0.507

Analysis changes

• Type ascription (::) now permits casts between related types in both directions, allowing to refine or loosen the type (RFC #56)
• Fix type definition for tonumber to return number? since the input string isn't guaranteed to contain a valid number
• Fix type refinements for field access via []
• Many stability fixes for type checker
• Provide extra information in error messages for type mismatches in more cases
• Improve performance of type checking for large unions when union members are string literals

Runtime changes

• Fix some C APIs like lua_equal or lua_getfield triggering GC assertions in presence of metatables
• Add lua_getcoverage API for code coverage collection
• Improve performance of truthiness checks in some cases, particularly on Apple M1, resulting in 10-25% perf gains on qsort benchmark depending on the CPU/compiler
• Fix support for little-endian systems; IBM s390x here we go!

CLI changes

• Add coverage reporting support to Repl (--coverage command line argument)
• Add shebang support by @Rerumu in #149
• Work around code signing issues during Makefile builds on macOS

Community contributions

• Fix Json Encoding for AstArray by @xgladius in #279
• Add Grammar documentation by @JohnnyMorganz in #266

0.506

Changes

• Fix some cases where type checking would overflow the native stack
• Improve autocomplete behavior when assigning a partially written function call (not currently exposed through command line tools)
• Improve autocomplete type inference feedback for some expressions where previously the type would not be known
• Improve quantification performance during type checking for large types
• Improve type checking for table literals when the expected type of the table is known because of a type annotation
• Fix type checking errors in cases where required module has errors in the resulting type
• Fix debug line information for multi-line chained call sequences (#255)
• lua_ref can no longer be used with LUA_REGISTRYINDEX to prevent mistakes when migrating Lua FFI (#247)
• Fix assertions and possible crashes when executing script code indirectly via metatable dispatch from lua_equal/lua_lessthan/lua_getfield/etc. (#259)
• Fix flamegraph scripts to run under Python 2

Community contributions

• Add luaL_checkboolean and luaL_optboolean by @MathematicalDessert in #221
• Expand vectors to 4 components using compile time switch by @petrihakkinen in #214
• Removed LUALIB_API from source file method bodies by @KaleidoDeer in #235
• Add LUA_GCCOUNTB option for lua_gc by @petrihakkinen in #254
• Fix luaL_sandbox leaving a value on the stack by @petrihakkinen in #253
• Allow reconfiguring VM defaults via build defines by @kunitoki in #260
• Fix luau_load 'env' to work with absolute stack index & add lua_absindex by @petrihakkinen in #263
• Add lua_isvector, luaL_checkvector and luaL_optvector by @petrihakkinen in #261

Breaking changes

This release introduces a small breaking change in lua.h (only relevant for embedders) to improve compatibility with Lua/LuaJIT:

• lua_newuserdata now takes 2 arguments; lua_newuserdatatagged should be used if the third argument was non-0.

0.505

Changes

• Improve error recovery during type checking
• Initial (not fully complete) implementation for singleton types (RFC #37)
• Implement a C-friendly interface for compiler (luacode.h)
• Remove C++ features from lua.h (removed default arguments from luau_load and lua_pushcfunction)
• Fix lua_breakpoint behavior when enabled=false
• Implement coroutine.close (RFC #88)

Community Contributions

• fix unable to find library -lpthread by @leleliu008 in #203

Breaking changes

This release introduces small breaking changes in lua.h (only relevant for embedders):

• luau_load env argument is now required, pass an extra 0
• lua_pushcfunction now must be called with 3 arguments; if you were calling it with 2 arguments, pass an extra NULL; if you were calling it with 4, use lua_pushcclosure.

These changes are necessary to make sure lua.h can be used from pure C - the future release will make it possible by adding an option to luaconf.h to change function name mangling to be C-compatible. We don't anticipate breaking the FFI interface in the future, but this change was necessary to restore C compatibility.

0.504

Changes

• Type mismatch errors now show detailed information for compound types, highlighting the mismatching component
• Fix string.pack bug on ARM when packing negative numbers using unsigned formats (#171)
• Implement bit32.countlz/countrz (RFC #89)
• Minor compiler throughput optimization (~2% faster compilation)
• Improve transpiler behavior for edge cases and better test coverage (not exposed through CLI at the moment)
• Improve error recovery when parsing invalid assignments
• Build fixes for fuzzing targets
• Add lua_getthreaddata/lua_setthreaddata to be able to associate custom data with coroutines

Community contributions

• Fold length operations when argument is a constant string by @bmcq-0 in #141
• Look for .luau before .lua in REPL & Analyze (#97) by @Kittenz in #124
• Fix CLI analysis reporting wrong file names by @Rerumu in #146
• Add userdata to lua_Callbacks by @LoganDark in #168
• Don't allow registry to be set to readonly by @LoganDark in #184
• Remove Roblox-specific mutable globals by @LoganDark in #185
• Save bytecode to file through CLI by @NotDSF in #170
• Feature: Web REPL using Emscripten by @MathematicalDessert in #138
• Fixes IFTODT error while compiling from an android device by @ThePotato97 in #199

0.503

Changes

• Support for time tracing for analysis/compiler (not currently exposed through CLI)
• Support for type pack arguments in type aliases (RFC: Type alias type packs #83)
• Basic support for require(path) in luau-analyze
• Add a lint warning for table.move with 0 index as part of TableOperation lint
• Remove last STL dependency from Luau.VM
• Minor VS2022 performance tuning
• Major optimizations to type checking performance on complex programs/types (up to two orders of magnitude speedup for programs
  involving huge tagged unions)
• Fix a few issues encountered by UBSAN
• Fix gcc-11 test builds
• Fix a rare corner case where luau_load wouldn't wake inactive threads which could result in a use-after-free due to GC

Community contributions

• Fix CLI abort when non lua string passed to error by @grant-h in #114
• Removes MismatchedCount argument swapping workaround by @cipharius in #103
• Spelling fixes by @jsoref in #119

0.501

First open-source release 🎉