NativeAOT doesn't work with Linux non-portable build

[agocke]

The problem is that NativeAOT references OpenSSL in two different ways, depending on whether we're doing a portable build or not.

When portable, the Native AOT runtime uses lazy loading (dlopen) to load the installed OpenSSL shared library. This means that the final linking command for a Native AOT app doesn't need the OpenSSL dev shared library to be passed when linking, since it will not try to statically resolve symbols.

This is not true for non-portable builds. In this case, Native AOT is built directly against OpenSSL headers/SOs. This means that Native AOT apps have to pass the appropriate SO to the linker during final linking of NativeAOT apps.

This means that the linking of Native AOT apps depends on whether it was originally compiled with a portable build. We could also try to remove this difference at the root by choosing one way to reference OpenSSL consistently.

More broadly, the feature of a "non-portable" AOT build is questionable. This would produce a Native AOT compiler which can only compiler for the exact platform (e.g. Ubuntu 22.04) that the compiler was built for. This is generally an anti-pattern in compilers.

[omajid]

How does NativeAOT deal with bundled/system library split? source-build can be built so that it uses the system version of libunwind or the version included in runtime under src/native/external. Is that something else that needs to be tracked here?

[jkotas]

In source build, NativeAOT is built directly against OpenSSL headers/SOs. This means that NativeAOT apps have to pass the appropriate SO to the linker during final linking of NativeAOT apps.

All native dependencies are referenced directly in source build. We would need to do this for icu, gssapi, zlib, brotli, and potentially also libunwind that @omajid mentioned above.

[jkotas]

Not required for 7.0: dotnet/source-build#2885 (comment)

[crummel]

I've summarized what I believe to be the current state of play and the agreed-upon solution for NativeAOT in 7.0 in #76206. Please check this out and let me know if you have any concerns.