From d95d5f19547a88dc595922f5254c4b308ec643ac Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Thu, 11 Mar 2021 23:52:35 -0500
Subject: [PATCH] store different factory variants in a union

---
 examples/plugins/helloplugin.cpp  | 4 +---
 examples/plugins/morse2plugin.cpp | 6 ++----
 examples/plugins/nve2plugin.cpp   | 4 +---
 src/lammpsplugin.h                | 8 +++++---
 src/plugin.cpp                    | 6 +++---
 5 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/examples/plugins/helloplugin.cpp b/examples/plugins/helloplugin.cpp
index 1c9d0c2779..11f2cfb891 100644
--- a/examples/plugins/helloplugin.cpp
+++ b/examples/plugins/helloplugin.cpp
@@ -41,9 +41,7 @@ extern "C" void lammpsplugin_init(void *lmp, void *handle, void *regfunc)
   plugin.name    = "hello";
   plugin.info    = "Hello world command v1.0";
   plugin.author  = "Axel Kohlmeyer (akohlmey@gmail.com)";
-  plugin.creator1 = nullptr;
-  plugin.creator2 = nullptr;
-  plugin.creator3 = (lammpsplugin_factory3 *) &hellocreator;
+  plugin.creator.v3 = (lammpsplugin_factory3 *) &hellocreator;
   plugin.handle  = handle;
   (*register_plugin)(&plugin,lmp);
 }
diff --git a/examples/plugins/morse2plugin.cpp b/examples/plugins/morse2plugin.cpp
index dfc341e0c0..a4151dcc3d 100644
--- a/examples/plugins/morse2plugin.cpp
+++ b/examples/plugins/morse2plugin.cpp
@@ -31,15 +31,13 @@ extern "C" void lammpsplugin_init(void *lmp, void *handle, void *regfunc)
   plugin.name    = "morse2";
   plugin.info    = "Morse2 variant pair style v1.0";
   plugin.author  = "Axel Kohlmeyer (akohlmey@gmail.com)";
-  plugin.creator1 = (lammpsplugin_factory1 *) &morse2creator;
-  plugin.creator2 = nullptr;
-  plugin.creator3 = nullptr;
+  plugin.creator.v1 = (lammpsplugin_factory1 *) &morse2creator;
   plugin.handle  = handle;
   (*register_plugin)(&plugin,lmp);
 
   // also register morse2/omp pair style. only need to update changed fields
   plugin.name    = "morse2/omp";
   plugin.info    = "Morse2 variant pair style for OpenMP v1.0";
-  plugin.creator1 = (lammpsplugin_factory1 *) &morse2ompcreator;
+  plugin.creator.v1 = (lammpsplugin_factory1 *) &morse2ompcreator;
   (*register_plugin)(&plugin,lmp);
 }
diff --git a/examples/plugins/nve2plugin.cpp b/examples/plugins/nve2plugin.cpp
index 785ec8dbe1..d17db1dfc7 100644
--- a/examples/plugins/nve2plugin.cpp
+++ b/examples/plugins/nve2plugin.cpp
@@ -24,9 +24,7 @@ extern "C" void lammpsplugin_init(void *lmp, void *handle, void *regfunc)
   plugin.name    = "nve2";
   plugin.info    = "NVE2 variant fix style v1.0";
   plugin.author  = "Axel Kohlmeyer (akohlmey@gmail.com)";
-  plugin.creator1 = nullptr;
-  plugin.creator2 = (lammpsplugin_factory2 *) &nve2creator;
-  plugin.creator3 = nullptr;
+  plugin.creator.v2 = (lammpsplugin_factory2 *) &nve2creator;
   plugin.handle  = handle;
   (*register_plugin)(&plugin,lmp);
 }
diff --git a/src/lammpsplugin.h b/src/lammpsplugin.h
index 3de2bcdcdf..1baed9799d 100644
--- a/src/lammpsplugin.h
+++ b/src/lammpsplugin.h
@@ -28,9 +28,11 @@ extern "C" {
     const char *name;
     const char *info;
     const char *author;
-    lammpsplugin_factory1 *creator1;
-    lammpsplugin_factory2 *creator2;
-    lammpsplugin_factory3 *creator3;
+    union {
+      lammpsplugin_factory1 *v1;
+      lammpsplugin_factory2 *v2;
+      lammpsplugin_factory3 *v3;
+    } creator;
     void *handle;
   } lammpsplugin_t;
 
diff --git a/src/plugin.cpp b/src/plugin.cpp
index ea1c46b705..a95fde5b73 100644
--- a/src/plugin.cpp
+++ b/src/plugin.cpp
@@ -129,7 +129,7 @@ namespace LAMMPS_NS
                                                 "style {} from plugin",
                                                 plugin->name));
       }
-      (*pair_map)[plugin->name] = (Force::PairCreator)plugin->creator1;
+      (*pair_map)[plugin->name] = (Force::PairCreator)plugin->creator.v1;
 
     } else if (pstyle == "fix") {
       auto fix_map = lmp->modify->fix_map;
@@ -139,7 +139,7 @@ namespace LAMMPS_NS
                                                 "style {} from plugin",
                                                 plugin->name));
       }
-      (*fix_map)[plugin->name] = (Modify::FixCreator)plugin->creator2;
+      (*fix_map)[plugin->name] = (Modify::FixCreator)plugin->creator.v2;
 
     } else if (pstyle == "command") {
       auto command_map = lmp->input->command_map;
@@ -149,7 +149,7 @@ namespace LAMMPS_NS
                                                 "style {} from plugin",
                                                 plugin->name));
       }
-      (*command_map)[plugin->name] = (Input::CommandCreator)plugin->creator3;
+      (*command_map)[plugin->name] = (Input::CommandCreator)plugin->creator.v3;
 
     } else {
       utils::logmesg(lmp,fmt::format("Loading plugin for {} styles not "