Improve Python wheel support (#785)

- Use new `NRN_WHEEL_BUILD` option to avoid adding a build flag that is
   not widely supported. This option is added in neuronsimulator/nrn#1661.
- Make `nrnivmodl -coreneuron` fail in GPU builds if a non-NVC++ compiler is used.
- Make `nrnivmodl -coreneuron` fail in GPU builds if a different NVC++ version is used
   to the one used to build the wheel.
- Move some pre-existing logic into a new `cnrn_parse_version` CMake function;
   use it to get `major.minor` version numbers from CUDA and NVHPC versions that
   have `.patch` parts too.
- Modify `CORENEURON_LIB_LINK_FLAGS` to use `-L$(libdir)`, which catches an
   edge case when a patched `libnrniv.so` is being used so the relevant path was not
   already set.
- Make the logic for translating CMake target dependencies into linker flags more verbose.
- Don't print single-MPI paths in dynamic MPI mode.
- Don't add `-I` for MPI headers in dynamic MPI builds.

Author: olupton

CMake/OpenAccHelper.cmake

@@ -4,10 +4,35 @@
 # See top-level LICENSE file for details.
 # =============================================================================
 
+# Helper to parse X.Y[.{anything] into X.Y
+function(cnrn_parse_version FULL_VERSION)
+  cmake_parse_arguments(PARSE_ARGV 1 CNRN_PARSE_VERSION "" "OUTPUT_MAJOR_MINOR" "")
+  if(NOT "${CNRN_PARSE_VERSION_UNPARSED_ARGUMENTS}" STREQUAL "")
+    message(
+      FATAL_ERROR
+        "cnrn_parse_version got unexpected arguments: ${CNRN_PARSE_VERSION_UNPARSED_ARGUMENTS}")
+  endif()
+  string(FIND ${FULL_VERSION} . first_dot)
+  math(EXPR first_dot_plus_one "${first_dot}+1")
+  string(SUBSTRING ${FULL_VERSION} ${first_dot_plus_one} -1 minor_and_later)
+  string(FIND ${minor_and_later} . second_dot_relative)
+  if(${first_dot} EQUAL -1 OR ${second_dot_relative} EQUAL -1)
+    message(FATAL_ERROR "Failed to parse major.minor from ${FULL_VERSION}")
+  endif()
+  math(EXPR second_dot_plus_one "${first_dot}+${second_dot_relative}+1")
+  string(SUBSTRING ${FULL_VERSION} 0 ${second_dot_plus_one} major_minor)
+  set(${CNRN_PARSE_VERSION_OUTPUT_MAJOR_MINOR}
+      ${major_minor}
+      PARENT_SCOPE)
+endfunction()
+
 # =============================================================================
 # Prepare compiler flags for GPU target
 # =============================================================================
 if(CORENRN_ENABLE_GPU)
+  # Get the NVC++ version number for use in nrnivmodl_core_makefile.in
+  cnrn_parse_version(${CMAKE_CXX_COMPILER_VERSION} OUTPUT_MAJOR_MINOR
+                     CORENRN_NVHPC_MAJOR_MINOR_VERSION)
   # Enable cudaProfiler{Start,Stop}() behind the Instrumentor::phase... APIs
   add_compile_definitions(CORENEURON_CUDA_PROFILING CORENEURON_ENABLE_GPU)
   # Plain C++ code in CoreNEURON may need to use CUDA runtime APIs for, for example, starting and
@@ -23,20 +48,7 @@ if(CORENRN_ENABLE_GPU)
     if(NOT ${CMAKE_CUDA_COMPILER_ID} STREQUAL "NVIDIA")
       message(FATAL_ERROR "Unsupported CUDA compiler ${CMAKE_CUDA_COMPILER_ID}")
     endif()
-    # Parse CMAKE_CUDA_COMPILER_VERSION=x.y.z into CUDA_VERSION=x.y
-    string(FIND ${CMAKE_CUDA_COMPILER_VERSION} . first_dot)
-    math(EXPR first_dot_plus_one "${first_dot}+1")
-    string(SUBSTRING ${CMAKE_CUDA_COMPILER_VERSION} ${first_dot_plus_one} -1 minor_and_later)
-    string(FIND ${minor_and_later} . second_dot_relative)
-    if(${first_dot} EQUAL -1 OR ${second_dot_relative} EQUAL -1)
-      message(
-        FATAL_ERROR
-          "Failed to parse a CUDA_VERSION from CMAKE_CUDA_COMPILER_VERSION=${CMAKE_CUDA_COMPILER_VERSION}"
-      )
-    endif()
-    math(EXPR second_dot_plus_one "${first_dot}+${second_dot_relative}+1")
-    string(SUBSTRING ${CMAKE_CUDA_COMPILER_VERSION} 0 ${second_dot_plus_one}
-                     CORENRN_CUDA_VERSION_SHORT)
+    cnrn_parse_version(${CMAKE_CUDA_COMPILER_VERSION} OUTPUT_MAJOR_MINOR CORENRN_CUDA_VERSION_SHORT)
   else()
     # This is a lazy way of getting the major/minor versions separately without parsing
     # ${CMAKE_CUDA_COMPILER_VERSION}
@@ -91,7 +103,7 @@ if(CORENRN_ENABLE_GPU)
     GLOBAL
     PROPERTY
       CORENEURON_LIB_LINK_FLAGS
-      "${NVHPC_ACC_COMP_FLAGS} -rdynamic -lrt -Wl,--whole-archive -L${CMAKE_HOST_SYSTEM_PROCESSOR} -lcorenrnmech -L${CMAKE_INSTALL_PREFIX}/lib -lcoreneuron -Wl,--no-whole-archive"
+      "${NVHPC_ACC_COMP_FLAGS} -rdynamic -lrt -Wl,--whole-archive -L${CMAKE_HOST_SYSTEM_PROCESSOR} -lcorenrnmech -L$(libdir) -lcoreneuron -Wl,--no-whole-archive"
   )
 else()
   set_property(GLOBAL PROPERTY CORENEURON_LIB_LINK_FLAGS

CMakeLists.txt

@@ -426,7 +426,12 @@ endif()
 # =============================================================================
 # Common CXX flags : ignore unknown pragma warnings
 # =============================================================================
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${IGNORE_UNKNOWN_PRAGMA_FLAGS}")
+# Do not set this when building wheels. The nrnivmodl workflow means that we do not know what
+# compiler will be invoked with these flags, so we have to use flags that are as generic as
+# possible.
+if(NOT DEFINED NRN_WHEEL_BUILD OR NOT NRN_WHEEL_BUILD)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${IGNORE_UNKNOWN_PRAGMA_FLAGS}")
+endif()
 
 # =============================================================================
 # Add main directories
@@ -436,7 +441,21 @@ add_subdirectory(coreneuron)
 if(CORENRN_ENABLE_GPU)
   get_target_property(CORENRN_LINK_LIBRARIES coreneuron INTERFACE_LINK_LIBRARIES)
   foreach(LIB ${CORENRN_LINK_LIBRARIES})
-    set_property(GLOBAL APPEND_STRING PROPERTY CORENEURON_LIB_LINK_FLAGS " ${LIB}")
+    get_filename_component(dir_path ${LIB} DIRECTORY)
+    if(TARGET ${LIB})
+      # See, for example, caliper where the coreneuron target depends on the caliper target (so we
+      # get LIB=caliper in this loop), but -l and -L are already added manually here:
+      # https://github.com/BlueBrain/CoreNeuron/blob/856cea4aa647c8f2b0d5bda6d0fc32144c5942e3/CMakeLists.txt#L411-L412
+      message(
+        NOTICE
+        "Ignoring dependency '${LIB}' of 'coreneuron' and assuming relevant flags have already been added to CORENEURON_LIB_LINK_FLAGS."
+      )
+    elseif(NOT dir_path)
+      # In case LIB is not a target but is just the name of a library, e.g. "dl"
+      set_property(GLOBAL APPEND_STRING PROPERTY CORENEURON_LIB_LINK_FLAGS " -l${LIB}")
+    else()
+      set_property(GLOBAL APPEND_STRING PROPERTY CORENEURON_LIB_LINK_FLAGS " ${LIB}")
+    endif()
   endforeach()
 endif()
 
@@ -528,7 +547,6 @@ message(STATUS "COMPILE FLAGS       | ${CORENRN_CXX_FLAGS}")
 message(STATUS "Build Type          | ${COMPILE_LIBRARY_TYPE}")
 message(STATUS "MPI                 | ${CORENRN_ENABLE_MPI}")
 if(CORENRN_ENABLE_MPI)
-  message(STATUS "  INC               | ${MPI_CXX_INCLUDE_PATH}")
   message(STATUS "  DYNAMIC           | ${CORENRN_ENABLE_MPI_DYNAMIC}")
   if(CORENRN_ENABLE_MPI_DYNAMIC AND NRN_MPI_LIBNAME_LIST)
     # ~~~
@@ -543,6 +561,8 @@ if(CORENRN_ENABLE_MPI)
       message(STATUS "    LIBNAME         | core${libname}")
       message(STATUS "    INC             | ${include}")
     endforeach(val)
+  else()
+    message(STATUS "  INC               | ${MPI_CXX_INCLUDE_PATH}")
   endif()
 endif()
 message(STATUS "OpenMP              | ${CORENRN_ENABLE_OPENMP}")

extra/nrnivmodl_core_makefile.in

@@ -52,14 +52,26 @@ CORENRNLIB_FLAGS += $(if @caliper_LIB_DIR@,-L@caliper_LIB_DIR@,)
 # coreneuron/utils/randoms goes first because it needs to override the NEURON
 # directory in INCFLAGS
 INCLUDES = -I$(CORENRN_INC_DIR)/coreneuron/utils/randoms $(INCFLAGS) -I$(CORENRN_INC_DIR)
-INCLUDES += $(if @MPI_CXX_INCLUDE_PATH@, -I$(subst ;, -I,@MPI_CXX_INCLUDE_PATH@),)
+ifeq (@CORENRN_ENABLE_MPI_DYNAMIC@, OFF)
+  INCLUDES += $(if @MPI_CXX_INCLUDE_PATH@, -I$(subst ;, -I,@MPI_CXX_INCLUDE_PATH@),)
+endif
 INCLUDES += $(if @reportinglib_INCLUDE_DIR@, -I$(subst ;, -I,@reportinglib_INCLUDE_DIR@),)
 
 # CXX is always defined. If the definition comes from default change it
 ifeq ($(origin CXX), default)
     CXX = @CMAKE_CXX_COMPILER@
 endif
 
+ifeq (@CORENRN_ENABLE_GPU@, ON)
+  ifneq ($(shell $(CXX) --version | grep -o nvc++), nvc++)
+    $(error GPU wheels are only compatible with the NVIDIA C++ compiler nvc++, but CXX=$(CXX) and --version gives $(shell $(CXX) --version))
+  endif
+  # nvc++ -dumpversion is simpler, but only available from 22.2
+  ifeq ($(findstring nvc++ @CORENRN_NVHPC_MAJOR_MINOR_VERSION@, $(shell $(CXX) --version)),)
+    $(error GPU wheels are currently not compatible across NVIDIA HPC SDK versions. You have $(shell $(CXX) -V | grep nvc++) but this wheel was built with @CORENRN_NVHPC_MAJOR_MINOR_VERSION@.)
+  endif
+endif
+
 # In case of wheel, python and perl exe paths are from the build machine.
 # First prefer env variables set by neuron's nrnivmodl wrapper then check
 # binary used during build. If they don't exist then simply use python and