If it sheds light... the original issue was that the static const float was
being defined and initialized with a value in the header, which worked with
GCC because of a GCC-extension. This, however failed with MSVC (or gcc
running in -pedantic mode apparently).
So the declaration/init was split between the .h and .cc file, which fixed
that problem, but obviously introduced this new issue.
I agree replacing the macro with "const" in the header and leaving the
initialization in the .cc file would work.
Geof
On Tue, Mar 7, 2017 at 2:26 PM, Martin Braun <martin.br...@ettus.com> wrote:
> Agree with Michael, especially since we don't allow C++11 features yet.
>
> Martin
>
> On 6 Mar 2017 7:41 am, "Michael Dickens" <michael.dick...@ettus.com>
> wrote:
>
>> I have a MacPorts ticket requesting that I enable CTRLPORT, which
>> requires Thrift, which was recently updated to 0.10.0 in MacPorts -- so
>> I thought it worth a try again to see if it works.
>>
>> Thrift requires C++11 for building, which means that "gnuradio
>> +ctrlport" will also require C++11. Easy enough, or so I thought, by
>> forcing CMake to use C++11 via using the right compiler and adding
>> "-DCMAKE_CXX_STANDARD=11" as a commandline argument.
>>
>> This combination works well until it reaches gr-fec, which errors out
>> due to a BOOST_CONSTEXPR_OR_CONST declaration that's valid C++ when it
>> is "const" ... but the C++ code isn't valid for a "constexpr", which
>> requires that the variable value be defined in the declaration.
>>
>> gr-fec/include/gnuradio/fec/polar_decoder_common.h:70
>> {{{
>> private:
>> static BOOST_CONSTEXPR_OR_CONST float D_LLR_FACTOR;
>> }}}
>>
>> gr-fec/lib/polar_decoder_common.cc:37
>> {{{
>> const float polar_decoder_common::D_LLR_FACTOR = -2.19722458f;
>> }}}
>>
>> Looks like D_LLR_FACTOR was correctly defined to work with the
>> "constexpr" or "const" version of BOOST_CONSTEXPR_OR_CONST in <
>> https://github.com/gnuradio/gnuradio/commit/a1cf11937665392b
>> cfa223a5095ff903eb44c69b
>> > by Jaroslav Škarvada, and then broken in <
>> https://github.com/gnuradio/gnuradio/commit/a981e6a18c4f28cc
>> 6058fef4167c01ad3dc7d58a
>> > by Josh Blum.
>>
>> In my searching, the code above is the -only- place where a "constexpr"
>> is potentially used. Thus, can we please just get rid of it and use
>> "const" instead? Why the need for a constexpr here and no other place?
>>
>> One can work around this issue by defining BOOST_NO_CXX11_CONSTEXPR, but
>> the code should be able to build without this workaround.
>>
>> Thoughts? Comments? - MLD
>>
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>
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