dont discard overflow from normalizes-to goals

tests/ui/traits/next-solver/overflow/recursion-limit-normalizes-to-constraints.rs

@@ -0,0 +1,25 @@
+// compile-flags: -Znext-solver=coherence
+// check-pass
+
+// A regression test for trait-system-refactor-initiative#70.
+
+trait Trait {
+    type Assoc;
+}
+
+struct W<T: ?Sized>(*mut T);
+impl<T: ?Sized> Trait for W<W<T>>
+where
+    W<T>: Trait,
+{
+    type Assoc = ();
+}
+
+trait NoOverlap {}
+impl<T: Trait<Assoc = u32>> NoOverlap for T {}
+// `Projection(<W<_> as Trait>::Assoc, u32)` should result in error even
+// though applying the impl results in overflow. This is necessary to match
+// the behavior of the old solver.
+impl<T: ?Sized> NoOverlap for W<T> {}
+
+fn main() {}