make the eval() functions on our const types return the resulting value

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -288,7 +288,7 @@ pub fn normalize_param_env_or_error<'tcx>(
                     // should actually be okay since without `feature(generic_const_exprs)` the only
                     // const arguments that have a non-empty param env are array repeat counts. These
                     // do not appear in the type system though.
-                    c.eval(self.0, ty::ParamEnv::empty())
+                    c.normalize(self.0, ty::ParamEnv::empty())
                 }
             }