Question

将VC ++项目从VS2010编译器升级到VS2015编译器并且我遇到了这个错误，我们将不胜感激。

C2475 'std::less<_Kty>::operator ()': redefinition; 'constexpr' specifier mismatch

这是产生错误的代码：

bool std::less < sp < ref::db::string > >::operator()( 
    const sp < ref::db::string >& first, 
    const sp < ref::db::string >& second ) const 
{
    return first->cpp() < second->cpp();
}

第二个示例错误：

'std::less<sp<ref::ifile>>::operator ()': redefinition; 'constexpr' specifier mismatch

代码：

template <>
bool std::less < sp < ref::ifile > >::operator()(
    const sp < ref::ifile >& x, 
    const sp < ref::ifile >& y ) const 
{
    if( std::tolower( x->name()->cpp() ) 
        == std::tolower( y->name()->cpp() ) )
    {
        return std::tolower( x->extention()->cpp() ) 
               < std::tolower( y->extention()->cpp() );
    }

    return std::tolower( x->name()->cpp() ) < std::tolower( y->name()->cpp() );
}

Answer 1

您是否尝试过将std::less<>类（仿函数）与operator()专门化的常用模式？

E.g：

namespace std 
{

template<>
struct less<sp<ref::db::string>> 
{
    bool operator()(const sp<ref::db::string>& first, 
                    const sp<ref::db::string>& second) const 
    {
        // Your custom std::less implementation code ...

        return first->cpp() < second->cpp();    
    }
};

} // namespace std

VC ++编译升级2010-＆gt; 2015重新定义; ＆＃39; constexpr＆＃39;说明符不匹配

1 个答案: