MantisBT - CMake
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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).
Steps To Reproduce
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Issue History
Date ModifiedUsernameFieldChange
2013-01-10 07:01jguNew Issue
2013-01-10 08:11Rolf Eike BeerNote Added: 0032088
2013-01-10 08:27jguNote Added: 0032089
2013-01-10 08:37Rolf Eike BeerNote Added: 0032090
2013-01-10 08:42jguNote Added: 0032091
2016-06-10 14:28Kitware RobotNote Added: 0042197
2016-06-10 14:28Kitware RobotStatusnew => resolved
2016-06-10 14:28Kitware RobotResolutionopen => moved
2016-06-10 14:28Kitware RobotAssigned To => Kitware Robot
2016-06-10 14:31Kitware RobotStatusresolved => closed

Notes
(0032088)
Rolf Eike Beer   
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   
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   
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   
2013-01-10 08:42   
Nope, it doesn't show up at all in link.txt I'm afraid.
(0042197)
Kitware Robot   
2016-06-10 14:28   
Resolving issue as `moved`.

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