Runtimes: propagate SwiftRT objects via swiftCore

Runtime clients of swiftCore need the SwiftRT image-registration object on
their link lines. On COFF this object supplies pSwiftImageConstructor and
the .sw5* section range symbols used to register Swift metadata and
conformances for each image.

CMake propagates usage requirements when an OBJECT library appears in an
INTERFACE_LINK_LIBRARIES chain, but it does not add that object's payload
to the final consumer link line. Keep the swiftrt targets in the interface
for their usage requirements, and explicitly propagate their object files
with TARGET_OBJECTS.

Author: compnerd

Runtimes/Core/Core/CMakeLists.txt

@@ -353,16 +353,25 @@ target_link_libraries(swiftCore
     swiftRuntimeCoreCMakeConfig)
 
 string(TOLOWER "${SwiftCore_OBJECT_FORMAT}" SwiftCore_OBJECT_FORMAT_lc)
+# Runtime clients need the Swift image-registration object on their link lines
+# (on COFF this supplies pSwiftImageConstructor and the .sw5* section ranges).
+# CMake propagates usage requirements for an OBJECT library that appears in an
+# INTERFACE_LINK_LIBRARIES chain, but it does not also add the object's payload to
+# the final link line. Keep the swiftrt target for its usage requirements, and
+# explicitly propagate the object payload through swiftCore's interface.
 if("${SwiftCore_OBJECT_FORMAT_lc}" STREQUAL "elf")
   target_link_libraries(swiftCore INTERFACE
-    swiftrt)
+    swiftrt
+    $<TARGET_OBJECTS:swiftrt>)
 elseif("${SwiftCore_OBJECT_FORMAT_lc}" STREQUAL "coff")
   if(BUILD_SHARED_LIBS)
     target_link_libraries(swiftCore INTERFACE
-      swiftrt)
+      swiftrt
+      $<TARGET_OBJECTS:swiftrt>)
   else()
     target_link_libraries(swiftCore INTERFACE
-      swiftrtT)
+      swiftrtT
+      $<TARGET_OBJECTS:swiftrtT>)
   endif()
 endif()