New functions 'lua_resetthread' and 'coroutine.kill'

New functions to reset/kill a thread/coroutine, mainly (only?) to
close any pending to-be-closed variable. ('lua_resetthread' also
allows a thread to be reused...)

testes/coroutine.lua

@@ -119,6 +119,51 @@ end
 assert(#a == 25 and a[#a] == 97)
 x, a = nil
 
+
+-- coroutine kill
+do
+  -- ok to kill a dead coroutine
+  local co = coroutine.create(print)
+  assert(coroutine.resume(co, "testing 'coroutine.kill'"))
+  assert(coroutine.status(co) == "dead")
+  assert(coroutine.kill(co))
+
+  -- cannot kill the running coroutine
+  local st, msg = pcall(coroutine.kill, coroutine.running())
+  assert(not st and string.find(msg, "running"))
+
+  local main = coroutine.running()
+
+  -- cannot kill a "normal" coroutine
+  ;(coroutine.wrap(function ()
+    local st, msg = pcall(coroutine.kill, main)
+    assert(not st and string.find(msg, "normal"))
+  end))()
+
+  -- to-be-closed variables in coroutines
+  local X
+  co = coroutine.create(function ()
+    local *toclose x = function (err) assert(err == nil); X = false end
+    X = true
+    coroutine.yield()
+  end)
+  coroutine.resume(co)
+  assert(X)
+  assert(coroutine.kill(co))
+  assert(not X and coroutine.status(co) == "dead")
+
+  -- error killing a coroutine
+  co = coroutine.create(function()
+    local *toclose x = function (err) assert(err == nil); error(111) end
+    coroutine.yield()
+  end)
+  coroutine.resume(co)
+  local st, msg = coroutine.kill(co)
+  assert(not st and coroutine.status(co) == "dead" and msg == 111)
+
+end
+
+
 -- yielding across C boundaries
 
 co = coroutine.wrap(function()

testes/main.lua

@@ -254,15 +254,15 @@ NoRun("error object is a table value", [[lua %s]], prog)
 
 
 -- chunk broken in many lines
-s = [=[ -- 
-function f ( x ) 
+s = [=[ --
+function f ( x )
   local a = [[
 xuxu
 ]]
   local b = "\
 xuxu\n"
   if x == 11 then return 1 + 12 , 2 + 20 end  --[[ test multiple returns ]]
-  return x + 1 
+  return x + 1
   --\\
 end
 return( f( 100 ) )
@@ -272,10 +272,10 @@ s = string.gsub(s, ' ', '\n\n')   -- change all spaces for newlines
 prepfile(s)
 RUN([[lua -e"_PROMPT='' _PROMPT2=''" -i < %s > %s]], prog, out)
 checkprogout("101\n13\t22\n\n")
-  
+
 prepfile[[#comment in 1st line without \n at the end]]
 RUN('lua %s', prog)
-  
+
 prepfile[[#test line number when file starts with comment line
 debug = require"debug"
 print(debug.getinfo(1).currentline)
@@ -306,6 +306,20 @@ NoRun("", "lua %s", prog)   -- no message
 prepfile("os.exit(false, true)")
 NoRun("", "lua %s", prog)   -- no message
 
+
+-- to-be-closed variables in main chunk
+prepfile[[
+  local *toclose x = function (err)
+    assert(err == 120)
+    print("Ok")
+  end
+  local *toclose e1 = function () error(120) end
+  os.exit(true, true)
+]]
+RUN('lua %s > %s', prog, out)
+checkprogout("Ok")
+
+
 -- remove temporary files
 assert(os.remove(prog))
 assert(os.remove(otherprog))