* c-common.c (flag_ms_extensions): Move from c++ front end.
        * c-common.h (flag_ms_extensions): Declare.
        * c-decl.c (c_decode_option): Add -fms-extensions.
        (grokfield): Don't accept anonymous structures in ISO C mode;
        accept only unnamed anonymous structures in GNU C mode; accept
        Plan 9 extensions in MS mode.
        * c-parse.in (SAVE_EXT_FLAGS, RESTORE_EXT_FLAGS): Rename from
        SAVE/RESTORE_WARN_FLAGS; add flag_iso frobbing; update all callers.
        (extension): Clear flag_iso.
        * doc/invoke.texi (C Dialect Options): Add -fms-extensions.

        * cp-tree.h, decl2.c (flag_ms_extensions): Move to c-common.

        * g++.dg/ext/anon-struct1.C: New.
        * g++.dg/ext/anon-struct2.C: New.
        * g++.dg/ext/anon-struct3.C: New.
        * gcc.dg/anon-struct-1.c: New.
        * gcc.dg/anon-struct-2.c: New.
        * gcc.dg/anon-struct-3.c: New.
        * gcc.dg/20011008-1.c: Adjust warning text.
        * gcc.dg/20020527-1.c: Add -fms-extensions.

From-SVN: r54670