:: Re: [Libbitcoin] Libbitcoin and Qt
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Autor: Eric Voskuil
Datum:  
To: Bedeho Mender
CC: libbitcoin@lists.dyne.org
Betreff: Re: [Libbitcoin] Libbitcoin and Qt
This isn't a problem with cross-compiler linking (or a regression), it's
simply the result of the fact that we don't yet have the exports/imports
properly/fully defined for DLL linkage (not yet supported).

The errors are the result of BC_API getting defined to
__declspec(dllimport). You just need to define BC_STATIC. See define.hpp.

e

On 03/24/2015 01:16 AM, Eric Voskuil wrote:
> Hi Bedeho,
>
> I suspect the errors are the result of a change I made today in master.
> I'll look into it.
>
> The define warning pertains to your project. All libbitcoin VS. projects
> declare Windows XP SP2 as the build target:
>
> _WIN32_WINNT=0x0600
>
> If you currently have no reason to do otherwise I'd recommend you do the
> same in your project.
>
> e
>
> On 03/24/2015 12:01 AM, Bedeho Mender wrote:
>> Hi Eric,
>>
>> Giving the new headers a try.
>>
>> As before, built libbitcoin with MSVC Nov 2013 CTP, and then I have an
>> example Qt project which uses the vanilla MSVC2013.
>>
>> I get different build errors this time, and fewer of them. As one would
>> expect, nothing related to constexpr.
>>
>> There are basically headers which cause problems, as seen by these errors
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(74) :
>> error C2375: 'libbitcoin::operator >' : redefinition; different linkage
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(57) :
>> see declaration of 'libbitcoin::operator >'
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(76) :
>> error C2375: 'libbitcoin::operator <=' : redefinition; different linkage
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(59) :
>> see declaration of 'libbitcoin::operator <='
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(78) :
>> error C2375: 'libbitcoin::operator <<' : redefinition; different linkage
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(61) :
>> see declaration of 'libbitcoin::operator <<'
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(80) :
>> error C2375: 'libbitcoin::operator /' : redefinition; different linkage
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(63) :
>> see declaration of 'libbitcoin::operator /'
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(82) :
>> error C2375: 'libbitcoin::operator +' : redefinition; different linkage
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(65) :
>> see declaration of 'libbitcoin::operator +'
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(84) :
>> error C2375: 'libbitcoin::operator ==' : redefinition; different linkage
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash_number.hpp(67) :
>> see declaration of 'libbitcoin::operator =='
>>
>> Please define _WIN32_WINNT or _WIN32_WINDOWS appropriately. For example:
>>
>> - add -D_WIN32_WINNT=0x0501 to the compiler command line; or
>>
>> - add _WIN32_WINNT=0x0501 to your project's Preprocessor Definitions.
>>
>> Assuming _WIN32_WINNT=0x0501 (i.e. Windows XP target).
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/utility/binary.hpp(79)
>> : error C2375: 'libbitcoin::operator ==' : redefinition; different linkage
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/utility/binary.hpp(64)
>> : see declaration of 'libbitcoin::operator =='
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/utility/binary.hpp(84)
>> : error C2375: 'libbitcoin::operator >>' : redefinition; different linkage
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/utility/binary.hpp(66)
>> : see declaration of 'libbitcoin::operator >>'
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/utility/binary.hpp(86)
>> : error C2375: 'libbitcoin::operator <<' : redefinition; different linkage
>>
>> C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/utility/binary.hpp(68)
>> : see declaration of 'libbitcoin::operator <<'
>>
>> This is what I'm working with: https://github.com/bedeho/QtLibbitcoin
>>
>> best
>> Bedeho
>>
>>
>> On 23 March 2015 at 22:07, Eric Voskuil <eric@???
>> <mailto:eric@voskuil.org>> wrote:
>>
>>     Regarding the /Zc:threadSafeInit option, this was added later, in the
>>     June "VS14" CTP (now VS2015 in CTP 6), so I'm leaving it as-is.

>>
>>     e

>>
>>
>>     On 03/23/2015 01:49 PM, Eric Voskuil wrote:
>>     > I've updated all libbitcoin repos so that there is no code in
>>     published
>>     > headers requiring the VC++ CTP compiler (generally C++11 stuff, mostly
>>     > constexpr).
>>     >
>>     > I've done the same in all test projects, which I've also changed
>>     to not
>>     > use the CTP compiler and instead use VC++12. This provides a
>>     convenient
>>     > means to ensure that the CTP requirement doesn't creep into the
>>     headers
>>     > or break in another manner. It also provides an example of how to link
>>     > to the main libraries (built with the CTP compiler) using the RTM
>>     compiler.

>>     >
>>     > There is a small additional runtime library that augments the CRT when
>>     > linking with VC12. This is automatically incorporated, although I may
>>     > try and get rid of that requirement by using " /Zc:threadSafeInit" as
>>     > described here:

>>     >

>>     >
>>     http://blogs.msdn.com/b/vcblog/archive/2014/06/03/visual-studio-14-ctp.aspx

>>     >
>>     > The changes are accomplished using three new libbitcoin macros
>>     > (BC_CONSTREXPR, BC_CONSTFUNC and BC_NOEXCEPT) so that non-MSVC builds
>>     > are unaffected. These should be used in all published headers and
>>     tests.

>>     >
>>     > e

>>     >
>>     > On 03/19/2015 02:39 PM, Eric Voskuil wrote:
>>     >> It may not be too difficult to remove from headers. Templates may
>>     >> present problems beyond the use of constexpr. I'd be happy to
>>     review a
>>     >> pull request.

>>     >>
>>     >> e

>>     >>
>>     >> On 03/19/2015 02:07 PM, Bedeho Mender wrote:
>>     >>> Hi Eric,

>>     >>>
>>     >>> Ive been talking to some Qt developers, and it appears that you do
>>     >>> indeed have to rebuild Qt with a newer MSVC version, however, it
>>     turns
>>     >>> out that this is likely not possible with the present build
>>     system on
>>     >>> Windows with these new versions of MSVC (for reasons was not given).

>>     >>>
>>     >>> How difficult would it be to have a version of libbitcoin where
>>     the CTP
>>     >>> 2013 features were taken out, so that libbitcoin could be used
>>     with the
>>     >>> latest full release of MSVC 2013? That is, how prevalent is the
>>     usage of
>>     >>> C++11 features which only are implemented in the CTP? e.g.
>>     constexpr.

>>     >>>
>>     >>> I would be happy to sponsor this dev work depending on how
>>     involved it
>>     >>> would be, and that would allow people to use libbitcoin with Qt
>>     -  which
>>     >>> I think a lot of people will likely want to do, given that Qt is the
>>     >>> most popular C++ framework out there.

>>     >>>
>>     >>> best
>>     >>>  bedeho

>>     >>>

>>     >>>

>>     >>>
>>     >>> On 17 March 2015 at 20:52, Eric Voskuil <eric@???
>>     <mailto:eric@voskuil.org>
>>     >>> <mailto:eric@voskuil.org <mailto:eric@voskuil.org>>> wrote:

>>     >>>
>>     >>>     Ah yes, that's unfortunate. Now I remember I looked at QT a
>>     while back
>>     >>>     and determined I would need to compile QT to make it work. I
>>     decided to
>>     >>>     wait for time to resolve the issue :/

>>     >>>
>>     >>>     e

>>     >>>
>>     >>>     On 03/17/2015 06:27 AM, Bedeho Mender wrote:
>>     >>>     > Hi Eric, thanks for the quick response!

>>     >>>     >
>>     >>>     > It doesn't appear so to me, but perhaps I am
>>     misunderstanding the
>>     >>>     problem.

>>     >>>     >
>>     >>>     > When I make a minimal Qt project
>>     >>>     > (https://github.com/bedeho/QtLibbitcoin/blob/master/main.cpp)
>>     >>>     which uses
>>     >>>     > MSVC2013, then if I just
>>     >>>     > include the libbitcoin header #include
>>     <bitcoin/bitcoin.hpp>, then
>>     >>>     I get
>>     >>>     > lots of compile errors.

>>     >>>     >
>>     >>>     > The errors seem to be associated with certain c++11
>>     features which
>>     >>>     > msvc2013 does
>>     >>>     > not support fully. Here is the first error I get

>>     >>>     >

>>     >>>     >
>>     C:\libbitcoin\libbitcoin\include\bitcoin/bitcoin/math/hash.hpp(31) :
>>     >>>     > error C2146: syntax error : missing ';' before identifier
>>     'size_t'

>>     >>>     >
>>     >>>     > Which references line 31 in hash.hpp:

>>     >>>     >
>>     >>>     > constexpr size_t short_hash_size = 20;

>>     >>>     >
>>     >>>     > In this case, the problem seems to be that constexpr is a
>>     new feature
>>     >>>     > which msvc2013 does not support, from what I could
>>     understand by
>>     >>>     > reading up, and that CTP_Nov2013 was required for this
>>     reason. For
>>     >>>     > example, the release notes on this CTP explicitly mentions
>>     constexpr
>>     >>>     > support
>>     >>>     (http://www.microsoft.com/en-us/download/details.aspx?id=41151):
>>     >>>     > "constexpr (except for constructors)"

>>     >>>     >
>>     >>>     > Am I on the wrong track here? If not, getting Qt to work
>>     with CTP
>>     >>>     > is necessary to for using Libbitcon with Qt.

>>     >>>     >
>>     >>>     > bedeho

>>     >>>     >

>>     >>>     >
>>     >>>     > On 16 March 2015 at 22:48, Eric Voskuil <eric@???
>>     <mailto:eric@voskuil.org>
>>     >>>     <mailto:eric@voskuil.org <mailto:eric@voskuil.org>>
>>     >>>     > <mailto:eric@voskuil.org <mailto:eric@voskuil.org>
>>     <mailto:eric@voskuil.org <mailto:eric@voskuil.org>>>> wrote:

>>     >>>     >
>>     >>>     >     You can link to the libbitcoin VC++ libs using the
>>     basic v120
>>     >>>     >     compiler, they are compatible.

>>     >>>     >
>>     >>>     >     e

>>     >>>     >

>>     >>>     >
>>     >>>     >     > On Mar 16, 2015, at 8:58 AM, Bedeho Mender
>>     >>>     >     <bedeho.mender@???
>>     <mailto:bedeho.mender@gmail.com> <mailto:bedeho.mender@gmail.com
>>     <mailto:bedeho.mender@gmail.com>>
>>     >>>     <mailto:bedeho.mender@gmail.com
>>     <mailto:bedeho.mender@gmail.com> <mailto:bedeho.mender@gmail.com
>>     <mailto:bedeho.mender@gmail.com>>>>
>>     >>>     wrote:

>>     >>>     >     >
>>     >>>     >     > I have built libbitcoin with msvc using the compiler
>>     Microsoft
>>     >>>     >     Visual C++ Compiler Nov 2013 CTP.

>>     >>>     >     >
>>     >>>     >     > I am trying to use libbitcoin with a Qt project
>>     running in
>>     >>>     >     QtCreator, however it seems this is not easy to do,
>>     that is get Qt
>>     >>>     >     to get with the CTP.

>>     >>>     >     >
>>     >>>     >     > Does anyone have any advice on this?

>>     >>>     >     >
>>     >>>     >     > best
>>     >>>     >     >  Bedeho

>>     >>>

>>     >>>

>>     >>

>>     >

>>
>>
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>>
>>
>