build: support having more than one ICU in use

This allows us to cross-compile the standard library to foreign targets on a
single host.  The ICU dependencies can be specified on the command line on a
per-target basis.  If one is not specified, we fall back to the default search
path and use that for the other targets.

Special thanks to Dimitri Gribenko for the various hints in getting this wired
up.

Author: compnerd

CMakeLists.txt

@@ -154,17 +154,20 @@ set(SWIFT_ANDROID_NDK_GCC_VERSION "" CACHE STRING
   "The GCC version to use when building for Android. Currently only 4.9 is supported.")
 set(SWIFT_ANDROID_SDK_PATH "" CACHE STRING
   "Path to the directory that contains the Android SDK tools that will be passed to the swiftc frontend")
-set(SWIFT_ANDROID_ICU_UC "" CACHE STRING
-  "Path to a directory containing libicuuc.so")
-set(SWIFT_ANDROID_ICU_UC_INCLUDE "" CACHE STRING
-  "Path to a directory containing headers for libicuuc")
-set(SWIFT_ANDROID_ICU_I18N "" CACHE STRING
-  "Path to a directory containing libicui18n.so")
-set(SWIFT_ANDROID_ICU_I18N_INCLUDE "" CACHE STRING
-  "Path to a directory containing headers libicui18n")
 set(SWIFT_ANDROID_DEPLOY_DEVICE_PATH "" CACHE STRING
   "Path on an Android device where build products will be pushed. These are used when running the test suite against the device")
 
+foreach(sdk ANDROID;FREEBSD;LINUX)
+  set(SWIFT_${sdk}_ICU_UC "" CACHE STRING
+      "Path to a directory containing the icuuc library for ${sdk}")
+  set(SWIFT_${sdk}_ICU_UC_INCLUDE "" CACHE STRING
+      "Path to a directory containing headers for icuuc for ${sdk}")
+  set(SWIFT_${sdk}_ICU_I18N "" CACHE STRING
+      "Path to a directory containing the icui18n library for ${sdk}")
+  set(SWIFT_${sdk}_ICU_I18N_INCLUDE "" CACHE STRING
+      "Path to a directory containing headers icui18n for ${sdk}")
+endforeach()
+
 #
 # User-configurable Darwin-specific options.
 #

cmake/modules/AddSwift.cmake

@@ -291,12 +291,18 @@ function(_add_variant_link_flags)
     list(APPEND result
         "-ldl"
         "-L${SWIFT_ANDROID_NDK_PATH}/toolchains/arm-linux-androideabi-${SWIFT_ANDROID_NDK_GCC_VERSION}/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/${SWIFT_ANDROID_NDK_GCC_VERSION}.x"
-        "${SWIFT_ANDROID_NDK_PATH}/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a/libc++_shared.so"
-        "-L${SWIFT_ANDROID_ICU_UC}" "-L${SWIFT_ANDROID_ICU_I18N}")
+        "${SWIFT_ANDROID_NDK_PATH}/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a/libc++_shared.so")
   else()
     list(APPEND result "-lobjc")
   endif()
 
+  if(NOT "${SWIFT_${LFLAGS_SDK}_ICU_UC}" STREQUAL "")
+    list(APPEND result "-L${SWIFT_${sdk}_ICU_UC}")
+  endif()
+  if(NOT "${SWIFT_${LFLAGS_SDK}_ICU_I18N}" STREQUAL "")
+    list(APPEND result "-L${SWIFT_${sdk}_ICU_I18N}")
+  endif()
+
   set("${LFLAGS_RESULT_VAR_NAME}" "${result}" PARENT_SCOPE)
 endfunction()
 
@@ -513,7 +519,7 @@ function(_add_swift_library_single target name)
     message(FATAL_ERROR
         "Either SHARED, STATIC, or OBJECT_LIBRARY must be specified")
   endif()
-  
+
   # Determine the subdirectory where this library will be installed.
   set(SWIFTLIB_SINGLE_SUBDIR
       "${SWIFT_SDK_${SWIFTLIB_SINGLE_SDK}_LIB_SUBDIR}/${SWIFTLIB_SINGLE_ARCHITECTURE}")
@@ -651,6 +657,17 @@ function(_add_swift_library_single target name)
       ${SWIFTLIB_SINGLE_XCODE_WORKAROUND_SOURCES}
       ${SWIFT_SECTIONS_OBJECT_END})
 
+  if(SWIFTLIB_SINGLE_TARGET_LIBRARY)
+    if(NOT "${SWIFT_${SWIFTLIB_SINGLE_SDK}_ICU_UC_INCLUDE}" STREQUAL "")
+      set_property(TARGET "${target}" APPEND_STRING
+          PROPERTY INCLUDE_DIRECTORIES "${SWIFT_${SWIFTLIB_SINGLE_SDK}_ICU_UC_INCLUDE}")
+    endif()
+    if(NOT "${SWIFT_${SWIFTLIB_SINGLE_SDK}_ICU_I18N_INCLUDE}" STREQUAL "")
+      set_property(TARGET "${target}" APPEND_STRING
+          PROPERTY INCLUDE_DIRECTORIES "${SWIFT_${SWIFTLIB_SINGLE_SDK}_ICU_I18N_INCLUDE}")
+    endif()
+  endif()
+
   # The section metadata objects are generated sources, and we need to tell CMake
   # not to expect to find them prior to their generation.
   if("${SWIFTLIB_SINGLE_SDK}" STREQUAL "LINUX" OR

cmake/modules/FindICU.cmake

@@ -25,12 +25,16 @@ foreach(MODULE ${ICU_FIND_COMPONENTS})
   endif()
 endforeach()
 
-if(NOT "${SWIFT_ANDROID_ICU_UC_INCLUDE}" STREQUAL "")
-  set(ICU_UC_INCLUDE_DIR "${SWIFT_ANDROID_ICU_UC_INCLUDE}")
-endif()
-if(NOT "${SWIFT_ANDROID_ICU_I18N_INCLUDE}" STREQUAL "")
-  set(ICU_I18N_INCLUDE_DIR "${SWIFT_ANDROID_ICU_I18N_INCLUDE}")
-endif()
+foreach(sdk ANDROID;FREEBSD;LINUX)
+  foreach(MODULE ${ICU_FIND_COMPONENTS})
+    if("${SWIFT_${sdk}_ICU_${MODULE}_INCLUDE}" STREQUAL "")
+      set(SWIFT_${sdk}_ICU_${MODULE}_INCLUDE ${ICU_${MODULE}_INCLUDE_DIRS})
+    endif()
+    if("${SWIFT_${sdk}_ICU_${MODULE}}" STREQUAL "")
+      set(SWIFT_${sdk}_ICU_${MODULE} ${ICU_${MODULE}_LIBRARY})
+    endif()
+  endforeach()
+endforeach()
 
 find_package_handle_standard_args(ICU DEFAULT_MSG ${ICU_REQUIRED})
 mark_as_advanced(${ICU_REQUIRED})

stdlib/public/stubs/CMakeLists.txt

@@ -12,8 +12,6 @@ else()
   find_package(ICU REQUIRED COMPONENTS uc i18n)
   set(swift_stubs_unicode_normalization_sources
       UnicodeNormalization.cpp)
-  include_directories(
-      ${ICU_UC_INCLUDE_DIR} ${ICU_I18N_INCLUDE_DIR})
 endif()
 
 add_swift_library(swiftStdlibStubs OBJECT_LIBRARY TARGET_LIBRARY