[CMake] fix runpath for ELF platforms

Remove the absolute path to the host toolchain's stdlib from the three Foundation
shared libraries. Also, add it as a CMake BUILD_PATH to plutil, so that it's
removed upon installation (disabled for now).

Author: finagolfin

Sources/Foundation/CMakeLists.txt

@@ -157,6 +157,8 @@ if(CMAKE_SYSTEM_NAME STREQUAL Windows)
   add_dependencies(Foundation CoreFoundationResources)
   target_link_options(Foundation PRIVATE
     $<TARGET_OBJECTS:CoreFoundationResources>)
+elseif(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_options(Foundation PRIVATE "SHELL:-no-toolchain-stdlib-rpath")
 endif()
 
 

Sources/FoundationNetworking/CMakeLists.txt

@@ -66,6 +66,10 @@ set_target_properties(FoundationNetworking PROPERTIES
   Swift_MODULE_DIRECTORY ${CMAKE_BINARY_DIR}/swift
   INTERFACE_INCLUDE_DIRECTORIES ${CMAKE_BINARY_DIR}/swift)
 
+if(NOT CMAKE_SYSTEM_NAME MATCHES "Darwin|Windows")
+  target_link_options(FoundationNetworking PRIVATE "SHELL:-no-toolchain-stdlib-rpath")
+endif()
+
 
 set_property(GLOBAL APPEND PROPERTY Foundation_EXPORTS FoundationNetworking)
 install(TARGETS FoundationNetworking

Sources/FoundationXML/CMakeLists.txt

@@ -20,6 +20,10 @@ set_target_properties(FoundationXML PROPERTIES
   Swift_MODULE_DIRECTORY ${CMAKE_BINARY_DIR}/swift
   INTERFACE_INCLUDE_DIRECTORIES ${CMAKE_BINARY_DIR}/swift)
 
+if(NOT CMAKE_SYSTEM_NAME MATCHES "Darwin|Windows")
+  target_link_options(FoundationXML PRIVATE "SHELL:-no-toolchain-stdlib-rpath")
+endif()
+
 
 set_property(GLOBAL APPEND PROPERTY Foundation_EXPORTS FoundationXML)
 install(TARGETS FoundationXML

Sources/Tools/plutil/CMakeLists.txt

@@ -2,6 +2,31 @@ add_executable(plutil
   main.swift)
 target_link_libraries(plutil PRIVATE
   Foundation)
+
+# On ELF platforms, remove the absolute rpath to the host toolchain's stdlib, then add it
+# back temporarily as a BUILD_RPATH just for the tests. Disabled for now, as BUILD_RPATH
+# doesn't work for executables with CMake 3.16 on the CI.
+if(FALSE) #NOT CMAKE_SYSTEM_NAME MATCHES "Darwin|Windows")
+  target_link_options(plutil PRIVATE "SHELL:-no-toolchain-stdlib-rpath")
+
+  # This assumes the host is the target, pass a target flag when cross-compiling.
+  execute_process(
+    COMMAND ${CMAKE_Swift_COMPILER} -print-target-info
+    OUTPUT_VARIABLE output
+    ERROR_VARIABLE error_output
+    RESULT_VARIABLE result
+  )
+  if(NOT ${result} EQUAL 0)
+    message(FATAL_ERROR "Error getting target info with\n"
+      "  `${CMAKE_Swift_COMPILER} -print-target-info`\n"
+      "Error:\n"
+      "  ${error_output}")
+  endif()
+
+  string(REGEX MATCH "\"runtimeLibraryPaths\": \\[\n\ +\"([^\"]+)\"" path ${output})
+  set_target_properties(plutil PROPERTIES BUILD_RPATH ${CMAKE_MATCH_1})
+endif()
+
 set_target_properties(plutil PROPERTIES
   INSTALL_RPATH "$ORIGIN/../lib/swift/$<LOWER_CASE:${CMAKE_SYSTEM_NAME}>")