## BUG: Can't Debug LibMain with VC++ Debugger

Q104240

    1.00 1.50
    WINDOWS
    kbtool kbbuglist

    ----------------------------------------------------------------------
    The information in this article applies to:

     - The Microsoft Visual Workbench included with:
       Microsoft Visual C++ for Windows, versions 1.0 and 1.5
    ----------------------------------------------------------------------

    SYMPTOMS
    ========

    When debugging a Windows dynamic-linked library (DLL) with the Visual
    Workbench debugger, the debugger will not step into LibMain. The
    Visual C++ (VC++) debugger also ignores any breakpoint inside LibMain.

    RESOLUTION
    ==========

    A possible workaround is to add an interrupt 3 call to force the
    debugger to break inside LibMain, and then begin debugging from the
    interrupt 3 call. The code would resemble the following:

       _asm int 3

    The debugger stops at the statement. It is important to perform a
    "restart" of the debugger each time after the program is executed. The
    restart forces the debugger to reload the libraries when you begin
    debugging. Reloading the libraries causes LibMain() to be called.

    An alternative workaround is to use CodeView for Windows. CodeView
    performs correctly when breakpoints are set in LibMain.

    STATUS
    ======

    Microsoft has confirmed this to be a problem in the Visual Workbench
    debugger in Visual C++ for Windows version 1.0. This problem does
    not occur if the DLL is loaded dynamically at run time using the
    Windows function LoadLibrary(). This problem also does not occur in Visual
    C++ 32-bit edition.

    MORE INFORMATION
    ================

    To reproduce the problem, you can set a breakpoint in the SELECT.C
    sample program included in Visual C++. In VC++ 1.0 for Windows, this
    sample is located in C:\MSVC\SAMPLES\SELECT.

    Additional reference words: 1.00 1.50
    KBCategory: kbtool kbbuglist
    KBSubcategory: VWBIss

Keywords : kb16bitonly
Issue type :
Technology :

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