[Concurrency] fix async-boxed-arg to include the Sendable in type

Author: ktoso

test/DebugInfo/async-boxed-arg.swift

@@ -1,21 +1,21 @@
 // RUN: %target-swift-frontend %s -emit-ir -g -o - -parse-as-library \
-// RUN:    -module-name M -enable-experimental-concurrency | %FileCheck %s
+// RUN:    -module-name M -enable-experimental-concurrency | %FileCheck %s --dump-input always
 // REQUIRES: concurrency
 
 @available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
-extension Collection {
+extension Collection where Element: Sendable {
   public func f() async throws {
-    return await try withTaskGroup(of: Element.self) { group in
+    return try await withThrowingTaskGroup(of: Element.self) { group in
       var i = self.startIndex
       func doit() async throws {
         group.spawn { [i] in
           return self[i]
         }
       }
-      await try doit()
+      try await doit()
     }
   }
 }
 
-// CHECK: ![[BOXTY:[0-9]+]] = !DICompositeType(tag: DW_TAG_structure_type, name: "$s5IndexSlQzz_x_SlRzlXXD"
+// CHECK: ![[BOXTY:[0-9]+]] = !DICompositeType(tag: DW_TAG_structure_type, name: "$s5IndexSlQzz_x_SlRzs8Sendable7ElementSTRpzlXXD"
 // CHECK: !DILocalVariable(name: "i", arg: 3, {{.*}}type: ![[BOXTY]]