clang-format: C++ attribute specifiers

I have been unable to find a way to set formatting for C++ attribute
specifiers using clang format.

Here is an example of the desired output:

  [[deprecated("Reason for...")]]
  void foo();

I suspect this is simply a missing feature, at the moment.

I rely heavily on clang-format to enforce my style guide. Any help or
workaround would be greatly appreciated.

Thank you.

Jacques Nel