[libcxx] Support LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY + LIBCXX_ENABLE_ABI_LINKER_SCRIPT

[nikic]

Summary

Currently if both LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY (only applies to static library) and LIBCXX_ENABLE_ABI_LINKER_SCRIPT (only applies to shared library) are enabled, the former will be silently ignored. The shared library will use a linker script, while the static library fails to link libc++abi.a entirely.

This is caused by what appears to be an implementation bug: The LIBCXX_STATICALLY_LINK_ABI_IN_*_LIBRARY options are declared as dependent options of LIBCXX_ENABLE_STATIC_ABI_LIBRARY, rather than simply using it as the default value.

Of course, the combination of LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY and LIBCXX_ENABLE_ABI_LINKER_SCRIPT still results in a cmake error, because these would be conflicting requests for the shared library.

[nikic]

libcxx/CMakeLists.txt

384

Dropped this entirely, as python is no longer used for this purpose, as far as I know. This is now handled via object targets.

[ldionne]

This makes sense to me regardless of the direction we end up taking with D125683.

libcxx/CMakeLists.txt

 if (NOT "${LIBCXX_CXX_ABI}" IN_LIST LIBCXX_SUPPORTED_ABI_LIBRARIES)
   message(FATAL_ERROR "Unsupported C++ ABI library: '${LIBCXX_CXX_ABI}'. Supported values are ${LIBCXX_SUPPORTED_ABI_LIBRARIES}.")
 endif()
 
 option(LIBCXX_ENABLE_STATIC_ABI_LIBRARY
   "Use a static copy of the ABI library when linking libc++.
    This option cannot be used with LIBCXX_ENABLE_ABI_LINKER_SCRIPT." OFF)
 
-cmake_dependent_option(LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY
-  "Statically link the ABI library to static library" ON
-  "LIBCXX_ENABLE_STATIC_ABI_LIBRARY" OFF)
-
-cmake_dependent_option(LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY
-  "Statically link the ABI library to shared library" ON
-  "LIBCXX_ENABLE_STATIC_ABI_LIBRARY" OFF)
+option(LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY
+  "Statically link the ABI library to static library"
+  ${LIBCXX_ENABLE_STATIC_ABI_LIBRARY})
+
+option(LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY
+  "Statically link the ABI library to shared library"
+  ${LIBCXX_ENABLE_STATIC_ABI_LIBRARY})
 
 # Generate and install a linker script inplace of libc++.so. The linker script
 # will link libc++ to the correct ABI library. This option is on by default
-# on UNIX platforms other than Apple unless 'LIBCXX_ENABLE_STATIC_ABI_LIBRARY'
-# is on. This option is also disabled when the ABI library is not specified
-# or is specified to be "none".
+# on UNIX platforms other than Apple unless
+# 'LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY' is on. This option is also
+# disabled when the ABI library is not specified or is specified to be "none".
 set(ENABLE_LINKER_SCRIPT_DEFAULT_VALUE OFF)
 if (LLVM_HAVE_LINK_VERSION_SCRIPT AND NOT LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY
       AND NOT LIBCXX_CXX_ABI STREQUAL "none"
       AND Python3_EXECUTABLE
       AND LIBCXX_ENABLE_SHARED)
     set(ENABLE_LINKER_SCRIPT_DEFAULT_VALUE ON)
 endif()
 

 endif()
 
 # Ensure LLVM_USE_SANITIZER is not specified when LIBCXX_GENERATE_COVERAGE
 # is ON.
 if (LLVM_USE_SANITIZER AND LIBCXX_GENERATE_COVERAGE)
   message(FATAL_ERROR "LLVM_USE_SANITIZER cannot be used with LIBCXX_GENERATE_COVERAGE")
 endif()
 
-# Warn users that LIBCXX_ENABLE_STATIC_ABI_LIBRARY is an experimental option.
-if (LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
-  message(WARNING "LIBCXX_ENABLE_STATIC_ABI_LIBRARY is an experimental option")
-  if (LIBCXX_ENABLE_STATIC AND NOT Python3_EXECUTABLE)
-    message(FATAL_ERROR "LIBCXX_ENABLE_STATIC_ABI_LIBRARY requires python but it was not found.")
-  endif()
-endif()
-
 if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
     if (APPLE)
       message(FATAL_ERROR "LIBCXX_ENABLE_ABI_LINKER_SCRIPT cannot be used on APPLE targets")
     endif()
     if (NOT LIBCXX_ENABLE_SHARED)
       message(FATAL_ERROR "LIBCXX_ENABLE_ABI_LINKER_SCRIPT is only available for shared library builds.")
     endif()
 endif()
 
 if (LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY AND LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
     message(FATAL_ERROR "Conflicting options given.
-        LIBCXX_ENABLE_STATIC_ABI_LIBRARY cannot be specified with
+        LIBCXX_STATICALLY_LINK_ABI_IN_SHARED_LIBRARY cannot be specified with
         LIBCXX_ENABLE_ABI_LINKER_SCRIPT")
 endif()
 
 if (LIBCXX_ABI_FORCE_ITANIUM AND LIBCXX_ABI_FORCE_MICROSOFT)
   message(FATAL_ERROR "Only one of LIBCXX_ABI_FORCE_ITANIUM and LIBCXX_ABI_FORCE_MICROSOFT can be specified.")
 endif ()
 
 #===============================================================================