## 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>
Another week, another release!
## Analysis
- Do not warn on unknown `require`s in non-strict mode.
- Improve `Luau::dump`'s output for `DenseHashMap`.
- Raise type checking errors when we would otherwise be leaking internal
error types from modules.
- Fix a crash that would sometimes occur when calling a function with an
incomplete type.
- Replace uses of `FFlag::LuauSolverV2` in `ClonePublicInterface` with a
`solverMode` field.
- Limit the number of constraints that can be dynamically created to
fail more gracefully in complex cases.
- Fix#1932.
---------
Co-authored-by: Alexander Youngblood <ayoungblood@roblox.com>
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: 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?
Another somewhat quiet week! Don't let the large PR fool you, this is
mostly ...
## New Solver
* The code for type functions has been re-organized: instead of
_everything_ living in `TypeFunction.h` and `TypeFunction.cpp`, we now
have separate files for the type function inference machinery
(`TypeFunction.h`), definitions of built-in type functions
(`BuiltinTypeFunctions.h`), and the implementation of user defined type
functions (`UserDefinedTypeFunction.h`).
* Refinements against `*no-refine*`, a sentinel type indicating that no
refinements should occur, are now _always_ resolved, even if the target
of the refinement would be otherwise pending, such as another type
function.
## Autocomplete
* Fixed autocomplete to prefer table property completion to string
singleton completion. In the below example, the types associated with
each member of `foo` will be displayed in autocomplete popups.
```
local foo = {
["Item/Foo"] = 42,
["Item/Bar"] = "it's true",
["Item/Baz"] = true,
}
foo["|"] -- cursor at `|`
```
## Native Codegen
* Fixed native compilation lowering of the new global lookup
instruction, which caused code generation to fail with an error or to
evaluate incorrect results. Issue affected 678-681 releases when all
flags were enabled.
---
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: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
# What's Changed?
Short week, so a slightly shorter release! This one has been focused on
improving polish in fragment autocomplete and the new solver.
## New Type Solver
* Fix a bug where we didn't infer self types correctly under
bidirectional type inference.
* Improve the memory consumption of the new solver by reducing the
number of expensive allocations performed by `Substitution`.
* The New non strict Mode shouldn't issue errors when we call checked
functions with `never` values.
* Extend the number of cases in which the new non strict mode can report
unknown symbols.
* Fix a bug where `and` and `or` expressions didn't correctly forward
information computed by their operands. This should allow more programs
using these expressions to complete typechecking correctly.
* Small performance improvements for `Generalization`
## Fragment Autocomplete
* Fragment autocomplete provides richer autofill information when typing
`self.|`
* Fragment autocomplete now uses refinement information computed in the
new solver to provide more accurate incremental completion.
## Code Generation
* Fix a bug where Codegen could sometimes try to execute a
non-executable page
---
Co-authored-by: Ariel Weiss <aaronweiss@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>
---------
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: 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 includes many changes to bring the behaviours of the Old and
New Luau Type Solver more in line.
* The old solver now stringifies tables identically to the new solver.
Sealed tables are stringified as `{ ... }` and unsealed tables are
represented by `{| ... |}`, regardless of your choice of solver.
## New Type Solver
* Miscellaneous fixes to make the Luau Frontend able to dynamically
toggle which solve is used.
* Small fixes to reduce instances of nondeterminism of the New Type
Solver.
* Issue an error when a function that has multiple non-viable overloads
is used.
* Subtyping now returns more information about the generics for type
inference to consume.
* Stop stuck type-functions from blocking type inference. This should
lead to fewer instances of 'type inference failed to complete'.
## Fragment Autocomplete
* Fixed a bug where incremental autocomplete wouldn't be able to provide
results directly on a required module script.
`require(script.Module).{request completions here}` will now recommend
the properties returned by the required object.
---
Co-authored-by: Andy Friesen <afriesen@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: Vighnesh Vijay <vvijay@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?
We've been hard at work fixing bugs in the new type solver and getting
it ready to go!
## Native Codegen
* Specialized Luau Codegen instruction for fetching an import.
As a reminder, an import is an expression like `global.thing` and covers
stuff like libraries without fastcalls `coroutine.resume`) and atomic
extern libraries.
## New Type Solver
* Fix an issue that prevented eager generalization from working properly
with OO styled code.
* Avoid copying uninitialized memory in Luau attribute parsing
* Improve type inference of unsealed tables.
* This fixes https://github.com/luau-lang/luau/issues/1838
* and https://github.com/luau-lang/luau/issues/1859
* Infer potential singleton string keys in autocomplete when the
expected index type is a union type.
* Avoid creating cyclic types when reducing types of the form `t1 where
t1 = refine<T, t1, Y>`
* The type cloner now does the same thing for the new and old solvers.
* Properly infer polarity (aka variance) for divergent table properties.
(ie tables whose read type and write type are not the same)
* Crash fixes.
---------
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>
# 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>
We're back on track after the long weekend!
## General
- `clang-format`ed new code. Keep your code tidy!
- Disable some Luau tests that are broken currently.
- Enable fragment autocomplete to do tagged union completion for modules
typechecked in the old solver.
## New Type Solver
- Fix false positives on generic type packs in non-strict mode.
- Update type signature of `setmetatable` to be `<T, MT>(T, MT) ->
setmetatable<T, MT>`.
- Make local type aliases available in type functions. For example:
```
type Foo = number
type Array<T> = {T}
type function Bar(t)
return types.unionof(Foo, Array(t))
end
```
## VM/Runtime
- Make sure `lua_unref` doesn't accept refs which did not exist in the
table.
---
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: 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: 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
- 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>
# What's Changed?
Hi there, folks! It's been another busy week in the type mines, trying
to bring you all the very best type inference system we can. We've got a
bunch of updates to large pain points across the new type solver, and
our next big update (currently under a debug flag) improving type
generalization is finally nearing completion (and should hopefully
eliminate quite a lot of "type solver failed to complete" errors). We've
also continued polishing both the CST Parser and the `Luau.Require`
library we introduced a few releases ago based on user feedback and bug
reports, and we're really happy with how they're turning out.
# Parser
- Fixes a bug in the CST tooling where the spacing on return type
annotations for functions was not being printed correctly.
- Resolves some issues with the JSON encoding of `AstGenericType` and
`AstGenericTypePack`
# Runtime
- Implements support for yielding requires in `Luau.Require` library.
- Improves the error messages for require-by-string to include the chunk
name that was problematic where possible and the overall require path
that failed to be required.
- Fixes a bug that prevented the use of `require` within C functions and
`pcall`.
- Adds an API to support selectively removing chunks from the require
cache in `Luau.Require`
- Adds an API to support clearing the entire require cache in
`Luau.Require`
# New Type Solver
- Fixes a crash in the new non-strict mode when visiting function return
types in incomplete ASTs (e.g. during editing).
- Improves type simplification to support intersections of tables with
extern types, resolving _one_ of the causes of frequent refinements
unexpectedly leading to `never`.
- Improves type inference to better understand diverging branches in
functions, reducing false negatives where the type system fails to learn
that a binding must now always be initialized.
- Fixes a typo in the type definitions for user-defined function types
where the `intersection` tag was misspelled.
- Improves the overall accuracy of free type tracking during constraint
solving, leading to better inference results overall.
- Implements `types.optional` as a new library function for user-defined
type functions to make it easier to union a type with `nil`.
- Resolves a number of bugs caused by local type inference expanding the
domain of upvalues
# 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: Talha Pathan <tpathan@roblox.com>
Co-authored-by: Varun Saini <vsaini@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@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: Andy Friesen <afriesen@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>
## New Type Solver
1. Update resolved types for singleton unions and intersections to avoid
crashing when type checking type assertions.
2. Generalize free return type pack of a function type inferred at call
site to ensure that the free type does not leak to another module.
3. Fix crash from cyclic indexers by reducing if possible or producing
an error otherwise.
4. Fix handling of irreducible type functions to prevent type inference
from failing.
5. Fix handling of recursive metatables to avoid infinite recursion.
## New and Old Type Solver
Fix accidental capture of all exceptions in multi-threaded typechecking
by converting all typechecking exceptions to `InternalCompilerError` and
only capturing those.
## Fragment Autocomplete
1. Add a block based diff algorithm based on class index and span for
re-typechecking. This reduces the granularity of fragment autocomplete
to avoid flakiness when the fragment does not have enough type
information.
2. Fix bugs arising from incorrect scope selection for autocompletion.
## Roundtrippable AST
Store type alias location in `TypeFun` class to ensure it is accessible
for exported types as part of the public interface.
## Build System
1. Bump minimum supported CMake version to 3.10 since GitHub is phasing
out the currently supported minimum version 3.0, released 11 years ago.
2. Fix compilation when `HARDSTACKTESTS` is enabled.
## Miscellaneous
Flag removals and cleanup of unused code.
## 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: Talha Pathan <tpathan@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
## External Contributors
Thanks to [@grh-official](https://github.com/grh-official) for PR #1759
**Full Changelog**:
https://github.com/luau-lang/luau/compare/0.667...0.668
---------
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: Vighnesh <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Ariel Weiss <aaronweiss@roblox.com>
After a very auspicious release last week, we have a new bevy of changes
for you!
## What's Changed
### Deprecated Attribute
This release includes an implementation of the `@deprecated` attribute
proposed in [this
RFC](https://rfcs.luau.org/syntax-attribute-functions-deprecated.html).
It relies on the new type solver to propagate deprecation information
from function and method AST nodes to the corresponding type objects.
These objects are queried by a linter pass when it encounters local,
global, or indexed variables, to issue deprecation warnings. Uses of
deprecated functions and methods in recursion are ignored. To support
deprecation of class methods, the parser has been extended to allow
attribute declarations on class methods. The implementation does not
support parameters, so it is not currently possible for users to
customize deprecation messages.
### General
- Add a limit for normalization of function types.
### New Type Solver
- Fix type checker to accept numbers as concat operands (Fixes#1671).
- Fix user-defined type functions failing when used inside type
aliases/nested calls (Fixes#1738, Fixes#1679).
- Improve constraint generation for overloaded functions (in part thanks
to @vvatheus in #1694).
- Improve type inference for indexers on table literals, especially when
passing table literals directly as a function call argument.
- Equate regular error type and intersection with a negation of an error
type.
- Avoid swapping types in 2-part union when RHS is optional.
- Use simplification when doing `~nil` refinements.
- `len<>` now works on metatables without `__len` function.
### AST
- Retain source information for `AstTypeUnion` and
`AstTypeIntersection`.
### Transpiler
- Print attributes on functions.
### Parser
- Allow types in indexers to begin with string literals by @jackdotink
in #1750.
### Autocomplete
- Evaluate user-defined type functions in ill-formed source code to
provide autocomplete.
- Fix the start location of functions that have attributes.
- Implement better fragment selection.
### 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>
**Full Changelog**:
https://github.com/luau-lang/luau/compare/0.666...0.667
---------
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>
Another week, another release. Happy spring! 🌷
## New Type Solver
- Add typechecking and autocomplete support for user-defined type
functions!
- Improve the display of type paths, making type mismatch errors far
more human-readable.
- Enhance various aspects of the `index` type function: support function
type metamethods, fix crashes involving cyclic metatables, and forward
`any` types through the type function.
- Fix incorrect subtyping results involving the `buffer` type.
- Fix crashes related to typechecking anonymous functions in nonstrict
mode.
## AST
- Retain source information for type packs, functions, and type
functions.
- Introduce `AstTypeOptional` to differentiate `T?` from `T | nil` in
the AST.
- Prevent the transpiler from advancing before tokens when the AST has
errors.
## Autocomplete
- Introduce demand-based cloning and better module isolation for
fragment autocomplete, leading to a substantial speedup in performance.
- Guard against recursive unions in `autocompleteProps`.
## Miscellaneous
- #1720 (thank you!)
## 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: Talha Pathan <tpathan@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@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>
With gcc 15, the C++ Standard Library no longer includes other headers
that were internally used by the library. In Luau's case the missing
header is `<stdint.h>`
Downstream Gentoo bug: https://bugs.gentoo.org/938122
Signed-off-by: Kostadin Shishmanov <kostadinshishmanov@protonmail.com>
---------
Co-authored-by: vegorov-rbx <75688451+vegorov-rbx@users.noreply.github.com>
As always, a weekly Luau update!
This week we have further improvements to new type solver, fixing a few
of the popular issues reported. The fragment autocomplete is even more
stable and we believe it's ready for broader use.
Aside from that we have a few general fixes/improvements:
* Fixed data race when multi-threaded typechecking is used, appearing as
a random crash at the end of typechecking
* AST data is now available from `Luau::Module`
## New Type Solver
* Fixed type refinements made by function calls which could attach `nil`
as an option of a type before (Fixes#1528)
* Improved bidirectional typechecking in tables (Fixes#1596)
* Fixed normalization of negated types
* `getmetatable()` on `any` type should no longer report an error
## Fragment Autocomplete
* Fixed auto-complete suggestions being provided inside multiline
comments
* Fixed an assertion failure that could happen when old type solver was
used
* Fixed issues with missing suggestions when multiple statements are on
the same line
* Fixed memory safety issues
## Internal Contributors
Co-authored-by: Andy Friesen <afriesen@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>
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 new
This update brings improvements to the new type solver, roundtrippable
AST parsing mode and closes multiple issues reported in this repository.
* `require` dependency tracing for non-string requires now supports `()`
groups in expressions and types as well as an ability to type annotate a
value with a `typeof` of a different module path
* Fixed rare misaligned memory access in Compiler/Typechecker on 32 bit
platforms (Closes#1572)
## New Solver
* Fixed crash/UB in subtyping of type packs (Closes#1449)
* Fixed incorrect type errors when calling `debug.info` (Closes#1534
and Resolves#966)
* Fixed incorrect boolean and string equality comparison result in
user-defined type functions (Closes#1623)
* Fixed incorrect class types being produced in user-defined type
functions when multiple classes share the same name (Closes#1639)
* Improved bidirectional typechecking for table literals containing
elements that have not been solved yet (Closes#1641)
## Roundtrippable AST
* Added source information for `AstStatTypeAlias`
* Fixed an issue with `AstTypeGroup` node (added in #1643) producing
invalid AST json. Contained type is now named 'inner' instead of 'type'
* Fixed end location of the `do ... end` statement
---
Internal Contributors:
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>
This change introduces a flag (`LuauUserTypeFunTypeofReturnsType`) that,
when enabled, sets `__type` on the type userdata's metatable to "type".
This behaviour was described in the user-defined type function RFC
(https://rfcs.luau.org/user-defined-type-functions.html), but seems to
have been missed; this change implements that behaviour.
Currently this does not change `typeof(t) == 'type'` emitting an unknown
type warning as I don't trust myself to implement it due to my general
lack of C++ knowledge; this can be worked on later.
# 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>
# General
This release introduces initial work on a Roundtrippable AST for Luau,
and numerous fixes to the new type solver, runtime, and fragment
autocomplete.
## Roundtrippable AST
To support tooling around source code transformations, we are extending
the parser to retain source information so that we can re-emit the
initial source code exactly as the author wrote it. We have made
numerous changes to the Transpiler, added new AST types such as
`AstTypeGroup`, and added source information to AST nodes such as
`AstExprInterpString`, `AstExprIfElse`, `AstTypeTable`,
`AstTypeReference`, `AstTypeSingletonString`, and `AstTypeTypeof`.
## New Type Solver
* Implement `setmetatable` and `getmetatable` type functions.
* Fix handling of nested and recursive union type functions to prevent
the solver from getting stuck.
* Free types in both old and new solver now have an upper and lower
bound to resolve mixed mode usage of the solvers in fragment
autocomplete.
* Fix infinite recursion during normalization of cyclic tables.
* Add normalization support for intersections of subclasses with negated
superclasses.
## Runtime
* Fix compilation error in Luau buffer bit operations for big-endian
machines.
## Miscellaneous
* Add test and bugfixes to fragment autocomplete.
* Fixed `clang-tidy` warnings in `Simplify.cpp`.
**Full Changelog**:
https://github.com/luau-lang/luau/compare/0.659...0.660
---
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>
## 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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## What's Changed
### General
- Allow types of tables to diverge after using `table.clone` (fixes
#1617).
- Allow 2-argument vector.create in Luau.
- Fix a crash when suggesting autocomplete after encountering parsing
errors.
- Add lua_tolstringatom C API which returns the string length (whether
or not the atom exists) and which extends the existing lua_tostringatom
function the same way lua_tolstring/lua_tostring do.
- Luau now retains the DFGs of typechecked modules.
### Magic Functions Migration Note
We've made a change to the API used to define magic functions.
Previously, we had a set of function pointers on each `FunctionType`
that would be invoked by the type inference engine at the correct point.
The problem we'd run into is that they were all `std::function`s, we'd
grown quite a few of them, and Luau allocates tens of thousands of types
as it performs type inference. This adds up to a large amount of memory
for data that isn't used by 99% of types.
To slim things down a bit, we've replaced all of those `std::function`s
with a single `shared_ptr` to a new interface called `MagicFunction`.
This slims down the memory footprint of each type by about 50 bytes.
The virtual methods of `MagicFunction` have roughly 1:1 correspondence
with the old interface, so updating things should not be too difficult:
* `FunctionType::magicFunction` is now `MagicFunction::handleOldSolver`
* `FunctionType::dcrMagicFunction` is now `MagicFunction::infer`
* `FunctionType::dcrMagicRefinement` is now `MagicFunction::refine`
* `FunctionType::dcrMagicTypeCheck` is now `MagicFunction::typeCheck`
**Full Changelog**:
https://github.com/luau-lang/luau/compare/0.657...0.658
---
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>
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During conflict resolution while transferring patches back and forth,
some conflict resolutions may cause differences that are harder to spot.
This process would have also cleaned up differences noted in
https://github.com/luau-lang/luau/pull/1621
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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>
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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.
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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>
benchmark / callgrind (map[branch:main name:luau-lang/benchmark-data], ubuntu-22.04) (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>
# What's Changed
* Support dead store elimination for `STORE_VECTOR` instruction
* Fix parser hang when a separator is used between Luau class
declaration properties
* Provide properties and metatable for built-in vector type definition
to fix type errors
* Fix Fragment Autocomplete to ensure correct parentheses insertion
behavior.
* Add support for 'thread' and 'buffer' primitive types in user-defined
type functions
---------
Co-authored-by: Andy Friesen <afriesen@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>
## 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>
## What's new?
* Add support for mixed-mode type checking, which allows modules checked
in the old type solver to be checked and autocompleted by the new one.
* Generalize `RequireResolver` to support require-by-string semantics in
`luau-analyze`.
* Fix a bug in incremental autocomplete where `DefId`s associated with
index expressions were not correctly picked up.
* Fix a bug that prevented "complex" types in generic parameters (for
example, `local x: X<(() -> ())?>`).
### Issues fixed
* #1507
* #1518
---
Internal Contributors:
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@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>
### What's New?
* Fragment Autocomplete: a new API allows for type checking a small
fragment of code against an existing file, significantly speeding up
autocomplete performance in large files.
### New Solver
* E-Graphs have landed: this is an ongoing approach to make the new type
solver simplify types in a more consistent and principled manner, based
on similar work (see: https://egraphs-good.github.io/).
* Adds support for exporting / local user type functions (previously
they were always exported).
* Fixes a set of bugs in which the new solver will fail to complete
inference for simple expressions with just literals and operators.
### General Updates
* Requiring a path with a ".lua" or ".luau" extension will now have a
bespoke error suggesting to remove said extension.
* Fixes a bug in which whether two `Luau::Symbol`s are equal depends on
whether the new solver is enabled.
---
Internal Contributors:
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: David Cope <dcope@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>
Closes#1492
Tested and working with the test case in the aforementioned issue, along
with the full defs of luau-lsp with no issues or type errors
In normal Luau files, you can use type aliases and type functions before
they are declared. The same extends to declaration files, **except** in
the new solver. The old solver perfectly allows this, and in fact
intentionally adds it:
db809395bf/Analysis/src/TypeInfer.cpp (L1711-L1717)
This causes *much* headache and pain for external projects that make use
of declaration files; namely, luau-lsp generates them from MaximumADHD's
API dump, which is not ordered by dependency. This means silent
error-types popping up everywhere because types are used before they are
declared. The workaround would be to make code to manually reorder class
definitions based on their dependencies with a bunch of code, but this
is clearly not ideal, and won't work for classes dependent on each
other/recursive.
The solution used here is the same as is used for type aliases - the
name binding for the class is given a blocked type before running the
rest of constraint generation on the block. Questions remain:
- Should the logic be split off of `checkAliases`?
- Should a bound type be used, or should the (blocked) binding type be
directly emplaced with the class type? What are the ramifications of
emplacing with the bound versus the raw type? One ramification was
initially ran into through an assertion because the class
`superTy`/`parent` was bound, and several pieces of code assume it is
not, so it had to be made followed.
- Is folllowing `superTy` to set `parent` the correct workaround for the
assertions thrown, or should the code expecting `parent` to be a
ClassType without following it be modified instead to follow `parent`?
- Should `scope->privateTypeBindings` also be checked for the duplicate
error? I would presume so, since having a class with the same name as a
private alias or type function should error as well?
The extraneous whitespace changes are clang-format ones done
automatically that should've been done in the last release - I can
remove them if necessary and let another sync or OSS cleanup commit fix
it.
Closes#1441
Brings behavior to parity with the old solver by filling in
definitionLocation and definitionModuleName for Luau-consuming
programs/libraries to use.
* 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>
