Question about new warning system

[Gabriel Dos Reis]

"Giovanni Bajo" <rasky@develer.com> writes:

| 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]?

[3] shows which options is used to enable/disable that diagnostic
(assumming it is controled by a particular switch).  In either case
the main diagnostic is always emitted.

As pointed out by JSM yesterday, it is not clear whether [1] should be
preferred over [2] or the converse.  I think having two ways to
control the same diagnostic is a bit confusing.  I think the
difference between [1] and [2] is that warn_xxx can be true even
though OPT_Wxxxx  is not explicitly specified -- e.g. it could be set
as a consequence of setting another flag.  

-- Gaby