FindMPI.cmake 82.5 KB
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# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.

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#.rst:
# FindMPI
# -------
#
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# Find a Message Passing Interface (MPI) implementation.
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#
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# The Message Passing Interface (MPI) is a library used to write
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# high-performance distributed-memory parallel applications, and is
# typically deployed on a cluster.  MPI is a standard interface (defined
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# by the MPI forum) for which many implementations are available.
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#
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# Variables for using MPI
# ^^^^^^^^^^^^^^^^^^^^^^^
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#
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# The module exposes the components ``C``, ``CXX``, ``MPICXX`` and ``Fortran``.
# Each of these controls the various MPI languages to search for.
# The difference between ``CXX`` and ``MPICXX`` is that ``CXX`` refers to the
# MPI C API being usable from C++, whereas ``MPICXX`` refers to the MPI-2 C++ API
# that was removed again in MPI-3.
#
# Depending on the enabled components the following variables will be set:
#
# ``MPI_FOUND``
#   Variable indicating that MPI settings for all requested languages have been found.
#   If no components are specified, this is true if MPI settings for all enabled languages
#   were detected. Note that the ``MPICXX`` component does not affect this variable.
# ``MPI_VERSION``
#   Minimal version of MPI detected among the requested languages, or all enabled languages
#   if no components were specified.
#
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# This module will set the following variables per language in your
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# project, where ``<lang>`` is one of C, CXX, or Fortran:
#
# ``MPI_<lang>_FOUND``
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#   Variable indicating the MPI settings for ``<lang>`` were found and that
#   simple MPI test programs compile with the provided settings.
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# ``MPI_<lang>_COMPILER``
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#   MPI compiler for ``<lang>`` if such a program exists.
# ``MPI_<lang>_COMPILE_OPTIONS``
#   Compilation options for MPI programs in ``<lang>``, given as a :ref:`;-list <CMake Language Lists>`.
# ``MPI_<lang>_COMPILE_DEFINITIONS``
#   Compilation definitions for MPI programs in ``<lang>``, given as a :ref:`;-list <CMake Language Lists>`.
# ``MPI_<lang>_INCLUDE_DIRS``
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#   Include path(s) for MPI header.
# ``MPI_<lang>_LINK_FLAGS``
#   Linker flags for MPI programs.
# ``MPI_<lang>_LIBRARIES``
#   All libraries to link MPI programs against.
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#
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# Additionally, the following :prop_tgt:`IMPORTED` targets are defined:
#
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# ``MPI::MPI_<lang>``
#   Target for using MPI from ``<lang>``.
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#
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# The following variables indicating which bindings are present will be defined:
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#
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# ``MPI_MPICXX_FOUND``
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#   Variable indicating whether the MPI-2 C++ bindings are present (introduced in MPI-2, removed with MPI-3).
# ``MPI_Fortran_HAVE_F77_HEADER``
#   True if the Fortran 77 header ``mpif.h`` is available.
# ``MPI_Fortran_HAVE_F90_MODULE``
#   True if the Fortran 90 module ``mpi`` can be used for accessing MPI (MPI-2 and higher only).
# ``MPI_Fortran_HAVE_F08_MODULE``
#   True if the Fortran 2008 ``mpi_f08`` is available to MPI programs (MPI-3 and higher only).
#
# If possible, the MPI version will be determined by this module. The facilities to detect the MPI version
# were introduced with MPI-1.2, and therefore cannot be found for older MPI versions.
#
# ``MPI_<lang>_VERSION_MAJOR``
#   Major version of MPI implemented for ``<lang>`` by the MPI distribution.
# ``MPI_<lang>_VERSION_MINOR``
#   Minor version of MPI implemented for ``<lang>`` by the MPI distribution.
# ``MPI_<lang>_VERSION``
#   MPI version implemented for ``<lang>`` by the MPI distribution.
#
# Note that there's no variable for the C bindings being accessible through ``mpi.h``, since the MPI standards
# always have required this binding to work in both C and C++ code.
#
# For running MPI programs, the module sets the following variables
#
# ``MPIEXEC_EXECUTABLE``
#   Executable for running MPI programs, if such exists.
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# ``MPIEXEC_NUMPROC_FLAG``
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#   Flag to pass to ``mpiexec`` before giving it the number of processors to run on.
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# ``MPIEXEC_MAX_NUMPROCS``
#   Number of MPI processors to utilize. Defaults to the number
#   of processors detected on the host system.
# ``MPIEXEC_PREFLAGS``
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#   Flags to pass to ``mpiexec`` directly before the executable to run.
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# ``MPIEXEC_POSTFLAGS``
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#   Flags to pass to ``mpiexec`` after other flags.
#
# Variables for locating MPI
# ^^^^^^^^^^^^^^^^^^^^^^^^^^
#
# This module performs a three step search for an MPI implementation:
#
# 1. Check if the compiler has MPI support built-in. This is the case if the user passed a
#    compiler wrapper as ``CMAKE_<LANG>_COMPILER`` or if they're on a Cray system.
# 2. Attempt to find an MPI compiler wrapper and determine the compiler information from it.
# 3. Try to find an MPI implementation that does not ship such a wrapper by guessing settings.
#    Currently, only Microsoft MPI and MPICH2 on Windows are supported.
#
# For controlling the second step, the following variables may be set:
#
# ``MPI_<lang>_COMPILER``
#   Search for the specified compiler wrapper and use it.
# ``MPI_<lang>_COMPILER_FLAGS``
#   Flags to pass to the MPI compiler wrapper during interrogation. Some compiler wrappers
#   support linking debug or tracing libraries if a specific flag is passed and this variable
#   may be used to obtain them.
# ``MPI_COMPILER_FLAGS``
#   Used to initialize ``MPI_<lang>_COMPILER_FLAGS`` if no language specific flag has been given.
#   Empty by default.
# ``MPI_EXECUTABLE_SUFFIX``
#   A suffix which is appended to all names that are being looked for. For instance you may set this
#   to ``.mpich`` or ``.openmpi`` to prefer the one or the other on Debian and its derivatives.
#
# In order to control the guessing step, the following variable may be set:
#
# ``MPI_GUESS_LIBRARY_NAME``
#   Valid values are ``MSMPI`` and ``MPICH2``. If set, only the given library will be searched for.
#   By default, ``MSMPI`` will be preferred over ``MPICH2`` if both are available.
#   This also sets ``MPI_SKIP_COMPILER_WRAPPER`` to ``true``, which may be overridden.
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#
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# Each of the search steps may be skipped with the following control variables:
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#
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# ``MPI_ASSUME_NO_BUILTIN_MPI``
#   If true, the module assumes that the compiler itself does not provide an MPI implementation and
#   skips to step 2.
# ``MPI_SKIP_COMPILER_WRAPPER``
#   If true, no compiler wrapper will be searched for.
# ``MPI_SKIP_GUESSING``
#   If true, the guessing step will be skipped.
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#
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# Additionally, the following control variable is available to change search behavior:
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#
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# ``MPI_CXX_SKIP_MPICXX``
#   Add some definitions that will disable the MPI-2 C++ bindings.
#   Currently supported are MPICH, Open MPI, Platform MPI and derivatives thereof,
#   for example MVAPICH or Intel MPI.
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#
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# If the find procedure fails for a variable ``MPI_<lang>_WORKS``, then the settings detected by or passed to
# the module did not work and even a simple MPI test program failed to compile.
#
# If all of these parameters were not sufficient to find the right MPI implementation, a user may
# disable the entire autodetection process by specifying both a list of libraries in ``MPI_<lang>_LIBRARIES``
# and a list of include directories in ``MPI_<lang>_ADDITIONAL_INCLUDE_DIRS``.
# Any other variable may be set in addition to these two. The module will then validate the MPI settings and store the
# settings in the cache.
#
# Cache variables for MPI
# ^^^^^^^^^^^^^^^^^^^^^^^
#
# The variable ``MPI_<lang>_INCLUDE_DIRS`` will be assembled from the following variables.
# For C and CXX:
#
# ``MPI_<lang>_HEADER_DIR``
#   Location of the ``mpi.h`` header on disk.
#
# For Fortran:
#
# ``MPI_Fortran_F77_HEADER_DIR``
#   Location of the Fortran 77 header ``mpif.h``, if it exists.
# ``MPI_Fortran_MODULE_DIR``
#   Location of the ``mpi`` or ``mpi_f08`` modules, if available.
#
# For all languages the following variables are additionally considered:
#
# ``MPI_<lang>_ADDITIONAL_INCLUDE_DIRS``
#   A :ref:`;-list <CMake Language Lists>` of paths needed in addition to the normal include directories.
# ``MPI_<include_name>_INCLUDE_DIR``
#   Path variables for include folders referred to by ``<include_name>``.
# ``MPI_<lang>_ADDITIONAL_INCLUDE_VARS``
#   A :ref:`;-list <CMake Language Lists>` of ``<include_name>`` that will be added to the include locations of ``<lang>``.
#
# The variable ``MPI_<lang>_LIBRARIES`` will be assembled from the following variables:
#
# ``MPI_<lib_name>_LIBRARY``
#   The location of a library called ``<lib_name>`` for use with MPI.
# ``MPI_<lang>_LIB_NAMES``
#   A :ref:`;-list <CMake Language Lists>` of ``<lib_name>`` that will be added to the include locations of ``<lang>``.
#
# Usage of mpiexec
# ^^^^^^^^^^^^^^^^
#
# When using ``MPIEXEC_EXECUTABLE`` to execute MPI applications, you should typically
# use all of the ``MPIEXEC_EXECUTABLE`` flags as follows:
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#
# ::
#
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#    ${MPIEXEC_EXECUTABLE} ${MPIEXEC_NUMPROC_FLAG} ${MPIEXEC_MAX_NUMPROCS}
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#      ${MPIEXEC_PREFLAGS} EXECUTABLE ${MPIEXEC_POSTFLAGS} ARGS
#
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# where ``EXECUTABLE`` is the MPI program, and ``ARGS`` are the arguments to
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# pass to the MPI program.
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#
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# Advanced variables for using MPI
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
#
# The module can perform some advanced feature detections upon explicit request.
#
# **Important notice:** The following checks cannot be performed without *executing* an MPI test program.
# Consider the special considerations for the behavior of :command:`try_run` during cross compilation.
# Moreover, running an MPI program can cause additional issues, like a firewall notification on some systems.
# You should only enable these detections if you absolutely need the information.
#
# If the following variables are set to true, the respective search will be performed:
#
# ``MPI_DETERMINE_Fortran_CAPABILITIES``
#   Determine for all available Fortran bindings what the values of ``MPI_SUBARRAYS_SUPPORTED`` and
#   ``MPI_ASYNC_PROTECTS_NONBLOCKING`` are and make their values available as ``MPI_Fortran_<binding>_SUBARRAYS``
#   and ``MPI_Fortran_<binding>_ASYNCPROT``, where ``<binding>`` is one of ``F77_HEADER``, ``F90_MODULE`` and
#   ``F08_MODULE``.
# ``MPI_DETERMINE_LIBRARY_VERSION``
#   For each language, find the output of ``MPI_Get_library_version`` and make it available as ``MPI_<lang>_LIBRARY_VERSION``.
#   This information is usually tied to the runtime component of an MPI implementation and might differ depending on ``<lang>``.
#   Note that the return value is entirely implementation defined. This information might be used to identify
#   the MPI vendor and for example pick the correct one of multiple third party binaries that matches the MPI vendor.
#
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# Backward Compatibility
# ^^^^^^^^^^^^^^^^^^^^^^
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#
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# For backward compatibility with older versions of FindMPI, these
# variables are set, but deprecated:
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#
# ::
#
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#    MPI_COMPILER        MPI_LIBRARY        MPI_EXTRA_LIBRARY
#    MPI_COMPILE_FLAGS   MPI_INCLUDE_PATH   MPI_LINK_FLAGS
#    MPI_LIBRARIES
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#
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# In new projects, please use the ``MPI_<lang>_XXX`` equivalents.
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# Additionally, the following variables are deprecated:
#
# ``MPI_<lang>_COMPILE_FLAGS``
#   Use ``MPI_<lang>_COMPILE_OPTIONS`` and ``MPI_<lang>_COMPILE_DEFINITIONS`` instead.
# ``MPI_<lang>_INCLUDE_PATH``
#   For consumption use ``MPI_<lang>_INCLUDE_DIRS`` and for specifying folders use ``MPI_<lang>_ADDITIONAL_INCLUDE_DIRS`` instead.
# ``MPIEXEC``
#   Use ``MPIEXEC_EXECUTABLE`` instead.
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cmake_policy(PUSH)
cmake_policy(SET CMP0057 NEW) # if IN_LIST
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include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
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# Generic compiler names
set(_MPI_C_GENERIC_COMPILER_NAMES          mpicc    mpcc      mpicc_r mpcc_r)
set(_MPI_CXX_GENERIC_COMPILER_NAMES        mpicxx   mpiCC     mpcxx   mpCC    mpic++   mpc++
                                           mpicxx_r mpiCC_r   mpcxx_r mpCC_r  mpic++_r mpc++_r)
set(_MPI_Fortran_GENERIC_COMPILER_NAMES    mpif95   mpif95_r  mpf95   mpf95_r
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                                           mpif90   mpif90_r  mpf90   mpf90_r
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                                           mpif77   mpif77_r  mpf77   mpf77_r
                                           mpifc)
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# GNU compiler names
set(_MPI_GNU_C_COMPILER_NAMES              mpigcc mpgcc mpigcc_r mpgcc_r)
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set(_MPI_GNU_CXX_COMPILER_NAMES            mpig++ mpg++ mpig++_r mpg++_r mpigxx)
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set(_MPI_GNU_Fortran_COMPILER_NAMES        mpigfortran mpgfortran mpigfortran_r mpgfortran_r
                                           mpig77 mpig77_r mpg77 mpg77_r)

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# Intel MPI compiler names on Windows
if(WIN32)
  list(APPEND _MPI_C_GENERIC_COMPILER_NAMES       mpicc.bat)
  list(APPEND _MPI_CXX_GENERIC_COMPILER_NAMES     mpicxx.bat)
  list(APPEND _MPI_Fortran_GENERIC_COMPILER_NAMES mpifc.bat)

  # Intel MPI compiler names
  set(_MPI_Intel_C_COMPILER_NAMES            mpiicc.bat)
  set(_MPI_Intel_CXX_COMPILER_NAMES          mpiicpc.bat)
  set(_MPI_Intel_Fortran_COMPILER_NAMES      mpiifort.bat mpif77.bat mpif90.bat)

  # Intel MPI compiler names for MSMPI
  set(_MPI_MSVC_C_COMPILER_NAMES             mpicl.bat)
  set(_MPI_MSVC_CXX_COMPILER_NAMES           mpicl.bat)
else()
  # Intel compiler names
  set(_MPI_Intel_C_COMPILER_NAMES            mpiicc)
  set(_MPI_Intel_CXX_COMPILER_NAMES          mpiicpc  mpiicxx mpiic++)
  set(_MPI_Intel_Fortran_COMPILER_NAMES      mpiifort mpiif95 mpiif90 mpiif77)
endif()
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# PGI compiler names
set(_MPI_PGI_C_COMPILER_NAMES              mpipgcc mppgcc)
set(_MPI_PGI_CXX_COMPILER_NAMES            mpipgCC mppgCC)
set(_MPI_PGI_Fortran_COMPILER_NAMES        mpipgf95 mpipgf90 mppgf95 mppgf90 mpipgf77 mppgf77)

# XLC MPI Compiler names
set(_MPI_XL_C_COMPILER_NAMES               mpxlc      mpxlc_r    mpixlc     mpixlc_r)
set(_MPI_XL_CXX_COMPILER_NAMES             mpixlcxx   mpixlC     mpixlc++   mpxlcxx   mpxlc++   mpixlc++   mpxlCC
                                           mpixlcxx_r mpixlC_r   mpixlc++_r mpxlcxx_r mpxlc++_r mpixlc++_r mpxlCC_r)
set(_MPI_XL_Fortran_COMPILER_NAMES         mpixlf95   mpixlf95_r mpxlf95 mpxlf95_r
                                           mpixlf90   mpixlf90_r mpxlf90 mpxlf90_r
                                           mpixlf77   mpixlf77_r mpxlf77 mpxlf77_r
                                           mpixlf     mpixlf_r   mpxlf   mpxlf_r)

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# Prepend vendor-specific compiler wrappers to the list. If we don't know the compiler,
# attempt all of them.
# By attempting vendor-specific compiler names first, we should avoid situations where the compiler wrapper
# stems from a proprietary MPI and won't know which compiler it's being used for. For instance, Intel MPI
# controls its settings via the I_MPI_CC environment variables if the generic name is being used.
# If we know which compiler we're working with, we can use the most specialized wrapper there is in order to
# pick up the right settings for it.
foreach (LANG IN ITEMS C CXX Fortran)
  set(_MPI_${LANG}_COMPILER_NAMES "")
  foreach (id IN ITEMS GNU Intel MSVC PGI XL)
    if (NOT CMAKE_${LANG}_COMPILER_ID OR CMAKE_${LANG}_COMPILER_ID STREQUAL id)
      list(APPEND _MPI_${LANG}_COMPILER_NAMES ${_MPI_${id}_${LANG}_COMPILER_NAMES}${MPI_EXECUTABLE_SUFFIX})
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    endif()
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    unset(_MPI_${id}_${LANG}_COMPILER_NAMES)
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  endforeach()
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  list(APPEND _MPI_${LANG}_COMPILER_NAMES ${_MPI_${LANG}_GENERIC_COMPILER_NAMES}${MPI_EXECUTABLE_SUFFIX})
  unset(_MPI_${LANG}_GENERIC_COMPILER_NAMES)
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endforeach()

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# Names to try for mpiexec
# Only mpiexec commands are guaranteed to behave as described in the standard,
# mpirun commands are not covered by the standard in any way whatsoever.
# lamexec is the executable for LAM/MPI, srun is for SLURM or Open MPI with SLURM support.
# srun -n X <executable> is however a valid command, so it behaves 'like' mpiexec.
set(_MPIEXEC_NAMES_BASE                   mpiexec mpiexec.hydra mpiexec.mpd mpirun lamexec srun)
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unset(_MPIEXEC_NAMES)
foreach(_MPIEXEC_NAME IN LISTS _MPIEXEC_NAMES_BASE)
  list(APPEND _MPIEXEC_NAMES "${_MPIEXEC_NAME}${MPI_EXECUTABLE_SUFFIX}")
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endforeach()
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unset(_MPIEXEC_NAMES_BASE)
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function (_MPI_check_compiler LANG QUERY_FLAG OUTPUT_VARIABLE RESULT_VARIABLE)
  if(DEFINED MPI_${LANG}_COMPILER_FLAGS)
    separate_arguments(_MPI_COMPILER_WRAPPER_OPTIONS NATIVE_COMMAND "${MPI_${LANG}_COMPILER_FLAGS}")
  else()
    separate_arguments(_MPI_COMPILER_WRAPPER_OPTIONS NATIVE_COMMAND "${MPI_COMPILER_FLAGS}")
  endif()
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  execute_process(
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    COMMAND ${MPI_${LANG}_COMPILER} ${_MPI_COMPILER_WRAPPER_OPTIONS} ${QUERY_FLAG}
    OUTPUT_VARIABLE  WRAPPER_OUTPUT OUTPUT_STRIP_TRAILING_WHITESPACE
    ERROR_VARIABLE   WRAPPER_OUTPUT ERROR_STRIP_TRAILING_WHITESPACE
    RESULT_VARIABLE  WRAPPER_RETURN)
  # Some compiler wrappers will yield spurious zero return values, for example
  # Intel MPI tolerates unknown arguments and if the MPI wrappers loads a shared
  # library that has invalid or missing version information there would be warning
  # messages emitted by ld.so in the compiler output. In either case, we'll treat
  # the output as invalid.
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  if("${WRAPPER_OUTPUT}" MATCHES "undefined reference|unrecognized|need to set|no version information available|command not found")
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    set(WRAPPER_RETURN 255)
  endif()
  # Ensure that no error output might be passed upwards.
  if(NOT WRAPPER_RETURN EQUAL 0)
    unset(WRAPPER_OUTPUT)
  endif()
  set(${OUTPUT_VARIABLE} "${WRAPPER_OUTPUT}" PARENT_SCOPE)
  set(${RESULT_VARIABLE} "${WRAPPER_RETURN}" PARENT_SCOPE)
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endfunction()
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macro(_MPI_env_set_ifnot VAR VALUE)
  if(NOT DEFINED ENV{${VAR}})
    set(_MPI_${VAR}_WAS_SET FALSE)
    set(ENV{${VAR}} ${${VALUE}})
  else()
    set(_MPI_${VAR}_WAS_SET TRUE)
  endif()
endmacro()

macro(_MPI_env_unset_ifnot VAR)
  if(NOT _MPI_${VAR}_WAS_SET)
    unset(ENV{${VAR}})
  endif()
endmacro()

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function (_MPI_interrogate_compiler LANG)
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  unset(MPI_COMPILE_CMDLINE)
  unset(MPI_LINK_CMDLINE)

  unset(MPI_COMPILE_OPTIONS_WORK)
  unset(MPI_COMPILE_DEFINITIONS_WORK)
  unset(MPI_INCLUDE_DIRS_WORK)
  unset(MPI_LINK_FLAGS_WORK)
  unset(MPI_LIB_NAMES_WORK)
  unset(MPI_LIB_FULLPATHS_WORK)

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  # Define the MPICH and Intel MPI compiler variables to the compilers set in CMake.
  # It's possible to have a per-compiler configuration in these MPI implementations and
  # a particular MPICH derivate might check compiler interoperability.
  # Intel MPI in particular does this with I_MPI_CHECK_COMPILER.
  file(TO_NATIVE_PATH "${CMAKE_${LANG}_COMPILER}" _MPI_UNDERLAYING_COMPILER)
  # On Windows, the Intel MPI batch scripts can only work with filnames - Full paths will break them.
  # Due to the lack of other MPICH-based wrappers for Visual C++, we may treat this as default.
  if(MSVC)
    get_filename_component(_MPI_UNDERLAYING_COMPILER "${_MPI_UNDERLAYING_COMPILER}" NAME)
  endif()
  if("${LANG}" STREQUAL "C")
    _MPI_env_set_ifnot(I_MPI_CC _MPI_UNDERLAYING_COMPILER)
    _MPI_env_set_ifnot(MPICH_CC _MPI_UNDERLAYING_COMPILER)
  elseif("${LANG}" STREQUAL "CXX")
    _MPI_env_set_ifnot(I_MPI_CXX _MPI_UNDERLAYING_COMPILER)
    _MPI_env_set_ifnot(MPICH_CXX _MPI_UNDERLAYING_COMPILER)
  elseif("${LANG}" STREQUAL "Fortran")
    _MPI_env_set_ifnot(I_MPI_FC _MPI_UNDERLAYING_COMPILER)
    _MPI_env_set_ifnot(MPICH_FC _MPI_UNDERLAYING_COMPILER)
    _MPI_env_set_ifnot(I_MPI_F77 _MPI_UNDERLAYING_COMPILER)
    _MPI_env_set_ifnot(MPICH_F77 _MPI_UNDERLAYING_COMPILER)
    _MPI_env_set_ifnot(I_MPI_F90 _MPI_UNDERLAYING_COMPILER)
    _MPI_env_set_ifnot(MPICH_F90 _MPI_UNDERLAYING_COMPILER)
  endif()

  # Set these two variables for Intel MPI:
  #   - I_MPI_DEBUG_INFO_STRIP: It adds 'objcopy' lines to the compiler output. We support stripping them
  #     (see below), but if we can avoid them in the first place, we should.
  #   - I_MPI_FORT_BIND: By default Intel MPI makes the C/C++ compiler wrappers link Fortran bindings.
  #     This is so that mixed-language code doesn't require additional libraries when linking with mpicc.
  #     For our purposes, this makes little sense, since correct MPI usage from CMake already circumvenes this.
  set(_MPI_ENV_VALUE "disable")
  _MPI_env_set_ifnot(I_MPI_DEBUG_INFO_STRIP _MPI_ENV_VALUE)
  _MPI_env_set_ifnot(I_MPI_FORT_BIND _MPI_ENV_VALUE)

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  # Check whether the -showme:compile option works. This indicates that we have either Open MPI
  # or a newer version of LAM/MPI, and implies that -showme:link will also work.
  # Open MPI also supports -show, but separates linker and compiler information
  _MPI_check_compiler(${LANG} "-showme:compile" MPI_COMPILE_CMDLINE MPI_COMPILER_RETURN)
  if (MPI_COMPILER_RETURN EQUAL 0)
    _MPI_check_compiler(${LANG} "-showme:link" MPI_LINK_CMDLINE MPI_COMPILER_RETURN)

    if (NOT MPI_COMPILER_RETURN EQUAL 0)
      unset(MPI_COMPILE_CMDLINE)
    endif()
  endif()
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  # MPICH and MVAPICH offer -compile-info and -link-info.
  # For modern versions, both do the same as -show. However, for old versions, they do differ
  # when called for mpicxx and mpif90 and it's necessary to use them over -show in order to find the
  # removed MPI C++ bindings.
  if (NOT MPI_COMPILER_RETURN EQUAL 0)
    _MPI_check_compiler(${LANG} "-compile-info" MPI_COMPILE_CMDLINE MPI_COMPILER_RETURN)

    if (MPI_COMPILER_RETURN EQUAL 0)
      _MPI_check_compiler(${LANG} "-link-info" MPI_LINK_CMDLINE MPI_COMPILER_RETURN)
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      if (NOT MPI_COMPILER_RETURN EQUAL 0)
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        unset(MPI_COMPILE_CMDLINE)
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      endif()
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    endif()
  endif()
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  # MPICH, MVAPICH2 and Intel MPI just use "-show". Open MPI also offers this, but the
  # -showme commands are more specialized.
  if (NOT MPI_COMPILER_RETURN EQUAL 0)
    _MPI_check_compiler(${LANG} "-show" MPI_COMPILE_CMDLINE MPI_COMPILER_RETURN)
  endif()
454

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  # Older versions of LAM/MPI have "-showme". Open MPI also supports this.
  # Unknown to MPICH, MVAPICH and Intel MPI.
  if (NOT MPI_COMPILER_RETURN EQUAL 0)
    _MPI_check_compiler(${LANG} "-showme" MPI_COMPILE_CMDLINE MPI_COMPILER_RETURN)
  endif()
460

461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479
  # Revert changes to the environment made previously
  if("${LANG}" STREQUAL "C")
    _MPI_env_unset_ifnot(I_MPI_CC)
    _MPI_env_unset_ifnot(MPICH_CC)
  elseif("${LANG}" STREQUAL "CXX")
    _MPI_env_unset_ifnot(I_MPI_CXX)
    _MPI_env_unset_ifnot(MPICH_CXX)
  elseif("${LANG}" STREQUAL "Fortran")
    _MPI_env_unset_ifnot(I_MPI_FC)
    _MPI_env_unset_ifnot(MPICH_FC)
    _MPI_env_unset_ifnot(I_MPI_F77)
    _MPI_env_unset_ifnot(MPICH_F77)
    _MPI_env_unset_ifnot(I_MPI_F90)
    _MPI_env_unset_ifnot(MPICH_F90)
  endif()

  _MPI_env_unset_ifnot(I_MPI_DEBUG_INFO_STRIP)
  _MPI_env_unset_ifnot(I_MPI_FORT_BIND)

480 481 482 483 484 485
  if (NOT (MPI_COMPILER_RETURN EQUAL 0) OR NOT (DEFINED MPI_COMPILE_CMDLINE))
    # Cannot interrogate this compiler, so exit.
    set(MPI_${LANG}_WRAPPER_FOUND FALSE PARENT_SCOPE)
    return()
  endif()
  unset(MPI_COMPILER_RETURN)
486

487 488 489 490 491 492
  # We have our command lines, but we might need to copy MPI_COMPILE_CMDLINE
  # into MPI_LINK_CMDLINE, if we didn't find the link line.
  if (NOT DEFINED MPI_LINK_CMDLINE)
    set(MPI_LINK_CMDLINE "${MPI_COMPILE_CMDLINE}")
  endif()

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  # Visual Studio parsers permit each flag prefixed by either / or -.
  # We'll normalize this to the - syntax we use for CMake purposes anyways.
  if(MSVC)
    foreach(_MPI_VARIABLE IN ITEMS COMPILE LINK)
      string(REGEX REPLACE "(^| )/" "\\1-" MPI_${_MPI_VARIABLE}_CMDLINE "${MPI_${_MPI_VARIABLE}_CMDLINE}")
      string(REPLACE "-libpath:" "-LIBPATH:" MPI_${_MPI_VARIABLE}_CMDLINE "${MPI_${_MPI_VARIABLE}_CMDLINE}")
    endforeach()
  endif()

502 503 504 505 506
  # For MSVC and cl-compatible compilers, the keyword /link indicates a point after which
  # everything following is passed to the linker. In this case, we drop all prior information
  # from the link line and treat any unknown extra flags as linker flags.
  set(_MPI_FILTERED_LINK_INFORMATION FALSE)
  if(MSVC)
507 508
    if(MPI_LINK_CMDLINE MATCHES " -(link|LINK) ")
      string(REGEX REPLACE ".+-(link|LINK) +" "" MPI_LINK_CMDLINE "${MPI_LINK_CMDLINE}")
509
      set(_MPI_FILTERED_LINK_INFORMATION TRUE)
510
    endif()
511
    string(REGEX REPLACE " +-(link|LINK) .+" "" MPI_COMPILE_CMDLINE "${MPI_COMPILE_CMDLINE}")
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  endif()

  if(UNIX)
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    # At this point, we obtained some output from a compiler wrapper that works.
    # We'll now try to parse it into variables with meaning to us.
    if("${LANG}" STREQUAL "Fortran")
      # If MPICH (and derivates) didn't recognize the Fortran compiler include flag during configuration,
      # they'll return a set of three commands, consisting out of a symlink command for mpif.h,
      # the actual compiler command and deletion of the created symlink.
      # Especially with M(VA)PICH-1, this appears to happen erroneously, and therefore we should translate
      # this output into an additional include directory and then drop it from the output.
      if("${MPI_COMPILE_CMDLINE}" MATCHES "^ln -s ([^\" ]+|\"[^\"]+\") mpif.h")
        get_filename_component(MPI_INCLUDE_DIRS_WORK "${CMAKE_MATCH_1}" DIRECTORY)
        string(REGEX REPLACE "^ln -s ([^\" ]+|\"[^\"]+\") mpif.h\n" "" MPI_COMPILE_CMDLINE "${MPI_COMPILE_CMDLINE}")
        string(REGEX REPLACE "^ln -s ([^\" ]+|\"[^\"]+\") mpif.h\n" "" MPI_LINK_CMDLINE "${MPI_LINK_CMDLINE}")
        string(REGEX REPLACE "\nrm -f mpif.h$" "" MPI_COMPILE_CMDLINE "${MPI_COMPILE_CMDLINE}")
        string(REGEX REPLACE "\nrm -f mpif.h$" "" MPI_LINK_CMDLINE "${MPI_LINK_CMDLINE}")
      endif()
    endif()

    # If Intel MPI was configured for static linkage with -static_mpi, the wrapper will by default strip
    # debug information from resulting binaries (see I_MPI_DEBUG_INFO_STRIP).
    # Since we cannot process this information into CMake logic, we need to discard the resulting objcopy
    # commands from the output.
536 537 538 539
    string(REGEX REPLACE "(^|\n)objcopy[^\n]+(\n|$)" "" MPI_COMPILE_CMDLINE "${MPI_COMPILE_CMDLINE}")
    string(REGEX REPLACE "(^|\n)objcopy[^\n]+(\n|$)" "" MPI_LINK_CMDLINE "${MPI_LINK_CMDLINE}")
  endif()

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  # For Visual C++, extracting compiler options in a generic fashion isn't easy. However, no MPI implementation
  # on Windows seems to require any specific ones, either.
  if(NOT MSVC)
    # Extract compile options from the compile command line.
    string(REGEX MATCHALL "(^| )-f([^\" ]+|\"[^\"]+\")" MPI_ALL_COMPILE_OPTIONS "${MPI_COMPILE_CMDLINE}")

    foreach(_MPI_COMPILE_OPTION IN LISTS MPI_ALL_COMPILE_OPTIONS)
      string(REGEX REPLACE "^ " "" _MPI_COMPILE_OPTION "${_MPI_COMPILE_OPTION}")

      # Ignore -fstack-protector directives: These occur on MPICH and MVAPICH when the libraries
      # themselves were built with this flag. However, this flag is unrelated to using MPI, and
      # we won't match the accompanying --param-ssp-size and -Wp,-D_FORTIFY_SOURCE flags and therefore
      # produce inconsistent results with the regularly flags.
      # Similarly, aliasing flags do not belong into our flag array.
554
      if(NOT "${_MPI_COMPILE_OPTION}" MATCHES "^-f((no-|)(stack-protector|strict-aliasing)|PI[CE]|pi[ce])")
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        list(APPEND MPI_COMPILE_OPTIONS_WORK "${_MPI_COMPILE_OPTION}")
      endif()
    endforeach()
  endif()

  # For GNU-style compilers, it's possible to prefix includes and definitions with certain flags to pass them
  # only to the preprocessor. For CMake purposes, we need to treat, but ignore such scopings.
  # Note that we do not support spaces between the arguments, i.e. -Wp,-I -Wp,/opt/mympi will not be parsed
  # correctly. This form does not seem to occur in any common MPI implementation, however.
  if(NOT MSVC)
    set(_MPI_PREPROCESSOR_FLAG_REGEX "(-Wp,|-Xpreprocessor )?")
  else()
    set(_MPI_PREPROCESSOR_FLAG_REGEX "")
  endif()
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570 571
  # Same deal as above, for the definitions.
  string(REGEX MATCHALL "(^| )${_MPI_PREPROCESSOR_FLAG_REGEX}-D *([^\" ]+|\"[^\"]+\")" MPI_ALL_COMPILE_DEFINITIONS "${MPI_COMPILE_CMDLINE}")
572 573

  foreach(_MPI_COMPILE_DEFINITION IN LISTS MPI_ALL_COMPILE_DEFINITIONS)
574
    string(REGEX REPLACE "^ ?${_MPI_PREPROCESSOR_FLAG_REGEX}-D *" "" _MPI_COMPILE_DEFINITION "${_MPI_COMPILE_DEFINITION}")
575 576 577 578 579 580 581
    string(REPLACE "\"" "" _MPI_COMPILE_DEFINITION "${_MPI_COMPILE_DEFINITION}")
    if(NOT "${_MPI_COMPILE_DEFINITION}" MATCHES "^_FORTIFY_SOURCE.*")
      list(APPEND MPI_COMPILE_DEFINITIONS_WORK "${_MPI_COMPILE_DEFINITION}")
    endif()
  endforeach()

  # Extract include paths from compile command line
582 583
  string(REGEX MATCHALL "(^| )${_MPI_PREPROCESSOR_FLAG_REGEX}${CMAKE_INCLUDE_FLAG_${LANG}} *([^\" ]+|\"[^\"]+\")"
    MPI_ALL_INCLUDE_PATHS "${MPI_COMPILE_CMDLINE}")
584 585

  # If extracting failed to work, we'll try using -showme:incdirs.
586 587
  # Unlike before, we do this without the environment variables set up, but since only MPICH derivates are affected by any of them, and
  # -showme:... is only supported by Open MPI and LAM/MPI, this isn't a concern.
588 589 590 591 592 593 594 595
  if (NOT MPI_ALL_INCLUDE_PATHS)
    _MPI_check_compiler(${LANG} "-showme:incdirs" MPI_INCDIRS_CMDLINE MPI_INCDIRS_COMPILER_RETURN)
    if(MPI_INCDIRS_COMPILER_RETURN)
      separate_arguments(MPI_ALL_INCLUDE_PATHS NATIVE_COMMAND "${MPI_INCDIRS_CMDLINE}")
    endif()
  endif()

  foreach(_MPI_INCLUDE_PATH IN LISTS MPI_ALL_INCLUDE_PATHS)
596
    string(REGEX REPLACE "^ ?${_MPI_PREPROCESSOR_FLAG_REGEX}${CMAKE_INCLUDE_FLAG_${LANG}} *" "" _MPI_INCLUDE_PATH "${_MPI_INCLUDE_PATH}")
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    string(REPLACE "\"" "" _MPI_INCLUDE_PATH "${_MPI_INCLUDE_PATH}")
    get_filename_component(_MPI_INCLUDE_PATH "${_MPI_INCLUDE_PATH}" REALPATH)
    list(APPEND MPI_INCLUDE_DIRS_WORK "${_MPI_INCLUDE_PATH}")
  endforeach()

602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652
  # The next step are linker flags and library directories. Here, we first take the flags given in raw -L or -LIBPATH: syntax.
  string(REGEX MATCHALL "(^| )${CMAKE_LIBRARY_PATH_FLAG} *([^\" ]+|\"[^\"]+\")" MPI_DIRECT_LINK_PATHS "${MPI_LINK_CMDLINE}")
  foreach(_MPI_LPATH IN LISTS MPI_DIRECT_LINK_PATHS)
    string(REGEX REPLACE "(^| )${CMAKE_LIBRARY_PATH_FLAG} *" "" _MPI_LPATH "${_MPI_LPATH}")
    list(APPEND MPI_ALL_LINK_PATHS "${_MPI_LPATH}")
  endforeach()

  # If the link commandline hasn't been filtered (e.g. when using MSVC and /link), we need to extract the relevant parts first.
  if(NOT _MPI_FILTERED_LINK_INFORMATION)
    string(REGEX MATCHALL "(^| )(-Wl,|-Xlinker +)([^\" ]+|\"[^\"]+\")" MPI_LINK_FLAGS "${MPI_LINK_CMDLINE}")

    # In this case, we could also find some indirectly given linker paths, e.g. prefixed by -Xlinker or -Wl,
    # Since syntaxes like -Wl,-L -Wl,/my/path/to/lib are also valid, we parse these paths by first removing -Wl, and -Xlinker
    # from the list of filtered flags and then parse the remainder of the output.
    string(REGEX REPLACE "(-Wl,|-Xlinker +)" "" MPI_LINK_FLAGS_RAW "${MPI_LINK_FLAGS}")

    # Now we can parse the leftover output. Note that spaces can now be handled since the above example would reduce to
    # -L /my/path/to/lib and can be extracted correctly.
    string(REGEX MATCHALL "^(${CMAKE_LIBRARY_PATH_FLAG},? *|--library-path=)([^\" ]+|\"[^\"]+\")"
      MPI_INDIRECT_LINK_PATHS "${MPI_LINK_FLAGS_RAW}")

    foreach(_MPI_LPATH IN LISTS MPI_INDIRECT_LINK_PATHS)
      string(REGEX REPLACE "^(${CMAKE_LIBRARY_PATH_FLAG},? *|--library-path=)" "" _MPI_LPATH "${_MPI_LPATH}")
      list(APPEND MPI_ALL_LINK_PATHS "${_MPI_LPATH}")
    endforeach()

    # We need to remove the flags we extracted from the linker flag list now.
    string(REGEX REPLACE "(^| )(-Wl,|-Xlinker +)(${CMAKE_LIBRARY_PATH_FLAG},? *(-Wl,|-Xlinker +)?|--library-path=)([^\" ]+|\"[^\"]+\")" ""
      MPI_LINK_CMDLINE_FILTERED "${MPI_LINK_CMDLINE}")

    # Some MPI implementations pass on options they themselves were built with. Since -z,noexecstack is a common
    # hardening, we should strip it. In general, the -z options should be undesirable.
    string(REGEX REPLACE "(^| )-Wl,-z(,[^ ]+| +-Wl,[^ ]+)" "" MPI_LINK_CMDLINE_FILTERED "${MPI_LINK_CMDLINE_FILTERED}")
    string(REGEX REPLACE "(^| )-Xlinker +-z +-Xlinker +[^ ]+" "" MPI_LINK_CMDLINE_FILTERED "${MPI_LINK_CMDLINE_FILTERED}")

    # We only consider options of the form -Wl or -Xlinker:
    string(REGEX MATCHALL "(^| )(-Wl,|-Xlinker +)([^\" ]+|\"[^\"]+\")" MPI_ALL_LINK_FLAGS "${MPI_LINK_CMDLINE_FILTERED}")

    # As a next step, we assemble the linker flags extracted in a preliminary flags string
    foreach(_MPI_LINK_FLAG IN LISTS MPI_ALL_LINK_FLAGS)
      string(STRIP "${_MPI_LINK_FLAG}" _MPI_LINK_FLAG)
      if (MPI_LINK_FLAGS_WORK)
        string(APPEND MPI_LINK_FLAGS_WORK " ${_MPI_LINK_FLAG}")
      else()
        set(MPI_LINK_FLAGS_WORK "${_MPI_LINK_FLAG}")
      endif()
    endforeach()
  else()
    # In the filtered case, we obtain the link time flags by just stripping the library paths.
    string(REGEX REPLACE "(^| )${CMAKE_LIBRARY_PATH_FLAG} *([^\" ]+|\"[^\"]+\")" "" MPI_LINK_CMDLINE_FILTERED "${MPI_LINK_CMDLINE}")
  endif()
653

654 655
  # If we failed to extract any linker paths, we'll try using the -showme:libdirs option with the MPI compiler.
  # This will return a list of folders, not a set of flags!
656 657 658 659 660 661 662
  if (NOT MPI_ALL_LINK_PATHS)
    _MPI_check_compiler(${LANG} "-showme:libdirs" MPI_LIBDIRS_CMDLINE MPI_LIBDIRS_COMPILER_RETURN)
    if(MPI_LIBDIRS_COMPILER_RETURN)
      separate_arguments(MPI_ALL_LINK_PATHS NATIVE_COMMAND "${MPI_LIBDIRS_CMDLINE}")
    endif()
  endif()

663
  # We need to remove potential quotes and convert the paths to CMake syntax while resolving them, too.
664 665 666 667 668 669
  foreach(_MPI_LPATH IN LISTS MPI_ALL_LINK_PATHS)
    string(REPLACE "\"" "" _MPI_LPATH "${_MPI_LPATH}")
    get_filename_component(_MPI_LPATH "${_MPI_LPATH}" REALPATH)
    list(APPEND MPI_LINK_DIRECTORIES_WORK "${_MPI_LPATH}")
  endforeach()

670 671 672 673 674 675 676 677 678
  # Extract the set of libraries to link against from the link command line
  # This only makes sense if CMAKE_LINK_LIBRARY_FLAG is defined, i.e. a -lxxxx syntax is supported by the compiler.
  if(CMAKE_LINK_LIBRARY_FLAG)
    string(REGEX MATCHALL "(^| )${CMAKE_LINK_LIBRARY_FLAG}([^\" ]+|\"[^\"]+\")"
      MPI_LIBNAMES "${MPI_LINK_CMDLINE}")

    foreach(_MPI_LIB_NAME IN LISTS MPI_LIBNAMES)
      string(REGEX REPLACE "^ ?${CMAKE_LINK_LIBRARY_FLAG}" "" _MPI_LIB_NAME "${_MPI_LIB_NAME}")
      string(REPLACE "\"" "" _MPI_LIB_NAME "${_MPI_LIB_NAME}")
679
      list(APPEND MPI_LIB_NAMES_WORK "${_MPI_LIB_NAME}")
680 681
    endforeach()
  endif()
682

683 684 685 686 687 688 689 690 691
  # Treat linker objects given by full path, for example static libraries, import libraries
  # or shared libraries if there aren't any import libraries in use on the system.
  # Note that we do not consider CMAKE_<TYPE>_LIBRARY_PREFIX intentionally here: The linker will for a given file
  # decide how to link it based on file type, not based on a prefix like 'lib'.
  set(_MPI_LIB_NAME_REGEX "[^\" ]+${CMAKE_STATIC_LIBRARY_SUFFIX}|\"[^\"]+${CMAKE_STATIC_LIBRARY_SUFFIX}\"")
  if(DEFINED CMAKE_IMPORT_LIBRARY_SUFFIX)
    if(NOT ("${CMAKE_IMPORT_LIBRARY_SUFFIX}" STREQUAL "${CMAKE_STATIC_LIBRARY_SUFFIX}"))
      string(APPEND _MPI_LIB_NAME_REGEX "[^\" ]+${CMAKE_IMPORT_LIBRARY_SUFFIX}|\"[^\"]+${CMAKE_IMPORT_LIBRARY_SUFFIX}\"")
    endif()
692
  else()
693
    string(APPEND _MPI_LIB_NAME_REGEX "[^\" ]+${CMAKE_SHARED_LIBRARY_SUFFIX}|\"[^\"]+${CMAKE_SHARED_LIBRARY_SUFFIX}\"")
694
  endif()
695 696 697 698 699 700 701 702 703 704 705 706 707
  string(REPLACE "." "\\." _MPI_LIB_NAME_REGEX "${_MPI_LIB_NAME_REGEX}")

  string(REGEX MATCHALL "(^| )(${_MPI_LIB_NAME_REGEX})" MPI_LIBNAMES "${MPI_LINK_CMDLINE}")
  foreach(_MPI_LIB_NAME IN LISTS MPI_LIBNAMES)
    string(REGEX REPLACE "^ " "" _MPI_LIB_NAME "${_MPI_LIB_NAME}")
    string(REPLACE "\"" "" _MPI_LIB_NAME "${_MPI_LIB_NAME}")
    get_filename_component(_MPI_LIB_PATH "${_MPI_LIB_NAME}" DIRECTORY)
    if(NOT "${_MPI_LIB_PATH}" STREQUAL "")
      list(APPEND MPI_LIB_FULLPATHS_WORK "${_MPI_LIB_NAME}")
    else()
      list(APPEND MPI_LIB_NAMES_WORK "${_MPI_LIB_NAME}")
    endif()
  endforeach()
708

709 710 711
  # Save the explicitly given link directories
  set(MPI_LINK_DIRECTORIES_LEFTOVER "${MPI_LINK_DIRECTORIES_WORK}")

712 713 714 715 716
  # An MPI compiler wrapper could have its MPI libraries in the implictly
  # linked directories of the compiler itself.
  if(DEFINED CMAKE_${LANG}_IMPLICIT_LINK_DIRECTORIES)
    list(APPEND MPI_LINK_DIRECTORIES_WORK "${CMAKE_${LANG}_IMPLICIT_LINK_DIRECTORIES}")
  endif()
717

718 719 720 721 722 723 724 725 726 727 728 729
  # Determine full path names for all of the libraries that one needs
  # to link against in an MPI program
  unset(MPI_PLAIN_LIB_NAMES_WORK)
  foreach(_MPI_LIB_NAME IN LISTS MPI_LIB_NAMES_WORK)
    get_filename_component(_MPI_PLAIN_LIB_NAME "${_MPI_LIB_NAME}" NAME_WE)
    list(APPEND MPI_PLAIN_LIB_NAMES_WORK "${_MPI_PLAIN_LIB_NAME}")
    find_library(MPI_${_MPI_PLAIN_LIB_NAME}_LIBRARY
      NAMES "${_MPI_LIB_NAME}" "lib${_MPI_LIB_NAME}"
      HINTS ${MPI_LINK_DIRECTORIES_WORK}
      DOC "Location of the ${_MPI_PLAIN_LIB_NAME} library for MPI"
    )
    mark_as_advanced(MPI_${_MPI_PLAIN_LIB_NAME}_LIBRARY)
730 731 732 733 734 735 736 737 738
    # Remove the directory from the remainder list.
    if(MPI_${_MPI_PLAIN_LIB_NAME}_LIBRARY)
      get_filename_component(_MPI_TAKEN_DIRECTORY "${MPI_${_MPI_PLAIN_LIB_NAME}_LIBRARY}" DIRECTORY)
      list(REMOVE_ITEM MPI_LINK_DIRECTORIES_LEFTOVER "${_MPI_TAKEN_DIRECTORY}")
    endif()
  endforeach()

  # Add the link directories given explicitly that we haven't used back as linker directories.
  foreach(_MPI_LINK_DIRECTORY IN LISTS MPI_LINK_DIRECTORIES_LEFTOVER)
739 740 741 742 743
    file(TO_NATIVE_PATH "${_MPI_LINK_DIRECTORY}" _MPI_LINK_DIRECTORY_ACTUAL)
    string(FIND "${_MPI_LINK_DIRECTORY_ACTUAL}" " " _MPI_LINK_DIRECTORY_CONTAINS_SPACE)
    if(NOT _MPI_LINK_DIRECTORY_CONTAINS_SPACE EQUAL -1)
      set(_MPI_LINK_DIRECTORY_ACTUAL "\"${_MPI_LINK_DIRECTORY_ACTUAL}\"")
    endif()
744
    if(MPI_LINK_FLAGS_WORK)
745
      string(APPEND MPI_LINK_FLAGS_WORK " ${CMAKE_LIBRARY_PATH_FLAG}${_MPI_LINK_DIRECTORY_ACTUAL}")
746
    else()
747
      set(MPI_LINK_FLAGS_WORK "${CMAKE_LIBRARY_PATH_FLAG}${_MPI_LINK_DIRECTORY_ACTUAL}")
748
    endif()
749
  endforeach()
750

751 752 753 754 755
  # Deal with the libraries given with full path next
  unset(MPI_DIRECT_LIB_NAMES_WORK)
  foreach(_MPI_LIB_FULLPATH IN LISTS MPI_LIB_FULLPATHS_WORK)
    get_filename_component(_MPI_PLAIN_LIB_NAME "${_MPI_LIB_FULLPATH}" NAME_WE)
    list(APPEND MPI_DIRECT_LIB_NAMES_WORK "${_MPI_PLAIN_LIB_NAME}")
756
    set(MPI_${_MPI_PLAIN_LIB_NAME}_LIBRARY "${_MPI_LIB_FULLPATH}" CACHE FILEPATH "Location of the ${_MPI_PLAIN_LIB_NAME} library for MPI")
757 758
    mark_as_advanced(MPI_${_MPI_PLAIN_LIB_NAME}_LIBRARY)
  endforeach()
759
  # Directly linked objects should be linked first in case some generic linker flags are needed for them.
760 761 762
  if(MPI_DIRECT_LIB_NAMES_WORK)
    set(MPI_PLAIN_LIB_NAMES_WORK "${MPI_DIRECT_LIB_NAMES_WORK};${MPI_PLAIN_LIB_NAMES_WORK}")
  endif()
763

764 765 766 767 768 769 770 771 772 773
  # MPI might require pthread to work. The above mechanism wouldn't detect it, but we need to
  # link it in that case. -lpthread is covered by the normal library treatment on the other hand.
  if("${MPI_COMPILE_CMDLINE}" MATCHES "-pthread")
    list(APPEND MPI_COMPILE_OPTIONS_WORK "-pthread")
    if(MPI_LINK_FLAGS_WORK)
      string(APPEND MPI_LINK_FLAGS_WORK " -pthread")
    else()
      set(MPI_LINK_FLAGS_WORK "-pthread")
    endif()
  endif()
774

775 776 777 778 779 780 781 782 783 784
  if(MPI_${LANG}_EXTRA_COMPILE_DEFINITIONS)
    list(APPEND MPI_COMPILE_DEFINITIONS_WORK "${MPI_${LANG}_EXTRA_COMPILE_DEFINITIONS}")
  endif()
  if(MPI_${LANG}_EXTRA_COMPILE_OPTIONS)
    list(APPEND MPI_COMPILE_OPTIONS_WORK "${MPI_${LANG}_EXTRA_COMPILE_OPTIONS}")
  endif()
  if(MPI_${LANG}_EXTRA_LIB_NAMES)
    list(APPEND MPI_PLAIN_LIB_NAMES_WORK "${MPI_${LANG}_EXTRA_LIB_NAMES}")
  endif()

785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802
  # If we found MPI, set up all of the appropriate cache entries
  if(NOT MPI_${LANG}_COMPILE_OPTIONS)
    set(MPI_${LANG}_COMPILE_OPTIONS          ${MPI_COMPILE_OPTIONS_WORK}     CACHE STRING "MPI ${LANG} compilation options"            FORCE)
  endif()
  if(NOT MPI_${LANG}_COMPILE_DEFINITIONS)
    set(MPI_${LANG}_COMPILE_DEFINITIONS      ${MPI_COMPILE_DEFINITIONS_WORK} CACHE STRING "MPI ${LANG} compilation definitions"        FORCE)
  endif()
  if(NOT MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS)
    set(MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS  ${MPI_INCLUDE_DIRS_WORK}        CACHE STRING "MPI ${LANG} additional include directories" FORCE)
  endif()
  if(NOT MPI_${LANG}_LINK_FLAGS)
    set(MPI_${LANG}_LINK_FLAGS               ${MPI_LINK_FLAGS_WORK}          CACHE STRING "MPI ${LANG} linker flags"                   FORCE)
  endif()
  if(NOT MPI_${LANG}_LIB_NAMES)
    set(MPI_${LANG}_LIB_NAMES                ${MPI_PLAIN_LIB_NAMES_WORK}     CACHE STRING "MPI ${LANG} libraries to link against"      FORCE)
  endif()
  set(MPI_${LANG}_WRAPPER_FOUND TRUE PARENT_SCOPE)
endfunction()
803

804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822
function(_MPI_guess_settings LANG)
  set(MPI_GUESS_FOUND FALSE)
  # Currently only MSMPI and MPICH2 on Windows are supported, so we can skip this search if we're not targeting that.
  if(WIN32)
    # MSMPI

    # The environment variables MSMPI_INC and MSMPILIB32/64 are the only ways of locating the MSMPI_SDK,
    # which is installed separately from the runtime. Thus it's possible to have mpiexec but not MPI headers
    # or import libraries and vice versa.
    if(NOT MPI_GUESS_LIBRARY_NAME OR "${MPI_GUESS_LIBRARY_NAME}" STREQUAL "MSMPI")
      # We first attempt to locate the msmpi.lib. Should be find it, we'll assume that the MPI present is indeed
      # Microsoft MPI.
      if("${CMAKE_SIZEOF_VOID_P}" EQUAL 8)
        set(MPI_MSMPI_LIB_PATH "$ENV{MSMPI_LIB64}")
        set(MPI_MSMPI_INC_PATH_EXTRA "$ENV{MSMPI_INC}/x64")
      else()
        set(MPI_MSMPI_LIB_PATH "$ENV{MSMPI_LIB32}")
        set(MPI_MSMPI_INC_PATH_EXTRA "$ENV{MSMPI_INC}/x86")
      endif()
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      find_library(MPI_msmpi_LIBRARY
        NAMES msmpi
        HINTS ${MPI_MSMPI_LIB_PATH}
        DOC "Location of the msmpi library for Microsoft MPI")
      mark_as_advanced(MPI_msmpi_LIBRARY)

      if(MPI_msmpi_LIBRARY)
        # Next, we attempt to locate the MPI header. Note that for Fortran we know that mpif.h is a way
        # MSMPI can be used and therefore that header has to be present.
        if(NOT MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS)
          get_filename_component(MPI_MSMPI_INC_DIR "$ENV{MSMPI_INC}" REALPATH)
          set(MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS "${MPI_MSMPI_INC_DIR}" CACHE STRING "MPI ${LANG} additional include directories" FORCE)
          unset(MPI_MSMPI_INC_DIR)
837
        endif()
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        # For MSMPI, one can compile the MPI module by building the mpi.f90 shipped with the MSMPI SDK,
        # thus it might be present or provided by the user. Figuring out which is supported is done later on.
        # The PGI Fortran compiler for instance ships a prebuilt set of modules in its own include folder.
        # Should a user be employing PGI or have built its own set and provided it via cache variables, the
        # splitting routine would have located the module files.

        # For C and C++, we're done here (MSMPI does not ship the MPI-2 C++ bindings) - however, for Fortran
        # we need some extra library to glue Fortran support together:
        # MSMPI ships 2-4 Fortran libraries, each for different Fortran compiler behaviors. The library names
        # ending with a c are using the cdecl calling convention, whereas those ending with an s are for Fortran
        # implementations using stdcall. Therefore, the 64-bit MSMPI only ships those ending in 'c', whereas the 32-bit
        # has both variants available.
        # The second difference is the last but one letter, if it's an e(nd), the length of a string argument is
        # passed by the Fortran compiler after all other arguments on the parameter list, if it's an m(ixed),
        # it's passed immediately after the string address.

        # To summarize:
        #   - msmpifec: CHARACTER length passed after the parameter list and using cdecl calling convention
        #   - msmpifmc: CHARACTER length passed directly after string address and using cdecl calling convention
        #   - msmpifes: CHARACTER length passed after the parameter list and using stdcall calling convention
        #   - msmpifms: CHARACTER length passed directly after string address and using stdcall calling convention
        # 32-bit MSMPI ships all four libraries, 64-bit MSMPI ships only the first two.

        # As is, Intel Fortran and PGI Fortran both use the 'ec' variant of the calling convention, whereas
        # the old Compaq Visual Fortran compiler defaulted to the 'ms' version. It's possible to make Intel Fortran
        # use the CVF calling convention using /iface:cvf, but we assume - and this is also assumed in FortranCInterface -
        # this isn't the case. It's also possible to make CVF use the 'ec' variant, using /iface=(cref,nomixed_str_len_arg).

        # Our strategy is now to locate all libraries, but enter msmpifec into the LIB_NAMES array.
        # Should this not be adequate it's a straightforward way for a user to change the LIB_NAMES array and
        # have his library found. Still, this should not be necessary outside of exceptional cases, as reasoned.
        if ("${LANG}" STREQUAL "Fortran")
          set(MPI_MSMPI_CALLINGCONVS c)
          if("${CMAKE_SIZEOF_VOID_P}" EQUAL 4)
            list(APPEND MPI_MSMPI_CALLINGCONVS s)
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          endif()
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          foreach(mpistrlenpos IN ITEMS e m)
            foreach(mpicallingconv IN LISTS MPI_MSMPI_CALLINGCONVS)
              find_library(MPI_msmpif${mpistrlenpos}${mpicallingconv}_LIBRARY
                NAMES msmpif${mpistrlenpos}${mpicallingconv}
                HINTS "${MPI_MSMPI_LIB_PATH}"
                DOC "Location of the msmpi${mpistrlenpos}${mpicallingconv} library for Microsoft MPI")
              mark_as_advanced(MPI_msmpif${mpistrlenpos}${mpicallingconv}_LIBRARY)
            endforeach()
          endforeach()
          if(NOT MPI_${LANG}_LIB_NAMES)
            set(MPI_${LANG}_LIB_NAMES "msmpi;msmpifec" CACHE STRING "MPI ${LANG} libraries to link against" FORCE)
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          endif()

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          # At this point we're *not* done. MSMPI requires an additional include file for Fortran giving the value
          # of MPI_AINT. This file is called mpifptr.h located in the x64 and x86 subfolders, respectively.
          find_path(MPI_mpifptr_INCLUDE_DIR
            NAMES "mpifptr.h"
            HINTS "${MPI_MSMPI_INC_PATH_EXTRA}"
            DOC "Location of the mpifptr.h extra header for Microsoft MPI")
          if(NOT MPI_${LANG}_ADDITIONAL_INCLUDE_VARS)
            set(MPI_${LANG}_ADDITIONAL_INCLUDE_VARS "mpifptr" CACHE STRING "MPI ${LANG} additional include directory variables, given in the form MPI_<name>_INCLUDE_DIR." FORCE)
          endif()
          mark_as_advanced(MPI_${LANG}_ADDITIONAL_INCLUDE_VARS MPI_mpifptr_INCLUDE_DIR)
        else()
          if(NOT MPI_${LANG}_LIB_NAMES)
            set(MPI_${LANG}_LIB_NAMES "msmpi" CACHE STRING "MPI ${LANG} libraries to link against" FORCE)
          endif()
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        endif()
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        mark_as_advanced(MPI_${LANG}_LIB_NAMES)
        set(MPI_GUESS_FOUND TRUE)
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        if(_MPIEXEC_NOT_GIVEN)
          unset(MPIEXEC_EXECUTABLE CACHE)
        endif()

        find_program(MPIEXEC_EXECUTABLE
          NAMES mpiexec
          HINTS $ENV{MSMPI_BIN} "[HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\MPI;InstallRoot]/Bin"
          DOC "Executable for running MPI programs.")
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      endif()
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    endif()
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    # At this point there's not many MPIs that we could still consider.
    # OpenMPI 1.6.x and below supported Windows, but these ship compiler wrappers that still work.
    # The only other relevant MPI implementation without a wrapper is MPICH2, which had Windows support in 1.4.1p1 and older.
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    if(NOT MPI_GUESS_FOUND AND (NOT MPI_GUESS_LIBRARY_NAME OR "${MPI_GUESS_LIBRARY_NAME}" STREQUAL "MPICH2"))
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      set(MPI_MPICH_PREFIX_PATHS
        "$ENV{ProgramW6432}/MPICH2/lib"
        "[HKEY_LOCAL_MACHINE\\SOFTWARE\\MPICH\\SMPD;binary]/../lib"
        "[HKEY_LOCAL_MACHINE\\SOFTWARE\\MPICH2;Path]/lib"
      )
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      # All of C, C++ and Fortran will need mpi.lib, so we'll look for this first
      find_library(MPI_mpi_LIBRARY
        NAMES mpi
        HINTS ${MPI_MPICH_PREFIX_PATHS})
      mark_as_advanced(MPI_mpi_LIBRARY)
      # If we found mpi.lib, we detect the rest of MPICH2
      if(MPI_mpi_LIBRARY)
        set(MPI_MPICH_LIB_NAMES "mpi")
        # If MPI-2 C++ bindings are requested, we need to locate cxx.lib as well.
        # Otherwise, MPICH_SKIP_MPICXX will be defined and these bindings aren't needed.
        if("${LANG}" STREQUAL "CXX" AND NOT MPI_CXX_SKIP_MPICXX)
          find_library(MPI_cxx_LIBRARY
            NAMES cxx
            HINTS ${MPI_MPICH_PREFIX_PATHS})
          mark_as_advanced(MPI_cxx_LIBRARY)
          list(APPEND MPI_MPICH_LIB_NAMES "cxx")
        # For Fortran, MPICH2 provides three different libraries:
        #   fmpich2.lib which uses uppercase symbols and cdecl,
        #   fmpich2s.lib which uses uppercase symbols and stdcall (32-bit only),
        #   fmpich2g.lib which uses lowercase symbols with double underscores and cdecl.
        # fmpich2s.lib would be useful for Compaq Visual Fortran, fmpich2g.lib has to be used with GNU g77 and is also
        # provided in the form of an .a archive for MinGW and Cygwin. From our perspective, fmpich2.lib is the only one
        # we need to try, and if it doesn't work with the given Fortran compiler we'd find out later on during validation
        elseif("${LANG}" STREQUAL "Fortran")
          find_library(MPI_fmpich2_LIBRARY
            NAMES fmpich2
            HINTS ${MPI_MPICH_PREFIX_PATHS})
          find_library(MPI_fmpich2s_LIBRARY
            NAMES fmpich2s
            HINTS ${MPI_MPICH_PREFIX_PATHS})
          find_library(MPI_fmpich2g_LIBRARY
            NAMES fmpich2g
            HINTS ${MPI_MPICH_PREFIX_PATHS})
          mark_as_advanced(MPI_fmpich2_LIBRARY MPI_fmpich2s_LIBRARY MPI_fmpich2g_LIBRARY)
          list(APPEND MPI_MPICH_LIB_NAMES "fmpich2")
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        endif()

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        if(NOT MPI_${LANG}_LIB_NAMES)
          set(MPI_${LANG}_LIB_NAMES "${MPI_MPICH_LIB_NAMES}" CACHE STRING "MPI ${LANG} libraries to link against" FORCE)
        endif()
        unset(MPI_MPICH_LIB_NAMES)

        if(NOT MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS)
          # For MPICH2, the include folder would be in ../include relative to the library folder.
          get_filename_component(MPI_MPICH_ROOT_DIR "${MPI_mpi_LIBRARY}" DIRECTORY)
          get_filename_component(MPI_MPICH_ROOT_DIR "${MPI_MPICH_ROOT_DIR}" DIRECTORY)
          if(IS_DIRECTORY "${MPI_MPICH_ROOT_DIR}/include")
            set(MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS "${MPI_MPICH_ROOT_DIR}/include" CACHE STRING "MPI ${LANG} additional include directory variables, given in the form MPI_<name>_INCLUDE_DIR." FORCE)
          endif()
          unset(MPI_MPICH_ROOT_DIR)
        endif()
        set(MPI_GUESS_FOUND TRUE)
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        if(_MPIEXEC_NOT_GIVEN)
          unset(MPIEXEC_EXECUTABLE CACHE)
        endif()

        find_program(MPIEXEC_EXECUTABLE
          NAMES ${_MPIEXEC_NAMES}
          HINTS "$ENV{ProgramW6432}/MPICH2/bin"
                "[HKEY_LOCAL_MACHINE\\SOFTWARE\\MPICH\\SMPD;binary]"
                "[HKEY_LOCAL_MACHINE\\SOFTWARE\\MPICH2;Path]/bin"
          DOC "Executable for running MPI programs.")
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      endif()
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      unset(MPI_MPICH_PREFIX_PATHS)
    endif()
  endif()
  set(MPI_${LANG}_GUESS_FOUND "${MPI_GUESS_FOUND}" PARENT_SCOPE)
endfunction()

function(_MPI_adjust_compile_definitions LANG)
  if("${LANG}" STREQUAL "CXX")
    # To disable the C++ bindings, we need to pass some definitions since the mpi.h header has to deal with both C and C++
    # bindings in MPI-2.
    if(MPI_CXX_SKIP_MPICXX AND NOT MPI_${LANG}_COMPILE_DEFINITIONS MATCHES "SKIP_MPICXX")
      # MPICH_SKIP_MPICXX is being used in MPICH and derivatives like MVAPICH or Intel MPI
      # OMPI_SKIP_MPICXX is being used in Open MPI
      # _MPICC_H is being used for IBM Platform MPI
      list(APPEND MPI_${LANG}_COMPILE_DEFINITIONS "MPICH_SKIP_MPICXX" "OMPI_SKIP_MPICXX" "_MPICC_H")
      set(MPI_${LANG}_COMPILE_DEFINITIONS "${MPI_${LANG}_COMPILE_DEFINITIONS}" CACHE STRING "MPI ${LANG} compilation definitions" FORCE)
1007
    endif()
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  endif()
endfunction()
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macro(_MPI_assemble_libraries LANG)
  set(MPI_${LANG}_LIBRARIES "")
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  # Only for libraries do we need to check whether the compiler's linking stage is separate.
  if(NOT "${MPI_${LANG}_COMPILER}" STREQUAL "${CMAKE_${LANG}_COMPILER}" OR NOT MPI_${LANG}_WORKS_IMPLICIT)
    foreach(mpilib IN LISTS MPI_${LANG}_LIB_NAMES)
      list(APPEND MPI_${LANG}_LIBRARIES ${MPI_${mpilib}_LIBRARY})
    endforeach()
  endif()
1019
endmacro()
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macro(_MPI_assemble_include_dirs LANG)
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  if("${MPI_${LANG}_COMPILER}" STREQUAL "${CMAKE_${LANG}_COMPILER}")
    set(MPI_${LANG}_INCLUDE_DIRS "")
  else()
    set(MPI_${LANG}_INCLUDE_DIRS "${MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS}")
    if("${LANG}" MATCHES "(C|CXX)")
      if(MPI_${LANG}_HEADER_DIR)
        list(APPEND MPI_${LANG}_INCLUDE_DIRS "${MPI_${LANG}_HEADER_DIR}")
      endif()
    else() # Fortran
      if(MPI_${LANG}_F77_HEADER_DIR)
        list(APPEND MPI_${LANG}_INCLUDE_DIRS "${MPI_${LANG}_F77_HEADER_DIR}")
      endif()
      if(MPI_${LANG}_MODULE_DIR AND NOT "${MPI_${LANG}_MODULE_DIR}" IN_LIST MPI_${LANG}_INCLUDE_DIRS)
        list(APPEND MPI_${LANG}_INCLUDE_DIRS "${MPI_${LANG}_MODULE_DIR}")
      endif()
1037
    endif()
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    if(MPI_${LANG}_ADDITIONAL_INCLUDE_VARS)
      foreach(MPI_ADDITIONAL_INC_DIR IN LISTS MPI_${LANG}_ADDITIONAL_INCLUDE_VARS)
        list(APPEND MPI_${LANG}_INCLUDE_DIRS "${MPI_${MPI_ADDITIONAL_INC_DIR}_INCLUDE_DIR}")
      endforeach()
1042
    endif()
1043
  endif()
1044
endmacro()
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1046
function(_MPI_split_include_dirs LANG)
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  if("${MPI_${LANG}_COMPILER}" STREQUAL "${CMAKE_${LANG}_COMPILER}")
    return()
  endif()
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  # Backwards compatibility: Search INCLUDE_PATH if given.
  if(MPI_${LANG}_INCLUDE_PATH)
    list(APPEND MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS "${MPI_${LANG}_INCLUDE_PATH}")
1053
  endif()
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  # We try to find the headers/modules among those paths (and system paths)
  # For C/C++, we just need to have a look for mpi.h.
  if("${LANG}" MATCHES "(C|CXX)")
    find_path(MPI_${LANG}_HEADER_DIR "mpi.h"
      HINTS ${MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS}
    )
    mark_as_advanced(MPI_${LANG}_HEADER_DIR)
    if(MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS)
      list(REMOVE_ITEM MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS "${MPI_${LANG}_HEADER_DIR}")
    endif()
  # Fortran is more complicated here: An implementation could provide
  # any of the Fortran 77/90/2008 APIs for MPI. For example, MSMPI
  # only provides Fortran 77 and - if mpi.f90 is built - potentially
  # a Fortran 90 module.
  elseif("${LANG}" STREQUAL "Fortran")
    find_path(MPI_${LANG}_F77_HEADER_DIR "mpif.h"
      HINTS ${MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS}
    )
    find_path(MPI_${LANG}_MODULE_DIR
      NAMES "mpi.mod" "mpi_f08.mod"
      HINTS ${MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS}
    )
    if(MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS)
      list(REMOVE_ITEM MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS
        "${MPI_${LANG}_F77_HEADER_DIR}"
        "${MPI_${LANG}_MODULE_DIR}"
      )
    endif()
    mark_as_advanced(MPI_${LANG}_F77_HEADER_DIR MPI_${LANG}_MODULE_DIR)
  endif()
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  # Remove duplicates and default system directories from the list.
  if(MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS)
    list(REMOVE_DUPLICATES MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS)
    foreach(MPI_IMPLICIT_INC_DIR IN LISTS CMAKE_${LANG}_IMPLICIT_LINK_DIRECTORIES)
      list(REMOVE_ITEM MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS ${MPI_IMPLICIT_INC_DIR})
    endforeach()
  endif()
1092
  set(MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS ${MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS} CACHE STRING "MPI ${LANG} additional include directories" FORCE)
1093 1094
endfunction()

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macro(_MPI_create_imported_target LANG)
  if(NOT TARGET MPI::MPI_${LANG})
    add_library(MPI::MPI_${LANG} INTERFACE IMPORTED)
  endif()
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  set_property(TARGET MPI::MPI_${LANG} PROPERTY INTERFACE_COMPILE_OPTIONS "${MPI_${LANG}_COMPILE_OPTIONS}")
  set_property(TARGET MPI::MPI_${LANG} PROPERTY INTERFACE_COMPILE_DEFINITIONS "${MPI_${LANG}_COMPILE_DEFINITIONS}")

  set_property(TARGET MPI::MPI_${LANG} PROPERTY INTERFACE_LINK_LIBRARIES "")
  if(MPI_${LANG}_LINK_FLAGS)
    set_property(TARGET MPI::MPI_${LANG} APPEND PROPERTY INTERFACE_LINK_LIBRARIES "${MPI_${LANG}_LINK_FLAGS}")
  endif()
  # If the compiler links MPI implicitly, no libraries will be found as they're contained within
  # CMAKE_<LANG>_IMPLICIT_LINK_LIBRARIES already.
  if(MPI_${LANG}_LIBRARIES)
    set_property(TARGET MPI::MPI_${LANG} APPEND PROPERTY INTERFACE_LINK_LIBRARIES "${MPI_${LANG}_LIBRARIES}")
  endif()
  # Given the new design of FindMPI, INCLUDE_DIRS will always be located, even under implicit linking.
  set_property(TARGET MPI::MPI_${LANG} PROPERTY INTERFACE_INCLUDE_DIRECTORIES "${MPI_${LANG}_INCLUDE_DIRS}")
endmacro()

function(_MPI_try_staged_settings LANG MPI_TEST_FILE_NAME MODE RUN_BINARY)
  set(WORK_DIR "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/FindMPI")
  set(SRC_DIR "${CMAKE_ROOT}/Modules/FindMPI")
  set(BIN_FILE "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/FindMPI/${MPI_TEST_FILE_NAME}_${LANG}.bin")
  unset(MPI_TEST_COMPILE_DEFINITIONS)
  if("${LANG}" STREQUAL "Fortran")
    if("${MODE}" STREQUAL "F90_MODULE")
      set(MPI_Fortran_INCLUDE_LINE "use mpi\n      implicit none")
    elseif("${MODE}" STREQUAL "F08_MODULE")
      set(MPI_Fortran_INCLUDE_LINE "use mpi_f08\n      implicit none")
    else() # F77 header
      set(MPI_Fortran_INCLUDE_LINE "implicit none\n      include 'mpif.h'")
    endif()
    configure_file("${SRC_DIR}/${MPI_TEST_FILE_NAME}.f90.in" "${WORK_DIR}/${MPI_TEST_FILE_NAME}.f90" @ONLY)
    set(MPI_TEST_SOURCE_FILE "${WORK_DIR}/${MPI_TEST_FILE_NAME}.f90")
  elseif("${LANG}" STREQUAL "CXX")
    configure_file("${SRC_DIR}/${MPI_TEST_FILE_NAME}.c" "${WORK_DIR}/${MPI_TEST_FILE_NAME}.cpp" COPYONLY)
    set(MPI_TEST_SOURCE_FILE "${WORK_DIR}/${MPI_TEST_FILE_NAME}.cpp")
    if("${MODE}" STREQUAL "TEST_MPICXX")
      set(MPI_TEST_COMPILE_DEFINITIONS TEST_MPI_MPICXX)
1136
    endif()
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  else() # C
    set(MPI_TEST_SOURCE_FILE "${SRC_DIR}/${MPI_TEST_FILE_NAME}.c")
  endif()
  if(RUN_BINARY)
    try_run(MPI_RUN_RESULT_${LANG}_${MPI_TEST_FILE_NAME}_${MODE} MPI_RESULT_${LANG}_${MPI_TEST_FILE_NAME}_${MODE}
     "${CMAKE_BINARY_DIR}" SOURCES "${MPI_TEST_SOURCE_FILE}"
      COMPILE_DEFINITIONS ${MPI_TEST_COMPILE_DEFINITIONS}
      LINK_LIBRARIES MPI::MPI_${LANG}
      RUN_OUTPUT_VARIABLE MPI_RUN_OUTPUT_${LANG}_${MPI_TEST_FILE_NAME}_${MODE})
    set(MPI_RUN_OUTPUT_${LANG}_${MPI_TEST_FILE_NAME}_${MODE} "${MPI_RUN_OUTPUT_${LANG}_${MPI_TEST_FILE_NAME}_${MODE}}" PARENT_SCOPE)
  else()
    try_compile(MPI_RESULT_${LANG}_${MPI_TEST_FILE_NAME}_${MODE}
      "${CMAKE_BINARY_DIR}" SOURCES "${MPI_TEST_SOURCE_FILE}"
      COMPILE_DEFINITIONS ${MPI_TEST_COMPILE_DEFINITIONS}
      LINK_LIBRARIES MPI::MPI_${LANG}
      COPY_FILE "${BIN_FILE}")
  endif()
1154 1155
endfunction()

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macro(_MPI_check_lang_works LANG)
  # For Fortran we may have by the MPI-3 standard an implementation that provides:
  #   - the mpi_f08 module
  #   - *both*, the mpi module and 'mpif.h'
  # Since older MPI standards (MPI-1) did not define anything but 'mpif.h', we need to check all three individually.
  if( NOT MPI_${LANG}_WORKS )
    if("${LANG}" STREQUAL "Fortran")
      set(MPI_Fortran_INTEGER_LINE "(kind=MPI_INTEGER_KIND)")
      _MPI_try_staged_settings(${LANG} test_mpi F77_HEADER FALSE)
      _MPI_try_staged_settings(${LANG} test_mpi F90_MODULE FALSE)
      _MPI_try_staged_settings(${LANG} test_mpi F08_MODULE FALSE)

      set(MPI_${LANG}_WORKS FALSE)

      foreach(mpimethod IN ITEMS F77_HEADER F08_MODULE F90_MODULE)
        if(MPI_RESULT_${LANG}_test_mpi_${mpimethod})
          set(MPI_${LANG}_WORKS TRUE)
          set(MPI_${LANG}_HAVE_${mpimethod} TRUE)
        else()
          set(MPI_${LANG}_HAVE_${mpimethod} FALSE)
        endif()
      endforeach()
      # MPI-1 versions had no MPI_INTGER_KIND defined, so we need to try without it.
      # However, MPI-1 also did not define the Fortran 90 and 08 modules, so we only try the F77 header.
      unset(MPI_Fortran_INTEGER_LINE)
      if(NOT MPI_${LANG}_WORKS)
        _MPI_try_staged_settings(${LANG} test_mpi F77_HEADER_NOKIND FALSE)
        if(MPI_RESULT_${LANG}_test_mpi_F77_HEADER_NOKIND)
          set(MPI_${LANG}_WORKS TRUE)
          set(MPI_${LANG}_HAVE_F77_HEADER TRUE)
        endif()
      endif()
    else()
      _MPI_try_staged_settings(${LANG} test_mpi normal FALSE)
      # If 'test_mpi' built correctly, we've found valid MPI settings. There might not be MPI-2 C++ support, but there can't
      # be MPI-2 C++ support without the C bindings being present, so checking for them is sufficient.
      set(MPI_${LANG}_WORKS "${MPI_RESULT_${LANG}_test_mpi_normal}")
    endif()
  endif()
endmacro()

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# Some systems install various MPI implementations in separate folders in some MPI prefix
# This macro enumerates all such subfolders and adds them to the list of hints that will be searched.
macro(MPI_search_mpi_prefix_folder PREFIX_FOLDER)
  if(EXISTS "${PREFIX_FOLDER}")
    file(GLOB _MPI_folder_children RELATIVE "${PREFIX_FOLDER}" "${PREFIX_FOLDER}/*")
    foreach(_MPI_folder_child IN LISTS _MPI_folder_children)
      if(IS_DIRECTORY "${PREFIX_FOLDER}/${_MPI_folder_child}")
        list(APPEND MPI_HINT_DIRS "${PREFIX_FOLDER}/${_MPI_folder_child}")
      endif()
    endforeach()
  endif()
endmacro()

set(MPI_HINT_DIRS ${MPI_HOME} $ENV{MPI_HOME} $ENV{I_MPI_ROOT})
if("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "Linux")
  # SUSE Linux Enterprise Server stores its MPI implementations under /usr/lib64/mpi/gcc/<name>
  # We enumerate the subfolders and append each as a prefix
  MPI_search_mpi_prefix_folder("/usr/lib64/mpi/gcc")
elseif("${CMAKE_HOST_SYSTEM_NAME}" STREQUAL "FreeBSD")
  # FreeBSD ships mpich under the normal system paths - but available openmpi implementations
  # will be found in /usr/local/mpi/<name>
1218
  MPI_search_mpi_prefix_folder("/usr/local/mpi")
1219 1220
endif()

1221 1222 1223
# Most MPI distributions have some form of mpiexec or mpirun which gives us something we can look for.
# The MPI standard does not mandate the existence of either, but instead only makes requirements if a distribution
# ships an mpiexec program (mpirun executables are not regulated by the standard).
1224 1225 1226 1227 1228 1229 1230 1231 1232

# We defer searching for mpiexec binaries belonging to guesses until later. By doing so, mismatches between mpiexec
# and the MPI we found should be reduced.
if(NOT MPIEXEC_EXECUTABLE)
  set(_MPIEXEC_NOT_GIVEN TRUE)
else()
  set(_MPIEXEC_NOT_GIVEN FALSE)
endif()

1233 1234
find_program(MPIEXEC_EXECUTABLE
  NAMES ${_MPIEXEC_NAMES}
1235 1236
  PATH_SUFFIXES bin sbin
  HINTS ${MPI_HINT_DIRS}
1237
  DOC "Executable for running MPI programs.")
1238 1239 1240

# call get_filename_component twice to remove mpiexec and the directory it exists in (typically bin).
# This gives us a fairly reliable base directory to search for /bin /lib and /include from.
1241
get_filename_component(_MPI_BASE_DIR "${MPIEXEC_EXECUTABLE}" PATH)
1242
get_filename_component(_MPI_BASE_DIR "${_MPI_BASE_DIR}" PATH)
1243

1244 1245
# According to the MPI standard, section 8.8 -n is a guaranteed, and the only guaranteed way to
# launch an MPI process using mpiexec if such a program exists.
1246 1247 1248
set(MPIEXEC_NUMPROC_FLAG "-n"  CACHE STRING "Flag used by MPI to specify the number of processes for mpiexec; the next option will be the number of processes.")
set(MPIEXEC_PREFLAGS     ""    CACHE STRING "These flags will be directly before the executable that is being run by mpiexec.")
set(MPIEXEC_POSTFLAGS    ""    CACHE STRING "These flags will be placed after all flags passed to mpiexec.")
1249

1250 1251
# Set the number of processes to the physical processor count
cmake_host_system_information(RESULT _MPIEXEC_NUMPROCS QUERY NUMBER_OF_PHYSICAL_CORES)
1252
set(MPIEXEC_MAX_NUMPROCS "${_MPIEXEC_NUMPROCS}" CACHE STRING "Maximum number of processors available to run MPI applications.")
1253
unset(_MPIEXEC_NUMPROCS)
1254
mark_as_advanced(MPIEXEC_EXECUTABLE MPIEXEC_NUMPROC_FLAG MPIEXEC_PREFLAGS MPIEXEC_POSTFLAGS MPIEXEC_MAX_NUMPROCS)
1255 1256 1257 1258

#=============================================================================
# Backward compatibility input hacks.  Propagate the FindMPI hints to C and
# CXX if the respective new versions are not defined.  Translate the old
1259
# MPI_LIBRARY and MPI_EXTRA_LIBRARY to respective MPI_${LANG}_LIBRARIES.
1260 1261 1262
#
# Once we find the new variables, we translate them back into their old
# equivalents below.
1263 1264 1265 1266 1267 1268 1269 1270 1271
if(NOT MPI_IGNORE_LEGACY_VARIABLES)
  foreach (LANG IN ITEMS C CXX)
    # Old input variables.
    set(_MPI_OLD_INPUT_VARS COMPILER COMPILE_FLAGS INCLUDE_PATH LINK_FLAGS)

    # Set new vars based on their old equivalents, if the new versions are not already set.
    foreach (var ${_MPI_OLD_INPUT_VARS})
      if (NOT MPI_${LANG}_${var} AND MPI_${var})
        set(MPI_${LANG}_${var} "${MPI_${var}}")
1272 1273 1274
      endif()
    endforeach()

1275 1276 1277 1278 1279 1280 1281
    # Chop the old compile flags into options and definitions

    unset(MPI_${LANG}_EXTRA_COMPILE_DEFINITIONS)
    unset(MPI_${LANG}_EXTRA_COMPILE_OPTIONS)
    if(MPI_${LANG}_COMPILE_FLAGS)
      separate_arguments(MPI_SEPARATE_FLAGS NATIVE_COMMAND "${MPI_${LANG}_COMPILE_FLAGS}")
      foreach(_MPI_FLAG IN LISTS MPI_SEPARATE_FLAGS)
1282
        if("${_MPI_FLAG}" MATCHES "^ *-D([^ ]+)")
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310
          list(APPEND MPI_${LANG}_EXTRA_COMPILE_DEFINITIONS "${CMAKE_MATCH_1}")
        else()
          list(APPEND MPI_${LANG}_EXTRA_COMPILE_OPTIONS "${_MPI_FLAG}")
        endif()
      endforeach()
      unset(MPI_SEPARATE_FLAGS)
    endif()

    # If a list of libraries was given, we'll split it into new-style cache variables
    unset(MPI_${LANG}_EXTRA_LIB_NAMES)
    if(NOT MPI_${LANG}_LIB_NAMES)
      foreach(_MPI_LIB IN LISTS MPI_${LANG}_LIBRARIES MPI_LIBRARY MPI_EXTRA_LIBRARY)
        if(_MPI_LIB)
          get_filename_component(_MPI_PLAIN_LIB_NAME "${_MPI_LIB}" NAME_WE)
          get_filename_component(_MPI_LIB_NAME "${_MPI_LIB}" NAME)
          get_filename_component(_MPI_LIB_DIR "${_MPI_LIB}" DIRECTORY)
          list(APPEND MPI_${LANG}_EXTRA_LIB_NAMES "${_MPI_PLAIN_LIB_NAME}")
          find_library(MPI_${_MPI_PLAIN_LIB_NAME}_LIBRARY
            NAMES "${_MPI_LIB_NAME}" "lib${_MPI_LIB_NAME}"
            HINTS ${_MPI_LIB_DIR} $ENV{MPI_LIB}
            DOC "Location of the ${_MPI_PLAIN_LIB_NAME} library for MPI"
          )
          mark_as_advanced(MPI_${_MPI_PLAIN_LIB_NAME}_LIBRARY)
        endif()
      endforeach()
    endif()
  endforeach()
endif()
1311 1312
#=============================================================================

1313 1314 1315 1316 1317
unset(MPI_VERSION)
unset(MPI_VERSION_MAJOR)
unset(MPI_VERSION_MINOR)

unset(_MPI_MIN_VERSION)
1318

1319 1320 1321 1322 1323
# If the user specified a library name we assume they prefer that library over a wrapper. If not, they can disable skipping manually.
if(NOT DEFINED MPI_SKIP_COMPILER_WRAPPER AND MPI_GUESS_LIBRARY_NAME)
  set(MPI_SKIP_COMPILER_WRAPPER TRUE)
endif()

1324
# This loop finds the compilers and sends them off for interrogation.
1325
foreach(LANG IN ITEMS C CXX Fortran)
1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343
  if(CMAKE_${LANG}_COMPILER_LOADED)
    if(NOT MPI_FIND_COMPONENTS)
      set(_MPI_FIND_${LANG} TRUE)
    elseif( ${LANG} IN_LIST MPI_FIND_COMPONENTS)
      set(_MPI_FIND_${LANG} TRUE)
    elseif( ${LANG} STREQUAL CXX AND NOT MPI_CXX_SKIP_MPICXX AND MPICXX IN_LIST MPI_FIND_COMPONENTS )
      set(_MPI_FIND_${LANG} TRUE)
    else()
      set(_MPI_FIND_${LANG} FALSE)
    endif()
  else()
    set(_MPI_FIND_${LANG} FALSE)
  endif()
  if(_MPI_FIND_${LANG})
    if( ${LANG} STREQUAL CXX AND NOT MPICXX IN_LIST MPI_FIND_COMPONENTS )
      set(MPI_CXX_SKIP_MPICXX FALSE CACHE BOOL "If true, the MPI-2 C++ bindings are disabled using definitions.")
      mark_as_advanced(MPI_CXX_SKIP_MPICXX)
    endif()
1344
    if(NOT (MPI_${LANG}_LIB_NAMES AND (MPI_${LANG}_INCLUDE_PATH OR MPI_${LANG}_INCLUDE_DIRS OR MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS)))
1345 1346
      set(MPI_${LANG}_TRIED_IMPLICIT FALSE)
      set(MPI_${LANG}_WORKS_IMPLICIT FALSE)
1347 1348 1349 1350 1351 1352 1353 1354 1355
      if(NOT MPI_${LANG}_COMPILER AND NOT MPI_ASSUME_NO_BUILTIN_MPI)
        # Should the imported targets be empty, we effectively try whether the compiler supports MPI on its own, which is the case on e.g.
        # Cray PrgEnv.
        _MPI_create_imported_target(${LANG})
        _MPI_check_lang_works(${LANG})

        # If the compiler can build MPI code on its own, it functions as an MPI compiler and we'll set the variable to point to it.
        if(MPI_${LANG}_WORKS)
          set(MPI_${LANG}_COMPILER "${CMAKE_${LANG}_COMPILER}" CACHE FILEPATH "MPI compiler for ${LANG}" FORCE)
1356
          set(MPI_${LANG}_WORKS_IMPLICIT TRUE)
1357
        endif()
1358
        set(MPI_${LANG}_TRIED_IMPLICIT TRUE)
1359 1360
      endif()

1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386
      if(NOT "${MPI_${LANG}_COMPILER}" STREQUAL "${CMAKE_${LANG}_COMPILER}" OR NOT MPI_${LANG}_WORKS)
        set(MPI_${LANG}_WRAPPER_FOUND FALSE)
        set(MPI_PINNED_COMPILER FALSE)

        if(NOT MPI_SKIP_COMPILER_WRAPPER)
          if(MPI_${LANG}_COMPILER)
            # If the user supplies a compiler *name* instead of an absolute path, assume that we need to find THAT compiler.
            if (NOT IS_ABSOLUTE "${MPI_${LANG}_COMPILER}")
              # Get rid of our default list of names and just search for the name the user wants.
              set(_MPI_${LANG}_COMPILER_NAMES "${MPI_${LANG}_COMPILER}")
              unset(MPI_${LANG}_COMPILER CACHE)
            endif()
            # If the user specifies a compiler, we don't want to try to search libraries either.
            set(MPI_PINNED_COMPILER TRUE)
          endif()

          # If we have an MPI base directory, we'll try all compiler names in that one first.
          # This should prevent mixing different MPI environments
          if(_MPI_BASE_DIR)
            find_program(MPI_${LANG}_COMPILER
              NAMES  ${_MPI_${LANG}_COMPILER_NAMES}
              PATH_SUFFIXES bin sbin
              HINTS  ${_MPI_BASE_DIR}
              NO_DEFAULT_PATH
              DOC    "MPI compiler for ${LANG}"
            )
1387 1388
          endif()

1389 1390
          # If the base directory did not help (for example because the mpiexec isn't in the same directory as the compilers),
          # we shall try searching in the default paths.
1391 1392 1393 1394 1395 1396
          find_program(MPI_${LANG}_COMPILER
            NAMES  ${_MPI_${LANG}_COMPILER_NAMES}
            PATH_SUFFIXES bin sbin
            DOC    "MPI compiler for ${LANG}"
          )

1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417
          if("${MPI_${LANG}_COMPILER}" STREQUAL "${CMAKE_${LANG}_COMPILER}")
            set(MPI_PINNED_COMPILER TRUE)

            # If we haven't made the implicit compiler test yet, perform it now.
            if(NOT MPI_${LANG}_TRIED_IMPLICIT)
              _MPI_create_imported_target(${LANG})
              _MPI_check_lang_works(${LANG})
            endif()

            # Should the MPI compiler not work implicitly for MPI, still interrogate it.
            # Otherwise, MPI compilers for which CMake has separate linking stages, e.g. Intel MPI on Windows where link.exe is being used
            # directly during linkage instead of CMAKE_<LANG>_COMPILER will not work.
            if(NOT MPI_${LANG}_WORKS)
              set(MPI_${LANG}_WORKS_IMPLICIT FALSE)
              _MPI_interrogate_compiler(${LANG})
            else()
              set(MPI_${LANG}_WORKS_IMPLICIT TRUE)
            endif()
          elseif(MPI_${LANG}_COMPILER)
            _MPI_interrogate_compiler(${LANG})
          endif()
1418 1419
        endif()

1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434
        if(NOT MPI_PINNED_COMPILER AND NOT MPI_${LANG}_WRAPPER_FOUND)
          # If MPI_PINNED_COMPILER wasn't given, and the MPI compiler we potentially found didn't work, we withdraw it.
          set(MPI_${LANG}_COMPILER "MPI_${LANG}_COMPILER-NOTFOUND" CACHE FILEPATH "MPI compiler for ${LANG}" FORCE)
          if(NOT MPI_SKIP_GUESSING)
            # For C++, we may use the settings for C. Should a given compiler wrapper for C++ not exist, but one for C does, we copy over the
            # settings for C. An MPI distribution that is in this situation would be IBM Platform MPI.
            if("${LANG}" STREQUAL "CXX" AND MPI_C_WRAPPER_FOUND)
              set(MPI_${LANG}_COMPILE_OPTIONS          ${MPI_C_COMPILE_OPTIONS}     CACHE STRING "MPI ${LANG} compilation options"           )
              set(MPI_${LANG}_COMPILE_DEFINITIONS      ${MPI_C_COMPILE_DEFINITIONS} CACHE STRING "MPI ${LANG} compilation definitions"       )
              set(MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS  ${MPI_C_INCLUDE_DIRS}        CACHE STRING "MPI ${LANG} additional include directories")
              set(MPI_${LANG}_LINK_FLAGS               ${MPI_C_LINK_FLAGS}          CACHE STRING "MPI ${LANG} linker flags"                  )
              set(MPI_${LANG}_LIB_NAMES                ${MPI_C_LIB_NAMES}           CACHE STRING "MPI ${LANG} libraries to link against"     )
            else()
              _MPI_guess_settings(${LANG})
            endif()
1435
          endif()
1436 1437
        endif()
      endif()
1438 1439
    endif()

1440
    _MPI_split_include_dirs(${LANG})
1441 1442 1443
    _MPI_assemble_include_dirs(${LANG})
    _MPI_assemble_libraries(${LANG})

1444 1445 1446
    _MPI_adjust_compile_definitions(${LANG})
    # We always create imported targets even if they're empty
    _MPI_create_imported_target(${LANG})
1447

1448 1449
    if(NOT MPI_${LANG}_WORKS)
      _MPI_check_lang_works(${LANG})
1450
    endif()
1451

1452 1453 1454 1455 1456
    # Next, we'll initialize the MPI variables that have not been previously set.
    set(MPI_${LANG}_COMPILE_OPTIONS          "" CACHE STRING "MPI ${LANG} compilation flags"             )
    set(MPI_${LANG}_COMPILE_DEFINITIONS      "" CACHE STRING "MPI ${LANG} compilation definitions"       )
    set(MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS  "" CACHE STRING "MPI ${LANG} additional include directories")
    set(MPI_${LANG}_LINK_FLAGS               "" CACHE STRING "MPI ${LANG} linker flags"                  )
1457 1458 1459
    if(NOT MPI_${LANG}_COMPILER STREQUAL CMAKE_${LANG}_COMPILER)
      set(MPI_${LANG}_LIB_NAMES                "" CACHE STRING "MPI ${LANG} libraries to link against"   )
    endif()
1460 1461 1462 1463 1464 1465
    mark_as_advanced(MPI_${LANG}_COMPILE_OPTIONS MPI_${LANG}_COMPILE_DEFINITIONS MPI_${LANG}_LINK_FLAGS
      MPI_${LANG}_LIB_NAMES MPI_${LANG}_ADDITIONAL_INCLUDE_DIRS MPI_${LANG}_COMPILER)

    # If we've found MPI, then we'll perform additional analysis: Determine the MPI version, MPI library version, supported
    # MPI APIs (i.e. MPI-2 C++ bindings). For Fortran we also need to find specific parameters if we're under MPI-3.
    if(MPI_${LANG}_WORKS)
1466 1467
      if("${LANG}" STREQUAL "CXX" AND NOT DEFINED MPI_MPICXX_FOUND)
        if(NOT MPI_CXX_SKIP_MPICXX AND NOT MPI_CXX_VALIDATE_SKIP_MPICXX)
1468 1469
          _MPI_try_staged_settings(${LANG} test_mpi MPICXX FALSE)
          if(MPI_RESULT_${LANG}_test_mpi_MPICXX)
1470
            set(MPI_MPICXX_FOUND TRUE)
1471
          else()
1472
            set(MPI_MPICXX_FOUND FALSE)
1473 1474
          endif()
        else()
1475
          set(MPI_MPICXX_FOUND FALSE)
1476 1477 1478 1479 1480 1481 1482
        endif()
      endif()

      # At this point, we know the bindings present but not the MPI version or anything else.
      if(NOT DEFINED MPI_${LANG}_VERSION)
        unset(MPI_${LANG}_VERSION_MAJOR)
        unset(MPI_${LANG}_VERSION_MINOR)
1483
      endif()
1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550
      set(MPI_BIN_FOLDER ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/FindMPI)

      # For Fortran, we'll want to use the most modern MPI binding to test capabilities other than the
      # Fortran parameters, since those depend on the method of consumption.
      # For C++, we can always use the C bindings, and should do so, since the C++ bindings do not exist in MPI-3
      # whereas the C bindings do, and the C++ bindings never offered any feature advantage over their C counterparts.
      if("${LANG}" STREQUAL "Fortran")
        if(MPI_${LANG}_HAVE_F08_MODULE)
          set(MPI_${LANG}_HIGHEST_METHOD F08_MODULE)
        elseif(MPI_${LANG}_HAVE_F90_MODULE)
          set(MPI_${LANG}_HIGHEST_METHOD F90_MODULE)
        else()
          set(MPI_${LANG}_HIGHEST_METHOD F77_HEADER)
        endif()

        # Another difference between C and Fortran is that we can't use the preprocessor to determine whether MPI_VERSION
        # and MPI_SUBVERSION are provided. These defines did not exist in MPI 1.0 and 1.1 and therefore might not
        # exist. For C/C++, test_mpi.c will handle the MPI_VERSION extraction, but for Fortran, we need mpiver.f90.
        if(NOT DEFINED MPI_${LANG}_VERSION)
          _MPI_try_staged_settings(${LANG} mpiver ${MPI_${LANG}_HIGHEST_METHOD} FALSE)
          if(MPI_RESULT_${LANG}_mpiver_${MPI_${LANG}_HIGHEST_METHOD})
            file(STRINGS ${MPI_BIN_FOLDER}/mpiver_${LANG}.bin _MPI_VERSION_STRING LIMIT_COUNT 1 REGEX "INFO:MPI-VER")
            if("${_MPI_VERSION_STRING}" MATCHES ".*INFO:MPI-VER\\[([0-9]+)\\.([0-9]+)\\].*")
              set(MPI_${LANG}_VERSION_MAJOR "${CMAKE_MATCH_1}")
              set(MPI_${LANG}_VERSION_MINOR "${CMAKE_MATCH_2}")
              set(MPI_${LANG}_VERSION "${MPI_${LANG}_VERSION_MAJOR}.${MPI_${LANG}_VERSION_MINOR}")
            endif()
          endif()
        endif()

        # Finally, we want to find out which capabilities a given interface supports, compare the MPI-3 standard.
        # This is determined by interface specific parameters MPI_SUBARRAYS_SUPPORTED and MPI_ASYNC_PROTECTS_NONBLOCKING
        # and might vary between the different methods of consumption.
        if(MPI_DETERMINE_Fortran_CAPABILITIES AND NOT MPI_Fortran_CAPABILITIES_DETERMINED)
          foreach(mpimethod IN ITEMS F08_MODULE F90_MODULE F77_HEADER)
            if(MPI_${LANG}_HAVE_${mpimethod})
              set(MPI_${LANG}_${mpimethod}_SUBARRAYS FALSE)
              set(MPI_${LANG}_${mpimethod}_ASYNCPROT FALSE)
              _MPI_try_staged_settings(${LANG} fortranparam_mpi ${mpimethod} TRUE)
              if(MPI_RESULT_${LANG}_fortranparam_mpi_${mpimethod} AND
                NOT "${MPI_RUN_RESULT_${LANG}_fortranparam_mpi_${mpimethod}}" STREQUAL "FAILED_TO_RUN")
                if("${MPI_RUN_OUTPUT_${LANG}_fortranparam_mpi_${mpimethod}}" MATCHES
                  ".*INFO:SUBARRAYS\\[ *([TF]) *\\]-ASYNCPROT\\[ *([TF]) *\\].*")
                  if("${CMAKE_MATCH_1}" STREQUAL "T")
                    set(MPI_${LANG}_${mpimethod}_SUBARRAYS TRUE)
                  endif()
                  if("${CMAKE_MATCH_2}" STREQUAL "T")
                    set(MPI_${LANG}_${mpimethod}_ASYNCPROT TRUE)
                  endif()
                endif()
              endif()
            endif()
          endforeach()
          set(MPI_Fortran_CAPABILITIES_DETERMINED TRUE)
        endif()
      else()
        set(MPI_${LANG}_HIGHEST_METHOD normal)

        # By the MPI-2 standard, MPI_VERSION and MPI_SUBVERSION are valid for both C and C++ bindings.
        if(NOT DEFINED MPI_${LANG}_VERSION)
          file(STRINGS ${MPI_BIN_FOLDER}/test_mpi_${LANG}.bin _MPI_VERSION_STRING LIMIT_COUNT 1 REGEX "INFO:MPI-VER")
          if("${_MPI_VERSION_STRING}" MATCHES ".*INFO:MPI-VER\\[([0-9]+)\\.([0-9]+)\\].*")
            set(MPI_${LANG}_VERSION_MAJOR "${CMAKE_MATCH_1}")
            set(MPI_${LANG}_VERSION_MINOR "${CMAKE_MATCH_2}")
            set(MPI_${LANG}_VERSION "${MPI_${LANG}_VERSION_MAJOR}.${MPI_${LANG}_VERSION_MINOR}")
          endif()
        endif()
1551 1552
      endif()

1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570
      unset(MPI_BIN_FOLDER)

      # At this point, we have dealt with determining the MPI version and parameters for each Fortran method available.
      # The one remaining issue is to determine which MPI library is installed.
      # Determining the version and vendor of the MPI library is only possible via MPI_Get_library_version() at runtime,
      # and therefore we cannot do this while cross-compiling (a user may still define MPI_<lang>_LIBRARY_VERSION_STRING
      # themselves and we'll attempt splitting it, which is equivalent to provide the try_run output).
      # It's also worth noting that the installed version string can depend on the language, or on the system the binary
      # runs on if MPI is not statically linked.
      if(MPI_DETERMINE_LIBRARY_VERSION AND NOT MPI_${LANG}_LIBRARY_VERSION_STRING)
        _MPI_try_staged_settings(${LANG} libver_mpi ${MPI_${LANG}_HIGHEST_METHOD} TRUE)
        if(MPI_RESULT_${LANG}_libver_mpi_${MPI_${LANG}_HIGHEST_METHOD} AND
          "${MPI_RUN_RESULT_${LANG}_libver_mpi_${MPI_${LANG}_HIGHEST_METHOD}}" EQUAL "0")
          string(STRIP "${MPI_RUN_OUTPUT_${LANG}_libver_mpi_${MPI_${LANG}_HIGHEST_METHOD}}"
            MPI_${LANG}_LIBRARY_VERSION_STRING)
        else()
          set(MPI_${LANG}_LIBRARY_VERSION_STRING "NOTFOUND")
        endif()
1571
      endif()
1572
    endif()
1573

1574 1575 1576 1577 1578
    set(MPI_${LANG}_FIND_QUIETLY ${MPI_FIND_QUIETLY})
    set(MPI_${LANG}_FIND_VERSION ${MPI_FIND_VERSION})
    set(MPI_${LANG}_FIND_VERSION_EXACT ${MPI_FIND_VERSION_EXACT})

    unset(MPI_${LANG}_REQUIRED_VARS)
1579
    if (NOT "${MPI_${LANG}_COMPILER}" STREQUAL "${CMAKE_${LANG}_COMPILER}")
1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608
      foreach(mpilibname IN LISTS MPI_${LANG}_LIB_NAMES)
        list(APPEND MPI_${LANG}_REQUIRED_VARS "MPI_${mpilibname}_LIBRARY")
      endforeach()
      list(APPEND MPI_${LANG}_REQUIRED_VARS "MPI_${LANG}_LIB_NAMES")
      if("${LANG}" STREQUAL "Fortran")
        # For Fortran we only need one of the module or header directories to have *some* support for MPI.
        if(NOT MPI_${LANG}_MODULE_DIR)
          list(APPEND MPI_${LANG}_REQUIRED_VARS "MPI_${LANG}_F77_HEADER_DIR")
        endif()
        if(NOT MPI_${LANG}_F77_HEADER_DIR)
          list(APPEND MPI_${LANG}_REQUIRED_VARS "MPI_${LANG}_MODULE_DIR")
        endif()
      else()
        list(APPEND MPI_${LANG}_REQUIRED_VARS "MPI_${LANG}_HEADER_DIR")
      endif()
      if(MPI_${LANG}_ADDITIONAL_INCLUDE_VARS)
        foreach(mpiincvar IN LISTS MPI_${LANG}_ADDITIONAL_INCLUDE_VARS)
          list(APPEND MPI_${LANG}_REQUIRED_VARS "MPI_${mpiincvar}_INCLUDE_DIR")
        endforeach()
      endif()
      # Append the works variable now. If the settings did not work, this will show up properly.
      list(APPEND MPI_${LANG}_REQUIRED_VARS "MPI_${LANG}_WORKS")
    else()
      # If the compiler worked implicitly, use its path as output.
      # Should the compiler variable be set, we also require it to work.
      list(APPEND MPI_${LANG}_REQUIRED_VARS "MPI_${LANG}_COMPILER")
      if(MPI_${LANG}_COMPILER)
        list(APPEND MPI_${LANG}_REQUIRED_VARS "MPI_${LANG}_WORKS")
      endif()
1609
    endif()
1610 1611
    find_package_handle_standard_args(MPI_${LANG} REQUIRED_VARS ${MPI_${LANG}_REQUIRED_VARS}
      VERSION_VAR MPI_${LANG}_VERSION)
1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624

    if(DEFINED MPI_${LANG}_VERSION)
      if(NOT _MPI_MIN_VERSION OR _MPI_MIN_VERSION VERSION_GREATER MPI_${LANG}_VERSION)
        set(_MPI_MIN_VERSION MPI_${LANG}_VERSION)
      endif()
    endif()
  endif()
endforeach()

unset(_MPI_REQ_VARS)
foreach(LANG IN ITEMS C CXX Fortran)
  if((NOT MPI_FIND_COMPONENTS AND CMAKE_${LANG}_COMPILER_LOADED) OR LANG IN_LIST MPI_FIND_COMPONENTS)
    list(APPEND _MPI_REQ_VARS "MPI_${LANG}_FOUND")
1625
  endif()
1626
endforeach()
1627

1628 1629 1630 1631 1632 1633 1634 1635 1636
if(MPICXX IN_LIST MPI_FIND_COMPONENTS)
  list(APPEND _MPI_REQ_VARS "MPI_MPICXX_FOUND")
endif()

find_package_handle_standard_args(MPI
    REQUIRED_VARS ${_MPI_REQ_VARS}
    VERSION_VAR ${_MPI_MIN_VERSION}
    HANDLE_COMPONENTS)

1637
#=============================================================================
1638
# More backward compatibility stuff
1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659

# For compatibility reasons, we also define MPIEXEC
set(MPIEXEC "${MPIEXEC_EXECUTABLE}")

# Copy over MPI_<LANG>_INCLUDE_PATH from the assembled INCLUDE_DIRS.
foreach(LANG IN ITEMS C CXX Fortran)
  if(MPI_${LANG}_FOUND)
    set(MPI_${LANG}_INCLUDE_PATH "${MPI_${LANG}_INCLUDE_DIRS}")
    unset(MPI_${LANG}_COMPILE_FLAGS)
    if(MPI_${LANG}_COMPILE_OPTIONS)
      set(MPI_${LANG}_COMPILE_FLAGS "${MPI_${LANG}_COMPILE_OPTIONS}")
    endif()
    if(MPI_${LANG}_COMPILE_DEFINITIONS)
      foreach(_MPI_DEF IN LISTS MPI_${LANG}_COMPILE_DEFINITIONS)
        string(APPEND MPI_${LANG}_COMPILE_FLAGS " -D${_MPI_DEF}")
      endforeach()
    endif()
  endif()
endforeach()

# Bare MPI sans ${LANG} vars are set to CXX then C, depending on what was found.
1660
# This mimics the behavior of the old language-oblivious FindMPI.
1661
set(_MPI_OLD_VARS COMPILER INCLUDE_PATH COMPILE_FLAGS LINK_FLAGS LIBRARIES)
1662 1663 1664 1665 1666 1667 1668 1669 1670
if (MPI_CXX_FOUND)
  foreach (var ${_MPI_OLD_VARS})
    set(MPI_${var} ${MPI_CXX_${var}})
  endforeach()
elseif (MPI_C_FOUND)
  foreach (var ${_MPI_OLD_VARS})
    set(MPI_${var} ${MPI_C_${var}})
  endforeach()
endif()
1671

1672 1673 1674
# Chop MPI_LIBRARIES into the old-style MPI_LIBRARY and MPI_EXTRA_LIBRARY, and set them in cache.
if (MPI_LIBRARIES)
  list(GET MPI_LIBRARIES 0 MPI_LIBRARY_WORK)
1675 1676
  set(MPI_LIBRARY "${MPI_LIBRARY_WORK}")
  unset(MPI_LIBRARY_WORK)
1677
else()
1678
  set(MPI_LIBRARY "MPI_LIBRARY-NOTFOUND")
1679
endif()
1680

1681 1682
list(LENGTH MPI_LIBRARIES MPI_NUMLIBS)
if (MPI_NUMLIBS GREATER 1)
1683
  set(MPI_EXTRA_LIBRARY_WORK "${MPI_LIBRARIES}")
1684
  list(REMOVE_AT MPI_EXTRA_LIBRARY_WORK 0)
1685 1686
  set(MPI_EXTRA_LIBRARY "${MPI_EXTRA_LIBRARY_WORK}")
  unset(MPI_EXTRA_LIBRARY_WORK)
1687
else()
1688
  set(MPI_EXTRA_LIBRARY "MPI_EXTRA_LIBRARY-NOTFOUND")
1689
endif()
1690
set(MPI_IGNORE_LEGACY_VARIABLES TRUE)
1691
#=============================================================================
1692

1693 1694
# unset these vars to cleanup namespace
unset(_MPI_OLD_VARS)
1695
unset(_MPI_PREFIX_PATH)
1696
unset(_MPI_BASE_DIR)
1697
foreach (lang C CXX Fortran)
1698
  unset(_MPI_${LANG}_COMPILER_NAMES)
1699
endforeach()
1700 1701

cmake_policy(POP)