no help entries for non-enableable plugins

library/LuaApi.cpp

@@ -3147,6 +3147,21 @@ static int internal_getCommandHelp(lua_State *L)
     return 1;
 }
 
+static int internal_isPluginEnableable(lua_State *L)
+{
+    auto plugins = Core::getInstance().getPluginManager();
+
+    const char *name = luaL_checkstring(L, 1);
+
+    auto plugin = plugins->getPluginByName(name);
+    if (plugin)
+        lua_pushboolean(L, plugin->can_be_enabled());
+    else
+        lua_pushnil(L);
+
+    return 1;
+}
+
 static int internal_threadid(lua_State *L)
 {
     std::stringstream ss;
@@ -3221,6 +3236,7 @@ static const luaL_Reg dfhack_internal_funcs[] = {
     { "listPlugins", internal_listPlugins },
     { "listCommands", internal_listCommands },
     { "getCommandHelp", internal_getCommandHelp },
+    { "isPluginEnableable", internal_isPluginEnableable },
     { "threadid", internal_threadid },
     { "md5File", internal_md5file },
     { NULL, NULL }

library/lua/helpdb.lua

@@ -305,7 +305,8 @@ local function scan_plugins(old_db, db)
                             HELP_SOURCES.RENDERED or HELP_SOURCES.PLUGIN,
                       command, {entry_types=entry_types})
         end
-        if not includes_plugin then
+        if not includes_plugin and
+                dfhack.internal.isPluginEnableable(plugin) then
             update_db(old_db, db,
                       has_rendered_help(plugin) and
                             HELP_SOURCES.RENDERED or HELP_SOURCES.STUB,