Revert "Auto merge of #101862 - cjgillot:lint-regression, r=oli-obk"

This reverts commit bc7b17cfe3, reversing
changes made to 5253b0a0a1.

compiler/rustc_middle/src/lint.rs

@@ -126,7 +126,7 @@ impl ShallowLintLevelMap {
             return (Some(level), src);
         }
 
-        for parent in tcx.hir().parent_id_iter(start) {
+        for (parent, _) in tcx.hir().parent_iter(start) {
             let specs = tcx.shallow_lint_levels_on(parent);
             if let Some(&(level, src)) = specs.specs.get(&id) {
                 return (Some(level), src);