From: Nicholas Mc Guire <der.herr@hofr.at>
To: Cocci@systeme.lip6.fr
Subject: [Cocci] RFC catching hidden code in if conditions
Date: Mon, 25 Mar 2019 14:03:58 +0100 [thread overview]
Message-ID: <20190325130358.GA7492@osadl.at> (raw)
HI !
Noticed that the nuveau driver uses a fair number of if (var=val,boolean-condition){}
which while legal C-code just makes it hard to read - and some seems buggy
actually. The below spatch find about 50 cases - not sure though if this is
actually complete ?
thx!
hofrat
/// Check for unconditional code "hiding" in an if condition
/// effectively that code is unconditionally executed before
/// reaching the actual branch statement - which just makes it
/// hard to read and thus is always wrong.
/// Some of the cases found also look buggy
/// In other cases some excess () are left in place in the
/// generated patches - so some postprocessing may be needed.
///
/// As of 5.0-rc8 all 50 cases look like they are found and fixed
/// correctly - incorrectly only in the sense that the patched
/// code is equivalent to the original code. but as this is in
/// the nouveau driver only it might well be that this only
/// fits that specific pattern and others might have wilder ways
/// to achieve the same - so confidence Low for now
///
// Confidence: Low
// Comments:
// Options: --no-includes --include-headers
virtual patch
virtual report
@badif@
position p;
statement S;
expression E1,E2;
@@
if@p (E1,E2) S
@script:python depends on report@
p << badif.p;
@@
msg = "unconditional code hiding in if condition"
coccilib.report.print_report(p[0],msg)
@fixbadif depends on badif && patch@
position p=badif.p;
statement S;
expression E1=badif.E1,E2=badif.E2;
@@
+ E1;
if@p (
- E1,
E2)
S
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next reply other threads:[~2019-03-25 13:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 13:03 Nicholas Mc Guire [this message]
2019-03-25 13:14 ` [Cocci] RFC catching hidden code in if conditions Julia Lawall
2019-03-26 19:04 ` Markus Elfring
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