Revert "also fully resolve predicates from the next solver"

This reverts commit cb2d69e.

Author: adwinwhite

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -328,52 +328,25 @@ fn do_normalize_predicates<'tcx>(
             .with_next_trait_solver(true)
             .ignoring_regions()
             .build(TypingMode::non_body_analysis());
-        let predicates_by_next: Vec<Option<_>> = original_predicates
-            .iter()
-            .cloned()
-            .map(|p| {
-                crate::solve::deeply_normalize::<_, ScrubbedTraitError<'tcx>>(
+        for (orig_pred, pred_by_old) in original_predicates.into_iter().zip(&predicates) {
+            let inconsistent_pred_by_next =
+                match crate::solve::deeply_normalize::<_, ScrubbedTraitError<'tcx>>(
                     infcx.at(&cause, elaborated_env),
-                    p,
-                )
-                .ok()
-            })
-            .collect();
-
-        let errors = infcx.resolve_regions(cause.body_id, elaborated_env, []);
-        if !errors.is_empty() {
-            tcx.dcx().span_delayed_bug(
-                span,
-                format!(
-                    "failed region resolution while normalizing {elaborated_env:?}: {errors:?}"
-                ),
-            );
-        }
-
-        let predicates_by_next = match infcx.fully_resolve(predicates_by_next) {
-            Ok(predicates) => predicates,
-            Err(fixup_err) => {
-                span_bug!(
-                    span,
-                    "inference variables in normalized parameter environment: {}",
-                    fixup_err
-                );
-            }
-        };
-
-        for ((orig_pred, old_pred), next_pred) in
-            original_predicates.iter().zip(&predicates).zip(&predicates_by_next)
-        {
-            if let Some(next_pred) = next_pred
-                && next_pred == old_pred
-            {
-                continue;
-            }
+                    orig_pred,
+                ) {
+                    Ok(pred_by_next) => {
+                        if pred_by_next == *pred_by_old {
+                            continue;
+                        }
+                        Some(pred_by_next)
+                    }
+                    Err(_) => None,
+                };
             tcx.dcx().span_err(
                 span,
                 format!(
                     "inconsistency during normalizing env `{:#?}`, old={:#?}, next={:#?}",
-                    orig_pred, old_pred, next_pred
+                    orig_pred, pred_by_old, inconsistent_pred_by_next
                 ),
             );
         }