489a6c95bf
The extra filename and line was mainly there to keep the indentation relative to the main snippet; now that this doesn't include filename/line-number as a prefix, it is distracted.
1214 lines
49 KiB
Rust
1214 lines
49 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::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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macro_rules! setter {
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($field: ident) => {{
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fn f(features: &mut Features) -> &mut bool {
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&mut features.$field
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}
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f as fn(&mut Features) -> &mut bool
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}}
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}
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macro_rules! declare_features {
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($((active, $feature: ident, $ver: expr, $issue: expr)),+) => {
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/// Represents active features that are currently being implemented or
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/// currently being considered for addition/removal.
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const ACTIVE_FEATURES: &'static [(&'static str, &'static str,
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Option<u32>, fn(&mut Features) -> &mut bool)] = &[
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$((stringify!($feature), $ver, $issue, setter!($feature))),+
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];
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/// A set of features to be used by later passes.
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pub struct Features {
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/// spans of #![feature] attrs for stable language features. for error reporting
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pub declared_stable_lang_features: Vec<Span>,
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/// #![feature] attrs for non-language (library) features
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pub declared_lib_features: Vec<(InternedString, Span)>,
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$(pub $feature: bool),+
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}
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impl Features {
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pub fn new() -> Features {
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Features {
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declared_stable_lang_features: Vec::new(),
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declared_lib_features: Vec::new(),
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$($feature: false),+
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}
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}
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}
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};
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($((removed, $feature: ident, $ver: expr, $issue: expr)),+) => {
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/// Represents features which has since been removed (it was once Active)
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const REMOVED_FEATURES: &'static [(&'static str, &'static str, Option<u32>)] = &[
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$((stringify!($feature), $ver, $issue)),+
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];
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};
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($((accepted, $feature: ident, $ver: expr, $issue: expr)),+) => {
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/// Those language feature has since been Accepted (it was once Active)
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const ACCEPTED_FEATURES: &'static [(&'static str, &'static str, Option<u32>)] = &[
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$((stringify!($feature), $ver, $issue)),+
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];
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}
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}
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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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declare_features! (
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(active, asm, "1.0.0", Some(29722)),
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(active, concat_idents, "1.0.0", Some(29599)),
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(active, link_args, "1.0.0", Some(29596)),
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(active, log_syntax, "1.0.0", Some(29598)),
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(active, non_ascii_idents, "1.0.0", Some(28979)),
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(active, plugin_registrar, "1.0.0", Some(29597)),
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(active, thread_local, "1.0.0", Some(29594)),
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(active, trace_macros, "1.0.0", Some(29598)),
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// rustc internal, for now:
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(active, intrinsics, "1.0.0", None),
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(active, lang_items, "1.0.0", None),
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(active, link_llvm_intrinsics, "1.0.0", Some(29602)),
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(active, linkage, "1.0.0", Some(29603)),
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(active, quote, "1.0.0", Some(29601)),
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(active, simd, "1.0.0", Some(27731)),
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// rustc internal
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(active, rustc_diagnostic_macros, "1.0.0", None),
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(active, advanced_slice_patterns, "1.0.0", Some(23121)),
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(active, box_syntax, "1.0.0", Some(27779)),
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(active, placement_in_syntax, "1.0.0", Some(27779)),
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(active, reflect, "1.0.0", Some(27749)),
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(active, unboxed_closures, "1.0.0", Some(29625)),
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// rustc internal.
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(active, pushpop_unsafe, "1.2.0", None),
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(active, allocator, "1.0.0", Some(27389)),
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(active, fundamental, "1.0.0", Some(29635)),
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(active, linked_from, "1.3.0", Some(29629)),
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(active, main, "1.0.0", Some(29634)),
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(active, needs_allocator, "1.4.0", Some(27389)),
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(active, on_unimplemented, "1.0.0", Some(29628)),
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(active, plugin, "1.0.0", Some(29597)),
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(active, simd_ffi, "1.0.0", Some(27731)),
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(active, start, "1.0.0", Some(29633)),
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(active, structural_match, "1.8.0", Some(31434)),
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// OIBIT specific features
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(active, optin_builtin_traits, "1.0.0", Some(13231)),
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// macro reexport needs more discussion and stabilization
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(active, macro_reexport, "1.0.0", Some(29638)),
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// Allows use of #[staged_api]
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// rustc internal
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(active, staged_api, "1.0.0", None),
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// Allows using items which are missing stability attributes
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// rustc internal
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(active, unmarked_api, "1.0.0", None),
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// Allows using #![no_core]
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(active, no_core, "1.3.0", Some(29639)),
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// Allows using `box` in patterns; RFC 469
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(active, box_patterns, "1.0.0", Some(29641)),
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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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(active, unsafe_no_drop_flag, "1.0.0", None),
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// Allows using the unsafe_destructor_blind_to_params attribute;
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// RFC 1238
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(active, dropck_parametricity, "1.3.0", Some(28498)),
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// Allows the use of custom attributes; RFC 572
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(active, custom_attribute, "1.0.0", Some(29642)),
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// Allows the use of #[derive(Anything)] as sugar for
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// #[derive_Anything].
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(active, custom_derive, "1.0.0", Some(29644)),
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// Allows the use of rustc_* attributes; RFC 572
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(active, rustc_attrs, "1.0.0", Some(29642)),
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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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(active, allow_internal_unstable, "1.0.0", None),
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// #23121. Array patterns have some hazards yet.
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(active, slice_patterns, "1.0.0", Some(23121)),
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// Allows the definition of associated constants in `trait` or `impl`
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// blocks.
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(active, associated_consts, "1.0.0", Some(29646)),
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// Allows the definition of `const fn` functions.
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(active, const_fn, "1.2.0", Some(24111)),
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// Allows indexing into constant arrays.
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(active, const_indexing, "1.4.0", Some(29947)),
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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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(active, prelude_import, "1.2.0", None),
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// Allows the definition recursive static items.
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(active, static_recursion, "1.3.0", Some(29719)),
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// Allows default type parameters to influence type inference.
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(active, default_type_parameter_fallback, "1.3.0", Some(27336)),
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// Allows associated type defaults
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(active, associated_type_defaults, "1.2.0", Some(29661)),
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// Allows macros to appear in the type position.
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(active, type_macros, "1.3.0", Some(27245)),
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// allow `repr(simd)`, and importing the various simd intrinsics
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(active, repr_simd, "1.4.0", Some(27731)),
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// Allows cfg(target_feature = "...").
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(active, cfg_target_feature, "1.4.0", Some(29717)),
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// allow `extern "platform-intrinsic" { ... }`
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(active, platform_intrinsics, "1.4.0", Some(27731)),
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// allow `#[unwind]`
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// rust runtime internal
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(active, unwind_attributes, "1.4.0", None),
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// allow the use of `#[naked]` on functions.
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(active, naked_functions, "1.9.0", Some(32408)),
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// allow `#[no_debug]`
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(active, no_debug, "1.5.0", Some(29721)),
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// allow `#[omit_gdb_pretty_printer_section]`
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// rustc internal.
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(active, omit_gdb_pretty_printer_section, "1.5.0", None),
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// Allows cfg(target_vendor = "...").
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(active, cfg_target_vendor, "1.5.0", Some(29718)),
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// Allow attributes on expressions and non-item statements
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(active, stmt_expr_attributes, "1.6.0", Some(15701)),
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// allow using type ascription in expressions
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(active, type_ascription, "1.6.0", Some(23416)),
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// Allows cfg(target_thread_local)
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(active, cfg_target_thread_local, "1.7.0", Some(29594)),
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// rustc internal
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(active, abi_vectorcall, "1.7.0", None),
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// a...b and ...b
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(active, inclusive_range_syntax, "1.7.0", Some(28237)),
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// `expr?`
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(active, question_mark, "1.9.0", Some(31436)),
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// impl specialization (RFC 1210)
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(active, specialization, "1.7.0", Some(31844)),
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// pub(restricted) visibilities (RFC 1422)
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(active, pub_restricted, "1.9.0", Some(32409))
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);
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declare_features! (
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(removed, import_shadowing, "1.0.0", None),
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(removed, managed_boxes, "1.0.0", None),
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// Allows use of unary negate on unsigned integers, e.g. -e for e: u8
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(removed, negate_unsigned, "1.0.0", Some(29645)),
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// A way to temporarily opt out of opt in copy. This will *never* be accepted.
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(removed, opt_out_copy, "1.0.0", None),
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(removed, quad_precision_float, "1.0.0", None),
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(removed, struct_inherit, "1.0.0", None),
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(removed, test_removed_feature, "1.0.0", None),
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(removed, visible_private_types, "1.0.0", None)
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);
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declare_features! (
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(accepted, associated_types, "1.0.0", None),
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// allow overloading augmented assignment operations like `a += b`
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(accepted, augmented_assignments, "1.8.0", Some(28235)),
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// allow empty structs and enum variants with braces
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(accepted, braced_empty_structs, "1.8.0", Some(29720)),
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(accepted, default_type_params, "1.0.0", None),
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(accepted, globs, "1.0.0", None),
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(accepted, if_let, "1.0.0", None),
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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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(accepted, issue_5723_bootstrap, "1.0.0", None),
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(accepted, macro_rules, "1.0.0", None),
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// Allows using #![no_std]
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(accepted, no_std, "1.0.0", None),
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(accepted, slicing_syntax, "1.0.0", None),
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(accepted, struct_variant, "1.0.0", None),
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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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(accepted, test_accepted_feature, "1.0.0", None),
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(accepted, tuple_indexing, "1.0.0", None),
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(accepted, while_let, "1.0.0", None),
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// Allows `#[deprecated]` attribute
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(accepted, deprecated, "1.9.0", Some(29935))
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);
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// (changing above list without updating src/doc/reference.md makes @cmr sad)
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#[derive(PartialEq, Copy, Clone, Debug)]
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pub enum AttributeType {
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/// Normal, builtin attribute that is consumed
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/// by the compiler before the unused_attribute check
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Normal,
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/// Builtin attribute that may not be consumed by the compiler
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/// before the unused_attribute check. These attributes
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/// will be ignored by the unused_attribute lint
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Whitelisted,
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/// Builtin attribute that is only allowed at the crate level
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CrateLevel,
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}
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pub enum AttributeGate {
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/// Is gated by a given feature gate, reason
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/// and function to check if enabled
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Gated(&'static str, &'static str, fn(&Features) -> bool),
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/// Ungated attribute, can be used on all release channels
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Ungated,
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}
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// fn() is not Debug
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impl ::std::fmt::Debug for AttributeGate {
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fn fmt(&self, fmt: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
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match *self {
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Gated(ref name, ref expl, _) => write!(fmt, "Gated({}, {})", name, expl),
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Ungated => write!(fmt, "Ungated")
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}
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}
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}
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macro_rules! cfg_fn {
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($field: ident) => {{
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fn f(features: &Features) -> bool {
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features.$field
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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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// 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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// RFC #1445.
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("structural_match", Whitelisted, Gated("structural_match",
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"the semantics of constant patterns is \
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not yet settled",
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cfg_fn!(structural_match))),
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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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cfg_fn!(plugin))),
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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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cfg_fn!(no_core))),
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("lang", Normal, Gated("lang_items",
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"language items are subject to change",
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cfg_fn!(lang_items))),
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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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cfg_fn!(linkage))),
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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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cfg_fn!(thread_local))),
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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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cfg_fn!(on_unimplemented))),
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("allocator", Whitelisted, Gated("allocator",
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"the `#[allocator]` attribute is an experimental feature",
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cfg_fn!(allocator))),
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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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cfg_fn!(needs_allocator))),
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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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cfg_fn!(rustc_attrs))),
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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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cfg_fn!(rustc_attrs))),
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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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cfg_fn!(rustc_attrs))),
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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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cfg_fn!(rustc_attrs))),
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("rustc_dirty", Whitelisted, Gated("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("rustc_attrs",
|
|
"the `#[rustc_clean]` attribute \
|
|
is just used for rustc unit tests \
|
|
and will never be stable",
|
|
cfg_fn!(rustc_attrs))),
|
|
("rustc_symbol_name", Whitelisted, Gated("rustc_attrs",
|
|
"internal rustc attributes will never be stable",
|
|
cfg_fn!(rustc_attrs))),
|
|
("rustc_item_path", Whitelisted, Gated("rustc_attrs",
|
|
"internal rustc attributes will never be stable",
|
|
cfg_fn!(rustc_attrs))),
|
|
("rustc_move_fragments", Normal, Gated("rustc_attrs",
|
|
"the `#[rustc_move_fragments]` attribute \
|
|
is just used for rustc unit tests \
|
|
and will never be stable",
|
|
cfg_fn!(rustc_attrs))),
|
|
("rustc_mir", Whitelisted, Gated("rustc_attrs",
|
|
"the `#[rustc_mir]` attribute \
|
|
is just used for rustc unit tests \
|
|
and will never be stable",
|
|
cfg_fn!(rustc_attrs))),
|
|
("rustc_no_mir", Whitelisted, Gated("rustc_attrs",
|
|
"the `#[rustc_no_mir]` attribute \
|
|
is just used to make tests pass \
|
|
and will never be stable",
|
|
cfg_fn!(rustc_attrs))),
|
|
|
|
("allow_internal_unstable", Normal, Gated("allow_internal_unstable",
|
|
EXPLAIN_ALLOW_INTERNAL_UNSTABLE,
|
|
cfg_fn!(allow_internal_unstable))),
|
|
|
|
("fundamental", Whitelisted, Gated("fundamental",
|
|
"the `#[fundamental]` attribute \
|
|
is an experimental feature",
|
|
cfg_fn!(fundamental))),
|
|
|
|
("linked_from", Normal, Gated("linked_from",
|
|
"the `#[linked_from]` attribute \
|
|
is an experimental feature",
|
|
cfg_fn!(linked_from))),
|
|
|
|
// 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("naked_functions",
|
|
"the `#[naked]` attribute \
|
|
is an experimental feature",
|
|
cfg_fn!(naked_functions))),
|
|
("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("no_debug",
|
|
"the `#[no_debug]` attribute \
|
|
is an experimental feature",
|
|
cfg_fn!(no_debug))),
|
|
("omit_gdb_pretty_printer_section", Whitelisted, Gated("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_no_drop_flag", Whitelisted, Gated("unsafe_no_drop_flag",
|
|
"unsafe_no_drop_flag has unstable semantics \
|
|
and may be removed in the future",
|
|
cfg_fn!(unsafe_no_drop_flag))),
|
|
("unsafe_destructor_blind_to_params",
|
|
Normal,
|
|
Gated("dropck_parametricity",
|
|
"unsafe_destructor_blind_to_params has unstable semantics \
|
|
and may be removed in the future",
|
|
cfg_fn!(dropck_parametricity))),
|
|
("unwind", Whitelisted, Gated("unwind_attributes", "#[unwind] is experimental",
|
|
cfg_fn!(unwind_attributes))),
|
|
|
|
// used in resolve
|
|
("prelude_import", Whitelisted, Gated("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("unboxed_closures",
|
|
"unboxed_closures are still evolving",
|
|
cfg_fn!(unboxed_closures))),
|
|
("rustc_reflect_like", Whitelisted, Gated("reflect",
|
|
"defining reflective traits is still evolving",
|
|
cfg_fn!(reflect))),
|
|
|
|
// 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),
|
|
];
|
|
|
|
// 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!(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)),
|
|
];
|
|
|
|
#[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);
|
|
}
|
|
}
|
|
}
|
|
|
|
struct Context<'a> {
|
|
features: &'a Features,
|
|
span_handler: &'a Handler,
|
|
cm: &'a CodeMap,
|
|
plugin_attributes: &'a [(String, AttributeType)],
|
|
}
|
|
|
|
macro_rules! gate_feature_fn {
|
|
($cx: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr) => {{
|
|
let (cx, has_feature, span, name, explain) = ($cx, $has_feature, $span, $name, $explain);
|
|
let has_feature: bool = has_feature(&$cx.features);
|
|
debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
|
|
if !has_feature && !cx.cm.span_allows_unstable(span) {
|
|
emit_feature_err(cx.span_handler, name, span, GateIssue::Language, explain);
|
|
}
|
|
}}
|
|
}
|
|
|
|
macro_rules! gate_feature {
|
|
($cx: expr, $feature: ident, $span: expr, $explain: expr) => {
|
|
gate_feature_fn!($cx, |x:&Features| x.$feature, $span, stringify!($feature), $explain)
|
|
}
|
|
}
|
|
|
|
impl<'a> Context<'a> {
|
|
fn check_attribute(&self, attr: &ast::Attribute, is_macro: bool) {
|
|
debug!("check_attribute(attr = {:?})", attr);
|
|
let name = &*attr.name();
|
|
for &(n, ty, ref gateage) in KNOWN_ATTRIBUTES {
|
|
if n == name {
|
|
if let &Gated(ref name, ref desc, ref has_feature) = gateage {
|
|
gate_feature_fn!(self, has_feature, attr.span, name, 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_") {
|
|
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 {
|
|
// 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",
|
|
name));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn check_attribute(attr: &ast::Attribute, handler: &Handler,
|
|
cm: &CodeMap, features: &Features) {
|
|
let cx = Context {
|
|
features: features, span_handler: handler,
|
|
cm: cm, plugin_attributes: &[]
|
|
};
|
|
cx.check_attribute(attr, true);
|
|
}
|
|
|
|
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 or Removed features
|
|
ACCEPTED_FEATURES.iter().chain(REMOVED_FEATURES.iter())
|
|
.find(|t| t.0 == feature)
|
|
.unwrap().2
|
|
}
|
|
}
|
|
|
|
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.help(&format!("add #![feature({})] to the \
|
|
crate attributes to enable",
|
|
feature));
|
|
err.emit();
|
|
}
|
|
|
|
const EXPLAIN_BOX_SYNTAX: &'static str =
|
|
"box expression syntax is experimental; you can call `Box::new` instead.";
|
|
|
|
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_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";
|
|
|
|
pub const EXPLAIN_DERIVE_UNDERSCORE: &'static str =
|
|
"attributes of the form `#[derive_*]` are reserved for the compiler";
|
|
|
|
pub const EXPLAIN_PLACEMENT_IN: &'static str =
|
|
"placement-in expression syntax is experimental and 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 !cx.context.cm.span_allows_unstable(span) {
|
|
gate_feature!(cx.context, $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() {
|
|
gate_feature_post!(&self, 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") {
|
|
gate_feature_post!(&self, 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") {
|
|
gate_feature_post!(&self, link_args, i.span,
|
|
"the `link_args` attribute is not portable \
|
|
across platforms, it is recommended to \
|
|
use `#[link(name = \"foo\")]` instead")
|
|
}
|
|
match foreign_module.abi {
|
|
Abi::RustIntrinsic =>
|
|
gate_feature_post!(&self, intrinsics, i.span,
|
|
"intrinsics are subject to change"),
|
|
Abi::PlatformIntrinsic => {
|
|
gate_feature_post!(&self, platform_intrinsics, i.span,
|
|
"platform intrinsics are experimental \
|
|
and possibly buggy")
|
|
},
|
|
Abi::Vectorcall => {
|
|
gate_feature_post!(&self, abi_vectorcall, i.span,
|
|
"vectorcall is experimental and subject to change")
|
|
}
|
|
_ => ()
|
|
}
|
|
}
|
|
|
|
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");
|
|
}
|
|
}
|
|
|
|
ast::ItemKind::Struct(..) => {
|
|
if attr::contains_name(&i.attrs[..], "simd") {
|
|
gate_feature_post!(&self, 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" {
|
|
gate_feature_post!(&self, repr_simd, i.span,
|
|
"SIMD types are experimental \
|
|
and possibly buggy");
|
|
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
ast::ItemKind::DefaultImpl(..) => {
|
|
gate_feature_post!(&self, optin_builtin_traits,
|
|
i.span,
|
|
"default trait implementations are experimental \
|
|
and possibly buggy");
|
|
}
|
|
|
|
ast::ItemKind::Impl(_, polarity, _, _, _, _) => {
|
|
match 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");
|
|
},
|
|
_ => {}
|
|
}
|
|
}
|
|
|
|
_ => {}
|
|
}
|
|
|
|
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 {
|
|
gate_feature_post!(&self, 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(_) => {
|
|
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::Try(..) => {
|
|
gate_feature_post!(&self, 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() => {
|
|
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::Vec(..) => {
|
|
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");
|
|
}
|
|
_ => {}
|
|
}
|
|
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, _, _) => {
|
|
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, _) if abi == Abi::RustIntrinsic => {
|
|
gate_feature_post!(&self, intrinsics,
|
|
span,
|
|
"intrinsics are subject to change")
|
|
}
|
|
FnKind::ItemFn(_, _, _, _, abi, _) |
|
|
FnKind::Method(_, &ast::MethodSig { abi, .. }, _) => match abi {
|
|
Abi::RustCall => {
|
|
gate_feature_post!(&self, unboxed_closures, span,
|
|
"rust-call ABI is subject to change");
|
|
},
|
|
Abi::Vectorcall => {
|
|
gate_feature_post!(&self, 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(..) => {
|
|
gate_feature_post!(&self, associated_consts,
|
|
ti.span,
|
|
"associated constants are experimental")
|
|
}
|
|
ast::TraitItemKind::Method(ref sig, _) => {
|
|
if sig.constness == 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: &'v ast::ImplItem) {
|
|
if ii.defaultness == ast::Defaultness::Default {
|
|
gate_feature_post!(&self, specialization,
|
|
ii.span,
|
|
"specialization is unstable");
|
|
}
|
|
|
|
match ii.node {
|
|
ast::ImplItemKind::Const(..) => {
|
|
gate_feature_post!(&self, associated_consts,
|
|
ii.span,
|
|
"associated constants are experimental")
|
|
}
|
|
ast::ImplItemKind::Method(ref sig, _) => {
|
|
if sig.constness == 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: &'v ast::Visibility) {
|
|
let span = match *vis {
|
|
ast::Visibility::Crate(span) => span,
|
|
ast::Visibility::Restricted { ref path, .. } => {
|
|
// Check for type parameters
|
|
let found_param = path.segments.iter().any(|segment| {
|
|
!segment.parameters.types().is_empty() ||
|
|
!segment.parameters.lifetimes().is_empty() ||
|
|
!segment.parameters.bindings().is_empty()
|
|
});
|
|
if found_param {
|
|
self.context.span_handler.span_err(path.span, "type or lifetime parameters \
|
|
in visibility path");
|
|
}
|
|
path.span
|
|
}
|
|
_ => return,
|
|
};
|
|
gate_feature_post!(&self, pub_restricted, span, "`pub(restricted)` syntax is experimental");
|
|
}
|
|
}
|
|
|
|
pub fn get_features(span_handler: &Handler, krate: &ast::Crate) -> Features {
|
|
let mut features = Features::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
|
|
}
|
|
};
|
|
if let Some(&(_, _, _, setter)) = ACTIVE_FEATURES.iter()
|
|
.find(|& &(n, _, _, _)| name == n) {
|
|
*(setter(&mut features)) = true;
|
|
}
|
|
else if let Some(&(_, _, _)) = REMOVED_FEATURES.iter()
|
|
.find(|& &(n, _, _)| name == n) {
|
|
span_handler.span_err(mi.span, "feature has been removed");
|
|
}
|
|
else if let Some(&(_, _, _)) = ACCEPTED_FEATURES.iter()
|
|
.find(|& &(n, _, _)| name == n) {
|
|
features.declared_stable_lang_features.push(mi.span);
|
|
} else {
|
|
features.declared_lib_features.push((name, mi.span));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
features
|
|
}
|
|
|
|
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);
|
|
let features = get_features(span_handler, krate);
|
|
{
|
|
let ctx = Context {
|
|
features: &features,
|
|
span_handler: span_handler,
|
|
cm: cm,
|
|
plugin_attributes: plugin_attributes,
|
|
};
|
|
visit::walk_crate(&mut PostExpansionVisitor { context: &ctx }, krate);
|
|
}
|
|
features
|
|
}
|
|
|
|
#[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);
|
|
}
|
|
}
|
|
}
|
|
}
|