Dear Devs,

Sorry if this is not the best place for reporting bugs.

I'm trying to use the lpeglabel library written in C and delivered as lpeglabel.so.

$ ls

testlabel.lua lpeglabel.so

$ cat testlabel.lua

require("lpeglabel")

The ConTeXt binary cannot load the library because it lacks certain Lua API:

$ context --forcecld --permitloadlib testlabel.lua

...

fatal lua error:
registered function call [1542]: ...tx/tex/texmf-context/tex/context/base/mkiv/l-package.lua:348: error loading module 'lpeglabel' from file './lpeglabel.so':
./lpeglabel.so: undefined symbol: lua_gettop

...

nor does LuaTeX:

$ luatex -luaonly testlabel.lua

error loading module 'lpeglabel' from file './lpeglabel.so':
./lpeglabel.so: undefined symbol: lua_getiuservalue

It seems that lua_gettop and others are optimized out from the `context` binary, while lua_getiuservalue and others are missing from `luatex`.

I'm not sure if it works but I would suggest adding `__attribute__ ((used))` to the `LUA_API` macro if the binaries are compiled with gcc.

Best,

Sylvain