PR opt/4330
* langhooks.h (lang_hooks.decls.warn_unused_global): New.
* toplev.c (check_global_declarations): Use it.
* langhooks-def.h (lhd_warn_unused_global_decl): Declare.
(LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): New.
(LANG_HOOKS_DECLS): Add it.
* langhooks.c (lhd_warn_unused_global_decl): New.
* c-decl.c (LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): New.
* c-objc-common.c (c_warn_unused_global_decl): New.
* c-tree.h (c_warn_unused_global_decl): Declare.
* objc/objc-lang.c (LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): New.
* cp-lang.c (cxx_warn_unused_global_decl): New.
(LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL): New.
* g++.dg/warn/Wunused-2.C: New.
* gcc.dg/unused-4.c: New.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@51818
138bc75d-0d04-0410-961f-
82ee72b054a4