Problems with JSON output

[dkcumming]

On commit 0a14cc9 of smir_pretty there are two problems we need to resolve with the output:

1. ty as id with entry for that id anywhere. We need to find what "16" connects to by looking at the code in printer.rs and the serialisation code that is upstreamed into rust (it is all just #[derive(serde)]):

                            "locals": [
                                {
                                    "mutability": "Mut",
                                    "span": 26,
                                    "ty": 16
                                },

2. Functions in the "functions" array that share the same name have a different id that in "items", should they be the same?

See

sum-to-n.smir.json

[gtrepta]

In a dbg! dump of the visited_tys in emit_smir_internal reveals lots of information. Some looks relevant to the type ids:

Ty {
    id: 16,
    kind: RigidTy(
        Int(
            I32,
        ),
    ),
},