From 0fb210edbfe388ff7f49bf26fca393e6aa549029 Mon Sep 17 00:00:00 2001
From: mpv <mpv@opencascade.com>
Date: Thu, 30 Jul 2020 19:30:21 +0300
Subject: [PATCH] 0031681: Foundation Classes - Shared Libraries Cannot Be
 Loaded

Standard_ErrorHandler now accesses global mutex via proxy function
instead of a global variable to avoid initialization order issues.
---
 src/Standard/Standard_ErrorHandler.cxx | 30 +++++++++++++++-----------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/src/Standard/Standard_ErrorHandler.cxx b/src/Standard/Standard_ErrorHandler.cxx
index 49ac0def03..7129919c4a 100644
--- a/src/Standard/Standard_ErrorHandler.cxx
+++ b/src/Standard/Standard_ErrorHandler.cxx
@@ -39,10 +39,16 @@
 //==== The top of the Errors Stack ===========================================
 static Standard_ErrorHandler* Top = 0;
 
-// A mutex to protect from concurrent access to Top
-// Note that we should NOT use Sentry while in this class, as Sentry
-// would register mutex as callback in the current exception handler
-static Standard_Mutex theMutex; 
+//! A mutex to protect from concurrent access to Top.
+//! Mutex is defined as function to avoid issues caused by
+//! an undefined static variables initialization order across compilation units (@sa #0031681 bug).
+//! Note that we should NOT use Sentry while in this class, as Sentry
+//! would register mutex as callback in the current exception handler.
+static Standard_Mutex& GetMutex()
+{
+  static Standard_Mutex theMutex;
+  return theMutex;
+}
 
 static inline Standard_ThreadId GetThreadID()
 {
@@ -64,10 +70,10 @@ Standard_ErrorHandler::Standard_ErrorHandler () :
   myThread   = GetThreadID();
   memset (&myLabel, 0, sizeof(myLabel));
 
-  theMutex.Lock();
+  GetMutex().Lock();
   myPrevious = Top;
   Top        = this;
-  theMutex.Unlock();
+  GetMutex().Unlock();
 }
 
 
@@ -94,7 +100,7 @@ void Standard_ErrorHandler::Destroy()
 void Standard_ErrorHandler::Unlink()
 {
   // put a lock on the stack
-  theMutex.Lock();
+  GetMutex().Lock();
   
   Standard_ErrorHandler* aPrevious = 0;
   Standard_ErrorHandler* aCurrent = Top;
@@ -106,7 +112,7 @@ void Standard_ErrorHandler::Unlink()
   }
   
   if(aCurrent==0) {
-    theMutex.Unlock();
+    GetMutex().Unlock();
     return;
   }
   
@@ -118,7 +124,7 @@ void Standard_ErrorHandler::Unlink()
     aPrevious->myPrevious=aCurrent->myPrevious;
   }
   myPrevious = 0;
-  theMutex.Unlock();
+  GetMutex().Unlock();
 
   // unlink and destroy all registered callbacks
   Standard_Address aPtr = aCurrent->myCallbackPtr;
@@ -217,7 +223,7 @@ Standard_ErrorHandler* Standard_ErrorHandler::FindHandler(const Standard_Handler
                                                           const Standard_Boolean theUnlink)
 {
   // lock the stack
-  theMutex.Lock();
+  GetMutex().Lock();
     
   // Find the current ErrorHandler Accordin tread
   Standard_ErrorHandler* aPrevious = 0;
@@ -262,7 +268,7 @@ Standard_ErrorHandler* Standard_ErrorHandler::FindHandler(const Standard_Handler
       aStop = Standard_True;
     }
   }
-  theMutex.Unlock();
+  GetMutex().Unlock();
   
   return anActive;
 }
@@ -307,4 +313,4 @@ void Standard_ErrorHandler::Callback::UnregisterCallback ()
     ((Standard_ErrorHandler*)myHandler)->myCallbackPtr = (Standard_ErrorHandler::Callback*)myNext;
   myHandler = myNext = myPrev = 0;
 }
-#endif
\ No newline at end of file
+#endif
-- 
2.20.1