Add regression test for passing a pointer to a struct. (#988)

Closes #351.

test/NVQPP/struct_arg.cpp

@@ -0,0 +1,37 @@
+/*******************************************************************************
+ * Copyright (c) 2022 - 2023 NVIDIA Corporation & Affiliates.                  *
+ * All rights reserved.                                                        *
+ *                                                                             *
+ * This source code and the accompanying materials are made available under    *
+ * the terms of the Apache License 2.0 which accompanies this distribution.    *
+ ******************************************************************************/
+
+// RUN: nvq++ --enable-mlir --emit-qir %s && cat struct_arg.qir.ll | \
+// RUN: FileCheck %s ; rm struct_arg.qir.ll
+
+#include <cudaq.h>
+#include <iostream>
+
+struct baz {
+  void operator()(cudaq::qubit &q) __qpu__ { x(q); }
+};
+
+struct foo {
+  template <typename CallableKernel>
+  void operator()(CallableKernel &&func, int n) __qpu__ {
+    cudaq::qreg q(n);
+    func(q[0]);
+    mz(q[0]);
+  }
+};
+
+// CHECK-LABEL: define void @_ZN3fooclI3bazEEvOT_i
+// CHECK-SAME: (i8* nocapture readnone %{{.*}}, {}* nocapture readnone %{{.*}}, i32 %{{.*}})
+
+int main() {
+  auto result = cudaq::sample(1000, foo{}, baz{}, 1);
+  for (auto &&[bits, counts] : result) {
+    std::cout << bits << " : " << counts << '\n';
+  }
+  return 0;
+}