maintainer-feedback requested: [Bug 270954] devel/cmake-core: lots of armv7 build failures with "No SOURCES given to target"

[bugzilla-noreply at freebsd.org]

Bugzilla Automation <bugzilla at FreeBSD.org> has asked freebsd-kde (Team)
<kde at FreeBSD.org> for maintainer-feedback:
Bug 270954: devel/cmake-core: lots of armv7 build failures with "No SOURCES
given to target"
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=270954



--- Description ---
Many ports fail on armv7 with the same class of error message:

-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at
/wrkdirs/usr/ports/graphics/pfstools/work/.build/CMakeFiles/CMakeTmp/CMakeLists
.txt:14
(add_executable):
  No SOURCES given to target: cmTC_7730d


CMake Error at /usr/local/share/cmake/Modules/FindOpenMP.cmake:261
(try_compile):
  Failed to generate test project build system.
Call Stack (most recent call first):
  /usr/local/share/cmake/Modules/FindOpenMP.cmake:537 (_OPENMP_GET_FLAGS)
  CMakeLists.txt:39 (find_package)


-- Configuring incomplete, errors occurred!
See also
"/wrkdirs/usr/ports/graphics/pfstools/work/.build/CMakeFiles/CMakeOutput.log".
*** Error code 1

This affects at least the following ports (tested on 2023Q2):

graphics/oyranos
audio/fluidsynth
cad/gmsh
science/gromacs
math/cimod
lang/halide 
games/regoth
misc/openmvg
cad/FreeCAD
graphics/cloudcompare
math/blaze
science/gnudatalanguage
graphics/pfstool

Without having investigated this at all, the cause may be connected with LLVM
not supporting OpenMP on armv6/armv7.  The offending file FindOpenMP.cmake is
installed by devel/cmake-core.	Unfortunately I am not very familiar with cmake
and don't really have any idea on what the cause could be.