fix: parsing setup.py error if it outputs to stdout (#1998)

news/1995.bugfix.md

@@ -0,0 +1 @@
+Fix an error parsing `setup.py` if it prints something to stdout.

src/pdm/models/in_process/__init__.py

@@ -8,6 +8,7 @@
 import json
 import os
 import subprocess
+import tempfile
 from typing import Any, Generator
 
 from pdm.compat import resources_path
@@ -47,5 +48,8 @@ def get_pep508_environment(executable: str) -> dict[str, str]:
 def parse_setup_py(executable: str, path: str) -> dict[str, Any]:
     """Parse setup.py and return the kwargs"""
     with _in_process_script("parse_setup.py") as script:
-        cmd = [executable, "-Es", script, path]
-        return json.loads(subprocess.check_output(cmd))
+        _, outfile = tempfile.mkstemp(suffix=".json")
+        cmd = [executable, "-Es", script, path, outfile]
+        subprocess.check_call(cmd)
+        with open(outfile, "rb") as fp:
+            return json.load(fp)

src/pdm/models/in_process/parse_setup.py

@@ -199,7 +199,13 @@ def parse_setup(path: str) -> Dict[str, Any]:
     return parsed
 
 
+def json_default(o):
+    return "<unserializable object>"
+
+
 if __name__ == "__main__":
     import json
 
-    print(json.dumps(parse_setup(sys.argv[1])))
+    outfile = sys.argv[2]
+    with open(outfile, "w") as f:
+        json.dump(parse_setup(sys.argv[1]), f, default=json_default)