Compiler Error ASPIREEXPORT004

Version introduced: 13.2

Parameter '0' of type '1' in method '2' is not ATS-compatible. Use primitive types, enums, or supported Aspire types.

This diagnostic error is reported when a method decorated with [AspireExport] has a parameter whose type cannot be represented across language boundaries by the Aspire Type Specification (ATS). ATS-compatible parameter types include primitive types (such as string, int, bool, double), enums, and supported Aspire types such as IResourceBuilder<T>. Types that are not ATS-compatible include out parameters, open generic type parameters, params arrays, raw IResource instances, and arbitrary delegate types.

Example

The following code generates ASPIREEXPORT004:

C# — Integration.cs

[AspireExport("addRedis")]
public static IResourceBuilder<RedisResource> AddRedis(
    IResourceBuilder<IResourceWithEnvironment> builder,
    out string connectionString)  // 'out' parameters are not ATS-compatible
{
    connectionString = "...";
    return builder.WithReference(...);
}

To correct this error

Remove or replace the incompatible parameter type with an ATS-compatible type. Use primitive types, enums, or supported Aspire types:

C# — Integration.cs

[AspireExport("addRedis")]
public static IResourceBuilder<RedisResource> AddRedis(
    IResourceBuilder<IResourceWithEnvironment> builder,
    int port = 6379)
{
    return builder.WithReference(...);
}