Some tests are not running in CI on Appveyor (MSVC) about pfr

[apolukhin]

Yes, MSVC unfortunately works with structured bindings only. Other template metaprogramming tricks fail right now.

You can find the lines for explicitly disabling the tests here: https://github.com/apolukhin/magic_get/blob/6f35c872c88783a3e5da44f653ee22580472f208/test/Jamfile.v2#L18-L22

The situation may have changed since last time I was testing on MSVC. Right now I have no access to the latest MSVC. So if it is possible to enable some tests (probably with workarounding some issues) I'd be happy to merge the patches.

[apolukhin]

I've tried to reenable at least some of the MSVC test, but the compiler keeps crashing with the following message:

..\..\..\boost/pfr/detail/fields_count.hpp(95): fatal error C1001: Internal compiler error.
(compiler file 'd:\agent\_work\8\s\src\vctools\Compiler\CxxFE\sl\p1\cxx\parsetree\nodes.h', line 398)
 To work around this problem, try simplifying or changing the program near the locations listed above.
If possible please provide a repro here: https://developercommunity.visualstudio.com 
Please choose the Technical Support command on the Visual C++ 
 Help menu, or open the Technical Support help file for more information
    call "..\..\..\bin.v2\standalone\msvc\msvc-14.2\address-model-64\architecture-x86\msvc-setup.bat"  >nul

[apolukhin]

There's no more flat version in the library and the testing logic was rewritten.

Now MSVC runs more tests and I do enable more of those as soon as MSVC gets the required functionality