Lifetime extension only works when a const reference is directly bound to a temporary. Temporaries returned from a function (even ones returned by const reference) are not eligible for lifetime extension. We show an example of this in lesson12.12 -- Return by reference and return by address....
根据该提案,现在可以更改在常量求值过程中创建的对象,直到求值过程或对象的 lifetime 结束。这些求值过程将在类似虚拟机的沙箱中进行,不会影响外部的代码。因此理论上,输出相同的 constexpr 参数将会输出相同的结果。 constexpr int f(int a){ int n = a; ++n; // ++n 不是一个常量表达式 return n * a;...
正确记录对象的 lifetime,访问未初始化的内存和已经析构的对象都是不允许的 当时还不允许在常量求值中把void*转换成T*,所以理所当然的 void* operator new(std::size_t); 不支持在常量求值中使用,取而代之的是 // new => initialize when allocate auto pa = new int(42); delete pa; // std::all...
Reference variables can be declared constexpr (their initializers have to bereference constant expressions): staticconstexprintconst&x=42;// constexpr reference to a const int object// (the object has static storage duration// due to life extension by a static reference) ...
Lifetime extension of the temporary created for reference binding. That’s the main issue here and it has little to do with brace initialization. The temporary usually has the same lifetime as the reference (https://eel.is/c++draft/class.temporary#6) and the problem is that the ...
PROPID_M_EXTENSION_LEN IShellFolderBand Media Control (Windows) Rebar Controls Reference ComboBoxEx Controls Overview Functions Sending and Retrieving Messages within a Transaction Transaction Types MSMQQueueInfo.Delete Public Format Names Developing for and Migrating Existing Code to Server Core (Window...
Question on the lifetime managment of objects at the lower levels #449 Json should not be constructible with 'json*' #448 Move value_t to namespace scope #447 Typo in README.md #446 make check compilation is unneccesarily slow #445 Problem in dump() in json.h caused by ss....
Specifying a Namespace Extension's Location Structures Structures Structures Structures Structures Rebar Control Reference Interfaces ISyncMgrConflictResolutionItems IRichEditOleCallback CompensationHandlerActivity.System.Workflow.ComponentModel.IActivityEventListener<System.Workflow.ComponentModel.ActivityExecutionStatusChang...
General Control Reference Constants Methods MSMQMessage.Body Macros Macros Button Controls IShellFolderViewDual3 Messages ServiceMetadataExtension.System.ServiceModel.IExtension<System.ServiceModel.ServiceHostBase>.Detach Method (System.ServiceModel.Description) IShellIconOverlay IParentAndItem Text Object Model Re...
PROPID_M_EXTENSION_LEN IShellFolderBand Media Control (Windows) Rebar Controls Reference ComboBoxEx Controls Overview Functions Sending and Retrieving Messages within a Transaction Transaction Types MSMQQueueInfo.Delete Public Format Names Developing for and Migrating Existing Code to Server Core (Windows)...