Can't Resolve External Symbol When Subtracting

[David Daney]

Anthony DeRosa wrote:
> Is this the wrong mailing list for the question I posted yesterday,
> repeated below?
> 

It is the correct list.

> Thanks,
> Anthony
> 
> 
>>>>"Anthony DeRosa" <ADEROSA@evitechnology.com> 10/26/2006 10:32 am
>>>>
> 
> 
> After recently upgrading from binutils 2.15.90 to binutils 2.17, I get
> the following error with the following code:
>  
> #-------------- code snippet ---------------------------------
> .extern external_symbol
>  
> local_symbol_0:
>     .half 0x1234
>  
> local_symbol_1:
>     .half 0x5678
>  
> some_table:
>  
>     # this *does* work
>     .word external_symbol
>  
>     # this *does* work
>     .word local_symbol_0 - local_symbol_1
>  
>     # this does *not* work
>     .word external_symbol - local_symbol_0
> 
>  
> #-------------- reported error ---------------------------------
> $ mips-elf-as test.S 
> test.S: Assembler messages:
> test.S:8: Error: can't resolve `external_symbol' {*UND* section} -
> ``local_symbol_0' {.text section}
>  
> #------------------------------------------------------------------
>  
> This error did not occur with the previous version of binutils.  Why
> does this no longer work?  What is the workaround?
>  

I believe the answer is: That Binutils was 'Improved' so that you can no 
longer take the difference between symbols that may be in different 
sections.

As far as I know there are only the obvious workarounds:

1) Change your code.

2) Use a version of Binutils that works with your code.

3) Modify Binutils so that you can once again do what your program does.

David Daney.