0.629

What's Changed

• Fix edge case in 'findBindingAtPosition' when looking up global binding at start of file by @JohnnyMorganz in #1254
• implement leading bar and ampersand in types by @jackdotink in #1286
• Fix incorrect comment in lgc.h by @zeux in #1288
• tests: Adjust conformance tests to account for array invariant by @zeux in #1289
• Implemented parsing logic for attributes
• Added lua_setuserdatametatable and lua_getuserdatametatable C API methods for a faster userdata metatable fetch compared to luaL_getmetatable. Note that metatable reference has to still be pinned in memory!

New Solver

• Further improvement to the assignment inference logic
• Fix many bugs surrounding constraint dispatch order

Native Codegen

• Add IR lowering hooks for custom host userdata types
• Add IR to create new tagged userdata objects
• Remove outdated NativeState

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Internal Contributors

Co-authored-by: Aaron Weiss aaronweiss@roblox.com
Co-authored-by: Alexander McCord amccord@roblox.com
Co-authored-by: Andy Friesen afriesen@roblox.com
Co-authored-by: Aviral Goel agoel@roblox.com
Co-authored-by: Vighnesh Vijay vvijay@roblox.com
Co-authored-by: Vyacheslav Egorov vegorov@roblox.com

New Contributors

• @jackdotink made their first contribution in #1286

Full Changelog: 0.628...0.629

0.628

What's new?

• Remove a case of unsound table.move optimization
• Add Luau stack slot reservations that were missing in REPL (fixes #1273)

New Type Solver

• Assignments have been completely reworked to fix a case of cyclic constraint dependency
• When indexing, if the fresh type's upper bound already contains a compatible indexer, do not add another upper bound
• Distribute type arguments over all type families sans eq, keyof, rawkeyof, and other internal type families
• Fix a case where buffers component weren't read in two places (fixes #1267)
• Fix a case where things that constitutes a strong ref were slightly incorrect
• Fix a case where constraint dependencies weren't setup wrt for ... in statement

Native Codegen

• Fix an optimization that splits TValue store only when its value and its tag are compatible
• Implement a system to plug additional type information for custom host userdata types

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Internal Contributors

Co-authored-by: Aaron Weiss aaronweiss@roblox.com
Co-authored-by: Alexander McCord amccord@roblox.com
Co-authored-by: Andy Friesen afriesen@roblox.com
Co-authored-by: Vighnesh Vijay vvijay@roblox.com
Co-authored-by: Vyacheslav Egorov vegorov@roblox.com

0.627

What's new?

New Type Solver

• Improved error messages for type families to describe what's wrong in more detail, and ideally without using the term type family at all.
• Change boolean and string singletons in type checking to report errors to the user when they've gotten an impossible type (indicating a type error from their context).
• Split debugging flags for type family reduction (DebugLuauLogTypeFamilies) from general solver logging (DebugLuauLogSolver).
• Improve type simplification to support patterns like (number | string) | (string | number) becoming number | string.

Native Code Generation

• Use templated luaV_doarith to speedup vector operation fallbacks.
• Various small changes to better support arm64 on Windows.

Internal Contributors

Co-authored-by: Aaron Weiss aaronweiss@roblox.com
Co-authored-by: Andy Friesen afriesen@roblox.com
Co-authored-by: James McNellis jmcnellis@roblox.com
Co-authored-by: Vighnesh Vijay vvijay@roblox.com
Co-authored-by: Vyacheslav Egorov vegorov@roblox.com

0.626

What's changed?

New Type Solver

• Fixed crash in numeric binary operation type families
• Results of an indexing operation are now comparable to nil without a false positive error
• Fixed a crash when a type that failed normalization was accessed
• Iterating on a free value now implies that it is iterable

Full Changelog: 0.625...0.626

0.625

What's changed?

• Fix warning issued when Cmake version is too low (contributed by OSS community)

New Solver

• Fix an issue with inhabitance testing of tables with cyclic properties
• Preserve error suppression during type unification
• Overhaul type reference counting in the constraint solver
• Other miscellaneous constraint ordering fixes

Native Codegen

• Fix incorrect assertion check in loadBytecodeTypeInfo

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Internal Contributors

Co-authored-by: Aaron Weiss aaronweiss@roblox.com
Co-authored-by: Alexander McCord amccord@roblox.com
Co-authored-by: Andy Friesen afriesen@roblox.com
Co-authored-by: Vighnesh Vijay vvijay@roblox.com
Co-authored-by: Vyacheslav Egorov vegorov@roblox.com

0.624

What's Changed

• CodeGen: Fix a typo in X64 (dis)assembler by @zeux in #1238
• Optimize table.concat. This function is now 1.4x-2x faster. #1243
• Optimize table.maxn. This function is now 5-14x faster
• Add benchmarks for native compilation with type info enabled by @vegorov-rbx in #1244
• Reserve Luau stack space for error message.

New Solver

• Globals can be type-stated, but only if they are already in scope
• Fix a stack overflow that could occur when normalizing certain kinds of recursive unions of intersections (of unions of intersections...)
• Fix an assertion failure that would trigger when the __iter metamethod has a bad signature

Native Codegen

• Type propagation and temporary register type hints
• Direct vector property access should only happen for names of right length
• BytecodeAnalysis will only predict that some of the vector value fields are numbers

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Internal Contributors

Co-authored-by: Alexander McCord amccord@roblox.com
Co-authored-by: Andy Friesen afriesen@roblox.com
Co-authored-by: Aviral Goel agoel@roblox.com
Co-authored-by: Vyacheslav Egorov vegorov@roblox.com
Full Changelog: 0.623...0.624

0.623

What's changed?

New Type Solver

• Unification of two fresh types no longer binds them together.
• Replaced uses of raw emplace with emplaceType to catch cyclic bound types when they are created.
• SetIndexerConstraint is blocked until the indexer result type is not blocked.
• Fix a case where a blocked type got past the constraint solver.
• Searching for free types should no longer traverse into ClassTypes.
• Fix a corner case that could result in the non-testable type ~{}.
• Fix incorrect flagging when any was a parameter of some checked function in nonstrict type checker.
• IterableConstraint now consider tables without __iter to be iterables.

Native Code Generation

• Improve register type info lookup by program counter.
• Generate type information for locals and upvalues

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Internal Contributors

Co-authored-by: Aaron Weiss aaronweiss@roblox.com
Co-authored-by: Alexander McCord amccord@roblox.com
Co-authored-by: Andy Friesen afriesen@roblox.com
Co-authored-by: James McNellis jmcnellis@roblox.com
Co-authored-by: Vighnesh Vijay vvijay@roblox.com
Co-authored-by: Vyacheslav Egorov vegorov@roblox.com

0.622

What's changed?

• Improved the actual message for the type errors for cannot call non-function when attempting to call a union of functions/callable tables. The error now correctly explains the issue is an inability to determine the return type of the call in this situation.
• Resolve an issue where tables and metatables were not correctly being cloned during instantiation (fixes #1176).
• Refactor luaM_getnextgcopage to luaM_getnextpage (generally removing gco prefix where appropriate).
• Optimize table.move between tables for large ranges of elements.
• Reformat a bunch of code automatically using clang-format.

New Type Solver

• Clean up minimally-used or unused constraints in the constraint solver (InstantiationConstraint, SetOpConstraint, SingletonOrTopTypeConstraint).
• Add a builtin singleton type family to replace SingletonOrTopTypeConstraint when inferring refinements.
• Fixed a crash involving type path reasoning by recording when type family reduction has taken place in the path.
• Improved constraint ordering by blocking on unreduced types families that are not yet proven uninhabitable.
• Improved the handling of SetIndexerConstraints for both better inference quality and to resolve crashes.
• Fix a crash when normalizing cyclic unions of intersections.
• Fix a crash when normalizing an intersection with the negation of unknown.
• Fix a number of crashes caused by missing follow calls on TypeIds.
• Changed type family reduction to correctly use a semantic notion of uninhabited types, rather than checking for never types specifically.
• Refactor the union and intersect type families to be variadic.

Native Code Generation

• Improve translation for userdata key get/set and userdata/vector namecall.
• Provide [top level] and [anonymous] as function names to FunctionStats as appropriate when no function name is available.
• Disable unwind support on Android platforms since it is unsupported.

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Internal Contributors

Co-authored-by: Aaron Weiss aaronweiss@roblox.com
Co-authored-by: Alexander McCord amccord@roblox.com
Co-authored-by: Andy Friesen afriesen@roblox.com
Co-authored-by: Aviral Goel agoel@roblox.com
Co-authored-by: Vighnesh Vijay vvijay@roblox.com
Co-authored-by: Vyacheslav Egorov vegorov@roblox.com

0.621

What's changed?

• Support for new 'require by string' RFC with relative paths and aliases in now enabled in Luau REPL application

New Type Solver

• Fixed assertion failure on generic table keys ([expr] = value)
• Fixed an issue with type substitution traversing into the substituted parts during type instantiation
• Fixed crash in union simplification when that union contained uninhabited unions and other types inside
• Union types in binary type families like add<a | b, c> are expanded into add<a, c> | add<b, c> to handle
• Added handling for type family solving creating new type families
• Fixed a bug with normalization operation caching types with unsolved parts
• Tables with uninhabited properties are now simplified to never
• Fixed failures found by fuzzer

Native Code Generation

• Added support for shared code generation between multiple Luau VM instances
• Fixed issue in load-store propagation and new tagged LOAD_TVALUE instructions
• Fixed issues with partial register dead store elimination causing failures in GC assists

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Full Changelog: 0.620...0.621

0.620

What's Changed

New Type Solver

• Many more fixes to crashes, assertions, and hangs
• Annotated locals now countermand the inferred types of locals, meaning that for a type type MyType = number | string, local foo : MyType = 5 behaves the same as local foo = 5 :: MyType, where before, foo would be assigned the type of the value on the rhs.
• Type Normalization now respects resource limits.
• Subtyping between classes and cyclic tables now supported

Native Code Generation

• Work on the Native Code Generation(NCG) allocator continues

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Internal Contributors

Co-authored-by: Aaron Weiss aaronweiss@roblox.com
Co-authored-by: Alexander McCord amccord@roblox.com
Co-authored-by: Andy Friesen afriesen@roblox.com
Co-authored-by: James McNellis jmcnellis@roblox.com
Co-authored-by: Vighnesh Vijay vvijay@roblox.com
Co-authored-by: Vyacheslav Egorov vegorov@roblox.com