Rollup merge of #152444 - ShoyuVanilla:unsized-recursion-limit, r=lcnr

`-Znext-solver` Prevent committing unfulfilled unsized coercion

Fixes https://github.com/rust-lang/trait-system-refactor-initiative/issues/266

r? lcnr

compiler/rustc_trait_selection/src/solve/inspect/analyse.rs

@@ -443,9 +443,10 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
     pub(crate) fn visit_with<V: ProofTreeVisitor<'tcx>>(&self, visitor: &mut V) -> V::Result {
         if self.depth < visitor.config().max_depth {
             try_visit!(visitor.visit_goal(self));
+            V::Result::output()
+        } else {
+            visitor.on_recursion_limit()
         }
-
-        V::Result::output()
     }
 }
 
@@ -460,6 +461,10 @@ pub trait ProofTreeVisitor<'tcx> {
     }
 
     fn visit_goal(&mut self, goal: &InspectGoal<'_, 'tcx>) -> Self::Result;
+
+    fn on_recursion_limit(&mut self) -> Self::Result {
+        Self::Result::output()
+    }
 }
 
 #[extension(pub trait InferCtxtProofTreeExt<'tcx>)]