On Sun, Oct 23, 2011 at 8:48 PM, Paolo Carlini <paolo.carl...@oracle.com> wrote:
> Hi,
>
> On 10/24/2011 03:30 AM, Gabriel Dos Reis wrote:
>>
>> We do not use -W or -Wno- to suppressed *required* diagnostics. So, when
>> -std=c++0x, -Wno-narrowing should not have any effect.
>
> Personally, I have no problem with this, but note, I'm not inventing
> anything new here, the behavior you are discussing *pre*-dates my patch and
> I feel a little nervous about changing it. If you think you can approve this
> part of rhe patch, I'll change it as you want and resend.
Let me quote again the part of the patch under discussion:
- /* If we're allowing C++0x constructs, don't warn about C++0x
- compatibility problems. */
if (cxx_dialect == cxx0x)
- warn_cxx0x_compat = 0;
+ {
+ /* If we're allowing C++0x constructs, don't warn about C++98
+ identifiers which are keywords in C++0x. */
+ warn_cxx0x_compat = 0;
+ if (warn_narrowing == -1)
+ warn_narrowing = 1;
+ }
+ else if (warn_narrowing == -1)
+ warn_narrowing = 0;
+
Before the patch, -std=c++0x effectively put off -Wc++0x-compat because we
are compiling c++98/c++03 code, so we can only *warn* about possible
compatibility conflict with C++11. However, the narrowing diagnostic required
by C++11 is NOT a warning. It is a diagnostic. The way we alter a standard
mandate is through some -fflag, e.g. -fpermissive.
What the above patch fragment is doing is to turn on a *warning*.
When -std=c++0x
is in effect, narrowing is no longer a warning. It is an error by default.
