ChangeLogTag: Thu Apr 15 14:27:12 2004 Jeff Parsons <j.parsons@vanderbilt.edu>

3 files changed, 55 insertions, 0 deletions

diff --git a/TAO/ChangeLog b/TAO/ChangeLog
index 71a0200a700..cff307ff261 100644
--- a/TAO/ChangeLog
+++ b/TAO/ChangeLog
@@ -1,3 +1,41 @@
+Thu Apr 15 14:27:12 2004  Jeff Parsons <j.parsons@vanderbilt.edu>
+
+        * tao/OctetSeqC.h:
+        
+          Reluctantly added a handcraft to this generated file, but it
+          wouldn't work anywhere else. Visual Studio .NET has a bug
+          (see http://support.microsoft.com/default.aspx?scid=kb;en-us;309801)
+          where a template base class is not imported correctly, leading
+          to 'multiply defined' link errors if an application has a
+          child of the same base class. The TAO POA library uses a
+          sequence of CORBA::OctetSeq, resulting in the above link error
+          if an application server uses the same type. Since the conflict
+          is with *C.obj, the fix must go into a file that will be included
+          in that translation unit, to force the correct import. We force
+          the import with 
+          
+          #if defined ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION_EXPORT
+            template class TAO_Export TAO_Unbounded_Sequence<CORBA::OctetSeq>;
+          #endif /* ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION_EXPORT */
+          
+          and the TAO export macro will be read by the application as
+          __declspec(dllimport). Placement of the instantiation was tricky,
+          since it had to be a place where
+          
+          - TAO_Unbounded_Sequence is known
+          - CORBA::OctetSeq is known
+          - the instantiation will be seen when building *C.obj
+          - it will not conflict with the implicit PortableServer export
+          
+          Thanks to Bala <bala@dre.vanderbilt.edu> for his help with this
+          bug, and to Scott Gammill <zumo@flashmail.com> for both reporting
+          the bug and for pointing us to the Microsoft Knowledge Base article
+          that finally explained it.
+          
+        * tests/IDL_Test/sequence.idl:
+        
+          Added IDL to test for the above bug.
+
 Thu Apr 15 12:02:20 2004  Ossama Othman  <ossama@dre.vanderbilt.edu>
 
 	* orbsvcs/orbsvcs/SSLIOP/SSLIOP_Acceptor.cpp:
diff --git a/TAO/tao/OctetSeqC.h b/TAO/tao/OctetSeqC.h
index e6d48fbdad0..c928d7a1207 100644
--- a/TAO/tao/OctetSeqC.h
+++ b/TAO/tao/OctetSeqC.h
@@ -147,6 +147,18 @@ namespace TAO
 {
 }
 
+// Workaround for a Visual Studio .NET bug where this class is not
+// properly imported by an application if typedef'd or subclassed,
+// resulting in 'multiply defined' link errors. The export macro
+// here forces an explicit import by the application. Please see
+// http://support.microsoft.com/default.aspx?scid=kb;en-us;309801
+// The problem stems from use of the type below in PortableServer,
+// but we put the instantiation here because the application will
+// need to see it in *C.h to avoid the error.
+#if defined ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION_EXPORT
+  template class TAO_Export TAO_Unbounded_Sequence<CORBA::OctetSeq>;
+#endif /* ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION_EXPORT */
+
 // TAO_IDL - Generated from
 // be\be_visitor_sequence/any_op_ch.cpp:52
 
diff --git a/TAO/tests/IDL_Test/sequence.idl b/TAO/tests/IDL_Test/sequence.idl
index 759b4899763..9cbd802c9b4 100644
--- a/TAO/tests/IDL_Test/sequence.idl
+++ b/TAO/tests/IDL_Test/sequence.idl
@@ -19,6 +19,11 @@
 //
 // ============================================================================
 
+#include "tao/OctetSeq.pidl"
+
+// This will produce a link error if a handcraft we have added to
+// tao/OctetSeqC.h is ever removed.
+typedef sequence<CORBA::OctetSeq> OctetSeqSeq;
 
 // Bounded string elements of a sequence,
 // require the use of CORBA_Any::to_char.