Compiling Dolfin with newer PETSc Version failed as version number is not updated by cmake

[Max Winkler]

I encountered some problems when compiling dolfin-1.6.0 with a newer PETSc version and PETSc4py. To reproduce the problem install petsc-3.4.x (e.g. from the repositories of your Linux distribution, mine was Debian 8), and compile dolfin-1.6.0. The CMake script should find all directories automatically.

Then, download a newer version of petsc and petsc4py (I have version 3.7.0) and install them. I compiled the Source code from the official web pages of PETSc and PETSc4py. After updating the CMake-Script using cmake-gui I got the error

-- Checking for package 'PETSc'
-- PETSC_DIR is /usr/local
-- PETSC_ARCH is 
-- Found petscconf.h in /usr/local
-- Performing test PETSC_TEST_RUNS - Success
-- PETSc configured without Cusp support
-- Found PETSc: /usr/local/lib/libpetsc.so (Required is at least version "3.4") 
-- Checking for package 'PETSc4Py'
-- petc4py-version is 3.7.0
CMake Warning at CMakeLists.txt:419 (message):
  PETSc version 3.4.2 and petsc4py version 3.7.0 do not match.  Disabling
  PETSc4py.

The problem is that the petsc version 3.4.2 is read out, although version 3.7.0 is installed. I found out that the variable PETSC_VERSION is cached somewhere and is set to 3.4.2. Removing CMakeCache.txt does not solve the problem as this file is generated by cmake again with the entry PETSC_VERSION=3.4.2.

As a workaround i changed line 250 in the file ${DOLFIN_ROOT}/cmake/modules/FindPETSc.cmake from

set(PETSC_VERSION ${OUTPUT} CACHE TYPE STRING)

to

set(PETSC_VERSION ${OUTPUT})

In both cases the variable OUTPUT contains "3.7.0" but in the first case, the cached value "3.4.2" is taken. Actually there is no reason to reuse a cached variable here as the current PETSc version is read out directly before this.

[Jan Blechta]

PETSc 3.7.0 is not supported by DOLFIN 1.6.0.

[Max Winkler]

You're right. Some interfaces have changed from petsc 3.6 to 3.7, and dolfin won't compile. But the problem I described occurs also when linking dolfin with petsc-3.6.0.

[Jan Blechta]

Ok, but we don't maintain 1.6.0. Plese, try reproducing the problem with dev or latest release. It would be very helpful if you could provide a script for reproducing the problem in a Docker container.

[Prof Garth Wells]

I expect that you have some cache files laying about, or your PETSC_DIR is pointing to the wrong version of PETSC.

If DOLFIN is checking /usr/local before PETSC_DIR, then that is something we would need to fix.