From a232565b3ea2cde7212916ac70b4d94b1399be73 Mon Sep 17 00:00:00 2001
From: Edward d'Auvergne <edward@nmr-relax.com>
Date: Fri, 4 May 2018 09:09:15 +0200
Subject: [PATCH] SGSubsystemMgr: Bug fix for the global_registrations vector.

The vector is now a static function variable that is returned by reference by
the new getGlobalRegistrations() function, which remains in the anonymous
namespace.

This solves the issue of the global_registrations vector being populated during
static init, but then been subsequently allocated and hence reset at the end of
static init.
---
 simgear/structure/subsystem_mgr.cxx | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/simgear/structure/subsystem_mgr.cxx b/simgear/structure/subsystem_mgr.cxx
index c5ae8cad..80c7ef0a 100644
--- a/simgear/structure/subsystem_mgr.cxx
+++ b/simgear/structure/subsystem_mgr.cxx
@@ -913,10 +913,15 @@ namespace  {
     
     using SybsystemRegistrationVec = std::vector<RegisteredSubsystemData>;
     
-    SybsystemRegistrationVec global_registrations;
-    
+    SybsystemRegistrationVec &getGlobalRegistrations()
+    {
+        static SybsystemRegistrationVec global_registrations;
+        return global_registrations;
+    }
+
     SybsystemRegistrationVec::const_iterator findRegistration(const std::string& name)
     {
+        auto &global_registrations = getGlobalRegistrations();
         auto it = std::find_if(global_registrations.begin(),
                                global_registrations.end(),
                                [name](const RegisteredSubsystemData& d)
@@ -932,6 +937,7 @@ void SGSubsystemMgr::registerSubsystem(const std::string& name,
                                        double updateInterval,
                                        std::initializer_list<Dependency> deps)
 {
+    auto &global_registrations = getGlobalRegistrations();
     if (findRegistration(name) != global_registrations.end()) {
         throw sg_exception("duplicate subsystem registration for: " + name);
     }
@@ -945,6 +951,7 @@ void SGSubsystemMgr::registerSubsystem(const std::string& name,
 auto SGSubsystemMgr::defaultGroupFor(const char* name) -> GroupType
 {
     auto it = findRegistration(name);
+    auto &global_registrations = getGlobalRegistrations();
     if (it == global_registrations.end()) {
         throw sg_exception("unknown subsystem registration for: " + std::string(name));
     }
@@ -955,6 +962,7 @@ auto SGSubsystemMgr::defaultGroupFor(const char* name) -> GroupType
 double SGSubsystemMgr::defaultUpdateIntervalFor(const char* name)
 {
     auto it = findRegistration(name);
+    auto &global_registrations = getGlobalRegistrations();
     if (it == global_registrations.end()) {
         throw sg_exception("unknown subsystem registration for: " + std::string(name));
     }
@@ -966,6 +974,7 @@ const SGSubsystemMgr::DependencyVec&
 SGSubsystemMgr::dependsFor(const char* name)
 {
     auto it = findRegistration(name);
+    auto &global_registrations = getGlobalRegistrations();
     if (it == global_registrations.end()) {
         throw sg_exception("unknown subsystem registration for: " + std::string(name));
     }
@@ -977,6 +986,7 @@ SGSubsystemRef
 SGSubsystemMgr::create(const std::string& name)
 {
     auto it = findRegistration(name);
+    auto &global_registrations = getGlobalRegistrations();
     if (it == global_registrations.end()) {
         return {}; // or should this throw with a 'not registered'?
     }
@@ -998,6 +1008,7 @@ SGSubsystemRef
 SGSubsystemMgr::createInstance(const std::string& name, const std::string& instanceName)
 {
     auto it = findRegistration(name);
+    auto &global_registrations = getGlobalRegistrations();
     if (it == global_registrations.end()) {
         return {}; // or should this throw with a 'not registered'?
     }