Only enable new solver if GCE

Author: compiler-errors

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -636,7 +636,7 @@ fn check_incompatible_features(sess: &Session, features: &Features) {
 }
 
 fn check_new_solver_banned_features(sess: &Session, features: &Features) {
-    if !sess.opts.unstable_opts.next_solver.globally {
+    if !sess.opts.unstable_opts.next_solver.globally && false {
         return;
     }
 

compiler/rustc_middle/src/ty/context.rs

@@ -3335,7 +3335,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     pub fn next_trait_solver_globally(self) -> bool {
-        self.sess.opts.unstable_opts.next_solver.globally
+        self.sess.opts.unstable_opts.next_solver.globally && !self.features().generic_const_exprs()
     }
 
     pub fn next_trait_solver_in_coherence(self) -> bool {