Luau Files

Made a wish on a shooting star this week? 🌠 The Luau team's here to make them come true with another release! 🌌

General 🌟

• pcall and xpcall are now allowed in user-defined type functions! Resolving https://github.com/luau-lang/luau/issues/2499 and in accordance to https://github.com/luau-lang/rfcs/pull/228

Analysis ⭐️

• Improvements to quality of error messages, resolving https://github.com/luau-lang/luau/pull/2611 and https://github.com/luau-lang/luau/pull/2612

• Fixes an issue where the new solver would not infer generalized iteration:

  :::lua local function setupRootMappingMove(rootMapping) -- Prior, the new solver would infer rootMapping.RootToDescendantCountMap -- as unknown, which is clearly not correct. for root, childCount in rootMapping.RootToDescendantCountMap do string.len(root) math.abs(childCount) end end

• Fixes a refinement bug that could cause us to report any as the result of indexing into a refined table that contained a blocked type:

  :::lua const MyClass = { __index = {}, }

  type MyClass<T> = setmetatable<{ _t: T }, typeof(MyClass)>

  type MyFunction<T> = (class: MyClass<T>) -> () | { fn: ((class: MyClass<T>) -> ())?, }

  function MyClass.__index.call<T>(self: MyClass<T>, f: MyFunction<T>): () if type(f) == "function" then f(self) elseif f.fn then -- Prior, we would infer this to be any, which is incorrect. const thevalue = f.fn local _ = thevalue f.fn(self) end end

• Wrap only function return types in AstTypeGroup for unions and intersections, so (string) -> ((string) & (number) -> (number)) is improved to (string) -> (string) & (number) -> (number)

• Fixes a bug in the New Type Solver that reports an incorrect error on the wrong argument for function calls
• Fix negated integer literals reporting a type error by @green-real in https://github.com/luau-lang/luau/pull/2615

Runtime ✨

• Fix missing links in luaC_enumheap
• Luau CodeGen: flow known tag info in and through fallback blocks

And thanks to our contributors as always!

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: Ilya Rezvov irezvov@roblox.com Co-authored-by: Phil Pizlo fpizlo@roblox.com Co-authored-by: Sora Kanosue skanosue@roblox.com Co-authored-by: Thomas Schollenberger tschollenberger@roblox.com Co-authored-by: Vighnesh Vijay vvijay@roblox.com Co-authored-by: Vyacheslav Egorov vegorov@roblox.com

Full Changelog: https://github.com/luau-lang/luau/compare/0.733...0.734