PRB: Passing vtMissing as Output Parameter to ADO Function Gives Error (295692)

MORE INFORMATION

Steps to Reproduce Behavior

1. Use the Visual C++ App Wizard to generate a Win32 Console application.
2. Paste the following code in a .cpp file of the application:

   #undef EOF
   #import "c:\program files\common files\system\ado\msado15.dll" no_namespace
   #include <stdio.h>
   #include <conio.h>
   
   void main(void)
   {
   	CoInitialize(NULL);
   
   	_ConnectionPtr conn(__uuidof(Connection));
   	_RecordsetPtr rs(__uuidof(Recordset));
   
   
   	try
   	{
   		// Open connection to pubs database in a SQL Server server.
   		conn->Open( "Provider=SQLOLEDB;Server=Myserver;Database=Pubs;UID=sa;PWD=;", "", "", -1 );
   
   		// First open works fine.
   		rs->PutRefActiveConnection( conn );
   		rs->Open( "select * from authors", vtMissing, adOpenKeyset, adLockOptimistic, adCmdText );
   		rs->Close();
   		rs->PutRefActiveConnection( NULL );
   
   		// Pass vtMissing as an output parameter.
   		conn->Execute( "update authors set au_id=au_id where 1=0", &vtMissing, adCmdText );
   		// To remove the problem, comment the previous line and uncomment the following line.
   		//conn->Execute( "update authors set au_id=au_id where 1=0", NULL, adCmdText );
   
                   // When you open the same recordset again, it fails because ADO has modified vtMissing.
   		rs->PutRefActiveConnection( conn );
   		rs->Open( "select * from authors", vtMissing, adOpenKeyset, adLockOptimistic, adCmdText );
   		rs->Close();
   		rs->PutRefActiveConnection( NULL );
   
   	}
   	catch ( _com_error ex )
   	{
   
   
   		printf( "Com error %s (hr=0x%08x) thrown.\n", (char*) ex.Description(), ex.Error() );
   
   		for ( long i=0; i<conn->Errors->Count; i++ )
   		{
   			printf( "Error[%lu] %s.\n", i, (char*) conn->Errors->Item[i]->Description );
   		}
   	}
   
   	printf( "Test complete. Press any key to exit.\n" );
   	_getch();
   
   }
   					

3. Modify the connection string to your own.
4. Compile and then run the application. Note that the second Open call fails with the error message shown in the "Symptoms" section because vtMissing has been changed by ADO.