build: avoid rpath, library search path handling

Create an imported library target for the runtime libraries rather than
add the explicit library search path handling.  This avoids the need for
the rpath in the tests, and allows cmake to properly model dependencies.
It also makes the build system more amenable to
cross-compiling/cross-linking by avoiding ELF linker specific options.

Author: compnerd

tests/CMakeLists.txt

@@ -2,6 +2,19 @@
 execute_process(COMMAND "${CMAKE_COMMAND}" -E create_symlink "${CMAKE_SOURCE_DIR}/private" "${CMAKE_CURRENT_BINARY_DIR}/dispatch")
 execute_process(COMMAND "${CMAKE_COMMAND}" -E create_symlink "${CMAKE_CURRENT_SOURCE_DIR}/leaks-wrapper.sh" "${CMAKE_CURRENT_BINARY_DIR}/leaks-wrapper")
 
+# TODO(compnerd) hoist this out of the test directory
+if(SWIFT_RUNTIME_LIBDIR)
+  add_library(swiftCore SHARED IMPORTED)
+  set_target_properties(swiftCore
+                        PROPERTIES
+                          IMPORTED_LOCATION ${SWIFT_RUNTIME_LIBDIR}/${CMAKE_SHARED_LIBRARY_PREFIX}swiftCore${CMAKE_SHARED_LIBRARY_SUFFIX})
+
+  add_library(swiftSwiftOnoneSupport SHARED IMPORTED)
+  set_target_properties(swiftSwiftOnoneSupport
+                        PROPERTIES
+                          IMPORTED_LOCATION ${SWIFT_RUNTIME_LIBDIR}/${CMAKE_SHARED_LIBRARY_PREFIX}swiftSwiftOnoneSupport${CMAKE_SHARED_LIBRARY_SUFFIX})
+endif()
+
 add_library(bsdtests
             STATIC
               bsdtests.c
@@ -38,12 +51,11 @@ if(BSD_OVERLAY_FOUND)
                         PRIVATE
                           ${BSD_OVERLAY_LDFLAGS})
 endif()
-
-if(CMAKE_SWIFT_RUNTIME_LIBDIR)
+if(ENABLE_SWIFT)
   target_link_libraries(bsdtestharness
                         PRIVATE
-                        -L${CMAKE_SWIFT_RUNTIME_LIBDIR} -lswiftCore -lswiftSwiftOnoneSupport
-                        -Wl,-rpath -Wl,${CMAKE_SWIFT_RUNTIME_LIBDIR})
+                          swiftCore
+                          swiftSwiftOnoneSupport)
 endif()
 
 function(add_unit_test name)
@@ -84,11 +96,11 @@ function(add_unit_test name)
                           PRIVATE
                             ${BSD_OVERLAY_LDFLAGS})
   endif()
-  if(CMAKE_SWIFT_RUNTIME_LIBDIR)
+  if(ENABLE_SWIFT)
     target_link_libraries(${name}
                           PRIVATE
-                          -L${CMAKE_SWIFT_RUNTIME_LIBDIR} -lswiftCore -lswiftSwiftOnoneSupport
-                          -Wl,-rpath -Wl,${CMAKE_SWIFT_RUNTIME_LIBDIR})
+                            swiftCore
+                            swiftSwiftOnoneSupport)
   endif()
   target_link_libraries(${name} PRIVATE bsdtests)
   add_test(NAME ${name}