GCC warnings for unused global variables

[Toon Moene]

Gabriel Dos Reis wrote:

> I already quoted Linus on volatile, here is something from someone who
> has designed and implemented languages, operating systems and
> simulators:
> 
>   [...] However, I never had strong feeelings about volatile and see
>   no reason to improve on the ANSI C committee's decisions in this area.
>      
>          B. Stroustrup, in D&E

Oh, that's nothing.  For many a year, the draft Fortran 2000 Standard 
already contains a "definition" of VOLATILE - or, as the editor of the 
Standard likes to put it "a standard spelling for indicating 
non-standard behaviour".  Not suprisingly, I caught a subgroup last J3 
meeting discussing something that suspiciously looked like "sequence 
points" because without them, volatile has little meaning.

That's for a language that has been successful without sequence points 
(or volatile) for half a century.

And no, that's not because no operating systems have ever been written 
in it.  Good ol' Fortran 66 had a splendid way of preventing accesses to 
memory being "optimized away":

       COMMON /AAP/ MEM
       ...
       FOO = MEM
       CALL DUMSUB
       FOO = MEM
       ...
       END

As whatever DUMSUB does to MEM is outside the scope of the "processor" 
(compiler/runtime/cpu in Fortran Standardese) this effectively causes 
the MEM access to be performed twice.

[ and don't complain about the cost of a subroutine call - in comparison
   with memory access times that's negligible ]

-- 
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
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