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Subject: Re: [boost] [wave] preprocessor directives in output
From: Thomas Heller (thom.heller_at_[hidden])
Date: 2014-01-21 02:38:20


On 01/21/2014 08:17 AM, Fletcher, John P wrote:
> How about making macros for #if, #else, #endif
>
> BOOST_KEEP_UNTIL_WAVE_OUTPUT(if) -> #if
>
> Then tell Wave not to translate it and translate it in the output.

the problem is that pp macros can't be expanded to pp directives.

>
> John
> ________________________________________
> From: Boost [boost-bounces_at_[hidden]] on behalf of Joel de Guzman [djowel_at_[hidden]]
> Sent: 21 January 2014 06:29
> To: boost_at_[hidden]
> Subject: Re: [boost] [wave] preprocessor directives in output
>
> On 1/21/14, 9:46 AM, Eric Niebler wrote:
>> I'm looking at automating the regeneration of Fusion's preprocess
>> headers with the wave tool. Currently, it's impossible because of stuff
>> like this (from container\vector\vector.hpp):
>>
>> #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
>> vector(vector&& rhs)
>> : vec(std::forward<vector_n>(rhs.vec)) {}
>> #endif
>>
>> When the wave driver is run, either BOOST_NO_CXX11_RVALUE_REFERENCES is
>> defined, in which case the block of code gets left out, or else it
>> isn't, in which case the block of code is left in. Both are wrong. What
>> should happen is that the #if and #else directives should be present in
>> wave's output.
>>
>> I can keep wave from expanding certain named macros with the -N switch,
>> but there doesn't seem to be a way to selectively keep wave from
>> evaluating #if/#else directives. Or is there?
>
> I asked Hartmut this same question before. IIRC, it's an issue that has no
> workaround (or fix) yet. I hope I am wrong.
>
> Regards,
> --
> Joel de Guzman
> http://www.ciere.com
> http://boost-spirit.com
> http://www.cycfi.com/
>
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