This implements __VA_OPT__, a new preprocessor feature added in C++2A.
The paper can be found here:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0306r4.html
gcc/ChangeLog
* doc/cpp.texi (Variadic Macros): Document __VA_OPT__.
gcc/testsuite/ChangeLog
* c-c++-common/cpp/va-opt-pedantic.c: New file.
* c-c++-common/cpp/va-opt.c: New file.
* c-c++-common/cpp/va-opt-error.c: New file.
libcpp/ChangeLog
* pch.c (cpp_read_state): Set n__VA_OPT__.
* macro.c (vaopt_state): New class.
(_cpp_arguments_ok): Check va_opt flag.
(replace_args, create_iso_definition): Use vaopt_state.
* lex.c (lex_identifier_intern): Possibly issue errors for
__VA_OPT__.
(lex_identifier): Likewise.
(maybe_va_opt_error): New function.
* internal.h (struct lexer_state) <va_args_ok>: Update comment.
(struct spec_nodes) <n__VA_OPT__>: New field.
* init.c (struct lang_flags) <va_opt>: New field.
(lang_defaults): Add entries for C++2A. Update all entries for
va_opt.
(cpp_set_lang): Initialize va_opt.
* include/cpplib.h (struct cpp_options) <va_opt>: New field.
* identifiers.c (_cpp_init_hashtable): Initialize n__VA_OPT__.
From-SVN: r254707
fb771b9dad