Re: [PATCH 1/4] compiler.h: introduce unused_expression() macro

[Konstantin Khlebnikov]

Cong Wang wrote:
> On 04/25/2012 07:26 PM, Konstantin Khlebnikov wrote:
> > Sometimes we want to check some expressions correctness in compile-time without
> > generating extra code. "(void)(e)" does not work if expression has side-effects.
> > This patch introduces macro unused_expression() which helps in this situation.
>
> Interesting, I am wondering why gcc doesn't eliminate the code as we
> pass either -O2 or -Os to it.

It cannot do this if expression has some side-effects, for example if it contains BUG().
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