[CMake] MSYS2 broken CMAKE_PREFIX_PATH

[Alan W. Irwin]

On 2018-02-11 15:13+0100 Mario Emmenlauer wrote:

>
> I use mingw-w64-x86_64-cmake 3.10.2 on MSYS2. Generally it works well,
> but just recently I started to have problems with CMAKE_PREFIX_PATH.
> Its possible that the problems have been there forever, but I now just
> found them due to a better use of CI systems.
>
> The problem is that cmake is not finding package configuration files
> correctly. I have such files in DESTDIR/lib/cmake, i.e. for a library
> XXX there are typically files XXXConfig.cmake, XXXConfigVersion.cmake
> and XXXTargets.cmake (i.e. for Qt, VTK and others).
>
> But they are not found when I specify CMAKE_PREFIX_PATH=DESTDIR/lib/cmake
> in Unix path style. It does work when I specify the package configuration
> directory in Windows style! This makes things quite confusing, because many
> find_xxx() commands for headers and libraries work with Unix paths. So now
> I need to use CMAKE_PREFIX_PATH=UNIXDESTDIR for the normal find_xxx(), but
> add WINDESTDIR\lib\cmake for the package configuration files (*).
>
> Is this an MSYS2 issue or a standard cmake issue? I reported it with MSYS2
> here https://github.com/Alexpux/MINGW-packages/issues/3337 in case someone
> can comment?

Hi Mario:

>From <https://github.com/msys2/msys2/wiki/MSYS2-introduction>, and
what you said above it appears you are using the "native Windows"
cmake version from the mingw64 repository rather than the POSIX-style
cmake package you can install from the msys2 repository.  I am pretty
sure the native version would not do well with non-native POSIX-style
paths so I am not surprised by your results.  Anyhow, I suggest you
experiment with native versus POSIX cmake packages in both CMD and
bash (from msys2) environments to establish what the different results
are in those four cases for native Windows and POSIX paths.

Note I have no access to MinGW-w64/MSYS2 myself, but I do pay close
attention to this platform because it is the best Windows platform for
PLplot according to a fellow PLplot developer who does have a lot of
practical experience with this platform.

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).
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Linux-powered Science
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