CODEWITHSUNDEEP
c++new-operator
Alex
Alex

Reputation: 15333

No matching function for call to operator new

I'm trying to wrap a class from a library I'm using in Lua. Specifially, I'm trying to wrap the color class from SFML. The full source for the color class can be seen here and here.

This is the function that's that I'm failing in. 

int SFColor_new(lua_State* L)
{
    // omitting part where I set r, g, b, and a
    new (lua_newuserdata(L, sizeof(Color))) Color(r, g, b, a); // Line 47
    luaL_getmetatable(L, LuaInfo<Color>::myMetaTableName);
    lua_setmetatable(L, -2);
    return 1;
}

And this is the error

LuaSFMLColor.cpp: In function ‘int ag::SFColor_new(lua_State*)’:
LuaSFMLColor.cpp:47: error: no matching function for call to ‘operator new(unsigned int, void*)’
<built-in>:0: note: candidates are: void* operator new(unsigned int)
make: *** [game] Error 1

I do similar things in a few other places without running into this error, so I'm not sure what would be causing it. Looking at the Color's source code I don't see anything weird or out of the ordinary, and I've run out of ideas. I've also tried using the default constructor (i.e. no arguments) and then just setting the value afterward, but that didn't do any good either.

Upvotes: 46

Views: 22292

Answers (2)

michuu
michuu

Reputation: 325

The question has already been answered, but here's possible solution if you did #include <new> and still get error: no matching 'operator new' function for non-allocating placement new expression; include <new> on clang.
My code looked like this:

int* fun(const std::array<std::byte, 123>& param, std::size_t offset) {
    return new(param.data()+offset) int;
}

When I switched to GCC, I got error: invalid conversion from 'const void*' to 'void*, which is significantly more useful. param must be passed by non-const reference.
It might seem obvious, but the original code was much more complex and it was difficult to spot the actual source of the issue.

Upvotes: 2

CB Bailey
CB Bailey

Reputation: 792129

To use the standard placement form of new you have to #include <new>.

The form of new that you are using requires a declaration of void* operator new(std::size_t, void*) throw();.

You don't have to #include <new> to use non-placement new.

Upvotes: 117

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