id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
11014	Inconsistent use of BOOST_PP_VARIADICS_MSVC	Matthew Collett <m_collett@…>	No-Maintainer	"Clang generates multiple warnings of the form
{{{
'BOOST_PP_VARIADICS_MSVC' is not defined, evaluates to 0
}}}

In `config/config.hpp`, `BOOST_PP_VARIADICS_MSVC` is either set to 1 or left undefined, but the following files test the //value// of `BOOST_PP_VARIADICS_MSVC`, triggering the above warning when the macro is undefined:
{{{
seq/detail/binary_transform.hpp
tuple/elem.hpp
variadic/elem.hpp
array/detail/get_data.hpp
punctuation/is_begin_parens.hpp
punctuation/detail/is_begin_parens.hpp
facilities/is_empty_variadic.hpp
facilities/detail/is_empty.hpp
tuple/detail/is_single_return.hpp
variadic/detail/is_single_return.hpp
tuple/rem.hpp
tuple/reverse.hpp
tuple/size.hpp
variadic/size.hpp
list/to_array.hpp
tuple/to_array.hpp
variadic/to_array.hpp
tuple/to_list.hpp
tuple/to_seq.hpp
test/tuple.cxx
}}}
Suggested fix: change all the above to use `#ifdef` or `defined` to test the //existence// of `BOOST_PP_VARIADICS_MSVC` instead of the value.  (A global replacement of `BOOST_PP_VARIADICS_MSVC` by `defined(BOOST_PP_VARIADICS_MSVC)` would be effective, if not elegant.)

Alternate fix: change `config/config.hpp` so that `BOOST_PP_VARIADICS_MSVC` is either set to 1 or set to 0.
In that case, the following files, which do currently test the existence of `BOOST_PP_VARIADICS_MSVC` (using `defined`), will need to be changed to test the value:
{{{
test/facilities.cxx
test/isempty_variadic_standard_failure.cxx
test/isempty_variadic_standard_failure2.cxx
test/isempty.cxx
}}}"	Bugs	closed	To Be Determined	preprocessor	Boost 1.57.0	Cosmetic	fixed