Fix PEP 768 code injection SyntaxError when temp path contains backslashes

src/debugpy/server/cli.py

@@ -465,7 +465,7 @@ def attach_to_pid():
                 )
                 tmp_file.write(python_code.encode())
                 tmp_file.write(
-                    """import os;os.remove("{tmp_file_path}");""".format(
+                    """import os;os.remove({tmp_file_path!r});""".format(
                         tmp_file_path=tmp_file_path
                     ).encode()
                 )

tests/debugpy/server/test_cli.py

@@ -248,3 +248,64 @@ def test_script_parent_pid_with_listen_failure(cli):
         cli(["--listen", "8888", "--parent-session-pid", "1234", "spam.py"])
 
     assert "--parent-session-pid requires --connect" in str(ex.value)
+
+
+def test_pep_768_remote_exec_called_with_backslash_path():
+    """Test that attach_to_pid() calls sys.remote_exec and writes valid Python
+    to the temp file even when the temp path contains backslashes (Windows)."""
+    import contextlib
+    from debugpy.server import cli
+
+    mock_windows_tmp_path = r"C:\Users\test\AppData\Local\Temp\tmp0_vuee4s"
+    pid = os.getpid()
+
+    # A fake file object that captures writes via a side_effect list.
+    # Using MagicMock avoids the BytesIO.close() issue where getvalue()
+    # raises ValueError on a closed buffer.
+    written_chunks = []
+    fake_file = mock.MagicMock()
+    fake_file.name = mock_windows_tmp_path
+    fake_file.write.side_effect = written_chunks.append
+
+    fake_file_cm = mock.MagicMock()
+    fake_file_cm.__enter__ = mock.Mock(return_value=fake_file)
+    fake_file_cm.__exit__ = mock.Mock(return_value=False)
+
+    # Configure cli.options with the minimum fields attach_to_pid() needs.
+    original_options = {
+        attr: getattr(cli.options, attr)
+        for attr in ("mode", "address", "wait_for_client", "log_to",
+                     "adapter_access_token", "disable_sys_remote_exec", "target")
+    }
+    try:
+        cli.options.mode = "connect"
+        cli.options.address = ("127.0.0.1", 5678)
+        cli.options.wait_for_client = False
+        cli.options.log_to = None
+        cli.options.adapter_access_token = None
+        cli.options.disable_sys_remote_exec = False
+        cli.options.target = pid
+
+        with contextlib.ExitStack() as stack:
+            stack.enter_context(
+                mock.patch("tempfile.NamedTemporaryFile", return_value=fake_file_cm)
+            )
+            mock_remote_exec = stack.enter_context(
+                mock.patch.object(sys, "remote_exec", create=True)
+            )
+            cli.attach_to_pid()
+
+        # sys.remote_exec must have been called with the original (backslash) path
+        # because that is the actual path created on disk.
+        mock_remote_exec.assert_called_once_with(pid, mock_windows_tmp_path)
+
+        # The Python code written to the temp file must be syntactically valid.
+        injected_code = b"".join(written_chunks).decode()
+        compile(injected_code, "<string>", "exec")
+
+        # The os.remove() call inside the injected code must use the repr of the path
+        # so that it is a valid Python string literal on all platforms.
+        assert "import os;os.remove({});".format(repr(mock_windows_tmp_path)) in injected_code
+    finally:
+        for attr, value in original_options.items():
+            setattr(cli.options, attr, value)