FFlags
New functions, libraries and language features sit behind FFlags while their design settles. A host turns a flag on before it creates the VM, and every flag is off until it does. The Standard Library reference names the flag each entry needs.
Which flags are on
Luwu's command-line tools turn on every flag whose name starts with Luau or Luwu and leave the ones starting with Debug off. Runtimes choose their own: seal, for example, turns on the flags its scripts use, some Debug flags included.
MAINTAINERS.md in the Luwu repository lists every Luwu FFlag with the RFC it belongs to.
Stability
The reference marks each Luwu addition with how settled it is:
stable: available in luwu/master, not gated by an FFlag and not expected to change.flagged: available in luwu/integration and gated by an FFlag. We anticipate this feature to be released and enabled by default in 0.1.0.experimental: available in luwu/integration; this feature is unstable and may change without a semver bump. Its flag starts withDebugLuwuorDebugLuau.
Setting a flag
A host written in C or C++ sets a flag before it creates the state:
luau_setfflag("LuwuTableDrop", 1);A Rust host using mluau calls Lua::set_fflag:
mluau::Lua::set_fflag("LuwuTableDrop", true)?;