Gracefully handle normalization failures in the prospective inliner cycle detector

Author: oli-obk

compiler/rustc_mir_transform/src/inline/cycle.rs

@@ -45,7 +45,10 @@ crate fn mir_callgraph_reachable<'tcx>(
     ) -> bool {
         trace!(%caller);
         for &(callee, substs) in tcx.mir_inliner_callees(caller.def) {
-            let substs = caller.subst_mir_and_normalize_erasing_regions(tcx, param_env, substs);
+            let Ok(substs) = caller.try_subst_mir_and_normalize_erasing_regions(tcx, param_env, substs) else {
+                trace!(?caller, ?param_env, ?substs, "cannot normalize, skipping");
+                continue;
+            };
             let Some(callee) = ty::Instance::resolve(tcx, param_env, callee, substs).unwrap() else {
                 trace!(?callee, "cannot resolve, skipping");
                 continue;