-- Builtins that require an argument (luaL_checkany etc.) must raise on zero
-- args, not silently return nil or trap. Audit-found via a zero-arg sweep.
local function probe(name, fn) local ok, e = pcall(fn); print(name, ok, ok and "-" or type(e)) end
probe("tostring", tostring)
probe("tonumber", tonumber)
probe("rawequal", rawequal)
probe("getmetatable", getmetatable)
probe("ipairs", ipairs)
probe("pairs", pairs)
probe("math.type", math.type)
probe("math.tointeger", math.tointeger)
probe("math.max", math.max)
probe("math.min", math.min)
probe("string.pack", string.pack)
probe("string.unpack", string.unpack)
probe("string.packsize", string.packsize)
-- controls that are already correct (must not regress)
probe("string.char", string.char)
probe("type", type)
probe("math.floor", math.floor)
probe("string.len", string.len)
-- positive controls: valid args still work
print("tostring(5)", tostring(5))
print("math.max(3,7)", math.max(3, 7))
print("rawequal(1,1)", rawequal(1, 1))
print("getmetatable('x')", type(getmetatable("x")))