**A deviation, and the reasoning matters more than the code.** 1.12 raises `Usage:` on a
one-argument `SetPoint`, and that is traced rather than assumed: the `lua_type(L,3)` tag gate
at `0x7a25e6`..`0x7a2620` accepts four tags and an absent argument is none of them, which
this file's own header has said all along. Later clients read it as the default parent at the
same point with no offset, and that is what every Era-era addon writes —
`Cinematic/CameraWheel.lua:243` is `face:SetPoint("CENTER")`.
Allowed because **the real `ClassicAPI.dll` writes that form itself**: its embedded Lua
carries `f:SetPoint("CENTER");` and `tx:SetPoint(q[4]);`, so on the client this build already
announces itself as (`CLASSIC_API_VERSION` is set) the one-argument form has to work, or
ClassicAPI's own windows would not build. Claiming that client and withholding this is the
inconsistent position `stdlib_backport.rs` settled for the stdlib half.
It costs nothing in the ladder because of how it is spelled: the leg resolves to exactly what
the reference's own **three-argument** shorthand does (`RelTarget::DefaultParent`,
`0x7a270e`) — default parent, `rel_point` defaulted to `point`, offsets falling through to
(0, 0). No anchor shape is added; one spelling is mapped onto another the reference answers.
**It lives in `parse_set_point` and not in `compat/`, and that is load-bearing.** My first
attempt wrapped `SetPoint` per method table and `tests::region_map` caught it: the reference
registers it once in the Region method table, so every widget type runs the same function
object, and three wrapped copies broke an identity `region_map.rs` maintains on purpose (an
addon can pull `WorldFrame.GetHeight` off and apply it to a Texture). The header now says so,
so the wrapper route is not tried again.
Two tests pinned the old behaviour and are rewritten rather than deleted:
- The trailing-nil test gets **stronger**. It existed because `lua_type` tells `LUA_TNIL`
(the screen root, `0x7a2710`) from `LUA_TNONE`, and the ladder must see the count Lua saw.
Both forms resolve now, so it resolves a real layout and asserts they land in *different*
places: the explicit nil at the screen's corner, the absent one on its parent.
- One genuine ordering change, asserted: with no third argument there is no tag to gate, so
`SetPoint("MIDDLE")` reports "Unknown region point" where it reported `Usage:`. The
tag-gate-runs-first claim is kept for a *bad* tag, `SetPoint("MIDDLE", true)`.
Movement: Cinematic's load `CameraWheel.lua:243` → `MenuWheel.lua:312` (the secure-template
family, which `compat/classic_api/frame.rs` declines with its own reason).
benilla-ui 2077 passed, 0 failed. Full chain green.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SgstFWtn1RxEJ5kVrpgYwn
gromandClaude Opus 5
64f07d9864