Q32762: FIX: Forward Reference to Segment Name Gives Phase Error

Article: Q32762
Product(s): Microsoft Macro Assembler
Version(s): 5.1,5.1a
Operating System(s): 
Keyword(s): 
Last Modified: 06-MAY-2001

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The information in this article applies to:

- Microsoft Macro Assembler (MASM), versions 5.1, 5.1a 
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SYMPTOMS
========

A forward reference to a segment name in the Microsoft Macro Assembler (MASM)
versions 5.0, 5.1, and 5.1a will incorrectly cause the following error to occur

  error A2006: phase error between passes

RESOLUTION
==========

A workaround is to declare empty segments at the top of your MASM source code,
defining all segments in the order needed.

STATUS
======

Microsoft has confirmed this to be a problem in MASM versions 5.1 and 5.1a. This
problem was corrected in MASM version 6.0.

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

The following source example demonstrates the problem. As a work around, place
the following code fragment at the top of the source file.

        CSEG segment para public 'CODE'
        CSEG ends
        SSEG segment stack 'STACK'
        SSEG ends

Because the sseg segment is declared before the MOV instruction references it,
the phase error is eliminated. The cseg segment is also declared to ensure that
the ordering of the two segments is unchanged.

Note that this problem does not occur with MASM 6.0 or later since phase errors
are only generated by two pass assemblers and MASM 6.0 and later are N-pass
assemblers.

Sample Code:
------------

  ;Assemble options needed: none

  cseg SEGMENT para public 'CODE'
       assume cs:cseg

  main PROC near
       MOV bx, seg sseg               ;will generate phase error
       RET
  main ENDP

  cseg ENDS

  sseg SEGMENT stack 'STACK'
       db 100h dup(?)
  sseg ENDS

  END main

Additional query words: 5.00 5.10 5.10a buglist5.10 buglist5.10a fixlist6.00

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Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM510 kbMASM510a
Version           : :5.1,5.1a
Solution Type     : kbfix

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