[runtimes] Prefer -fvisibility-global-new-delete=force-hidden (#84917)

27ce26b added the new option
-fvisibility-global-new-delete=, where -fvisibility-global-new-delete=force-hidden
is equivalent to the old option -fvisibility-global-new-delete-hidden.
At the same time, the old option was deprecated.

Test for and use the new option form first; if unsupported, try 
using the old form.

This avoids warnings in the MinGW builds, if built with Clang 18 or
newer.

Author: mstorsjo

libcxx/src/CMakeLists.txt

@@ -301,7 +301,10 @@ if (LIBCXX_ENABLE_STATIC)
     # 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)
+      append_flags_if_supported(CXX_STATIC_LIBRARY_FLAGS -fvisibility-global-new-delete=force-hidden)
+      if (NOT CXX_SUPPORTS_FVISIBILITY_GLOBAL_NEW_DELETE_EQ_FORCE_HIDDEN_FLAG)
+        append_flags_if_supported(CXX_STATIC_LIBRARY_FLAGS -fvisibility-global-new-delete-hidden)
+      endif()
     endif()
     target_compile_options(cxx_static PRIVATE ${CXX_STATIC_LIBRARY_FLAGS})
     # _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS can be defined in __config_site

libcxxabi/src/CMakeLists.txt

@@ -268,7 +268,10 @@ if(LIBCXXABI_HERMETIC_STATIC_LIBRARY)
   # then its code shouldn't declare them with hidden visibility.  They might
   # actually be provided by a shared library at link time.
   if (LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS)
-    target_add_compile_flags_if_supported(cxxabi_static_objects PRIVATE -fvisibility-global-new-delete-hidden)
+    target_add_compile_flags_if_supported(cxxabi_static_objects PRIVATE -fvisibility-global-new-delete=force-hidden)
+    if (NOT CXX_SUPPORTS_FVISIBILITY_GLOBAL_NEW_DELETE_EQ_FORCE_HIDDEN_FLAG)
+      target_add_compile_flags_if_supported(cxxabi_static_objects PRIVATE -fvisibility-global-new-delete-hidden)
+    endif()
   endif()
   # _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS can be defined in libcxx's
   # __config_site too. Define it in the same way here, to avoid redefinition

libunwind/src/CMakeLists.txt

@@ -201,7 +201,10 @@ set_target_properties(unwind_static_objects
 
 if(LIBUNWIND_HIDE_SYMBOLS)
   target_add_compile_flags_if_supported(unwind_static_objects PRIVATE -fvisibility=hidden)
-  target_add_compile_flags_if_supported(unwind_static_objects PRIVATE -fvisibility-global-new-delete-hidden)
+  target_add_compile_flags_if_supported(unwind_static_objects PRIVATE -fvisibility-global-new-delete=force-hidden)
+  if (NOT CXX_SUPPORTS_FVISIBILITY_GLOBAL_NEW_DELETE_EQ_FORCE_HIDDEN_FLAG)
+    target_add_compile_flags_if_supported(unwind_static_objects PRIVATE -fvisibility-global-new-delete-hidden)
+  endif()
   target_compile_definitions(unwind_static_objects PRIVATE _LIBUNWIND_HIDE_SYMBOLS)
 endif()