## What's Changed?
This week we have an update with an implementation for one of the RFCs
we had approved before, an improvement of the new type solver and a
small Lua 5.1 C API compatibility improvement.
* `@deprecated` attribute can now have a custom suggestion for a
replacement and a reason message as described in [deprecated attribute
parameters
RFC](https://rfcs.luau.org/syntax-attribute-functions-deprecated.html)
For example:
```luau
@[deprecated {reason = "foo suffers from performance issues", use = "bar"}]
local function foo()
...
end
-- Function 'foo' is deprecated, use 'bar' instead. foo suffers from performance issues
foo()
```
* `lua_cpcall` C API function has been restored both for compatibility
with Lua 5.1 and as a safe way to enter protected call environment to
work with Luau C API functions that may error
Instead of
```
if (!lua_checkstack(L, 2))
return -1;
lua_pushcfunction(L, test, nullptr);
lua_pushlightuserdata(L, context);
int status = lua_pcall(L, 1, 0, 0);
```
you can simply do
```
int status = lua_cpcall(L, test, context);
```
* In Luau CLI, required module return values can now have any type
## New Type Solver
- Additional improvements on type refinements used with external types
should fix some reported false positive errors where types refined to
`never`
- Fixed an issue in recursive refinement types in a form of `t1 where t1
= refine<t1, _>` getting 'stuck'
- Fixed an issue in subtyping of generic functions, it is now possible
to assign `<T>(T, (T) -> T) -> T` to `(number, <X>(X) -> X) -> number`
- Fixed an ICE caused by recursive types (Fixes#1686)
- Added additional iteration and recursion limits to stop the type
solver before system resources are used up
## Internal Contributors
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Annie Tang <annietang@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Ilya Rezvov <irezvov@roblox.com>
Co-authored-by: Sora Kanosue <skanosue@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
## General
This week has been spent mostly on fixing bugs in incremental
autocomplete as well as making the new Type Solver more stable.
- Fixes a bug where registered "require" aliases were case-sensitive
instead of case-insensitive.
### New Type Solver
- Adjust literal sub typing logic to account for unreduced type
functions
- Implement a number of subtyping stack utilization improvements
- Emit a single error if an internal type escapes a module's interface
- Checked function errors in the New Non Strict warn about incorrect
argument use with one-indexed positions, e.g. `argument #1 was used
incorrectly` instead of `argument #0 was used incorrectly`.
- Improvements to type function reduction that let us progress further
while reducing
- Augment the generalization system to not emit duplicate constraints.
- Fix a bug where we didn't seal tables in modules that failed to
complete typechecking.
### Fragment Autocomplete
- Provide richer autocomplete suggestions inside of for loops
- Provide richer autocomplete suggestions inside of interpolated string
expressions
- Improve the quality of error messages when typing out interpolated
strings.
### Compiler
- Fixes REX encoding of extended byte registers for the x86 assembly
code generation.
- Fixes for table shape constant data encoding
---
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Sora Kanosue <skanosue@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>
## General
- Support AstStatDeclareGlobal output as a source string (via
@karl-police in #1889)
- Luau heap dump correctly reports the size of a string, now including
overhead for the string type
- Prevent yields from Luau `xpcall` error handling function.
## Analysis
- Avoid exponential blowup when normalizing union of normalized free
variables.
- Fix type pack-related bugs that caused infinite recursion when:
- A generic type pack was bound to itself during subtyping.
- In type pack flattening, when that same generic type pack was now
being bound another generic type pack which contained it.
- Properly simplify `any & (*error-type* | string)` to `*error-type* |
*error-type* | string` instead of hanging due to creating a huge union
type.
---
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Sora Kanosue <skanosue@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: 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>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Another week, another release!
## Analysis
- Hide errors in all solver modes (not just strict mode) if the only
error is that type inference failed to complete.
- Make various analysis components solver-agnostic (`setType`, `visit`,
`Scope` methods).
- Fix an issue where type inference may fail to complete when assigning
a table's member to the table itself.
- Fix a bug when accessing a table member on a local after the local is
assigned to in an if-else block, loop, or other similar language
construct.
- Fixes#1914.
- Fix type-checking of if-then-else expressions.
- Fixes#1815.
---
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
# What's Changed?
We've been hard at work fixing bugs and introducing new features!
## VM
* Include constant-folding information in Luau cost model for inlining
and loop unrolling
* ~1% improvement in compile times
## New Type Solver
* `Luau::shallowClone`'s last argument, whether to clone persistent
(builtin) types, is now non-optional.
* Refinements on properties of tables are now computed with a `read`
table property. This resolves some issues around refining table
properies and then trying to set them. Fixes#1344. Fixes#1651.
```
if foo.bar then
-- Prior to this release, this would be `typeof(foo) & { bar: ~(false?) }
-- Now, this is `typeof(foo) & { read bar: ~(false?) }
end
```
* The type function `keyof` should respect the empty string as a
property, as in:
```
-- equivalent to type Foo =""
type Foo = keyof<{ [""]: number }>
```
* Descend into literals to report subtyping errors for function calls:
this both improves bidirectional inference and makes errors more
specific. Before, the error reporting for a table with incorrect members
passed to a function would cite the entire table, but now it only cites
the members that are incorrectly typed.
* Fixes a case where intersecting two tables without any common
properties would create `never`, instead of a table with both of their
properties.
# Internal Contributors
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: James McNellis <jmcnellis@roblox.com>
Co-authored-by: Sora Kanosue <skanosue@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: Aviral Goel <agoel@roblox.com>
Co-authored-by: Vighnesh <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
# What's Changed?
This week comes with many improvements to the new type solver and an important fix to the garbage collection to make it more robust in memory constrained scenarios.
# Runtime
- Garbage collection will no longer run out of memory itself, which could have happened when resizing arrays to a smaller size
# New Type Solver
- Type refinements on external types should now work and should no longer normalize the type into `never`
- Improved error reporting when `string.format` is used with a dynamic format string
- Updated type signature of `getmetatable` library function to use the corresponding type function and produce better type inference
- Restored a type mismatch error when converting function types with different number of generic parameters, like `() -> ()` into `<T>() -> ()`
- Types resulting from compound assignments have been simplified, reducing cyclic type introduction and inference failures
- Fixed function generic types leaking into tables during bidirectional type inference (Fixes#1808 and #1821 )
- Stability and performance improvements (Fixes#1860 )
# Internal Contributors
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Sora Kanosue <skanosue@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>
## General
- Introduce `Frontend::parseModules` for parsing a group of modules at
once.
- Support chained function types in the CST.
## New Type Solver
- Enable write-only table properties (described in [this
RFC](https://rfcs.luau.org/property-writeonly.html)).
- Disable singleton inference for large tables to improve performance.
- Fix a bug that occurs when we try to expand a type alias to itself.
- Catch cancelation during the type-checking phase in addition to during
constraint solving.
- Fix stringification of the empty type pack: `()`.
- Improve errors for calls being rejected on the primitive `function`
type.
- Rework generalization: We now generalize types as soon as the last
constraint relating to them is finished. We think this will reduce the
number of cases where type inference fails to complete and reduce the
number of instances where `*blocked*` types appear in the inference
result.
## VM/Runtime
- Dynamically disable native execution for functions that incur a
slowdown (relative to bytecode execution).
- Improve names for `thread`/`closure`/`proto` in the Luau heap dump.
---
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: Talha Pathan <tpathan@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: Hunter Goldstein <hgoldstein@roblox.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>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
# General
* Expose an optional `get_alias` API as an alternative to `get_config`
in Luau.Require and Luau.RequireNavigator.
* Improve the Luau CLI's virtual filesystem implementation to fix bugs
related to `init.luau`. Fixes
https://github.com/luau-lang/luau/issues/1816
# New Type Solver
* Avoid double reporting errors when erroneous arguments are provided to
type functions.
* Fix some instances of unresovable cyclic type functions in loops by
only considering the first loop cycles. This results in some type
inference inaccuracies when the type of a variable in loop through
multiple iterations. Fixes
https://github.com/luau-lang/luau/issues/1413.
* Better generalize free types that have meaningful lower and upper
bounds, especially for table indexers.
* Report more specific errors when assigning or returning table literal
types, instead of citing the *entire* table type.
* Inference for functions with generic type packs is greatly improved.
* Fix some internal compiler exceptions when using type-stating
functions like `table.freeze` in `if _ then _ else _` expressions and
short circuiting binary operations.
* More consistently simplify unions of primitive types, especially in
array-like and dictionary-like tables.
* Fix a crash when type checking an erroneous type alias containing
`typeof` with a type assertion expression, as in:
```
type MyTable = {}
-- This will error at type checking time as it's a duplicate
type MyTable = typeof(setmetatable(SomeTable :: {}, SomeMetaTable));
```
* Fix a crash when inferring the type of an index expression where the
indexee is invalid (e.g. `nil`).
# Runtime
* Avoid throwing an exception from `luau_load` if we run out of memory.
* Type functions are no longer compiled and included in bytecode. Fixes
#1817.
* Fix some instances of Luau C API functions reading invalid debug
information (generally when the first or last instruction of a block was
being inspected). Fixes#1369.
* Avoid potential signed integer overflow when doing bounds checks on
tables.
* Support 16 byte aligned userdata objects when system allocation
alignment is also 16 bytes.
* Fix memory leaks in `Luau.Require` when using VM build with no
exceptions. Fixes#1827.
---------
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: James McNellis <jmcnellis@roblox.com>
Co-authored-by: Sora Kanosue <skanosue@roblox.com>
Co-authored-by: Talha Pathan <tpathan@roblox.com>
Co-authored-by: Varun Saini <vsaini@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
# General Changes
* Remove a `static_assert` that prevented Luau from building on 32-bit
targets.
* Fix `proxyrequire` (see https://github.com/luau-lang/luau/pull/1804)
* Replace contents API with new `loadname` API in Luau.Require
* Store the positions of `:` symbols in the CST.
* Fix a minor bug in the new incremental autocomplete engine: Properly
suggest `else` and `elseif` if the cursor is currently within an `if`
block.
# New Type Solver
* Allow generics to be substituted for negation types when performing
subtype tests
* Crash fixes
* Surface subtyping errors more consistently.
* Avoid creating double-negation types (like `~~(false?)`) when
generating constraints.
# 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: Sora Kanosue <skanosue@roblox.com>
Co-authored-by: Talha Pathan <tpathan@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: 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>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
# General
* Internally rename `ClassType` to `ExternType`. In definition files,
the syntax to define these types has changed to `declare extern type Foo
with prop: type end`
* Add `luarequire_registermodule` to Luau.Require
* Support yieldable Luau C functions calling other functions
* Store return types as `AstTypePack*` on Ast nodes
## New Solver
* Improve the logic that determines constraint dispatch ordering
* Fix a crash in the type solver that arose when using multi-return
functions with `string.format`
* Fix https://github.com/luau-lang/luau/issues/1736
* Initial steps toward rethinking function generalization:
* Instead of generalizing every type in a function all at once, we will
instead generalize individual type variables once their bounds have been
fully resolved. This will make it possible to properly interleave type
function reduction and generalization.
* Magic functions are no longer considered magical in cases where they
are not explicitly called by the code.
* The most prominent example of this is in `for..in` loops where the
function call is part of the desugaring process.
* Almost all magic functions work by directly inspecting the AST, so
they can't work without an AST fragment anyway.
* Further, none of the magic functions we have are usefully used in this
way.
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Sora Kanosue <skanosue@roblox.com>
Co-authored-by: Talha Pathan <tpathan@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>
# General
This week has been focused primarily on bugfixes, with a ton of
usability improvements to the new solver, fragment autocomplete, and the
concrete syntax tree project.
## Runtime
- Fix an assertion caused by failing to allocate native code pages.
- Expose a `lua_pushrequire` function, which performs the same
initialization steps as `luaopen_require` but does not register require
globally. This lets users create specialized, custom `requires`.
# New Solver
- Fix a bug in simplification of types caused by combinatorial explosion
of intersection and union types.
- Fix a memory leak in fragment autocomplete
- Improve the isolation of modules in fragment autocomplete
- Throw errors when users define a type function with the name `typeof`
- Continue to narrow intersection types which might be `never`.
- Major rework of generalization continues - we are blazing a new path
with eager + non-reentrant generalization and actively working to make
these more performant and less error prone.
- Improve the ability of `and/or` type functions to reduce, even when
their arguments are generic.
- Report arity mismatches for undersaturated calls with unknown
parameters
# New Non-Strict
- Extends the new non-strict mode to report unknown symbols in types
# Old Solver
- Fix a crash caused by excessive stack usage during typechecking
# Misc
- Improvements to Concrete Syntax Tree location tracking for string
table props.
---
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: Sora Kanosue <skanosue@roblox.com>
Co-authored-by: Talha Pathan <tpathan@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>
We have lots of new changes for you!
# What's Changed
## General
- We updated Luau's license year to 2025!
- We fixed a bug where large amounts of errors were being printed when
deep intersections of unions error.
## Require-by-String
This release introduces the `Luau.Require` library, which exposes the
runtime semantics of require-by-string, including support for the new
`@self` alias described in [this
RFC](https://github.com/luau-lang/rfcs/pull/109).
The library operates on a virtualized filesystem, allowing consumers to
specify navigation rules without assuming a filesystem context.
Documentation in `Require.h` explains how to enable the library, and the
`setupState` function in Repl.cpp demonstrates how we've integrated it
into the luau CLI tool. Note that the interface in `Require.h` is
written in C, which enables any application written in a language with a
C foreign-function interface to link against this library and enable
require-by-string. This makes it straightforward for any application
embedding Luau to support require-by-string, provided that it defines or
operates within an environment resembling a virtual filesystem.
The core navigation semantics of require-by-string have additionally
been pulled into the `Luau.RequireNavigator` library. While
`Luau.Require` internally depends on `Luau.RequireNavigator`, the latter
does not depend on the Luau VM. This library provides an interface for
inspecting require-by-string's navigation behavior and therefore serves
as a useful dependency for static tooling. Documentation for
`Luau.RequireNavigator` is available in `RequireNavigator.h`.
## Autocomplete
- We fixed a memory leak in fragment autocomplete!
## New Solver And Old Solver
- We've found a infinite iteration error over a type pack. We added a
way to detect this error and throw an `InternalCompileError` instead.
- We fix `table.freeze` not accounting for the first argument not
getting type stated. We fall back to regular inference instead.
- We fix a crash in the old solver with `length_error`.
- We fix a crash in the new solver stemming from generalization
reentrancy. Now we correctly generalize interior free types that do not
appear in a function signature.
- We fix a nil refinement. (Fixes
https://github.com/luau-lang/luau/issues/1687 and
https://github.com/luau-lang/luau/issues/1451)
### Internal Contributors
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Talha Pathan <tpathan@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>
Full Changelog: https://github.com/luau-lang/luau/compare/0.668...0.669
---------
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: Aviral Goel <agoel@roblox.com>
Co-authored-by: Vighnesh <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Hello all! Another week, another Luau release!
# Change to `lua_setuserdatametatable`
This release fixes#1710: `lua_setuserdatametatable` is being changed so
that it _only_ operates on the top of the stack: the `idx` parameter is
being removed. Prior to this, `lua_setuserdatametable` would set the
metatable of the value in the stack at `idx`, but _always_ pop the top
of the stack. The old behavior is available in this release as
`lua_setuserdatametatable_DEPRECATED`.
# General
This release exposes a generalized implementation of require-by-string's
autocomplete logic. `FileResolver` can now be optionally constructed
with a `RequireSuggester`, which provides an interface for converting a
given module to a `RequireNode`. Consumers of this new API implement a
`RequireNode` to define how modules are represented in their embedded
context, and the new API manages the logic specific to
require-by-string, including providing suggestions for require aliases.
This enhancement moves toward integrating require-by-string's semantics
into the language itself, rather than merely providing a specification
for community members to implement themselves.
# New Type Solver
* Fixed a source of potential `Luau::follow detected a Type cycle`
internal compiler exceptions when assigning a global to itself.
* Fixed an issue whereby `*no-refine*` (a type which should not be
visible at the end of type checking) was not being properly elided,
causing inference of class-like tables to become unreadable / induce
crashes in autocomplete.
* Fixed a case of incomplete constraint solving when performing basic
math in a loop
# Fragment Autocomplete
* Fixed several crashes related to not properly filling in scope
information for the fragments
* Fixed a source of memory corruption by isolating the return type of a
fragment when it is type checked.
* Improved performance by opting not to clone persistent types for the
fragment (e.g.: built in types)
# Internal Contributors
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Talha Pathan <tpathan@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: 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>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
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>
# General
- Additional logging enabled for fragment autocomplete.
## Roundtrippable AST
- Add a new `AstNode`, `AstGenericType`
- Retain source information for `AstExprTypeAssertion`
## New Type Solver
- New non-strict mode will report unknown symbol errors, e.g
```
foo = 5
local wrong1 = foob <- issue warning
```
- Fixed a bug where new non-strict mode failed to visit large parts of
the program.
- We now infer the types of unnanotated local variables in statements
with multiple assignments, e.g. `local x: "a", y, z = "a", f()`
- Fixed bugs in constraint dispatch ordering.
- Fixed a bug that caused an infinite loop between `Subtyping`,
`OverloadResolution`, and `Type Function Reduction`, by preventing calls
to `Type Function Reduction` being re-entrant.
- Fixed a crash in bidirectional type inference caused by asserting read
and write properties on a type that was readonly.
## Runtime
- Fix a stack overflow caused by `luaL_checkstack` consuming stack space
even if the function fails to reserve memory.
- Using '%c' with a 0 value in Luau string.format will append a '\0'.
Resolves https://github.com/luau-lang/luau/issues/1650
## Miscellaneous
- Miscellaneous small bugfixes for the new solver.
**Full Changelog**:
https://github.com/luau-lang/luau/compare/0.660...0.661
----
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Talha Pathan <tpathan@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: 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>
## 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>
benchmark / callgrind (map[branch:main name:luau-lang/benchmark-data], ubuntu-22.04) (push) Has been cancelled
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build / web (push) Has been cancelled
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## General
- Fix a parsing bug related to the starting position of function names.
- Rename Luau's `Table` struct to `LuaTable`.
## New Solver
- Add support for generics in user-defined type functions
([RFC](https://rfcs.luau.org/support-for-generic-function-types-in-user-defined-type-functions.html)).
- Provide a definition of `math.lerp` to the typechecker.
- Implement error suppression in `string.format`.
- Fixes#1587.
- Ensure function call discriminant types are always filled when
resolving `FunctionCallConstraint`.
---
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@roblox.com>
Co-authored-by: Talha Pathan <tpathan@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
benchmark / callgrind (map[branch:main name:luau-lang/benchmark-data], ubuntu-22.04) (push) Waiting to run
build / macos (push) Waiting to run
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build / ubuntu (push) Waiting to run
build / windows (Win32) (push) Waiting to run
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release / macos (push) Waiting to run
release / ubuntu (push) Waiting to run
release / windows (push) Waiting to run
release / web (push) Waiting to run
Implement RFC: 2-component vector constructor. This includes 2-component
overload for `vector.create` and associated fastcall function, and its
type definition. These features are controlled by a new feature flag
`LuauVector2Constructor`. Additionally constant folding now supports two
components when `LuauVector2Constants` feature flag is set.
Note: this work does not include changes to CodeGen. Thus calls to
`vector.create` with only two arguments are not natively compiled
currently. This is left for future work.
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
build / coverage (push) Has been cancelled
build / web (push) Has been cancelled
release / macos (push) Has been cancelled
release / ubuntu (push) Has been cancelled
release / windows (push) Has been cancelled
release / web (push) Has been cancelled
# 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>
benchmark / callgrind (map[branch:main name:luau-lang/benchmark-data], ubuntu-22.04) (push) Waiting to run
build / macos (push) Waiting to run
build / macos-arm (push) Waiting to run
build / ubuntu (push) Waiting to run
build / windows (Win32) (push) Waiting to run
build / windows (x64) (push) Waiting to run
build / coverage (push) Waiting to run
build / web (push) Waiting to run
release / macos (push) Waiting to run
release / ubuntu (push) Waiting to run
release / windows (push) Waiting to run
release / web (push) Waiting to run
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.
## What's Changed?
* Optimized the vector dot product by up to 24%
* Allow for x/y/z/X/Y/Z vector field access by registering a `vector`
metatable
with an `__index` method (Fixes#1521)
* Fixed a bug preventing consistent recovery from parse errors in table
types.
* Optimized `k*n` and `k+n` when types are known
* Allow fragment autocomplete to handle cases like the automatic
insertion of
parens, keywords, strings, etc., while maintaining a correct relative
positioning
### New Solver
* Allow for `nil` assignment to tables and classes with indexers
---------
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: 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>
* 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 new
* Added `math.map` function to the standard library, based on
https://rfcs.luau-lang.org/function-math-map.html
* `FileResolver` can provide an implementation of
`getRequireSuggestions` to provide auto-complete suggestions for
require-by-string
## New Solver
* In user-defined type functions, `readproperty` and `writeproperty`
will return `nil` instead of erroring if property is not found
* Fixed incorrect scope of variadic arguments in the data-flow graph
* Fixed multiple assertion failures
---
Internal Contributors:
Co-authored-by: Aaron Weiss <aaronweiss@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>
In this update, we continue to improve the overall stability of the new
type solver. We're also shipping some early bits of two new features,
one of the language and one of the analysis API: user-defined type
functions and an incremental typechecking API.
If you use the new solver and want to use all new fixes included in this
release, you have to reference an additional Luau flag:
```c++
LUAU_DYNAMIC_FASTINT(LuauTypeSolverRelease)
```
And set its value to `645`:
```c++
DFInt::LuauTypeSolverRelease.value = 645; // Or a higher value for future updates
```
## New Solver
* Fix a crash where scopes are incorrectly accessed cross-module after
they've been deallocated by appropriately zeroing out associated scope
pointers for free types, generic types, table types, etc.
* Fix a crash where we were incorrectly caching results for bound types
in generalization.
* Eliminated some unnecessary intermediate allocations in the constraint
solver and type function infrastructure.
* Built some initial groundwork for an incremental typecheck API for use
by language servers.
* Built an initial technical preview for [user-defined type
functions](https://rfcs.luau-lang.org/user-defined-type-functions.html),
more work still to come (including calling type functions from other
type functions), but adventurous folks wanting to experiment with it can
try it out by enabling `FFlag::LuauUserDefinedTypeFunctionsSyntax` and
`FFlag::LuauUserDefinedTypeFunction` in their local environment. Special
thanks to @joonyoo181 who built up all the initial infrastructure for
this during his internship!
## Miscellaneous changes
* Fix a compilation error on Ubuntu (fixes#1437)
---
Internal Contributors:
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Hunter Goldstein <hgoldstein@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: 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>
Co-authored-by: Junseo Yoo <jyoo@roblox.com>
### What's new
* Fixed many of the false positive errors in indexing of table unions
and table intersections
* It is now possible to run custom checks over Luau AST during
typechecking by setting `customModuleCheck` in `FrontendOptions`
* Fixed codegen issue on arm, where number->vector cast could corrupt
that number value for the next time it's read
### New Solver
* `error` type now behaves as the bottom type during subtyping checks
* Fixed the scope that is used in subtyping with generic types
* Fixed `astOriginalCallTypes` table often used by LSP to match the old
solver
---
### Internal Contributors
Co-authored-by: Aaron Weiss <aaronweiss@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>
# 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?
- Telemetry support for usage of any type in old/new solver
- Bug fixes and flag removals with the new solver
## New Solver
- Fixed constraint ordering bug to infer types more accurately
- Improved inferring a call to `setmetatable()`
## VM
- Restored global metatable lookup for `typeof` on lightuserdata to fix
unintentional API change (Fixes#1335)
---
### 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: 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?
- Fix#1137 by appropriately retaining additional metadata from
definition files throughout the type system.
- Improve Frontend for LSPs by appropriately allowing the cancellation
of typechecking while running its destructor.
## New Solver
- Added support for the `rawget` type function.
- Reduced overall static memory usage of builtin type functions.
- Fixed a crash where visitors could mutate a union or intersection type
and fail to invalidate iteration over them in doing so.
- Revised autocomplete functionality to not rely on a separate run of
the type solver when using the new solver.
- Implemented a more relaxed semantic rule for casting.
- Fixed some smaller crashes in the new solver.
## Native Code Generation
- Add additional codegen specialization for `math.sign`
- Cleaned up a large number of outstanding fflags in the code.
### 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: Jeremy Yoo <jyoo@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@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 new
* A bug in exception handling in GCC(11/12/13) on MacOS prevents our
test suite from running.
* Parser now supports leading `|` or `&` when declaring `Union` and
`Intersection` types (#1286)
* We now support parsing of attributes on functions as described in the
[rfc](https://github.com/luau-lang/rfcs/pull/30)
* With this change, expressions such as `local x = @native function(x)
return x+1 end` and `f(@native function(x) return x+1 end)` are now
valid.
* Added support for `@native` attribute - we can now force native
compilation of individual functions if the `@native` attribute is
specified before the `function` keyword (works for lambdas too).
### New Solver
* Many fixes in the new solver for crashes and instability
* Refinements now use simplification and not normalization in a specific
case of two tables
* Assume that compound assignments do not change the type of the
left-side operand
* Fix error that prevented Class Methods from being overloaded
### VM
* Updated description of Garbage Collector invariant
---
### 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>
---------
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 new
* 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
---
### 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>
### 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
---
### 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>
---------
Co-authored-by: Aaron Weiss <aaronweiss@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?
### 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 `ClassType`s.
- 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
---
### 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>
---------
Co-authored-by: Aaron Weiss <aaronweiss@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?
* 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 `TypeId`s.
* 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.
*
---
### 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>
---------
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?
* 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
---
### 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>
# 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
---
# 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>
---------
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
## New Type Solver
- Many fixes to crashes, assertions, and hangs
- Binary type family aliases now have a default parameter
- Added a debug check for unsolved types escaping the constraint solver
- Overloaded functions are no longer inferred
- Unification creates additional subtyping constraints for blocked types
- Attempt to guess the result type for type families that are too large
to resolve timely
## Native Code Generation
- Fixed `IrCmd::CHECK_TRUTHY` lowering in a specific case
- Detailed compilation errors are now supported
- More work on the new allocator
---
# 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: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
# What's changed
### Debugger
* Values after a 'continue' statement should not be accessible by
debugger in the 'until' condition
### New Type Solver
* Many fixes to crashes and hangs
* Better bidirectional inference of table literal expressions
### Native Code Generation
* Initial steps toward a shared code allocator
---
### Internal Contributors
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
# What's Changed
* Fix a case where the stack wasn't completely cleaned up where
`debug.info` errored when passed `"f"` option and a thread.
* Fix a case of uninitialized field in `luaF_newproto`.
### New Type Solver
* When a local is captured in a function, don't add a new entry to the
`DfgScope::bindings` if the capture occurs within a loop.
* Fix a poor performance characteristic during unification by not trying
to simplify an intersection.
* Fix a case of multiple constraints mutating the same blocked type
causing incorrect inferences.
* Fix a case of assertion failure when overload resolution encounters a
return typepack mismatch.
* When refining a property of the top `table` type, we no longer signal
an unknown property error.
* Fix a misuse of free types when trying to infer the type of a
subscript expression.
* Fix a case of assertion failure when trying to resolve an overload
from `never`.
### Native Code Generation
* Fix dead store optimization issues caused by partial stores.
---
### Internal Contributors
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: David Cope <dcope@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
---------
Co-authored-by: Aaron Weiss <aaronweiss@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?
* Luau allocation scheme was changed to handle allocations in 513-1024
byte range internally without falling back to global allocator
* coroutine/thread creation no longer requires any global allocations,
making it up to 15% faster (vs libc malloc)
* table construction for 17-32 keys or 33-64 array elements is up to 30%
faster (vs libc malloc)
### New Type Solver
* Cyclic unary negation type families are reduced to `number` when
possible
* Class types are skipped when searching for free types in unifier to
improve performance
* Fixed issues with table type inference when metatables are present
* Improved inference of iteration loop types
* Fixed an issue with bidirectional inference of method calls
* Type simplification will now preserve error suppression markers
### Native Code Generation
* Fixed TAG_VECTOR skip optimization to not break instruction use counts
(broken optimization wasn't included in 614)
* Fixed missing side-effect when optimizing generic loop preparation
instruction
---
### Internal Contributors
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Lily Brown <lbrown@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>
# What's changed?
Add program argument passing to scripts run using the Luau REPL! You can
now pass `--program-args` (or shorthand `-a`) to the REPL which will
treat all remaining arguments as arguments to pass to executed scripts.
These values can be accessed through variadic argument expansion. You
can read these values like so:
```
local args = {...} -- gets you an array of all the arguments
```
For example if we run the following script like `luau test.lua -a test1
test2 test3`:
```
-- test.lua
print(...)
```
you should get the output:
```
test1 test2 test3
```
### Native Code Generation
* Improve A64 lowering for vector operations by using vector
instructions
* Fix lowering issue in IR value location tracking!
- A developer reported a divergence between code run in the VM and
Native Code Generation which we have now fixed
### New Type Solver
* Apply substitution to type families, and emit new constraints to
reduce those further
* More progress on reducing comparison (`lt/le`)type families
* Resolve two major sources of cyclic types in the new solver
### Miscellaneous
* Turned internal compiler errors (ICE's) into warnings and errors
-------
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: 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>
# What's changed?
* Compiler now targets bytecode version 5 by default, this includes
support for vector type literals and sub/div opcodes with a constant on
lhs
### New Type Solver
* Normalizer type inhabitance check has been optimized
* Added ability to reduce cyclic `and`/`or` type families
### Native Code Generation
* `CodeGen::compile` now returns more specific causes of a code
generation failure
* Fixed linking issues on platforms that don't support unwind frame data
registration
---
### Internal Contributors
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Aviral Goel <agoel@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>
# What's changed?
### Native Code Generation
* Fixed an UAF relating to reusing a hash key after a weak table has
undergone some GC.
* Fixed a bounds check on arm64 to allow access to the last byte of a
buffer.
### New Type Solver
* Type states now preserves error-suppression, i.e. `local x: any = 5`
and `x.foo` does not error.
* Made error-suppression logic in subtyping more accurate.
* Subtyping now knows how to reduce type families.
* Fixed function call overload resolution so that the return type
resolves to the correct overload.
* Fixed a case where we attempted to reduce irreducible type families a
few too many times, leading to duplicate errors.
* Type checker needs to type check annotations in function signatures to
be able to report errors relating to those annotations.
* Fixed an UAF from a pointer to stack-allocated data in Subtyping's
`explainReasonings`.
### Nonstrict Type Checker
* Fixed a crash when calling a checked function of the form `math.abs`
with an incorrect argument type.
* Fixed a crash when calling a checked function with a number of
arguments that did not exactly match the number of parameters required.
---
### Internal Contributors
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
---------
Co-authored-by: Aaron Weiss <aaronweiss@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>
Currently calling `luaL_sandbox` on Lua instance without loaded strlib
causes crash (assertion).
It happens because inside `luaL_sandbox` there is no check that
metatable for strings is present.
# What's changed?
* Check interrupt handler inside the pattern match engine to eliminate
potential for programs to hang during string library function execution.
* Allow iteration over table properties to pass the old type solver.
### Native Code Generation
* Use in-place memory operands for math library operations on x64.
* Replace opaque bools with separate enum classes in IrDump to improve
code maintainability.
* Translate operations on inferred vectors to IR.
* Enable support for debugging native-compiled functions in Roblox
Studio.
### New Type Solver
* Rework type inference for boolean and string literals to introduce
bounded free types (bounded below by the singleton type, and above by
the primitive type) and reworked primitive type constraint to decide
which is the appropriate type for the literal.
* Introduce `FunctionCheckConstraint` to handle bidirectional
typechecking for function calls, pushing the expected parameter types
from the function onto the arguments.
* Introduce `union` and `intersect` type families to compute deferred
simplified unions and intersections to be employed by the constraint
generation logic in the new solver.
* Implement support for expanding the domain of local types in
`Unifier2`.
* Rework type inference for iteration variables bound by for in loops to
use local types.
* Change constraint blocking logic to use a set to prevent accidental
re-blocking.
* Add logic to detect missing return statements in functions.
### 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: Vyacheslav Egorov <vegorov@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?
* Syntax for [read-only and write-only
properties](https://github.com/luau-lang/rfcs/pull/15) is now parsed,
but is not yet supported in typechecking
### New Type Solver
* `keyof` and `rawkeyof` type operators have been updated to match final
text of the [RFC](https://github.com/luau-lang/rfcs/pull/16)
* Fixed issues with cyclic type families that were generated for mutable
loop variables
### Native Code Generation
* Fixed inference for number / vector operation that caused an
unnecessary VM assist
---
### Internal Contributors
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Lily Brown <lbrown@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>
