fix cmake expand_instantiations ldgold workaround

Avoid cmake error if DEAL_II_LINKER_FLAGS is empty.

diff --git a/cmake/scripts/CMakeLists.txt b/cmake/scripts/CMakeLists.txt
index a51f8cb04c42285befeaca487d16533cd84f3e9a..5db06b730f19297abdc5e129c592b5dc8527419d 100644 (file)
--- a/cmake/scripts/CMakeLists.txt
+++ b/cmake/scripts/CMakeLists.txt
@@ -27,7 +27,8 @@ ADD_EXECUTABLE(expand_instantiations_exe expand_instantiations.cc)
 # linker flag, filtering this one command out of the list of flags
 # does not harm either.
 #
-STRING(REPLACE "-fuse-ld=gold" "" _expand_instantiations_link_flags ${DEAL_II_LINKER_FLAGS} )
+STRING(REPLACE "-fuse-ld=gold" "" _expand_instantiations_link_flags "${DEAL_II_LINKER_FLAGS}" )
+
 SET_TARGET_PROPERTIES(expand_instantiations_exe PROPERTIES
   LINK_FLAGS "${_expand_instantiations_link_flags}"
   LINKER_LANGUAGE "CXX"