2018-11-26 20:59:49 -06:00
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//! # Feature gating
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2013-10-02 20:10:16 -05:00
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//!
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2015-04-16 02:18:29 -05:00
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//! This module implements the gating necessary for preventing certain compiler
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2013-10-02 20:10:16 -05:00
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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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2014-06-22 12:29:42 -05:00
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//! `#![feature(...)]` with a comma-separated list of features.
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2015-01-14 21:27:45 -06:00
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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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2015-02-03 16:31:06 -06:00
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2019-08-20 11:40:53 -05:00
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mod accepted;
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2019-08-20 11:41:18 -05:00
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mod removed;
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2019-08-20 11:50:33 -05:00
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mod active;
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2019-11-29 19:34:18 -06:00
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mod builtin_attrs;
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2019-08-22 16:48:08 -05:00
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2019-11-11 11:33:30 -06:00
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use std::fmt;
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use std::num::NonZeroU32;
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2019-11-29 17:23:38 -06:00
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use syntax_pos::{Span, edition::Edition, symbol::Symbol};
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2019-08-24 10:50:21 -05:00
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#[derive(Clone, Copy)]
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pub enum State {
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Accepted,
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Active { set: fn(&mut Features, Span) },
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Removed { reason: Option<&'static str> },
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Stabilized { reason: Option<&'static str> },
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}
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impl fmt::Debug for State {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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match self {
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State::Accepted { .. } => write!(f, "accepted"),
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State::Active { .. } => write!(f, "active"),
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State::Removed { .. } => write!(f, "removed"),
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State::Stabilized { .. } => write!(f, "stabilized"),
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}
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}
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}
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#[derive(Debug, Clone)]
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pub struct Feature {
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2019-11-29 17:23:38 -06:00
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pub state: State,
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pub name: Symbol,
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pub since: &'static str,
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2019-11-11 11:33:30 -06:00
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issue: Option<u32>, // FIXME: once #58732 is done make this an Option<NonZeroU32>
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2019-11-29 17:23:38 -06:00
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pub edition: Option<Edition>,
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2019-08-24 10:50:21 -05:00
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description: &'static str,
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}
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2019-11-11 11:33:30 -06:00
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impl Feature {
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2019-11-29 17:23:38 -06:00
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// FIXME(Centril): privatize again.
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pub fn issue(&self) -> Option<NonZeroU32> {
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2019-11-11 11:33:30 -06:00
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self.issue.and_then(|i| NonZeroU32::new(i))
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}
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}
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2019-11-29 17:39:51 -06:00
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#[derive(Copy, Clone, Debug)]
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pub enum Stability {
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Unstable,
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// First argument is tracking issue link; second argument is an optional
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// help message, which defaults to "remove this attribute".
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Deprecated(&'static str, Option<&'static str>),
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}
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2019-11-29 17:23:38 -06:00
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pub use accepted::ACCEPTED_FEATURES;
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pub use active::{ACTIVE_FEATURES, Features, INCOMPLETE_FEATURES};
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pub use removed::{REMOVED_FEATURES, STABLE_REMOVED_FEATURES};
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2019-11-29 19:34:18 -06:00
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pub use builtin_attrs::{
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AttributeGate, AttributeTemplate, AttributeType, find_gated_cfg, GatedCfg,
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BuiltinAttribute, BUILTIN_ATTRIBUTES, BUILTIN_ATTRIBUTE_MAP,
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deprecated_attributes, is_builtin_attr_name,
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};
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