Strange behavior of copy-initialization, doesn't call the copy-constructor!

Question

I was reading the difference between direct-initialization and copy-initialization (§8.5/12):

T x(a);  //direct-initialization
T y = a; //copy-initialization         


        

Answer 1

This is an optimization by the compiler.

In evaluating: A a = 10; instead of:

1. first constructing a temporary object through A(int);

2. constructing a through the copy constructor and passing in the temporary;

the compiler will simply construct a using A(int).