It is MFC VC++ Visual Studio 2019 Community Update 16.11.2 under Win 10

My peoject is CMFCPROPERTY SHEET app.

For each property page Visual studio entered the constructor:

class CPgTraining : public CMFCPropertyPage
{
  DECLARE_DYNAMIC(CPgTraining)

public:
  CPgTraining::CPgTraining(): CMFCPropertyPage(CPgTraining::IDD)
 {
   m_psp.dwFlags &= ~PSP_HASHELP;
 }
 ..................................................

All is compiled just fine under ISO C++17.
But under ISO C++20 I am getting error:

1>PgNetData.cpp
1>D:\VS2019\StorageTmp\ANNet\ANNet\PgTraining.h(19,15): error C3254: 'CPgTraining': class contains explicit override '{ctor}' but does not derive from an interface that contains the function declaration
1>D:\VS2019\StorageTmp\ANNet\ANNet\PgTraining.h(19,28): error C3244: 'CPgTraining::CPgTraining(void)': this method was introduced by '<Unknown>' not by 'CMFCPropertyPage'
1>For every CMFCPropertyPage in the roject.

Removing initialization for base class is leading to exception.

How to correct it?

Try CPgTraining(): CMFCPropertyPage(CPgTraining::IDD) , that is, not repeating the class name twice when declaring the constructor. I'm not sure why it ever compiled, it doesn't look right.

Hi,

I agree with IgorTandetnik-1300, you should try to use the following code.

CPgTraining(): CMFCPropertyPage(CPgTraining::IDD)  

If you set Conformance Mode to /permissive-, the same error was also recovered under ISO C++17.

Best Regards,

Jeanine

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@George Yaroshevsky

May I know if you have got any chance to check my answer? I am glad to help if you have any other questions.

Thank you for replay. I get notification just now.

You are right: with /permission- error is under ISO C++ 17 also.

I previously was trying to understand /permissive- and /ZctwoPhase-
and copied code

include <iostream>

// zctwophase.cpp
// To test options, compile by using
// cl /EHsc /nologo /W4 zctwophase.cpp
// cl /EHsc /nologo /W4 /permissive- zctwophase.cpp
// cl /EHsc /nologo /W4 /permissive- /Zc:twoPhase- zctwophase.cpp

include <cstdio>

void func(long) { std::puts("Standard two-phase"); }
/
template<typename T> void g(T x)
{
func(0);
}

void func(int) { std::puts("Microsoft one-phase"); }

int main()
{
g(6174);
return 0;

}

from MS article about /ZctwoPhase- It supposed that under /permissive- it will display "Stndard...", and "Microsoft.. if added /ZctwoPhase- or removed/permissve-. I tryied it under L, ISO C++17 and clang platform and do not get right result.

Again, thank you fotr replay.

Yes, I check it. You are right. Thank you.