Am 05.09.2011 11:09, schrieb per...@pluto.rain.com:
> Matthias Andree <matthias.and...@gmx.de> wrote:
>>> I agree, but I can think of another valid exception. System with
>>> Hamming correction on the memory, gets a single bit (correctable)
>>> error. Need to rewrite the memory contents to reset all the parity
>>> bits!
>> That's a matter of the EDAC stuff, not the business of applications.
>
> True, but it may explain why clang does not flag "*x = *x;" when it
> does flag "x = x;". A compiler cannot know the context in which the
> compiled code will be used.
And a compiler is free to optimize either away unless the storage class
is "volatile", so the original point stands:
> BTW I agree that an understanding is needed of _why_ the code in
> question was included.
Which waits on the original author.
On the other issue:
> I have seen "x = x;" -- x being a formal
> parameter -- used to prevent an "unused argument" warning in a
> function which did not in fact need the argument in question, but
> had to declare it for uniformity with other functions pointed to
> by the same function pointer type.
The portable and concise solution is to cast unused arguments to void,
as in this example:
int f(int used, int unused) {
(void)unused; // avoids warnings
// ...
// now do something with used
// ...
return 42;
}
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