DOCUMENT:Q79146  04-MAY-2001  [masm]
TITLE   :FIX: MASM 6.0 Generates L1103 for Nested Structures
PRODUCT :Microsoft Macro Assembler
PROD/VER::6.0
OPER/SYS:
KEYWORDS:

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

 - Microsoft Macro Assembler (MASM), version 6.0 
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SYMPTOMS
========

The Microsoft Macro Assembler (MASM) version 6.0 may produce an invalid object
file, generating the following error message at link time:

   fatal error L1103: attempt to access data outside segment bounds

The error occurs when a number of nested UNIONS and STRUCTURES are used.

RESOLUTION
==========

A work around is to rearrange the order of the outer-most structure. The sample
code below illustrates this.

STATUS
======

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

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

The sample code below illustrates this problem. If the MASM switch /Fl is used
to generate a listing file, it can be seen that the assembler generates an
offset for "BAD" of 001E in the structure ST1. Because this structure is a copy
of the previous structure (ST0), the offset for BAD in each structure should be
the same, the correct offset is 0014. No assembler error or warning is
generated, but when the .OBJ file is linked, the L1103 error is generated.

Note: In the file listing, an incorrect offset is generated, but in the symbol
listing, a correct offset is displayed for both instances of BAD.

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

   ; Rearranging ST1 as indicated in the comments fixed the problem in ST1
   ; for this sample code.

   ; Assemble options needed: none
   ; (use /Fl to generate listing file)

   .MODEL small
   .STACK 4096

   ST0  STRUCT
      UNION
         STRUCT
            A       BYTE 10 DUP ('A')
            UNION
               B    BYTE 10 DUP ('B')
               D    BYTE 10 DUP ('D')
            ENDS
         ENDS
         E          BYTE 10 DUP ('E')
      ENDS
      BAD    BYTE   (' ')
   ST0  ENDS

   ST1  STRUCT                        ; ST1  STRUCT
      UNION                           ;    BAD    BYTE   (' ')
         E          BYTE 10 DUP ('E') ;    UNION
         STRUCT                       ;       E          BYTE 10 DUP ('E')
            A       BYTE 10 DUP ('A') ;       STRUCT
            UNION                     ;          A       BYTE 10 DUP ('A')
               B    BYTE 10 DUP ('B') ;          UNION
               D    BYTE 10 DUP ('D') ;             B    BYTE 10 DUP ('B')
            ENDS                      ;             D    BYTE 10 DUP ('D')
         ENDS                         ;          ENDS
      ENDS                            ;       ENDS
      BAD    BYTE   (' ')             ;    ENDS
   ST1  ENDS                          ; ST1  ENDS

   .DATA

   item1   ST0    <>
   item2   ST1    <>

   .CODE
       .startup
       .exit 0
   END

Additional query words: s_link 6.00 buglist6.00 fixlist6.00a

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM600
Version           : :6.0
Solution Type     : kbfix

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

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