[petsc-dev] Sean is going to love this

[Barry Smith]

> On Dec 23, 2014, at 6:11 PM, Sean Farley <sean.michael.farley at gmail.com> wrote:
> 
> 
> Barry Smith writes:
> 
>>   Sean,
>> 
>>    Say I am writing a PETSc package (for any generic packaging system) that will use the MPICH compilers package and the BLAS/LAPACK package (and say, the hdf5 package). How do I indicate to PETSc's configure the information for MPICH, BLAS/LAPACK, and hdf5 so they will be correct for users when they link and run their applications? That is, I don't want to randomly list some hdf5 on the system but is it enough to just list the exact location of the hdf5 I know the package manager will install hdf5 to?
> 
> That is a hard problem. Jed and others will chime in on this problem,
> but this is why some packages have a binary / script that outputs its
> compiler / linker flags. For example, netcdf has nc-config:
> 
> $ nc-config --has-hdf5
> yes
> 
> $ nc-config --libs
> -L/opt/local/lib -lnetcdf
> 
> There is also pkg-config:
> 
> $ pkg-config --libs libpng
> -L/opt/local/lib -lpng16
> 
> Ideally, package managers should provide this information. Currently,
> they do not. For PETSc, this would mean something akin to 'petscmpiexec'
> and / or supplying this information to pkg-config (this actually should
> be fairly easy).
> 
> An end-user would then use pkg-config or a PETSc-provided script for
> compiling and linking,
> 
> $ pkg-config --libs petsc
> -L/opt/local/lib -lnetcdf -lpetsc -L/opt/local/lib/mpich-mp -lmpi -lpmpi

  Yeah in theory we do this.

  But this actually doesn't answer my question; I'm also asking about the situation when the package system (like brew) is compiling the package on the users machine.  Say I need the -I info for hdf5 to pass to PETSc's configure. If the user has selected a nonstandard location for installs with brew(not /usr/local) how do I know what directory to pass with the -I ? Somehow the package system has to provide the information for me to use in calling configure.

  Barry