kernel: Test laziness of certain arguments

{ buildPackages

, callPackage

, emptyFile

, perl

, bison ? null

, flex ? null

, nixosTests

}@args':

let overridableKernel =

lib.makeOverridable ({ # The kernel source tarball.

  src

            + toString (lib.attrNames (lib.toFunction args { }))

          ) overridableKernel;

      };

    in [ (nixosTests.kernel-generic.passthru.testsForKernel overridableKernel) ] ++ kernelTests;

      versionDoesNotDependOnPatchesEtc =

        builtins.seq

          (import ./generic.nix args' (args // (

          let explain = attrName:

            ''

              The ${attrName} attribute must be able to access the kernel.version attribute without an infinite recursion.

              That means that the kernel attrset (attrNames) and the kernel.version attribute must not depend on the ${attrName} argument.

              The fact that this exception is raised shows that such a dependency does exist.

              This is a problem for the configurability of ${attrName} in version-aware logic such as that in NixOS.

              Strictness can creep in through optional attributes, or assertions and warnings that run as part of code that shouldn't access what is checked.

            '';

          in {

            kernelPatches = throw (explain "kernelPatches");

            structuredExtraConfig = throw (explain "structuredExtraConfig");

            modDirVersion = throw (explain "modDirVersion");

          }))).version

          emptyFile;

    in [

      (nixosTests.kernel-generic.passthru.testsForKernel overridableKernel)

      versionDoesNotDependOnPatchesEtc

    ] ++ kernelTests;

  };

}))

}));

in overridableKernel