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Diffstat (limited to 'lib/spack/docs/packaging_guide.rst')
| -rw-r--r-- | lib/spack/docs/packaging_guide.rst | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/lib/spack/docs/packaging_guide.rst b/lib/spack/docs/packaging_guide.rst index 519c0da232..31c676d4f5 100644 --- a/lib/spack/docs/packaging_guide.rst +++ b/lib/spack/docs/packaging_guide.rst @@ -1831,6 +1831,42 @@ successfully find ``libdwarf.h`` and ``libdwarf.so``, without the packager having to provide ``--with-libdwarf=/path/to/libdwarf`` on the command line. +Compiler flags +~~~~~~~~~~~~~~ +In rare circumstances such as compiling and running small unit tests, a package +developer may need to know what are the appropriate compiler flags to enable +features like ``OpenMP``, ``c++11``, ``c++14`` and alike. To that end the +compiler classes in ``spack`` implement the following _properties_ : +``openmp_flag``, ``cxx11_flag``, ``cxx14_flag``, which can be accessed in a +package by ``self.compiler.cxx11_flag`` and alike. Note that the implementation +is such that if a given compiler version does not support this feature, an +error will be produced. Therefore package developers can also use these properties +to assert that a compiler supports the requested feature. This is handy when a +package supports additional variants like + +.. code-block:: python + + variant('openmp', default=True, description="Enable OpenMP support.") + + + +Message Parsing Interface (MPI) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +It is common for high performance computing software/packages to use ``MPI``. +As a result of conretization, a given package can be built using different +implementations of MPI such as ``Openmpi``, ``MPICH`` or ``IntelMPI``. +In some scenarios to configure a package one have to provide it with appropriate MPI +compiler wrappers such as ``mpicc``, ``mpic++``. +However different implementations of ``MPI`` may have different names for those +wrappers. In order to make package's ``install()`` method indifferent to the +choice ``MPI`` implementation, each package which implements ``MPI`` sets up +``self.spec.mpicc``, ``self.spec.mpicxx``, ``self.spec.mpifc`` and ``self.spec.mpif77`` +to point to ``C``, ``C++``, ``Fortran 90`` and ``Fortran 77`` ``MPI`` wrappers. +Package developers are advised to use these variables, for example ``self.spec['mpi'].mpicc`` +instead of hard-coding ``join_path(self.spec['mpi'].prefix.bin, 'mpicc')`` for +the reasons outlined above. + + Forking ``install()`` ~~~~~~~~~~~~~~~~~~~~~ |