[libcxx] Fix check-cxx-abilist on OS X

[EricWF]

Summary

Recent commits broke the check-cxx-abilist by changing the default OS X to use -rexport_library instead of -reexport_symbol_list. Apparently -reexport_library doesn't export the symbols into libc++.dylibs symbol table, whereas -reexport_symbol_list does.

This means the change removed ~500 symbols from the symbol table. I've been told this change is non ABI breaking, but it does make it harder to maintain the ABI lists, and hence the ABI.

This patch fixes the issue by switching back to -reexport_symbol_list. It still avoid the issues fixed in r299052 by putting the new/delete symbols in a different symbol list file, which is only exported when LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS in OFF.

[EricWF]

• Remove silly changes to libc++abi2.exp

[smeenai]

Makes sense to me. Some questions inline, but they may not necessitate changes, so I'm accepting.

lib/CMakeLists.txt

166

Do you need to repeat the libc++abi.dylib path? Would it be more appropriate to append this to OSX_RE_EXPORT_LINE?

lib/CMakeLists.txt

if ( CMAKE_OSX_DEPLOYMENT_TARGET STREQUAL "10.6" )
     add_link_flags(
       "-compatibility_version 1"
       "-current_version 1"
       "-install_name /usr/lib/libc++.1.dylib"
       "-Wl,-reexport_library,/usr/lib/libc++abi.dylib"
       "-Wl,-unexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/libc++unexp.exp"
       "/usr/lib/libSystem.B.dylib")
   else()
-    if (LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS)
-        # We can't use the "-reexported_symbols_list" when we build the
-        # new/delete operators as part of the dylib: the linker would fail.
-        set(OSX_RE_EXPORT_LINE "-Wl,-reexport_library,${CMAKE_OSX_SYSROOT}/usr/lib/libc++abi.dylib")
-  elseif (DEFINED CMAKE_OSX_SYSROOT AND NOT CMAKE_OSX_SYSROOT STREQUAL "")
+    if (DEFINED CMAKE_OSX_SYSROOT AND NOT CMAKE_OSX_SYSROOT STREQUAL "")
       list(FIND CMAKE_OSX_ARCHITECTURES "armv7" OSX_HAS_ARMV7)
       if (NOT OSX_HAS_ARMV7 EQUAL -1)
         set(OSX_RE_EXPORT_LINE
           "${CMAKE_OSX_SYSROOT}/usr/lib/libc++abi.dylib"
           "-Wl,-reexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/libc++sjlj-abi.exp")
       else()
         set(OSX_RE_EXPORT_LINE
           "-Wl,-reexport_library,${CMAKE_OSX_SYSROOT}/usr/lib/libc++abi.dylib")
       endif()
     else()
       set(OSX_RE_EXPORT_LINE "/usr/lib/libc++abi.dylib -Wl,-reexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/libc++abi${LIBCXX_LIBCPPABI_VERSION}.exp")
+      if (NOT LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS)
+        add_link_flags("/usr/lib/libc++abi.dylib -Wl,-reexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/libc++abi-new-delete.exp")
+      endif()
     endif()
-
     add_link_flags(
       "-compatibility_version 1"
       "-install_name /usr/lib/libc++.1.dylib"
       "-Wl,-unexported_symbols_list,${CMAKE_CURRENT_SOURCE_DIR}/libc++unexp.exp"
       "${OSX_RE_EXPORT_LINE}"
       "-Wl,-force_symbols_not_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/notweak.exp"
       "-Wl,-force_symbols_weak_list,${CMAKE_CURRENT_SOURCE_DIR}/weak.exp")
   endif()

lib/libc++abi-new-delete.exp

+__ZdaPv
+__ZdlPv
+__ZdlPvRKSt9nothrow_t
+__Znam
+__ZdaPvRKSt9nothrow_t
+__Znwm
+__ZnwmRKSt9nothrow_t
+__ZnamRKSt9nothrow_t

lib/libc++abi2.exp

 __ZNSt10bad_typeidD0Ev
 __ZNSt10bad_typeidD2Ev
 __ZNSt13bad_exceptionD0Ev
 __ZNSt13bad_exceptionD2Ev
 __ZNSt20bad_array_new_lengthC2Ev
 __ZNSt20bad_array_new_lengthD0Ev
 __ZNSt20bad_array_new_lengthD2Ev
 __ZSt10unexpectedv
-__ZdaPv
-__ZdlPv
-__ZdlPvRKSt9nothrow_t
-__Znam
-__ZdaPvRKSt9nothrow_t
-__Znwm
-__ZnwmRKSt9nothrow_t
-__ZnamRKSt9nothrow_t
 __ZTISt10bad_typeid
 __ZTISt8bad_cast
 ___cxa_bad_typeid
 ___cxa_bad_cast
 __ZTISt9exception
 __ZTISt9type_info
 __ZTISt20bad_array_new_length