Hey folks, another week means another Luau release! This one features a
number of bug fixes in the New Type Solver including improvements to
user-defined type functions and a bunch of work to untangle some of the
outstanding issues we've been seeing with constraint solving not
completing in real world use. We're also continuing to make progress on
crashes and other problems that affect the stability of fragment
autocomplete, as we work towards delivering consistent, low-latency
autocomplete for any editor environment.
## New Type Solver
- Fix a bug in user-defined type functions where `print` would
incorrectly insert `\1` a number of times.
- Fix a bug where attempting to refine an optional generic with a type
test will cause a false positive type error (fixes#1666)
- Fix a bug where the `refine` type family would not skip over
`*no-refine*` discriminants (partial resolution for #1424)
- Fix a constraint solving bug where recursive function calls would
consistently produce cyclic constraints leading to incomplete or
inaccurate type inference.
- Implement `readparent` and `writeparent` for class types in
user-defined type functions, replacing the incorrectly included `parent`
method.
- Add initial groundwork (under a debug flag) for eager free type
generalization, moving us towards further improvements to constraint
solving incomplete errors.
## Fragment Autocomplete
- Ease up some assertions to improve stability of mixed-mode use of the
two type solvers (i.e. using Fragment Autocomplete on a type graph
originally produced by the old type solver)
- Resolve a bug with type compatibility checks causing internal compiler
errors in autocomplete.
## Lexer and Parser
- Improve the accuracy of the roundtrippable AST parsing mode by
correctly placing closing parentheses on type groupings.
- Add a getter for `offset` in the Lexer by @aduermael in #1688
- Add a second entry point to the parser to parse an expression,
`parseExpr`
## Internal Contributors
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: James McNellis <jmcnellis@roblox.com>
Co-authored-by: Talha Pathan <tpathan@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
---------
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Varun Saini <61795485+vrn-sn@users.noreply.github.com>
Co-authored-by: Alexander Youngblood <ayoungblood@roblox.com>
Co-authored-by: Menarul Alam <malam@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: Vighnesh <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
## What's Changed
General performance improvements and bug fixes. `lua_clonetable` was
added too.
### General
## Runtime
- Improvements were made to Luau's performance, including a
`lua_clonetable` function and optimizations to string caching. Buffer
read/write operations were optimized for big-endian machines.
## New Solver
- Crashes related to duplicate keys in table literals, fragment AC
crashes, and potential hash collisions in the StringCache.
- We now handle user-defined type functions as opaque and track interior
free table types.
## Require By String
- Require-by-string path resolution was simplified.
**Full Changelog**:
https://github.com/luau-lang/luau/compare/0.658...0.659
---
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Varun Saini <vsaini@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Yohoo Lin <yohoo@roblox.com>
---------
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Varun Saini <61795485+vrn-sn@users.noreply.github.com>
Co-authored-by: Alexander Youngblood <ayoungblood@roblox.com>
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# General
All code has been re-formatted by `clang-format`; this is not
mechanically enforced, so Luau may go out-of-sync over the course of the
year.
# New Solver
* Track free types interior to a block of code on `Scope`, which should
reduce the number of free types that remain un-generalized after type
checking is complete (e.g.: less errors like `'a <: number is
incompatible with number`).
# Autocomplete
* Fragment autocomplete now does *not* provide suggestions within
comments (matching non-fragment autocomplete behavior).
* Autocomplete now respects iteration and recursion limits (some hangs
will now early exit with a "unification too complex error," some crashes
will now become internal complier exceptions).
# Runtime
* Add a limit to how many Luau codegen slot nodes addresses can be in
use at the same time (fixes#1605, fixes#1558).
* Added constant folding for vector arithmetic (fixes#1553).
* Added support for `buffer.readbits` and `buffer.writebits` (see:
https://github.com/luau-lang/rfcs/pull/18).
---
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: David Cope <dcope@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
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This change implements math.lerp RFC with C function definition, builtin
function, builtin constant folding and tests.
The tests validate a few lerp properties by providing counter-examples
for popular lerp implementations; the testing is of course not
exhaustive, as exhaustive testing was done offline using fuzzing.
Type definitions will be updated separately.
Codegen support will be implemented separately: it requires new IR for
conditional
selects to represent the desired logic without using a branch.
benchmark / callgrind (map[branch:main name:luau-lang/benchmark-data], ubuntu-22.04) (push) Has been cancelled
build / macos (push) Has been cancelled
build / macos-arm (push) Has been cancelled
build / ubuntu (push) Has been cancelled
build / windows (Win32) (push) Has been cancelled
build / windows (x64) (push) Has been cancelled
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build / web (push) Has been cancelled
release / macos (push) Has been cancelled
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## New Solver
* Type functions should be able to signal whether or not irreducibility
is due to an error
* Do not generate extra expansion constraint for uninvoked user-defined
type functions
* Print in a user-defined type function reports as an error instead of
logging to stdout
* Many e-graphs bugfixes and performance improvements
* Many general bugfixes and improvements to the new solver as a whole
* Fixed issue with used-defined type functions not being able to call
each other
* Infer types of globals under new type solver
## Fragment Autocomplete
* Miscellaneous fixes to make interop with the old solver better
## Runtime
* Support disabling specific built-in functions from being fast-called
or constant-evaluated (Closes#1538)
* New compiler option `disabledBuiltins` accepts a list of library
function names like "tonumber" or "math.cos"
* Added constant folding for vector arithmetic
* Added constant propagation and type inference for vector globals
(Fixes#1511)
* New compiler option `librariesWithKnownMembers` accepts a list of
libraries for members of which a request for constant value and/or type
will be made
* `libraryMemberTypeCb` callback is called to get the type of a global,
return one of the `LuauBytecodeType` values. 'boolean', 'number',
'string' and 'vector' type are supported.
* `libraryMemberConstantCb` callback is called to setup the constant
value of a global. To set a value, C API `luau_set_compile_constant_*`
or C++ API `setCompileConstant*` functions should be used.
---
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: Daniel Angel <danielangel@roblox.com>
Co-authored-by: Jonathan Kelaty <jkelaty@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Varun Saini <vsaini@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
---------
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: David Cope <dcope@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Junseo Yoo <jyoo@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Varun Saini <61795485+vrn-sn@users.noreply.github.com>
Co-authored-by: Alexander Youngblood <ayoungblood@roblox.com>
Co-authored-by: Varun Saini <vsaini@roblox.com>
Co-authored-by: Andrew Miranti <amiranti@roblox.com>
Co-authored-by: Shiqi Ai <sai@roblox.com>
Co-authored-by: Yohoo Lin <yohoo@roblox.com>
Co-authored-by: Daniel Angel <danielangel@roblox.com>
Co-authored-by: Jonathan Kelaty <jkelaty@roblox.com>
* New `vector` library! See https://rfcs.luau.org/vector-library.html
for details
* Replace the use of non-portable `strnlen` with `memchr`. `strnlen` is
not part of any C or C++ standard.
* Introduce `lua_newuserdatataggedwithmetatable` for faster tagged
userdata creation of userdata with metatables registered with
`lua_setuserdatametatable`
Old Solver
* It used to be the case that a module's result type would
unconditionally be inferred to be `any` if it imported any module that
participates in any import cycle. This is now fixed.
New Solver
* Improve inference of `table.freeze`: We now infer read-only properties
on tables after they have been frozen.
* We now correctly flag cases where `string.format` is called with 0
arguments.
* Fix a bug in user-defined type functions where table properties could
be lost if the table had a metatable
* Reset the random number seed for each evaluation of a type function
* We now retry subtyping arguments if it failed due to hidden variadics.
---------
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Alexander McCord <amccord@roblox.com>
Co-authored-by: Vighnesh <vvijay@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: David Cope <dcope@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Junseo Yoo <jyoo@roblox.com>
# What's Changed?
- Code refactoring with a new clang-format
- More bug fixes / test case fixes in the new solver
## New Solver
- More precise telemetry collection of `any` types
- Simplification of two completely disjoint tables combines them into a
single table that inherits all properties / indexers
- Refining a `never & <anything>` does not produce type family types nor
constraints
- Silence "inference failed to complete" error when it is the only error
reported
---
### Internal Contributors
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Dibri Nsofor <dnsofor@roblox.com>
Co-authored-by: Jeremy Yoo <jyoo@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
---------
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 <vvijay@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: David Cope <dcope@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
# What's changed?
* Optimize table.maxn. This function is now 5-14x faster
* 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
---
## 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>
# Old Solver:
- Fix a bug in the old solver where a user could use the keyword
`typeof` as the name of a type alias.
- Fix stringification of scientific notation to omit a trailing decimal
place when not followed by a digit e.g. `1.e+20` -> `1e+20`
# New Solver
- Continuing work on the New non-strict mode
- Introduce `keyof` and `rawkeyof` type function for acquiring the type
of all keys in a table or class
(https://github.com/luau-lang/rfcs/pull/16)
---
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: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
---------
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: David Cope <dcope@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
## What's changed
- `bit32.byteswap` added
([RFC](4f543ec23b/docs/function-bit32-byteswap.md))
- Buffer library implementation
([RFC](4f543ec23b/docs/type-byte-buffer.md))
- Fixed a missing `stdint.h` include
- Fixed parser limiter for recursive type annotations being kind of
weird (fixes#645)
### Native Codegen
- Fixed a pair of issues when lowering `bit32.extract`
- Fixed a narrow edge case that could result in an infinite loop without
an interruption
- Fixed a negative array out-of-bounds access issue
- Temporarily reverted linear block predecessor value propagation
### New type solver
- We now type check assignments to annotated variables
- Fixed some test cases under local type inference
- Moved `isPending` checks for type families to improve performance
- Optimized our process for testing if a free type is sufficiently
solved
- Removed "none ptr" from lea instruction disassembly logging
### Build system & tooling
- CMake configuration now validates dependencies to maintain separation
between components
- Improvements to the fuzzer coverage
- Deduplicator for fuzzed callstacks
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
I've decided to take a stab at implementing `bit32.byteswap` from the
[recently merged
RFC](https://github.com/Roblox/luau/blob/master/rfcs/function-bit32-byteswap.md).
I asked on Discord for some guidance, but for the sake of posterity:
this is my first time doing this and I am likely to have made some
mistakes.
The biggest gaps in this implementation are the lack of tests and the
lack of native codegen support. I'd appreciate help with those since I'm
not sure what's relevant for me to touch for tests, and I'm told that
relevant assembler instructions don't exist publicly yet. Intuition
tells me that Luau-side tests would go into
`tests/conformance/bitwise.luau` but this is not well documented and I'm
not sure how I'm meant to test built-in implementations.
The current implementation compiles down to `bswap` and `rev` on x86 and
ARM respectively when optimized.
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
* 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)
* Improved parsing error messages
* Fixed crash on null pointer access in unification (fixes#1017)
* Native code support is enabled by default and `native=1`
(make)/`LUAU_NATIVE` (CMake)/`-DLUA_CUSTOM_EXECUTION` configuration is
no longer required
New typechecker:
* New subtyping check can now handle generic functions and tables
(including those that contain cycles)
Native code generation:
* 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
Type checker/autocomplete:
* `Luau::autocomplete` no longer performs typechecking internally, make
sure to run `Frontend::check` before performing autocomplete requests
* Autocomplete string suggestions without "" are now only suggested
inside the ""
* Autocomplete suggestions now include `function (anonymous autofilled)`
key with a full suggestion for the function expression (with arguments
included) stored in `AutocompleteEntry::insertText`
* `AutocompleteEntry::indexedWithSelf` is provided for function call
suggestions made with `:`
* Cyclic modules now see each other type exports as `any` to prevent
memory use-after-free (similar to module return type)
Runtime:
* Updated inline/loop unroll cost model to better handle assignments
(Fixes https://github.com/Roblox/luau/issues/978)
* `math.noise` speed was improved by ~30%
* `table.concat` speed was improved by ~5-7%
* `tonumber` and `tostring` now have fastcall paths that execute ~1.5x
and ~2.5x faster respectively (fixes#777)
* Fixed crash in `luaL_typename` when index refers to a non-existing
value
* Fixed potential out of memory scenario when using `string.sub` or
`string.char` in a loop
* Fixed behavior of some fastcall builtins when called without arguments
under -O2 to match original functions
* Support for native code execution in VM is now enabled by default
(note: native code still has to be generated explicitly)
* `Codegen::compile` now accepts `CodeGen_OnlyNativeModules` flag. When
set, only modules that have a `--!native` hot-comment at the top will be
compiled to native code
In our new typechecker:
* Generic type packs are no longer considered to be variadic during
unification
* Timeout and cancellation now works in new solver
* Fixed false positive errors around 'table' and 'function' type
refinements
* Table literals now use covariant unification rules. This is sound
since literal has no type specified and has no aliases
* Fixed issues with blocked types escaping the constraint solver
* Fixed more places where error messages that should've been suppressed
were still reported
* Fixed errors when iterating over a top table type
In our native code generation (jit):
* 'DebugLuauAbortingChecks' flag is now supported on A64
* LOP_NEWCLOSURE has been translated to IR
* Fixed gcc warning about uninitialized `std::optional`
* Fixed inlining of functions when they are used to compute their own
arguments
In the new type solver:
* Type families that are not part of a function signature cannot be
resolved at instantiation time and will now produce an error. This will
be relaxed in the future when we get constraint clauses on function
signatures (internally)
* `never` type is now comparable
* Improved typechecking of `for..in` statements
* Fixed checks for number type in `Add` type family
* Performance was improved, with particularly large gains on large
projects
And in native code generation (jit):
* We eliminated the call instruction overhead when native code support
is enabled in the VM
* Small optimizations to arm64 lowering
* Reworked LOP_GETIMPORT handling to reduce assembly code size
* Fixed non-deterministic binary output
* Fixed bad code generation caused by incorrect SSA to VM register links
invalidation
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
* Fixed incorrect lexeme generated for string parts in the middle of an
interpolated string (Fixes https://github.com/Roblox/luau/issues/744)
* DeprecatedApi lint can report some issues without type inference
information
* Fixed performance of autocomplete requests when suggestions have large
intersection types (Solves
https://github.com/Roblox/luau/discussions/847)
* Marked `table.getn`/`foreach`/`foreachi` as deprecated ([RFC:
Deprecate
table.getn/foreach/foreachi](https://github.com/Roblox/luau/blob/master/rfcs/deprecate-table-getn-foreach.md))
* With -O2 optimization level, we now optimize builtin calls based on
known argument/return count.
Note that this change can be observable if `getfenv/setfenv` is used to
substitute a builtin, especially if arity is different.
Fastcall heavy tests show a 1-2% improvement.
* Luau can now be built with clang-cl (Fixes
https://github.com/Roblox/luau/issues/736)
We also made many improvements to our experimental components.
For our new type solver:
* Overhauled data flow analysis system, fixed issues with 'repeat'
loops, global variables and type annotations
* Type refinements now work on generic table indexing with a string
literal
* Type refinements will properly track potentially 'nil' values (like
t[x] for a missing key) and their further refinements
* Internal top table type is now isomorphic to `{}` which fixes issues
when `typeof(v) == 'table'` type refinement is handled
* References to non-existent types in type annotations no longer resolve
to 'error' type like in old solver
* Improved handling of class unions in property access expressions
* Fixed default type packs
* Unsealed tables can now have metatables
* Restored expected types for function arguments
And for native code generation:
* Added min and max IR instructions mapping to vminsd/vmaxsd on x64
* We now speculatively extract direct execution fast-paths based on
expected types of expressions which provides better optimization
opportunities inside a single basic block
* Translated existing math fastcalls to IR form to improve tag guard
removal and constant propagation
* Support `["prop"]` syntax on class definitions in definition files.
(#704)
* Improve type checking performance for complex overloaded functions
* Fix rare cases of incorrect stack traces for out of memory errors at
runtime
- Type aliases can no longer override primitive types; attempts to do
that will result in a type error
- Fix misleading type error messages for mismatches in expression list
length during assignment
- Fix incorrect type name display in certain cases
- setmetatable/getmetatable are now ~2x faster
- tools/perfstat.py can be used to display statistics about profiles
captured via --profile switch
- Improve refinement support for unions, in particular it's now possible to implement tagged unions as a union of tables where individual branches use a string literal type for one of the fields.
- Fix `string.split` type information
- Optimize `select(_, ...)` to run in constant time (~2.7x faster on VariadicSelect benchmark)
- Improve debug line information for multi-line assignments
- Improve compilation of table literals when table keys are constant expressions/variables
- Use forward GC barrier for `setmetatable` which slightly accelerates GC progress
