BF: CUDACXXFLAGS was getting mixed into NVCCFLAGS

config/buildSettings.mk

@@ -168,16 +168,30 @@ ifneq (${NVCC}, )
   CUDA_VER      = $(shell ${NVCC} --version | grep -Po "release \K[0-9\.]+")
   GENCODEFLAGS ?= $(shell ${FSLCONFDIR}/supportedGencodes.sh ${CUDA_VER})
 
+  # We use nvcc to compile .cu files, g++ to
+  # compile .cc/.cpp files, and nvcc to perform
+  # the final linking. So we need to manage
+  # compiler/linker flags carefully.
+
+  # CUDACXXFLAGS is to be used when compiling
+  # .cc/.cpp files which are to be linked into
+  # CUDA applications - CUDA-specific include
+  # paths, and any USRNVCCFLAGS are added to it.
+  #
+  # In contrast, NVCCFLAGS is used for compiling
+  # .cu files (and final linking) - it contains
+  # nvcc-specific options.
+  CUDACXXFLAGS ?= -I${CUDA_HOME}/include
+
   # We specify the compiler to use with -ccbin, as
   # nvcc might otherwise naively call "g++", rather
   # than honouring $(CXX). We specifically use
   # "-ccbin" rather than "--compiler-bindir" here,
   # because the conda-forge nvcc wrapper checks for
   # -ccbin, and adds its own if not present.
-  CUDACXXFLAGS ?= -I${CUDA_HOME}/include
-  NVCCFLAGS    ?= ${GENCODEFLAGS} \
-                  -ccbin $(CXX) \
-                  ${CUDACXXFLAGS}
+  NVCCFLAGS    ?= ${GENCODEFLAGS}        \
+                  -ccbin $(CXX)          \
+                  -I${CUDA_HOME}/include
   NVCCLDFLAGS  ?= -L${CUDA_HOME}/lib         \
                   -L${CUDA_HOME}/lib64       \
                   -L${CUDA_HOME}/lib/stubs   \