For historical reasons ILLinker assembly resolution logic was very explicit and done as a single step in the pipeline LoadReferencesStep this was easy to implement but it does not work well with the more advanced features which are have been and will keep be adding to the linker.

There are several drawbacks which would be addressed if the linker was able to resolve the assembly reference on demand during MarkStep (support for on-demand assembly resolution in any step is not required at this point) as well as potential speed improvement for loading and analyzing fewer assemblies. It'd also get ILLinker closer to csc behaviour and require only necessary references for processing to be specified and not all possible references as it's required today.

Related issues which would be addressed by this

• Reflection patterns can not resolve assemblies outside of the reference closure #943
• Embedded XML not processed for assemblies referenced only via PreserveDependency attribute #843
• [feature/dataflow] Add a pre-pass to scan type name strings in the app #1079