# 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>
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>
