Complete compute_unstable_feature_goal

Author: tiif

compiler/rustc_middle/src/ty/context.rs

@@ -818,6 +818,10 @@ impl<'tcx> rustc_type_ir::inherent::Features<TyCtxt<'tcx>> for &'tcx rustc_featu
     fn impl_stability(self) -> bool {
         self.impl_stability()
     }
+
+    fn enabled(self, symbol: <TyCtxt<'tcx> as Interner>::Symbol) -> bool {
+        self.enabled(symbol)
+    }
 }
 
 impl<'tcx> rustc_type_ir::inherent::Span<TyCtxt<'tcx>> for Span {

compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs

@@ -530,7 +530,7 @@ where
                 }
                 ty::PredicateKind::Clause(ty::ClauseKind::UnstableFeature(symbol)) => {
                     self.compute_unstable_feature_goal(param_env, symbol)
-                },
+                }
                 ty::PredicateKind::Subtype(predicate) => {
                     self.compute_subtype_goal(Goal { param_env, predicate })
                 }

compiler/rustc_next_trait_solver/src/solve/mod.rs

@@ -146,27 +146,41 @@ where
             None => self.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS),
         }
     }
-    
-    fn compute_unstable_feature_goal(&mut self, param_env: <I as Interner>::ParamEnv, symbol: <I as Interner>::Symbol) -> QueryResult<I> {
-        // Iterate through all goals in param_env to find the one that has the same 
-        // symbol as the one in the goal
+
+    fn compute_unstable_feature_goal(
+        &mut self,
+        param_env: <I as Interner>::ParamEnv,
+        symbol: <I as Interner>::Symbol,
+    ) -> QueryResult<I> {
+        // Iterate through all goals in param_env to find the one that has the same symbol.
         for pred in param_env.caller_bounds().iter() {
             match pred.kind().skip_binder() {
                 ty::ClauseKind::UnstableFeature(sym) => {
                     if sym == symbol {
-                        return self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes);
+                        return self
+                            .evaluate_added_goals_and_make_canonical_response(Certainty::Yes);
                     }
                 }
                 _ => {} // don't care
             }
         }
 
         if self.cx().features().impl_stability() {
-            return self.evaluate_added_goals_and_make_canonical_response(Certainty::Maybe(MaybeCause::Ambiguity));
+            return self.evaluate_added_goals_and_make_canonical_response(Certainty::Maybe(
+                MaybeCause::Ambiguity,
+            ));
         } else {
-            todo!();
+            // 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)
+            {
+                return self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes);
+            } else {
+                return self.evaluate_added_goals_and_make_canonical_response(Certainty::Maybe(
+                    MaybeCause::Ambiguity,
+                ));
+            }
         }
-
     }
 
     #[instrument(level = "trace", skip(self))]

compiler/rustc_type_ir/src/inherent.rs

@@ -572,6 +572,8 @@ pub trait Features<I: Interner>: Copy {
     fn associated_const_equality(self) -> bool;
 
     fn impl_stability(self) -> bool;
+
+    fn enabled(self, symbol: I::Symbol) -> bool;
 }
 
 pub trait DefId<I: Interner>: Copy + Debug + Hash + Eq + TypeFoldable<I> {