Unable to use the library within a C++17 project

[ehorrent]

There is several compilation errors when trying to use the library within a C++17 project (I use the NuGet package and have no problem with std versions <= 14).
My version of VS2017 is 15.9.2.

Reproduction steps:
Create an empty console application, install Nuget Microsoft.Windows.ImplementationLibrary v1.0.190430.13 and just update your main to include wil/resources.h :

#include <windows.h>
#include <wil/resource.h>
int main()
{
}

Here are the error messages I get:

include\wil\wistd_type_traits.h(1011): error C2275: '_Tp': illegal use of this type as an expression
include\wil\wistd_type_traits.h(1010): note: see declaration of '_Tp'
include\wil\wistd_type_traits.h(1011): note: see reference to class template instantiation 'wistd::is_aggregate<_Tp>' being compiled
include\wil\wistd_type_traits.h(1011): error C3861: '__is_aggregate': identifier not found
include\wil\wistd_type_traits.h(1011): error C2975: '__v': invalid template argument for 'wistd::integral_constant', expected compile-time constant expression
include\wil\wistd_type_traits.h(113): note: see declaration of '__v'
include\wil\result_macros.h(2168): error C2440: '=': cannot convert from 'void (__cdecl *)(bool,const wil::FailureInfo &)' to 'void (__cdecl *)(bool,const wil::FailureInfo &) noexcept'
include\wil\result_macros.h(2168): note: Conversion to a function with more restrictive exception specification requires reinterpret_cast
include\wil\result_macros.h(2178): error C2440: '=': cannot convert from 'void (__cdecl *)(const wil::FailureInfo &)' to 'void (__cdecl *)(const wil::FailureInfo &) noexcept'
include\wil\result_macros.h(2178): note: Conversion to a function with more restrictive exception specification requires reinterpret_cast
include\wil\result_macros.h(2191): error C2440: '=': cannot convert from 'void (__cdecl *)(wil::FailureInfo *,PWSTR,::size_t)' to 'void (__cdecl *)(wil::FailureInfo *,PWSTR,::size_t) noexcept'
include\wil\result_macros.h(2191): note: Conversion to a function with more restrictive exception specification requires reinterpret_cast
include\wil\result_macros.h(2201): error C2440: '=': cannot convert from 'HRESULT (__cdecl *)(void)' to 'HRESULT (__cdecl *)(void) noexcept'
include\wil\result_macros.h(2201): note: Conversion to a function with more restrictive exception specification requires reinterpret_cast
include\wil\result_macros.h(2212): error C2440: '=': cannot convert from 'void (__cdecl *)(const wil::FailureInfo &)' to 'void (__cdecl *)(const wil::FailureInfo &) noexcept'
include\wil\result_macros.h(2212): note: Conversion to a function with more restrictive exception specification requires reinterpret_cast

Some messages seem related to this compiler issue: c++ compiler bug with decltype functions that have noexcept.

[dunhor]

Sounds like there's two issues here.

The first is that it seems like __is_aggregate is not available in some older versions of MSVC that support /std:c++17 (though this seems to suggest that it should be available in your version). The first is easily worked around by defining __WI_LIBCPP_HAS_NO_IS_AGGREGATE. We should ideally be conditionally defining this based off _MSC_VER or _MSC_FULL_VER, but sadly these things aren't well documented, so there's some amount of whack-a-mole that needs to get done.

The second is the bug that you link that seems to have been fixed in later versions. I've ironically had to add a workaround for function pointers for C++14 since behavior was broken in VS2019. This workaround can be leveraged to have WI_PFN_NOEXCEPT defined to nothing for earlier versions of MSVC.

I'd say feel free to submit a PR that conditionalizes the above on your MSVC version. If someone comes along with a later version of VS that's still broken, we'll have to bump the version numbers again, but I don't believe that there's any better option, unfortunately.

[icnocop]

As a work-around, downgrade the NuGet package Microsoft.Windows.ImplementationLibrary to 1.0.210803.1