flake-utils.lib.mkApp is broken with nix 2.8

[Lunarequest]

Describe the bug

To Reproduce

Steps to reproduce the behavior:

1. use nix run on a repo with the an app made with flake-utils.lib.mkApp
2. errors with error: attribute 'defaultApp.x86_64-linux' should have type 'derivation'

Expected behavior
the app executes normally

System information
nix 2.8.0 linux

Additional context
nix 2.8.0 has more strictness the nix 2.7 which has broken flake-utils

[zimbatm]

is that fixed?

[TristanCacqueray]

This issue is still happening when using defaultApp = flake-utils.lib.mkApp { drv = package; }; with nix-2.8 .
This seems to work though: apps.default = flake-utils.lib.mkApp { drv = package; }.

[tv42]

It does not seem like this issue should have been closed.

[johnrichardrinehart]

EDIT: Discovered that the problem I was describing underneath the divider, below, was because I wasn't conforming to c0e246b . After respecting that commit and moving my defaultApp value to apps.default nix run . works fine.

        apps = rec {
          go_1_18-fips = flake-utils.lib.mkApp { drv = packages.go_1_18-fips;  exePath = "/bin/go";};
          default = go_1_18-fips;
        };

---

I have a bunch of files in $out/bin and trying to select only one for defaultApp with exePath or name fails with the above error. It doesn't matter if I try apps.defaultApp or defaultApp.

        apps.defaultApp =  flake-utils.lib.mkApp { drv = packages.go_1_18-fips;  name = "go";};

However, the below works just fine as nix run .#go_1_18-fips

        apps.go_1_18-fips = flake-utils.lib.mkApp { drv = packages.go_1_18-fips;  name = "go";};

It's possible this has been the case for as long as nix 2.8. But, in my case

$ nix --version
nix (Nix) 2.10.3

$ cat flake.lock | grep numtide -C 10
{
  "nodes": {
    "flake-utils": {
      "locked": {
        "lastModified": 1659877975,
        "narHash": "sha256-zllb8aq3YO3h8B/U0/J1WBgAL8EX5yWf5pMj3G0NAmc=",
        "owner": "numtide",
        "repo": "flake-utils",
        "rev": "c0e246b9b83f637f4681389ecabcb2681b4f3af0",
        "type": "github"
      },
      "original": {
        "owner": "numtide",
        "repo": "flake-utils",
        "type": "github"
      }
    },