volatile [was: GCC warnings for unused global variables]

[Gabriel Dos Reis]

Fergus Henderson <fjh@cs.mu.OZ.AU> writes:

| On 04-May-2003, Michael Eager <eager@eagercon.com> wrote:
| > I don't believe there is any requirement that static variables are
| > first set to zero and then set their initial value.
| 
| C++98 8.5 [dcl.init] paragraph 6: "The memory occupied by any object
| of static storage duration shall be zero-initialized at program startup
| before any other initialization takes place.".

Which is different from your earlier claim that the *object* is
zero-initialized. 

| > They can be
| > created with the initialized value, if that can be calculated at
| > compile time (e.g., if there is no constructor).
| 
| That is true for non-volatile variables, but only because the compiler
| can apply the as-if rule.  As discussed earlier in this thread, the
| as-if rule does not apply to volatile variables -- the standard prohibits
| implementations from optimizing away accesses to volatile variables.

You keep repeating this false assertion:  Quotes have been to specific
text where the standard does actually permit such optimization.

-- Gaby