[Python-Dev] Update PEP 7 to require curly braces in C

[David Malcolm]

On Mon, 2016-01-18 at 19:18 -0500, Terry Reedy wrote:
> On 1/18/2016 6:20 PM, Brett Cannon wrote:
> >
> >
> > On Sun, 17 Jan 2016 at 11:10 Brett Cannon <brett at python.org
> > <mailto:brett at python.org>> wrote:
> >
> >     While doing a review of http://bugs.python.org/review/26129/ I asked
> >     to have curly braces put around all `if` statement bodies. Serhiy
> >     pointed out that PEP 7 says curly braces are optional:
> >     https://www.python.org/dev/peps/pep-0007/#id5. I would like to
> >     change that.
> >
> >     My argument is to require them to prevent bugs like the one Apple
> >     made with OpenSSL about two years ago:
> >     https://www.imperialviolet.org/2014/02/22/applebug.html. Skipping
> >     the curly braces is purely an aesthetic thing while leaving them out
> >     can lead to actual bugs.
> >
> >     Anyone object if I update PEP 7 to remove the optionality of curly
> >     braces in PEP 7?
> >
> >
> > Currently this thread stands at:
> >
> > +1
> >    Brett
> >    Ethan
> >    Robert
> >    Georg
> >    Nick
> >    Maciej Szulik
> > +0
> >    Guido
> > -0
> >    Serhiy
> >    MAL
> > -1
> >    Victor (maybe; didn't specifically vote)
> >    Larry
> >    Stefan
> 
> Though I don't write C anymore, I occasionally read our C sources.  I 
> dislike mixed bracketing in a multiple clause if/else statement,  and 
> would strongly recommend against that.  On the other hand, to my 
> Python-trained eye, brackets for one line clauses are just noise.  +-0.
> 
> If coverity's scan does not flag the sort of misleading bug bait 
> formatting that at least partly prompted this thread
> 
> if (a):
>     b;
>     c;
> 
> then I think we should find or write something that does and run it over 
> existing code as well as patches.

FWIW, for the forthcoming gcc 6, I've implemented a new
-Wmisleading-indentation warning that catches this.  It's currently
enabled by -Wall:

sslKeyExchange.c: In function 'SSLVerifySignedServerKeyExchange':
sslKeyExchange.c:631:8: warning: statement is indented as if it were guarded by... [-Wmisleading-indentation]
        goto fail;
        ^~~~
sslKeyExchange.c:629:4: note: ...this 'if' clause, but it is not
    if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0)
    ^~


(not that I've had time for core Python development lately, but FWIW in
gcc-python-plugin I mandate braces for single-statement clauses).

Dave