Static arrays.

[otrho]

Here's an initial implementation of static arrays. This has taken me a while and it's arguably not yet finished but I want to get this going sooner rather than later.

The basics work -- declaring both [1, 2, 3] or [false; 3] style initialisers, indexing with a u64 index, type checking everywhere, arrays of arrays, arrays of structs, etc.

But there's still some work:

• Parsing of arrays of aggregates is a bit lacking, it currently requires a[0][1] to be (a[0])[1].
• The Index trait (or at least my_type.index(arg) for my_type[arg]) is invoked but not at all implemented yet.
• No mutation at all. It doesn't compile if you try.
• Code generation is a bit ordinary:
  • Unnecessary copies may be made during initialisation.
  • Element initialisation is done one by one, even when a MCP could do it all at once.
  • Every single index access is bounds checked (and will RVRT on failure) whether it needs it or not.
  • While testing large arrays the tests just ran out of gas. They're too expensive.

The first one could be fixed fairly easily, I just wanted to get on with it, working with Pest sucks.

The next two are non-trivial, we can tackle them when they're needed, which maybe now, IDK.

The code generation can be fixed with The Magic Of IR 🪄 -- as I was writing all the code gen code I was thinking, 'dammit, we're going to have to write all this again, except better'. But that's OK. The point of IR is to make that sort of thing relatively easy.

[adlerjohn]

Could you not increase the gas used in tests? This is outside of consensus, so there's no real downside to putting an insane gas limit.

[otrho]

Could you not increase the gas used in tests? This is outside of consensus, so there's no real downside to putting an insane gas limit.

Yeah, though not on a per test basis, I think. But we could... I'm just saying that right now very large (MBs) arrays are very expensive, even just to instantiate. Rather than initialise every element individually for [val; count] arrays we could MCP from the data section. Or something.

[sezna]

Yeah that MCP optimization makes sense. But either way we can basically use infinite gas for tests right now if we'd like.

[sezna]

LGTM, will re-approve after the latest version of master is merged in