Use host sysconfig for PYO3 cross lib dir

Adjust cross-build sysconfig handling for pyo3 on Apple platforms. Add a host_sysconfig attribute to CrossVEnv and set PYO3_CROSS_LIB_DIR to the host_sysconfig.parent (the directory containing _sysconfigdata__*.py), falling back to <prefix>/lib when host_sysconfig is unavailable. Also comment out the recipe-level _PYTHON_SYSCONFIGDATA_NAME script_env entry. These changes address newer Apple support layouts that place sysconfig data outside the venv prefix/lib.

Author: FeodorFitsner

recipes/pydantic-core/meta.yaml

@@ -2,6 +2,6 @@ package:
   name: pydantic-core
   version: 2.33.2
 
-build:
-  script_env:
-    _PYTHON_SYSCONFIGDATA_NAME: '{sysconfigdata_name}'
+# build:
+#   script_env:
+#     _PYTHON_SYSCONFIGDATA_NAME: '{sysconfigdata_name}'

src/forge/build.py

@@ -378,8 +378,14 @@ def compile_env(self, **kwargs) -> dict[str, str]:
             "PYO3_CROSS_PYTHON_VERSION": self.cross_venv.sysconfig_data[
                 "py_version_short"
             ],
-            "PYO3_CROSS_LIB_DIR": "{}/lib".format(
-                self.cross_venv.sysconfig_data["prefix"]
+            # pyo3 expects a directory containing _sysconfigdata__*.py.
+            # Newer Apple support layouts place this outside prefix/lib.
+            "PYO3_CROSS_LIB_DIR": str(
+                (
+                    self.cross_venv.host_sysconfig.parent
+                    if self.cross_venv.host_sysconfig is not None
+                    else Path(self.cross_venv.sysconfig_data["prefix"]) / "lib"
+                )
             ),
         }
         env.update(kwargs)

src/forge/cross.py

@@ -105,6 +105,7 @@ def __init__(self, sdk, sdk_version, arch):
         self._scheme_paths = None
         self._install_root = None
         self._sdk_root = None
+        self.host_sysconfig = None
 
     def __str__(self):
         return self.venv_name
@@ -315,6 +316,8 @@ def create(
             )
             self.sysconfigdata_name = host_sysconfig.stem
 
+        self.host_sysconfig = host_sysconfig
+
         if self.host_os != "iOS" and not host_sysconfig.is_file():
             raise RuntimeError(f"Can't find host sysconfig {host_sysconfig}")