Lua 5.3.5 ported to gitv5.3.5

This is the first commit for the branch Lua 5.3. All source files
were copied from the official distribution of 5.3.5 in the Lua site.
The test files are the same of 5.3.4. The manual came from the
previous RCS repository, revision 1.167.1.2.

1 files changed, 874 insertions, 0 deletions

diff --git a/testes/coroutine.lua b/testes/coroutine.lua
new file mode 100644
index 00000000..c8fc8572
--- /dev/null
+++ b/testes/coroutine.lua
@@ -0,0 +1,874 @@
+-- $Id: coroutine.lua,v 1.42 2016/11/07 13:03:20 roberto Exp $
+-- See Copyright Notice in file all.lua
+
+print "testing coroutines"
+
+local debug = require'debug'
+
+local f
+
+local main, ismain = coroutine.running()
+assert(type(main) == "thread" and ismain)
+assert(not coroutine.resume(main))
+assert(not coroutine.isyieldable())
+assert(not pcall(coroutine.yield))
+
+
+-- trivial errors
+assert(not pcall(coroutine.resume, 0))
+assert(not pcall(coroutine.status, 0))
+
+
+-- tests for multiple yield/resume arguments
+
+local function eqtab (t1, t2)
+  assert(#t1 == #t2)
+  for i = 1, #t1 do
+    local v = t1[i]
+    assert(t2[i] == v)
+  end
+end
+
+_G.x = nil   -- declare x
+function foo (a, ...)
+  local x, y = coroutine.running()
+  assert(x == f and y == false)
+  -- next call should not corrupt coroutine (but must fail,
+  -- as it attempts to resume the running coroutine)
+  assert(coroutine.resume(f) == false)
+  assert(coroutine.status(f) == "running")
+  local arg = {...}
+  assert(coroutine.isyieldable())
+  for i=1,#arg do
+    _G.x = {coroutine.yield(table.unpack(arg[i]))}
+  end
+  return table.unpack(a)
+end
+
+f = coroutine.create(foo)
+assert(type(f) == "thread" and coroutine.status(f) == "suspended")
+assert(string.find(tostring(f), "thread"))
+local s,a,b,c,d
+s,a,b,c,d = coroutine.resume(f, {1,2,3}, {}, {1}, {'a', 'b', 'c'})
+assert(s and a == nil and coroutine.status(f) == "suspended")
+s,a,b,c,d = coroutine.resume(f)
+eqtab(_G.x, {})
+assert(s and a == 1 and b == nil)
+s,a,b,c,d = coroutine.resume(f, 1, 2, 3)
+eqtab(_G.x, {1, 2, 3})
+assert(s and a == 'a' and b == 'b' and c == 'c' and d == nil)
+s,a,b,c,d = coroutine.resume(f, "xuxu")
+eqtab(_G.x, {"xuxu"})
+assert(s and a == 1 and b == 2 and c == 3 and d == nil)
+assert(coroutine.status(f) == "dead")
+s, a = coroutine.resume(f, "xuxu")
+assert(not s and string.find(a, "dead") and coroutine.status(f) == "dead")
+
+
+-- yields in tail calls
+local function foo (i) return coroutine.yield(i) end
+f = coroutine.wrap(function ()
+  for i=1,10 do
+    assert(foo(i) == _G.x)
+  end
+  return 'a'
+end)
+for i=1,10 do _G.x = i; assert(f(i) == i) end
+_G.x = 'xuxu'; assert(f('xuxu') == 'a')
+
+-- recursive
+function pf (n, i)
+  coroutine.yield(n)
+  pf(n*i, i+1)
+end
+
+f = coroutine.wrap(pf)
+local s=1
+for i=1,10 do
+  assert(f(1, 1) == s)
+  s = s*i
+end
+
+-- sieve
+function gen (n)
+  return coroutine.wrap(function ()
+    for i=2,n do coroutine.yield(i) end
+  end)
+end
+
+
+function filter (p, g)
+  return coroutine.wrap(function ()
+    while 1 do
+      local n = g()
+      if n == nil then return end
+      if math.fmod(n, p) ~= 0 then coroutine.yield(n) end
+    end
+  end)
+end
+
+local x = gen(100)
+local a = {}
+while 1 do
+  local n = x()
+  if n == nil then break end
+  table.insert(a, n)
+  x = filter(n, x)
+end
+
+assert(#a == 25 and a[#a] == 97)
+x, a = nil
+
+-- yielding across C boundaries
+
+co = coroutine.wrap(function()
+       assert(not pcall(table.sort,{1,2,3}, coroutine.yield))
+       assert(coroutine.isyieldable())
+       coroutine.yield(20)
+       return 30
+     end)
+
+assert(co() == 20)
+assert(co() == 30)
+
+
+local f = function (s, i) return coroutine.yield(i) end
+
+local f1 = coroutine.wrap(function ()
+             return xpcall(pcall, function (...) return ... end,
+               function ()
+                 local s = 0
+                 for i in f, nil, 1 do pcall(function () s = s + i end) end
+                 error({s})
+               end)
+           end)
+
+f1()
+for i = 1, 10 do assert(f1(i) == i) end
+local r1, r2, v = f1(nil)
+assert(r1 and not r2 and v[1] ==  (10 + 1)*10/2)
+
+
+function f (a, b) a = coroutine.yield(a);  error{a + b} end
+function g(x) return x[1]*2 end
+
+co = coroutine.wrap(function ()
+       coroutine.yield(xpcall(f, g, 10, 20))
+     end)
+
+assert(co() == 10)
+r, msg = co(100)
+assert(not r and msg == 240)
+
+
+-- unyieldable C call
+do
+  local function f (c)
+          assert(not coroutine.isyieldable())
+          return c .. c
+        end
+
+  local co = coroutine.wrap(function (c)
+               assert(coroutine.isyieldable())
+               local s = string.gsub("a", ".", f)
+               return s
+             end)
+  assert(co() == "aa")
+end
+
+
+-- errors in coroutines
+function foo ()
+  assert(debug.getinfo(1).currentline == debug.getinfo(foo).linedefined + 1)
+  assert(debug.getinfo(2).currentline == debug.getinfo(goo).linedefined)
+  coroutine.yield(3)
+  error(foo)
+end
+
+function goo() foo() end
+x = coroutine.wrap(goo)
+assert(x() == 3)
+local a,b = pcall(x)
+assert(not a and b == foo)
+
+x = coroutine.create(goo)
+a,b = coroutine.resume(x)
+assert(a and b == 3)
+a,b = coroutine.resume(x)
+assert(not a and b == foo and coroutine.status(x) == "dead")
+a,b = coroutine.resume(x)
+assert(not a and string.find(b, "dead") and coroutine.status(x) == "dead")
+
+
+-- co-routines x for loop
+function all (a, n, k)
+  if k == 0 then coroutine.yield(a)
+  else
+    for i=1,n do
+      a[k] = i
+      all(a, n, k-1)
+    end
+  end
+end
+
+local a = 0
+for t in coroutine.wrap(function () all({}, 5, 4) end) do
+  a = a+1
+end
+assert(a == 5^4)
+
+
+-- access to locals of collected corroutines
+local C = {}; setmetatable(C, {__mode = "kv"})
+local x = coroutine.wrap (function ()
+            local a = 10
+            local function f () a = a+10; return a end
+            while true do
+              a = a+1
+              coroutine.yield(f)
+            end
+          end)
+
+C[1] = x;
+
+local f = x()
+assert(f() == 21 and x()() == 32 and x() == f)
+x = nil
+collectgarbage()
+assert(C[1] == nil)
+assert(f() == 43 and f() == 53)
+
+
+-- old bug: attempt to resume itself
+
+function co_func (current_co)
+  assert(coroutine.running() == current_co)
+  assert(coroutine.resume(current_co) == false)
+  coroutine.yield(10, 20)
+  assert(coroutine.resume(current_co) == false)
+  coroutine.yield(23)
+  return 10
+end
+
+local co = coroutine.create(co_func)
+local a,b,c = coroutine.resume(co, co)
+assert(a == true and b == 10 and c == 20)
+a,b = coroutine.resume(co, co)
+assert(a == true and b == 23)
+a,b = coroutine.resume(co, co)
+assert(a == true and b == 10)
+assert(coroutine.resume(co, co) == false)
+assert(coroutine.resume(co, co) == false)
+
+
+-- other old bug when attempting to resume itself
+-- (trigger C-code assertions)
+do
+  local A = coroutine.running()
+  local B = coroutine.create(function() return coroutine.resume(A) end)
+  local st, res = coroutine.resume(B)
+  assert(st == true and res == false)
+
+  A = coroutine.wrap(function() return pcall(A, 1) end)
+  st, res = A()
+  assert(not st and string.find(res, "non%-suspended"))
+end
+
+
+-- attempt to resume 'normal' coroutine
+local co1, co2
+co1 = coroutine.create(function () return co2() end)
+co2 = coroutine.wrap(function ()
+        assert(coroutine.status(co1) == 'normal')
+        assert(not coroutine.resume(co1))
+        coroutine.yield(3)
+      end)
+
+a,b = coroutine.resume(co1)
+assert(a and b == 3)
+assert(coroutine.status(co1) == 'dead')
+
+-- infinite recursion of coroutines
+a = function(a) coroutine.wrap(a)(a) end
+assert(not pcall(a, a))
+a = nil
+
+
+-- access to locals of erroneous coroutines
+local x = coroutine.create (function ()
+            local a = 10
+            _G.f = function () a=a+1; return a end
+            error('x')
+          end)
+
+assert(not coroutine.resume(x))
+-- overwrite previous position of local `a'
+assert(not coroutine.resume(x, 1, 1, 1, 1, 1, 1, 1))
+assert(_G.f() == 11)
+assert(_G.f() == 12)
+
+
+if not T then
+  (Message or print)('\n >>> testC not active: skipping yield/hook tests <<<\n')
+else
+  print "testing yields inside hooks"
+
+  local turn
+  
+  function fact (t, x)
+    assert(turn == t)
+    if x == 0 then return 1
+    else return x*fact(t, x-1)
+    end
+  end
+
+  local A, B = 0, 0
+
+  local x = coroutine.create(function ()
+    T.sethook("yield 0", "", 2)
+    A = fact("A", 6)
+  end)
+
+  local y = coroutine.create(function ()
+    T.sethook("yield 0", "", 3)
+    B = fact("B", 7)
+  end)
+
+  while A==0 or B==0 do    -- A ~= 0 when 'x' finishes (similar for 'B','y')
+    if A==0 then turn = "A"; assert(T.resume(x)) end
+    if B==0 then turn = "B"; assert(T.resume(y)) end
+  end
+
+  assert(B // A == 7)    -- fact(7) // fact(6)
+
+  local line = debug.getinfo(1, "l").currentline + 2    -- get line number
+  local function foo ()
+    local x = 10    --<< this line is 'line'
+    x = x + 10
+    _G.XX = x
+  end
+
+  -- testing yields in line hook
+  local co = coroutine.wrap(function ()
+    T.sethook("setglobal X; yield 0", "l", 0); foo(); return 10 end)
+
+  _G.XX = nil;
+  _G.X = nil; co(); assert(_G.X == line)
+  _G.X = nil; co(); assert(_G.X == line + 1)
+  _G.X = nil; co(); assert(_G.X == line + 2 and _G.XX == nil)
+  _G.X = nil; co(); assert(_G.X == line + 3 and _G.XX == 20)
+  assert(co() == 10)
+
+  -- testing yields in count hook
+  co = coroutine.wrap(function ()
+    T.sethook("yield 0", "", 1); foo(); return 10 end)
+
+  _G.XX = nil;
+  local c = 0
+  repeat c = c + 1; local a = co() until a == 10
+  assert(_G.XX == 20 and c >= 5)
+
+  co = coroutine.wrap(function ()
+    T.sethook("yield 0", "", 2); foo(); return 10 end)
+
+  _G.XX = nil;
+  local c = 0
+  repeat c = c + 1; local a = co() until a == 10
+  assert(_G.XX == 20 and c >= 5)
+  _G.X = nil; _G.XX = nil
+
+  do
+    -- testing debug library on a coroutine suspended inside a hook
+    -- (bug in 5.2/5.3)
+    c = coroutine.create(function (a, ...)
+      T.sethook("yield 0", "l")   -- will yield on next two lines
+      assert(a == 10)
+      return ...
+    end)
+
+    assert(coroutine.resume(c, 1, 2, 3))   -- start coroutine
+    local n,v = debug.getlocal(c, 0, 1)    -- check its local
+    assert(n == "a" and v == 1)
+    n,v = debug.getlocal(c, 0, -1)         -- check varargs
+    assert(v == 2)
+    n,v = debug.getlocal(c, 0, -2)
+    assert(v == 3)
+    assert(debug.setlocal(c, 0, 1, 10))     -- test 'setlocal'
+    assert(debug.setlocal(c, 0, -2, 20))
+    local t = debug.getinfo(c, 0)        -- test 'getinfo'
+    assert(t.currentline == t.linedefined + 1)
+    assert(not debug.getinfo(c, 1))      -- no other level
+    assert(coroutine.resume(c))          -- run next line
+    v = {coroutine.resume(c)}         -- finish coroutine
+    assert(v[1] == true and v[2] == 2 and v[3] == 20 and v[4] == nil)
+    assert(not coroutine.resume(c))
+  end
+
+  do
+    -- testing debug library on last function in a suspended coroutine
+    -- (bug in 5.2/5.3)
+    local c = coroutine.create(function () T.testC("yield 1", 10, 20) end)
+    local a, b = coroutine.resume(c)
+    assert(a and b == 20)
+    assert(debug.getinfo(c, 0).linedefined == -1)
+    a, b = debug.getlocal(c, 0, 2)
+    assert(b == 10)
+  end
+
+
+  print "testing coroutine API"
+  
+  -- reusing a thread
+  assert(T.testC([[
+    newthread      # create thread
+    pushvalue 2    # push body
+    pushstring 'a a a'  # push argument
+    xmove 0 3 2   # move values to new thread
+    resume -1, 1    # call it first time
+    pushstatus
+    xmove 3 0 0   # move results back to stack
+    setglobal X    # result
+    setglobal Y    # status
+    pushvalue 2     # push body (to call it again)
+    pushstring 'b b b'
+    xmove 0 3 2
+    resume -1, 1    # call it again
+    pushstatus
+    xmove 3 0 0
+    return 1        # return result
+  ]], function (...) return ... end) == 'b b b')
+
+  assert(X == 'a a a' and Y == 'OK')
+
+
+  -- resuming running coroutine
+  C = coroutine.create(function ()
+        return T.testC([[
+                 pushnum 10;
+                 pushnum 20;
+                 resume -3 2;
+                 pushstatus
+                 gettop;
+                 return 3]], C)
+      end)
+  local a, b, c, d = coroutine.resume(C)
+  assert(a == true and string.find(b, "non%-suspended") and
+         c == "ERRRUN" and d == 4)
+
+  a, b, c, d = T.testC([[
+    rawgeti R 1    # get main thread
+    pushnum 10;
+    pushnum 20;
+    resume -3 2;
+    pushstatus
+    gettop;
+    return 4]])
+  assert(a == coroutine.running() and string.find(b, "non%-suspended") and
+         c == "ERRRUN" and d == 4)
+
+
+  -- using a main thread as a coroutine
+  local state = T.newstate()
+  T.loadlib(state)
+
+  assert(T.doremote(state, [[
+    coroutine = require'coroutine';
+    X = function (x) coroutine.yield(x, 'BB'); return 'CC' end;
+    return 'ok']]))
+
+  t = table.pack(T.testC(state, [[
+    rawgeti R 1     # get main thread
+    pushstring 'XX'
+    getglobal X    # get function for body
+    pushstring AA      # arg
+    resume 1 1      # 'resume' shadows previous stack!
+    gettop
+    setglobal T    # top
+    setglobal B    # second yielded value
+    setglobal A    # fist yielded value
+    rawgeti R 1     # get main thread
+    pushnum 5       # arg (noise)
+    resume 1 1      # after coroutine ends, previous stack is back
+    pushstatus
+    return *
+  ]]))
+  assert(t.n == 4 and t[2] == 'XX' and t[3] == 'CC' and t[4] == 'OK')
+  assert(T.doremote(state, "return T") == '2')
+  assert(T.doremote(state, "return A") == 'AA')
+  assert(T.doremote(state, "return B") == 'BB')
+
+  T.closestate(state)
+
+  print'+'
+
+end
+
+
+-- leaving a pending coroutine open
+_X = coroutine.wrap(function ()
+      local a = 10
+      local x = function () a = a+1 end
+      coroutine.yield()
+    end)
+
+_X()
+
+
+if not _soft then
+  -- bug (stack overflow)
+  local j = 2^9
+  local lim = 1000000    -- (C stack limit; assume 32-bit machine)
+  local t = {lim - 10, lim - 5, lim - 1, lim, lim + 1}
+  for i = 1, #t do
+    local j = t[i]
+    co = coroutine.create(function()
+           local t = {}
+           for i = 1, j do t[i] = i end
+           return table.unpack(t)
+         end)
+    local r, msg = coroutine.resume(co)
+    assert(not r)
+  end
+  co = nil
+end
+
+
+assert(coroutine.running() == main)
+
+print"+"
+
+
+print"testing yields inside metamethods"
+
+local mt = {
+  __eq = function(a,b) coroutine.yield(nil, "eq"); return a.x == b.x end,
+  __lt = function(a,b) coroutine.yield(nil, "lt"); return a.x < b.x end,
+  __le = function(a,b) coroutine.yield(nil, "le"); return a - b <= 0 end,
+  __add = function(a,b) coroutine.yield(nil, "add"); return a.x + b.x end,
+  __sub = function(a,b) coroutine.yield(nil, "sub"); return a.x - b.x end,
+  __mod = function(a,b) coroutine.yield(nil, "mod"); return a.x % b.x end,
+  __unm = function(a,b) coroutine.yield(nil, "unm"); return -a.x end,
+  __bnot = function(a,b) coroutine.yield(nil, "bnot"); return ~a.x end,
+  __shl = function(a,b) coroutine.yield(nil, "shl"); return a.x << b.x end,
+  __shr = function(a,b) coroutine.yield(nil, "shr"); return a.x >> b.x end,
+  __band = function(a,b)
+             a = type(a) == "table" and a.x or a
+             b = type(b) == "table" and b.x or b
+             coroutine.yield(nil, "band")
+             return a & b
+           end,
+  __bor = function(a,b) coroutine.yield(nil, "bor"); return a.x | b.x end,
+  __bxor = function(a,b) coroutine.yield(nil, "bxor"); return a.x ~ b.x end,
+
+  __concat = function(a,b)
+               coroutine.yield(nil, "concat");
+               a = type(a) == "table" and a.x or a
+               b = type(b) == "table" and b.x or b
+               return a .. b
+             end,
+  __index = function (t,k) coroutine.yield(nil, "idx"); return t.k[k] end,
+  __newindex = function (t,k,v) coroutine.yield(nil, "nidx"); t.k[k] = v end,
+}
+
+
+local function new (x)
+  return setmetatable({x = x, k = {}}, mt)
+end
+
+
+local a = new(10)
+local b = new(12)
+local c = new"hello"
+
+local function run (f, t)
+  local i = 1
+  local c = coroutine.wrap(f)
+  while true do
+    local res, stat = c()
+    if res then assert(t[i] == nil); return res, t end
+    assert(stat == t[i])
+    i = i + 1
+  end
+end
+
+
+assert(run(function () if (a>=b) then return '>=' else return '<' end end,
+       {"le", "sub"}) == "<")
+-- '<=' using '<'
+mt.__le = nil
+assert(run(function () if (a<=b) then return '<=' else return '>' end end,
+       {"lt"}) == "<=")
+assert(run(function () if (a==b) then return '==' else return '~=' end end,
+       {"eq"}) == "~=")
+
+assert(run(function () return a & b + a end, {"add", "band"}) == 2)
+
+assert(run(function () return a % b end, {"mod"}) == 10)
+
+assert(run(function () return ~a & b end, {"bnot", "band"}) == ~10 & 12)
+assert(run(function () return a | b end, {"bor"}) == 10 | 12)
+assert(run(function () return a ~ b end, {"bxor"}) == 10 ~ 12)
+assert(run(function () return a << b end, {"shl"}) == 10 << 12)
+assert(run(function () return a >> b end, {"shr"}) == 10 >> 12)
+
+assert(run(function () return a..b end, {"concat"}) == "1012")
+
+assert(run(function() return a .. b .. c .. a end,
+       {"concat", "concat", "concat"}) == "1012hello10")
+
+assert(run(function() return "a" .. "b" .. a .. "c" .. c .. b .. "x" end,
+       {"concat", "concat", "concat"}) == "ab10chello12x")
+
+
+do   -- a few more tests for comparsion operators
+  local mt1 = {
+    __le = function (a,b)
+      coroutine.yield(10)
+      return
+        (type(a) == "table" and a.x or a) <= (type(b) == "table" and b.x or b)
+    end,
+    __lt = function (a,b)
+      coroutine.yield(10)
+      return
+        (type(a) == "table" and a.x or a) < (type(b) == "table" and b.x or b)
+    end,
+  }
+  local mt2 = { __lt = mt1.__lt }   -- no __le
+
+  local function run (f)
+    local co = coroutine.wrap(f)
+    local res
+    repeat
+      res = co()
+    until res ~= 10
+    return res
+  end
+  
+  local function test ()
+    local a1 = setmetatable({x=1}, mt1)
+    local a2 = setmetatable({x=2}, mt2)
+    assert(a1 < a2)
+    assert(a1 <= a2)
+    assert(1 < a2)
+    assert(1 <= a2)
+    assert(2 > a1)
+    assert(2 >= a2)
+    return true
+  end
+  
+  run(test)
+
+end
+
+assert(run(function ()
+             a.BB = print
+             return a.BB
+           end, {"nidx", "idx"}) == print)
+
+-- getuptable & setuptable
+do local _ENV = _ENV
+  f = function () AAA = BBB + 1; return AAA end
+end
+g = new(10); g.k.BBB = 10;
+debug.setupvalue(f, 1, g)
+assert(run(f, {"idx", "nidx", "idx"}) == 11)
+assert(g.k.AAA == 11)
+
+print"+"
+
+print"testing yields inside 'for' iterators"
+
+local f = function (s, i)
+      if i%2 == 0 then coroutine.yield(nil, "for") end
+      if i < s then return i + 1 end
+    end
+
+assert(run(function ()
+             local s = 0
+             for i in f, 4, 0 do s = s + i end
+             return s
+           end, {"for", "for", "for"}) == 10)
+
+
+
+-- tests for coroutine API
+if T==nil then
+  (Message or print)('\n >>> testC not active: skipping coroutine API tests <<<\n')
+  return
+end
+
+print('testing coroutine API')
+
+local function apico (...)
+  local x = {...}
+  return coroutine.wrap(function ()
+    return T.testC(table.unpack(x))
+  end)
+end
+
+local a = {apico(
+[[
+  pushstring errorcode
+  pcallk 1 0 2;
+  invalid command (should not arrive here)
+]],
+[[return *]],
+"stackmark",
+error
+)()}
+assert(#a == 4 and
+       a[3] == "stackmark" and
+       a[4] == "errorcode" and
+       _G.status == "ERRRUN" and
+       _G.ctx == 2)       -- 'ctx' to pcallk
+
+local co = apico(
+  "pushvalue 2; pushnum 10; pcallk 1 2 3; invalid command;",
+  coroutine.yield,
+  "getglobal status; getglobal ctx; pushvalue 2; pushstring a; pcallk 1 0 4; invalid command",
+  "getglobal status; getglobal ctx; return *")
+
+assert(co() == 10)
+assert(co(20, 30) == 'a')
+a = {co()}
+assert(#a == 10 and
+       a[2] == coroutine.yield and
+       a[5] == 20 and a[6] == 30 and
+       a[7] == "YIELD" and a[8] == 3 and
+       a[9] == "YIELD" and a[10] == 4)
+assert(not pcall(co))   -- coroutine is dead now
+
+
+f = T.makeCfunc("pushnum 3; pushnum 5; yield 1;")
+co = coroutine.wrap(function ()
+  assert(f() == 23); assert(f() == 23); return 10
+end)
+assert(co(23,16) == 5)
+assert(co(23,16) == 5)
+assert(co(23,16) == 10)
+
+
+-- testing coroutines with C bodies
+f = T.makeCfunc([[
+        pushnum 102
+        yieldk  1 U2
+        cannot be here!
+]],
+[[      # continuation
+        pushvalue U3   # accessing upvalues inside a continuation
+        pushvalue U4
+        return *
+]], 23, "huu")
+
+x = coroutine.wrap(f)
+assert(x() == 102)
+eqtab({x()}, {23, "huu"})
+
+
+f = T.makeCfunc[[pushstring 'a'; pushnum 102; yield 2; ]]
+
+a, b, c, d = T.testC([[newthread; pushvalue 2; xmove 0 3 1; resume 3 0;
+                       pushstatus; xmove 3 0 0;  resume 3 0; pushstatus;
+                       return 4; ]], f)
+
+assert(a == 'YIELD' and b == 'a' and c == 102 and d == 'OK')
+
+
+-- testing chain of suspendable C calls
+
+local count = 3   -- number of levels
+
+f = T.makeCfunc([[
+  remove 1;             # remove argument
+  pushvalue U3;         # get selection function
+  call 0 1;             # call it  (result is 'f' or 'yield')
+  pushstring hello      # single argument for selected function
+  pushupvalueindex 2;   # index of continuation program
+  callk 1 -1 .;         # call selected function
+  errorerror            # should never arrive here
+]],
+[[
+  # continuation program
+  pushnum 34    # return value
+  return *     # return all results
+]],
+function ()     -- selection function
+  count = count - 1
+  if count == 0 then return coroutine.yield
+  else return f
+  end
+end
+)
+
+co = coroutine.wrap(function () return f(nil) end)
+assert(co() == "hello")   -- argument to 'yield'
+a = {co()}
+-- three '34's (one from each pending C call)
+assert(#a == 3 and a[1] == a[2] and a[2] == a[3] and a[3] == 34)
+
+
+-- testing yields with continuations
+
+co = coroutine.wrap(function (...) return
+       T.testC([[ # initial function
+          yieldk 1 2
+          cannot be here!
+       ]],
+       [[  # 1st continuation
+         yieldk 0 3 
+         cannot be here!
+       ]],
+       [[  # 2nd continuation
+         yieldk 0 4 
+         cannot be here!
+       ]],
+       [[  # 3th continuation
+          pushvalue 6   # function which is last arg. to 'testC' here
+          pushnum 10; pushnum 20;
+          pcall 2 0 0   # call should throw an error and return to next line
+          pop 1         # remove error message
+          pushvalue 6
+          getglobal status; getglobal ctx
+          pcallk 2 2 5  # call should throw an error and jump to continuation
+          cannot be here!
+       ]],
+       [[  # 4th (and last) continuation
+         return *
+       ]],
+       -- function called by 3th continuation
+       function (a,b) x=a; y=b; error("errmsg") end,
+       ...
+)
+end)
+
+local a = {co(3,4,6)}
+assert(a[1] == 6 and a[2] == nil)
+a = {co()}; assert(a[1] == nil and _G.status == "YIELD" and _G.ctx == 2)
+a = {co()}; assert(a[1] == nil and _G.status == "YIELD" and _G.ctx == 3)
+a = {co(7,8)};
+-- original arguments
+assert(type(a[1]) == 'string' and type(a[2]) == 'string' and
+     type(a[3]) == 'string' and type(a[4]) == 'string' and
+     type(a[5]) == 'string' and type(a[6]) == 'function')
+-- arguments left from fist resume
+assert(a[7] == 3 and a[8] == 4)
+-- arguments to last resume
+assert(a[9] == 7 and a[10] == 8)
+-- error message and nothing more
+assert(a[11]:find("errmsg") and #a == 11)
+-- check arguments to pcallk
+assert(x == "YIELD" and y == 4)
+
+assert(not pcall(co))   -- coroutine should be dead
+
+
+-- bug in nCcalls
+local co = coroutine.wrap(function ()
+  local a = {pcall(pcall,pcall,pcall,pcall,pcall,pcall,pcall,error,"hi")}
+  return pcall(assert, table.unpack(a))
+end)
+
+local a = {co()}
+assert(a[10] == "hi")
+
+print'OK'