Comment (by Roland Haas):

Well making LD be nvcc gives me extra trouble when compiling ExternalLibraries (same sort of issues that come from having Cactus LIBS mean something different then autoconf’s LIBS).

Instead I peeked at Formaline and wrote a short ExternallLibraries/CUDA thorn that adapts Cactus' link step based on the documentation by NVIDIA. The thorn is here: https://github.com/rhaas80/ExternalLibraries-CUDA.git and the trick is to collect all CUDA code in a new library using nvcc (just as NVIDIA shows):

CACTUSLIBLINKLINE += -l$(CCTK_LIBNAME_PREFIX)CUDA-gpucode

CUDA-LIB = $(CCTK_LIBDIR)/$(LIBNAME_PREFIX)$(CCTK_LIBNAME_PREFIX)CUDA-gpucode$(LIBNAME_SUFFIX)

$(EXEDIR)$(DIRSEP)$(EXE): $(CUDA-LIB)

# TODO: make this depend on only the thorns that REQUIRE CUDA
# TODO: check if depending on LINKLIST would be enough
$(CUDA-LIB): $(CONFIG)/make.thornlist $(CONFIG)/cctki_version.h $(patsubst %,$(CCTK_LIBDIR)/$(LIBNAME_PREFIX)$(CCTK_LIBNAME_PR
--

Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2553/cactus-link-command-uses-cppflags-and