Native AOT: Microsoft.Extensions.DependencyInjection

[weifenluo]

Is Microsoft.Extensions.DependencyInjection native AOT compatible? I assume it uses reflection for DI intensively, and I can't seem to find a source generator mode like provided by System.Text.Json.

I'm asking this question because I'm evaluating whether I should build my library on top of it without losing native AOT compatibility.

[davidfowl]

Yea, it's AOT compatible, there's no source generator for it. See #91675 (comment) for more details.

[weifenluo]

@davidfowl Thanks for your reply, it's very informative!

I still don't understand how Microsoft.Extensions.DependencyInjection can be AOT compatible without any source generator. Given the following EF Core DbContext constructor:

public class MyDbContext(DbContextOptions<MyDbContext> options) : DbContext
    : base(options)
{
    ...
}

There is nowhere else calling this constructor except DI via reflection. How can we prevent this constructor from being trimmed?

[davidfowl]

MEDI uses annotations to root services registered. Methods like AddDbContext are annotated with the right set of attributes to let the trimmer know what to keep when using DI.

Read more about it here https://learn.microsoft.com/en-us/dotnet/core/deploying/trimming/prepare-libraries-for-trimming
Watch the video here https://youtu.be/N-MrQeZ1enY?si=g3Fv2HLdKmtlUTVD

PS: If you don't get AOT warnings when you compile, then it should work just fine at runtime.