0.699

Hello all! Another week, another release!

Analysis

• Fixed table.clone in the old solver to ensure intersections of tables were being entirely cloned: prior only the first table in the intersection would be copied:

type FIRST = { some: string }
type SECOND = FIRST & { thing: string }
local b: SECOND
-- c's type used to be FIRST, but should be the full type of SECOND
local c = table.clone(b)

• Fixed table.clone in the old solver to be more permissive and treat a variadic return as having at least one element. This works around some unfortunate behavior in the old solver version of nonstrict mode, see:

-- A.luau
--!nonstrict
return function()
    return {}
end
-- B.luau
local A = require("A")
-- This line would previously error as `A` has type `() -> (...any)`, so
-- we might not be providing enough parameters to `table.clone`.
local _ = table.clone(A())

• Fixed a bug in the new solver where error suppression was not kicking in for indexing, as in:

local function f(value: any)
    if value ~= nil then
        for k = 1, #value do
            -- Previously this would error, claiming you cannot index into a `*error-type* | ~nil`
            local _ = value[k]
        end
    end
end

• Fix the getmetatable type function in the new solver to accept *error-type* and table as valid type inputs.
• Changed how error reporting for invalid for ... in loops works: for now this may result in slightly worse error messages (see the example below), but should mean error suppression is more consistent going forward:

function my_iter(state: string, index: number)
    return state, index
end
local my_state = {}
local first_index = "first"
-- Prior we would claim `my_state` and `first_index` are of the incorrect types,
-- now we claim that `my_iter` is of the incorrect type, which can be considered
-- true, but is less helpful.
for a, b in my_iter, my_state, first_index do
end

Runtime

• Introduced lua_rawgetptagged and lua_rawsetptagged, as well as Lua 5.2+ compatibility macros lua_rawgetp and lua_rawsetp, to be able to perform lookups into tables using tagged or untagged lightuserdata without additional calls and stack manipulation. This enables a more efficient lookup way for lightuserdata keys similar to how lua_rawgetfield and lua_rawgeti avoid extra operations for their corresponding types.

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Co-authored-by: Andy Friesen afriesen@roblox.com
Co-authored-by: Annie Tang annietang@roblox.com
Co-authored-by: Ariel Weiss arielweiss@roblox.com
Co-authored-by: Hunter Goldstein hgoldstein@roblox.com
Co-authored-by: Varun Saini vsaini@roblox.com
Co-authored-by: Vyacheslav Egorov vegorov@roblox.com