Check signature WF when lowering MIR body

1 files changed, 18 insertions, 0 deletions

diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index 04c9375b831..5df12ac4d8b 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -513,6 +513,24 @@ fn mir_drops_elaborated_and_const_checked(tcx: TyCtxt<'_>, def: LocalDefId) -> &
         body.tainted_by_errors = Some(error_reported);
     }
 
+    // Also taint the body if it's within a top-level item that is not well formed.
+    //
+    // We do this check here and not during `mir_promoted` because that may result
+    // in borrowck cycles if WF requires looking into an opaque hidden type.
+    let root = tcx.typeck_root_def_id(def.to_def_id());
+    match tcx.def_kind(root) {
+        DefKind::Fn
+        | DefKind::AssocFn
+        | DefKind::Static { .. }
+        | DefKind::Const
+        | DefKind::AssocConst => {
+            if let Err(guar) = tcx.check_well_formed(root.expect_local()) {
+                body.tainted_by_errors = Some(guar);
+            }
+        }
+        _ => {}
+    }
+
     run_analysis_to_runtime_passes(tcx, &mut body);
 
     tcx.alloc_steal_mir(body)