[ITK-users] vnl_numeric_traits.h constexpr _aka_ ITK and C++11

[Pol Monsó Purtí]

Hello all,

Thanks Matt, the dependencies were already compiled correctly. Stay put as
the plot thickens.

I've reproduced the steps that I had done to compile ITK before and it
worked, so I kept searching for the cause of the error and it boils down to
this:

If I compile with ccmake, it fails with the mentioned errors.

if I compile with cmake, it works.

In both cases setting the flag CMAKE_CXX_FLAGS to -std=c++11

So my guess is that when running ccmake, the first configure sets the
headers wrong and that doesn't get fixed when setting the -std=c++11 after
the first configure is done.

Indeed it doesn't happen with ccmake -DCMAKE_CXX_FLAGS=-std=c++11 . (The '
' are apparently unnecessary)

Cheers!

Pol

2015-04-23 0:19 GMT+02:00 Matt McCormick <matt.mccormick at kitware.com>:

> Hi Pol,
>
> Make sure to build ITK and everything that builds against ITK by
> specifying the '-std=c++11' flag beginning with the initial CMake
> configuration from a fresh build. By adding this flag, it is like
> specifying a different compiler, and there are some initial
> configuration try_compile tests that extract information about the
> compiler.  Specify it with
>
>   cmake -DCMAKE_CXX_FLAGS='std=c++11' ~/src/ITK
>
> HTH,
> Matt
>
> On Wed, Apr 22, 2015 at 5:57 PM, Pol Monsó Purtí <lluna.nova at gmail.com>
> wrote:
> > Hello all,
> >
> > Today I moved&updated the ITK directory so I had to rebuild everything.
> I am
> > compiling with -std=c++11
> >
> > Misteriously, now I am getting the error
> >
> >
> /Users/monso/code/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_numeric_traits.h:437:68:
> > error: 'constexpr' needed for in-class initialization of static data
> member
> > 'const long double vnl_numeric_traits<long double>::maxval' of
> non-integral
> > type [-fpermissive]
> >    static const long double maxval
> > VCL_STATIC_CONST_INIT_FLOAT_DECL(1.7976931348623157E+308);
> >
> > which apparently it's a bug that was there around 2011. How come it came
> > back? Any ideas?
> >
> > This is using the master branch of
> > https://github.com/InsightSoftwareConsortium/ITK.git
> >
> > See
> http://public.kitware.com/pipermail/community/2013-December/004580.html
> >
> > I am on OSX, using g++-mp-4.9
> >
> > I tried setting the vcl_include_cxx_0x, same result.
> >
> > I don't know how I fixed this or if I had the issue (I kind of recall
> this),
> > but it worked before. So I tried with ITK4.7.1 from the website, same
> > result.
> >
> > Cheers,
> >
> > Pol
> >
> >
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