Panic message not printed correctly

[tiziano88]

The error currently shows as

2020-01-16 17:03:46,825 ERROR [oak] panic occurred in file 'abitest/tests/src/tests.rs' at line 76: <UNKNOWN MESSAGE>

To reproduce, add assert_eq!(1, 2) to some function under test, e.g.:

oak/examples/abitest/tests/src/tests.rs

Lines 55 to 88 in f317c1c

	#[test]
	#[serial(node_test)]
	fn test_abi() {
	// Initialize the test logger first, so logging gets redirected to simple_logger.
	// (A subsequent attempt to use the oak_log crate will fail.)
	oak_tests::init_logging();
	let mut entrypoints = HashMap::new();
	let fe: oak_runtime::NodeMain = abitest_0_frontend::main;
	let be: oak_runtime::NodeMain = abitest_1_backend::main;
	entrypoints.insert(FRONTEND_CONFIG_NAME.to_string(), fe);
	entrypoints.insert(BACKEND_CONFIG_NAME.to_string(), be);
	assert_eq!(Some(()), oak_tests::start(test_config(), entrypoints));
	let mut req = ABITestRequest::new();
	// Skip raw tests (which use invalid memory addresses etc.).
	req.exclude = "Raw".to_string();
	let result: grpc::Result<ABITestResponse> =
	oak_tests::inject_grpc_request("/oak.examples.abitest.OakABITestService/RunTests", req);
	assert_matches!(result, Ok(_));
	assert_eq!(OakStatus::ERR_TERMINATED, oak_tests::stop());
	for result in result.unwrap().get_results() {
	info!(
	"[ {} ] {}",
	if result.success { " OK " } else { "FAIL" },
	result.name
	);
	if !result.success {
	error!("Failure details: {}", result.details);
	}
	assert_eq!(true, result.success);
	}
	}

and then run the tests locally with cargo test.

Note that panic!("xxx") seems to show up fine instead, not sure if assert_eq is using a different mechanism behind the scenes.

I also noticed similar errors a few times when running compiled code on the Oak Runtime, but I don't have reproducibility steps for that yet.

@conradgrobler could you take a look? @daviddrysdale may have some thoughts about it too

[daviddrysdale]

The <UNKNOWN MESSAGE> indicates that the panic hook that we register in oak::set_panic_hook has been unable to retrieve the payload from the PanicInfo. Dunno (yet) why that should happen for a panic! generated from the assert_eq! macro but not from an unadorned panic!.

[daviddrysdale]

The panic details are also lost if a plain panic! has arguments (e.g. panic!("some {:?} thing", 1);). Maybe it's a Rust bug/limitation?

[daviddrysdale]

rust-lang/rust#66745 looks potentially relevant.

[conradgrobler]

Changing the custom panic hook to handle the downcasting in a way that is more similar to the default hook should resolve it.

https://github.com/rust-lang/rust/blob/7d761fe0462ba0f671a237d0bb35e3579b8ba0e8/src/libstd/panicking.rs#L171-L177

[conradgrobler]

Resolved by #485