error: C2039: 'pointer' : is not a member of 'QJsonObject::iterator'

Question

我在尝试将 'QJsonObject::iterator' 与 MSVC2013 一起使用时遇到奇怪的错误。

我有以下例子：

#include <QCoreApplication>
#include <QJsonObject>
#include <QDebug>
#include <algorithm>

void processValue(QJsonValue value) {
    qDebug() << value.toString();
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QJsonObject jsonObject;
    jsonObject.insert("a", "A");
    jsonObject.insert("b", "B");
    jsonObject.insert("c", "C");
    jsonObject.insert("d", "D");
    jsonObject.insert("e", "E");

    std::for_each (jsonObject.begin(), jsonObject.end(), processValue);

    return a.exec();
}

此代码在 MSVC2008（交叉编译为 WinCE）和 MinGW 中按预期编译和工作，但在 MSVC2013 中不正常。在所有情况下，我都使用 Qt 5.5.1。

错误信息是：

C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\xutility(375) : error C2039: 'pointer' : is not a member of 'QJsonObject::iterator'
        c:\qt\qt5.5.1msvc.5\msvc2013\include\qtcore\qjsonobject.h(96) : see declaration of 'QJsonObject::iterator'
        C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\xutility(584) : see reference to class template instantiation 'std::iterator_traits<_InIt>' being compiled
        with
        [
            _InIt=QJsonObject::iterator
        ]
        C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\algorithm(31) : see reference to function template instantiation 'void std::_Debug_range<_InIt>(_InIt,_InIt,std::_Dbfile_t,std::_Dbline_t)' being compiled
        with
        [
            _InIt=QJsonObject::iterator
        ]
        ..\QJsonObjectIteratorIssue\main.cpp(21) : see reference to function template instantiation '_Fn1 std::for_each<QJsonObject::iterator,void(__cdecl *)(QJsonValue)>(_InIt,_InIt,_Fn1)' being compiled
        with
        [
            _Fn1=void (__cdecl *)(QJsonValue)
,            _InIt=QJsonObject::iterator
        ]
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\xutility(375) : error C2146: syntax error : missing ';' before identifier 'pointer'
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\xutility(375) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\xutility(375) : error C2602: 'std::iterator_traits<_InIt>::pointer' is not a member of a base class of 'std::iterator_traits<_InIt>'
        with
        [
            _InIt=QJsonObject::iterator
        ]
        C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\xutility(375) : see declaration of 'std::iterator_traits<_InIt>::pointer'
        with
        [
            _InIt=QJsonObject::iterator
        ]
C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\INCLUDE\xutility(375) : error C2868: 'std::iterator_traits<_InIt>::pointer' : illegal syntax for using-declaration; expected qualified-name
        with
        [
            _InIt=QJsonObject::iterator
        ]

我是不是做错了什么，这只是碰巧在其他 2 个编译器上起作用？

Answer 1

使用 5.6 或向后移植：https://code.qt.io/cgit/qt/qtbase.git/commit/?id=4a318a61824216ac499ff8b0b0c55dea90501005

QJsonObject::(const_)iterator: add pointer typedef

Otherwise they're unusable with std::algorithms or anything else that requires iterator_traits.

error: C2039: 'pointer' : is not a member of 'QJsonObject::iterator'

error: C2039: 'pointer' : is not a member of 'QJsonObject::iterator'

c++

qt

std

qjsonobject

msvc12