A wrapper puts its own frame between the caller and the callee, which
silently changes the meaning of every stack-level-relative call.
`verb_prof::install` wraps every function in `_G`, and `_G` at that point
holds Lua's own stdlib as well as our bindings — so it wrapped `setfenv`.
pfUI's `api/api.lua:4` is `setfenv(1, pfUI:GetEnvironment())`, and level 1
from inside a wrapper is the wrapper, a C function, so Lua raises
``setfenv' cannot change environment of given object`.
One armed session logged **91** of those and lost pfUI, WhatsTraining_Turtle,
AI_VoiceOver, MasterTradeSkills, pfUI-addonskinner, pfUI-locplus and
PizzaSlices: an instrument that unloaded a third of the interface it was there
to measure, and whose numbers were therefore of a client without them.
`STACK_RELATIVE` names the four `wrap_table` must leave alone. `setfenv` and
`getfenv` take a level; `error(msg, level)` positions its message by one; and
`debugstack([start])` is the reference's traceback by level, which
`FuBarPlugin-2.0.lua:752` asks for as `debugstack(6, 1, 0)` and
`AceDB-2.0.lua:742` reads a specific line of. `pcall`/`xpcall` stay wrapped:
no level argument, and an armed session shows them working and worth seeing.
The test wraps `_G` and then runs pfUI's line, so it is the bug rather than a
restatement of the list; deleting the skip reproduces grom's exact error. The
module doc also claimed `_G` "holds our bindings and nothing else" at install
time, which is what made this easy to miss.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SgstFWtn1RxEJ5kVrpgYwn
gromandClaude Opus 5
7322a95a9d