Add test for disabled shadow copies in imported functions

Author: usama54321

test/Serialization/debug-value.swift

@@ -2,7 +2,13 @@
 // RUN: %{python} %utils/split_file.py -o %t %s
 
 // RUN: %target-swift-frontend -g -experimental-serialize-debug-info -emit-module -o %t/MyModule.swiftmodule %t/MyModule.swift -O
-// RUN: %target-swift-frontend -g  -I %t %t/Main.swift -experimental-serialize-debug-info -O -emit-sil -o - | %FileCheck %s
+// RUN: %target-swift-frontend -g -I %t %t/Main.swift -experimental-serialize-debug-info -emit-sil -o - | %FileCheck %s
+
+// Shadow copies should not be emitted for imported functions as the imported
+// function might be optimized which breaks the unoptimized invariant of
+// emitting shadow copies. This invocation crashes if shadow copies are not
+// disabled for imported functions
+// RUN: %target-swift-frontend -g -I %t %t/Main.swift -experimental-serialize-debug-info -o - -Onone -emit-ir
 
 // BEGIN MyModule.swift
 @_alwaysEmitIntoClient @inline(never)