libc++: add `-include` or `/FI` to the interface compile definitions

[compnerd]

Summary

This ensures that when libcxx_shared or libcxx_static the site configuration is always included as appropriate.

[smeenai]

When libc++ is installed, the __config_site and __config are concatenated to make a single __config. I'm imagining this is specific to using libc++ from the build tree? If so, you should use INTERFACE_INCLUDE_DIRECTORIES and $<BUILD_INTERFACE:...> to limit it to builds.

[compnerd]

Hmm, yes, it is for use from the build tree. I don't see how INTERFACE_INCLUDE_DIRECTORIES can do a -include though. It has to be INTERFACE_COMPILE_OPTIONS or INTERFACE_COMPILE_DEFINITIONS.

[smeenai]

In D65831#1619712, @compnerd wrote:

Hmm, yes, it is for use from the build tree. I don't see how INTERFACE_INCLUDE_DIRECTORIES can do a -include though. It has to be INTERFACE_COMPILE_OPTIONS or INTERFACE_COMPILE_DEFINITIONS.

Sorry, that was me not thinking properly :D The comment about BUILD_INTERFACE stills stands though.

src/CMakeLists.txt

 endfunction()
 
 split_list(LIBCXX_COMPILE_FLAGS)
 split_list(LIBCXX_LINK_FLAGS)
 
 # Build the shared library.
 if (LIBCXX_ENABLE_SHARED)
   add_library(cxx_shared SHARED ${exclude_from_all} ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
+  set_target_properties(cxx_shared PROPERTIES
+    INTERFACE_COMPILE_DEFINITIONS
+      $<$<CXX_COMPILER_ID:MSVC>:/FI>
+      $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-include>
+      ${LIBCXX_BINARY_DIR}/__config_site)
   if(COMMAND llvm_setup_rpath)
     llvm_setup_rpath(cxx_shared)
   endif()
   cxx_link_system_libraries(cxx_shared)
   target_link_libraries(cxx_shared PRIVATE ${LIBCXX_LIBRARIES})
   set_target_properties(cxx_shared
     PROPERTIES
       COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
if(WIN32 AND NOT MINGW AND NOT "${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Windows")
     set_target_properties(cxx_shared PROPERTIES
                           APPEND_STRING PROPERTY LINK_FLAGS " /MANIFEST:NO")
   endif()
 endif()
 
 # Build the static library.
 if (LIBCXX_ENABLE_STATIC)
   add_library(cxx_static STATIC ${exclude_from_all} ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
+  set_target_properties(cxx_static PROPERTIES
+    INTERFACE_COMPILE_DEFINITIONS
+      $<$<CXX_COMPILER_ID:MSVC>:/FI>
+      $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-include>
+      ${LIBCXX_BINARY_DIR}/__config_site)
   cxx_link_system_libraries(cxx_static)
   target_link_libraries(cxx_static PRIVATE ${LIBCXX_LIBRARIES})
   set(CMAKE_STATIC_LIBRARY_PREFIX "lib")
   set_target_properties(cxx_static
     PROPERTIES
       COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
       LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
       OUTPUT_NAME   "c++"
set(LIBCXX_EXPERIMENTAL_SOURCES
     experimental/memory_resource.cpp
     )
   add_library(cxx_experimental STATIC ${LIBCXX_EXPERIMENTAL_SOURCES})
   if (LIBCXX_ENABLE_SHARED)
     target_link_libraries(cxx_experimental cxx_shared)
   else()
     target_link_libraries(cxx_experimental cxx_static)
   endif()
+  set_target_properties(cxx_experimental PROPERTIES
+    INTERFACE_COMPILE_DEFINITIONS
+      $<$<CXX_COMPILER_ID:MSVC>:/FI>
+      $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-include>
+      ${LIBCXX_BINARY_DIR}/__config_site)
 
   set(experimental_flags "${LIBCXX_COMPILE_FLAGS}")
   check_flag_supported(-std=c++14)
   if (NOT MSVC AND LIBCXX_SUPPORTS_STD_EQ_CXX14_FLAG)
     string(REPLACE "-std=c++11" "-std=c++14" experimental_flags "${LIBCXX_COMPILE_FLAGS}")
   endif()
   set_target_properties(cxx_experimental
     PROPERTIES
       COMPILE_FLAGS "${experimental_flags}"
       OUTPUT_NAME   "c++experimental"
   )
 endif()
 
 if (LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY)
   file(GLOB LIBCXX_EXTERNAL_THREADING_SUPPORT_SOURCES ../test/support/external_threads.cpp)
 
   if (LIBCXX_ENABLE_SHARED)
     add_library(cxx_external_threads SHARED ${LIBCXX_EXTERNAL_THREADING_SUPPORT_SOURCES})
   else()
     add_library(cxx_external_threads STATIC ${LIBCXX_EXTERNAL_THREADING_SUPPORT_SOURCES})
   endif()
+  set_target_properties(cxx_external_threads PROPERTIES
+    INTERFACE_COMPILE_DEFINITIONS
+      $<$<CXX_COMPILER_ID:MSVC>:/FI>
+      $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-include>
+      ${LIBCXX_BINARY_DIR}/__config_site)
 
   set_target_properties(cxx_external_threads
     PROPERTIES
       LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
       COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
       OUTPUT_NAME   "c++external_threads"
   )
 endif()