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Q76911: FIX: JMP Jumps to the Proc When Using Duplicate Names

Article: Q76911
Product(s): Microsoft Macro Assembler
Version(s): MS-DOS:6.0,6.0a,6.0b
Operating System(s): 
Keyword(s): 
Last Modified: 06-MAY-2001

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

- Microsoft Macro Assembler (MASM), versions 6.0, 6.0a, 6.0b 
-------------------------------------------------------------------------------

SYMPTOMS
========

Using the Microsoft Macro Assembler (MASM) versions 6.0, 6.0a or 6.0b, the JMP
instruction will jump to the procedure name rather than a local label if the
names of the procedure and the local label are identical. After the jump, the
procedure begins running rather than the code at the label.

RESOLUTION
==========

To work around the problem, create a local label with a name that is different
from the procedure name.

STATUS
======

Microsoft has confirmed this to be a problem in MASM versions 6.0, 6.0a, and
6.0b. This problem was corrected in MASM for MS-DOS version 6.1.

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

The sample code below does not generate a syntax error for the identical
procedure name and label name because the label is local to the procedure it is
defined in. If the label is defined with a double colon (::) instead of a single
colon (:), it becomes a global label and causes the assembler to generate an
error. The assembler should generate code that jumps to the local label rather
than the procedure.

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

  ; Assemble options needed: none

  .MODEL small
  .STACK 4096

  .DATA

  .CODE
     .startup
     call myproc
     .exit 0

  myproc PROC
     jmp SHORT mylabel
  mylabel:
     ret  ; Should execute this
  myproc ENDP

  mylabel PROC
     ret  ; Shouldn't execute this
  mylabel ENDP

  END

Additional query words: 6.00 6.00a 6.00b buglist6.00 buglist6.00a buglist6.00b fixlist6.10

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM600 kbMASM600a kbMASM600b
Version           : MS-DOS:6.0,6.0a,6.0b
Solution Type     : kbfix

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