DOCUMENT:Q110002  24-MAR-2000  [fortran]
TITLE   :FIX: Combining -4Yb with -Ox May Cause Invalid Run-Time Errors
PRODUCT :Microsoft Fortran Compiler
PROD/VER::1.0,1.0a
OPER/SYS:
KEYWORDS:kbCompiler kbFL32 kbFortranPSkbbuglist kbfixlist

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

 - Microsoft FORTRAN PowerStation for MS-DOS, versions 1.0, 1.0a 
 - Microsoft Fortran Powerstation 32 for Windows NT, version 1.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

On some rare boundary cases, using optimizations (-Ox) with extended error
handling ($DEBUG or -4Yb) can cause invalid run-time errors to be output, such
as:

   run-time error F6096: $DEBUG
   - array subscript expression out of range

RESOLUTION
==========

If you have determined that a run-time error such as the above is not correct
for the code indicated, you can prevent your program from terminating with the
error. To do this, place a $NODEBUG metacommand before the line of code that is
being flagged, and place a $DEBUG metacommand after it.

STATUS
======

Microsoft has confirmed this to be a problem in FORTRAN PowerStation 32 for
Windows NT and MS-DOS, version 1.0 and 1.0A. This problem was corrected in
FORTRAN PowerStation 32, version 4.0.

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

The sample below illustrates the problem:

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

   c Compile options required: -Ox -4Yb
   c
         CHARACTER CA(512),CB(512),CC(512)
         OPEN(7,FILE='N117.TMP',FORM='UNFORMATTED',RECL=128,
        +     ACCESS='DIRECT')
         DO 10 I=1,512
           CA(I)=CHAR(48)
   10    CONTINUE
         DO 20 I=1,16
           WRITE(7,REC=I) (CA(J),J=(I-1)*32+1,(I-1)*32+32)
   c The F6096 error incorrectly occurs on the following line.
           WRITE(7,REC=16+I) (CA(J),J=(16-I)*32+32,(16-I)*32+1,-1)
   20    CONTINUE
         DO 30 I=1,16
           IE1=(16-I)*32+32
           IE2=(16-I)*32+1
           READ(7,REC=I+16) (CC(J),J=IE1,IE2,-1)
   30    CONTINUE
         IE=1
         DO 40 I=1,512
           IF(CA(I).NE.CB(I).OR.CA(I).NE.CC(I)) IE=0
   40    CONTINUE
         END

Additional query words: 1.00

======================================================================
Keywords          : kbCompiler kbFL32 kbFortranPS kbbuglist kbfixlist
Technology        : kbAudDeveloper kbFortranSearch kbZNotKeyword2 kbZNotKeyword3 kbFORTRANPower32100NT kbFORTRANPower100DOS kbFORTRANPower100aDOS
Version           : :1.0,1.0a
Issue type        : kbbug
Solution Type     : kbfix

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