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Custom Marshalling Source Generation

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The ability to use source generation for P/Invokes was introduced in .NET 7. This also included a mechanism for custom marshalling of types.

This sample implements and uses custom marshallers for a built-in type and a user-defined type, including both stateless and stateful marshallers. It demonstrates the usage of attributes relevant to source generation for interop:

Prerequisites

Build and Run

  1. In order to build and run, all prerequisites must be installed. The following are also required:

    • On Linux/macOS, the C++ compiler (g++) must be on the path.
    • The C++ compiler (cl.exe or g++) and dotnet must be the same bitness (32-bit versus 64-bit).
      • On Windows, the sample is set up to use the bitness of dotnet to find the corresponding cl.exe

  2. Navigate to the root directory and run dotnet build

  3. Run the samples. Do one of the following:

    • Use dotnet run (which will build and run at the same time).
    • Use dotnet build to build the executable. The executable will be in bin under a subdirectory for the configuration (Debug is the default).
      • Windows: bin\Debug\custommarshalling.exe
      • Non-Windows: bin/Debug/custommarshalling

Note: The way the sample is built is relatively complicated. The goal is that it's possible to build and run the sample with a simple dotnet run command with minimal requirements for pre-installed tools. Typically, real-world projects that have both managed and native components will use different build systems for each; for example, msbuild/dotnet for managed and CMake for native.

Visual Studio support

The src\custommarshalling.sln can be used to open the sample in Visual Studio 2022. In order to be able to build from Visual Studio, though, it has to be started from the correct developer environment. From the developer environment console, start it with devenv src\custommarshalling.sln. With that, the solution can be built. To run it, set the start project to custommarshalling.