From b40c514e9a544e4947d7b0dfd54381c0eebeda88 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Robert=20Sch=C3=BCtz?= <nix@dotlambda.de>
Date: Mon, 27 Jul 2026 13:56:37 -0700
Subject: [PATCH] python3Packages.pythonMetadataCheckHook: rewrite comparison
 in Python

---
 .../interpreters/python/hooks/default.nix     |  1 +
 .../python-metadata-check-hook-compare.py     | 21 +++++++++++++++++++
 .../hooks/python-metadata-check-hook.sh       | 10 +--------
 3 files changed, 23 insertions(+), 9 deletions(-)
 create mode 100644 pkgs/development/interpreters/python/hooks/python-metadata-check-hook-compare.py

diff --git a/pkgs/development/interpreters/python/hooks/default.nix b/pkgs/development/interpreters/python/hooks/default.nix
index 183bc7af3592..afe3f132ac64 100644
--- a/pkgs/development/interpreters/python/hooks/default.nix
+++ b/pkgs/development/interpreters/python/hooks/default.nix
@@ -369,6 +369,7 @@ in
         inherit pythonInterpreter pythonSitePackages;
         pythonWithPackaging = lib.getExe (pythonOnBuildForHost.withPackages (ps: [ ps.packaging ]));
         retrieveMetadata = ./python-metadata-check-hook-retrieve.py;
+        compareMetadata = ./python-metadata-check-hook-compare.py;
       };
       meta = {
         maintainers = [ lib.maintainers.dotlambda ];
diff --git a/pkgs/development/interpreters/python/hooks/python-metadata-check-hook-compare.py b/pkgs/development/interpreters/python/hooks/python-metadata-check-hook-compare.py
new file mode 100644
index 000000000000..09de970cbd4c
--- /dev/null
+++ b/pkgs/development/interpreters/python/hooks/python-metadata-check-hook-compare.py
@@ -0,0 +1,21 @@
+from packaging.version import InvalidVersion, parse, Version
+from sys import argv, exit
+
+
+derivation_pname = argv[1]
+derivation_version = argv[2]
+metadata_version = argv[3]
+
+
+try:
+    parse(derivation_version)
+except InvalidVersion as e:
+    print(e)
+    print('Make sure you follow https://github.com/NixOS/nixpkgs/blob/master/pkgs/README.md#versioning.')
+    exit(1)
+
+if Version(derivation_version) != Version(metadata_version):
+    print(f"The '{derivation_pname}' derivation has version '{derivation_version}' but .dist-info/METADATA specifies version '{metadata_version}'.")
+    print('This usually means that the wrong version is hardcoded in pyproject.toml or setup.{py,cfg}.')
+    print("Use the pyprojectVersionPatchHook or patch the version manually so that the project metadata matches the derivation's version.")
+    exit(1)
diff --git a/pkgs/development/interpreters/python/hooks/python-metadata-check-hook.sh b/pkgs/development/interpreters/python/hooks/python-metadata-check-hook.sh
index 2f2dfd126f9c..a328f319b00c 100644
--- a/pkgs/development/interpreters/python/hooks/python-metadata-check-hook.sh
+++ b/pkgs/development/interpreters/python/hooks/python-metadata-check-hook.sh
@@ -21,15 +21,7 @@ pythonMetadataCheckPhase() {
   metadataVersion="$(PYTHONPATH="$pythonMetadataCheckOutput/@pythonSitePackages@:$PYTHONPATH" \
     @pythonInterpreter@ -P @retrieveMetadata@ "$derivationPname")"
 
-  # check that both versions can be parsed
-  @pythonWithPackaging@ -c "from packaging.version import Version; from sys import argv; Version(argv[1]); Version(argv[2])" "$derivationVersion" "$metadataVersion"
-
-  if @pythonWithPackaging@ -c "from packaging.version import Version; from sys import argv, exit; exit(Version(argv[1]) == Version(argv[2]))" "$derivationVersion" "$metadataVersion"; then
-    echo "The '$derivationPname' derivation has version '$derivationVersion' but .dist-info/METADATA specifies version '$metadataVersion'."
-    echo "This usually means that the wrong version is hardcoded in pyproject.toml or setup.{py,cfg}."
-    echo "Use the pyprojectVersionPatchHook or patch the version manually so that the project metadata matches the derivation's version."
-    exit 1
-  fi
+  @pythonWithPackaging@ @compareMetadata@ "$derivationPname" "$derivationVersion" "$metadataVersion"
 }
 
 if [ -z "${dontCheckPythonMetadata-}" ]; then