Rollup merge of #121208 - nnethercote:delayed_bug-to-bug, r=lcnr

Convert `delayed_bug`s to `bug`s.

I have a suspicion that quite a few delayed bug paths are impossible to reach, so I did an experiment.

I converted every `delayed_bug` to a `bug`, ran the full test suite, then converted back every `bug` that was hit. A surprising number were never hit.

This is too dangerous to merge. Increased coverage (fuzzing or a crater run) would likely hit more cases. But it might be useful for people to look at and think about which paths are genuinely unreachable.

r? `@ghost`

compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs

@@ -190,10 +190,9 @@ where
                 }
             }
             if !progress {
-                return Err(infcx.dcx().span_delayed_bug(
-                    span,
-                    format!("ambiguity processing {obligations:?} from {self:?}"),
-                ));
+                infcx
+                    .dcx()
+                    .span_bug(span, format!("ambiguity processing {obligations:?} from {self:?}"));
             }
         }