Re: C++11 flags for jhbuild

[Ian Martin <martin_id vodafone co nz>]

On 20/07/15 01:45, Murray Cumming wrote:
> On Sun, 2015-07-19 at 15:44 +0200, Murray Cumming wrote:
> > On Sun, 2015-07-19 at 23:09 +1200, Ian Martin wrote:
> > > Hi,
> > > I'm trying to build gtkmm with jhbuild.  glibmm fails with a number of
> > > warnings and errors starting with
> > > > warning: identifier 'decltype' is a keyword in C++11 [-Wc++0x-compat]
> > > >
> > > > /opt/gnome/include/sigc++-2.0/sigc++/functors/functor_trait.h:91:3:
> > > > warning: identifier 'nullptr' is a keyword in C++11 [-Wc++0x-compat]
> > > >
> > > > /opt/gnome/include/sigc++-2.0/sigc++/functors/functor_trait.h:91:36:
> > > > error: 'decltype' has not been declared
> > > >
> > > > /opt/gnome/include/sigc++-2.0/sigc++/functors/functor_trait.h:96:44:
> > > > error: 'nullptr' was not declared in this scope
> > > >       = sizeof(check(static_cast<T_functor*>(nullptr))) == sizeof(int)
> > > I'm guessing this means I need to enable C++11 within jhbuild.  Do I do
> > > this in my .jhbuildrc or should this be a compiler flag added within the
> > > glibmm configure.ac?
> > This seems to be a -Wc++0x-compat warning. Do you have that in your
> > jhbuild config file somehow?
> Or maybe you just need to run autogen.sh again.
Excluding comments, my .jhbuildrc contains the following:
> modulesets_dir = '/usr/share/jhbuild/modulesets'
> modules = [ 'gtkmm', 'cairomm' ]
> checkoutroot = '/data/checkout/gnome-source/'
> prefix = '/opt/gnome'
and rerunning ./autogen.sh gives the same errors.

I've tried adding
autogenargs='-std=c++11'
to jhbuildrc, but that blocked glib building with "unknown compiler 
flag  -std=c++11 ".

I'm running Debian testing, and use C++11 in other projects without any 
problem, so I assume my build chain is set up OK.
> This seems to be a -Wc++0x-compat warning. Do you have that in your
> jhbuild config file somehow?
The warnings confirm this: one is
> /opt/gnome/include/sigc++-2.0/sigc++/signal.h:257:7: warning: 'auto' 
> changes meaning in C++11; please remove it [-Wc++0x-compat]
>        auto tmp_ = end();
I haven't added it myself.

Update: can build glibmm by adding
MM_AX_CXX_COMPILE_STDCXX_11([noext],[mandatory])
to configure.ac

I'm no autotools genius, but it looks to me like sigc++ is now dependent 
on c++11, which is going to create dependencies for all downstream 
projects.  If I'm correct, do you want me to create the bug report and 
patches?

Ian.

Ian