On Fri, Mar 14, 2008 at 07:04:40PM +0100, Ilmar Wilbers wrote:
> I spent hours today debugging a problem I kept getting when compiling
> dolfin with petsc (and openmpi) on my Macbook (really, the demos):
> /usr/local/include/petscmath.h:16: error: 'MPI_Datatype' does not name a
> type
> /usr/local/include/petscmath.h:17: error: 'MPI_Datatype' does not name a
> type
> /usr/local/include/petscmath.h:294: error: 'MPI_Comm' has not been declared
> /usr/local/include/petscmath.h:295: error: 'MPI_Comm' has not been declared
> /usr/local/include/petscmath.h:296: error: 'MPI_Comm' has not been declared
> /usr/local/include/petsc.h:451: error: 'MPI_Comm' does not name a type
> /usr/local/include/petsc.h:469: error: expected primary-expression
> before '(' token
> [...]
> /usr/local/include/petscksp.h:528: error: initializer expression list
> treated as compound expression
> scons: *** [demo/fem/assembly/cpp/main.o] Error 1
> scons: building terminated because of errors.
>
> I dug deep down in petsc internals, its includes, dependencies etc. At
> last I found the error, but it had nothing to do with petsc or MPI.
> Someone had checked in the file MPI.h in dolfin/main. OSX is, just as
> Windows, case-insensitive (except Åsmunds machine, as he made it
> case-sensitive). Because petsc.h includes mpi.h, and the flag
> -I/dolfin/main is present as well as -I/usr/include, petsc tried to
> include the file dolfin/main/MPI.h, which certainly does not have all
> the declarations as /usr/include/mpi.h
>
> This problem will affect all Mac and Window users. I don't know where
> the file MPI.h is included, but simply renaming it worked for me. Can
> the right person (Garth, I saw your name in the file?) rename the file
> and all places it is used?
>
> I guess the conclusion is that we should avoid all file names that,
> regardless of case, might be used elsewhere.
I'm not so sure. It would be very difficult if we had to look at all
other systems when choosing our file names. We have several files that
are likely to appear elsewhere: init,h, constants.h, basic.h, File.h
etc. The important thing should be that we define everything under
our own namespace dolfin:: and install everything under $prefix/dolfin.
Why does the build system pick up MPI.h from DOLFIN? MPI.h should only
be available as <dolfin/main/MPI.h> and this is unlikely to appear in
PETSc.
