check for compatible LAMMPS version when creating LAMMPS instance

This check must be done at runtime, since the LAMMPS shared library
may have been loaded dynamically and thus required library functions
may not be present or missing features with too only a LAMMPS version.

tools/lammps-gui/lammpsgui.cpp

@@ -1398,6 +1398,15 @@ void LammpsGui::start_lammps()
     lammps.open(narg, args);
     lammpsstatus->show();
 
+    // must have at least 2 August 2023 version of LAMMPS
+    // TODO: must update this check before next feature release
+    if (lammps.version() < 20230802) {
+        QMessageBox::critical(this, "Incompatible LAMMPS Version",
+                              "LAMMPS-GUI version " LAMMPS_GUI_VERSION " requires\n"
+                              "LAMMPS version 2 August 2023 or later");
+        exit(1);
+    }
+
     // delete additional arguments again (3 were there initially
     while ((int)lammps_args.size() > initial_narg) {
         delete lammps_args.back();

tools/lammps-gui/lammpswrapper.cpp

@@ -36,6 +36,19 @@ void LammpsWrapper::open(int narg, char **args)
 #endif
 }
 
+int LammpsWrapper::version()
+{
+    int val = 0;
+    if (lammps_handle) {
+#if defined(LAMMPS_GUI_USE_PLUGIN)
+        val = ((liblammpsplugin_t *)plugin_handle)->version(lammps_handle);
+#else
+        val = lammps_version(lammps_handle);
+#endif
+    }
+    return val;
+}
+
 int LammpsWrapper::extract_setting(const char *keyword)
 {
     int val = 0;

tools/lammps-gui/lammpswrapper.h

@@ -29,6 +29,7 @@ public:
 
     void force_timeout();
 
+    int version();
     int extract_setting(const char *keyword);
     void *extract_global(const char *keyword);
     void *extract_atom(const char *keyword);