1 files changed, 13 insertions, 12 deletions
diff --git a/compiler/rustc_middle/src/middle/mod.rs b/compiler/rustc_middle/src/middle/mod.rs
index 85c5af9ca..8c1b1ff12 100644
--- a/compiler/rustc_middle/src/middle/mod.rs
+++ b/compiler/rustc_middle/src/middle/mod.rs
@@ -7,22 +7,23 @@ pub mod lib_features {
     use rustc_data_structures::fx::FxHashMap;
     use rustc_span::{symbol::Symbol, Span};
 
-    #[derive(HashStable, Debug)]
+    #[derive(Copy, Clone, Debug, PartialEq, Eq)]
+    #[derive(HashStable, TyEncodable, TyDecodable)]
+    pub enum FeatureStability {
+        AcceptedSince(Symbol),
+        Unstable,
+    }
+
+    #[derive(HashStable, Debug, Default)]
     pub struct LibFeatures {
-        /// A map from feature to stabilisation version.
-        pub stable: FxHashMap<Symbol, (Symbol, Span)>,
-        pub unstable: FxHashMap<Symbol, Span>,
+        pub stability: FxHashMap<Symbol, (FeatureStability, Span)>,
     }
 
     impl LibFeatures {
-        pub fn to_vec(&self) -> Vec<(Symbol, Option<Symbol>)> {
-            let mut all_features: Vec<_> = self
-                .stable
-                .iter()
-                .map(|(f, (s, _))| (*f, Some(*s)))
-                .chain(self.unstable.keys().map(|f| (*f, None)))
-                .collect();
-            all_features.sort_unstable_by(|a, b| a.0.as_str().partial_cmp(b.0.as_str()).unwrap());
+        pub fn to_vec(&self) -> Vec<(Symbol, FeatureStability)> {
+            let mut all_features: Vec<_> =
+                self.stability.iter().map(|(&sym, &(stab, _))| (sym, stab)).collect();
+            all_features.sort_unstable_by(|(a, _), (b, _)| a.as_str().cmp(b.as_str()));
             all_features
         }
     }