From fa417fe3f70bc446b3bb84b6028d00be954cf10d Mon Sep 17 00:00:00 2001
From: Kirill Elagin <kirelagin@gmail.com>
Date: Mon, 7 Jul 2025 20:34:48 +0200
Subject: [PATCH] pylibfdt: Use the correct Python for tests
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By default, Meson will find the version of Python that it itself is
using, i.e. the default one in Nixpkgs.
However, when building libfdt for other Python package sets, we need to
make sure we match the version of the Python used for tests – otherwise
the interpreter will not find the compiled module.

Tweak meson.build to always use the Python interpreter that was passed
to the expression, rather than the default one.
---
 pkgs/by-name/dt/dtc/package.nix       | 11 ++++++++++-
 pkgs/by-name/dt/dtc/python-path.patch | 12 ++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 pkgs/by-name/dt/dtc/python-path.patch

diff --git a/pkgs/by-name/dt/dtc/package.nix b/pkgs/by-name/dt/dtc/package.nix
index 527ffe873bb2..ed41487a81b2 100644
--- a/pkgs/by-name/dt/dtc/package.nix
+++ b/pkgs/by-name/dt/dtc/package.nix
@@ -11,6 +11,7 @@
   which,
   pythonSupport ? false,
   python ? null,
+  replaceVars,
   swig,
   libyaml,
 }:
@@ -38,7 +39,15 @@ stdenv.mkDerivation (finalAttrs: {
       url = "https://github.com/dgibson/dtc/commit/ce1d8588880aecd7af264e422a16a8b33617cef7.patch";
       hash = "sha256-t1CxKnbCXUArtVcniAIdNvahOGXPbYhPCZiTynGLvfo=";
     })
-  ];
+  ]
+  ++
+    lib.optional pythonSupport
+      # Make Meson use our Python version, not the one it was built with itself
+      (
+        replaceVars ./python-path.patch {
+          python_bin = lib.getExe python;
+        }
+      );
 
   env.SETUPTOOLS_SCM_PRETEND_VERSION = finalAttrs.version;
 
diff --git a/pkgs/by-name/dt/dtc/python-path.patch b/pkgs/by-name/dt/dtc/python-path.patch
new file mode 100644
index 000000000000..6163dc0b294d
--- /dev/null
+++ b/pkgs/by-name/dt/dtc/python-path.patch
@@ -0,0 +1,12 @@
+diff --git a/meson.build b/meson.build
+index 310699f..4e2b8a4 100644
+--- a/meson.build
++++ b/meson.build
+@@ -48,7 +48,7 @@ if not valgrind.found()
+ endif
+ 
+ py = import('python')
+-py = py.find_installation(required: get_option('python'))
++py = py.find_installation('@python_bin@', required: get_option('python'))
+ swig = find_program('swig', required: get_option('python'))
+ pylibfdt_enabled = not meson.is_cross_build() and py.found() and swig.found() ? true : false