From a76d0f23d837022b424c7ab38c2601b23a8d2da5 Mon Sep 17 00:00:00 2001
From: Mykola Orliuk <virkony@gmail.com>
Date: Thu, 13 Nov 2025 21:58:15 +0100
Subject: [PATCH] python3Packages.amazon-ion: include c_ext module

This should bring 60x speed up in parsing text Ion.

Resolves #461284
---
 .../python-modules/amazon-ion/default.nix     | 56 ++++++++++++++++++-
 pkgs/top-level/python-packages.nix            |  2 +-
 2 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/pkgs/development/python-modules/amazon-ion/default.nix b/pkgs/development/python-modules/amazon-ion/default.nix
index 0d4a9bd1578b..6198971bfa5b 100644
--- a/pkgs/development/python-modules/amazon-ion/default.nix
+++ b/pkgs/development/python-modules/amazon-ion/default.nix
@@ -4,12 +4,14 @@
   cbor2,
   docopt,
   fetchFromGitHub,
+  fetchpatch2,
   jsonconversion,
   pytestCheckHook,
   pytest_7,
   setuptools,
   six,
   tabulate,
+  cmake,
 }:
 
 buildPythonPackage rec {
@@ -23,15 +25,60 @@ buildPythonPackage rec {
     tag = "v${version}";
     # Test vectors require git submodule
     fetchSubmodules = true;
-    hash = "sha256-ZnslVmXE2YvTAkpfw2lbpB+uF85n/CvA22htO/Y7yWk=";
+    leaveDotGit = true; # During ion-c submodule build git history/hash used to infer version
+    postFetch = ''
+      # Generated file should match output of command in ion-c/cmake/VersionHeader.cmake
+      # Run Git before creating any files to avoid triggering false dirty suffix.
+      (cd "$out/ion-c" && v="$(git describe --long --tags --dirty --match "v*")" && echo -n "$v" > .nixpkgs-patching-IONC_FULL_VERSION.txt)
+
+      # Based on https://github.com/NixOS/nixpkgs/blob/183125f9/pkgs/build-support/fetchgit/nix-prefetch-git#L358
+      find "$out" -name .git -exec rm -rf '{}' '+'
+    '';
+    hash = "sha256-VBbxGXPAwS3jwEsm64yEKqJKVKGvPStboLjHoRcoonE=";
   };
 
+  patches = [
+    # backport changes that adapt code to more strict compilers
+    (fetchpatch2 {
+      name = "46aebb0-Address-incompatible-pointer-errors.patch";
+      url = "https://github.com/amazon-ion/ion-c/commit/46aebb0b650a4cf61425ef1a8e78e2443023e853.patch?full_index=1";
+      hash = "sha256-5qzSbZV9Oe5soJzkyCtVtWejedLEjAz7yuVotATPmbs=";
+      stripLen = 1;
+      extraPrefix = "ion-c/";
+    })
+  ];
+
   postPatch = ''
     substituteInPlace setup.py \
       --replace "'pytest-runner'," ""
+
+    # Ion C building is in _download_ion_c() which will try to remove sources and re-download
+    substituteInPlace install.py \
+      --replace-fail "isdir(_CURRENT_ION_C_DIR)" "False"
+    substituteInPlace install.py \
+      --replace-fail "check_call(['git'" "check_call(['true'"
+
+    # Ion-C infers version based on Git. But there are issues with making .git folders deterministic.
+    # See https://github.com/NixOS/nixpkgs/issues/8567
+    # Hence, we'll inject version ourselves
+    substituteInPlace ion-c/cmake/VersionHeader.cmake \
+      --replace-fail 'set(IONC_FULL_VERSION "''${CMAKE_PROJECT_VERSION}")' \
+                     "set(IONC_FULL_VERSION \"$(cat ion-c/.nixpkgs-patching-IONC_FULL_VERSION.txt)\")"
   '';
 
-  build-system = [ setuptools ];
+  build-system = [
+    setuptools
+  ];
+
+  dontUseCmakeConfigure = true; # CMake invoked by install.py
+
+  # Can't use cmakeFlags since we do not control invocation of cmake.
+  # But build-release.sh in ion-c is sensitive to this env variable.
+  env.CMAKE_FLAGS = "-DCMAKE_SKIP_BUILD_RPATH=ON";
+
+  nativeBuildInputs = [
+    cmake
+  ];
 
   dependencies = [
     jsonconversion
@@ -55,7 +102,10 @@ buildPythonPackage rec {
     "tests/test_benchmark_cli.py"
   ];
 
-  pythonImportsCheck = [ "amazon.ion" ];
+  pythonImportsCheck = [
+    "amazon.ion"
+    "amazon.ion.ionc" # C extension module for speedup
+  ];
 
   meta = with lib; {
     description = "Python implementation of Amazon Ion";
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index eb44f2fd32d3..a0a644fbf022 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -656,7 +656,7 @@ self: super: with self; {
 
   amarna = callPackage ../development/python-modules/amarna { };
 
-  amazon-ion = callPackage ../development/python-modules/amazon-ion { };
+  amazon-ion = callPackage ../development/python-modules/amazon-ion { inherit (pkgs) cmake; };
 
   amberelectric = callPackage ../development/python-modules/amberelectric { };