Problem using Vc with CMake 3.0 and kf5

[Alex Merry]

On Saturday 23 May 2015 11:51:55 Boudewijn Rempt wrote:
> Sorry for the extensive cross-posting in advance, please when replying, do
> a reply-all.
> 
> Just so everyone is on the same page: Vc is a template library that makes
> it easy to build vectorized code using a single source file. Krita uses Vc
> to optimize blending colors, creating masks and much more. Krita uses the
> most recent Vc release, 0.7.4:
> http://code.compeng.uni-frankfurt.de/news/27
> 
> We're currently porting Krita to Qt5 and KF5 and the way KF5 and Vc handle
> include directories is a big roadblock for us:
> https://git.reviewboard.kde.org/r/123179/ .
> 
> In a nutshell: Vc builds many different object files from single cpp file.
> It does this by creating a custom command for each target vectorization
> extension. To do that, it needs to access the contents of
> INCLUDE_DIRECTORIES, like this (in VcMacros.cmake:
> http://code.compeng.uni-frankfurt.de/projects/vc/repository/entry/cmake/VcMa
> cros.cmake?rev=0.7)
> 
>     get_directory_property(_inc INCLUDE_DIRECTORIES)
>     foreach(_i ${_inc})
>        list(APPEND _flags "-I${_i}")
>     endforeach()
> 
> In the end the command is generated like this:
> 
>           add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${_out}
>              COMMAND ${CMAKE_CXX_COMPILER} ${_flags} ${_extra_flags}
>              -DVC_IMPL=${_impl}
>              ${_outfile_flag}${_out}
> ${CMAKE_CURRENT_SOURCE_DIR}/${_vc_compile_src}
>              MAIN_DEPENDENCY ${CMAKE_CURRENT_SOURCE_DIR}/${_vc_compile_src}
>              IMPLICIT_DEPENDS CXX
> ${CMAKE_CURRENT_SOURCE_DIR}/${_vc_compile_src}
>              COMMENT "Building CXX object ${_out}"
>              WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
>              VERBATIM
>              )
> KF5 uses cmake generator expressions to derive the include
> directories from the target_link_libraries lines. This means that when we
> try to build our per-extensions object files we get this:
> 
> 
> 
>      [  0%] Building CXX object
> KoOptimizedCompositeOpFactoryPerArch_AVX.cpp.o
>      cd /home/boud/kde/build/calligra/libs/pigment && /usr/bin/c++
> -std=c++0x -fno-exceptions -Wall -Wextra -Wcast-align -Wchar-subscripts
> -Wformat-security -Wno-long-long -Wpointer-arith -Wundef
> -Wnon-virtual-dtor -Woverloaded-virtual -Werror=return-type
> -D__GNUC_UBUNTU_VERSION__=0xf040a -Wabi -fabi-version=0 -ffp-contract=fast
> -mtune=core2 -fPIC -I/home/boud/kde/src/calligra/interfaces
> -I/home/boud/kde/build/calligra -I/home/boud/kde/src/calligra
> -I/home/boud/kde/src/calligra/libs/version
> -I/home/boud/kde/build/calligra/libs/version
> -I/home/boud/kde/src/calligra/libs/koplugin
> -I/home/boud/kde/src/calligra/libs/version
> -I/home/boud/kde/build/calligra/libs/version
> -I/home/boud/kde/src/calligra/libs/pigment
> -I/home/boud/kde/src/calligra/libs/pigment/compositeops
> -I/home/boud/kde/src/calligra/libs/pigment/resources -I/usr/include
> -I/usr/include -I/usr/include/OpenEXR -I/usr/include -mavx -DVC_IMPL=AVX
> -c -oKoOptimizedCompositeOpFactoryPerArch_AVX.cpp.o
> /home/boud/kde/src/calligra/libs/pigment/compositeops/KoOptimizedCompositeOp
> FactoryPerArch.cpp
> 
> /home/boud/kde/src/calligra/libs/pigment/compositeops/KoOptimizedCompositeOp
> FactoryPerArch.cpp:22:19: fatal error: QString: No such file or directory
>       #include <QString>
>                         ^
>      compilation terminated.
>      libs/pigment/CMakeFiles/pigmentcms.dir/build.make:72: recipe for
> target 'libs/pigment/KoOptimizedCompositeOpFactoryPerArch_AVX.cpp.o'
> failed
> 
> On other words, INCLUDE_DIRECTORIES is empty, there's no Qt5, no Kf5 to be
> found.
> 
> If we manually set include directories like this:
> 
> if (HAVE_VC)
>      message(".>>>>>>>>>>>>" ${KDE4_INCLUDES})
>      include_directories(${KDE4_INCLUDES} ${Qt5Core_INCLUDE_DIRS}
> ${Qt5Gui_INCLUDE_DIRS} ${Qt5Xml_INCLUDE_DIRS} ${PIGMENT_INCLUDES} 
> ${Boost_INCLUDE_DIR}) endif()
> 
> We end up with the entire include line for the contents of KDE4_INCLUDES
> ($<TARGET_PROPERTY:KF5::KDELibs4Support,INTERFACE_INCLUDE_DIRECTORIES>)
> expanded to a string with quotes around it:
> 
>     [  0%] Building CXX object
> KoOptimizedCompositeOpFactoryPerArch_AVX.cpp.o
>      cd /home/boud/kde/build/calligra/libs/pigment && /usr/bin/c++
> -std=c++0x -fno-exceptions -Wall -Wextra -Wcast-align -Wchar-subscripts
> -Wformat-security -Wno-long-long -Wpointer-arith -Wundef
> -Wnon-virtual-dtor -Woverloaded-virtual -Werror=return-type
> -D__GNUC_UBUNTU_VERSION__=0xf040a -Wabi -fabi-version=0 -ffp-contract=fast
> -mtune=core2 -fPIC -I/home/boud/kde/src/calligra/interfaces
> -I/home/boud/kde/build/calligra -I/home/boud/kde/src/calligra
> -I/home/boud/kde/src/calligra/libs/version
> -I/home/boud/kde/build/calligra/libs/version
> "-I/usr/include/KF5/KDELibs4Support;/usr/include/KF5/KDELibs4Support/KDE;/us
> r/include/KF5;/usr/include/x86_64-linux-gnu/qt5/;/usr/include/x86_64-linux-g
> nu/qt5/QtWidgets;/usr/include/x86_64-linux-gnu/qt5/;/usr/include/x86_64-linu
> x-gnu/qt5/QtGui;/usr/include/x86_64-linux-gnu/qt5/;/usr/include/x86_64-linux
> -gnu/qt5/QtCore;/usr/lib/x86_64-linux-gnu/qt5//mkspecs/linux-g++-64;/usr/inc
> lude/x86_64-linux-gnu/qt5/;/usr/include/x86_64-linux-gnu/qt5/QtDBus;/usr/inc
> lude/x86_64-linux-gnu/qt5/;/usr/include/x86_64-linux-gnu/qt5/QtPrintSupport;
> /usr/include/KF5/KCoreAddons;/usr/include/KF5;/usr/include/KF5/KCrash;/usr/i
> nclude/KF5;/usr/include/KF5/KWidgetsAddons;/usr/include/KF5;/usr/include/KF5
> /KConfigCore;/usr/include/KF5;/usr/include/KF5/KConfigWidgets;/usr/include/K
> F5;/usr/include/KF5/KCodecs;/usr/include/KF5;/usr/include/KF5/KConfigGui;/us
> r/include/KF5;/usr/include/x86_64-linux-gnu/qt5/;/usr/include/x86_64-linux-g
> nu/qt5/QtXml;/usr/include/KF5/KAuth;/usr/include/KF5;/usr/include/KF5/KIOCor
> e;
> /usr/include/KF5;/usr/include/KF5/KService;/usr/include/KF5;/usr/include/KF
> 5/KIOFileWidgets;/usr/include/KF5;/usr/include/KF5/KIOWidgets;/usr/include/K
> F5;/usr/include/KF5/KJobWidgets;/usr/include/KF5;/usr/include/x86_64-linux-g
> nu/qt5/;/usr/include/x86_64-linux-gnu/qt5/QtNetwork;/usr/include/KF5/KComple
> tion;/usr/include/KF5;/usr/include/KF5/KBookmarks;/usr/include/KF5;/usr/incl
> ude/KF5/KItemViews;/usr/include/KF5;/usr/include/KF5/KXmlGui;/usr/include/KF
> 5;/usr/include/KF5/Solid;/usr/include/KF5;/usr/include/KF5/KI18n;/usr/includ
> e/KF5;/usr/include/KF5/KNotifications;/usr/include/KF5;/usr/include/KF5/KIco
> nThemes;/usr/include/KF5;/usr/include/KF5/KWindowSystem;/usr/include;/usr/in
> clude;/usr/include/KF5;/usr/include/KF5;/usr/include/KF5/KGuiAddons;/usr/inc
> lude/KF5;/usr/include/KF5/KUnitConversion;/usr/include/KF5;/usr/include/KF5/
> KTextWidgets;/usr/include/KF5;/usr/include/KF5/SonnetUi;/usr/include/KF5;/us
> r/include/KF5/KParts;/usr/include/KF5" -I/usr/include/x86_64-linux-gnu/qt5
> -I/usr/include/x86_64-linux-gnu/qt5/QtCore
> -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++-64
> -I/usr/include/x86_64-linux-gnu/qt5
> -I/usr/include/x86_64-linux-gnu/qt5/QtGui
> -I/usr/include/x86_64-linux-gnu/qt5/QtCore
> -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++-64
> -I/usr/include/x86_64-linux-gnu/qt5
> -I/usr/include/x86_64-linux-gnu/qt5/QtXml
> -I/usr/include/x86_64-linux-gnu/qt5/QtCore
> -I/usr/lib/x86_64-linux-gnu/qt5/mkspecs/linux-g++-64
> -I/home/boud/kde/src/calligra/libs/koplugin
> -I/home/boud/kde/src/calligra/libs/version
> -I/home/boud/kde/build/calligra/libs/version
> -I/home/boud/kde/src/calligra/libs/pigment
> -I/home/boud/kde/src/calligra/libs/pigment/compositeops
> -I/home/boud/kde/src/calligra/libs/pigment/resources -I/usr/include
> -I/usr/include -I/usr/include/OpenEXR -I/usr/include -mavx -DVC_IMPL=AVX
> -c -oKoOptimizedCompositeOpFactoryPerArch_AVX.cpp.o
> /home/boud/kde/src/calligra/libs/pigment/compositeops/KoOptimizedCompositeOp
> FactoryPerArch.cpp In file included from
> /home/boud/kde/src/calligra/libs/pigment/DebugPigment.h:23:0,
>                       from
> /home/boud/kde/src/calligra/libs/pigment/compositeops/KoOptimizedCompositeOp
> FactoryPerArch.cpp:23:
> /home/boud/kde/src/calligra/libs/pigment/pigment_export.h:24:23: fatal
> error: kdemacros.h: No such file or directory
>       #include <kdemacros.h>
>                             ^
>      compilation terminated.
>      libs/pigment/CMakeFiles/pigmentcms.dir/build.make:72: recipe for
> target 'libs/pigment/KoOptimizedCompositeOpFactoryPerArch_AVX.cpp.o'
> failed
> 
> 
> And that's where I'm totally stuck. It seems the cmake 3.0/kf5/e-c-m (I
> don't know where this system came from) is incompatible with a key libary
> that I have to use. We can't drop using Vc, we cannot move to a newer
> release of Vc and I can't see a way to replicate the functionality of
> vc_compile_for_all_implementations in our own cmake code either, so please
> help!

The issue here is that Vc's macros implicitly assume that all compilation 
flags (including include paths) are done at the directory level (with 
include_directories() and setting CMAKE_CXX_FLAGS etc), while CMake is moving 
towards doing things at the target level (with target_include_directories(), 
target_compile_options() and inheritance from targets passed to 
target_link_libraries()).

Now, from the interface of the  vc_compile_for_all_implementations macro, I'm 
guessing that it is run before you've even created the relevant target, let 
alone called target_link_libraries() on it. That makes things a bit tricky.

Basically, as far as I can see, you have two options. One is to use the old 
CMake style of calling include_directories() all over the place in your CMake 
code (eg: include_directories(${Qt5Core_INCLUDE_DIRS}) when you are going to 
be linking against Qt5::Core). I'm not sure if we expose the relevant variable 
properly in KF5 for that approach, though.

The other is to create a variant of vc_compile_for_all_implementations that 
takes a target rather than a variable to receive object files - this should 
ideally use generator expressions to extract include directories etc, but I'm 
not sure if generator expressions are powerful enough to deal with the compile 
flags properly.

Alex