collectgarbage("count") does not accept other values [v0.10.0 - v0.10.1]

[TokenManiac]

Hello, just today I noticed that any other option than "count" passed into collectgarbage throws the following error in versions v0.10.0 - v0.10.1:

collectgarbage("collect")

test:1: collectgarbage called with invalid option
[Stack Begin]
    Script '[C]'
    Script 'test', Line 1
[Stack End]

Expected behavior:
collectgarbage("collect" | "stop" | "restart" | "step" | "isrunning") should run without errors, as in previous versions.

Actual behavior:
The function throws an “invalid option” error for any option except "count"

This change wasn't specified in the changelog so it may just be a mistake?
Either way it may result in confusion 👍

_{p.s. thank you for maintaining this awesome project!}

[cheesycod]

This is a mlua change to block collectgarbage collect etc in sandboxed mode (Im actually the person who asked for this change too) due to the security implications of allowing user code to control the gc. This is not just me/mlua btw, it’s actually what luau itself recommends (see https://luau.org/sandbox#library) so I’d say that this change brings mlua more in line with luau’s sandboxing guidelines.

Personally, I think that lune should expose its own gc API if that’s something actually desired though

[TokenManiac]

I would say one of the strengths of lune is its flexibility (with the upcoming ffi support). I'd like to see a few options being brought back.

An approach might be an optional "unsafe" flag for power users who know exactly what they're doing, allowing options like "step" and "collect" but excluding ones like "stop" or "restart" (maybe?). Or as you've suggested an API could be introduced to keep things way safer. I'm not exactly sure.

Again, with the upcoming ffi support, having more granular GC control would definitely improve flexibility over memory.

[filiptibell]

Yeah I'm not quite sure what to do about this. Lune enables sandboxed Luau for performance reasons, and manual garbage collection, as noted, is disabled in this mode for safety.. We may be able to add back manual garbage collection in the future so I labeled this as "enhancement" for now.