Ensure that THIR unsafety check is done before stealing it. Fixes #11…

…1520.

compiler/rustc_mir_build/src/build/mod.rs

@@ -56,7 +56,8 @@ pub(crate) fn closure_saved_names_of_captured_variables<'tcx>(
 /// Construct the MIR for a given `DefId`.
 fn mir_build(tcx: TyCtxt<'_>, def: LocalDefId) -> Body<'_> {
     // Ensure unsafeck and abstract const building is ran before we steal the THIR.
-    tcx.ensure_with_value().thir_check_unsafety(def);
+    tcx.ensure_with_value()
+        .thir_check_unsafety(tcx.typeck_root_def_id(def.to_def_id()).expect_local());
     tcx.ensure_with_value().thir_abstract_const(def);
     if let Err(e) = tcx.check_match(def) {
         return construct_error(tcx, def, e);