Question about new warning system

[Giovanni Bajo]

Hello DJ,

I'm updating a piece of code of the C++ frontend which involves a warning,
so I was planning on adding the correct warning option to it. The original
code is the following:

      if (warn_missing_braces)
           warning (0, "missing braces around initializer");

So, what is the correct way of fixing this:

[1]
      if (warn_missing_braces)
           warning (OPT_Wmissing_braces, "missing braces around
initializer");

[2]
      if (OPT_Wmissing_braces)
           warning (OPT_Wmissing_braces, "missing braces around
initializer");

[3]
      warning (OPT_Wmissing_braces, "missing braces around initializer");

What is the difference between [1], [2], [3]?

Thanks,
-- 
Giovanni Bajo