[patch] Clarify interaction of -Wnarrowing with -std

[Jason Merrill]

On 02/19/2016 07:42 AM, Jonathan Wakely wrote:
> In PR69864 Manu suggests improving the docs to explain that
> -Wnarrowing sometimes produces errors not warnings.
>
> I think the right way to do that is clarify how it interacts with
> -std. Specifically that the effect of -Wnarrowing listed first in the
> manual *only* applies to C++98 modes, For all later modes (not just
> with -std=c++11 as it says now), narrowing conversions produce errors
> or warnings by default.
>
> OK for trunk?

OK, thanks.

Jason