FIX: What's New: Bug Fixes Made in Visual C++ Version 2.1

• An assertion failure occurs when using RFX_Text with a column of type SQL_VARCHAR that is wider than 255 bytes. Some drivers implement columns of type SQL_VARCHAR that allow more than 255 bytes, so in those cases, the MFC assertion would not be valid. For more information, please see the following article in the Microsoft Knowledge Base:

  120888 FIX: Assertion Fails When Use RFX_Text() w/ SQL_VARCHAR Column

• Calling MovePrev after you move past the end of a recordset or calling MoveNext after you move past the beginning of a recordset results in no action. You needed two MoveNext calls or two MovePrev calls to get to the first or last record of the recordset, respectively. Note that if your existing code calls either of these functions twice in a row to work around this problem, the code will now move an extra record.
• MFC had a problem with the way the Open Database Connectivity (ODBC) driver for Microsoft Access version 2.0 represented its Yes/No (bit) fields. The Microsoft Access driver mapped its Yes/No fields to the SQL_BINARY data type rather than SQL_BIT. This meant that MFC database programmers could not use BOOL for these fields in recordsets. This behavior was incompatible with the previous Microsoft Access driver version. Updated ODBC drivers now eliminate this problem.
• In an application that does not use a CRecordView-derived class, MFC database code fails to update Null fields correctly. On a CRecordset::Edit call in an application not using a CRecordView, Edit failed to correctly update the status of fields marked Null to not Null and vice versa; it was necessary to explicitly set the status by calling the CRecordset member function SetFieldNull with the appropriate parameter. For more information, please see the following article in the Microsoft Knowledge Base:

  123652 FIX: Update() Fails to Write Changed Text Field

• OLE servers lost their toolbars when the container window was resized. If you resized the container's frame window to reduce its height, the server's toolbar disappeared and was replaced by the container's toolbar. As the frame window was made larger, the container's toolbar disappeared, but the server's toolbar did not reappear.
• The pvarResult from COleDispatchDriver::InvokeHelper should be NULL when vtRet is VT_EMPTY. But a call to COleDispatchDriver::InvokeHelper caused the server to generate an error when the return type was VT_EMPTY. The nature of the error depended on the automation server. For example, the Microsoft WordBasic automation server caused the following error on some methods with a return type of void (_DEBUG build): "Assertion Failed Line 315, OLEDISP2.CPP." Using the debugger to examine the excepInfo structure showed that the btrDescription member contained this message: "Non Function called as function." For more information, please see the following article in the Microsoft Knowledge Base:

  121218 FIX: pvarResult Should Be NULL When vtRet==VT_EMPTY

• The CMainView::DoPasteNative member function in the OCLIENT sample application failed to handle an error, which caused a failure. The

     function returned without throwing an exception when the pFile variable

  was NULL. This has been corrected to throw a CFileException.
• A default OLE container application with OLE Automation enabled initialized the m_pSelection data member in the wrong function. AppWizard initialized the member to NULL in the view's nInitialUpdate member function rather than in the view constructor. This led to an assertion failure in COleClientItem::OnDraw when you attempted to create a container document with another application, as for example using Visual Basic's CreateObject function. The member is now correctly initialized in both places. (This bug applies to both 16- and 32-bit versions.)
• The ANSI mapping layer in MFCANS32.DLL handled standard OLE aggregation incorrectly. The DLL incorrectly called AddRef where it should not have under aggregation rules. There was also a problem with how MFC wrapped the "inner IUnknown." For more information, see Technical Note 49 under MFC in Books Online.
• COleDataSource::OnRenderData returned NOERROR instead of TRUE. Because the function return type is prototyped as BOOL, NOERROR is interpreted as FALSE. (This bug applies to both 16- and 32-bit versions.)
• The EXCEPINFO structure is not correctly initialized for an OLE control. Information already available about an exception -- in particular, the control name and the name of the control's help file -- was overwritten. This has been corrected so that the EXCEPINFO structure is only filled if it is empty. (This bug applies to both 16- and 32-bit versions.)
• When Microsoft Excel deactivated an in-place object whose frame window has a splitter that contained two or more views, the MFC application caused a general protection fault. The COleServerDoc::OnShowDocument function destroyed the frame window in this case, leading to the general protection fault. This applied only to SDI-based in-place servers.
• The wrong window was determined to be the active window when the HIERSVR sample application was embedded in Microsoft Excel. When you used Edit Insert in Excel to insert a HIERSVR object, selected the object, then chose any command that opened a dialog box, the dialog box had the wrong parent. The parent was in Excel, not HIERSVR. The m_pActiveWnd data member needed to be set back to NULL once an object left the UI-active state. This was true for both 16- and 32-bit Excel. (This bug applies to both 16- and 32-bit versions of Visual C++.)
• Removing FWS_ADDTOTITLE caused an incorrect SaveModified call. Removing the FWS_ADDTOTITLE style from a CMDIChildWnd-derived class caused SaveModified to be called when each view attached to the document was closed. This caused a problem in closing the frame window. For more information, please see the following article in the Microsoft Knowledge Base:

  99182 How to Change an MFC-Based MDI Child Window's Frame Text

• The CMDIFrameWnd caption was not updated when a maximized child window closed. Under certain circumstances, closing a maximized child window did not properly update the caption of the main frame window in a multiple document interface (MDI) application. This caused the main frame window caption to show a document name even with no documents open. The bug appeared when the child window was maximized and the main frame window was narrower than its menu bar, so the menu wrapped to the next line.
• The command update handler for a menu item was not called if you added or removed the previous menu item during a command handler call. If you added or removed a menu item during a command handler call, the update handler was not called for the menu item immediately following the added or removed item. For example, menu items below the most-recently-used (MRU) list on the File menu could be affected by this problem.
• Problems occurred when you used width specifiers in CString::Format. In the CString::Format member function, using a negative width specifier in a %s metacharacter that was larger than the actual length of the string being substituted led to an assertion failure in file: STREX.CPP, Line 360. You might have a metacharacter like this if you wanted the string to be left-justified within the number of columns you specified as the width.
• CString::Format resulted in a general protection (GP) fault if variable width or precision specifiers were used. Format did not correctly handle variable width or precision parameters, such as %*d, which caused an Access Violation.
• The tab control didn't invalidate after adding a tab to a property sheet. If you added a CPropertyPage via CPropertySheet::AddPage while the CPropertySheet was displayed, the tab control did not update to reflect the change. The tab control needed to be invalidated. This is similar to the behavior of CTabControl::RemoveTab.
• When the last control on a property page had the WS_TABSTOP style, but was hidden, tabbing from the next-to-last control jumped to the first control on the page. The expected behavior would be to go to the first control on the associated property sheet (usually below the property pages). Note that the correction for this behavior does not affect existing code.
• An edit control in a property page did not get Return keys. A multiline edit control with the ES_WANTRETURN style set did not receive return-key messages (WM_KEYDOWN with VK_RETURN) when placed in a CPropertyPage object. If the parent CPropertySheet object contained a button with an ID that was IDOK, the dialog box was dismissed when the return key was pressed in the edit control. For more information, please see the following article in the Microsoft Knowledge Base:

  125645 FIX: Edit Control in Property Page Does Not Get Return Keys

• Problems occurred after destroying a dockable CControlBar object. When the CControlBar object was destroyed, its destructor did not remove the control bar from an array of control bar pointers kept by MFC in a CDockBar object. In some situations, this led to an exception caused by an Access Violation in the function CObject::IsKindOf. For more information, please see the following article in the Microsoft Knowledge Base:

  125728 FIX: Problems Occur After Destroying Dockable CControlBar

• In applications that called CFrameWnd::LoadBarState, restoring the docking state resulted in a disabled toolbar. If you added code that called LoadBarState and your dockable toolbar did not have the style CBRS_DOCKMULTI, LoadBarState caused the toolbar to be disabled the next time you ran the application -- if in the previous session, you hid the toolbar while it was floating and closed the application. AppWizard applications do not set this style and do not call LoadBarState, so they did not encounter this problem.
• While being loaded, an MFC _USRDLL could cause an assertion failure if the DLL filename had an extension of fewer than three characters. The assertion, which occurred in CWinApp::SetCurrentHandles, was incorrect. DLL filename extensions are not required to be three characters long, nor must they be "DLL" or any other specific string. However, some environments do require a specific extension, such as the "WLL" extension for Microsoft Word add-ins. This assertion was removed for MFC versions 3.1 and 2.52.
• The implementation for the class CMap template could compare keys incorrectly. The CMap implementation needed to use CompareElements to compare keys. This correction allows greater flexibility in implementing the comparison function.
• Memory could leak in a CMap object when the KEY parameter was of type CString. Removing all elements in the map resulted in deleting only the values stored in the map, not the keys used to look values up. The fix allows greater flexibility in implementing the comparison function.

Fixed Compiler Bugs

• The compiler treated pointer types as the corresponding base type in template specializations. For example, given this template specialization:

        template<class T> T dFriendFunc(Derived<> *);

  char* was treated as char, and int* was treated as int. The compiler did not deduce the template arguments correctly. This caused an error because two functions appeared to differ only in their return types.
• Problems occurred when exceptions were thrown across DLL boundaries. Throwing an object that was exported resulted in an Access Violation. Visual C++ version 2.1 allows you to catch object defined in a DLL outside the context of the defining DLL. For more information, please wee the following article in the Microsoft Knowledge Base:

  122303 BUG: __declspec(dllimport) Classes Are Not Caught Correctly

• The Compiler returned no warning on an attempt to return a temporary variable from a function. For example:

        int a = 5;
        return &a;

  The compiler shipped with Visual C++ version 2.1 now issues a warning' for the return value.

Fixed Linker Bugs

• LineNum information was incorrect when converting from 32-bit Object Module Format (OMF) to Common Object File Format (COFF). The linker incorrectly converted 32-bit OMF LINENUM records to COFF. This showed up in the debugger as incorrect line numbers; the conversion is now correct. For more information, please wee the following article in the Microsoft Knowledge Base:

  117796 PRB: Incorrect Debug Information in 32-bit Object Module

• An error occurred in the incremental linker when processing large images but few relocations. This condition resulted in this message:
  ***** Linker INTERNAL ERROR during EmitRelocations *****
  The problem leading to this message has been corrected.

Fixed Run-Time Library Bugs

• The tolower and toupper functions were not locale sensitive on the Intel platform. The functions incorrectly used the "C" locale regardless of what the locale was.
• Using a pointer to a virtual base class object while catching an exception resulted in an Application Error when the derived class used multiple inheritance. This has been corrected.
• An incorrect heap region size was set under Win32s. Win32s initially did not support reserved but uncommitted virtual memory. A code check in Visual C++ used to limit the maximum total size of the CRTL heap under Win32s. This check has been removed, so applications running under Win32s or Phar Lap TNT will be able to allocate approximately as much total memory as under Windows NT or Windows 95. The initial heap regions will be smaller under Win32s or Phar Lap TNT than under Windows NT or Windows 95.
• The _ecvt function returned the wrong number of digits in the overflow case. If you called _ecvt asking for n digits and the function overflowed, it returned n+1 digits. For example, _ecvt returned 1000 instead of 100. If your code expected three digits, it might use 000, the last three of the four digits returned, instead of 100.
• There was a memory leak in the client DLLs of MSVCRT20.DLL. Suppose EXAMPLE.DLL was a client of MSVCRT20.DLL and a client .EXE loaded and unloaded EXAMPLE.DLL a number of times. The failure in Visual C++ to deallocate a small block of memory in MSVCRT20.DLL could lead to a memory leak.

Fixed Resource Compiler Bugs

• The Resource Compiler required 16 megabytes of virtual memory on startup. This requirement forced you to close applications or increase the size of the Windows swap file to allow the resource compiler to load. A new version of the resource compiler reduces this requirement.