Rename `ACTIVE_FEATURES` as `UNSTABLE_FEATURES`.

It's a better name, and lets "active features" refer to the features
that are active in a particular program, due to being declared or
enabled by the edition.

The commit also renames `Features::enabled` as `Features::active` to
match this; I changed my mind and have decided that "active" is a little
better thatn "enabled" for this, particularly because a number of
pre-existing comments use "active" in this way.

Finally, the commit renames `Status::Stable` as `Status::Accepted`, to
match `ACCEPTED_FEATURES`.

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 671204c0d8e..abb0ab5630c 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -39,7 +39,7 @@ pub struct GatedSpans {
 
 impl GatedSpans {
     /// Feature gate the given `span` under the given `feature`
-    /// which is same `Symbol` used in `active.rs`.
+    /// which is same `Symbol` used in `unstable.rs`.
     pub fn gate(&self, feature: Symbol, span: Span) {
         self.spans.borrow_mut().entry(feature).or_default().push(span);
     }
@@ -78,7 +78,7 @@ impl SymbolGallery {
 }
 
 /// Construct a diagnostic for a language feature error due to the given `span`.
-/// The `feature`'s `Symbol` is the one you used in `active.rs` and `rustc_span::symbols`.
+/// The `feature`'s `Symbol` is the one you used in `unstable.rs` and `rustc_span::symbols`.
 #[track_caller]
 pub fn feature_err(
     sess: &ParseSess,