linux-kernel - Re: [PATCH v2] checkpatch: Suggest using min_t or max

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Date:	Wed, 05 Sep 2012 10:07:11 -0700
From:	Joe Perches <joe@...ches.com>
To:	Philippe De Muyter <philippe.demuyter@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Whitcroft <apw@...onical.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] checkpatch: Suggest using min_t or max_t

On Wed, 2012-09-05 at 13:21 +0200, Philippe De Muyter wrote:
> On 5/27/11, Joe Perches <joe@...ches.com> wrote:
> > A common issue with min() or max() is using a cast on
> > one or both of the arguments when using min_t/max_t could
> > be better.
> >
> > Add cast detection to uses of min/max and suggest an
> > appropriate use of min_t or max_t instead.
> >
> > Caveat:  This only works for min() or max() on a single line.
> >          It does not find min() or max() split across multiple lines.
> >
> > This does find:
> > 	min((u32)foo, bar);
> > But it does not find:
> > 	max((unsigned long)foo,
> > 	    bar);
> >
> > Suggested-by: Andrew Morton <akpm@...ux-foundation.org>
> > Signed-off-by: Joe Perches <joe@...ches.com>
> > ---
> >
> > v2: Make $match_balanced_parentheses work in perl 5.8
> 
> Has this been applied  ?
> 
> v3.3 version of checkpatch.pl works for me, but v3.4, v3.5 & v3.6rc2 say:
> Nested quantifiers in regex; marked by <-- HERE in m/(\((?:[^\(\)]++
> <-- HERE |(?-1))*\))/ at scripts/checkpatch.pl line 340.
> 
> and my perl is :
> 
>         perl --version
> 
>         This is perl, v5.8.8 built for i586-linux-thread-multi

The current version of checkpatch skips this
check when the perl version is less than 5.10.0


commit d7c76ba7e58bc3ca674f20759c686535db484749
Author: Joe Perches <joe@...ches.com>
Date:   Tue Jan 10 15:09:58 2012 -0800

    checkpatch: improve memset and min/max with cast checking
    
    Improve the checking of arguments to memset and min/max tests.
    
    Move the checking of min/max to statement blocks instead of single line.
    Change $Constant to allow any case type 0x initiator and trailing ul
    specifier.  Add $FuncArg type as any function argument with or without a
    cast.  Print the whole statement when showing memset or min/max messages.
    Improve the memset with 0 as 3rd argument error message.
    
    There are still weaknesses in the $FuncArg and $Constant code as arbitrary
    parentheses and negative signs are not generically supported.

[]
# Using $balanced_parens, $LvalOrFunc, or $FuncArg
# requires at least perl version v5.10.0
# Any use must be runtime checked with $^V
[]
# typecasts on min/max could be min_t/max_t
		if ($^V && $^V ge 5.10.0 &&
		    defined $stat &&
		    $stat =~ /^\+(?:.*?)\b(min|max)\s*\(\s*$FuncArg\s*,\s*$FuncArg\s*\)/) {


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