BUG: Invalid A2006 Error Generated by MASM 6.x (107500)

SYMPTOMS

When you attempt to assemble the sample code below, the Microsoft Macro Assembler (MASM) fails and reports the following error for the two lines with "mov" instructions:

error A2006: undefined symbol

RESOLUTION

To work around the problem, do one of the following,

Simplify the expression. If you uncomment the lines in the sample code, and delete the original instructions, the code will assemble without errors. -or-
Assemble with the /Zm option (or run MASM.EXE instead of ML.EXE). -or-
Use the OPTION OLDSTRUCTS directive to have the assembler treat structure members the same as in MASM 5.1.

STATUS

Microsoft has confirmed this to be a problem in MASM versions 6.0x, 6.1, 6.1a, and 6.11. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

Sample Code

; Assemble options needed: none

        .MODEL  small

STEST   STRUCT
  f1    BYTE    ?
  f2    BYTE    ?
STEST   ENDS

        .CODE
        mov     al, SIZEOF STEST.f1 + SIZEOF STEST.f2
        mov     al, LENGTHOF STEST.f1 + LENGTHOF STEST.f2
;
; Uncomment the lines below and delete the two lines above to avoid
; the A2006 error
;
;       temp = SIZEOF STEST.f1
;       mov    al, temp + SIZEOF STEST.f2
;       temp = LENGTHOF STEST.f1
;       mov    al, temp + LENGTHOF STEST.f2

        END