diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -3204,7 +3204,11 @@
 }
 void CXXNameMangler::mangleType(const DependentSizedArrayType *T) {
   Out << 'A';
-  mangleExpression(T->getSizeExpr());
+  // A DependentSizedArrayType might not have size expression as below
+  // 
+  //   template<int ...N> int arr[] = {N...};
+  if (T->getSizeExpr())
+    mangleExpression(T->getSizeExpr());
   Out << '_';
   mangleType(T->getElementType());
 }
diff --git a/clang/test/AST/ast-dump-array-json.cpp b/clang/test/AST/ast-dump-array-json.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/AST/ast-dump-array-json.cpp
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -ast-dump=json -ast-dump-filter Test %s | FileCheck %s
+
+template<unsigned... N> struct A { static const int Test[]; };
+template<unsigned... N> const int A<N...>::Test[] = { N... };
+
+// CHECK: "mangledName": "_ZN1A4TestE",
+// CHECK: "mangledName": "_ZN1A4TestE",