0.598

What's Changed

• Include windows.h instead of Windows.h by @RadiantUwU in #1055
• Custom implementation of os.time for all platforms

Compiler

• Fix repeat..until loops with continue statement when until expression refers to constants #1042
• Fix repeat..until loops with continue statement when upvalues are used #1043
• Disable builtin constant folding at -O2 when getfenv/setfenv are used
• Bytecode version produced by the compiler has been upgraded to 4 (runtime support for v4 starts from 0.588).

New Type Checker

• Initial work toward type states.
• Rework most overloadable operators to use type families.
• Initial work toward our new nonstrict mode.

Native Codegen

• Fix native code generation for dead loops
• Annotate top-level functions as cold to avoid compiling them to native code
• Slightly smaller/faster X64 calls to Luau functions
• Slightly smaller/faster A64 calls for both Luau and C functions
• Inline constant array index offset into the load/store instruction
• Increase X64 spill slots from 5 to 13

New Contributors

• @RadiantUwU made their first contribution in #1055

Full Changelog: 0.597...0.598

0.597

New Type Solver

• Implement bidirectional type inference for higher order functions so that we can provide a more precise type improving the autocomplete's human factors.
• We seal all tables, so we changed the stringification to make it a little lighter on users.
• Fixed a case of array-out-of-bound access.
• Type families no longer depends on TxnLog and Unifier.
• Type refinements now waits until the free types are sufficiently solved.

Native Code Generation

• Remove cached slot lookup for executeSETTABLEKS function because it is a fallback in the event of a cache miss, making the cached slot lookup redundant.
• Optimized repeated array lookups, e.g. a[3] in a[3] = a[3] / 2 is done once.

Misc

• On some platforms, it is necessary to use gmtime_s with the arguments reversed to get the current time. You can now define DOCTEST_CONFIG_USE_GMTIME_S to build and run unit tests on those platforms.

Full Changelog: 0.596...0.597

0.596

What's Changed

• Support Control Flow type Refinements for "break" and "continue" statements by @AmberGraceSoftware in #1004
• The old type unification engine will now report a more fine-grained error at times, indicating that type normalization in particular failed

New Type Solver

• Refactor of Unifier2, the new unification implementation for Luau
• Completed MVP of new unification implementation
• Dramatically simplified overload selection logic
• Type family reduction can now apply sooner to free types that have been solved
• Subtyping now supports table indexers
• Generalization now replaces bad generics with unknown

Native Code Generation

• Reduce stack spills caused by FINDUPVAL and STORE_TAG
• Generate SHL/SHR/SAR/rotates with immediate operands in X64
• Removed redundant case re-check in table lookup fallback

New Contributors

• @AmberGraceSoftware made their first contribution in #1004

Full Changelog: 0.595...0.596

0.595

What's new

• Rerun clang-format on the code
• Fix the variance on indexer result subtyping. This fixes some issues with inconsistent error reporting.
• Fix a bug in the normalization logic for intersections of strings
• Demo site: case sensitive highlighting by @Someon1e in #1040

New Type Solver

• New overload selection logic
• Subtype tests now correctly treat a generic as its upper bound within that generic's scope
• Semantic subtyping for negation types
• Semantic subtyping between strings and compatible table types like {lower: (string) -> string}
• Further work toward finalizing our new subtype test
• Correctly generalize module-scope symbols

Native Codegen

• Lowering statistics for assembly
• Make executable allocation size/limit configurable without a rebuild. Use FInt::LuauCodeGenBlockSize and FInt::LuauCodeGenMaxTotalSize.

New Contributors

• @Someon1e made their first contribution in #1040

Full Changelog: 0.594...0.595

0.594

Analysis Changes

• Fixed generic variadic function unification succeeding when it should have reported an error

Other Changes

• Fixed Frontend::markDirty not working on modules that were not typechecked yet
• Fix build & test conformance issues on mingw32/gcc and mingw64/clang by @jdpatdiscord in #1023
• Update syntax.md by @zeux in #1035

New Type Solver

• Implemented semantic subtyping check for function types

Native Code Generation

• Improved performance of numerical loops with a constant step
• Simplified IR for bit32.extract calls extracting first/last bits
• Improved performance of NaN checks

0.593

Floor division operator //

Luau now supports floor division operator //; by default it works on numbers and is equivalent to math.floor(a / b), but it can also be overridden for other types using __idiv metamethod. The operator has the same syntax and semantics as // in Lua 5.3; see #832 for full RFC.

Analysis Changes

• Autocomplete now shows end within do blocks
• Restore BraceType when using Lexer::lookahead (fixes #1019)

New Type Solver

• Enhance subtyping tests to support metatables, string singletons, and class types

Native Codegen

• Fixed clobbering of non-volatile xmm registers on Windows
• Optimize redundant table slot lookups
• Improve value propagation optimizations to work across basic blocks in some cases
• Implemented IR translation of table.insert builtin
• Fixed mmap error handling on macOS/Linux

0.592

Analysis Changes

• Improved parsing error messages
• Fixed crash on null pointer access in unification (fixes #1017)

Other Changes

• AST queries at position where function name is will now return AstExprLocal
• Lexer performance has been slightly improved
• Fixed incorrect string singleton autocomplete suggestions (fixes #858)
• Native code support is enabled by default and native=1 (make)/LUAU_NATIVE (CMake)/-DLUA_CUSTOM_EXECUTION configuration is no longer required

New Type Solver

• New subtyping check can now handle generic functions and tables (including those that contain cycles)

Native Codegen

• Loops with non-numeric parameters are now handled by VM to streamline native code
• Array size check can be optimized away in SETLIST
• On failure, CodeGen::compile returns a reason
• Fixed clobbering of non-volatile xmm registers on Windows

0.591

What's Changed

• LinterConfig.h: add missing stdint.h include by @xgqt in #1010
• Fix a use-after-free bug in the new type cloning algorithm
• Tighten up the type of coroutine.wrap. It is now <A..., R...>(f: (A...) -> R...) -> ((A...) -> R...)
• Break .luaurc out into a separate library target Luau.Config. This makes it easier for applications to reason about config files without also depending on the type inference engine.
• Move typechecking limits into FrontendOptions. This allows embedders more finely-grained control over autocomplete's internal time limits.
• Fix a stability issue with debugger debugprotectederror callback allowing break in non-yieldable contexts

New Type Solver

• Initial work toward Local Type Inference
• Introduce a new subtyping test. This will be much nicer than the old test because it is completely separate both from actual type inference and from error reporting.

Native Code Generation

• Added function to compute iterated dominance frontier
• Optimize barriers in SET_UPVALUE when tag is known
• Cache lua_State::global in a register on A64
• Optimize constant stores in A64 lowering
• Track table array size state to optimize array size checks
• Add split tag/value store into a VM register
• Check that spills can outlive the block only in specific conditions

New Contributors

• @xgqt made their first contribution in #1010

Full Changelog: 0.590...0.591

0.590

Analysis Changes

• Better indentation in multi-line type mismatch error messages
• Error message clone can no longer cause a stack overflow (when typechecking with retainFullTypeGraphs set to false); fixes #975

Runtime Changes

• string.format with %s is now ~2x faster on strings smaller than 100 characters

Other Changes

• Use const char* const* over const char** by @LoganDark in #1005
• Add luau-compile to .gitignore by @j-hui in #995

Native Codegen

• All VM side exits will block return to the native execution of the current function to preserve correctness
• Fixed executable page allocation on Apple platforms when using hardened runtime
• Added statistics for code generation (no. of functions compiler, memory used for different areas)
• Fixed issue with function entry type checks performed more that once in some functions

New Contributors

• @j-hui made their first contribution in #995

Full Changelog: 0.589...0.590

0.589

Analysis Changes

• Progress toward a diffing algorithm for types. We hope that this will be useful for writing clearer error messages.
• Add a missing recursion limiter in Unifier::tryUnifyTables. This was causing a crash in certain situations.

Runtime Changes

• Luau heap graph enumeration improvements:
  • Weak references are not reported
  • Added tag as a fallback name of non-string table links
  • Included top Luau function information in thread name to understand where thread might be suspended
• Constant folding for math.pi and math.huge at -O2
• Optimize string.format and %*
  • This change makes string interpolation 1.5x-2x faster depending on the number and type of formatted components, assuming a few are using primitive types, and reduces associated GC pressure.

Other changes

• Add dark theme by @Someon1e in #991
• Fix some EBNF cases in grammar.md by @cassanof in #999

New type checker

• Initial work toward tracking the upper and lower bounds of types accurately.

Native code generation (JIT)

• Add IrCmd::CHECK_TRUTHY for improved assert fast-calls
• Do not compute type map for modules without types
• Capture metatable+readonly state for NEW_TABLE IR instructions
• Replace JUMP_CMP_ANY with CMP_ANY and existing JUMP_EQ_INT
• Add support for exits to VM with reentry lock in VmExit

New Contributors

• @cassanof made their first contribution in #999

Full Changelog: 0.588...0.589