the error message of a lua function called with lua_pcall geting lost

I'm using lua 5.1 and I'm using lua to load functions that can then be called from C++.

int Error = luaL_loadfile(LuaState, "Test.lua");
if(!Error)
{
    Error = lua_pcall(LuaState, 0, LUA_MULTRET, 0);
}
if(Error)
{
    std::cerr << "-- " << lua_tostring(LuaState, -1) << std::endl;
    lua_pop(LuaState, 1);
}
else
{
    LuaStackBalancer LSB(LuaState); //Puts the Lua Stack back to the way it was found
    lua_pushstring(LuaState, "Run");
    lua_gettable(LuaState, LUA_GLOBALSINDEX);
    if(lua_isfunction(LuaState, -1))
    {
        if(lua_pcall(LuaState, 0, 0, 0))
        {
            std::cerr << "-- " << lua_tostring(LuaState, -1) << std::endl;
        }
    }
}

The problem is that if the lua function that I call from C++ calls another function that errors out then the return is the first argument of that function instead of the error message.

AlwaysErrorsOut defined as:

int AlwaysErrorsOut(lua_State *LuaState) 
{ 
    return luaL_error(LuaState, "Error Test Successful"); 
}

Lua Test 1:

--Test.lua
AlwaysErrorsOut("Weirdness is happening")

Out:

-- Test.lua:1: Error Test Successful

Lua Test 2:

--Test.lua
function Run()
    AlwaysErrorsOut("Weirdness is happening")
end

Out:

-- Weirdness is happening

开发者_运维技巧

My current theory is that after the error happens the error message is placed on top of the stack and the stack is then reduced to 1.

Anyone know how to prevent the loss of the error message?

---

The problem was with some bit of my code i had completely overlooked, in it i had another LuaStackBalancer object that was created and its destructor was called when the error was thrown resulting in the loss of the error message. ^^u

Thank you all for your help and please forgive my stupidity

---

Seems to work fine when completely converted to Lua (see below.) Perhaps the problem is that the lua_pcall is set for no return values. Try using LUA_MULTRET instead of 0 on the call to Run.

local x=loadstring[[
function AlwaysErrorsOut(s)
    error("Test Successfull")
end

function Run()
    AlwaysErrorsOut("Weirdness is happening")
end
]]

local a,b = pcall(x)

print(a) --> true
print(b) --> nil

local a,b = pcall(_G["Run"])

print(a) --> false
print(b) --> [string "function AlwaysErrorsOut(s)..."]:2: Test Successfull