Re: copy ctor not called

[Travis Spencer <travislspencer at gmail dot com>]

On 7/2/05, Jeroen Wijnhout <Jeroen.Wijnhout@kdemail.net> wrote:
> Consider a class with a copy constructor:
> 
> class A
> {
> public:
>   A(int i) : m_i(i)
>   {
>     cout << "A(int i)" << endl;
>   }
> 
>   A(const A &a)
>   {
>     cout << "A(const A &a)" << endl;
>     m_i = a.i();

This doesn't compile:

copyctor.cpp: In copy constructor `A::A(const A&)':
copyctor.cpp:16: error: passing `const A' as `this' argument of `int A::i()'
   discards qualifiers

This does though:

    A(const A &a) : m_i(a.m_i)
    {
        cout << "A(const A &a)" << endl;
//        m_i = a.i();
    }

> Now, I understand that gcc optimizes away the copy constructor and interprets
> the code as:
> A a(2);
> 
> However, is there a way to force gcc to use the copy constructor?
> 

If I were a jerk, this is where I would say to RTFM, but since I'm not
I'll kindly point out the -fno-elide-constructors flag:

> CXXFLAGS=-fno-elide-constructors g++ -fno-elide-constructors  copyctor.cpp  -o copyctor
> ./copyctor
A(int i)
A(const A &a)

-- 

Regards,

Travis Spencer
Portland, OR USA