Stack branch type checking of call_indirect

[binji]

Type checking of call_indirect on the stack branch is currently defined as:

  | CallIndirect x ->
    let FuncType (ins, out) = type_ c.types x in
    (ins @ [I32Type]) --> Stack out

Which means the table index comes last (i.e. is on the top of the stack), is that correct? This is inconsistent with the binary format 0xb where the function index is first. Though I've also noticed that this isn't specified in the binary format design docs: https://github.com/WebAssembly/design/blob/master/BinaryEncoding.md#basic-operators-described-here.

Is this also changing with binary_0xc, or is this a bug?

[kripken]

I believe this is an intentional change, yes, to make call_indirect more like select, br_table, etc. The change showed up in b155302 together with test changes for it.

[binji]

OK, that makes sense, kind of.

[rossberg]

Yes, we decided to make this change for 0xC. Somebody still has to write the PR, though. I can do that.

[rossberg]

See WebAssembly/design#758.

[rossberg]

Design repo has been updated.