diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
index 892808386deef..13c325a14e402 100644
--- a/compiler/rustc_middle/src/mir/mono.rs
+++ b/compiler/rustc_middle/src/mir/mono.rs
@@ -7,6 +7,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc_hir::ItemId;
+use rustc_index::vec::Idx;
 use rustc_query_system::ich::{NodeIdHashingMode, StableHashingContext};
 use rustc_session::config::OptLevel;
 use rustc_span::source_map::Span;
@@ -380,7 +381,7 @@ impl<'tcx> CodegenUnit<'tcx> {
                             // instances into account. The others don't matter for
                             // the codegen tests and can even make item order
                             // unstable.
-                            InstanceDef::Item(def) => Some(def.did.index.as_usize()),
+                            InstanceDef::Item(def) => def.did.as_local().map(Idx::index),
                             InstanceDef::VtableShim(..)
                             | InstanceDef::ReifyShim(..)
                             | InstanceDef::Intrinsic(..)
@@ -391,10 +392,8 @@ impl<'tcx> CodegenUnit<'tcx> {
                             | InstanceDef::CloneShim(..) => None,
                         }
                     }
-                    MonoItem::Static(def_id) => Some(def_id.index.as_usize()),
-                    MonoItem::GlobalAsm(item_id) => {
-                        Some(item_id.def_id.to_def_id().index.as_usize())
-                    }
+                    MonoItem::Static(def_id) => def_id.as_local().map(Idx::index),
+                    MonoItem::GlobalAsm(item_id) => Some(item_id.def_id.index()),
                 },
                 item.symbol_name(tcx),
             )
diff --git a/src/test/codegen/debuginfo-generic-closure-env-names.rs b/src/test/codegen/debuginfo-generic-closure-env-names.rs
index ad59f740b567f..b29f8b4a029d0 100644
--- a/src/test/codegen/debuginfo-generic-closure-env-names.rs
+++ b/src/test/codegen/debuginfo-generic-closure-env-names.rs
@@ -3,7 +3,7 @@
 // of the enclosing functions don't get lost.
 //
 // Unfortunately, the order that debuginfo gets emitted into LLVM IR becomes a bit hard
-// to predict once async fns are involved.
+// to predict once async fns are involved, so DAG allows any order.
 //
 // Note that the test does not check async-fns when targeting MSVC because debuginfo for
 // those does not follow the enum-fallback encoding yet and thus is incomplete.
@@ -27,24 +27,24 @@
 // CHECK: ![[generic_async_block_NAMESPACE:[0-9]+]] = !DINamespace(name: "generic_async_block"
 
 // function_containing_closure<u32>()
-// NONMSVC: !DICompositeType(tag: DW_TAG_structure_type, name: "{closure_env#0}<u32>", scope: ![[function_containing_closure_NAMESPACE]]
-// MSVC: !DICompositeType(tag: DW_TAG_structure_type, name: "closure_env$0<u32>", scope: ![[function_containing_closure_NAMESPACE]]
+// NONMSVC-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "{closure_env#0}<u32>", scope: ![[function_containing_closure_NAMESPACE]]
+// MSVC-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "closure_env$0<u32>", scope: ![[function_containing_closure_NAMESPACE]]
 
 // generic_async_function<Foo>()
-// NONMSVC: !DICompositeType(tag: DW_TAG_structure_type, name: "{async_fn_env#0}<debuginfo_generic_closure_env_names::Foo>", scope: ![[generic_async_function_NAMESPACE]]
+// NONMSVC-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "{async_fn_env#0}<debuginfo_generic_closure_env_names::Foo>", scope: ![[generic_async_function_NAMESPACE]]
 
 // generic_async_function<u32>()
-// NONMSVC: !DICompositeType(tag: DW_TAG_structure_type, name: "{async_fn_env#0}<u32>", scope: ![[generic_async_function_NAMESPACE]]
+// NONMSVC-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "{async_fn_env#0}<u32>", scope: ![[generic_async_function_NAMESPACE]]
 
 // generic_async_block<Foo>()
-// NONMSVC: !DICompositeType(tag: DW_TAG_structure_type, name: "{async_block_env#0}<debuginfo_generic_closure_env_names::Foo>", scope: ![[generic_async_block_NAMESPACE]]
+// NONMSVC-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "{async_block_env#0}<debuginfo_generic_closure_env_names::Foo>", scope: ![[generic_async_block_NAMESPACE]]
 
 // generic_async_block<u32>()
-// NONMSVC: !DICompositeType(tag: DW_TAG_structure_type, name: "{async_block_env#0}<u32>", scope: ![[generic_async_block_NAMESPACE]]
+// NONMSVC-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "{async_block_env#0}<u32>", scope: ![[generic_async_block_NAMESPACE]]
 
 // function_containing_closure<Foo>()
-// NONMSVC: !DICompositeType(tag: DW_TAG_structure_type, name: "{closure_env#0}<debuginfo_generic_closure_env_names::Foo>", scope: ![[function_containing_closure_NAMESPACE]]
-// MSVC: !DICompositeType(tag: DW_TAG_structure_type, name: "closure_env$0<debuginfo_generic_closure_env_names::Foo>", scope: ![[function_containing_closure_NAMESPACE]]
+// NONMSVC-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "{closure_env#0}<debuginfo_generic_closure_env_names::Foo>", scope: ![[function_containing_closure_NAMESPACE]]
+// MSVC-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "closure_env$0<debuginfo_generic_closure_env_names::Foo>", scope: ![[function_containing_closure_NAMESPACE]]
 
 
 #![crate_type = "lib"]