Auto merge of #149657 - Kobzol:revert-149147, r=<try>

Revert "Rollup merge of #149147 - chenyukang:yukang-fix-unused_assignments-macro-gen-147648, r=JonathanBrouwer"

Author: rust-bors[bot]

compiler/rustc_mir_transform/src/liveness.rs

@@ -75,11 +75,6 @@ pub(crate) fn check_liveness<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Den
         return DenseBitSet::new_empty(0);
     }
 
-    // Don't run unused pass for items generated by foreign macros
-    if tcx.def_span(parent).in_external_macro(tcx.sess.source_map()) {
-        return DenseBitSet::new_empty(0);
-    }
-
     let mut body = &*tcx.mir_promoted(def_id).0.borrow();
     let mut body_mem;