Zero initialize locals

[Rerumu]

WebAssembly expects locals (but not parameters) in a function body to be initialized to 0 by default. wasm2lua currently initializes them as nil which causes code that relies on this invariant to break.

This minimal example is valid and should return 0, but returns nil instead.

[SwadicalRag]

Thank you

[SwadicalRag]

Actually, hold on, this should have already worked prior to the fix since wasm2lua checks if variables are accessed before they are initialised and auto-initialises them to 0

[SwadicalRag]

wasm2lua@0.8.8

wasm2lua@0.8.9

[SwadicalRag]

I'll rollback the code. 0.8.9 will initialise all non-parametric locals to 0, but it does so at the cost of increased code size.

This is what happens when I try and go edit code I haven't touched in years

[Rerumu]

That is interesting; the issue is an uninitialized variable for sure but possibly because of a buggy heuristic instead. The repro I provided is the same one I used when I found the same issue on a similar project, my bad for not testing if that one specifically caused it.

This is the larger repro I have confirmed the bug in. With this initialization code:

local function put_char(_) end

local module = require('translated')

module.imports.env = {put_char = put_char}
module.exports.main(0, 0)

[SwadicalRag]

I'll have a poke around and see what I find