1289 lines
50 KiB
Rust
1289 lines
50 KiB
Rust
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Feature gating
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//!
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//! This module implements the gating necessary for preventing certain compiler
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//! features from being used by default. This module will crawl a pre-expanded
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//! AST to ensure that there are no features which are used that are not
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//! enabled.
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//!
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//! Features are enabled in programs via the crate-level attributes of
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//! `#![feature(...)]` with a comma-separated list of features.
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//!
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//! For the purpose of future feature-tracking, once code for detection of feature
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//! gate usage is added, *do not remove it again* even once the feature
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//! becomes stable.
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use self::Status::*;
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use self::AttributeType::*;
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use self::AttributeGate::*;
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use abi::Abi;
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use ast::{NodeId, PatKind};
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use ast;
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use attr;
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use attr::AttrMetaMethods;
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use codemap::{CodeMap, Span};
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use errors::Handler;
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use visit;
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use visit::{FnKind, Visitor};
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use parse::token::InternedString;
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use std::ascii::AsciiExt;
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use std::cmp;
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// If you change this list without updating src/doc/reference.md, @cmr will be sad
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// Don't ever remove anything from this list; set them to 'Removed'.
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// The version numbers here correspond to the version in which the current status
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// was set. This is most important for knowing when a particular feature became
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// stable (active).
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// NB: The featureck.py script parses this information directly out of the source
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// so take care when modifying it.
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const KNOWN_FEATURES: &'static [(&'static str, &'static str, Option<u32>, Status)] = &[
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("globs", "1.0.0", None, Accepted),
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("macro_rules", "1.0.0", None, Accepted),
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("struct_variant", "1.0.0", None, Accepted),
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("asm", "1.0.0", Some(29722), Active),
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("managed_boxes", "1.0.0", None, Removed),
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("non_ascii_idents", "1.0.0", Some(28979), Active),
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("thread_local", "1.0.0", Some(29594), Active),
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("link_args", "1.0.0", Some(29596), Active),
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("plugin_registrar", "1.0.0", Some(29597), Active),
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("log_syntax", "1.0.0", Some(29598), Active),
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("trace_macros", "1.0.0", Some(29598), Active),
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("concat_idents", "1.0.0", Some(29599), Active),
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// rustc internal, for now:
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("intrinsics", "1.0.0", None, Active),
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("lang_items", "1.0.0", None, Active),
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("simd", "1.0.0", Some(27731), Active),
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("default_type_params", "1.0.0", None, Accepted),
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("quote", "1.0.0", Some(29601), Active),
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("link_llvm_intrinsics", "1.0.0", Some(29602), Active),
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("linkage", "1.0.0", Some(29603), Active),
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("struct_inherit", "1.0.0", None, Removed),
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("quad_precision_float", "1.0.0", None, Removed),
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// rustc internal
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("rustc_diagnostic_macros", "1.0.0", None, Active),
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("unboxed_closures", "1.0.0", Some(29625), Active),
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("reflect", "1.0.0", Some(27749), Active),
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("import_shadowing", "1.0.0", None, Removed),
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("advanced_slice_patterns", "1.0.0", Some(23121), Active),
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("tuple_indexing", "1.0.0", None, Accepted),
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("associated_types", "1.0.0", None, Accepted),
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("visible_private_types", "1.0.0", None, Removed),
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("slicing_syntax", "1.0.0", None, Accepted),
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("box_syntax", "1.0.0", Some(27779), Active),
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("placement_in_syntax", "1.0.0", Some(27779), Active),
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// rustc internal.
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("pushpop_unsafe", "1.2.0", None, Active),
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("on_unimplemented", "1.0.0", Some(29628), Active),
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("simd_ffi", "1.0.0", Some(27731), Active),
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("allocator", "1.0.0", Some(27389), Active),
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("needs_allocator", "1.4.0", Some(27389), Active),
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("linked_from", "1.3.0", Some(29629), Active),
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("if_let", "1.0.0", None, Accepted),
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("while_let", "1.0.0", None, Accepted),
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("plugin", "1.0.0", Some(29597), Active),
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("start", "1.0.0", Some(29633), Active),
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("main", "1.0.0", Some(29634), Active),
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("fundamental", "1.0.0", Some(29635), Active),
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// A temporary feature gate used to enable parser extensions needed
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// to bootstrap fix for #5723.
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("issue_5723_bootstrap", "1.0.0", None, Accepted),
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// A way to temporarily opt out of opt in copy. This will *never* be accepted.
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("opt_out_copy", "1.0.0", None, Removed),
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// OIBIT specific features
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("optin_builtin_traits", "1.0.0", Some(13231), Active),
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// macro reexport needs more discussion and stabilization
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("macro_reexport", "1.0.0", Some(29638), Active),
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// These are used to test this portion of the compiler, they don't actually
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// mean anything
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("test_accepted_feature", "1.0.0", None, Accepted),
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("test_removed_feature", "1.0.0", None, Removed),
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// Allows use of #[staged_api]
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// rustc internal
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("staged_api", "1.0.0", None, Active),
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// Allows using items which are missing stability attributes
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// rustc internal
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("unmarked_api", "1.0.0", None, Active),
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// Allows using #![no_std]
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("no_std", "1.0.0", None, Accepted),
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// Allows using #![no_core]
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("no_core", "1.3.0", Some(29639), Active),
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// Allows using `box` in patterns; RFC 469
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("box_patterns", "1.0.0", Some(29641), Active),
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// Allows using the unsafe_no_drop_flag attribute (unlikely to
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// switch to Accepted; see RFC 320)
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("unsafe_no_drop_flag", "1.0.0", None, Active),
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// Allows using the unsafe_destructor_blind_to_params attribute;
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// RFC 1238
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("dropck_parametricity", "1.3.0", Some(28498), Active),
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// Allows the use of custom attributes; RFC 572
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("custom_attribute", "1.0.0", Some(29642), Active),
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// Allows the use of #[derive(Anything)] as sugar for
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// #[derive_Anything].
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("custom_derive", "1.0.0", Some(29644), Active),
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// Allows the use of rustc_* attributes; RFC 572
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("rustc_attrs", "1.0.0", Some(29642), Active),
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// Allows the use of #[allow_internal_unstable]. This is an
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// attribute on macro_rules! and can't use the attribute handling
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// below (it has to be checked before expansion possibly makes
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// macros disappear).
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//
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// rustc internal
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("allow_internal_unstable", "1.0.0", None, Active),
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// #23121. Array patterns have some hazards yet.
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("slice_patterns", "1.0.0", Some(23121), Active),
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// Allows use of unary negate on unsigned integers, e.g. -e for e: u8
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("negate_unsigned", "1.0.0", Some(29645), Removed),
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// Allows the definition of associated constants in `trait` or `impl`
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// blocks.
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("associated_consts", "1.0.0", Some(29646), Active),
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// Allows the definition of `const fn` functions.
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("const_fn", "1.2.0", Some(24111), Active),
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// Allows indexing into constant arrays.
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("const_indexing", "1.4.0", Some(29947), Active),
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// Allows using #[prelude_import] on glob `use` items.
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//
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// rustc internal
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("prelude_import", "1.2.0", None, Active),
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// Allows the definition recursive static items.
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("static_recursion", "1.3.0", Some(29719), Active),
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// Allows default type parameters to influence type inference.
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("default_type_parameter_fallback", "1.3.0", Some(27336), Active),
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// Allows associated type defaults
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("associated_type_defaults", "1.2.0", Some(29661), Active),
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// Allows macros to appear in the type position.
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("type_macros", "1.3.0", Some(27336), Active),
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// allow `repr(simd)`, and importing the various simd intrinsics
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("repr_simd", "1.4.0", Some(27731), Active),
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// Allows cfg(target_feature = "...").
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("cfg_target_feature", "1.4.0", Some(29717), Active),
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// allow `extern "platform-intrinsic" { ... }`
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("platform_intrinsics", "1.4.0", Some(27731), Active),
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// allow `#[unwind]`
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// rust runtime internal
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("unwind_attributes", "1.4.0", None, Active),
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// allow the use of `#[naked]` on functions.
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("naked_functions", "1.9.0", Some(32408), Active),
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// allow empty structs and enum variants with braces
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("braced_empty_structs", "1.5.0", Some(29720), Accepted),
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// allow overloading augmented assignment operations like `a += b`
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("augmented_assignments", "1.5.0", Some(28235), Accepted),
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// allow `#[no_debug]`
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("no_debug", "1.5.0", Some(29721), Active),
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// allow `#[omit_gdb_pretty_printer_section]`
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// rustc internal.
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("omit_gdb_pretty_printer_section", "1.5.0", None, Active),
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// Allows cfg(target_vendor = "...").
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("cfg_target_vendor", "1.5.0", Some(29718), Active),
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// Allow attributes on expressions and non-item statements
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("stmt_expr_attributes", "1.6.0", Some(15701), Active),
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// Allows `#[deprecated]` attribute
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("deprecated", "1.6.0", Some(29935), Active),
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// allow using type ascription in expressions
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("type_ascription", "1.6.0", Some(23416), Active),
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// Allows cfg(target_thread_local)
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("cfg_target_thread_local", "1.7.0", Some(29594), Active),
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// rustc internal
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("abi_vectorcall", "1.7.0", None, Active),
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// a...b and ...b
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("inclusive_range_syntax", "1.7.0", Some(28237), Active),
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// `expr?`
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("question_mark", "1.9.0", Some(31436), Active),
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// impl specialization (RFC 1210)
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("specialization", "1.7.0", Some(31844), Active),
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];
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// (changing above list without updating src/doc/reference.md makes @cmr sad)
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enum Status {
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/// Represents an active feature that is currently being implemented or
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/// currently being considered for addition/removal.
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Active,
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/// Represents a feature which has since been removed (it was once Active)
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Removed,
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/// This language feature has since been Accepted (it was once Active)
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Accepted,
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}
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// Attributes that have a special meaning to rustc or rustdoc
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pub const KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType, AttributeGate)] = &[
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// Normal attributes
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("warn", Normal, Ungated),
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("allow", Normal, Ungated),
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("forbid", Normal, Ungated),
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("deny", Normal, Ungated),
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("macro_reexport", Normal, Ungated),
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("macro_use", Normal, Ungated),
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("macro_export", Normal, Ungated),
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("plugin_registrar", Normal, Ungated),
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("cfg", Normal, Ungated),
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("cfg_attr", Normal, Ungated),
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("main", Normal, Ungated),
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("start", Normal, Ungated),
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("test", Normal, Ungated),
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("bench", Normal, Ungated),
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("simd", Normal, Ungated),
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("repr", Normal, Ungated),
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("path", Normal, Ungated),
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("abi", Normal, Ungated),
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("automatically_derived", Normal, Ungated),
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("no_mangle", Normal, Ungated),
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("no_link", Normal, Ungated),
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("derive", Normal, Ungated),
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("should_panic", Normal, Ungated),
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("ignore", Normal, Ungated),
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("no_implicit_prelude", Normal, Ungated),
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("reexport_test_harness_main", Normal, Ungated),
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("link_args", Normal, Ungated),
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("macro_escape", Normal, Ungated),
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// Not used any more, but we can't feature gate it
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("no_stack_check", Normal, Ungated),
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("plugin", CrateLevel, Gated("plugin",
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"compiler plugins are experimental \
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and possibly buggy")),
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("no_std", CrateLevel, Ungated),
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("no_core", CrateLevel, Gated("no_core",
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"no_core is experimental")),
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("lang", Normal, Gated("lang_items",
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"language items are subject to change")),
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("linkage", Whitelisted, Gated("linkage",
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"the `linkage` attribute is experimental \
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and not portable across platforms")),
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("thread_local", Whitelisted, Gated("thread_local",
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"`#[thread_local]` is an experimental feature, and does \
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not currently handle destructors. There is no \
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corresponding `#[task_local]` mapping to the task \
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model")),
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("rustc_on_unimplemented", Normal, Gated("on_unimplemented",
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"the `#[rustc_on_unimplemented]` attribute \
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is an experimental feature")),
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("allocator", Whitelisted, Gated("allocator",
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"the `#[allocator]` attribute is an experimental feature")),
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("needs_allocator", Normal, Gated("needs_allocator",
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"the `#[needs_allocator]` \
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attribute is an experimental \
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feature")),
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("rustc_variance", Normal, Gated("rustc_attrs",
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"the `#[rustc_variance]` attribute \
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is just used for rustc unit tests \
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and will never be stable")),
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("rustc_error", Whitelisted, Gated("rustc_attrs",
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"the `#[rustc_error]` attribute \
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is just used for rustc unit tests \
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and will never be stable")),
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("rustc_if_this_changed", Whitelisted, Gated("rustc_attrs",
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"the `#[rustc_if_this_changed]` attribute \
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is just used for rustc unit tests \
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and will never be stable")),
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("rustc_then_this_would_need", Whitelisted, Gated("rustc_attrs",
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"the `#[rustc_if_this_changed]` attribute \
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is just used for rustc unit tests \
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and will never be stable")),
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("rustc_move_fragments", Normal, Gated("rustc_attrs",
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"the `#[rustc_move_fragments]` attribute \
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is just used for rustc unit tests \
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and will never be stable")),
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("rustc_mir", Whitelisted, Gated("rustc_attrs",
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"the `#[rustc_mir]` attribute \
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is just used for rustc unit tests \
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and will never be stable")),
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("rustc_no_mir", Whitelisted, Gated("rustc_attrs",
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"the `#[rustc_no_mir]` attribute \
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is just used to make tests pass \
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and will never be stable")),
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("allow_internal_unstable", Normal, Gated("allow_internal_unstable",
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EXPLAIN_ALLOW_INTERNAL_UNSTABLE)),
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("fundamental", Whitelisted, Gated("fundamental",
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"the `#[fundamental]` attribute \
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is an experimental feature")),
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("linked_from", Normal, Gated("linked_from",
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"the `#[linked_from]` attribute \
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is an experimental feature")),
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// FIXME: #14408 whitelist docs since rustdoc looks at them
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("doc", Whitelisted, Ungated),
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// FIXME: #14406 these are processed in trans, which happens after the
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// lint pass
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("cold", Whitelisted, Ungated),
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("naked", Whitelisted, Gated("naked_functions",
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"the `#[naked]` attribute \
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is an experimental feature")),
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("export_name", Whitelisted, Ungated),
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("inline", Whitelisted, Ungated),
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("link", Whitelisted, Ungated),
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("link_name", Whitelisted, Ungated),
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("link_section", Whitelisted, Ungated),
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("no_builtins", Whitelisted, Ungated),
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("no_mangle", Whitelisted, Ungated),
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("no_debug", Whitelisted, Gated("no_debug",
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"the `#[no_debug]` attribute \
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is an experimental feature")),
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("omit_gdb_pretty_printer_section", Whitelisted, Gated("omit_gdb_pretty_printer_section",
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"the `#[omit_gdb_pretty_printer_section]` \
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attribute is just used for the Rust test \
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suite")),
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("unsafe_no_drop_flag", Whitelisted, Gated("unsafe_no_drop_flag",
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"unsafe_no_drop_flag has unstable semantics \
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and may be removed in the future")),
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("unsafe_destructor_blind_to_params",
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Normal,
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Gated("dropck_parametricity",
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"unsafe_destructor_blind_to_params has unstable semantics \
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and may be removed in the future")),
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("unwind", Whitelisted, Gated("unwind_attributes", "#[unwind] is experimental")),
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// used in resolve
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("prelude_import", Whitelisted, Gated("prelude_import",
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"`#[prelude_import]` is for use by rustc only")),
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// FIXME: #14407 these are only looked at on-demand so we can't
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// guarantee they'll have already been checked
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("rustc_deprecated", Whitelisted, Ungated),
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("must_use", Whitelisted, Ungated),
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("stable", Whitelisted, Ungated),
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("unstable", Whitelisted, Ungated),
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("deprecated", Normal, Gated("deprecated", "`#[deprecated]` attribute is unstable")),
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("rustc_paren_sugar", Normal, Gated("unboxed_closures",
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"unboxed_closures are still evolving")),
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("rustc_reflect_like", Whitelisted, Gated("reflect",
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"defining reflective traits is still evolving")),
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// Crate level attributes
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("crate_name", CrateLevel, Ungated),
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("crate_type", CrateLevel, Ungated),
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("crate_id", CrateLevel, Ungated),
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("feature", CrateLevel, Ungated),
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("no_start", CrateLevel, Ungated),
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("no_main", CrateLevel, Ungated),
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("no_builtins", CrateLevel, Ungated),
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("recursion_limit", CrateLevel, Ungated),
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];
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macro_rules! cfg_fn {
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(|$x: ident| $e: expr) => {{
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fn f($x: &Features) -> bool {
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$e
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}
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f as fn(&Features) -> bool
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}}
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}
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// cfg(...)'s that are feature gated
|
|
const GATED_CFGS: &'static [(&'static str, &'static str, fn(&Features) -> bool)] = &[
|
|
// (name in cfg, feature, function to check if the feature is enabled)
|
|
("target_feature", "cfg_target_feature", cfg_fn!(|x| x.cfg_target_feature)),
|
|
("target_vendor", "cfg_target_vendor", cfg_fn!(|x| x.cfg_target_vendor)),
|
|
("target_thread_local", "cfg_target_thread_local",
|
|
cfg_fn!(|x| x.cfg_target_thread_local)),
|
|
];
|
|
|
|
#[derive(Debug, Eq, PartialEq)]
|
|
pub enum GatedCfgAttr {
|
|
GatedCfg(GatedCfg),
|
|
GatedAttr(Span),
|
|
}
|
|
|
|
#[derive(Debug, Eq, PartialEq)]
|
|
pub struct GatedCfg {
|
|
span: Span,
|
|
index: usize,
|
|
}
|
|
|
|
impl Ord for GatedCfgAttr {
|
|
fn cmp(&self, other: &GatedCfgAttr) -> cmp::Ordering {
|
|
let to_tup = |s: &GatedCfgAttr| match *s {
|
|
GatedCfgAttr::GatedCfg(ref gated_cfg) => {
|
|
(gated_cfg.span.lo.0, gated_cfg.span.hi.0, gated_cfg.index)
|
|
}
|
|
GatedCfgAttr::GatedAttr(ref span) => {
|
|
(span.lo.0, span.hi.0, GATED_CFGS.len())
|
|
}
|
|
};
|
|
to_tup(self).cmp(&to_tup(other))
|
|
}
|
|
}
|
|
|
|
impl PartialOrd for GatedCfgAttr {
|
|
fn partial_cmp(&self, other: &GatedCfgAttr) -> Option<cmp::Ordering> {
|
|
Some(self.cmp(other))
|
|
}
|
|
}
|
|
|
|
impl GatedCfgAttr {
|
|
pub fn check_and_emit(&self,
|
|
diagnostic: &Handler,
|
|
features: &Features,
|
|
codemap: &CodeMap) {
|
|
match *self {
|
|
GatedCfgAttr::GatedCfg(ref cfg) => {
|
|
cfg.check_and_emit(diagnostic, features, codemap);
|
|
}
|
|
GatedCfgAttr::GatedAttr(span) => {
|
|
if !features.stmt_expr_attributes {
|
|
emit_feature_err(diagnostic,
|
|
"stmt_expr_attributes",
|
|
span,
|
|
GateIssue::Language,
|
|
EXPLAIN_STMT_ATTR_SYNTAX);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl GatedCfg {
|
|
pub fn gate(cfg: &ast::MetaItem) -> Option<GatedCfg> {
|
|
let name = cfg.name();
|
|
GATED_CFGS.iter()
|
|
.position(|info| info.0 == name)
|
|
.map(|idx| {
|
|
GatedCfg {
|
|
span: cfg.span,
|
|
index: idx
|
|
}
|
|
})
|
|
}
|
|
fn check_and_emit(&self,
|
|
diagnostic: &Handler,
|
|
features: &Features,
|
|
codemap: &CodeMap) {
|
|
let (cfg, feature, has_feature) = GATED_CFGS[self.index];
|
|
if !has_feature(features) && !codemap.span_allows_unstable(self.span) {
|
|
let explain = format!("`cfg({})` is experimental and subject to change", cfg);
|
|
emit_feature_err(diagnostic, feature, self.span, GateIssue::Language, &explain);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
#[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,
|
|
}
|
|
|
|
#[derive(PartialEq, Copy, Clone, Debug)]
|
|
pub enum AttributeGate {
|
|
/// Is gated by a given feature gate and reason
|
|
Gated(&'static str, &'static str),
|
|
|
|
/// Ungated attribute, can be used on all release channels
|
|
Ungated,
|
|
}
|
|
|
|
/// A set of features to be used by later passes.
|
|
pub struct Features {
|
|
pub unboxed_closures: bool,
|
|
pub rustc_diagnostic_macros: bool,
|
|
pub allow_quote: bool,
|
|
pub allow_asm: bool,
|
|
pub allow_log_syntax: bool,
|
|
pub allow_concat_idents: bool,
|
|
pub allow_trace_macros: bool,
|
|
pub allow_internal_unstable: bool,
|
|
pub allow_custom_derive: bool,
|
|
pub allow_placement_in: bool,
|
|
pub allow_box: bool,
|
|
pub allow_pushpop_unsafe: bool,
|
|
pub allow_inclusive_range: bool,
|
|
pub simd_ffi: bool,
|
|
pub unmarked_api: bool,
|
|
/// spans of #![feature] attrs for stable language features. for error reporting
|
|
pub declared_stable_lang_features: Vec<Span>,
|
|
/// #![feature] attrs for non-language (library) features
|
|
pub declared_lib_features: Vec<(InternedString, Span)>,
|
|
pub const_fn: bool,
|
|
pub const_indexing: bool,
|
|
pub static_recursion: bool,
|
|
pub default_type_parameter_fallback: bool,
|
|
pub type_macros: bool,
|
|
pub cfg_target_feature: bool,
|
|
pub cfg_target_vendor: bool,
|
|
pub cfg_target_thread_local: bool,
|
|
pub staged_api: bool,
|
|
pub stmt_expr_attributes: bool,
|
|
pub deprecated: bool,
|
|
pub question_mark: bool,
|
|
pub specialization: bool,
|
|
}
|
|
|
|
impl Features {
|
|
pub fn new() -> Features {
|
|
Features {
|
|
unboxed_closures: false,
|
|
rustc_diagnostic_macros: false,
|
|
allow_quote: false,
|
|
allow_asm: false,
|
|
allow_log_syntax: false,
|
|
allow_concat_idents: false,
|
|
allow_trace_macros: false,
|
|
allow_internal_unstable: false,
|
|
allow_custom_derive: false,
|
|
allow_placement_in: false,
|
|
allow_box: false,
|
|
allow_pushpop_unsafe: false,
|
|
allow_inclusive_range: false,
|
|
simd_ffi: false,
|
|
unmarked_api: false,
|
|
declared_stable_lang_features: Vec::new(),
|
|
declared_lib_features: Vec::new(),
|
|
const_fn: false,
|
|
const_indexing: false,
|
|
static_recursion: false,
|
|
default_type_parameter_fallback: false,
|
|
type_macros: false,
|
|
cfg_target_feature: false,
|
|
cfg_target_vendor: false,
|
|
cfg_target_thread_local: false,
|
|
staged_api: false,
|
|
stmt_expr_attributes: false,
|
|
deprecated: false,
|
|
question_mark: false,
|
|
specialization: false,
|
|
}
|
|
}
|
|
}
|
|
|
|
const EXPLAIN_BOX_SYNTAX: &'static str =
|
|
"box expression syntax is experimental; you can call `Box::new` instead.";
|
|
|
|
const EXPLAIN_PLACEMENT_IN: &'static str =
|
|
"placement-in expression syntax is experimental and subject to change.";
|
|
|
|
const EXPLAIN_PUSHPOP_UNSAFE: &'static str =
|
|
"push/pop_unsafe macros are experimental and subject to change.";
|
|
|
|
const EXPLAIN_STMT_ATTR_SYNTAX: &'static str =
|
|
"attributes on non-item statements and expressions are experimental.";
|
|
|
|
pub fn check_for_box_syntax(f: Option<&Features>, diag: &Handler, span: Span) {
|
|
if let Some(&Features { allow_box: true, .. }) = f {
|
|
return;
|
|
}
|
|
emit_feature_err(diag, "box_syntax", span, GateIssue::Language, EXPLAIN_BOX_SYNTAX);
|
|
}
|
|
|
|
pub fn check_for_placement_in(f: Option<&Features>, diag: &Handler, span: Span) {
|
|
if let Some(&Features { allow_placement_in: true, .. }) = f {
|
|
return;
|
|
}
|
|
emit_feature_err(diag, "placement_in_syntax", span, GateIssue::Language, EXPLAIN_PLACEMENT_IN);
|
|
}
|
|
|
|
pub fn check_for_pushpop_syntax(f: Option<&Features>, diag: &Handler, span: Span) {
|
|
if let Some(&Features { allow_pushpop_unsafe: true, .. }) = f {
|
|
return;
|
|
}
|
|
emit_feature_err(diag, "pushpop_unsafe", span, GateIssue::Language, EXPLAIN_PUSHPOP_UNSAFE);
|
|
}
|
|
|
|
struct Context<'a> {
|
|
features: Vec<&'static str>,
|
|
span_handler: &'a Handler,
|
|
cm: &'a CodeMap,
|
|
plugin_attributes: &'a [(String, AttributeType)],
|
|
}
|
|
|
|
impl<'a> Context<'a> {
|
|
fn enable_feature(&mut self, feature: &'static str) {
|
|
debug!("enabling feature: {}", feature);
|
|
self.features.push(feature);
|
|
}
|
|
|
|
fn gate_feature(&self, feature: &str, span: Span, explain: &str) {
|
|
let has_feature = self.has_feature(feature);
|
|
debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", feature, span, has_feature);
|
|
if !has_feature {
|
|
emit_feature_err(self.span_handler, feature, span, GateIssue::Language, explain);
|
|
}
|
|
}
|
|
fn has_feature(&self, feature: &str) -> bool {
|
|
self.features.iter().any(|&n| n == feature)
|
|
}
|
|
|
|
fn check_attribute(&self, attr: &ast::Attribute, is_macro: bool) {
|
|
debug!("check_attribute(attr = {:?})", attr);
|
|
let name = &*attr.name();
|
|
for &(n, ty, gateage) in KNOWN_ATTRIBUTES {
|
|
if n == name {
|
|
if let Gated(gate, desc) = gateage {
|
|
self.gate_feature(gate, attr.span, desc);
|
|
}
|
|
debug!("check_attribute: {:?} is known, {:?}, {:?}", name, ty, gateage);
|
|
return;
|
|
}
|
|
}
|
|
for &(ref n, ref ty) in self.plugin_attributes {
|
|
if n == name {
|
|
// 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, {:?}", name, ty);
|
|
return;
|
|
}
|
|
}
|
|
if name.starts_with("rustc_") {
|
|
self.gate_feature("rustc_attrs", attr.span,
|
|
"unless otherwise specified, attributes \
|
|
with the prefix `rustc_` \
|
|
are reserved for internal compiler diagnostics");
|
|
} else if name.starts_with("derive_") {
|
|
self.gate_feature("custom_derive", attr.span,
|
|
"attributes of the form `#[derive_*]` are reserved \
|
|
for the compiler");
|
|
} else {
|
|
// 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 {
|
|
self.gate_feature("custom_attribute", attr.span,
|
|
&format!("The attribute `{}` is currently \
|
|
unknown to the compiler and \
|
|
may have meaning \
|
|
added to it in the future",
|
|
name));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn find_lang_feature_issue(feature: &str) -> Option<u32> {
|
|
let info = KNOWN_FEATURES.iter()
|
|
.find(|t| t.0 == feature)
|
|
.unwrap();
|
|
let issue = info.2;
|
|
if let Active = info.3 {
|
|
// FIXME (#28244): enforce that active features have issue numbers
|
|
// assert!(issue.is_some())
|
|
}
|
|
issue
|
|
}
|
|
|
|
pub enum GateIssue {
|
|
Language,
|
|
Library(Option<u32>)
|
|
}
|
|
|
|
pub fn emit_feature_err(diag: &Handler, feature: &str, span: Span, issue: GateIssue,
|
|
explain: &str) {
|
|
let issue = match issue {
|
|
GateIssue::Language => find_lang_feature_issue(feature),
|
|
GateIssue::Library(lib) => lib,
|
|
};
|
|
|
|
let mut err = if let Some(n) = issue {
|
|
diag.struct_span_err(span, &format!("{} (see issue #{})", explain, n))
|
|
} else {
|
|
diag.struct_span_err(span, explain)
|
|
};
|
|
|
|
// #23973: do not suggest `#![feature(...)]` if we are in beta/stable
|
|
if option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some() {
|
|
err.emit();
|
|
return;
|
|
}
|
|
err.fileline_help(span, &format!("add #![feature({})] to the \
|
|
crate attributes to enable",
|
|
feature));
|
|
err.emit();
|
|
}
|
|
|
|
pub const EXPLAIN_ASM: &'static str =
|
|
"inline assembly 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_CUSTOM_DERIVE: &'static str =
|
|
"`#[derive]` for custom traits is not stable enough for use and is subject to change";
|
|
|
|
struct MacroVisitor<'a> {
|
|
context: &'a Context<'a>
|
|
}
|
|
|
|
impl<'a, 'v> Visitor<'v> for MacroVisitor<'a> {
|
|
fn visit_mac(&mut self, mac: &ast::Mac) {
|
|
let path = &mac.node.path;
|
|
let name = path.segments.last().unwrap().identifier.name.as_str();
|
|
|
|
// Issue 22234: If you add a new case here, make sure to also
|
|
// add code to catch the macro during or after expansion.
|
|
//
|
|
// We still keep this MacroVisitor (rather than *solely*
|
|
// relying on catching cases during or after expansion) to
|
|
// catch uses of these macros within conditionally-compiled
|
|
// code, e.g. `#[cfg]`-guarded functions.
|
|
|
|
if name == "asm" {
|
|
self.context.gate_feature("asm", path.span, EXPLAIN_ASM);
|
|
}
|
|
|
|
else if name == "log_syntax" {
|
|
self.context.gate_feature("log_syntax", path.span, EXPLAIN_LOG_SYNTAX);
|
|
}
|
|
|
|
else if name == "trace_macros" {
|
|
self.context.gate_feature("trace_macros", path.span, EXPLAIN_TRACE_MACROS);
|
|
}
|
|
|
|
else if name == "concat_idents" {
|
|
self.context.gate_feature("concat_idents", path.span, EXPLAIN_CONCAT_IDENTS);
|
|
}
|
|
}
|
|
|
|
fn visit_attribute(&mut self, attr: &'v ast::Attribute) {
|
|
self.context.check_attribute(attr, true);
|
|
}
|
|
|
|
fn visit_expr(&mut self, e: &ast::Expr) {
|
|
// Issue 22181: overloaded-`box` and placement-`in` are
|
|
// implemented via a desugaring expansion, so their feature
|
|
// gates go into MacroVisitor since that works pre-expansion.
|
|
//
|
|
// Issue 22234: we also check during expansion as well.
|
|
// But we keep these checks as a pre-expansion check to catch
|
|
// uses in e.g. conditionalized code.
|
|
|
|
if let ast::ExprKind::Box(_) = e.node {
|
|
self.context.gate_feature("box_syntax", e.span, EXPLAIN_BOX_SYNTAX);
|
|
}
|
|
|
|
if let ast::ExprKind::InPlace(..) = e.node {
|
|
self.context.gate_feature("placement_in_syntax", e.span, EXPLAIN_PLACEMENT_IN);
|
|
}
|
|
|
|
visit::walk_expr(self, e);
|
|
}
|
|
}
|
|
|
|
struct PostExpansionVisitor<'a> {
|
|
context: &'a Context<'a>,
|
|
}
|
|
|
|
impl<'a> PostExpansionVisitor<'a> {
|
|
fn gate_feature(&self, feature: &str, span: Span, explain: &str) {
|
|
if !self.context.cm.span_allows_unstable(span) {
|
|
self.context.gate_feature(feature, span, explain)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, 'v> Visitor<'v> for PostExpansionVisitor<'a> {
|
|
fn visit_attribute(&mut self, attr: &ast::Attribute) {
|
|
if !self.context.cm.span_allows_unstable(attr.span) {
|
|
self.context.check_attribute(attr, false);
|
|
}
|
|
}
|
|
|
|
fn visit_name(&mut self, sp: Span, name: ast::Name) {
|
|
if !name.as_str().is_ascii() {
|
|
self.gate_feature("non_ascii_idents", sp,
|
|
"non-ascii idents are not fully supported.");
|
|
}
|
|
}
|
|
|
|
fn visit_item(&mut self, i: &ast::Item) {
|
|
match i.node {
|
|
ast::ItemKind::ExternCrate(_) => {
|
|
if attr::contains_name(&i.attrs[..], "macro_reexport") {
|
|
self.gate_feature("macro_reexport", i.span,
|
|
"macros reexports are experimental \
|
|
and possibly buggy");
|
|
}
|
|
}
|
|
|
|
ast::ItemKind::ForeignMod(ref foreign_module) => {
|
|
if attr::contains_name(&i.attrs[..], "link_args") {
|
|
self.gate_feature("link_args", i.span,
|
|
"the `link_args` attribute is not portable \
|
|
across platforms, it is recommended to \
|
|
use `#[link(name = \"foo\")]` instead")
|
|
}
|
|
let maybe_feature = match foreign_module.abi {
|
|
Abi::RustIntrinsic => Some(("intrinsics", "intrinsics are subject to change")),
|
|
Abi::PlatformIntrinsic => {
|
|
Some(("platform_intrinsics",
|
|
"platform intrinsics are experimental and possibly buggy"))
|
|
},
|
|
Abi::Vectorcall => {
|
|
Some(("abi_vectorcall",
|
|
"vectorcall is experimental and subject to change"
|
|
))
|
|
}
|
|
_ => None
|
|
};
|
|
if let Some((feature, msg)) = maybe_feature {
|
|
self.gate_feature(feature, i.span, msg)
|
|
}
|
|
}
|
|
|
|
ast::ItemKind::Fn(..) => {
|
|
if attr::contains_name(&i.attrs[..], "plugin_registrar") {
|
|
self.gate_feature("plugin_registrar", i.span,
|
|
"compiler plugins are experimental and possibly buggy");
|
|
}
|
|
if attr::contains_name(&i.attrs[..], "start") {
|
|
self.gate_feature("start", i.span,
|
|
"a #[start] function is an experimental \
|
|
feature whose signature may change \
|
|
over time");
|
|
}
|
|
if attr::contains_name(&i.attrs[..], "main") {
|
|
self.gate_feature("main", i.span,
|
|
"declaration of a nonstandard #[main] \
|
|
function may change over time, for now \
|
|
a top-level `fn main()` is required");
|
|
}
|
|
}
|
|
|
|
ast::ItemKind::Struct(..) => {
|
|
if attr::contains_name(&i.attrs[..], "simd") {
|
|
self.gate_feature("simd", i.span,
|
|
"SIMD types are experimental and possibly buggy");
|
|
self.context.span_handler.span_warn(i.span,
|
|
"the `#[simd]` attribute is deprecated, \
|
|
use `#[repr(simd)]` instead");
|
|
}
|
|
for attr in &i.attrs {
|
|
if attr.name() == "repr" {
|
|
for item in attr.meta_item_list().unwrap_or(&[]) {
|
|
if item.name() == "simd" {
|
|
self.gate_feature("repr_simd", i.span,
|
|
"SIMD types are experimental and possibly buggy");
|
|
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
ast::ItemKind::DefaultImpl(..) => {
|
|
self.gate_feature("optin_builtin_traits",
|
|
i.span,
|
|
"default trait implementations are experimental \
|
|
and possibly buggy");
|
|
}
|
|
|
|
ast::ItemKind::Impl(_, polarity, _, _, _, _) => {
|
|
match polarity {
|
|
ast::ImplPolarity::Negative => {
|
|
self.gate_feature("optin_builtin_traits",
|
|
i.span,
|
|
"negative trait bounds are not yet fully implemented; \
|
|
use marker types for now");
|
|
},
|
|
_ => {}
|
|
}
|
|
}
|
|
|
|
_ => {}
|
|
}
|
|
|
|
visit::walk_item(self, i);
|
|
}
|
|
|
|
fn visit_variant_data(&mut self, s: &'v ast::VariantData, _: ast::Ident,
|
|
_: &'v ast::Generics, _: ast::NodeId, span: Span) {
|
|
if s.fields().is_empty() {
|
|
if s.is_tuple() {
|
|
self.context.span_handler.struct_span_err(span, "empty tuple structs and enum \
|
|
variants are not allowed, use \
|
|
unit structs and enum variants \
|
|
instead")
|
|
.span_help(span, "remove trailing `()` to make a unit \
|
|
struct or unit enum variant")
|
|
.emit();
|
|
}
|
|
}
|
|
visit::walk_struct_def(self, s)
|
|
}
|
|
|
|
fn visit_foreign_item(&mut self, i: &ast::ForeignItem) {
|
|
let links_to_llvm = match attr::first_attr_value_str_by_name(&i.attrs,
|
|
"link_name") {
|
|
Some(val) => val.starts_with("llvm."),
|
|
_ => false
|
|
};
|
|
if links_to_llvm {
|
|
self.gate_feature("link_llvm_intrinsics", i.span,
|
|
"linking to LLVM intrinsics is experimental");
|
|
}
|
|
|
|
visit::walk_foreign_item(self, i)
|
|
}
|
|
|
|
fn visit_expr(&mut self, e: &ast::Expr) {
|
|
match e.node {
|
|
ast::ExprKind::Box(_) => {
|
|
self.gate_feature("box_syntax",
|
|
e.span,
|
|
"box expression syntax is experimental; \
|
|
you can call `Box::new` instead.");
|
|
}
|
|
ast::ExprKind::Type(..) => {
|
|
self.gate_feature("type_ascription", e.span,
|
|
"type ascription is experimental");
|
|
}
|
|
ast::ExprKind::Range(_, _, ast::RangeLimits::Closed) => {
|
|
self.gate_feature("inclusive_range_syntax",
|
|
e.span,
|
|
"inclusive range syntax is experimental");
|
|
}
|
|
ast::ExprKind::Try(..) => {
|
|
self.gate_feature("question_mark", e.span, "the `?` operator is not stable");
|
|
}
|
|
_ => {}
|
|
}
|
|
visit::walk_expr(self, e);
|
|
}
|
|
|
|
fn visit_pat(&mut self, pattern: &ast::Pat) {
|
|
match pattern.node {
|
|
PatKind::Vec(_, Some(_), ref last) if !last.is_empty() => {
|
|
self.gate_feature("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::Vec(..) => {
|
|
self.gate_feature("slice_patterns",
|
|
pattern.span,
|
|
"slice pattern syntax is experimental");
|
|
}
|
|
PatKind::Box(..) => {
|
|
self.gate_feature("box_patterns",
|
|
pattern.span,
|
|
"box pattern syntax is experimental");
|
|
}
|
|
_ => {}
|
|
}
|
|
visit::walk_pat(self, pattern)
|
|
}
|
|
|
|
fn visit_fn(&mut self,
|
|
fn_kind: FnKind<'v>,
|
|
fn_decl: &'v ast::FnDecl,
|
|
block: &'v ast::Block,
|
|
span: Span,
|
|
_node_id: NodeId) {
|
|
// check for const fn declarations
|
|
match fn_kind {
|
|
FnKind::ItemFn(_, _, _, ast::Constness::Const, _, _) => {
|
|
self.gate_feature("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, _) if abi == Abi::RustIntrinsic => {
|
|
self.gate_feature("intrinsics",
|
|
span,
|
|
"intrinsics are subject to change")
|
|
}
|
|
FnKind::ItemFn(_, _, _, _, abi, _) |
|
|
FnKind::Method(_, &ast::MethodSig { abi, .. }, _) => match abi {
|
|
Abi::RustCall => {
|
|
self.gate_feature("unboxed_closures", span,
|
|
"rust-call ABI is subject to change");
|
|
},
|
|
Abi::Vectorcall => {
|
|
self.gate_feature("abi_vectorcall", span,
|
|
"vectorcall is experimental and subject to change");
|
|
},
|
|
_ => {}
|
|
},
|
|
_ => {}
|
|
}
|
|
visit::walk_fn(self, fn_kind, fn_decl, block, span);
|
|
}
|
|
|
|
fn visit_trait_item(&mut self, ti: &'v ast::TraitItem) {
|
|
match ti.node {
|
|
ast::TraitItemKind::Const(..) => {
|
|
self.gate_feature("associated_consts",
|
|
ti.span,
|
|
"associated constants are experimental")
|
|
}
|
|
ast::TraitItemKind::Method(ref sig, _) => {
|
|
if sig.constness == ast::Constness::Const {
|
|
self.gate_feature("const_fn", ti.span, "const fn is unstable");
|
|
}
|
|
}
|
|
ast::TraitItemKind::Type(_, Some(_)) => {
|
|
self.gate_feature("associated_type_defaults", ti.span,
|
|
"associated type defaults are unstable");
|
|
}
|
|
_ => {}
|
|
}
|
|
visit::walk_trait_item(self, ti);
|
|
}
|
|
|
|
fn visit_impl_item(&mut self, ii: &'v ast::ImplItem) {
|
|
if ii.defaultness == ast::Defaultness::Default {
|
|
self.gate_feature("specialization",
|
|
ii.span,
|
|
"specialization is unstable");
|
|
}
|
|
|
|
match ii.node {
|
|
ast::ImplItemKind::Const(..) => {
|
|
self.gate_feature("associated_consts",
|
|
ii.span,
|
|
"associated constants are experimental")
|
|
}
|
|
ast::ImplItemKind::Method(ref sig, _) => {
|
|
if sig.constness == ast::Constness::Const {
|
|
self.gate_feature("const_fn", ii.span, "const fn is unstable");
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
visit::walk_impl_item(self, ii);
|
|
}
|
|
}
|
|
|
|
fn check_crate_inner<F>(cm: &CodeMap, span_handler: &Handler,
|
|
krate: &ast::Crate,
|
|
plugin_attributes: &[(String, AttributeType)],
|
|
check: F)
|
|
-> Features
|
|
where F: FnOnce(&mut Context, &ast::Crate)
|
|
{
|
|
let mut cx = Context {
|
|
features: Vec::new(),
|
|
span_handler: span_handler,
|
|
cm: cm,
|
|
plugin_attributes: plugin_attributes,
|
|
};
|
|
|
|
let mut accepted_features = Vec::new();
|
|
let mut unknown_features = Vec::new();
|
|
|
|
for attr in &krate.attrs {
|
|
if !attr.check_name("feature") {
|
|
continue
|
|
}
|
|
|
|
match attr.meta_item_list() {
|
|
None => {
|
|
span_handler.span_err(attr.span, "malformed feature attribute, \
|
|
expected #![feature(...)]");
|
|
}
|
|
Some(list) => {
|
|
for mi in list {
|
|
let name = match mi.node {
|
|
ast::MetaItemKind::Word(ref word) => (*word).clone(),
|
|
_ => {
|
|
span_handler.span_err(mi.span,
|
|
"malformed feature, expected just \
|
|
one word");
|
|
continue
|
|
}
|
|
};
|
|
match KNOWN_FEATURES.iter()
|
|
.find(|& &(n, _, _, _)| name == n) {
|
|
Some(&(name, _, _, Active)) => {
|
|
cx.enable_feature(name);
|
|
}
|
|
Some(&(_, _, _, Removed)) => {
|
|
span_handler.span_err(mi.span, "feature has been removed");
|
|
}
|
|
Some(&(_, _, _, Accepted)) => {
|
|
accepted_features.push(mi.span);
|
|
}
|
|
None => {
|
|
unknown_features.push((name, mi.span));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
check(&mut cx, krate);
|
|
|
|
// FIXME (pnkfelix): Before adding the 99th entry below, change it
|
|
// to a single-pass (instead of N calls to `.has_feature`).
|
|
|
|
Features {
|
|
unboxed_closures: cx.has_feature("unboxed_closures"),
|
|
rustc_diagnostic_macros: cx.has_feature("rustc_diagnostic_macros"),
|
|
allow_quote: cx.has_feature("quote"),
|
|
allow_asm: cx.has_feature("asm"),
|
|
allow_log_syntax: cx.has_feature("log_syntax"),
|
|
allow_concat_idents: cx.has_feature("concat_idents"),
|
|
allow_trace_macros: cx.has_feature("trace_macros"),
|
|
allow_internal_unstable: cx.has_feature("allow_internal_unstable"),
|
|
allow_custom_derive: cx.has_feature("custom_derive"),
|
|
allow_placement_in: cx.has_feature("placement_in_syntax"),
|
|
allow_box: cx.has_feature("box_syntax"),
|
|
allow_pushpop_unsafe: cx.has_feature("pushpop_unsafe"),
|
|
allow_inclusive_range: cx.has_feature("inclusive_range_syntax"),
|
|
simd_ffi: cx.has_feature("simd_ffi"),
|
|
unmarked_api: cx.has_feature("unmarked_api"),
|
|
declared_stable_lang_features: accepted_features,
|
|
declared_lib_features: unknown_features,
|
|
const_fn: cx.has_feature("const_fn"),
|
|
const_indexing: cx.has_feature("const_indexing"),
|
|
static_recursion: cx.has_feature("static_recursion"),
|
|
default_type_parameter_fallback: cx.has_feature("default_type_parameter_fallback"),
|
|
type_macros: cx.has_feature("type_macros"),
|
|
cfg_target_feature: cx.has_feature("cfg_target_feature"),
|
|
cfg_target_vendor: cx.has_feature("cfg_target_vendor"),
|
|
cfg_target_thread_local: cx.has_feature("cfg_target_thread_local"),
|
|
staged_api: cx.has_feature("staged_api"),
|
|
stmt_expr_attributes: cx.has_feature("stmt_expr_attributes"),
|
|
deprecated: cx.has_feature("deprecated"),
|
|
question_mark: cx.has_feature("question_mark"),
|
|
specialization: cx.has_feature("specialization"),
|
|
}
|
|
}
|
|
|
|
pub fn check_crate_macros(cm: &CodeMap, span_handler: &Handler, krate: &ast::Crate)
|
|
-> Features {
|
|
check_crate_inner(cm, span_handler, krate, &[] as &'static [_],
|
|
|ctx, krate| visit::walk_crate(&mut MacroVisitor { context: ctx }, krate))
|
|
}
|
|
|
|
pub fn check_crate(cm: &CodeMap, span_handler: &Handler, krate: &ast::Crate,
|
|
plugin_attributes: &[(String, AttributeType)],
|
|
unstable: UnstableFeatures) -> Features
|
|
{
|
|
maybe_stage_features(span_handler, krate, unstable);
|
|
|
|
check_crate_inner(cm, span_handler, krate, plugin_attributes,
|
|
|ctx, krate| visit::walk_crate(&mut PostExpansionVisitor { context: ctx },
|
|
krate))
|
|
}
|
|
|
|
#[derive(Clone, Copy)]
|
|
pub enum UnstableFeatures {
|
|
/// Hard errors for unstable features are active, as on
|
|
/// beta/stable channels.
|
|
Disallow,
|
|
/// Allow features to me 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
|
|
}
|
|
|
|
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)");
|
|
let ref msg = format!("#[feature] may not be used on the {} release channel",
|
|
release_channel);
|
|
span_handler.span_err(attr.span, msg);
|
|
}
|
|
}
|
|
}
|
|
}
|