Move the set of features to the features query.

compiler/rustc_expand/src/config.rs

@@ -167,6 +167,7 @@ fn active_features_up_to(edition: Edition) -> impl Iterator<Item = &'static Feat
             if let Some(Feature { since, .. }) = ACCEPTED_FEATURES.iter().find(|f| name == f.name) {
                 let since = Some(Symbol::intern(since));
                 features.declared_lang_features.push((name, mi.span(), since));
+                features.active_features.insert(name);
                 continue;
             }
 
@@ -187,10 +188,12 @@ fn active_features_up_to(edition: Edition) -> impl Iterator<Item = &'static Feat
             if let Some(f) = ACTIVE_FEATURES.iter().find(|f| name == f.name) {
                 f.set(&mut features, mi.span());
                 features.declared_lang_features.push((name, mi.span(), None));
+                features.active_features.insert(name);
                 continue;
             }
 
             features.declared_lib_features.push((name, mi.span()));
+            features.active_features.insert(name);
         }
     }
 

compiler/rustc_feature/src/active.rs

@@ -2,6 +2,7 @@
 
 use super::{to_nonzero, Feature, State};
 
+use rustc_data_structures::fx::FxHashSet;
 use rustc_span::edition::Edition;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::Span;
@@ -47,6 +48,8 @@ pub struct Features {
             pub declared_lang_features: Vec<(Symbol, Span, Option<Symbol>)>,
             /// `#![feature]` attrs for non-language (library) features.
             pub declared_lib_features: Vec<(Symbol, Span)>,
+            /// Features enabled for this crate.
+            pub active_features: FxHashSet<Symbol>,
             $(
                 $(#[doc = $doc])*
                 pub $feature: bool
@@ -58,6 +61,11 @@ pub fn walk_feature_fields(&self, mut f: impl FnMut(&str, bool)) {
                 $(f(stringify!($feature), self.$feature);)+
             }
 
+            /// Is the given feature active?
+            pub fn active(&self, feature: Symbol) -> bool {
+                self.active_features.contains(&feature)
+            }
+
             /// Is the given feature enabled?
             ///
             /// Panics if the symbol doesn't correspond to a declared feature.

compiler/rustc_middle/src/middle/stability.rs

@@ -6,7 +6,7 @@
 use crate::ty::{self, DefIdTree, TyCtxt};
 use rustc_ast::NodeId;
 use rustc_attr::{self as attr, ConstStability, Deprecation, Stability};
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{Applicability, Diagnostic};
 use rustc_feature::GateIssue;
 use rustc_hir as hir;
@@ -66,9 +66,6 @@ pub struct Index {
 
     /// Maps for each crate whether it is part of the staged API.
     pub staged_api: FxHashMap<CrateNum, bool>,
-
-    /// Features enabled for this crate.
-    pub active_features: FxHashSet<Symbol>,
 }
 
 impl Index {
@@ -423,7 +420,7 @@ pub fn eval_stability(
                     debug!("stability: skipping span={:?} since it is internal", span);
                     return EvalResult::Allow;
                 }
-                if self.stability().active_features.contains(&feature) {
+                if self.features().active(feature) {
                     return EvalResult::Allow;
                 }
 

compiler/rustc_passes/src/stability.rs

@@ -663,19 +663,8 @@ fn stability_index(tcx: TyCtxt<'_>, (): ()) -> Index {
         stab_map: Default::default(),
         const_stab_map: Default::default(),
         depr_map: Default::default(),
-        active_features: Default::default(),
     };
 
-    let active_lib_features = &tcx.features().declared_lib_features;
-    let active_lang_features = &tcx.features().declared_lang_features;
-
-    // Put the active features into a map for quick lookup.
-    index.active_features = active_lib_features
-        .iter()
-        .map(|&(s, ..)| s)
-        .chain(active_lang_features.iter().map(|&(s, ..)| s))
-        .collect();
-
     {
         let mut annotator = Annotator {
             tcx,