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Auto merge of #131321 - RalfJung:feature-activation, r=nnethercote

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terminology: #[feature] *enables* a feature (instead of "declaring" or "activating" it)

Mostly, we currently call a feature that has a corresponding `#[feature(name)]` attribute in the current crate a "declared" feature. I think that is confusing as it does not align with what "declaring" usually means. Furthermore, we *also* refer to `#[stable]`/`#[unstable]` as *declaring* a feature (e.g. in [these diagnostics](f25e5abea2/compiler/rustc_passes/messages.ftl (L297-L301))), which aligns better with what "declaring" usually means. To make things worse, the functions  `tcx.features().active(...)` and  `tcx.features().declared(...)` both exist and they are doing almost the same thing (testing whether a corresponding `#[feature(name)]`  exists) except that `active` would ICE if the feature is not an unstable lang feature. On top of this, the callback when a feature is activated/declared is called `set_enabled`, and many comments also talk about "enabling" a feature.

So really, our terminology is just a mess.

I would suggest we use "declaring a feature" for saying that something is/was guarded by a feature (e.g. `#[stable]`/`#[unstable]`), and "enabling a feature" for  `#[feature(name)]`. This PR implements that.
This commit is contained in:
bors 2024-10-22 11:02:35 +00:00
commit bca5fdebe0
21 changed files with 153 additions and 131 deletions
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4
compiler/rustc_lint/src/builtin.rs
View file

@ -2288,10 +2288,10 @@ impl EarlyLintPass for IncompleteInternalFeatures {
fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
let features = cx.builder.features();
features
.declared_lang_features
.enabled_lang_features()
.iter()
.map(|(name, span, _)| (name, span))
.chain(features.declared_lib_features.iter().map(|(name, span)| (name, span)))
.chain(features.enabled_lib_features().iter().map(|(name, span)| (name, span)))
.filter(|(&name, _)| features.incomplete(name) || features.internal(name))
.for_each(|(&name, &span)| {
if features.incomplete(name) {

2
compiler/rustc_lint/src/levels.rs
View file

@ -858,7 +858,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
#[track_caller]
fn check_gated_lint(&self, lint_id: LintId, span: Span, lint_from_cli: bool) -> bool {
let feature = if let Some(feature) = lint_id.lint.feature_gate
&& !self.features.active(feature)
&& !self.features.enabled(feature)
{
// Lint is behind a feature that is not enabled; eventually return false.
feature