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From "Travis Vitek (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (STDCXX-1055) some of the localization class declarations do not follow the ISO/IEC:14882:2003 specification
Date Mon, 06 Feb 2012 22:36:59 GMT

    [ https://issues.apache.org/jira/browse/STDCXX-1055?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13201710#comment-13201710
] 

Travis Vitek commented on STDCXX-1055:
--------------------------------------

{quote="Stefan Teleman"}
It is not true that money_base and time_base are not allowed to have virtual destructors.
The Standard specification does not provide any declaration for these classes' destructors
at all
{quote}

As you see from your snippet, the C++ Standard doesn't explicitly list them in the interface
and as far as I can tell, it doesn't require them. As mentioned previously, they are only
required in the derived facet classes (which get it from their other base {{std::locale::facet}}).

As you pointed out above, relying on these classes having behavior not required by the standard
_leads to writing very unportable code_. Example...

{code}

#include <locale>
#include <cassert>

bool virtual_destructor = false;

struct A : std::time_base
{
  /* virtual */ ~A() {
      virtual_destructor = true;
  }
};

int main ()
{
    std::time_base* p = new A;
    delete p;

    assert (virtual_destructor);
}
{code}

This code assumes that the destructor in the base is virtual. It is non-portable. It asserts
on gcc-4.3.4, gcc-4.4.5, sunpro-5.10 using stlport4 and the default standard library, as well
as acc-6.25. The test runs to completion (implying that the destructor is virtual) on msvc-11.0
and vacpp-11.1.

If you have some sort of conformance test that verifies the destructor of these bases is virtual,
I'm going to suggest that the conformance test is incorrect, or is at least verifying conformance
with the Dinkumware C++ Standard Library.
                
> some of the localization class declarations do not follow the ISO/IEC:14882:2003 specification
> ----------------------------------------------------------------------------------------------
>
>                 Key: STDCXX-1055
>                 URL: https://issues.apache.org/jira/browse/STDCXX-1055
>             Project: C++ Standard Library
>          Issue Type: Bug
>          Components: 22. Localization
>    Affects Versions: 4.2.1, 4.2.2, 4.2.x, 4.3.x, 5.0.0
>         Environment: Solaris 10 and 11, Linux (RedHat and OpenSUSE), Sun C++ Compiler
12.1, 12.2, 12.3, GCC4.
> The defect is independent of platform or compiler.
>            Reporter: Stefan Teleman
>              Labels: conformance, standards
>             Fix For: 4.2.x, 4.3.x, 5.0.0
>
>         Attachments: stdcxx-1055.patch
>
>
> For the following classes:
> std::codecvt<> and its specializations
> std::collate<> and its specializations
> std::ctype<> and its specializations
> std::ctype_byname<> and its specializations
> std::messages<> and its specializations
> std::messages_byname<> and its specializations
> std::money_get<> and its specializations
> std::moneypunct<> and is specializations
> std::moneypunct_byname<> and its specializations
> std::money_put<> and its specializations
> std::num_get<> and its specializations
> std::numpunct<> and its specializations
> std::numpunct_byname<> and its specializations
> std::num_put<> and its specializations
> std::time_get<> and its specializations
> std::time_get_byname<> and its specializations
> std::time_put<> and its specializations
> 1. all these type declarations must be of class type (and not of struct type)
> 2. all these classes must have protected virtual destructors
> 3. all the corresponding *_base (time_base, money_base, etc), must have virtual destructors
> The current implementation of these types as structs (with default public access
> specifier on their non-virtual destructors) causes failures in Perennial CPPVS V8.1.
> Changing the access specifier for these destructors requires some changes in the
> stdcxx tests for localization.
> Patch based on 4.2.1 to follow shortly.

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