fix next_trait_solver

Author: estebank

compiler/rustc_next_trait_solver/src/lib.rs

@@ -4,7 +4,6 @@
 //! but were uplifted in the process of making the new trait solver generic.
 //! So if you got to this crate from the old solver, it's totally normal.
 
-#![feature(if_let_guard)]
 // tidy-alphabetical-start
 #![allow(rustc::direct_use_of_rustc_type_ir)]
 #![allow(rustc::usage_of_type_ir_inherent)]

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

@@ -809,15 +809,18 @@ where
     #[instrument(level = "trace", skip(self), ret)]
     pub(super) fn term_is_fully_unconstrained(&self, goal: Goal<I, ty::NormalizesTo<I>>) -> bool {
         let universe_of_term = match goal.predicate.term.kind() {
-            ty::TermKind::Ty(ty) if let ty::Infer(ty::TyVar(vid)) = ty.kind() => {
+            ty::TermKind::Ty(ty) => {
+                let ty::Infer(ty::TyVar(vid)) = ty.kind() else {
+                    return false;
+                };
                 self.delegate.universe_of_ty(vid).unwrap()
             }
-            ty::TermKind::Const(ct)
-                if let ty::ConstKind::Infer(ty::InferConst::Var(vid)) = ct.kind() =>
-            {
+            ty::TermKind::Const(ct) => {
+                let ty::ConstKind::Infer(ty::InferConst::Var(vid)) = ct.kind() else {
+                    return false;
+                };
                 self.delegate.universe_of_ct(vid).unwrap()
             }
-            _ => return false,
         };
 
         struct ContainsTermOrNotNameable<'a, D: SolverDelegate<Interner = I>, I: Interner> {