fix(cuda.pathfinder): preserve missing-library errors

cuda_pathfinder/cuda/pathfinder/_static_libs/find_bitcode_lib.py

@@ -71,8 +71,13 @@ def _no_such_file_in_dir(directory: Path, filename: str, error_messages: list[st
     error_messages.append(f"No such file: {directory / filename}")
     if directory.is_dir():
         attachments.append(f'  listdir("{directory}"):')
-        for node in sorted(node_path.name for node_path in directory.iterdir()):
-            attachments.append(f"    {node}")
+        try:
+            entries = sorted(node_path.name for node_path in directory.iterdir())
+        except OSError as exc:
+            attachments.append(f"    {type(exc).__name__}: {exc}")
+        else:
+            for node in entries:
+                attachments.append(f"    {node}")
     else:
         attachments.append(f'  Directory does not exist: "{directory}"')
 

cuda_pathfinder/cuda/pathfinder/_static_libs/find_static_lib.py

@@ -67,8 +67,13 @@ def _no_such_file_in_dir(directory: Path, filename: str, error_messages: list[st
     error_messages.append(f"No such file: {directory / filename}")
     if directory.is_dir():
         attachments.append(f'  listdir("{directory}"):')
-        for node in sorted(node_path.name for node_path in directory.iterdir()):
-            attachments.append(f"    {node}")
+        try:
+            entries = sorted(node_path.name for node_path in directory.iterdir())
+        except OSError as exc:
+            attachments.append(f"    {type(exc).__name__}: {exc}")
+        else:
+            for node in entries:
+                attachments.append(f"    {node}")
     else:
         attachments.append(f'  Directory does not exist: "{directory}"')
 

cuda_pathfinder/tests/test_missing_lib_diagnostics.py

@@ -0,0 +1,113 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import os
+from pathlib import Path
+
+import pytest
+
+import cuda.pathfinder._static_libs.find_bitcode_lib as bitcode_module
+import cuda.pathfinder._static_libs.find_static_lib as static_module
+from cuda.pathfinder._utils.env_vars import get_cuda_path_or_home
+
+
+@pytest.fixture(autouse=True)
+def clear_lookup_caches():
+    get_cuda_path_or_home.cache_clear()
+    bitcode_module.find_bitcode_lib.cache_clear()
+    static_module.find_static_lib.cache_clear()
+    yield
+    get_cuda_path_or_home.cache_clear()
+    bitcode_module.find_bitcode_lib.cache_clear()
+    static_module.find_static_lib.cache_clear()
+
+
+def _missing_lookup(monkeypatch, tmp_path, kind, api):
+    monkeypatch.delenv("CUDA_PATH", raising=False)
+    monkeypatch.delenv("CONDA_PREFIX", raising=False)
+    root = tmp_path / "toolkit"
+    monkeypatch.setenv("CUDA_HOME", str(root))
+    if kind == "bitcode":
+        module = bitcode_module
+        name = "device"
+        info = module._SUPPORTED_BITCODE_LIBS_INFO[name]
+        relative_dir = info["rel_path"]
+        expected_error = module.BitcodeLibNotFoundError
+        lookup = module.find_bitcode_lib if api == "find" else module.locate_bitcode_lib
+    else:
+        module = static_module
+        name = "cudadevrt"
+        info = module._SUPPORTED_STATIC_LIBS_INFO[name]
+        relative_dir = info["ctk_rel_paths"][0]
+        expected_error = module.StaticLibNotFoundError
+        lookup = module.find_static_lib if api == "find" else module.locate_static_lib
+
+    monkeypatch.setattr(module, "find_sub_dirs_all_sitepackages", lambda _sub_dir: [])
+    directory = root / relative_dir
+    directory.mkdir(parents=True)
+    return directory, info["filename"], lookup, name, expected_error
+
+
+@pytest.mark.parametrize("kind", ("bitcode", "static"))
+@pytest.mark.parametrize("api", ("find", "locate"))
+@pytest.mark.parametrize("error_type", (PermissionError, FileNotFoundError))
+@pytest.mark.agent_authored(model="gpt-6")
+def test_listing_os_error_preserves_not_found_exception(monkeypatch, tmp_path, kind, api, error_type):
+    directory, filename, lookup, name, expected_error = _missing_lookup(monkeypatch, tmp_path, kind, api)
+    real_iterdir = Path.iterdir
+
+    def failing_iterdir(path):
+        if path == directory:
+            raise error_type("simulated listing failure")
+        return real_iterdir(path)
+
+    monkeypatch.setattr(Path, "iterdir", failing_iterdir)
+    with pytest.raises(expected_error) as exc_info:
+        lookup(name)
+
+    message = str(exc_info.value)
+    assert str(directory / filename) in message
+    assert error_type.__name__ in message
+    assert "simulated listing failure" in message
+
+
+@pytest.mark.skipif(os.name == "nt", reason="POSIX directory permission bits")
+@pytest.mark.parametrize("kind", ("bitcode", "static"))
+@pytest.mark.parametrize("api", ("find", "locate"))
+@pytest.mark.agent_authored(model="gpt-6")
+def test_unreadable_directory_preserves_not_found_exception(monkeypatch, tmp_path, kind, api):
+    directory, filename, lookup, name, expected_error = _missing_lookup(monkeypatch, tmp_path, kind, api)
+    directory.chmod(0o111)
+    try:
+        try:
+            next(directory.iterdir(), None)
+        except PermissionError:
+            pass
+        else:
+            pytest.skip("the current user can list a directory without read permission")
+
+        with pytest.raises(expected_error) as exc_info:
+            lookup(name)
+
+        message = str(exc_info.value)
+        assert str(directory / filename) in message
+        assert "PermissionError" in message
+    finally:
+        directory.chmod(0o700)
+
+
+@pytest.mark.parametrize("kind", ("bitcode", "static"))
+@pytest.mark.agent_authored(model="gpt-6")
+def test_non_os_listing_error_is_not_suppressed(monkeypatch, tmp_path, kind):
+    directory, _filename, lookup, name, _expected_error = _missing_lookup(monkeypatch, tmp_path, kind, "locate")
+    real_iterdir = Path.iterdir
+
+    def failing_iterdir(path):
+        if path == directory:
+            raise RuntimeError("unexpected listing failure")
+        return real_iterdir(path)
+
+    monkeypatch.setattr(Path, "iterdir", failing_iterdir)
+    with pytest.raises(RuntimeError, match="unexpected listing failure"):
+        lookup(name)