[runtimes] Always define cxx_shared, cxx_static & other targets

However, mark them as EXCLUDE_FROM_ALL when we don't want to build them.
Simply declaring the targets should be of no harm, and it allows other
projects to mention these targets regardless of whether they end up
being built or not.

While the diff may not make that obvious, this patch basically
moves the definition of e.g. `cxx_shared` out of the `if (LIBCXX_ENABLE_SHARED)`
and instead marks it as `EXCLUDE_FROM_ALL` conditionally on whether
LIBCXX_ENABLE_SHARED is passed. It then does the same for libunwind
and libc++abi targets.

Differential Revision: https://reviews.llvm.org/D134221

Author: ldionne

libcxx/cmake/caches/AIX.cmake

@@ -17,3 +17,10 @@ set(LIBCXX_CXX_ABI libcxxabi CACHE STRING "")
 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
 set(LIBUNWIND_ENABLE_SHARED ON CACHE BOOL "")
 set(LIBUNWIND_ENABLE_STATIC OFF CACHE BOOL "")
+
+# On AIX, both shared and static libraries are archived. As a result, both the static and the shared targets end
+# up with a `.a` suffix, which conflict. To workaround that, we set a different output name for the static
+# libraries, which we never actually build anyway. For more information, see https://gitlab.kitware.com/cmake/cmake/-/issues/19494.
+set(LIBCXX_STATIC_OUTPUT_NAME "c++-static" CACHE STRING "")
+set(LIBCXXABI_STATIC_OUTPUT_NAME "c++abi-static" CACHE STRING "")
+set(LIBUNWIND_STATIC_OUTPUT_NAME "unwind-static" CACHE STRING "")

libcxx/src/CMakeLists.txt

@@ -147,10 +147,6 @@ if (LIBCXX_CONFIGURE_IDE)
   endif()
 endif()
 
-if(NOT LIBCXX_INSTALL_LIBRARY)
-  set(exclude_from_all EXCLUDE_FROM_ALL)
-endif()
-
 if (LIBCXX_GENERATE_COVERAGE AND NOT LIBCXX_COVERAGE_LIBRARY)
   find_compiler_rt_library(profile LIBCXX_COVERAGE_LIBRARY)
 endif()
@@ -195,139 +191,146 @@ 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})
-  target_include_directories(cxx_shared PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
-  target_link_libraries(cxx_shared PUBLIC cxx-headers
-                                   PRIVATE ${LIBCXX_LIBRARIES})
-  set_target_properties(cxx_shared
-    PROPERTIES
-      COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
-      LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
-      OUTPUT_NAME   "${LIBCXX_SHARED_OUTPUT_NAME}"
-      VERSION       "${LIBCXX_LIBRARY_VERSION}"
-      SOVERSION     "${LIBCXX_ABI_VERSION}"
-      DEFINE_SYMBOL ""
+#
+add_library(cxx_shared SHARED $<$<NOT:$<BOOL:LIBCXX_ENABLE_SHARED>>:EXCLUDE_FROM_ALL> ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
+target_include_directories(cxx_shared PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+target_link_libraries(cxx_shared PUBLIC cxx-headers
+                                 PRIVATE ${LIBCXX_LIBRARIES})
+set_target_properties(cxx_shared
+  PROPERTIES
+    COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
+    LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
+    OUTPUT_NAME   "${LIBCXX_SHARED_OUTPUT_NAME}"
+    VERSION       "${LIBCXX_LIBRARY_VERSION}"
+    SOVERSION     "${LIBCXX_ABI_VERSION}"
+    DEFINE_SYMBOL ""
+)
+cxx_add_common_build_flags(cxx_shared)
+cxx_set_common_defines(cxx_shared)
+
+if(ZOS)
+  add_custom_command(TARGET cxx_shared POST_BUILD
+    COMMAND
+      ${LIBCXX_SOURCE_DIR}/utils/zos_rename_dll_side_deck.sh
+      $<TARGET_LINKER_FILE_NAME:cxx_shared> $<TARGET_FILE_NAME:cxx_shared> "${LIBCXX_DLL_NAME}"
+    COMMENT "Rename dll name inside the side deck file"
+    WORKING_DIRECTORY $<TARGET_FILE_DIR:cxx_shared>
   )
-  cxx_add_common_build_flags(cxx_shared)
-  cxx_set_common_defines(cxx_shared)
-
-  if(ZOS)
-    add_custom_command(TARGET cxx_shared POST_BUILD
-      COMMAND
-        ${LIBCXX_SOURCE_DIR}/utils/zos_rename_dll_side_deck.sh
-        $<TARGET_LINKER_FILE_NAME:cxx_shared> $<TARGET_FILE_NAME:cxx_shared> "${LIBCXX_DLL_NAME}"
-      COMMENT "Rename dll name inside the side deck file"
-      WORKING_DIRECTORY $<TARGET_FILE_DIR:cxx_shared>
-    )
-  endif()
+endif()
 
-  # Link against libc++abi
-  if (LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY)
-    target_link_libraries(cxx_shared PRIVATE libcxx-abi-shared-objects)
-  else()
-    target_link_libraries(cxx_shared PUBLIC libcxx-abi-shared)
-  endif()
+# Link against libc++abi
+if (LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY)
+  target_link_libraries(cxx_shared PRIVATE libcxx-abi-shared-objects)
+else()
+  target_link_libraries(cxx_shared PUBLIC libcxx-abi-shared)
+endif()
 
-  # Maybe re-export symbols from libc++abi
-  # In particular, we don't re-export the symbols if libc++abi is merged statically
-  # into libc++ because in that case there's no dylib to re-export from.
-  if (APPLE AND LIBCXX_CXX_ABI STREQUAL "libcxxabi"
-            AND NOT DEFINED LIBCXX_OSX_REEXPORT_LIBCXXABI_SYMBOLS
-            AND NOT LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY)
-    set(LIBCXX_OSX_REEXPORT_LIBCXXABI_SYMBOLS ON)
-  endif()
+# Maybe re-export symbols from libc++abi
+# In particular, we don't re-export the symbols if libc++abi is merged statically
+# into libc++ because in that case there's no dylib to re-export from.
+if (APPLE AND LIBCXX_CXX_ABI STREQUAL "libcxxabi"
+          AND NOT DEFINED LIBCXX_OSX_REEXPORT_LIBCXXABI_SYMBOLS
+          AND NOT LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY)
+  set(LIBCXX_OSX_REEXPORT_LIBCXXABI_SYMBOLS ON)
+endif()
 
-  if (LIBCXX_OSX_REEXPORT_LIBCXXABI_SYMBOLS)
-    target_link_libraries(cxx_shared PRIVATE
-      "-Wl,-unexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/libc++unexp.exp"
-      "-Wl,-reexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/libc++abi.exp"
-      "-Wl,-force_symbols_not_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/notweak.exp"
-      "-Wl,-force_symbols_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/weak.exp")
+if (LIBCXX_OSX_REEXPORT_LIBCXXABI_SYMBOLS)
+  target_link_libraries(cxx_shared PRIVATE
+    "-Wl,-unexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/libc++unexp.exp"
+    "-Wl,-reexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/libc++abi.exp"
+    "-Wl,-force_symbols_not_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/notweak.exp"
+    "-Wl,-force_symbols_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/../lib/weak.exp")
 
-    target_link_libraries(cxx_shared PRIVATE $<TARGET_NAME_IF_EXISTS:cxxabi-reexports>)
-  endif()
+  target_link_libraries(cxx_shared PRIVATE $<TARGET_NAME_IF_EXISTS:cxxabi-reexports>)
+endif()
 
-  # Generate a linker script in place of a libc++.so symlink.
-  if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
-    set(link_libraries)
-
-    set(imported_libname "$<TARGET_PROPERTY:libcxx-abi-shared,IMPORTED_LIBNAME>")
-    set(output_name "$<TARGET_PROPERTY:libcxx-abi-shared,OUTPUT_NAME>")
-    string(APPEND link_libraries "${CMAKE_LINK_LIBRARY_FLAG}$<IF:$<BOOL:${imported_libname}>,${imported_libname},${output_name}>")
-
-    # TODO: Move to the same approach as above for the unwind library
-    if (LIBCXXABI_USE_LLVM_UNWINDER)
-      if (LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY)
-        # libunwind is already included in libc++abi
-      elseif (TARGET unwind_shared OR HAVE_LIBUNWIND)
-        string(APPEND link_libraries " ${CMAKE_LINK_LIBRARY_FLAG}$<TARGET_PROPERTY:unwind_shared,OUTPUT_NAME>")
-      else()
-        string(APPEND link_libraries " ${CMAKE_LINK_LIBRARY_FLAG}unwind")
-      endif()
+# Generate a linker script in place of a libc++.so symlink.
+if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
+  set(link_libraries)
+
+  set(imported_libname "$<TARGET_PROPERTY:libcxx-abi-shared,IMPORTED_LIBNAME>")
+  set(output_name "$<TARGET_PROPERTY:libcxx-abi-shared,OUTPUT_NAME>")
+  string(APPEND link_libraries "${CMAKE_LINK_LIBRARY_FLAG}$<IF:$<BOOL:${imported_libname}>,${imported_libname},${output_name}>")
+
+  # TODO: Move to the same approach as above for the unwind library
+  if (LIBCXXABI_USE_LLVM_UNWINDER)
+    if (LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_SHARED_LIBRARY)
+      # libunwind is already included in libc++abi
+    elseif (TARGET unwind_shared OR HAVE_LIBUNWIND)
+      string(APPEND link_libraries " ${CMAKE_LINK_LIBRARY_FLAG}$<TARGET_PROPERTY:unwind_shared,OUTPUT_NAME>")
+    else()
+      string(APPEND link_libraries " ${CMAKE_LINK_LIBRARY_FLAG}unwind")
     endif()
-
-    set(linker_script "INPUT($<TARGET_SONAME_FILE_NAME:cxx_shared> ${link_libraries})")
-    add_custom_command(TARGET cxx_shared POST_BUILD
-      COMMAND "${CMAKE_COMMAND}" -E remove "$<TARGET_LINKER_FILE:cxx_shared>"
-      COMMAND "${CMAKE_COMMAND}" -E echo "${linker_script}" > "$<TARGET_LINKER_FILE:cxx_shared>"
-      COMMENT "Generating linker script: '${linker_script}' as file $<TARGET_LINKER_FILE:cxx_shared>"
-      VERBATIM
-    )
   endif()
 
+  set(linker_script "INPUT($<TARGET_SONAME_FILE_NAME:cxx_shared> ${link_libraries})")
+  add_custom_command(TARGET cxx_shared POST_BUILD
+    COMMAND "${CMAKE_COMMAND}" -E remove "$<TARGET_LINKER_FILE:cxx_shared>"
+    COMMAND "${CMAKE_COMMAND}" -E echo "${linker_script}" > "$<TARGET_LINKER_FILE:cxx_shared>"
+    COMMENT "Generating linker script: '${linker_script}' as file $<TARGET_LINKER_FILE:cxx_shared>"
+    VERBATIM
+  )
+endif()
+
+if (LIBCXX_ENABLE_SHARED)
   list(APPEND LIBCXX_BUILD_TARGETS "cxx_shared")
-  if(WIN32 AND NOT MINGW AND NOT "${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Windows")
-    # Since we most likely do not have a mt.exe replacement, disable the
-    # manifest bundling.  This allows a normal cmake invocation to pass which
-    # will attempt to use the manifest tool to generate the bundled manifest
-    set_target_properties(cxx_shared PROPERTIES
-                          APPEND_STRING PROPERTY LINK_FLAGS " /MANIFEST:NO")
-  endif()
+endif()
+if(WIN32 AND NOT MINGW AND NOT "${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Windows")
+  # Since we most likely do not have a mt.exe replacement, disable the
+  # manifest bundling.  This allows a normal cmake invocation to pass which
+  # will attempt to use the manifest tool to generate the bundled manifest
+  set_target_properties(cxx_shared PROPERTIES
+                        APPEND_STRING PROPERTY LINK_FLAGS " /MANIFEST:NO")
 endif()
 
 set(CMAKE_STATIC_LIBRARY_PREFIX "lib")
 
+#
 # Build the static library.
-if (LIBCXX_ENABLE_STATIC)
-  add_library(cxx_static STATIC ${exclude_from_all} ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
-  target_include_directories(cxx_static PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
-  target_link_libraries(cxx_static PUBLIC cxx-headers
-                                   PRIVATE ${LIBCXX_LIBRARIES}
-                                   PRIVATE libcxx-abi-static)
-  set_target_properties(cxx_static
-    PROPERTIES
-      COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
-      LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
-      OUTPUT_NAME   "${LIBCXX_STATIC_OUTPUT_NAME}"
-  )
-  cxx_add_common_build_flags(cxx_static)
-  cxx_set_common_defines(cxx_static)
-
-  if (LIBCXX_HERMETIC_STATIC_LIBRARY)
-    # If the hermetic library doesn't define the operator new/delete functions
-    # then its code shouldn't declare them with hidden visibility.  They might
-    # actually be provided by a shared library at link time.
-    if (LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS)
-      append_flags_if_supported(CXX_STATIC_LIBRARY_FLAGS -fvisibility-global-new-delete-hidden)
-    endif()
-    target_compile_options(cxx_static PRIVATE ${CXX_STATIC_LIBRARY_FLAGS})
-    # _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS can be defined in __config_site
-    # too. Define it in the same way here, to avoid redefinition conflicts.
-    target_compile_definitions(cxx_static PRIVATE _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS=)
+#
+add_library(cxx_static STATIC $<$<NOT:$<BOOL:LIBCXX_ENABLE_STATIC>>:EXCLUDE_FROM_ALL> ${LIBCXX_SOURCES} ${LIBCXX_HEADERS})
+target_include_directories(cxx_static PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+target_link_libraries(cxx_static PUBLIC cxx-headers
+                                 PRIVATE ${LIBCXX_LIBRARIES}
+                                 PRIVATE libcxx-abi-static)
+set_target_properties(cxx_static
+  PROPERTIES
+    COMPILE_FLAGS "${LIBCXX_COMPILE_FLAGS}"
+    LINK_FLAGS    "${LIBCXX_LINK_FLAGS}"
+    OUTPUT_NAME   "${LIBCXX_STATIC_OUTPUT_NAME}"
+)
+cxx_add_common_build_flags(cxx_static)
+cxx_set_common_defines(cxx_static)
+
+if (LIBCXX_HERMETIC_STATIC_LIBRARY)
+  # If the hermetic library doesn't define the operator new/delete functions
+  # then its code shouldn't declare them with hidden visibility.  They might
+  # actually be provided by a shared library at link time.
+  if (LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS)
+    append_flags_if_supported(CXX_STATIC_LIBRARY_FLAGS -fvisibility-global-new-delete-hidden)
   endif()
+  target_compile_options(cxx_static PRIVATE ${CXX_STATIC_LIBRARY_FLAGS})
+  # _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS can be defined in __config_site
+  # too. Define it in the same way here, to avoid redefinition conflicts.
+  target_compile_definitions(cxx_static PRIVATE _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS=)
+endif()
 
+if (LIBCXX_ENABLE_STATIC)
   list(APPEND LIBCXX_BUILD_TARGETS "cxx_static")
-  # Attempt to merge the libc++.a archive and the ABI library archive into one.
-  if (LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY)
-    target_link_libraries(cxx_static PRIVATE libcxx-abi-static-objects)
-  endif()
+endif()
+# Attempt to merge the libc++.a archive and the ABI library archive into one.
+if (LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY)
+  target_link_libraries(cxx_static PRIVATE libcxx-abi-static-objects)
 endif()
 
 # Add a meta-target for both libraries.
 add_custom_target(cxx DEPENDS ${LIBCXX_BUILD_TARGETS})
 
+#
+# Build the experimental static library
+#
 set(LIBCXX_EXPERIMENTAL_SOURCES
   experimental/memory_resource.cpp
   format.cpp