In reply to @ivy:faggot.sh
is there a way to define arbitrary variables in a .cabal file that are maintained in the outputted 2nix

After upgrading nix version from 2.28.4 -> 2.28.5 I am getting this error:

error:
       … while calling the 'derivationStrict' builtin
         at <nix/derivation-internal.nix>:37:12:
           36|
           37|   strict = derivationStrict drvAttrs;
             |            ^
           38|

       … while evaluating derivation 'ghc-shell-for-packages-0'
         whose name attribute is located at /nix/store/yhvvk386srxffsd7369j28lkfaav1bwp-source/pkgs/stdenv/generic/make-derivation.nix:480:13

       … while evaluating attribute 'NIX_GHC' of derivation 'ghc-shell-for-packages-0'
         at /nix/store/yhvvk386srxffsd7369j28lkfaav1bwp-source/pkgs/development/haskell-modules/generic-builder.nix:999:13:
          998|             ) "${buildPackages.glibcLocales}/lib/locale/locale-archive";
          999|             "NIX_${ghcCommandCaps}" = "${ghcEnv}/bin/${ghcCommand}";
             |             ^
         1000|             "NIX_${ghcCommandCaps}PKG" = "${ghcEnv}/bin/${ghcCommand}-pkg";

       (stack trace truncated; use '--show-trace' to show the full, detailed trace)

       error: builder for '/nix/store/7wdsyrqbm6dna640gz7sibp4i66cr9xz-cabal2nix-yesod-form.drv' failed with exit code 1;
       last 3 log lines:
       > *** parsing cabal file: /nix/store/kbv83vqvvc3gczpfz84jycrcp00yx81y-source/yesod-form/yesod-form: withBinaryFile: does not exist (No such file or directory)
       > $ nix-prefetch-url --unpack file:///nix/store/kbv83vqvvc3gczpfz84jycrcp00yx81y-source/yesod-form
       > cabal2nix: nix-prefetch-url: createProcess: posix_spawnp: does not exist (No such file or directory)
       For full logs, run:
         nix log /nix/store/7wdsyrqbm6dna640gz7sibp4i66cr9xz-cabal2nix-yesod-form.drv

Any known solution?

I had declared the flake input as github:yesodweb/yesod?dir=yesod-form and it seems that this notation has changed with the nix version update. https://github.com/NixOS/nix/pull/12801

So not related to haskell. Thanks for the quick reaction!