Re: [Boost-users] [preprocessor] Undeclared identifier BOOST_PP_IIF_0 under Clang only

Subject: Re: [Boost-users] [preprocessor] Undeclared identifier BOOST_PP_IIF_0 under Clang only
From: Pierre Talbot (ptalbot_at_[hidden])
Date: 2014-04-03 15:38:12

On 04/03/2014 05:31 PM, Edward Diener wrote:
> On 4/2/2014 3:48 PM, Pierre Talbot wrote:
>> Hi,
>>
>> I defined a macro using Boost.Preprocessor that compiles and works fine
>> under gcc but fails to compile under Clang. The macro is defined here:
>> https://github.com/ptal/Boost.Expected/blob/master/include/boost/functional/do_yield.hpp 
>>
>
> As a quick shot, without actual testing, define BOOST_PP_VARIADICS to 1.
It worked, thanks, but the problem is that it won't work if the user has 
previously included preprocessor without having defined this macro. 
Maybe it should be defined by default if the language version is C++11?
>
>>
>>
>> And the error message follows this message, the file using the macro is
>> https://github.com/ptal/Boost.Expected/blob/master/example/monadic_calculator/monadic_calculator.cpp 
>>
>>
>>
>> Thanks for any helps,
>> Pierre Talbot
>>
>> Boost.Expected/example/monadic_calculator$ b2
>> ...patience...
>> ...found 1246 targets...
>> ...updating 2 targets...
>> clang-linux.compile.c++.without-pth
>> bin/clang-linux-3.5.0/debug/monadic_calculator.o
>> monadic_calculator.cpp:141:15: error: use of undeclared identifier
>> 'BOOST_PP_IIF_0'
>>      etokens = DO(
>>                ^
>> ../../include/boost/functional/do_yield.hpp:100:17: note: expanded from
>> macro 'DO'
>> #define DO(...) DO_SEQ(BOOST_PP_VARIADIC_TO_SEQ(__VA_ARGS__))
>>                  ^
>> ../../include/boost/functional/do_yield.hpp:97:3: note: expanded from
>> macro 'DO_SEQ'
>>    BOOST_PP_SEQ_FOR_EACH_I(DO_ELEM, seq, seq) \
>>    ^
>> /usr/local/boost_1_55_0/boost/preprocessor/seq/for_each_i.hpp:27:55:
>> note: expanded from macro 'BOOST_PP_SEQ_FOR_EACH_I'
>> #    define BOOST_PP_SEQ_FOR_EACH_I(macro, data, seq)
>> BOOST_PP_FOR((macro, data, seq (nil), 0), BOOST_PP_SEQ_FOR_EACH_I_P,
>> BOOST_PP_SEQ_FOR_EACH_I_O, BOOST_PP_SEQ_FOR_EACH_I_M)
>>                                                        ^
>> /usr/local/boost_1_55_0/boost/preprocessor/repetition/for.hpp:27:23:
>> note: expanded from macro 'BOOST_PP_FOR'
>> # define BOOST_PP_FOR BOOST_PP_CAT(BOOST_PP_FOR_,
>> BOOST_PP_AUTO_REC(BOOST_PP_FOR_P, 256))
>>                        ^
>> /usr/local/boost_1_55_0/boost/preprocessor/cat.hpp:22:32: note: expanded
>> from macro 'BOOST_PP_CAT'
>> #    define BOOST_PP_CAT(a, b) BOOST_PP_CAT_I(a, b)
>>                                 ^
>> /usr/local/boost_1_55_0/boost/preprocessor/cat.hpp:29:34: note: expanded
>> from macro 'BOOST_PP_CAT_I'
>> #    define BOOST_PP_CAT_I(a, b) a ## b
>>                                   ^
>> <scratch space>:130:1: note: expanded from here
>> BOOST_PP_FOR_1
>> ^
>> /usr/local/boost_1_55_0/boost/preprocessor/repetition/detail/for.hpp:22:37: 
>>
>> note: expanded from macro 'BOOST_PP_FOR_1'
>> # define BOOST_PP_FOR_1(s, p, o, m) BOOST_PP_FOR_1_C(BOOST_PP_BOOL(p(2,
>> s)), s, p, o, m)
>>                                      ^
>> /usr/local/boost_1_55_0/boost/preprocessor/repetition/detail/for.hpp:279:42: 
>>
>> note: expanded from macro 'BOOST_PP_FOR_1_C'
>> # define BOOST_PP_FOR_1_C(c, s, p, o, m) BOOST_PP_IIF(c, m,
>> BOOST_PP_TUPLE_EAT_2)(2, s) BOOST_PP_IIF(c, BOOST_PP_FOR_2,
>> BOOST_PP_TUPLE_EAT_4)(BOOST_PP_EXPR_IIF(c, o)(2, s), p, o, m)
>>                                           ^
>> /usr/local/boost_1_55_0/boost/preprocessor/control/iif.hpp:18:37: note:
>> expanded from macro 'BOOST_PP_IIF'
>> #    define BOOST_PP_IIF(bit, t, f) BOOST_PP_IIF_I(bit, t, f)
>>                                      ^
>> /usr/local/boost_1_55_0/boost/preprocessor/control/iif.hpp:25:39: note:
>> expanded from macro 'BOOST_PP_IIF_I'
>> #    define BOOST_PP_IIF_I(bit, t, f) BOOST_PP_IIF_ ## bit(t, f)
>>                                        ^
>> <scratch space>:136:1: note: expanded from here
>> BOOST_PP_IIF_0
>> ^
>
>
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