |
| |
| pub const EXPLAIN_CONCAT_IDENTS: &'static str = |
| "`concat_idents` is not stable enough for use and is subject to change"; |
| |
| pub const EXPLAIN_TRACE_MACROS: &'static str = |
| "`trace_macros` is not stable enough for use and is subject to change"; |
| pub const EXPLAIN_ALLOW_INTERNAL_UNSTABLE: &'static str = |
| "allow_internal_unstable side-steps feature gating and stability checks"; |
| pub const EXPLAIN_ALLOW_INTERNAL_UNSAFE: &'static str = |
| "allow_internal_unsafe side-steps the unsafe_code lint"; |
| |
| pub const EXPLAIN_CUSTOM_DERIVE: &'static str = |
| "`#[derive]` for custom traits is deprecated and will be removed in the future."; |
| |
| pub const EXPLAIN_DEPR_CUSTOM_DERIVE: &'static str = |
| "`#[derive]` for custom traits is deprecated and will be removed in the future. \ |
| Prefer using procedural macro custom derive."; |
| |
| pub const EXPLAIN_DERIVE_UNDERSCORE: &'static str = |
| "attributes of the form `#[derive_*]` are reserved for the compiler"; |
| |
| pub const EXPLAIN_VIS_MATCHER: &'static str = |
| ":vis fragment specifier is experimental and subject to change"; |
| |
| pub const EXPLAIN_PLACEMENT_IN: &'static str = |
| "placement-in expression syntax is experimental and subject to change."; |
| |
| pub const EXPLAIN_UNSIZED_TUPLE_COERCION: &'static str = |
| "Unsized tuple coercion is not stable enough for use and is subject to change"; |
| |
| struct PostExpansionVisitor<'a> { |
| context: &'a Context<'a>, |
| } |
| |
| macro_rules! gate_feature_post { |
| ($cx: expr, $feature: ident, $span: expr, $explain: expr) => {{ |
| let (cx, span) = ($cx, $span); |
| if !span.allows_unstable() { |
| 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() { |
| 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::SysV64 => { |
| gate_feature_post!(&self, abi_sysv64, span, |
| "sysv64 ABI is experimental and 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"); |
| }, |
| // Stable |
| Abi::Cdecl | |
| Abi::Stdcall | |
| Abi::Fastcall | |
| Abi::Aapcs | |
| Abi::Win64 | |
| Abi::Rust | |
| Abi::C | |
| Abi::System => {} |
| } |
| } |
| } |
| |
| fn contains_novel_literal(item: &ast::MetaItem) -> bool { |
| use ast::MetaItemKind::*; |
| use ast::NestedMetaItemKind::*; |
| |
| match item.node { |
| Word => false, |
| NameValue(ref lit) => !lit.node.is_str(), |
| List(ref list) => list.iter().any(|li| { |
| match li.node { |
| MetaItem(ref mi) => contains_novel_literal(mi), |
| Literal(_) => true, |
| } |
| }), |
| } |
| } |
| |
| impl<'a> Visitor<'a> for PostExpansionVisitor<'a> { |
| fn visit_attribute(&mut self, attr: &ast::Attribute) { |
| if !attr.span.allows_unstable() { |
| // check for gated attributes |
| self.context.check_attribute(attr, false); |
| } |
| |
| if attr.check_name("doc") { |
| if let Some(content) = attr.meta_item_list() { |
| if content.len() == 1 && content[0].check_name("cfg") { |
| gate_feature_post!(&self, doc_cfg, attr.span, |
| "#[doc(cfg(...))] is experimental" |
| ); |
| } else if content.iter().any(|c| c.check_name("masked")) { |
| gate_feature_post!(&self, doc_masked, attr.span, |
| "#[doc(masked)] is experimental" |
| ); |
| } |
| } |
| } |
| |
| if self.context.features.proc_macro && attr::is_known(attr) { |
| return |
| } |
| |
| let meta = panictry!(attr.parse_meta(self.context.parse_sess)); |
| if contains_novel_literal(&meta) { |
| gate_feature_post!(&self, attr_literals, attr.span, |
| "non-string literals in attributes, or string \ |
| literals in top-level positions, are experimental"); |
| } |
| } |
| |
| fn visit_name(&mut self, sp: Span, name: ast::Name) { |
| if !name.as_str().is_ascii() { |
| gate_feature_post!(&self, non_ascii_idents, sp, |
| "non-ascii idents are not fully supported."); |
| } |
| } |
| |
| fn visit_item(&mut self, i: &'a ast::Item) { |
| match i.node { |
| ast::ItemKind::ExternCrate(_) => { |
| if let Some(attr) = attr::find_by_name(&i.attrs[..], "macro_reexport") { |
| gate_feature_post!(&self, macro_reexport, attr.span, |
| "macros reexports are experimental \ |
| and possibly buggy"); |
| } |
| } |
| |
| ast::ItemKind::ForeignMod(ref foreign_module) => { |
| self.check_abi(foreign_module.abi, i.span); |
| } |
| |
| ast::ItemKind::Fn(..) => { |
| if attr::contains_name(&i.attrs[..], "plugin_registrar") { |
| gate_feature_post!(&self, plugin_registrar, i.span, |
| "compiler plugins are experimental and possibly buggy"); |
| } |
| if attr::contains_name(&i.attrs[..], "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[..], "main") { |
| gate_feature_post!(&self, main, i.span, |
| "declaration of a nonstandard #[main] \ |
| function may change over time, for now \ |
| a top-level `fn main()` is required"); |
| } |
| if let Some(attr) = attr::find_by_name(&i.attrs[..], "must_use") { |
| gate_feature_post!(&self, fn_must_use, attr.span, |
| "`#[must_use]` on functions is experimental", |
| GateStrength::Soft); |
| } |
| } |
| |
| ast::ItemKind::Struct(..) => { |
| if let Some(attr) = attr::find_by_name(&i.attrs[..], "simd") { |
| gate_feature_post!(&self, simd, attr.span, |
| "SIMD types are experimental and possibly buggy"); |
| self.context.parse_sess.span_diagnostic.span_warn(attr.span, |
| "the `#[simd]` attribute \ |
| is deprecated, use \ |
| `#[repr(simd)]` instead"); |
| } |
| if let Some(attr) = attr::find_by_name(&i.attrs[..], "repr") { |
| for item in attr.meta_item_list().unwrap_or_else(Vec::new) { |
| if item.check_name("simd") { |
| gate_feature_post!(&self, repr_simd, attr.span, |
| "SIMD types are experimental and possibly buggy"); |
| } |
| if item.check_name("align") { |
| gate_feature_post!(&self, repr_align, attr.span, |
| "the struct `#[repr(align(u16))]` attribute \ |
| is experimental"); |
| } |
| } |
| } |
| } |
| |
| ast::ItemKind::AutoImpl(..) => { |
| gate_feature_post!(&self, optin_builtin_traits, |
| i.span, |
| "auto trait implementations are experimental \ |
| and possibly buggy"); |
| } |
| |
| ast::ItemKind::Impl(_, polarity, defaultness, _, _, _, ref impl_items) => { |
| 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"); |
| } |
| |
| for impl_item in impl_items { |
| if let ast::ImplItemKind::Method(..) = impl_item.node { |
| if let Some(attr) = attr::find_by_name(&impl_item.attrs[..], "must_use") { |
| gate_feature_post!(&self, fn_must_use, attr.span, |
| "`#[must_use]` on methods is experimental", |
| GateStrength::Soft); |
| } |
| } |
| } |
| } |
| |
| ast::ItemKind::Trait(ast::IsAuto::Yes, ..) => { |
| gate_feature_post!(&self, optin_builtin_traits, |
| i.span, |
| "auto traits are experimental and possibly buggy"); |
| } |
| |
| ast::ItemKind::MacroDef(ast::MacroDef { legacy: false, .. }) => { |
| let msg = "`macro` is experimental"; |
| gate_feature_post!(&self, decl_macro, i.span, msg); |
| } |
| |
| _ => {} |
| } |
| |
| 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, "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"); |
| } |
| } |
| |
| 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"); |
| }, |
| ast::TyKind::TraitObject(_, ast::TraitObjectSyntax::Dyn) => { |
| gate_feature_post!(&self, dyn_trait, ty.span, |
| "`dyn Trait` syntax is unstable"); |
| } |
| _ => {} |
| } |
| 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 output_ty.node != ast::TyKind::Never { |
| 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(..) => { |
| gate_feature_post!(&self, type_ascription, e.span, |
| "type ascription is experimental"); |
| } |
| ast::ExprKind::Range(_, _, ast::RangeLimits::Closed) => { |
| gate_feature_post!(&self, inclusive_range_syntax, |
| e.span, |
| "inclusive range syntax is experimental"); |
| } |
| ast::ExprKind::InPlace(..) => { |
| gate_feature_post!(&self, placement_in_syntax, e.span, EXPLAIN_PLACEMENT_IN); |
| } |
| ast::ExprKind::Yield(..) => { |
| gate_feature_post!(&self, generators, |
| e.span, |
| "yield syntax is experimental"); |
| } |
| ast::ExprKind::Lit(ref lit) => { |
| if let ast::LitKind::Int(_, ref ty) = lit.node { |
| match *ty { |
| ast::LitIntType::Signed(ast::IntTy::I128) | |
| ast::LitIntType::Unsigned(ast::UintTy::U128) => { |
| gate_feature_post!(&self, i128_type, e.span, |
| "128-bit integers are not stable"); |
| } |
| _ => {} |
| } |
| } |
| } |
| ast::ExprKind::Catch(_) => { |
| gate_feature_post!(&self, catch_expr, e.span, "`catch` expression is experimental"); |
| } |
| _ => {} |
| } |
| visit::walk_expr(self, e); |
| } |
| |
| fn visit_arm(&mut self, arm: &'a ast::Arm) { |
| if let Some(span) = arm.beginning_vert { |
| gate_feature_post!(&self, match_beginning_vert, |
| span, |
| "Use of a '|' at the beginning of a match arm is experimental") |
| } |
| visit::walk_arm(self, arm) |
| } |
| |
| fn visit_pat(&mut self, pattern: &'a ast::Pat) { |
| match pattern.node { |
| PatKind::Slice(_, Some(_), ref last) if !last.is_empty() => { |
| gate_feature_post!(&self, advanced_slice_patterns, |
| pattern.span, |
| "multiple-element slice matches anywhere \ |
| but at the end of a slice (e.g. \ |
| `[0, ..xs, 0]`) are experimental") |
| } |
| PatKind::Slice(..) => { |
| gate_feature_post!(&self, slice_patterns, |
| pattern.span, |
| "slice pattern syntax is experimental"); |
| } |
| PatKind::Box(..) => { |
| gate_feature_post!(&self, box_patterns, |
| pattern.span, |
| "box pattern syntax is experimental"); |
| } |
| PatKind::Range(_, _, RangeEnd::Excluded) => { |
| gate_feature_post!(&self, exclusive_range_pattern, pattern.span, |
| "exclusive range pattern syntax is experimental"); |
| } |
| PatKind::Range(_, _, RangeEnd::Included(RangeSyntax::DotDotEq)) => { |
| gate_feature_post!(&self, dotdoteq_in_patterns, pattern.span, |
| "`..=` syntax in patterns 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) { |
| // check for const fn declarations |
| if let FnKind::ItemFn(_, _, Spanned { node: ast::Constness::Const, .. }, _, _, _) = |
| fn_kind { |
| gate_feature_post!(&self, const_fn, span, "const 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. |
| |
| match fn_kind { |
| FnKind::ItemFn(_, _, _, abi, _, _) | |
| FnKind::Method(_, &ast::MethodSig { abi, .. }, _, _) => { |
| self.check_abi(abi, span); |
| } |
| _ => {} |
| } |
| visit::walk_fn(self, fn_kind, fn_decl, span); |
| } |
| |
| 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.abi, ti.span); |
| } |
| if sig.constness.node == ast::Constness::Const { |
| gate_feature_post!(&self, const_fn, ti.span, "const fn is unstable"); |
| } |
| } |
| ast::TraitItemKind::Type(_, Some(_)) => { |
| gate_feature_post!(&self, associated_type_defaults, ti.span, |
| "associated type defaults 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(ref sig, _) => { |
| if sig.constness.node == ast::Constness::Const { |
| gate_feature_post!(&self, const_fn, ii.span, "const fn is unstable"); |
| } |
| } |
| _ => {} |
| } |
| visit::walk_impl_item(self, ii); |
| } |
| |
| fn visit_vis(&mut self, vis: &'a ast::Visibility) { |
| if let ast::Visibility::Crate(span, ast::CrateSugar::JustCrate) = *vis { |
| gate_feature_post!(&self, crate_visibility_modifier, span, |
| "`crate` visibility modifier is experimental"); |
| } |
| visit::walk_vis(self, vis); |
| } |
| |
| fn visit_generics(&mut self, g: &'a ast::Generics) { |
| for t in &g.ty_params { |
| if !t.attrs.is_empty() { |
| gate_feature_post!(&self, generic_param_attrs, t.attrs[0].span, |
| "attributes on type parameter bindings are experimental"); |
| } |
| } |
| visit::walk_generics(self, g) |
| } |
| |
| fn visit_lifetime_def(&mut self, lifetime_def: &'a ast::LifetimeDef) { |
| if !lifetime_def.attrs.is_empty() { |
| gate_feature_post!(&self, generic_param_attrs, lifetime_def.attrs[0].span, |
| "attributes on lifetime bindings are experimental"); |
| } |
| visit::walk_lifetime_def(self, lifetime_def) |
| } |
| |
| fn visit_lifetime(&mut self, lt: &'a ast::Lifetime) { |
| if lt.ident.name == "'_" { |
| gate_feature_post!(&self, underscore_lifetimes, lt.span, |
| "underscore lifetimes are unstable"); |
| } |
| visit::walk_lifetime(self, lt) |
| } |
| } |
| |
| pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute]) -> Features { |
| let mut features = Features::new(); |
| |
| let mut feature_checker = FeatureChecker::default(); |
| |
| for attr in krate_attrs { |
| if !attr.check_name("feature") { |
| continue |
| } |
| |
| match attr.meta_item_list() { |
| None => { |
| span_err!(span_handler, attr.span, E0555, |
| "malformed feature attribute, expected #![feature(...)]"); |
| } |
| Some(list) => { |
| for mi in list { |
| let name = if let Some(word) = mi.word() { |
| word.name() |
| } else { |
| span_err!(span_handler, mi.span, E0556, |
| "malformed feature, expected just one word"); |
| continue |
| }; |
| |
| if let Some(&(_, _, _, set)) = ACTIVE_FEATURES.iter() |
| .find(|& &(n, _, _, _)| name == n) { |
| set(&mut features, mi.span); |
| feature_checker.collect(&features, mi.span); |
| } |
| else if let Some(&(_, _, _)) = REMOVED_FEATURES.iter() |
| .find(|& &(n, _, _)| name == n) |
| .or_else(|| STABLE_REMOVED_FEATURES.iter() |
| .find(|& &(n, _, _)| name == n)) { |
| span_err!(span_handler, mi.span, E0557, "feature has been removed"); |
| } |
| else if let Some(&(_, _, _)) = ACCEPTED_FEATURES.iter() |
| .find(|& &(n, _, _)| name == n) { |
| features.declared_stable_lang_features.push((name, mi.span)); |
| } else { |
| features.declared_lib_features.push((name, mi.span)); |
| } |
| } |
| } |
| } |
| } |
| |
| feature_checker.check(span_handler); |
| |
| features |
| } |
| |
| /// A collector for mutually exclusive and interdependent features and their flag spans. |
| #[derive(Default)] |
| struct FeatureChecker { |
| proc_macro: Option<Span>, |
| custom_attribute: Option<Span>, |
| copy_closures: Option<Span>, |
| clone_closures: Option<Span>, |
| } |
| |
| impl FeatureChecker { |
| // If this method turns out to be a hotspot due to branching, |
| // the branching can be eliminated by modifying `set!()` to set these spans |
| // only for the features that need to be checked for mutual exclusion. |
| fn collect(&mut self, features: &Features, span: Span) { |
| if features.proc_macro { |
| // If self.proc_macro is None, set to Some(span) |
| self.proc_macro = self.proc_macro.or(Some(span)); |
| } |
| |
| if features.custom_attribute { |
| self.custom_attribute = self.custom_attribute.or(Some(span)); |
| } |
| |
| if features.copy_closures { |
| self.copy_closures = self.copy_closures.or(Some(span)); |
| } |
| |
| if features.clone_closures { |
| self.clone_closures = self.clone_closures.or(Some(span)); |
| } |
| } |
| |
| fn check(self, handler: &Handler) { |
| if let (Some(pm_span), Some(ca_span)) = (self.proc_macro, self.custom_attribute) { |
| handler.struct_span_err(pm_span, "Cannot use `#![feature(proc_macro)]` and \ |
| `#![feature(custom_attribute)] at the same time") |
| .span_note(ca_span, "`#![feature(custom_attribute)]` declared here") |
| .emit(); |
| |
| panic!(FatalError); |
| } |
| |
| if let (Some(span), None) = (self.copy_closures, self.clone_closures) { |
| handler.struct_span_err(span, "`#![feature(copy_closures)]` can only be used with \ |
| `#![feature(clone_closures)]`") |
| .span_note(span, "`#![feature(copy_closures)]` declared here") |
| .emit(); |
| |
| panic!(FatalError); |
| } |
| } |
| } |
| |
| pub fn check_crate(krate: &ast::Crate, |
| sess: &ParseSess, |
| features: &Features, |
| plugin_attributes: &[(String, AttributeType)], |
| unstable: UnstableFeatures) { |
| maybe_stage_features(&sess.span_diagnostic, krate, unstable); |
| let ctx = Context { |
| features, |
| parse_sess: sess, |
| plugin_attributes, |
| }; |
| visit::walk_crate(&mut PostExpansionVisitor { context: &ctx }, krate); |
| } |
| |
| #[derive(Clone, Copy, PartialEq, Eq, 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("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); |
| } |
| } |
| } |
| } |
