On 2016-01-21 21:23-0500 Hazen Babcock wrote:
>
> Hello,
>
> As Qt4 is now at least technically no longer supported I thought I might
> spend some time to see if I could get our PyQt bindings to work with Qt5.
> However unfortunately I can't even build PLplot with Qt5 due to a cmake
> error. Any suggestions would be appreciated.
>
> The error message:
>
> CMake Error at bindings/qt_gui/CMakeLists.txt:54 (target_link_libraries):
> The plain signature for target_link_libraries has already been used with
> the target "plplotqt". All uses of target_link_libraries with a target
> must be either all-keyword or all-plain.
>
> The uses of the plain signature are here:
>
> * /usr/lib/x86_64-linux-gnu/cmake/Qt5Core/Qt5CoreMacros.cmake:278
> (target_link_libraries)
>
>
> I used this command in my build directory:
> cmake -DPLPLOT_USE_QT5=ON ../plplot > cmake.txt 2>&1
Hi Hazen:
If you compare the two target_link_libraries commands on the exact
lines mentioned in the error message, bindings/qt_gui/CMakeLists.txt
uses the PRIVATE keyword, and Qt5CoreMacros.cmake uses no keywords at
all, and apparently from the error message that combination of keyword
signature and plain text signature for target_link_libraries commands
for the same target is not allowed by CMake.
I had success with a build of PLplot against Qt5 some time ago. But I am pretty
sure that predated May 2015 when "git blame" tells me I introduced
that PRIVATE keyword in bindings/qt_gui/CMakeLists.txt. So I would
try locally removing PRIVATE from the offending line in
bindings/qt_gui/CMakeLists.txt. That might introduce some
overlinking issues, but I don't think you have to be concerned with
those.
Also, please follow the advice in the first two lines of cmake.txt,
namely
-- WARNING: CMAKE_VERSION = 3.2.2 is in the range from 3.2 through 3.3.1 which
has
a compromised find ability that was fixed in 3.3.2. Please upgrade to
3.3.2 or greater.
I suggest trying 3.3.2 instead of exploring 3.4.x territory just yet
because we have a lot of good experience with 3.3.2, and we have little
experience of any kind with 3.4.x.
Anyhow, with the above workaround and CMake-3.3.2, I think you
should likely be able to build PLplot against Qt5, but let me
know if you encounter any further issues.
By the way, Qt4 is virtually CMake-unaware so that CMake has to do
everything for it in house (but in a well-understood and stable way
that virtually always works). In contrast Qt5 supplies a lot of CMake
support files that help CMake figure out how to build software against
Qt5, but there is a lot of churn on both the CMake side and Qt5 side
on how the two work together. Part of that churn is there are about 4
different build methods of various vintages that are supported for the
two working together. I chose the most modern of those methods that
was available for our minimum CMake version at the time, but our CMake
minimum version is higher now so I might be able to use a still more
modern build method which might avoid the above issue altogether.
Although I don't have time to explore that possibility any time soon,
it is something to keep in mind for the future.
Alan
__________________________
Alan W. Irwin
Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).
Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
__________________________
Linux-powered Science
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