[C++] warn_synth considered obsolete

[Mark Mitchell]

Gabriel Dos Reis wrote:

> Out of curiosity, how many such options do we have around,
> i.e. options silently accepted but doing nothing?

I'm not sure.

The stated reason we do that is to avoid breaking Makefiles and such. 
For an option that actually affected semantics that would be a bad idea 
(in that now the user would expect to get semantics that they no longer 
get), but for options that do not affect semantics it's a way of making 
upgrades less painful.  If it were up to me, I might just remove the 
option, but leaving it around is the established protocol, for the 
reasons given above.

-- 
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304