log: Construct global logger on first use

src/logging.cpp

@@ -8,6 +8,8 @@
 
 const char * const DEFAULT_DEBUGLOGFILE = "debug.log";
 
+BCLog::Logger& LogInstance()
+{
 /**
  * NOTE: the logger instances is leaked on exit. This is ugly, but will be
  * cleaned up by the OS/libc. Defining a logger as a global object doesn't work
@@ -17,11 +19,15 @@ const char * const DEFAULT_DEBUGLOGFILE = "debug.log";
  * access the logger. When the shutdown sequence is fully audited and tested,
  * explicit destruction of these objects can be implemented by changing this
  * from a raw pointer to a std::unique_ptr.
+ * Since the destructor is never called, the logger and all its members must
+ * have a trivial destructor.
  *
  * This method of initialization was originally introduced in
  * ee3374234c60aba2cc4c5cd5cac1c0aefc2d817c.
  */
-BCLog::Logger* const g_logger = new BCLog::Logger();
+    static BCLog::Logger* g_logger{new BCLog::Logger()};
+    return *g_logger;
+}
 
 bool fLogIPs = DEFAULT_LOGIPS;