[libc++] Add a per-target flag to include the generated config_site

This allows propagating the include automatically to targets that
depend on one of the libc++ targets such as the benchmarks. Note
that the GoogleBenchmark build itself still needs to manually specify
the -include, since I don't know of any way to have an external project
link against one of the libc++ targets (which would propagate the -include
automatically).

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@373631 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -809,21 +809,21 @@ if (LIBCXX_NEEDS_SITE_CONFIG)
   configure_file("include/__config_site.in"
                  "${site_config_path}"
                  @ONLY)
-
-  # Provide the config definitions by included the generated __config_site
-  # file at compile time.
-  if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC")
-    add_compile_flags("/FI\"${LIBCXX_BINARY_DIR}/__config_site\"")
-  else()
-    add_compile_flags("-include ${LIBCXX_BINARY_DIR}/__config_site")
-  endif()
-else()
-  if (EXISTS "${site_config_path}")
-    message(STATUS "Removing stale site configuration ${site_config_path}")
-    file(REMOVE "${site_config_path}")
-  endif()
+elseif(EXISTS "${site_config_path}")
+  message(STATUS "Removing stale site configuration ${site_config_path}")
+  file(REMOVE "${site_config_path}")
 endif()
 
+function(cxx_add_config_site target)
+  if (LIBCXX_NEEDS_SITE_CONFIG)
+    if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC" OR "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC")
+      target_compile_options(${target} PUBLIC "/FI\"${site_config_path}\"")
+    else()
+      target_compile_options(${target} PUBLIC "-include${site_config_path}")
+    endif()
+  endif()
+endfunction()
+
 #===============================================================================
 # Setup Source Code And Tests
 #===============================================================================

benchmarks/CMakeLists.txt

@@ -95,10 +95,6 @@ set(BENCHMARK_TEST_LIBCXX_COMPILE_FLAGS
     ${SANITIZER_FLAGS}
     -Wno-user-defined-literals
 )
-if (LIBCXX_NEEDS_SITE_CONFIG)
-  list(APPEND BENCHMARK_TEST_LIBCXX_COMPILE_FLAGS
-      -include "${LIBCXX_BINARY_DIR}/__config_site")
-endif()
 
 set(BENCHMARK_TEST_LIBCXX_LINK_FLAGS
     -nodefaultlibs

src/CMakeLists.txt

@@ -234,6 +234,7 @@ if (LIBCXX_ENABLE_SHARED)
   cxx_set_common_defines(cxx_shared)
   cxx_add_warning_flags(cxx_shared)
   cxx_add_windows_flags(cxx_shared)
+  cxx_add_config_site(cxx_shared)
 
   # Link against LLVM libunwind
   if (LIBCXXABI_USE_LLVM_UNWINDER)
@@ -337,6 +338,7 @@ if (LIBCXX_ENABLE_STATIC)
   cxx_set_common_defines(cxx_static)
   cxx_add_warning_flags(cxx_static)
   cxx_add_windows_flags(cxx_static)
+  cxx_add_config_site(cxx_static)
 
   if (LIBCXX_HERMETIC_STATIC_LIBRARY)
     # If the hermetic library doesn't define the operator new/delete functions