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CC-Tweaked/doc/reference/feature_compat.md
Jonathan Coates 784e623776
Update Cobalt to 0.8.0
- Update Cobalt to 0.8.0, switching our Lua version to 5.2(ish).

 - Remove our `load` wrapper, as we no longer need to inject _ENV into
   the enviroment table.

 - Update the parser to handle labels and goto. This doesn't check that
   gotos are well formed, but at least means the parser doesn't fall
   over on them.

 - Update our docs to reflect the changes to Cobalt.
2023-11-08 18:42:17 +00:00

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---
module: [kind=reference] feature_compat
---
<!--
SPDX-FileCopyrightText: 2022 The CC: Tweaked Developers
SPDX-License-Identifier: MPL-2.0
-->
# Lua 5.2/5.3 features in CC: Tweaked
CC: Tweaked is based off of the Cobalt Lua runtime, which uses Lua 5.2. However, Cobalt and CC:T implement additional
features from Lua 5.2 and 5.3 (as well as some deprecated 5.0 and 5.1 features). This page lists all of the
compatibility for these newer versions.
## Lua 5.2
| Feature | Supported? | Notes |
|---------------------------------------------------------------|------------|-------------------------------------------------------------------|
| `goto`/labels | ✔ | |
| `_ENV` | ✔ | |
| `\z` escape | ✔ | |
| `\xNN` escape | ✔ | |
| Hex literal fractional/exponent parts | ✔ | |
| Empty statements | ✔ | |
| `__len` metamethod | ✔ | |
| `__ipairs` metamethod | ❌ | Deprecated in Lua 5.3. `ipairs` uses `__len`/`__index` instead. |
| `__pairs` metamethod | ✔ | |
| `bit32` library | ✔ | |
| `collectgarbage` isrunning, generational, incremental options | ❌ | `collectgarbage` does not exist in CC:T. |
| New `load` syntax | ✔ | |
| `loadfile` mode parameter | ✔ | Supports both 5.1 and 5.2+ syntax. |
| Removed `loadstring` | ❌ | |
| Removed `getfenv`, `setfenv` | 🔶 | Only supports closures with an `_ENV` upvalue. |
| `rawlen` function | ✔ | |
| Negative index to `select` | ✔ | |
| Removed `unpack` | ❌ | |
| Arguments to `xpcall` | ✔ | |
| Second return value from `coroutine.running` | ✔ | |
| Removed `module` | ✔ | |
| `package.loaders` -> `package.searchers` | ❌ | |
| Second argument to loader functions | ✔ | |
| `package.config` | ✔ | |
| `package.searchpath` | ✔ | |
| Removed `package.seeall` | ✔ | |
| `string.dump` on functions with upvalues (blanks them out) | ❌ | `string.dump` is not supported |
| `string.rep` separator | ✔ | |
| `%g` match group | ❌ | |
| Removal of `%z` match group | ❌ | |
| Removed `table.maxn` | ❌ | |
| `table.pack`/`table.unpack` | ✔ | |
| `math.log` base argument | ✔ | |
| Removed `math.log10` | ❌ | |
| `*L` mode to `file:read` | ✔ | |
| `os.execute` exit type + return value | ❌ | `os.execute` does not exist in CC:T. |
| `os.exit` close argument | ❌ | `os.exit` does not exist in CC:T. |
| `istailcall` field in `debug.getinfo` | ❌ | |
| `nparams` field in `debug.getinfo` | ✔ | |
| `isvararg` field in `debug.getinfo` | ✔ | |
| `debug.getlocal` negative indices for varargs | ❌ | |
| `debug.getuservalue`/`debug.setuservalue` | ❌ | Userdata are rarely used in CC:T, so this is not necessary. |
| `debug.upvalueid` | ✔ | |
| `debug.upvaluejoin` | ✔ | |
| Tail call hooks | ❌ | |
| `=` prefix for chunks | ✔ | |
| Yield across C boundary | ✔ | |
| Removal of ambiguity error | ✔ | |
| Identifiers may no longer use locale-dependent letters | ✔ | |
| Ephemeron tables | ❌ | |
| Identical functions may be reused | ❌ | Removed in Lua 5.4 |
| Generational garbage collector | ❌ | Cobalt uses the built-in Java garbage collector. |
## Lua 5.3
| Feature | Supported? | Notes |
|---------------------------------------------------------------------------------------|------------|---------------------------|
| Integer subtype | ❌ | |
| Bitwise operators/floor division | ❌ | |
| `\u{XXX}` escape sequence | ✔ | |
| `utf8` library | ✔ | |
| removed `__ipairs` metamethod | ✔ | |
| `coroutine.isyieldable` | ✔ | |
| `string.dump` strip argument | ✔ | |
| `string.pack`/`string.unpack`/`string.packsize` | ✔ | |
| `table.move` | ✔ | |
| `math.atan2` -> `math.atan` | ❌ | |
| Removed `math.frexp`, `math.ldexp`, `math.pow`, `math.cosh`, `math.sinh`, `math.tanh` | ❌ | |
| `math.maxinteger`/`math.mininteger` | ❌ | |
| `math.tointeger` | ❌ | |
| `math.type` | ❌ | |
| `math.ult` | ❌ | |
| Removed `bit32` library | ❌ | |
| Remove `*` from `file:read` modes | ✔ | |
| Metamethods respected in `table.*`, `ipairs` | ✔ | |
## Lua 5.0
| Feature | Supported? | Notes |
|----------------------------------|------------|--------------------------------------------------|
| `arg` table | 🔶 | Only set in the shell - not used in functions. |
| `string.gfind` | ✔ | Equal to `string.gmatch`. |
| `table.getn` | ✔ | Equal to `#tbl`. |
| `table.setn` | ❌ | |
| `math.mod` | ✔ | Equal to `math.fmod`. |
| `table.foreach`/`table.foreachi` | ✔ | |
| `gcinfo` | ❌ | Cobalt uses the built-in Java garbage collector. |