AssemblyBuilder.Save in .NET 8

[ShalokShalom]

Prototype: https://github.com/dotnet/runtimelab/tree/feature/assembly-builder-save

Issue: dotnet/runtime#15704 (comment)

Hint: Once this is implemented, change the Readme accordingly

[RyanLamansky]

If this ships I will definitely plug it in 👍

[Terricide]

Looks like it is in .net 9.0 preview

[RyanLamansky]

If it's still there when .NET 9 releases, I'll integrate it!

[RyanLamansky]

.NET 9 seems to have shipped with a way to save assemblies. I haven't tried it yet, but the API looks like what we need.

Some work is required to integrate it. In particular, the compiler assumes that the user will figure out how to supply all the imports and accept the exports, but when saving a DLL, people will expect to have generated types to cover both sides of that. So, the beginning and end of the compilation process will need some updates. I'll work on this when I have time, but PRs are always welcome 😇

[RyanLamansky]

Status update: I just committed partial work to c2beb13. It's not generating the import/export classes correctly yet but it's able to convert the main body of WASM code to a .NET DLL now. Fun fact: in the early days of this project, I mainly built on .NET Framework 4.x which had AssemblyBuilder.Save functionality which was extremely useful to figure out all the ways I was generating IL incorrectly. It's really nice to have that capability again.

It would be neat it someone pointed .NET DLL "decompiler" to a converted WASM DLL to see what it could do. In theory this could enable a C-or-Rust to C# conversion, for example, but there are many things raw WASM/IL can do that C# can't so I'm sure it would struggle.

Anyway, just wanted to share a progress update. I'm not sure how long it'll take me to get the last issues sorted out but I intend to do a new full release (it'd be version 1.3) once it seems to be working and I'm happy with the API.