SamandClaude Fable 5
d7f4c59fa8
- `--surface` re-runs the comparison against the captured in-world global table on demand, and `--surface-dump` writes our raw side for any tool to join — a one-shot measurement stops drifting - CreateFrame with an unresolvable template raises exactly as the client does, instead of handing back a bare frame; `inherits=` is one name, matched case-insensitively - CreateFontString and CreateTexture honour their third argument — 49 corpus call sites were passing an inherit into the void - the addon-message inbound byte map is corrected (a test had agreed with the wrong constants), and the group-loot roll template publishes under the reference's own name Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
79 lines
4.5 KiB
Markdown
79 lines
4.5 KiB
Markdown
# benilla's `lua-src` fork — what differs from upstream, and how to check
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Upstream: [`mlua-rs/lua-src-rs`](https://github.com/mlua-rs/lua-src-rs), MIT, version `550.0.0` —
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the version mlua 0.11 resolves to. Wired in through `[patch.crates-io]` in the workspace root.
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## Why a fork exists at all
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The 1.12 addon corpus is Lua **5.0** code. It uses the iterator-less generic-for:
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```lua
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for k, v in someTable do ... end -- no pairs(), no iterator function
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```
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**183 of 218 corpus addons are reached by it** (118 carry it, 65 inherit it through a declared
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dependency), across 1,163 sites. On stock Lua 5.1 it raises `attempt to call a table value`, and it
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is the **first session-start error for 60 of 218 addons — three quarters of everything that breaks
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once the client is actually running**, eleven times the next cause.
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Lua 5.1 removed it at the **opcode** level, which is why no layer above the VM can reach it. Every
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other dialect gap this project has closed was reachable from inside Lua — `table.setn` is a library
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function, `bit` is a library, `print` is a global (decisions 1194, 1196). This one is not:
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- a `__call` metamethod would work, but the tables are the addon's own and Lua 5.1 has no
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per-*type* default metatable for tables;
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- rewriting the chunk source means parsing Lua with a regex to tell `in t do` from `in pairs(t) do`,
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and getting that wrong changes behaviour silently;
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- there is no `lua50` backend — `lua-src` ships 5.1 through 5.5 and every one of them removed it.
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## What is NOT being done
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**benilla is not adopting Lua 5.0.** We stay on 5.1.5 and restore the behaviour of a single opcode
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that Lua itself shipped and labelled `/* for compatibility only */`. Every other 5.1 fix, and the
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whole of mlua's surface, stay exactly as upstream. That is a far smaller commitment than a version
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downgrade, and it is the entire reason this is a one-hunk fork rather than a vendored 5.0.
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## The delta, and the command that proves it
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**Current state: two hunks, in two files.** `src/lib.rs` additionally differs by having Lua
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5.2/5.3/5.4/5.5 stripped from the `Version` enum (with their source trees deleted) — benilla builds
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5.1 and only 5.1, and a fork that still *offered* the other four would answer a request for one with
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a missing directory at build time instead of a compile error.
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| file | hunk | why | record |
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|---|---|---|---|
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| `lvm.c` | 5.0's `OP_TFORPREP` table→`next` substitution, folded into the top of `OP_TFORLOOP` | `for k, v in someTable do` raised "attempt to call a table value"; it was the first session-start error for **60** corpus addons | 1215 |
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| `luaconf.h` | `LUA_COMPAT_LSTR` `1` → `2` | 5.1 kept 5.0's nesting machinery and put an advisory error in front of it; two corpus addons died on "nesting of `[[...]]` is deprecated" | — |
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The ordering was deliberate and it held: the fork landed **inert**, byte-identical to upstream, so
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the build pipeline was proven transparent *before* any behavioural payload went into it — and when
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the suite then moved, the patch was the only thing that could have moved it. Both hunks are measured
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against the 218-addon corpus rather than argued: the long-string one alone took loaded 134 → 139 and
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survivors 99 → 104.
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To verify the Lua sources against upstream at any time:
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```sh
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# 550.0.0 is the pinned version; adjust the path if cargo's registry hash differs.
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diff -r third_party/lua-src/lua-5.1.5 \
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~/.cargo/registry/src/*/lua-src-550.0.0/lua-5.1.5
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```
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That must print **exactly** the two hunks in the table above and nothing else. If it ever prints
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more, something crept in.
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## Status of the payload
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**Landed.** The reverse-engineering answer this was deliberately blocked on came back from
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`wow-5875-re` (`system/ui/scratch/lua-generic-for.md`) and is what the `lvm.c` comment cites, detail
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by detail: a **bare type-tag** test that never consults a metatable (so a table carrying `__call`
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still gets `next`), the **global** `next` read raw and fetched fresh at every loop entry (so an addon
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assigning `next = myfn` changes every later generic-for in the session), and userdata *not*
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substituted.
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Waiting was the right call twice over. Checking stock 5.0 first corrected two assumptions the
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project had already written down — the substitution happens in `OP_TFORPREP`, an opcode 5.1 deleted,
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*not* in `OP_TFORLOOP`; and the test is a bare `ttistable` with no `__call` check. Stock 5.0 was
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corroboration, never the authority: the client links 5.0 but may be modified, and only the byte-read
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of the client settles what it actually does.
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