FIX: TRACE() Message Appears When Closing DAO Objects

• The Microsoft Foundation Classes (MFC), included with:
  • Microsoft Visual C++ 32-bit Edition, versions 4.0, 4.1

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.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual C++ version 4.2.

Additional query words: kbVC400bug

Keywords : kbDAO kbDatabase kbMFC kbVC kbVC420fix
Version : winnt:
Platform : winnt
Issue type : kbbug