Quick and dirty PR to suppress warning when building / running compiler that says:
```rust
warning: variant is never constructed: `Zig8`
--> compiler/gen_wasm/src/layout.rs:143:5
|
143 | Zig8,
| ^^^^
|
= note: `#[warn(dead_code)]` on by default
```
I'm guessing that the `Zig8` case will be used at some point, so outright deleting the case seemed hasteful to me.
Closes#2535
See the referenced issue for longer discussion - here's the synopsis.
Consider this program
```
app "test" provides [ nums ] to "./platform"
alpha = { a: 1, b: 2 }
nums : List U8
nums =
[
alpha.a,
alpha.b,
]
```
Here's its IR:
```
procedure : `#UserApp.alpha` {I64, U8}
procedure = `#UserApp.alpha` ():
let `#UserApp.5` : Builtin(Int(I64)) = 1i64;
let `#UserApp.6` : Builtin(Int(U8)) = 2i64;
let `#UserApp.4` : Struct([Builtin(Int(I64)), Builtin(Int(U8))]) = Struct {`#UserApp.5`, `#UserApp.6`};
ret `#UserApp.4`;
procedure : `#UserApp.nums` List U8
procedure = `#UserApp.nums` ():
let `#UserApp.7` : Struct([Builtin(Int(I64)), Builtin(Int(U8))]) = CallByName `#UserApp.alpha`;
let `#UserApp.1` : Builtin(Int(U8)) = StructAtIndex 1 `#UserApp.7`;
let `#UserApp.3` : Struct([Builtin(Int(I64)), Builtin(Int(U8))]) = CallByName `#UserApp.alpha`;
let `#UserApp.2` : Builtin(Int(U8)) = StructAtIndex 1 `#UserApp.3`;
let `#UserApp.0` : Builtin(List(Builtin(Int(U8)))) = Array [`#UserApp.1`, `#UserApp.2`];
ret `#UserApp.0`;
```
What's happening is that we need to specialize `alpha` twice - once for the
type of a narrowed to a U8, another time for the type of b narrowed to a U8.
We do the specialization for alpha.b first - record fields are sorted by
layout, so we generate a record of type {i64, u8}. But then we go to
specialize alpha.a, but this has the same layout - {i64, u8} - so we reuse
the existing one! So (at least for records), we need to include record field
order associated with the sorted layout fields, so that we don't reuse
monomorphizations like this incorrectly!
