fix RPATH

Author: rintaro

Sources/Testing/CMakeLists.txt

@@ -112,8 +112,9 @@ else()
     "SHELL:$<$<COMPILE_LANGUAGE:Swift>:-plugin-path ${BINARY_DIR}>")
 endif()
 
-# TODO: @rpath-relative install name
-# This may or may not involve the `-(no-)toolchain-stdlib-rpath` Swift flag.
+target_compile_options(Testing PRIVATE "-no-toolchain-stdlib-rpath")
+# TODO: Finalize
+set_property(TARGET Testing PROPERTY INSTALL_RPATH "$ORIGIN")
 
 include(SwiftModuleInstallation)
 # TODO: Finalize the install path

Sources/TestingMacros/CMakeLists.txt

@@ -59,6 +59,11 @@ if(SwiftTesting_BuildMacrosAsExecutables)
 else()
   add_library(TestingMacros SHARED)
 
+  target_link_options(TestingMacros PRIVATE "-no-toolchain-stdlib-rpath")
+  # Not setting RPATH requires all the dependencies are already loaded in the
+  # process, because 'plugin' directory wouldn't contain any dependencies.
+  set_property(TARGET TestingMacros PROPERTY INSTALL_RPATH)
+
   # Install the macro plugin to the default location.
   #
   # This is not the plugin's actual, final install location -- it's only