build: cleanup some of the link rules

Many of the options were in place due to the legacy build.  Linking
against the imported libraries will both link and include the paths.
Furthermore, now with proper Swift support, it is possible to have the
library linking be computed transitively.  Avoid the double dependency
checking.  Although libdispatch is also used by Foundation, allow the
autolinking to take care of that for the Foundation library as we do not
explicitly link against dispatch anywhere.

Author: compnerd

CMakeLists.txt

@@ -26,15 +26,6 @@ endif()
 
 option(BUILD_SHARED_LIBS "build shared libraries" ON)
 
-find_package(CURL CONFIG)
-if(CURL_FOUND)
-  include(CMakeExpandImportedTargets)
-  cmake_expand_imported_targets(CURL_LIBRARIES LIBRARIES CURL::libcurl)
-else()
-  find_package(CURL REQUIRED)
-endif()
-find_package(ICU COMPONENTS uc i18n REQUIRED)
-find_package(LibXml2 REQUIRED)
 find_package(dispatch CONFIG REQUIRED)
 
 include(SwiftSupport)

CoreFoundation/CMakeLists.txt

@@ -379,8 +379,7 @@ target_compile_definitions(CoreFoundation
                              $<$<COMPILE_LANGUAGE:ASM>:CF_CHARACTERSET_UNICODE_DATA_L="CharacterSets/CFUnicodeData-L.mapping">)
 target_include_directories(CoreFoundation
                            PRIVATE
-                             ${PROJECT_SOURCE_DIR}
-                             ${ICU_INCLUDE_DIR})
+                             ${PROJECT_SOURCE_DIR})
 target_link_libraries(CoreFoundation PRIVATE
   Threads::Threads
   ${CMAKE_DL_LIBS}
@@ -390,6 +389,11 @@ if(CMAKE_SYSTEM_NAME STREQUAL Android)
   target_link_libraries(CoreFoundation PRIVATE
     log)
 endif()
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_libraries(CoreFoundation PRIVATE
+    ICU::uc
+    ICU::i18n)
+endif()
 
 add_framework(CFURLSessionInterface
                 ${FRAMEWORK_LIBRARY_TYPE}
@@ -409,10 +413,10 @@ if(CMAKE_SYSTEM_NAME STREQUAL Windows)
                              PRIVATE
                                CURL_STATICLIB)
 endif()
-target_include_directories(CFURLSessionInterface PRIVATE
-  ${CURL_INCLUDE_DIRS})
-target_link_libraries(CFURLSessionInterface PRIVATE
-  ${CURL_LIBRARIES})
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_libraries(CFURLSessionInterface PRIVATE
+    CURL::libcurl)
+endif()
 
 add_framework(CFXMLInterface
                 ${FRAMEWORK_LIBRARY_TYPE}
@@ -427,10 +431,10 @@ add_framework(CFXMLInterface
               SOURCES
                 Parsing.subproj/CFXMLInterface.c)
 add_dependencies(CFXMLInterface CoreFoundation)
-target_include_directories(CFXMLInterface PRIVATE
-  ${LIBXML2_INCLUDE_DIR})
-target_link_libraries(CFXMLInterface PRIVATE
-  ${LIBXML2_LIBRARIES})
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Darwin)
+  target_link_libraries(CFXMLInterface PRIVATE
+    LibXml2::LibXml2)
+endif()
 
 if(CMAKE_SYSTEM_NAME STREQUAL Windows)
   add_library(CoreFoundationResources OBJECT

CoreFoundation/cmake/modules/FindICU.cmake

@@ -140,8 +140,6 @@ target_compile_definitions(Foundation PRIVATE
   DEPLOYMENT_RUNTIME_SWIFT)
 target_compile_options(Foundation PUBLIC
   "SHELL:-Xcc -F${CMAKE_BINARY_DIR}")
-target_compile_options(Foundation PRIVATE
-  "SHELL:-Xcc -I${ICU_INCLUDE_DIR}")
 if(CMAKE_SYSTEM_NAME STREQUAL Windows AND CMAKE_VERSION VERSION_LESS 3.16)
   # Work around for CMake 15 which doesn't link in the resource file
   # target properly
@@ -153,8 +151,6 @@ if(ENABLE_TESTING)
     -enable-testing)
 endif()
 target_link_libraries(Foundation PRIVATE
-  ${ICU_UC_LIBRARY}
-  ${ICU_I18N_LIBRARY}
   CoreFoundation
   uuid)
 target_link_libraries(Foundation PUBLIC
@@ -219,8 +215,6 @@ if(ENABLE_TESTING)
     -enable-testing)
 endif()
 target_link_libraries(FoundationNetworking PRIVATE
-  ${CURL_LIBRARIES}
-  ${ZLIB_LIBRARIES}
   Foundation
   CFURLSessionInterface)
 set_target_properties(FoundationNetworking PROPERTIES
@@ -245,7 +239,6 @@ if(ENABLE_TESTING)
     -enable-testing)
 endif()
 target_link_libraries(FoundationXML PRIVATE
-  ${LIBXML2_LIBRARIES}
   Foundation
   CFXMLInterface)
 set_target_properties(FoundationXML PROPERTIES