bjoernager/rust
bjoernager/rust
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Remove rustc_feature::State.

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`State` is used to distinguish active vs accepted vs removed features.
However, these can also be distinguished by their location, in
`ACTIVE_FEATURES`, `ACCEPTED_FEATURES`, and `REMOVED_FEATURES`.

So this commit removes `State` and moves the internals of its variants
next to the `Feature` in each element of `*_FEATURES`, introducing new
types `ActiveFeature` and `RemovedFeature`. (There is no need for
`AcceptedFeature` because `State::Accepted` had no fields.)

This is a tighter type representation, avoids the need for some runtime
checks, and makes the code a bit shorter.
This commit is contained in:
Nicholas Nethercote 2023-10-05 18:59:01 +11:00
parent 64368d0279
commit 41b6899487
5 changed files with 61 additions and 97 deletions
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48
compiler/rustc_expand/src/config.rs
View file

@ -14,12 +14,12 @@ use rustc_ast::{self as ast, AttrStyle, Attribute, HasAttrs, HasTokens, MetaItem
use rustc_attr as attr;
use rustc_data_structures::flat_map_in_place::FlatMapInPlace;
use rustc_data_structures::fx::FxHashSet;
use rustc_feature::{Feature, Features, State as FeatureState};
use rustc_feature::Features;
use rustc_feature::{ACCEPTED_FEATURES, ACTIVE_FEATURES, REMOVED_FEATURES};
use rustc_parse::validate_attr;
use rustc_session::parse::feature_err;
use rustc_session::Session;
use rustc_span::edition::{Edition, ALL_EDITIONS};
use rustc_span::edition::ALL_EDITIONS;
use rustc_span::symbol::{sym, Symbol};
use rustc_span::Span;
use thin_vec::ThinVec;
@ -36,16 +36,6 @@ pub struct StripUnconfigured<'a> {
}
pub fn features(sess: &Session, krate_attrs: &[Attribute]) -> Features {
fn active_features_up_to(edition: Edition) -> impl Iterator<Item = &'static Feature> {
ACTIVE_FEATURES.iter().filter(move |feature| {
if let Some(feature_edition) = feature.edition {
feature_edition <= edition
} else {
false
}
})
}
fn feature_list(attr: &Attribute) -> ThinVec<ast::NestedMetaItem> {
if attr.has_name(sym::feature)
&& let Some(list) = attr.meta_item_list()
@ -83,11 +73,13 @@ pub fn features(sess: &Session, krate_attrs: &[Attribute]) -> Features {
// Enable edition-dependent features based on `features_edition`.
// - E.g. enable `test_2018_feature` if `features_edition` is 2018 or higher
let mut edition_enabled_features = FxHashSet::default();
for feature in active_features_up_to(features_edition) {
// FIXME(Manishearth) there is currently no way to set lib features by
// edition.
edition_enabled_features.insert(feature.name);
feature.set(&mut features);
for f in ACTIVE_FEATURES {
if let Some(edition) = f.feature.edition && edition <= features_edition {
// FIXME(Manishearth) there is currently no way to set lib features by
// edition.
edition_enabled_features.insert(f.feature.name);
(f.set_enabled)(&mut features);
}
}
// Process all features declared in the code.
@ -147,19 +139,17 @@ pub fn features(sess: &Session, krate_attrs: &[Attribute]) -> Features {
}
// If the declared feature has been removed, issue an error.
if let Some(Feature { state, .. }) = REMOVED_FEATURES.iter().find(|f| name == f.name) {
if let FeatureState::Removed { reason } = state {
sess.emit_err(FeatureRemoved {
span: mi.span(),
reason: reason.map(|reason| FeatureRemovedReason { reason }),
});
continue;
}
if let Some(f) = REMOVED_FEATURES.iter().find(|f| name == f.feature.name) {
sess.emit_err(FeatureRemoved {
span: mi.span(),
reason: f.reason.map(|reason| FeatureRemovedReason { reason }),
});
continue;
}
// If the declared feature is stable, record it.
if let Some(Feature { since, .. }) = ACCEPTED_FEATURES.iter().find(|f| name == f.name) {
let since = Some(Symbol::intern(since));
if let Some(f) = ACCEPTED_FEATURES.iter().find(|f| name == f.name) {
let since = Some(Symbol::intern(f.since));
features.set_declared_lang_feature(name, mi.span(), since);
continue;
}
@ -175,8 +165,8 @@ pub fn features(sess: &Session, krate_attrs: &[Attribute]) -> Features {
}
// If the declared feature is unstable, record it.
if let Some(f) = ACTIVE_FEATURES.iter().find(|f| name == f.name) {
f.set(&mut features);
if let Some(f) = ACTIVE_FEATURES.iter().find(|f| name == f.feature.name) {
(f.set_enabled)(&mut features);
features.set_declared_lang_feature(name, mi.span(), None);
continue;
}