Stop using translate_args in the new solver

tests/ui/specialization/source-impl-requires-constraining-predicates.rs

@@ -0,0 +1,24 @@
+//@ check-pass
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
+// Tests that rebasing from the concrete impl to the default impl also processes the
+// `[u32; 0]: IntoIterator<Item = ?U>` predicate to constrain the `?U` impl arg.
+
+#![feature(specialization)]
+//~^ WARN the feature `specialization` is incomplete
+
+trait Spec {
+    type Assoc;
+}
+
+default impl<T, U> Spec for T where T: IntoIterator<Item = U> {
+    type Assoc = U;
+}
+
+impl<T> Spec for [T; 0] {}
+
+fn main() {
+    let x: <[u32; 0] as Spec>::Assoc = 1;
+}