use g++-7

debian/control

@@ -8,6 +8,7 @@ Vcs-Browser: https://anonscm.debian.org/cgit/debian-science/packages/dune-common
 Vcs-Git: https://anonscm.debian.org/git/debian-science/packages/dune-common.git
 Homepage: http://www.dune-project.org/
 Build-Depends: debhelper (>= 9),
+ g++-7,
  cmake, gfortran, mpi-default-bin, mpi-default-dev, pkg-config, python3
 Build-Depends-Indep: doxygen, ghostscript, graphviz, imagemagick, texlive-latex-extra, texlive-latex-recommended, texlive-pictures, python3-sphinx
 
@@ -16,6 +17,7 @@ Section: libdevel
 Architecture: any
 Multi-Arch: same
 Depends: ${misc:Depends}, ${shlibs:Depends},
+ g++-7,
  pkg-config, python, python-pyparsing
 Breaks: libdune-functions-dev (<< 2.5.0~)
 Replaces: libdune-functions-dev (<< 2.5.0~)

debian/dune-debian.mk

@@ -2,7 +2,7 @@ include /usr/share/dpkg/pkg-info.mk
 
 DUNE_CTEST ?= /usr/bin/dune-ctest
 
-DUNE_DEBIAN_CMAKE_FLAGS = -DBUILD_SHARED_LIBS=1
+DUNE_DEBIAN_CMAKE_FLAGS = -DBUILD_SHARED_LIBS=1 -DCMAKE_CXX_COMPILER=/usr/bin/g++-7
 
 DUNE_DEBIAN_SHLIB = $(subst ~,.,lib$(DEB_SOURCE)-$(DEB_VERSION_UPSTREAM))