why there is a varible used but never defined while building?

[castleKing1997]

I'm trying my best to install the software purify. I am in the 94% of the whole procedure. I feel that I'm only one step away from success. But there are still some problems there

/home/luochong/software/gcc7.3/include/c++/7.3.0/bits/std_function.h:685:7: error: ‘std::function<_Res(_ArgTypes ...)>::function(_Functor) [with _Functor = purify::operators::init_FFT_2d(const t_uint&, const t_uint&, const t_real&, purify::operators::fftw_plan) [with T = Eigen::Matrix<std::complex, -1, 1>; sopt::t_uint = long unsigned int; sopt::treal = double]::<lambda(Eigen::Matrix<std::complex, -1, 1>&, const Eigen::Matrix<std::complex, -1, 1>&)>; = void; = void; _Res = void; _ArgTypes = {Eigen::Matrix<std::complex, -1, 1, 0, -1, 1>&, const Eigen::Matrix<std::complex, -1, 1, 0, -1, 1>&}]’, declared using local type ‘purify::operators::init_FFT_2d(const t_uint&, const t_uint&, const t_real&, purify::operators::fftw_plan) [with T = Eigen::Matrix<std::complex, -1, 1>; sopt::t_uint = long unsigned int; sopt::treal = double]::<lambda(Eigen::Matrix<std::complex, -1, 1>&, const Eigen::Matrix<std::complex, -1, 1>&)>’, is used but never defined [-fpermissive]

How to fix it?

[Luke-Pratley]

@castleKing1997 Is this trying to compile the main executable? Did CMake find everything needed?

[castleKing1997]

@Luke-Pratley We managed to build purify on another PC without encountering this issue. This could be an operating system problem?

[Luke-Pratley]

@castleKing1997 It is possible... We test against linux and mac. It might depend on the library versions you are using. Check the front page https://github.com/astro-informatics/purify for what versions of different libraries we expect.

If you have more problems after checking this, it would be helpful to see more information about the system and what settings you are using.