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Subject: Re: [Cake] [PATCH] net/sch_generic.h: use sizeof_member() and get
 rid of unused variable
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From: Antonio Quartulli <a@unstable.cc>
Date: Wed, 20 May 2020 10:39:33 +0200

> I don't think it's BUILD_BUG_ON()'s fault, because qcb->data is passed
> to sizeof() first.
> 
> My best guess is that gcc is somewhat optimizing the sizeof(gcb->data)
> and thus leaving the gcb variable unused.

If you remove the argument from the function but leave the BUILD_BUG_ON()
calls the same, the compilation will fail.

Any such optimization is therefore unreasonable.

The variable is used otherwise compilation would not fail when you
remove it right?