[SUGGESTION] Already constructed object getting constructed again as we pass it as out parameter ? why ?

[jituderaps]

AFAIK, the motive of out parameter is to accept an object(i.e. not constructed yet) and construct it, but what if we pass an already constructed object as out argument, it will get constructed / assigned again and that is inefficient.
for example :
demo of similar problem to understand the construction of object: https://cpp2.godbolt.org/z/zhYo997ad

fun: (out x: int) = x = 5;

main: () -> i32 = {
    v1: int = 9;
    // v2: int;
    
    fun(out v1);       // it should be illegal because it's inefficient (doesn't define the meaning of out parameter)
    // fun(out v2);      // works fine
}

Expected result : compilation error
Actual result/error : running fine

[JohelEGP]

That's like suggesting to ban v1 = 10 because v1 is already constructed.
= on an initialized variable already behaves like an out argument.
For more, see https://github.com/hsutter/cppfront/wiki/Cpp2:-operator=,-this-&-that#misc-notes.