PATCH: new flag to say when things are synthesized

[David R. Linn]

>> Agreed in principle.  Which brings the question: What exactly do we
>> name "warnings"?  This is not a rhetorical question --  I'm serious.

Possibilities

* Questionable code (i.e. erroneous code that causes a recoverable
  error)
* code that, while legal, uses a deprecated or problematic construct
* code that uses a deprecated or problematic extension

I don't think notes that document how the compiler is doing what
the user asked fall in these categories (i.e. BK's proposed
synthesization and instantiation notes).

Feel free to post this reply to the gcc list if you see fit.