Re: [PATCH] rcu: remove unused variable in boot_cpu_state_init

From: Ingo Molnar
Date: Thu Jun 22 2017 - 03:51:12 EST

* Arnd Bergmann <arnd@xxxxxxxx> wrote:

> > So I think we should consider it a syntactic construct to avoid.
> Unused variables are relatively harmless compared to used-uninitialized
> variables that are always bugs (though they are provably impossible to
> detect correctly in some cases).

So the thing I was most worried about was that old GCC used to not warn about:

long __maybe_unused error;


if (error)
return error;

... but recent GCC does warn if it's certain that the use is uninitialized, so the
scenario I outlined should not happen.

But it will supress the warning if the variable is uninitialized but GCC cannot
prove it for sure, so my point remains that it's a potentially dangerous