fix some bugs in C module wrt metatables, wrap

src/taggedcoro.c

@@ -399,10 +399,6 @@ static int taggedcoro_cowrap (lua_State *L) {
       return luaL_error(L, "attempt to wrap an untagged coroutine");
     } else lua_pop(L, 1);
     lua_pushvalue(L, 1);
-    lua_createtable(L, 4, 0); /* meta = { <tag>, <stacked>, <parent>, <yielder> } */
-    lua_pushvalue(L, 1); /* copy tag to top */
-    lua_rawseti(L, -2, 1); /* meta[1] = tag */
-    lua_rawset(L, lua_upvalueindex(1)); /* coroset[co] = meta */
   } else taggedcoro_cocreate(L);
   lua_pushvalue(L, -1);
   lua_pushvalue(L, lua_upvalueindex(1));
@@ -641,8 +637,8 @@ static const luaL_Reg mt_funcs[] = {
 static int taggedcoro_install(lua_State *L) {
   lua_rawgeti(L, LUA_REGISTRYINDEX, LUA_RIDX_MAINTHREAD);
   lua_createtable(L, 0, 2);
-  lua_pushvalue(L, lua_upvalueindex(1)); /* extra metadada for each coroutine */
   luaL_newlibtable(L, mt_funcs); /* __index */
+  lua_pushvalue(L, lua_upvalueindex(1)); /* extra metadada for each coroutine */
   luaL_setfuncs(L, mt_funcs, 1);
   lua_setfield(L, -2, "__index");
   lua_pushcfunction(L, taggedcoro_cocall); /* __call */

src/taggedcoro.lua

@@ -111,7 +111,12 @@ function callk(co, meta, ok, ...)
     end
   elseif meta.tag ~= tag then
     if not isyieldable() then
-      return callk(co, meta, resume(co, MARK, "coroutine for tag " .. tostring(tag) .. " not found"))
+      local _, ismain = running()
+      if ismain then
+        return callk(co, meta, resume(co, MARK, "coroutine for tag " .. tostring(tag) .. " not found"))
+      else
+        return callk(co, meta, resume(co, MARK, "attempt to yield across a C-call boundary"))
+      end
     elseif coros[running()] then -- parent is tagged, pass it along
       meta.stacked = true
       return callkk(co, meta, pcall(yield, ...))

test/traceback.lua

@@ -201,6 +201,37 @@ do
   zero = oldzero
 end
 
+do
+  usetc = false
+  local oldzero, cozero = zero
+  zero, cozero = tc.wrap("zero", zero)
+  local ctwo = coroutine.wrap(two)
+  local ok, tb = xpcall(ctwo, function (msg)
+    return tc.traceback(msg, 1)
+  end)
+  assert(ok)
+  assert(tb == "zero")
+  zero = oldzero
+end
+
+do
+  local oldzero = zero
+  zero = function ()
+    tc.yield("two", "zero")
+  end
+  local cone = tc.wrap("one", one)
+  local ctwo = tc.wrap("two", function ()
+    return xpcall(function () assert(false) end, function (msg)
+      local ok, err = pcall(cone)
+      assert(not ok)
+      return err
+    end)
+  end)
+  local _, err = ctwo()
+  assert(err:match("attempt to yield"))
+  zero = oldzero
+end
+
 if _VERSION ~= "Lua 5.1" then
   tc = tc.install()