gh-144533: Use pybuilddir.txt to find _sysconfigdata for WASI

Author: therohityadav

Misc/NEWS.d/next/Build/2026-02-06-13-49-09.gh-issue-144533.1k4jaE.rst

@@ -0,0 +1 @@
+Use `pybuilddir.txt` to find `_sysconfigdata` for the WASI build script.

Platforms/WASI/__main__.py

@@ -324,9 +324,16 @@ def configure_wasi_python(context, working_dir):
     )
     lib_dir = os.fsdecode(lib_dirs[0])
     python_version = lib_dir.rpartition("-")[-1]
-    sysconfig_data_dir = (
-        f"{wasi_build_dir}/build/lib.wasi-wasm32-{python_version}"
-    )
+
+    pybuilddir = working_dir / "pybuilddir.txt"
+    if pybuilddir.is_file():
+        with pybuilddir.open("r", encoding="utf-8") as f:
+            sysconfig_data_dir = f"{wasi_build_dir}/{f.read().strip()}"
+    else:
+        # Fallback if the build hasn't generated the file yet
+        sysconfig_data_dir = (
+            f"{wasi_build_dir}/build/lib.wasi-wasm32-{python_version}"
+        )
 
     # Use PYTHONPATH to include sysconfig data which must be anchored to the
     # WASI guest's `/` directory.