[Breaking change]: Mono embedding APIs no longer supported on mobile platforms #56482

Description

Mono embedding APIs no longer supported on mobile platforms

Version

.NET 11

Previous behavior

Native code could embed Mono by using Mono header files, linking to
libmonosgen-2.0, and calling mono_* APIs. These APIs exposed runtime,
domain, metadata, object, method-call, GC-handle, internal-call, thread, and
profiling features.

New behavior

Mono embedding APIs are no longer supported. CoreCLR on mobile platforms
doesn't provide a direct replacement for the Mono embedding API.

This change doesn't affect normal P/Invoke, LibraryImport, Java interop, or
Objective-C interop.

Type of breaking change

• Source incompatible
• Binary incompatible
• Behavioral change

Reason for change

Mono and CoreCLR use different hosting and embedding interfaces.

Recommended action

• Follow
  native interoperability best practices.
• Use [UnmanagedCallersOnly] and C# function pointers for native-to-managed
  callbacks.
• Use values that have the same layout in managed and native code (blittable
  values).
• Consider moving performance-critical, chatty managed/native interfaces to a
  fully managed implementation to reduce interop overhead.

Feature area

Interop

Affected APIs

The Mono native embedding API, including mono_* functions and
libmonosgen-2.0.

@rolfbjarne @jonathanpeppers @jkotas @steveisok

Associated WorkItem - 640005