panic("todo") when marshalling cbor tags

[dignifiedquire]

Hey,

I am trying to use the new tag functionality discussed in #7. But I have run into a beautiful panic todo.

You can see the trace below.

--- FAIL: TestBasicMarshal (0.00s)
panic: todo [recovered]
	panic: todo

goroutine 8 [running]:
testing.tRunner.func1(0xc4200b23c0)
	/usr/local/Cellar/go/1.9.1/libexec/src/testing/testing.go:711 +0x2d2
panic(0x11b56e0, 0x121abe0)
	/usr/local/Cellar/go/1.9.1/libexec/src/runtime/panic.go:491 +0x283
github.com/polydawn/refmt/obj._yieldMarshalMachinePtr(0xc4200c52d0, 0xc420076390, 0xc4200763c0, 0x12e8a60, 0x11d88e0, 0x10, 0x11c2a60)
	/Users/dignifiedquire/.go/src/github.com/polydawn/refmt/obj/marshalSlab.go:141 +0x718
github.com/polydawn/refmt/obj.(*marshalSlab).requisitionMachine(0xc420082a50, 0x12e8a60, 0x11d88e0, 0x12e8a60, 0x11e74a0)
	/Users/dignifiedquire/.go/src/github.com/polydawn/refmt/obj/marshalSlab.go:60 +0x179
github.com/polydawn/refmt/obj.(*marshalMachineWildcard).Reset(0xc4200c51a8, 0xc420082a50, 0x11c2a60, 0xc42004caf0, 0x94, 0x12e8a60, 0x11c2a60, 0x11b56e0, 0xc42004cae0)
	/Users/dignifiedquire/.go/src/github.com/polydawn/refmt/obj/marshalWildcard.go:26 +0xe7
github.com/polydawn/refmt/obj.(*Marshaller).Recurse(0xc420082a50, 0xc4200b6d20, 0x11c2a60, 0xc42004caf0, 0x94, 0x12e8a60, 0x11c2a60, 0x12e45a0, 0xc4200c51a8, 0x1365000, ...)
	/Users/dignifiedquire/.go/src/github.com/polydawn/refmt/obj/marshal.go:100 +0xe2
github.com/polydawn/refmt/obj.(*marshalMachineMapWildcard).Step(0xc4200c5050, 0xc420082a50, 0xc420082a50, 0xc4200b6d20, 0x0, 0x0, 0x0)
	/Users/dignifiedquire/.go/src/github.com/polydawn/refmt/obj/marshalMapWildcard.go:78 +0x1e6
github.com/polydawn/refmt/obj.(*Marshaller).Step(0xc420082a50, 0xc4200b6d20, 0x0, 0x0, 0x0)
	/Users/dignifiedquire/.go/src/github.com/polydawn/refmt/obj/marshal.go:58 +0x50
github.com/polydawn/refmt/shared.TokenPump.Run(0x12e3720, 0xc420082a50, 0x12e36a0, 0xc420082aa0, 0x0, 0xc4200c5000)
	/Users/dignifiedquire/.go/src/github.com/polydawn/refmt/shared/pump.go:31 +0x5b
github.com/polydawn/refmt/cbor.(*Marshaller).Marshal(0xc420076a80, 0x11c6aa0, 0xc420076a50, 0xc4200763c0, 0xc420076a80)
	/Users/dignifiedquire/.go/src/github.com/polydawn/refmt/cbor/cborHelpers.go:54 +0x83
github.com/polydawn/refmt/cbor.MarshalAtlased(0x11c6aa0, 0xc420076a50, 0xc420076390, 0xc4200763c0, 0x10b6c81, 0xc4200a0000, 0xc420010700, 0x34, 0x40)
	/Users/dignifiedquire/.go/src/github.com/polydawn/refmt/cbor/cborHelpers.go:39 +0x81
github.com/ipfs/go-ipld-cbor.DumpObject(0x11c6aa0, 0xc420076a50, 0xc4200a0000, 0x0, 0x0, 0xc420048e08, 0x10b6d32)
	/Users/dignifiedquire/.go/src/github.com/ipfs/go-ipld-cbor/node.go:424 +0x51
github.com/ipfs/go-ipld-cbor.WrapObject(0x11c6aa0, 0xc420076a50, 0x12, 0xffffffffffffffff, 0x1, 0x34, 0x0)
	/Users/dignifiedquire/.go/src/github.com/ipfs/go-ipld-cbor/node.go:165 +0x4d
github.com/ipfs/go-ipld-cbor.TestBasicMarshal(0xc4200b23c0)
	/Users/dignifiedquire/.go/src/github.com/ipfs/go-ipld-cbor/node_test.go:84 +0x2a3
testing.tRunner(0xc4200b23c0, 0x12043f0)
	/usr/local/Cellar/go/1.9.1/libexec/src/testing/testing.go:746 +0xd0
created by testing.(*T).Run
	/usr/local/Cellar/go/1.9.1/libexec/src/testing/testing.go:789 +0x2de

The

• test is here
• atlas is here
• marshal call is here
• the branch is https://github.com/ipfs/go-ipld-cbor/blob/refmt

From what I gathered this seems to come from here: https://github.com/polydawn/refmt/blob/master/obj/marshalSlab.go#L141 but I am not sure if this is something I should fix in my code or this needs to be fixed in the library.

[warpfork]

It is indeed a TODO for refmt :)

This path is hit when marshalling traverses to struct value of a type which hasn't had explicit configuration in the atlas. If you add another atlas.BuildEntry() /*...*/ for whatever type is missing, you'll be back on the happy path.

The future plan is to make additional options to the overall atlas build for whether or not to silently try to autogenerate configuration for structs when they're encountered. This would be equivalent to what the stdlib json packages do. In refmt I think we'll probably keep that to off by default, based on the theology that explicit is better than implicit (and personally, mostly because I'm really frustrated whenever I find an error from fmt.Errorf has been quietly serialized to a useless json {}), but the option should be supported.

Of course, the way this currently errors is more aggressively than it should, and the fact that the message doesn't really point you in the right direction is a pretty gross bug, and I'll try to at least improve those messages ASAP.

[warpfork]

Error message should be more useful as of that commit on master ^

[dignifiedquire]

Thank you 👍

Interestingly enough the error went away when I switched to using the non pointer version of my struct, without changing anything else in the atlas.

[warpfork]

Ohhh. Hm, that's a thing that should have its own checks. The object used as the "type reference" in atlas.BuildEntry(thingy{}) is expected to be a bare object, yes. I opened #11 to remind myself of this in the morning (getting a bit late here).

[warpfork]

GC/closing because #11 covers it.