Re: Non-inline special member functions?

From:
=?ISO-8859-1?Q?Daniel_Kr=FCgler?= <daniel.kruegler@googlemail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Wed, 6 Oct 2010 08:18:36 CST
Message-ID:
<6ae4285e-76c3-4c77-a7a4-1538296dafd6@k10g2000yqa.googlegroups.com>
On 6 Okt., 14:03, "Martin B." <0xCDCDC...@gmx.at> wrote:

While investigating some problems [1] with our code I noticed that the

standard

mandates (quoting from [2] N3126, section 12, p254 ff):

      [...] An implicitly-declared default constructor is an inline public

member

of its class.
      [...] An implicitly declared destructor is an inline public member

of its class.

      [...] An implicitly-declared copy[....] constructor is an inline

public

member of its class.

1) Does this actually mean that the compiler is required to inline the

ctor code?

No, an inline specifier is only considered as a non-binding request,
but it has consequences for an implementation nonetheless.

2) Is this over-specified? Why shouldn't an implementation be allowed to

put the

ctor code in a "real" function?


There is nothing that forbids that, but the effects must be the same.
A typical example is the following one:

#include <memory>

class SomeThing {
  class Impl; // Not defined here
  std::auto_ptr<Impl> pi;
} s;

This program is ill-formed and causes UB (depending on the
actual type Impl), because the inline destructor of SomeThing
will attempt to invoke delete on a pointer to Impl, which is
still an incomplete type at this point.

HTH & Greetings from Bremen,

Daniel Kr?gler

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