Rollup merge of #108764 - cjgillot:dpm-adapt, r=compiler-errors

Tweaks to -Zdrop-tracking-mir

Split from https://github.com/rust-lang/rust/pull/107421

3 commits: 1 diagnostic improvement and 2 ICEs.

compiler/rustc_trait_selection/src/solve/fulfill.rs

@@ -149,6 +149,6 @@ impl<'tcx> TraitEngine<'tcx> for FulfillmentCtxt<'tcx> {
         &mut self,
         _: &InferCtxt<'tcx>,
     ) -> Vec<PredicateObligation<'tcx>> {
-        unimplemented!()
+        std::mem::take(&mut self.obligations)
     }
 }