Currently, callers of add_swift_library provide a SHARED parameter (or specify IS_SDK_OVERLAY) to build a shared library, or provide nothing to build a static library. Various parts of the CMake build system then use the SWIFT_BUILD_STATIC_STDLIB global to determine whether to also build libraries marked as IS_SDK statically.

I think the initial change to make here is to instead require callers pass in SHARED or STATIC (or both) to add_swift_library. Ideally, SWIFT_BUILD_STATIC_STDLIB would only be used to determine whether calls to add_swift_library for the stdlib are passed STATIC.

I thought the only two options were STATIC or SHARED, but there's also MODULE and OBJECT_LIBRARY. Should add_swift_library take these as parameters as well? @gribozavr

We are using OBJECT_LIBRARY now, and not using MODULE.

First step: all callers now pass in STATIC, SHARED, or OBJECT_LIBRARY: #3020

I think the next step is to clean up add_swift_library a bit: instead of using IS_SDK, IS_SDK_OVERLAY and SWIFT_BUILD_STATIC_STDLIB, use only the STATIC and SHARED parameters to determine how to name the library targets:

• When only one of STATIC or SHARED is specified, the added target is target_name.

• When both STATIC and SHARED are specified, target_name and target_name-static are added.

As usual, feedback is welcome. Let me know if my approach seems off here.

I resolved this in #3027