Re: [PATCH] coccinelle: add style check for assignment in if

From: Julia Lawall
Date: Sat Aug 15 2015 - 13:46:58 EST


My version is below. It adds parentheses in a few more places, and allows
assignments without a binary operator (b) in the && cases.

Also I threw in a case for things like: if (ret = -ENOENT, !data)

Another thing is that the header is not really correct. It should be in
the following format:

/// Short comment of gernal interest
//# More information, eg about potential false positives
///
// Confidence: Moderate
// Copyright: whatever you want, it would be nice to have your name
// URL: http://coccinelle.lip6.fr/
// Comments:
// Options: --no-includes --include-headers

Then you should have:

virtual patch

Otherwise, the kernel infrastructure will not think that the patch mode is
supported. No other changes are needed, since no other modes are
supported. I don't think that supporting other modes is necessary, since
I think that checkpatch complains about this issue too.

julia

------------------------

// find checkpatch.pl errors of the type:
// ERROR: do not use assignment in if condition
//
// This script is designed to correct code where assignments exist in if
// conditions. It is only capable of handling a subset of such problems.
//
// For example:
//
// if(result = myfun())
//
// would become:
//
// result = myfun();
// if(result)
//
// Confidence: Moderate

// if ( (ret = call()) < 0 )
@if2@
expression i;
expression E, E2;
statement S1, S2;
binary operator b;
@@

+ i = E;
if (
(
... b
- (i = E)
+ i
|
- (i = E)
+ i
b ...
|
- (i = E)
+ i
|
- (i = E),
E2
)
) S1 else S2

// if ( ptr->fun && (ret = ptr->fun()) < 0 )
@if3@
expression i2;
expression E1, E2;
constant c;
binary operator b;
@@

+ if( E1 ) {
+ i2 = E2;
+ if (i2 b c) {
- if( E1 && ((i2 = E2) b c) ) {
...
- }
+ }
+ }

// if ( (ret = call()) < 0 && ret != -1 )
@if4@
expression i;
expression E, E2;
statement S1, S2;
binary operator b;
@@

+ i = E;
if (
(
(...
b
- (i = E)
+ i
)
|
(
- (i = E)
+ i
b
...)
|
- (i = E)
+ i
) && E2 ) S1 else S2

// if ( (ret = call()) < 0 && ret != -1 && ret != -2 )
@if5@
expression i;
expression E, E2, E3;
statement S1, S2;
binary operator b;
@@

+ i = E;
if (
(
(...
b
- (i = E)
+ i
)
|
(
- (i = E)
+ i
b
...)
|
- (i = E)
+ i
) && E2 && E3 ) S1 else S2

@@
expression i,e;
statement S1,S2;
@@

if (<+...
-i = e
+BAD
...+>) S1 else S2
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