```
for _, m in ipairs({'', 'k', 'kv', 'v'}) do
print('test', m)
a = {}; setmetatable(a, {__mode = m});
a[1], a[2], a[3] = {}, {}, {};
for k, v in pairs(a) do
print(k, v)
end
end
print('ok')
```
```
t = {}
t.__lt = function (a,b,c)
collectgarbage()
assert(c == nil)
if type(a) == 'table' then a = a.x end
if type(b) == 'table' then b = b.x end
return a<b, "dummy"
end
function Op(x) return setmetatable({x=x}, t) end
local function test ()
assert(not(Op(1)<Op(1)) and (Op(1)<Op(2)) and not(Op(2)<Op(1)))
assert(not(1 < Op(1)) and (Op(1) < 2) and not(2 < Op(1)))
assert(not(Op('a')<Op('a')) and (Op('a')<Op('b')) and not(Op('b')<Op('a')))
assert(not('a' < Op('a')) and (Op('a') < 'b') and not(Op('b') < Op('a')))
assert((Op(1)<=Op(1)) and (Op(1)<=Op(2)) and not(Op(2)<=Op(1)))
assert((Op('a')<=Op('a')) and (Op('a')<=Op('b')) and not(Op('b')<=Op('a')))
assert(not(Op(1)>Op(1)) and not(Op(1)>Op(2)) and (Op(2)>Op(1)))
assert(not(Op('a')>Op('a')) and not(Op('a')>Op('b')) and (Op('b')>Op('a')))
assert((Op(1)>=Op(1)) and not(Op(1)>=Op(2)) and (Op(2)>=Op(1)))
assert((1 >= Op(1)) and not(1 >= Op(2)) and (Op(2) >= 1))
assert((Op('a')>=Op('a')) and not(Op('a')>=Op('b')) and (Op('b')>=Op('a')))
assert(('a' >= Op('a')) and not(Op('a') >= 'b') and (Op('b') >= Op('a')))
end
test()
```
```
-- bug since 2.5 (C-stack overflow)
do
local function f (size)
local s = string.rep("a", size)
local p = string.rep(".?", size)
return pcall(string.match, s, p)
end
local r, m = f(80)
assert(r and #m == 80)
r, m = f(200000)
assert(not r and string.find(m, "too complex"), tostring(r)..", "..tostring(m))
end
```
```
do -- new (5.3.3) semantics for empty matches
assert(string.gsub("a b cd", " *", "-") == "-a-b-c-d-")
local res = ""
local sub = "a \nbc\t\td"
local i = 1
for p, e in string.gmatch(sub, "()%s*()") do
res = res .. string.sub(sub, i, p - 1) .. "-"
i = e
end
assert(res == "-a-b-c-d-")
end
```
