Python 3.10 fails to apply python-3.x-distutils-C++.patch

[allonhadaya-maven]

Describe the bug

Using devenv 1.8.2 (aarch64-darwin) I am able to build the following minimal Python 3.10 shell without error:

$ devenv shell
• Added input 'nixpkgs-python':
    'github:cachix/nixpkgs-python/188ffc273f679a2d95a1c8aba0be083545417bdd' (2026-03-03)
• Added input 'nixpkgs-python/flake-compat':
    'github:edolstra/flake-compat/5edf11c44bc78a0d334f6334cdaf7d60d732daab' (2025-12-29)
• Added input 'nixpkgs-python/nixpkgs':
    follows 'nixpkgs'
• Using Cachix caches: nixpkgs-python, devenv
✓ Building shell in 456s
✨ devenv 1.8.2 is out of date. Please update to 2.0.4: https://devenv.sh/getting-started/#installation
$ python3 --version
Python 3.10.20
$ which python3
/nix/store/xjlknfhl0aig8g3m55y4anvvn9ar4i8r-python3-3.10.20-env/bin/python3

Using a recent rev from main devenv 2.0.5+7cd1a09 (aarch64-darwin), I encounter the following error building the shell:

    ✗ error: Cannot build '/nix/store/631qixg0k9kw3a5l0qmgrrm336d63nx9-python3-3.10.20.drv'.
    ✗ error: Cannot build '/nix/store/d00b7dm95ab4q61sqhw4gqb512c4y3x6-python3-3.10.20-env.drv'.
    ✗ error: Build failed due to failed dependency
    ✗ error: Cannot build '/nix/store/3jzxarill8v5mixjbji84zi9k1qfhrhs-devenv-profile.drv'.
    ✗ error: Cannot build '/nix/store/ygwam62hrmh2mqjzclllbhl9hzalib0w-devenv-shell.drv'.

error: Cannot build '/nix/store/d00b7dm95ab4q61sqhw4gqb512c4y3x6-python3-3.10.20-env.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/31h9ywaz3nkbrbbpydkmvah95bznj7xd-python3-3.10.20-env
error: Cannot build '/nix/store/3jzxarill8v5mixjbji84zi9k1qfhrhs-devenv-profile.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/xihqnwjv3qrs3y2gb6r1k1xlr3k4vhql-devenv-profile
error: Cannot build '/nix/store/631qixg0k9kw3a5l0qmgrrm336d63nx9-python3-3.10.20.drv'.
       Reason: builder failed with exit code 1.
       Output paths:
         /nix/store/70b7qbdm9kh3ahl86b2s8g3wpjprlzy5-python3-3.10.20
       Last 25 log lines:
       > applying patch /nix/store/n97jb2skcqcwh9dyxlgjf2pidsc74f77-3.10-no-ldconfig.patch
       > patching file Lib/ctypes/util.py
       > applying patch /nix/store/r112dk8w7zvdjipki58ch00m825li7fq-virtualenv-permissions.patch
       > patching file Lib/venv/__init__.py
       > Hunk cachix/devenv#1 succeeded at 451 with fuzz 2 (offset 72 lines).
       > applying patch /nix/store/lpfs02z2i2hamz9f50p4bz6v0fs0600j-mimetypes.patch
       > patching file Lib/mimetypes.py
       > Hunk cachix/devenv#1 succeeded at 46 (offset 6 lines).
       > applying patch /nix/store/9kwzs3pplms8sijf55sdryypzvic4x1s-python-3.x-distutils-C++.patch
       > patching file Lib/_osx_support.py
       > patching file Lib/distutils/cygwinccompiler.py
       > Hunk cachix/devenv#1 succeeded at 123 (offset -2 lines).
       > Hunk cachix/devenv#2 succeeded at 140 (offset -2 lines).
       > Hunk cachix/devenv#3 succeeded at 170 (offset -2 lines).
       > Hunk cachix/devenv#4 succeeded at 310 (offset -2 lines).
       > patching file Lib/distutils/sysconfig.py
       > Hunk cachix/devenv#1 FAILED at 170.
       > Hunk cachix/devenv#2 FAILED at 187.
       > Hunk cachix/devenv#3 succeeded at 254 (offset 46 lines).
       > 2 out of 3 hunks FAILED -- saving rejects to file Lib/distutils/sysconfig.py.rej
       > patching file Lib/distutils/unixccompiler.py
       > Hunk cachix/devenv#3 FAILED at 183.
       > 1 out of 3 hunks FAILED -- saving rejects to file Lib/distutils/unixccompiler.py.rej
       > patching file Makefile.pre.in
       > Hunk cachix/devenv#1 succeeded at 626 (offset 42 lines).
       For full logs, run:
         nix log /nix/store/631qixg0k9kw3a5l0qmgrrm336d63nx9-python3-3.10.20.drv
error: Build failed due to failed dependency
error: Cannot build '/nix/store/ygwam62hrmh2mqjzclllbhl9hzalib0w-devenv-shell.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/c32pgv99v7fmv8l07nr2yr0dhlnsd1xs-devenv-shell

Looking at the various spots in nixpkgs-python/flake.nix where we replacePatch or filterOutPatch on python-3.x-distutils-C++.patch, I don't see any conditions that should match the 3.10.20 version:

{
  condition = version: versionInBetween version "3.7.3" "3.7.1";
  override = replacePatch "python-3.x-distutils-C++.patch" ...;
}

{
  condition = version: versionInBetween version "3.7.4" "3.7.3";
  override = replacePatch "python-3.x-distutils-C++.patch" ./patches/python-3.7.3-distutils-C++.patch;
}

{
  condition =
    version: versionInBetween version "3.7.2" "3.7" || versionInBetween version "3.6.8" "3.6.6";
  override = replacePatch "python-3.x-distutils-C++.patch" ...;
}

{
  condition = version: versionInBetween version "3.6.6" "3.4";
  override = replacePatch "python-3.x-distutils-C++.patch" ...;
}

# no C++ patch for 3.3
{
  condition = version: versionInBetween version "3.4" "3.0";
  override = filterOutPatch "python-3.x-distutils-C++.patch";
}

Presumably we're attempting to apply this patch defined upstream in nixpkgs from the else branch:

  ++ optionals (hasDistutilsCxxPatch && pythonOlder "3.12") [
    # Fix for http://bugs.python.org/issue1222585
    # Upstream distutils is calling C compiler to compile C++ code, which
    # only works for GCC and Apple Clang. This makes distutils to call C++
    # compiler when needed.
    (
      if pythonAtLeast "3.11" then
        ./3.11/python-3.x-distutils-C++.patch
      else
        fetchpatch {
          url = "https://bugs.python.org/file48016/python-3.x-distutils-C++.patch";
          sha256 = "1h18lnpx539h5lfxyk379dxwr8m2raigcjixkf133l4xy3f4bzi2";
        }
    )
  ]

To reproduce

devenv.nix:

{
  languages.python = {
    enable = true;
    version = "3.10";
  };
}

devenv.yaml:

inputs:
  nixpkgs-python:
    url: github:cachix/nixpkgs-python
    inputs:
      nixpkgs:
        follows: nixpkgs

devenv.lock:

{
  "nodes": {
    "devenv": {
      "locked": {
        "dir": "src/modules",
        "lastModified": 1773714831,
        "narHash": "sha256-qUJ59Zj+M3OomXnPVx/R+AtloTuzH2zZBsK1vrVo9SA=",
        "owner": "cachix",
        "repo": "devenv",
        "rev": "6e82f48e9ae25c7a2560fce5324d873d8944a008",
        "type": "github"
      },
      "original": {
        "dir": "src/modules",
        "owner": "cachix",
        "repo": "devenv",
        "type": "github"
      }
    },
    "flake-compat": {
      "flake": false,
      "locked": {
        "lastModified": 1747046372,
        "narHash": "sha256-CIVLLkVgvHYbgI2UpXvIIBJ12HWgX+fjA8Xf8PUmqCY=",
        "owner": "edolstra",
        "repo": "flake-compat",
        "rev": "9100a0f413b0c601e0533d1d94ffd501ce2e7885",
        "type": "github"
      },
      "original": {
        "owner": "edolstra",
        "repo": "flake-compat",
        "type": "github"
      }
    },
    "nixpkgs": {
      "inputs": {
        "nixpkgs-src": "nixpkgs-src"
      },
      "locked": {
        "lastModified": 1773704619,
        "narHash": "sha256-LKtmit8Sr81z8+N2vpIaN/fyiQJ8f7XJ6tMSKyDVQ9s=",
        "owner": "cachix",
        "repo": "devenv-nixpkgs",
        "rev": "906534d75b0e2fe74a719559dfb1ad3563485f43",
        "type": "github"
      },
      "original": {
        "owner": "cachix",
        "ref": "rolling",
        "repo": "devenv-nixpkgs",
        "type": "github"
      }
    },
    "nixpkgs-python": {
      "inputs": {
        "flake-compat": "flake-compat",
        "nixpkgs": [
          "nixpkgs"
        ]
      },
      "locked": {
        "lastModified": 1772559541,
        "narHash": "sha256-1cWCYOnOz3K7FchI9IbIbu1qhi68mSNZSuYlE5jEv1I=",
        "owner": "cachix",
        "repo": "nixpkgs-python",
        "rev": "188ffc273f679a2d95a1c8aba0be083545417bdd",
        "type": "github"
      },
      "original": {
        "owner": "cachix",
        "repo": "nixpkgs-python",
        "type": "github"
      }
    },
    "nixpkgs-src": {
      "flake": false,
      "locked": {
        "lastModified": 1773597492,
        "narHash": "sha256-hQ284SkIeNaeyud+LS0WVLX+WL2rxcVZLFEaK0e03zg=",
        "owner": "NixOS",
        "repo": "nixpkgs",
        "rev": "a07d4ce6bee67d7c838a8a5796e75dff9caa21ef",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
        "ref": "nixpkgs-unstable",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "root": {
      "inputs": {
        "devenv": "devenv",
        "nixpkgs": "nixpkgs",
        "nixpkgs-python": "nixpkgs-python"
      }
    }
  },
  "root": "root",
  "version": 7
}

Version

devenv 2.0.5+7cd1a09 (aarch64-darwin)

[allonhadaya-maven]

Thanks for taking a look @sandydoo!

Small update: I was able to build Python 3.11 successfully, but 3.9 produces the same error as 3.10.

[sandydoo]

Could you run devenv update and check again? I can't replicate this one.

I would also suggest removing the nixpkgs override:

inputs:
  nixpkgs:
    follows: nixpkgs

I added a note in the README about this.

[sandydoo]

Ah, okay, it fails to build against unstable.

We'll get this fixed, but the underlying issue is the follows. We don't have the bandwidth to keep up with unstable at the moment, so it's best to use whatever this repo has pinned.