Build DebugInfo for coroutine-closure

tests/codegen/async-closure-debug.rs

@@ -0,0 +1,21 @@
+// Just make sure that async closures don't ICE.
+//
+// compile-flags: -C debuginfo=2 --edition=2018
+// ignore-msvc
+
+// CHECK-DAG:  [[GEN_FN:!.*]] = !DINamespace(name: "async_closure_test"
+// CHECK-DAG:  [[CLOSURE:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "{closure_env#0}", scope: [[GEN_FN]]
+// CHECK-DAG:  [[UPVAR:!.*]] = !DIDerivedType(tag: DW_TAG_member, name: "upvar", scope: [[CLOSURE]]
+
+#![feature(async_closure)]
+
+fn async_closure_test(upvar: &str) -> impl async Fn() + '_ {
+    async move || {
+        let hello = String::from("hello");
+        println!("{hello}, {upvar}");
+    }
+}
+
+fn main() {
+    let _async_closure = async_closure_test("world");
+}