exclude c++ std test for old versions

Co-authored-by: Mikael Öhman <micketeer@gmail.com>

easybuild/easyblocks/n/nvhpc.py

@@ -215,13 +215,14 @@ def sanity_check_step(self):
 
         custom_commands = ["%s -v" % compiler for compiler in compiler_names]
 
-        # compile minimal example using -std=c++20 to catch issue where it picks up the wrong GCC
-        # (as long as system gcc is < 9.0)
-        # see: https://github.com/easybuilders/easybuild-easyblocks/pull/3240
-        tmpdir = tempfile.mkdtemp()
-        write_file(os.path.join(tmpdir, 'minimal.cpp'), NVHPC_MINIMAL_EXAMPLE)
-        minimal_compiler_cmd = "cd %s && nvc++ -std=c++20 minimal.cpp -o minimal" % tmpdir
-        custom_commands.append(minimal_compiler_cmd)
+        if LooseVersion(self.version) >= LooseVersion('21'):
+            # compile minimal example using -std=c++20 to catch issue where it picks up the wrong GCC
+            # (as long as system gcc is < 9.0)
+            # see: https://github.com/easybuilders/easybuild-easyblocks/pull/3240
+            tmpdir = tempfile.mkdtemp()
+            write_file(os.path.join(tmpdir, 'minimal.cpp'), NVHPC_MINIMAL_EXAMPLE)
+            minimal_compiler_cmd = "cd %s && nvc++ -std=c++20 minimal.cpp -o minimal" % tmpdir
+            custom_commands.append(minimal_compiler_cmd)
 
         super(EB_NVHPC, self).sanity_check_step(custom_paths=custom_paths, custom_commands=custom_commands)