Merge pull request #2840 from Steven-Roberts/sundials-warning

Add warnings about SUNDIALS versions <4

cmake/FindSUNDIALS.cmake

@@ -121,6 +121,10 @@ if (SUNDIALS_INCLUDE_DIR)
   set(SUNDIALS_VERSION "${SUNDIALS_VERSION_MAJOR}.${SUNDIALS_VERSION_MINOR}.${SUNDIALS_VERSION_PATCH}" CACHE STRING "SUNDIALS version")
 endif()
 
+if("${SUNDIALS_VERSION_MAJOR}" LESS 4)
+  message(WARNING "SUNDIALS versions <4 are depricated and will not be supported in the next release")
+endif()
+
 if (SUNDIALS_DEBUG)
   message(STATUS "[ ${CMAKE_CURRENT_LIST_FILE}:${CMAKE_CURRENT_LIST_LINE} ] "
     " SUNDIALS_VERSION = ${SUNDIALS_VERSION}")

manual/sphinx/user_docs/advanced_install.rst

@@ -430,9 +430,10 @@ solver. Currently, BOUT++ also supports the SUNDIALS solvers CVODE, IDA
 and ARKODE which are available from
 https://computation.llnl.gov/casc/sundials/main.html.
 
-.. note:: BOUT++ currently supports SUNDIALS > 2.6, up to 5.4.0 as of
-          September 2020. It is advisable to use the highest possible
-          version
+.. note:: BOUT++ currently supports SUNDIALS > 2.6, up to 6.7.0 as of
+          January 2024. It is advisable to use the highest possible
+          version. Support for SUNDIALS versions < 4 will be removed
+          in the next release.
 
 The full installation guide is found in the downloaded ``.tar.gz``,
 but we will provide a step-by-step guide to install it and make it