style fix

Author: tiif

compiler/rustc_next_trait_solver/src/solve/mod.rs

@@ -163,12 +163,13 @@ where
         }
 
         if self.cx().features().impl_stability() {
-            // If we are in std, and the feature is not enabled through #[unstable_feature_bound(..)]
+            // If we are in std/core, and the feature is not enabled through #[unstable_feature_bound(..)]
             return self.evaluate_added_goals_and_make_canonical_response(Certainty::Maybe(
                 MaybeCause::Ambiguity,
             ));
         } else {
-            // Check if feature is enabled at crate level with #[feature(..)] or if we are currently in codegen.
+            // Outside of std/core, check if feature is enabled at crate level with #[feature(..)]
+            // or if we are currently in codegen.
             if self.cx().features().enabled(symbol)
                 || (self.typing_mode() == TypingMode::PostAnalysis)
             {

compiler/rustc_passes/src/stability.rs

@@ -811,7 +811,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
                     // it will have no effect.
                     // See: https://github.com/rust-lang/rust/issues/55436
                     //
-                    // The exception is when there is both  #[unstable_feature_bound(..)] and
+                    // The exception is when there are both  #[unstable_feature_bound(..)] and
                     //  #![unstable(feature = "..", issue = "..")] that have the same symbol because
                     // that can effectively mark an impl as unstable.
                     //

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -839,6 +839,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 }
 
                 ty::PredicateKind::Clause(ty::ClauseKind::UnstableFeature(symbol)) => {
+                    // Iterate through all goals in param_env to find the one that has the same symbol.
                     for pred in obligation.param_env.caller_bounds().iter() {
                         if let ty::ClauseKind::UnstableFeature(sym) = pred.kind().skip_binder() {
                             if sym == symbol {

tests/ui/internal/auxiliary/unstable_feature.rs

@@ -20,7 +20,6 @@ impl Foo for Bar {
     fn foo() {}
 }
 
-
 #[unstable_feature_bound(feat_moo)]
 #[unstable(feature = "feat_moo", issue = "none" )]
 impl Foo for Moo {