hydra fails to build on release-17.03

[basvandijk]

I noticed that hydra fails to build on the latest release-17.03 (8d9c838):

$ nix-build -A hydra
...
Making all in hydra-eval-jobs
make[3]: Entering directory '/tmp/nix-build-hydra-2017-06-22.drv-0/hydra-803833aba77e1082c14857aa26933fc7fe5ae190-src/src/hydra-eval-jobs'
g++ -DHAVE_CONFIG_H -I. -I../..    -I/nix/store/avm18zin1yx7h93gw8lq0kazlwl0ip28-boehm-gc-7.6.0-dev/include -I/nix/store/gx58k0g0z3vcqcw9wbg8hdv79rnddhd3-nix-1.12pre5511_c94f3d55-dev/include/nix -g -O2 -std=c++17 -include nix/config.h -c -o hydra-eval-jobs.o hydra-eval-jobs.cc
hydra-eval-jobs.cc: In function 'void findJobsWrapped(nix::EvalState&, nix::JSONObject&, const AutoArgs&, nix::Value&, const string&)':
hydra-eval-jobs.cc:111:47: error: cannot convert 'nix::DrvInfo' to 'bool' for argument '3' to 'std::experimental::fundamentals_v1::optional<nix::DrvInfo> nix::getDerivation(nix::EvalState&, nix::Value&, bool)'
         if (getDerivation(state, v, drv, false)) {
                                               ^
hydra-eval-jobs.cc:116:21: error: 'std::__cxx11::string nix::DrvInfo::system' is private within this context
             if (drv.system == "unknown")
                     ^~~~~~
In file included from hydra-eval-jobs.cc:12:0:
/nix/store/gx58k0g0z3vcqcw9wbg8hdv79rnddhd3-nix-1.12pre5511_c94f3d55-dev/include/nix/get-drvs.hh:21:20: note: declared private here
     mutable string system;
                    ^~~~~~
hydra-eval-jobs.cc:121:37: error: 'std::__cxx11::string nix::DrvInfo::name' is private within this context
             res.attr("nixName", drv.name);
                                     ^~~~
In file included from hydra-eval-jobs.cc:12:0:
/nix/store/gx58k0g0z3vcqcw9wbg8hdv79rnddhd3-nix-1.12pre5511_c94f3d55-dev/include/nix/get-drvs.hh:20:20: note: declared private here
     mutable string name;
                    ^~~~
hydra-eval-jobs.cc:122:36: error: 'std::__cxx11::string nix::DrvInfo::system' is private within this context
             res.attr("system", drv.system);
                                    ^~~~~~
In file included from hydra-eval-jobs.cc:12:0:
/nix/store/gx58k0g0z3vcqcw9wbg8hdv79rnddhd3-nix-1.12pre5511_c94f3d55-dev/include/nix/get-drvs.hh:21:20: note: declared private here
     mutable string system;
                    ^~~~~~

@edolstra, @zimbatm I guess this is related to the recent nixUnstable upgrade.

[edolstra]

Yeah, we should update Hydra in Nixpkgs. Upstream does build http://hydra.nixos.org/eval/1377616

[domenkozar]

If someone can make a PR to bump Hydra I'd be happy to review that!

[basvandijk]

@domenkozar see: #27625 and #27626.