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Q110002: FIX: Combining -4Yb with -Ox May Cause Invalid Run-Time Errors

Article: Q110002
Product(s): Microsoft Fortran Compiler
Version(s): 1.0,1.0a
Operating System(s): 
Keyword(s): kbCompiler kbFL32 kbFortranPSkbbuglist kbfixlist
Last Modified: 24-MAR-2000

-------------------------------------------------------------------------------
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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