FastFlag namespace FFlag:: — static (non-dynamic) bool flags. Definitions
from LUAU_FASTFLAGVARIABLE(...) across this crate’s sources are collected
here so C++ reads FFlag::Name map to crate::FFlag::Name.get(). (Rust
modules are not open like C++ namespaces, so the per-crate namespace module
is the aggregation point — see crate::macros::luau_fastflagvariable.)
Static int FastFlags, mirroring FFlag. C++ collects every
LUAU_FASTINTVARIABLE(...) into namespace FInt; Rust modules aren’t open,
so the consumers’ flags are gathered here. Read as FInt::Flag.get().
AST RTTI mechanism — the faithful Rust analog of Luau’s
AstRtti<T>::value / LUAU_RTTI(Class) / AstNode::is<T>() / as<T>().
Reference: luau/Ast/include/Luau/Ast.h (the AstNode base + the
LUAU_RTTI macro).