* c-common.h (has_c_linkage): New interface.
	* c-cppbuiltin.c: Include target.h.
	(c_cpp_builtins): Define __PRAGMA_REDEFINE_EXTNAME and
	__PRAGMA_EXTERN_PREFIX when appropriate.
	* c-pragma.c: Include target.h.
	Document clarified semantics of symbol-renaming #pragmas.
	(handle_pragma_redefine_extname, handle_pragma_extern_prefix)
	(maybe_apply_renaming_pragma): Rewrite according to clarified
	semantics.  Always recognize, but do not necessarily execute.
	(init_pragma): Unconditionally register symbol-renaming pragmas.
	* system.h: Poison HANDLE_PRAGMA_REDEFINE_EXTNAME
	and HANDLE_PRAGMA_EXTERN_PREFIX.
	* target.h (struct gcc_target): Add handle_pragma_redefine_extname
	and handle_pragma_extern_prefix flags.
	* target-def.h: Add defaults for TARGET_HANDLE_PRAGMA_REDEFINE_EXTNAME
	and TARGET_HANDLE_PRAGMA_EXTERN_PREFIX.
	* Makefile.in (c-pragma.o, c-cppbuiltin.o): Update dependencies.
	* config/sol2.h: Define TARGET_HANDLE_PRAGMA_REDEFINE_EXTNAME,
	not HANDLE_PRAGMA_REDEFINE_EXTNAME.
	(TARGET_OS_CPP_BUILTINS): No need to define __PRAGMA_REDEFINE_EXTNAME.
	(TRANSFER_FROM_TRAMPOLINE): Prototype mprotect.
	* config/alpha/osf.h: Define TARGET_HANDLE_PRAGMA_EXTERN_PREFIX,
	not HANDLE_PRAGMA_EXTERN_PREFIX.
	(TARGET_OS_CPP_BUILTINS): No need to define __PRAGMA_EXTERN_PREFIX.
	* doc/extend.texi (Solaris Pragmas, Tru64 Pragmas): Combine
	into one section "Symbol-Renaming Pragmas"; clarify; document
	adjusted semantics.

	* builtins.c (expand_builtin): Do not issue error for a builtin
	with no special case code and no DECL_ASSEMBLER_NAME; just do the
	library call.
	* c-decl.c (builtin_function): Don't call make_decl_rtl.
	* c-objc-common.c (has_c_linkage): Stub implementation.
	* cgraphunit.c (cgraph_expand_function)
	(cgraph_remove_unreachable_nodes): Don't clear DECL_ARGUMENTS.

cp:
	* cp-lang.c (has_c_linkage): Implement.

	* cp-tree.h (set_mangled_name_for_decl): Don't prototype.
	* decl.c (duplicate_decls): Use COPY_DECL_RTL.
	(builtin_function_1): Don't call make_decl_rtl.
	(build_cp_library_fn): Don't call set_mangled_name_for_decl.
	(grokvardecl): Don't call mangle_decl.
	* except.c (nothrow_libfn_p): Look at DECL_NAME, not
	DECL_ASSEMBLER_NAME.
	* method.c (set_mangled_name_for_decl): Delete.
	* name-lookup.c (pushdecl): When a local extern shadows a
	file-scope declaration of the same object, give both DECLs the
	same DECL_UID.
	* typeck.c (cxx_mark_addressable): Don't set TREE_ADDRESSABLE
	on DECL_ASSEMBLER_NAME.

testsuite:
	* g++.dg/expr/enum1.C, g++.dg/opt/const3.C: Declare abort with
	extern "C".
	* g++.dg/other/pragma-re-1.C: Add comments.

From-SVN: r83405