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base repository: luau-lang/luau
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head repository: luau-lang/luau
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compare: 0.687
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  • 1 commit
  • 99 files changed
  • 9 contributors

Commits on Aug 15, 2025

  1. Sync to upstream/release/687 (#1954) 

    ## 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>
    @vegorov-rbx @andyfriesen
    @annieetang @aatxe @hgoldstein @skanosue @Vighnesh-V
    9 people authored Aug 15, 2025
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