dtc: fix python 3.10 compatibility

pkgs/development/compilers/dtc/default.nix

@@ -1,5 +1,15 @@
-{ stdenv, lib, fetchgit, flex, bison, pkg-config, which
-, pythonSupport ? false, python ? null, swig, libyaml
+{ stdenv
+, lib
+, fetchgit
+, fetchpatch
+, flex
+, bison
+, pkg-config
+, which
+, pythonSupport ? false
+, python ? null
+, swig
+, libyaml
 }:
 
 stdenv.mkDerivation rec {
@@ -12,8 +22,17 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-gx9LG3U9etWhPxm7Ox7rOu9X5272qGeHqZtOe68zFs4=";
   };
 
+  patches = [
+    # fix python 3.10 compatibility
+    # based on without requiring the setup.py rework
+    # https://git.kernel.org/pub/scm/utils/dtc/dtc.git/commit/?id=383e148b70a47ab15f97a19bb999d54f9c3e810f
+    ./python-3.10.patch
+  ];
+
+  nativeBuildInputs = [ flex bison pkg-config which ]
+    ++ lib.optionals pythonSupport [ python swig ];
+
   buildInputs = [ libyaml ];
-  nativeBuildInputs = [ flex bison pkg-config which ] ++ lib.optionals pythonSupport [ python swig ];
 
   postPatch = ''
     patchShebangs pylibfdt/

pkgs/development/compilers/dtc/python-3.10.patch

@@ -0,0 +1,28 @@
+diff --git a/pylibfdt/libfdt.i b/pylibfdt/libfdt.i
+index 51ee801..075ef70 100644
+--- a/pylibfdt/libfdt.i
++++ b/pylibfdt/libfdt.i
+@@ -1044,9 +1044,9 @@ typedef uint32_t fdt32_t;
+ 		$result = Py_None;
+ 	else
+         %#if PY_VERSION_HEX >= 0x03000000
+-            $result = Py_BuildValue("y#", $1, *arg4);
++            $result = Py_BuildValue("y#", $1, (Py_ssize_t)*arg4);
+         %#else
+-            $result = Py_BuildValue("s#", $1, *arg4);
++            $result = Py_BuildValue("s#", $1, (Py_ssize_t)*arg4);
+         %#endif
+ }
+ 
+diff --git a/pylibfdt/setup.py b/pylibfdt/setup.py
+index ef40f15..81e161a 100755
+--- a/pylibfdt/setup.py
++++ b/pylibfdt/setup.py
+@@ -42,6 +42,7 @@ def get_version():
+ libfdt_module = Extension(
+     '_libfdt',
+     sources=[os.path.join(srcdir, 'libfdt.i')],
++    define_macros=[('PY_SSIZE_T_CLEAN', None)],
+     include_dirs=[os.path.join(srcdir, '../libfdt')],
+     libraries=['fdt'],
+     library_dirs=[os.path.join(top_builddir, 'libfdt')],