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IDProjectCategoryView StatusDate SubmittedLast Update
0013843CMakeModulespublic2013-01-10 07:012016-06-10 14:31
Reporterjgu 
Assigned ToKitware Robot 
PrioritynormalSeverityminorReproducibilityalways
StatusclosedResolutionmoved 
PlatformLinuxOSFedoraOS Version17
Product VersionCMake 2.8.9 
Target VersionFixed in Version 
Summary0013843: FindMPI doesn't set MPI_C_LINK_FLAGS or MPI_C_COMPILE_FLAGS (and same for CXX)
DescriptionI have a project which does a find_package(MPI). I use the following snippet to print out all variables:

get_cmake_property(_variableNames VARIABLES)
foreach (_variableName ${_variableNames})
   message(STATUS "${_variableName}=${${_variableName}}")
endforeach()

which produces for the MPI relevant variables:

-- MPIEXEC=/usr/lib64/openmpi/bin/mpiexec
-- MPIEXEC_MAX_NUMPROCS=2
-- MPIEXEC_NUMPROC_FLAG=-np
-- MPIEXEC_POSTFLAGS=
-- MPIEXEC_PREFLAGS=
-- MPI_COMPILER=/usr/lib64/openmpi/bin/mpicxx
-- MPI_COMPILER_IS_EXECUTABLE=0
-- MPI_CXX_COMPILER=/usr/lib64/openmpi/bin/mpicxx
-- MPI_CXX_COMPILE_FLAGS=
-- MPI_CXX_FOUND=TRUE
-- MPI_CXX_INCLUDE_PATH=/usr/include/openmpi-x86_64
-- MPI_CXX_LIBRARIES=/usr/lib64/openmpi/lib/libmpi_cxx.so;/usr/lib64/openmpi/lib/libmpi.so;/usr/lib64/libdl.so
-- MPI_CXX_LINK_FLAGS=
-- MPI_C_COMPILER=/usr/lib64/openmpi/bin/mpicc
-- MPI_C_COMPILE_FLAGS=
-- MPI_C_FOUND=TRUE
-- MPI_C_INCLUDE_PATH=/usr/include/openmpi-x86_64
-- MPI_C_LIBRARIES=/usr/lib64/openmpi/lib/libmpi.so;/usr/lib64/libdl.so
-- MPI_C_LINK_FLAGS=
-- MPI_EXTRA_LIBRARY=/usr/lib64/openmpi/lib/libmpi.so;/usr/lib64/libdl.so
-- MPI_EXTRA_LIBRARY_WORK=/usr/lib64/openmpi/lib/libmpi.so;/usr/lib64/libdl.so
-- MPI_FOUND=TRUE
-- MPI_HEADER_PATH=MPI_HEADER_PATH-NOTFOUND
-- MPI_INCLUDE_PATH=/usr/include/openmpi-x86_64
-- MPI_LIB=MPI_LIB-NOTFOUND
-- MPI_LIBRARIES=/usr/lib64/openmpi/lib/libmpi_cxx.so;/usr/lib64/openmpi/lib/libmpi.so;/usr/lib64/libdl.so
-- MPI_LIBRARY=/usr/lib64/openmpi/lib/libmpi_cxx.so
-- MPI_LIBRARY_WORK=/usr/lib64/openmpi/lib/libmpi_cxx.so
-- MPI_NUMLIBS=3
-- MpiPackageDir=

which shows empty MPI_C_LINK_FLAGS and MPI_C_COMPILE_FLAGS and the same for the equivalent CXX variables. As a result, even though my project has this:

set_target_properties(myexec PROPERTIES
  COMPILE_FLAGS "${MPI_C_COMPILE_FLAGS}"
  COMPILE_DEFINITIONS "BUILD_WITH_MPI"
  LINK_FLAGS "${MPI_C_LINK_FLAGS}"
)

it fails to link against mpi (-lmpi is missing, for a start).
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  Notes
(0032088)
Rolf Eike Beer (developer)
2013-01-10 08:11

 -lmpi will never show up in link flags. You have MPI_CXX_LIBRARIES and MPI_C_LIBRARIES which you feed into target_link_libraries.

I have no idea about the compile flags.
(0032089)
jgu (reporter)
2013-01-10 08:27

 Yes, I do that already i.e. I have

target_link_libraries (myexec "${MPI_C_LIBRARIES"}) in my CMakeLists.txt

But, what this does is add the mpi library path as a -L argument, but it doesn't add the needed -lmpi - in the output I posted above, you'll see

MPI_C_LIBRARIES=/usr/lib64/openmpi/lib/libmpi.so;/usr/lib64/libdl.so

-lmpi is a link time compiler flag, so I am surprised it's not appearing in MPI_C_LINK_FLAGS
(0032090)
Rolf Eike Beer (developer)
2013-01-10 08:37

 I'm sure you can still find it in your link.txt in the build tree for myexec.
(0032091)
jgu (reporter)
2013-01-10 08:42

 Nope, it doesn't show up at all in link.txt I'm afraid.
(0042197)
Kitware Robot (administrator)
2016-06-10 14:28

 Resolving issue as `moved`.

This issue tracker is no longer used. Further discussion of this issue may take place in the current CMake Issues page linked in the banner at the top of this page.

 Issue History
Date Modified Username Field Change
2013-01-10 07:01 jgu New Issue
2013-01-10 08:11 Rolf Eike Beer Note Added: 0032088
2013-01-10 08:27 jgu Note Added: 0032089
2013-01-10 08:37 Rolf Eike Beer Note Added: 0032090
2013-01-10 08:42 jgu Note Added: 0032091
2016-06-10 14:28 Kitware Robot Note Added: 0042197
2016-06-10 14:28 Kitware Robot Status new => resolved
2016-06-10 14:28 Kitware Robot Resolution open => moved
2016-06-10 14:28 Kitware Robot Assigned To => Kitware Robot
2016-06-10 14:31 Kitware Robot Status resolved => closed

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