Don't allow dllimport variables in constant initializers

This is a follow-up to David's r211677. For the following code,
we would end up referring to 'foo' in the initializer for 'arr',
and then fail to link, because 'foo' is dllimport and needs to be
accessed through the __imp_?foo.

  __declspec(dllimport) extern const char foo[];
  const char* f() {
    static const char* const arr[] = { foo };
    return arr[0];
  }

Differential Revision: http://reviews.llvm.org/D4299

llvm-svn: 211736
diff --git a/clang/test/CodeGenCXX/dllimport.cpp b/clang/test/CodeGenCXX/dllimport.cpp
index 63b1192..d15eea2 100644
--- a/clang/test/CodeGenCXX/dllimport.cpp
+++ b/clang/test/CodeGenCXX/dllimport.cpp
@@ -94,6 +94,14 @@
 };
 USE(inlineStaticLocalsFunc);
 
+// The address of a dllimport global cannot be used in constant initialization.
+// M32-DAG: @"\01?arr@?0??initializationFunc@@YAPAHXZ@4QBQAHB" = internal global [1 x i32*] zeroinitializer
+// GNU-DAG: @_ZZ18initializationFuncvE3arr = internal global [1 x i32*] zeroinitializer
+int *initializationFunc() {
+  static int *const arr[] = {&ExternGlobalDecl};
+  return arr[0];
+}
+USE(initializationFunc);
 
 
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