0.542

Analysis changes

• Fix DeprecatedGlobal warning text in cases when the global is deprecated without a suggested alternative
• Fix an off-by-one error in type error text for incorrect use of string.format
• Reduce stack consumption further during parsing, hopefully eliminating stack overflows during parsing/compilation

Runtime changes

• Simplify garbage collection treatment of upvalues, reducing cache misses during sweeping stage and reducing the cost of upvalue assignment (SETUPVAL)
• Simplify garbage collection treatment of sleeping and alive threads, reducing cache misses during sweeping stage
• Simplify management of string buffers, removing redundant linked list operations

Community contributions

• Pass environment scope to autocomplete typechecker by @JohnnyMorganz in #610
• String interpolation by @Kampfkarren in #614

Note on interpolated strings

Support for interpolated strings is marked as experimental in this release as the syntax is being validated for compatibility with editors and future proposals; to use it in command-line tools, pass --fflags=LuauInterpolatedStringBaseSupport to enable it early.

0.541

Analysis changes

• Fix autocomplete not suggesting globals defined after the cursor (fixes #622)
• Improve type checker stability

Runtime changes

• Reduce parser C stack consumption which fixes some stack overflow crashes on deeply nested sources
• Improve performance of bit32.extract/replace when width is implied (~3% faster chess)
• Improve performance of bit32.extract when field/width are constants (~10% faster base64)
• Heap dump now annotates thread stacks with local variable/function names

Community contributions

• Fix lint.md formatting by @Mactavsin in #637
• Prevent overflow in lua_newuserdatadtor by @XmiliaH in #639

0.540

Analysis changes

• Add ComparisonPrecedence lint to warn about erroneous use of not with comparisons, e.g not a == b where a ~= b was intended
• Several stability and performance improvements in the type checker

Runtime changes

• Bytecode compiler now emits optimized instruction sequences for multiple assignments, accelerating some benchmarks by 10%
• Fix reachability analysis for weak keys/values in heapgraph.py
• Fix CodeGen test failures on big endian architectures

Community contributions

• Add autocomplete context to result by @JohnnyMorganz in #611

0.539

Analysis changes

• Introduce IntegerParsing lint that warns on uses of integer literals that exceed 2^64 (fixes #518)
• Fix minor inconsistencies in synthesized names for types with metatables

Runtime changes

• Comparisons with constants are now significantly faster when using clang as a compiler (10-50% gains on internal benchmarks)
• Luau compiler now emits bytecode with version 3; version 2 is still supported but will be removed in about a month
• When calling non-existent methods on tables or strings, foo:bar now produces a more precise error message (fixes #255)

Community contributions

• Add Ctrl-C handling to the REPL by @jaykru in #537
• Add %* format specifier by @Kampfkarren in #619

0.538

Analysis changes

• Improve autocomplete behavior in certain cases for : calls

Runtime changes

• Fix warnings on Xcode 14 beta due to use of sprintf
• Improve debug.traceback performance by 1.15-1.75x depending on the platform
• Fix a corner case with table assignment semantics when key didn't exist in the table and __newindex was defined: we now use Lua 5.2 semantics and call __newindex, which results in less wasted space, support for NaN keys in __newindex path and correct support for frozen tables (see #380, #565)

Community contributions

• Store AstExprFunction in astTypes for stats by @JohnnyMorganz in #612

0.537

Analysis changes

• Disable lower bounds calculation mode by default as we're fixing some underlying problems induced by it
• Disable precise computation of returned types in non-strict mode as it makes non-strict mode too strict
• Fix type checker stability with upcoming lower bounds calculation mode
• Fix type checking false positives with optionals & nested tables (fixes #596)
• Fix type checking false positives in non-strict mode when using generalized iteration

Runtime changes

• Optimize local reassignment (eg local foo = bar :: type) which is now free if neither local is mutated
• Minor cleanup in error messages for table operations

Community contributions

• Documentation of round tie-breaking by @memery-rbx in #602

0.536

Analysis changes

• Fix bugs in type normalization of self-recursive union types
• Fix interaction between never types and operator type inference
• Fix type widening for functions that return a union of singleton string types
• string.match/string.find now return a more precise type if the match pattern is a string literal
• Type checker now supports passing strings to functions that use a string-like API even if the argument types aren't annotated.

Runtime changes

• Add support for --!optimize to be able to control optimization level from source
• Compiler now replaces some calls to builtin functions with a constant if all arguments are known when using -O2
• Compiler now recognizes builtin calls for the purpose of cost modeling, which improves inlining/unrolling of functions with builtin calls
• lua_breakpoint can now place the breakpoint after the requested line at the earliest executable location; it returns the line where the breakpoint was placed, or -1 on error.
• lua_Callbacks::useratom is now called lazily when the atom is requested via lua_tostringatom/lua_namecallatom, instead of eagerly during string construction.

Community contributions

• Improve description of bit32.extract. by @Anaminus in #585
• Add lua_setuserdatatag to update userdata tags by @khvzak in #588

0.535

Analysis changes

• Implement support for unknown / never types (RFC #434)
• Improve type inference for higher order generic functions
• Improve type checking for combinations of intersections and generics
• Fix a bug where type arena ownership invariant could be violated, causing stability issues
• Fix a bug where internal type error could be presented to the user
• string.gmatch now infers returned types based on the pattern when using a literal

Runtime changes

• Fix a bug with negative zero in vector components when using vectors as table keys
• Slightly reduce interpreter I$ footprint

Community contributions

• Fix op used when stringifying AstExprIndexName by @JohnnyMorganz in #572
• Store resolved types in astResolvedTypes by @JohnnyMorganz in #574
• Use syntheticName for stringified MetatableTypeVar by @JohnnyMorganz in #563

0.534

Analysis changes

• Fix a bug in parser that erroneously permitted type packs with named elements in generic types, e.g. Foo<(a: number, b: number)> isn't valid syntax
• Fix a bug in parser that erroneously truncated hexadecimal or binary literals that are longer than 64-bit; these literals are now rejected (#518)

Runtime changes

• Implement support for __len metamethod for tables, and a rawlen builtin function (RFC #536)
• Improve performance of iteration through tables

Community contributions

• Fix broken link in typecheck.md by @natteko in #568

0.533

Analysis changes

• Fix cases when an internal module name is used in type errors instead of a human-readable equivalent

Runtime changes

• Add LUAU_EXTERN_C CMake option to simplify uses of Luau via C API from other languages

Community contributions

• Correct string.find and string.match return types by @Qualadore in #554