Re: reference lifetimes...

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 11 Nov 2009 00:55:01 -0800 (PST)
Message-ID:
<a7e8e609-16c8-48bf-8ef3-888ac787d20d@f16g2000yqm.googlegroups.com>
On Nov 10, 7:22 pm, "James" <n...@spam.invalid> wrote:

Here is my code:

#include <iostream>

struct foo
{
    foo()
    {
        std::cout << this
                  << "->foo::foo()"
                  << std::endl;
    }

    ~foo()
    {
        std::cout << this
                  << "->foo::~foo()"
                  << std::endl;
    }
};

struct foo_holder
{
    foo const& m_ref;
};

int main()
{
    {
        foo_holder fh = { foo() };
        std::cout << "okay" << std::endl;
    }

    std::cout << std::endl;

    {
        foo const& ref = foo();
        std::cout << "okay" << std::endl;
    }

    return 0;
}

Why does the const reference not properly maintain its
lifetime over the call to 'cout' when the reference is
contained within a POD 'foo_holder'?


Compiler bug?

I get the following output:

0x22ff50->foo::foo()
0x22ff50->foo::~foo()
okay

0x22ff50->foo::foo()
okay
0x22ff50->foo::~foo()

Something seems terribly wrong here... Is there anyway to
overcome this?


Use a different compiler? I get

    0012FF63->foo::foo()
    okay
    0012FF63->foo::~foo()

    0012FF5B->foo::foo()
    okay
    0012FF5B->foo::~foo()

using VC++. (G++ behaves as you describe, however. This looks
like a bug in g++.)

--
James Kanze

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