## 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>
# 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>
