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Message-ID: <e3b7bac05070212174b4df2fb@mail.gmail.com>
Date: Sat, 02 Jul 2005 19:17:00 -0000
From: Travis Spencer <travislspencer@gmail.com>
Reply-To: Travis Spencer <travislspencer@gmail.com>
To: Jeroen Wijnhout <Jeroen.Wijnhout@kdemail.net>
Subject: Re: copy ctor not called
Cc: gcc-help@gcc.gnu.org
In-Reply-To: <200507022024.10598.Jeroen.Wijnhout@kdemail.net>
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References: <200507022024.10598.Jeroen.Wijnhout@kdemail.net>
X-SW-Source: 2005-07/txt/msg00017.txt.bz2

On 7/2/05, Jeroen Wijnhout <Jeroen.Wijnhout@kdemail.net> wrote:
> Consider a class with a copy constructor:
>=20
> class A
> {
> public:
>   A(int i) : m_i(i)
>   {
>     cout << "A(int i)" << endl;
>   }
>=20
>   A(const A &a)
>   {
>     cout << "A(const A &a)" << endl;
>     m_i =3D 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 =3D a.i();
    }

> Now, I understand that gcc optimizes away the copy constructor and interp=
rets
> the code as:
> A a(2);
>=20
> However, is there a way to force gcc to use the copy constructor?
>=20

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=3D-fno-elide-constructors g++ -fno-elide-constructors  copyctor.=
cpp  -o copyctor
> ./copyctor
A(int i)
A(const A &a)

--=20

Regards,

Travis Spencer
Portland, OR USA