cvs commit: src/sys/kern subr_bus.c

[Nate Lawson]

On Wed, 24 Mar 2004, Julian Elischer wrote:
> On Wed, 24 Mar 2004, David Schultz wrote:
>
> > On Mon, Mar 22, 2004, David O'Brien wrote:
> > > On Mon, Mar 22, 2004 at 06:06:48PM -0800, Nate Lawson wrote:
> > > > > +			if (bootverbose && flags & INTR_MPSAFE)
> > > ..
> > > > I recommend you parenthesize (flags & INTR_MPSAFE).
> > >
> > > man operator  :-)
> >
> > For some reason, gcc complains about the lack of excessive
> > parentheses for expressions like 'a && b || c' and
> > 'foo >> shift1 + shift2', but not for 'a && b & c'.
> > It's too bad there's no documentation on which parts of
> > operator(7) are supposed to be considered obvious (along
> > with a note that =='s priority over & is a mistake---that
> > one often bites me.)
> >
>
> I agree. it is often late at night when staring at code looking for a
> bug that one fails to notice the subtlties of operator precedence.
>
> One person's "obvious" is not always obvious to others. Especially if
> one has noticed differences in precedence between different languages
> one has worked with in one's life.
>
> a couple of extra parens on a statement with 'non-normal' form
> such as that above can save hours later.

I agree with one exception -- when parens are used in an overly obvious
way (like MDAS) or in an attempt to force precedence (which they cannot
do.)  Parens only indicate associativity, they cannot override precedence.

-Nate