Is C++11 to be default for GCC 4.9?

Is C++11 to be default for GCC 4.9?

[Lars Hagström]

Hi,

I'm wondering whether GCC 4.9 will switch to -std=gnu++11 as default?

I did download and build 4.9 from git (through archlinux AUR) to see
if I could answer this myself, but I got slightly contradictory
results:

I got an error that implies that "auto" is not usable, which would
mean that C++11 is not enabled, but I also got a warning that implied
that gnu++11 is "enabled by default".

> error: ‘xdir’ does not name a type

> warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11 [enabled by default]

Or does the "enabled by default" bit mean something other than I think it means?

Thanks in advance for any insight you can offer.
/Lars

Re: Is C++11 to be default for GCC 4.9?

[Marc Glisse]

Wrong list, please send any follow-ups to gcc-help@gcc.gnu.org only.

On Fri, 24 Jan 2014, Lars Hagström wrote:

> I'm wondering whether GCC 4.9 will switch to -std=gnu++11 as default?

No. This is asked regularly, google should find the answer easily.

> I got an error that implies that "auto" is not usable, which would
> mean that C++11 is not enabled, but I also got a warning that implied
> that gnu++11 is "enabled by default".
>
>> error: ‘xdir’ does not name a type
>
>> warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11 [enabled by default]
>
> Or does the "enabled by default" bit mean something other than I think it means?

It is the warning that is enabled by default (in other messages you would 
see [-Wunused] or [-Wformat] etc to tell you which option controls this 
warning).

-- 
Marc Glisse

Re: Is C++11 to be default for GCC 4.9?

[pinskia]

> On Jan 24, 2014, at 1:26 AM, Marc Glisse <marc.glisse@inria.fr> wrote:
> 
> Wrong list, please send any follow-ups to gcc-help@gcc.gnu.org only.
> 
>> On Fri, 24 Jan 2014, Lars Hagström wrote:
>> 
>> I'm wondering whether GCC 4.9 will switch to -std=gnu++11 as default?
> 
> No. This is asked regularly, google should find the answer easily.

Considering GCC has not switched to c99 by default what makes someone think GCC should switch to c++11 by default?

-- Andrew

> 
>> I got an error that implies that "auto" is not usable, which would
>> mean that C++11 is not enabled, but I also got a warning that implied
>> that gnu++11 is "enabled by default".
>> 
>>> error: ‘xdir’ does not name a type
>> 
>>> warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11 [enabled by default]
>> 
>> Or does the "enabled by default" bit mean something other than I think it means?
> 
> It is the warning that is enabled by default (in other messages you would see [-Wunused] or [-Wformat] etc to tell you which option controls this warning).
> 
> -- 
> Marc Glisse

Re: Is C++11 to be default for GCC 4.9?

[Richard Sandiford]

Marc Glisse <marc.glisse@inria.fr> writes:
>> I got an error that implies that "auto" is not usable, which would
>> mean that C++11 is not enabled, but I also got a warning that implied
>> that gnu++11 is "enabled by default".
>>
>>> error: ‘xdir’ does not name a type
>>
>>> warning: non-static data member initializers only available with
>>> -std=c++11 or -std=gnu++11 [enabled by default]
>>
>> Or does the "enabled by default" bit mean something other than I think
>> it means?
>
> It is the warning that is enabled by default (in other messages you would 
> see [-Wunused] or [-Wformat] etc to tell you which option controls this 
> warning).

I can definitely sympathise with reading the message the other way though.
If that's the only output you see, the natural assumption is that the
"enabled by default" applies to the thing just before it.

Any objections to changing it to "this warning is enabled by default"
or "warning enabled by default"?  Or is that too verbose?

Thanks,
Richard

Re: Is C++11 to be default for GCC 4.9?

[Jonathan Wakely]

On 26 January 2014 16:17, Richard Sandiford wrote:
> I can definitely sympathise with reading the message the other way though.
> If that's the only output you see, the natural assumption is that the
> "enabled by default" applies to the thing just before it.
>
> Any objections to changing it to "this warning is enabled by default"
> or "warning enabled by default"?  Or is that too verbose?

The former seems far too verbose to me, I could live with the latter
(even though it's only a few characters shorter!)

Re: Is C++11 to be default for GCC 4.9?

[Florian Weimer]

On 01/26/2014 05:17 PM, Richard Sandiford wrote:
> Marc Glisse <marc.glisse@inria.fr> writes:
>>> I got an error that implies that "auto" is not usable, which would
>>> mean that C++11 is not enabled, but I also got a warning that implied
>>> that gnu++11 is "enabled by default".
>>>
>>>> error: ‘xdir’ does not name a type
>>>
>>>> warning: non-static data member initializers only available with
>>>> -std=c++11 or -std=gnu++11 [enabled by default]
>>>
>>> Or does the "enabled by default" bit mean something other than I think
>>> it means?
>>
>> It is the warning that is enabled by default (in other messages you would
>> see [-Wunused] or [-Wformat] etc to tell you which option controls this
>> warning).
>
> I can definitely sympathise with reading the message the other way though.
> If that's the only output you see, the natural assumption is that the
> "enabled by default" applies to the thing just before it.
>
> Any objections to changing it to "this warning is enabled by default"
> or "warning enabled by default"?  Or is that too verbose?

We should show the flag that enables the warning, so that users can use 
the -Wno- variant to disable it if they want.  Or does "enabled by 
default" mean that no such -Wno- flag exists?

-- 
Florian Weimer / Red Hat Product Security Team

Re: Is C++11 to be default for GCC 4.9?

[Marc Glisse]

On Mon, 27 Jan 2014, Florian Weimer wrote:

> On 01/26/2014 05:17 PM, Richard Sandiford wrote:
>> Any objections to changing it to "this warning is enabled by default"
>> or "warning enabled by default"?  Or is that too verbose?

The second one looks fine to me, need to find a real reviewer now ;-)

> We should show the flag that enables the warning, so that users can use the 
> -Wno- variant to disable it if they want.  Or does "enabled by default" mean 
> that no such -Wno- flag exists?

Exactly. -std=c++11 is the right way to make this warning quiet.

-- 
Marc Glisse

Re: Is C++11 to be default for GCC 4.9?

[Ryan Hill]

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On Sun, 26 Jan 2014 16:17:08 +0000
Richard Sandiford <rdsandiford@googlemail.com> wrote:

> Marc Glisse <marc.glisse@inria.fr> writes:
> >> I got an error that implies that "auto" is not usable, which would
> >> mean that C++11 is not enabled, but I also got a warning that implied
> >> that gnu++11 is "enabled by default".
> >>
> >>> error: ‘xdir’ does not name a type
> >>
> >>> warning: non-static data member initializers only available with
> >>> -std=c++11 or -std=gnu++11 [enabled by default]
> >>
> >> Or does the "enabled by default" bit mean something other than I think
> >> it means?
> >
> > It is the warning that is enabled by default (in other messages you would 
> > see [-Wunused] or [-Wformat] etc to tell you which option controls this 
> > warning).
> 
> I can definitely sympathise with reading the message the other way though.
> If that's the only output you see, the natural assumption is that the
> "enabled by default" applies to the thing just before it.
> 
> Any objections to changing it to "this warning is enabled by default"
> or "warning enabled by default"?  Or is that too verbose?

If there's no flag to toggle the warning then why print anything?  To me
"enabled by default" implies there's some way to disable it.


-- 
Ryan Hill                        psn: dirtyepic_sk
   gcc-porting/toolchain/wxwidgets @ gentoo.org

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