C++/CLI projects in Visual Studio

.NET 7 Preview 3 includes generic math APIs that use static abstract interface members on primitive types, such as Int32. Earlier versions of the C++/CLI compiler were incompatible with such members. Because those members are used on many primitive types, compilation errors will occur when targeting net7.0, even if you don't use the generic math features directly.

Beyond C++/CLI, it's also possible that the introduction of static abstract interface members on primitive System types will surface issues in other tools that aren't forward-compatible with the usage of this new language construct. If you're a tool author, you'll need to update any tools impacted by this change to accommodate the usage of static abstract interface members. If you need help, file an issue in the dotnet/runtime repo to request guidance.

Previous behavior

Previously, compiling .NET projects using C++/CLI did not result in errors related to members on primitive System types.

New behavior

Compiling a .NET 7 Preview 3 net7.0 project using C++/CLI in a release of Visual Studio version 17.2 prior to Preview 2 will result in many errors similar to this example:

error C2253: 'System.Int32.Parse': pure specifier or abstract override specifier only allowed on virtual function

Other than upgrading, there's no way to work around this compiler error. It's generated because of static abstract interface members on primitive System types. When you upgrade to Visual Studio 2022 version 17.2 Preview 2+, the compilation errors will no longer occur.

Implicitly implemented static abstract interface members can be invoked, but even with Visual Studio 2022 version 17.2 Preview 2+, C++/CLI doesn't support invoking explicitly implemented static abstract interface members.

Version introduced

.NET 7 Preview 3

Type of breaking change

This change can affect source compatibility.

Reason for change

.NET 7 Preview 3 includes the new API definitions for the generic math feature set. These APIs were introduced in .NET 6 as a preview feature and required you to install the System.Runtime.Experimental package to gain access. Starting in .NET 7 Preview 3, these generic math APIs are included "in box".

To continue using C++/CLI with .NET 7 Preview 3+, upgrade to Visual Studio 2022 version 17.2 Preview 2 or a later version.

Affected APIs

N/A

See also