Allow building both shared and static library

This change allows building both shared and static version of libc++
in a single build, sharing object files between both versions.

Differential Revision: https://reviews.llvm.org/D23232

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@278068 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -52,6 +52,7 @@ MACRO_ENSURE_OUT_OF_SOURCE_BUILD(
 # Basic options ---------------------------------------------------------------
 option(LIBCXX_ENABLE_ASSERTIONS "Enable assertions independent of build mode." ON)
 option(LIBCXX_ENABLE_SHARED "Build libc++ as a shared library." ON)
+option(LIBCXX_ENABLE_STATIC "Build libc++ as a static library." ON)
 option(LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY "Build libc++experimental.a" ON)
 option(LIBCXX_ENABLE_FILESYSTEM
         "Build filesystem as part of libc++experimental.a" ${LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY})
@@ -68,6 +69,10 @@ option(LIBCXX_INSTALL_EXPERIMENTAL_LIBRARY "Install libc++experimental.a" OFF)
 set(LIBCXX_ABI_VERSION 1 CACHE STRING "ABI version of libc++.")
 option(LIBCXX_ABI_UNSTABLE "Unstable ABI of libc++." OFF)
 
+if (NOT LIBCXX_ENABLE_SHARED AND NOT LIBCXX_ENABLE_STATIC)
+  message(FATAL_ERROR "libc++ must be built as either a shared or static library.")
+endif()
+
 # ABI Library options ---------------------------------------------------------
 set(LIBCXX_CXX_ABI "${LIBCXX_CXX_ABI}" CACHE STRING
     "Specify C++ ABI library to use." FORCE)

docs/BuildingLibcxx.rst

@@ -150,8 +150,15 @@ libc++ specific options
 
   **Default**: ``ON``
 
-  Build libc++ as a shared library. If ``OFF`` is specified then libc++ is
+  Build libc++ as a shared library. Either :option:`LIBCXX_ENABLE_SHARED` or
-  built as a static library.
+  :option:`LIBCXX_ENABLE_STATIC` has to be enabled.
+
+.. option:: LIBCXX_ENABLE_STATIC:BOOL
+
+  **Default**: ``ON``
+
+  Build libc++ as a static library. Either :option:`LIBCXX_ENABLE_SHARED` or
+  :option:`LIBCXX_ENABLE_STATIC` has to be enabled.
 
 .. option:: LIBCXX_LIBDIR_SUFFIX:STRING
 

lib/CMakeLists.txt

@@ -28,16 +28,6 @@ if(NOT LIBCXX_INSTALL_LIBRARY)
   set(exclude_from_all EXCLUDE_FROM_ALL)
 endif()
 
-if (LIBCXX_ENABLE_SHARED)
-  add_library(cxx SHARED ${exclude_from_all} ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
-else()
-  add_library(cxx STATIC ${exclude_from_all} ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
-endif()
-
-if (DEFINED LIBCXX_CXX_ABI_DEPS)
-  add_dependencies(cxx LIBCXX_CXX_ABI_DEPS)
-endif()
-
 #if LIBCXX_CXX_ABI_LIBRARY_PATH is defined we want to add it to the search path.
 add_link_flags_if(LIBCXX_CXX_ABI_LIBRARY_PATH "-L${LIBCXX_CXX_ABI_LIBRARY_PATH}")
 
@@ -139,18 +129,51 @@ if ( APPLE AND (LIBCXX_CXX_ABI_LIBNAME STREQUAL "libcxxabi" OR
   endif()
 endif()
 
-target_link_libraries(cxx ${LIBCXX_LIBRARIES})
 split_list(LIBCXX_COMPILE_FLAGS)
 split_list(LIBCXX_LINK_FLAGS)
 
-set_target_properties(cxx
+# Add a object library that contains the compiled source files.
+add_library(cxx_objects OBJECT ${exclude_from_all} ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
+
+set_target_properties(cxx_objects
   PROPERTIES
     COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
-    LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
+)
-    OUTPUT_NAME   "c++"
+
-    VERSION       "${LIBCXX_ABI_VERSION}.0"
+set(LIBCXX_TARGETS)
-    SOVERSION     "${LIBCXX_ABI_VERSION}"
+
+# Build the shared library.
+if (LIBCXX_ENABLE_SHARED)
+  add_library(cxx_shared SHARED $<TARGET_OBJECTS:cxx_objects>)
+  target_link_libraries(cxx_shared ${LIBCXX_LIBRARIES})
+  set_target_properties(cxx_shared
+    PROPERTIES
+      LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
+      OUTPUT_NAME   "c++"
+      VERSION       "${LIBCXX_ABI_VERSION}.0"
+      SOVERSION     "${LIBCXX_ABI_VERSION}"
   )
+  list(APPEND LIBCXX_TARGETS "cxx_shared")
+endif()
+
+# Build the static library.
+if (LIBCXX_ENABLE_STATIC)
+  add_library(cxx_static STATIC $<TARGET_OBJECTS:cxx_objects>)
+  target_link_libraries(cxx_static ${LIBCXX_LIBRARIES})
+  set_target_properties(cxx_static
+    PROPERTIES
+      LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
+      OUTPUT_NAME   "c++"
+  )
+  list(APPEND LIBCXX_TARGETS "cxx_static")
+endif()
+
+# Add a meta-target for both libraries.
+add_custom_target(cxx DEPENDS ${LIBCXX_TARGETS})
+
+if (DEFINED LIBCXX_CXX_ABI_DEPS)
+  add_dependencies(cxx LIBCXX_CXX_ABI_DEPS)
+endif()
 
 if (LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY)
   file(GLOB LIBCXX_EXPERIMENTAL_SOURCES ../src/experimental/*.cpp)
@@ -158,7 +181,11 @@ if (LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY)
     file(GLOB LIBCXX_FILESYSTEM_SOURCES ../src/experimental/filesystem/*.cpp)
   endif()
   add_library(cxx_experimental STATIC ${LIBCXX_EXPERIMENTAL_SOURCES} ${LIBCXX_FILESYSTEM_SOURCES})
-  target_link_libraries(cxx_experimental cxx)
+  if (LIBCXX_ENABLE_SHARED)
+    target_link_libraries(cxx_experimental cxx_shared)
+  else()
+    target_link_libraries(cxx_experimental cxx_static)
+  endif()
 
   set(experimental_flags "${LIBCXX_COMPILE_FLAGS}")
   check_flag_supported(-std=c++14)
@@ -174,7 +201,7 @@ endif()
 
 # Generate a linker script inplace of a libc++.so symlink. Rerun this command
 # after cxx builds.
-if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
+if (LIBCXX_ENABLE_SHARED AND LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
   # Get the name of the ABI library and handle the case where CXXABI_LIBNAME
   # is a target name and not a library. Ex cxxabi_shared.
   set(SCRIPT_ABI_LIBNAME "${LIBCXX_CXX_ABI_LIBRARY}")
@@ -183,11 +210,11 @@ if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
   endif()
   # Generate a linker script inplace of a libc++.so symlink. Rerun this command
   # after cxx builds.
-  add_custom_command(TARGET cxx POST_BUILD
+  add_custom_command(TARGET cxx_shared POST_BUILD
     COMMAND
       ${PYTHON_EXECUTABLE} ${LIBCXX_SOURCE_DIR}/utils/gen_link_script/gen_link_script.py
     ARGS
-      "$<TARGET_LINKER_FILE:cxx>"
+      "$<TARGET_LINKER_FILE:cxx_shared>"
       "${SCRIPT_ABI_LIBNAME}"
     WORKING_DIRECTORY ${LIBCXX_BUILD_DIR}
   )
@@ -197,13 +224,13 @@ if (LIBCXX_INSTALL_LIBRARY)
   if (LIBCXX_INSTALL_EXPERIMENTAL_LIBRARY)
     set(experimental_lib cxx_experimental)
   endif()
-  install(TARGETS cxx ${experimental_lib}
+  install(TARGETS ${LIBCXX_TARGETS} ${experimental_lib}
     LIBRARY DESTINATION lib${LIBCXX_LIBDIR_SUFFIX} COMPONENT libcxx
     ARCHIVE DESTINATION lib${LIBCXX_LIBDIR_SUFFIX} COMPONENT libcxx
     )
   # NOTE: This install command must go after the cxx install command otherwise
   # it will not be executed after the library symlinks are installed.
-  if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
+  if (LIBCXX_ENABLE_SHARED AND LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
     # Replace the libc++ filename with $<TARGET_LINKER_FILE:cxx>
     # after we required CMake 3.0.
     install(FILES "${LIBCXX_LIBRARY_DIR}/libc++${CMAKE_SHARED_LIBRARY_SUFFIX}"