FIX: TRACE() Message Appears When Closing DAO Objects

SYMPTOMS

The MFC DAO classes provide warning messages to the debug output window when appropriate. This tracing can be turned off by disabling the database tracing by using the Tracer utility. However, two possible problems exist:

• An MFC AppWizard-generated DAO application may display the following TRACE message in the Output Window of the debugger:
  Warning: call Close before destructing Recordset
  This message can safely be ignored. The destructor for the CDaoRecordset class will clean up properly.
• A bug in the debug tracing will incorrectly display the offending module and line of code for _UNICODE builds. There are some TRACE calls in Daocore.cpp in the AfxDaoCheck and AfxDaoTrace functions, which incorrectly use a %s specifier with ANSI strings. This doesn't work in a _UNICODE build, so you are likely to get random characters. These calls should use %hs to force ANSI. As a workaround, rebuild the debug versions of the MFC libraries to use %hs instead of %s. The release versions of the MFC libraries are unaffected by this because TRACE calls are eliminated from release builds.

The information is located in the Readme for Microsoft Visual C++.