### What's new
* Light update this week, mostly fast flag cleanups.
### New Solver
* Rename flag to enable new solver from
`DebugLuauDeferredConstraintResolution` to `LuauSolverV2`
* Added support for magic functions for the new type checker (as opposed
to the type inference component)
* Improved handling of `string.format` with magic function improvements
* Cleaning up some of the reported errors by the new type checker
* Minor refactoring of `TypeChecker2.cpp` that happens to make the diff
very hard to read.
---
### 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>
---------
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 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>
# New Type Solver
- Implement bidirectional type inference for higher order functions so
that we can provide a more precise type improving the autocomplete's
human factors.
- We seal all tables, so we changed the stringification to make it a
little lighter on users.
- Fixed a case of array-out-of-bound access.
- Type families no longer depends on `TxnLog` and `Unifier`.
- Type refinements now waits until the free types are sufficiently
solved.
# Native Code Generation
- Remove cached slot lookup for `executeSETTABLEKS` function because it
is a fallback in the event of a cache miss, making the cached slot
lookup redundant.
- Optimized repeated array lookups, e.g. `a[3]` in `a[3] = a[3] / 2` is
done once.
# Misc
- On some platforms, it is necessary to use `gmtime_s` with the
arguments reversed to get the current time. You can now define
`DOCTEST_CONFIG_USE_GMTIME_S` to build and run unit tests on those
platforms.
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Lots of things going on this week:
* Fix a crash that could occur in the presence of a cyclic union. We
shouldn't be creating cyclic unions, but we shouldn't be crashing when
they arise either.
* Minor cleanup of `luau_precall`
* Internal change to make L->top handling slightly more uniform
* Optimize SETGLOBAL & GETGLOBAL fallback C functions.
* https://github.com/Roblox/luau/pull/929
* The syntax to the `luau-reduce` commandline tool has changed. It now
accepts a script, a command to execute, and an error to search for. It
no longer automatically passes the script to the command which makes it
a lot more flexible. Also be warned that it edits the script it is
passed **in place**. Do not point it at something that is not in source
control!
New solver
* Switch to a greedier but more fallible algorithm for simplifying union
and intersection types that are created as part of refinement
calculation. This has much better and more predictable performance.
* Fix a constraint cycle in recursive function calls.
* Much improved inference of binary addition. Functions like `function
add(x, y) return x + y end` can now be inferred without annotations. We
also accurately typecheck calls to functions like this.
* Many small bugfixes surrounding things like table indexers
* Add support for indexers on class types. This was previously added to
the old solver; we now add it to the new one for feature parity.
JIT
* https://github.com/Roblox/luau/pull/931
* Fuse key.value and key.tt loads for CEHCK_SLOT_MATCH in A64
* Implement remaining aliases of BFM for A64
* Implement new callinfo flag for A64
* Add instruction simplification for int->num->int conversion chains
* Don't even load execdata for X64 calls
* Treat opcode fallbacks the same as manually written fallbacks
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
* Work toward affording parallel type checking
* The interface to `LazyType` has changed:
* `LazyType` now takes a second callback that is passed the `LazyType&`
itself. This new callback is responsible for populating the field
`TypeId LazyType::unwrapped`. Multithreaded implementations should
acquire a lock in this callback.
* Modules now retain their `humanReadableNames`. This reduces the number
of cases where type checking has to call back to a `ModuleResolver`.
* https://github.com/Roblox/luau/pull/902
* Add timing info to the Luau REPL compilation output
We've also fixed some bugs and crashes in the new solver as we march
toward readiness.
* Thread ICEs (Internal Compiler Errors) back to the Frontend properly
* Refinements are no longer applied to lvalues
* More miscellaneous stability improvements
Lots of activity in the new JIT engine:
* Implement register spilling/restore for A64
* Correct Luau IR value restore location tracking
* Fixed use-after-free in x86 register allocator spill restore
* Use btz for bit tests
* Finish branch assembly support for A64
* Codesize and performance improvements for A64
* The bit32 library has been implemented for arm and x64
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
* Fixed exported types not being suggested in autocomplete
* `T...` is now convertible to `...any` (Fixes
https://github.com/Roblox/luau/issues/767)
* Fixed issue with `T?` not being convertible to `T | T` or `T?`
(sometimes when internal pointer identity is different)
* Fixed potential crash in missing table key error suggestion to use a
similar existing key
* `lua_topointer` now returns a pointer for strings
C++ API Changes:
* `prepareModuleScope` callback has moved from TypeChecker to Frontend
* For LSPs, AstQuery functions (and `isWithinComment`) can be used
without full Frontend data
A lot of changes in our two experimental components as well.
In our work on the new type-solver, the following issues were fixed:
* Fixed table union and intersection indexing
* Correct custom type environments are now used
* Fixed issue with values of `free & number` type not accepted in
numeric operations
And these are the changes in native code generation (JIT):
* arm64 lowering is almost complete with support for 99% of IR commands
and all fastcalls
* Fixed x64 assembly encoding for extended byte registers
* More external x64 calls are aware of register allocator
* `math.min`/`math.max` with more than 2 arguments are now lowered to IR
as well
* Fixed correctness issues with `math` library calls with multiple
results in variadic context and with x64 register conflicts
* x64 register allocator learnt to restore values from VM memory instead
of always using stack spills
* x64 exception unwind information now supports multiple functions and
fixes function start offset in Dwarf2 info
* `table.sort` was improved further. It now guarentees N*log(N) time
complexity in the worst case.
* Fix https://github.com/Roblox/luau/issues/880
We are also working on fixing final bugs and crashes in the new type
solver.
On the CodeGen front we have a few things going on:
* We have a smarter register allocator for the x86 JIT
* We lower more instructions on arm64
* The vector constructor builtin is now translated to IR
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
* Fix#817
* Fix#850
* Optimize math.floor/ceil/round with SSE4.1
* Results in a ~7-9% speedup on the math-cordic benchmark.
* Optimized table.sort.
* table.sort is now ~4.1x faster (when not using a predicate) and ~2.1x
faster when using a simple predicate. Performance may improve further in
the future.
* Reorganize the memory ownership of builtin type definitions.
* This is a small initial step toward affording parallel typechecking.
The new type solver is coming along nicely. We are working on fixing
crashes and bugs.
A few major changes to native codegen landed this week:
* Fixed lowering of Luau IR mod instruction when first argument is a
constant
* Added VM register data-flow/capture analysis
* Fixed issues with optimizations in unreachable blocks
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
* Fixed garbage data in module scopes when type graph is not retained
* LOP_MOVE with the same source and target registers is no longer
generated (Fixes https://github.com/Roblox/luau/issues/793)
* Fixed unions of `nil` types displaying as `?`
* Internal normalization now handles class types which can make
previously failing (incorrectly) sub-typing checks to succeed
* Support `["prop"]` syntax on class definitions in definition files.
(#704)
* Improve type checking performance for complex overloaded functions
* Fix rare cases of incorrect stack traces for out of memory errors at
runtime
- Remove type definitions of
`utf8.nfcnormalize`/`nfdnormalize`/`graphemes` that aren't supported by
standalone Luau library
- Add `lua_costatus` to retrieve extended thread status (similar to
`coroutine.status`)
- Improve GC sweeping performance (2-10% improvement on allocation-heavy
benchmarks)
- Fix autocomplete not suggesting globals defined after the cursor (fixes#622)
- Improve type checker stability
- Reduce parser C stack consumption which fixes some stack overflow crashes on deeply nested sources
- Improve performance of bit32.extract/replace when width is implied (~3% faster chess)
- Improve performance of bit32.extract when field/width are constants (~10% faster base64)
- Heap dump now annotates thread stacks with local variable/function names
* Fix free Luau type being fully overwritten by 'any' and causing UAF
* Fix lua_clonefunction implementation replacing top instead of pushing
* Falsey values other than false can now narrow refinements
* Fix lua_getmetatable, lua_getfenv not waking thread up
* FIx a case where lua_objlen could push a new string without thread wakeup or GC
* Moved Luau math and bit32 definitions to definition file
* Improve Luau parse recovery of incorrect return type token
* Adds a currently unused x86-64 assembler as a prerequisite for possible future JIT compilation
* Fix a bug in table iteration (closes Possible table iteration bug #504)
* Improved warning method when function is used as a type
* Fix a bug with unsandboxed iteration with pairs()
* Type of coroutine.status() is now a union of value types
* Bytecode output for tests/debugging now has labels
* Improvements to loop unrolling cost estimation
* Report errors when the key obviously doesn't exist in the table
- Improve refinement support for unions, in particular it's now possible to implement tagged unions as a union of tables where individual branches use a string literal type for one of the fields.
- Fix `string.split` type information
- Optimize `select(_, ...)` to run in constant time (~2.7x faster on VariadicSelect benchmark)
- Improve debug line information for multi-line assignments
- Improve compilation of table literals when table keys are constant expressions/variables
- Use forward GC barrier for `setmetatable` which slightly accelerates GC progress
- Rework transaction log used for type checking which should result in more robust type checking internals with fewer bugs
- Reduce the amount of memory consumed by type checker on large module graphs
- Type checker now errors on attempts to change the type of imported module fields
- The return type of newproxy is now any (fixes#296)
- Implement new number printing algorithm (Schubfach) which makes tostring() produce precise (round-trippable) and short decimal output up to 10x faster
- Fix lua_Debug::linedefined to point to the line with the function definition instead of the first statement (fixes#265)
- Fix minor bugs in Tab completion in Repl
- Repl now saves/restores command history in ~/.luau_history
- Fix some cases where type checking would overflow the native stack
- Improve autocomplete behavior when assigning a partially written function call (not currently exposed through command line tools)
- Improve autocomplete type inference feedback for some expressions where previously the type would not be known
- Improve quantification performance during type checking for large types
- Improve type checking for table literals when the expected type of the table is known because of a type annotation
- Fix type checking errors in cases where required module has errors in the resulting type
- Fix debug line information for multi-line chained call sequences (Add function name information for "attempt to call a nil value" #255)
- lua_newuserdata now takes 2 arguments to match Lua/LuaJIT APIs better; lua_newuserdatatagged should be used if the third argument was non-0.
- lua_ref can no longer be used with LUA_REGISTRYINDEX to prevent mistakes when migrating Lua FFI (Inconsistency with lua_ref #247)
- Fix assertions and possible crashes when executing script code indirectly via metatable dispatch from lua_equal/lua_lessthan/lua_getfield/etc. (Hitting a crash in an assert after lua_equal is called. #259)
- Fix flamegraph scripts to run under Python 2
- Type mismatch errors now show detailed information for compound types, highlighting the mismatching component
- Fix string.pack bug on ARM when packing negative numbers using unsigned formats
- Implement bit32.countlz/countrz (RFC RFC: bit32.countlz/countrz #89)
- Minor compiler throughput optimization (~2% faster compilation)
- Improve transpiler behavior for edge cases and better test coverage (not exposed through CLI at the moment)
- Improve error recovery when parsing invalid assignments
- Build fixes for fuzzing targets
- A series of major optimizations to type checking performance on complex
programs/types (up to two orders of magnitude speedup for programs
involving huge tagged unions)
- Fix a few issues encountered by UBSAN (and maybe fix s390x builds)
- Fix gcc-11 test builds
- Fix a rare corner case where luau_load wouldn't wake inactive threads
which could result in a use-after-free due to GC
- Fix CLI crash when error object that's not a string escapes to top level
- Fix Makefile suffixes on macOS
Co-authored-by: Rodactor <rodactor@roblox.com>
Changes:
- Support for time tracing for analysis/compiler (not currently exposed
through CLI)
- Support for type pack arguments in type aliases (#83)
- Basic support for require(path) in luau-analyze
- Add a lint warning for table.move with 0 index as part of
TableOperation lint
- Remove last STL dependency from Luau.VM
- Minor VS2022 performance tuning
Co-authored-by: Rodactor <rodactor@roblox.com>
