DOCUMENT:Q149516  02-NOV-1999  [fortran]
TITLE   :BUG: Watching a DLL Common Block Using Context Operator Fails
PRODUCT :Microsoft Fortran Compiler
PROD/VER::4.0
OPER/SYS:
KEYWORDS:kbDebug kbidekbbuglist

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

 - Microsoft Fortran PowerStation for Windows 95 and Windows NT, version 4.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

Attempting to view a DLL variable or common block contents in a watch window
using the context operator {} fails with the following messages:

DLL variable:

   "EE2347: Undefined variable"

DLL common block:

   "Invalid Debug Information"

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. We are researching this problem and will post new
information here in the Microsoft Knowledge Base as it becomes available.

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

Debug information for DLL variables and common blocks is available in the
debugger's Locals window. The members of a common block can be viewed in a watch
window but only if specified without the context operator. Trying to view a DLL
variable or common block by using the context operator will always fail. Also,
attempting to watch a common block structure in a watch window will fail with
the message "Invalid Debug Information".

Steps to Reproduce Problem
--------------------------

1. Create two source code files using the sample code provided. One (Theapp.for)
   will be the main source code and the other (Thedll.for) will be the DLL
   source code.

2. Create a QuickWin project using the main source file (Theapp.for). From the
   Developer Studio File menu, choose New, and then double-click the Project
   Workspace option. In the New Project Workspace dialog box, click the QuickWin
   Application type, name the project TheApp, set the project directory, and
   click the Create button.

3. Insert the main source code file into the project. From the Insert menu,
   choose Files into Project. and select the Theapp.for file.

4. Create a DLL project using the file Thedll.for, which will be a subproject of
   the QuickWin project created in step 2. From the Insert menu, choose Project,
   and then in the Insert Project dialog box, click the Dynamic-Link Library
   type, name the project TheDll, click Subprojects of:, and click the Create
   button.

5. Insert the DLL source code file into the subproject. From the Insert menu,
   choose Files into Project, and select the Thedll.for file.

6. Set the DLL build output directory to be the same as the QuickWin build
   output directory. From the Build menu, choose Settings, and then select the
   General folder tab. In the Settings For list box, highlight the DLL debug
   project target "TheDll - Win32 Debug (TheDll.dll)." Then select the Output
   files edit box, and remove the "TheDll\Debug" text, replacing it with
   "Debug." Then click the OK button to save the changes and exit the dialog
   box.

7. Build and link the QuickWin and DLL projects. In Developer Studio, change the
   default configuration to "TheApp - Win32 Debug." Then from the Build menu,
   choose Rebuild All.

8. Try to view the common block or its members in a watch window. Begin a
   debugging session, from the Build menu, choose Debug, and then select Step
   Into. Step past the variable initialization statements in the DLL. Now, in a
   watch window, type the variable "i" or the common block name "TheBlock" using
   the context operator as in the following examples and press the ENTER key.

   Example One
   -----------

   Type:

   " {,,TheDll.dll}i" (without the quotation marks)

   Result:

   This fails with "EE2347: Undefined variable"

   Example Two
   -----------

   Type:

   " {,,TheDll.dll}TheBlock" (without the quotation marks)

   Result:

   This fails with "Invalid Debug Information"

Sample Code
-----------

Main:

   C Compile options needed: /MW /Zi
   C TheApp.for (QuickWin app)
         program TheApp
             integer i, j
             common /TheBlock/ i, j
             !ms$attributes dllimport :: TheBlock
             call initcommon()
             print *, i, j
         end

DLL:

   C Compile options needed: /LD /Zi
   C TheDll.for (DLL for TheApp)
         subroutine initcommon()
             !ms$attributes dllexport :: initcommon
             integer i, j
             common /TheBlock/ i, j
             !ms$attributes dllexport :: TheBlock
             i = 5
             j = 7
         end

Additional query words: 4.00

======================================================================
Keywords          : kbDebug kbide kbbuglist
Technology        : kbAudDeveloper kbPTProdChange kbFortranSearch kbFORTRANPower400NT
Version           : :4.0

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1999.