Re: [PATCH v6] kernel.h: Retain constant expression output for max()/min()

[Uecker, Martin]

To give credit where credit is due, this hack was inspired byÂ
an equally insane (but different) use of the ?: operator to chooseÂ
the right return type for type-generic macros in tgmath.h.

https://sourceware.org/git/?p=glibc.git;a=blob;f=math/tgmath.h;h=a709a5
9d0fa1168ef03349561169fc5bd27d65aa;hb=d8742dd82f6a00601155c69bad3012e90
5591e1f

(recommendation: don't look)

Martin


Am Montag, den 26.03.2018, 14:52 -1000 schrieb Linus Torvalds:
> On Mon, Mar 26, 2018 at 12:15 PM, Kees Cook <keescook@xxxxxxxxxxxx>
> wrote:
> > 
> > This patch updates the min()/max() macros to evaluate to a constant
> > expression when called on constant expression arguments.
> 
> Ack.
> 
> I'm of two minds whether that "__is_constant()" macro should be
> explained or not.
> 
> A small voice in my head says "that wants a comment".
> 
> But a bigger voice disagrees.
> 
> It is a work of art, and maybe the best documentation is just the
> name. It does what it says it does.
> 
> Art shouldn't be explained. It should be appreciated.
> 
> Nobody sane really should care about how it works, and if somebody
> cares it is "left as an exercise to the reader".
> 
> ÂÂÂÂÂÂLinus