coccinelle: semantic patch converting 0 test to null test

/// Compare pointer-typed values to NULL rather than 0

///

//# This makes an effort to choose between !x and x == NULL.  !x is used

//# if it has previously been used with the function used to initialize x.

//# This relies on type information.  More type information can be obtained

//# using the option -all_includes and the option -I to specify an

//# include path.

//

// Confidence: High

// Copyright: (C) 2012 Julia Lawall, INRIA/LIP6.  GPLv2.

// Copyright: (C) 2012 Gilles Muller, INRIA/LiP6.  GPLv2.

// URL: http://coccinelle.lip6.fr/

// Comments:

// Options:

virtual patch

virtual context

virtual org

virtual report

@initialize:ocaml@

let negtable = Hashtbl.create 101

@depends on patch@

expression *E;

identifier f;

@@

(

  (E = f(...)) ==

- 0

+ NULL

|

  (E = f(...)) !=

- 0

+ NULL

|

- 0

+ NULL

  == (E = f(...))

|

- 0

+ NULL

  != (E = f(...))

)

@t1 depends on !patch@

expression *E;

identifier f;

position p;

@@

(

  (E = f(...)) ==

* 0@p

|

  (E = f(...)) !=

* 0@p

|

* 0@p

  == (E = f(...))

|

* 0@p

  != (E = f(...))

)

@script:python depends on org@

p << t1.p;

@@

coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0")

@script:python depends on report@

p << t1.p;

@@

coccilib.report.print_report(p[0], "WARNING comparing pointer to 0")

// Tests of returned values

@s@

identifier f;

expression E,E1;

@@

 E = f(...)

 ... when != E = E1

 !E

@script:ocaml depends on s@

f << s.f;

@@

try let _ = Hashtbl.find negtable f in ()

with Not_found -> Hashtbl.add negtable f ()

@ r disable is_zero,isnt_zero exists @

expression *E;

identifier f;

@@

E = f(...)

...

(E == 0

|E != 0

|0 == E

|0 != E

)

@script:ocaml@

f << r.f;

@@

try let _ = Hashtbl.find negtable f in ()

with Not_found -> include_match false

// This rule may lead to inconsistent path problems, if E is defined in two

// places

@ depends on patch disable is_zero,isnt_zero @

expression *E;

expression E1;

identifier r.f;

@@

E = f(...)

<...

(

- E == 0

+ !E

|

- E != 0

+ E

|

- 0 == E

+ !E

|

- 0 != E

+ E

)

...>

?E = E1

@t2 depends on !patch disable is_zero,isnt_zero @

expression *E;

expression E1;

identifier r.f;

position p1;

position p2;

@@

E = f(...)

<...

(

* E == 0@p1

|

* E != 0@p2

|

* 0@p1 == E

|

* 0@p1 != E

)

...>

?E = E1

@script:python depends on org@

p << t2.p1;

@@

coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0, suggest !E")

@script:python depends on org@

p << t2.p2;

@@

coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0")

@script:python depends on report@

p << t2.p1;

@@

coccilib.report.print_report(p[0], "WARNING comparing pointer to 0, suggest !E")

@script:python depends on report@

p << t2.p2;

@@

coccilib.report.print_report(p[0], "WARNING comparing pointer to 0")

@ depends on patch disable is_zero,isnt_zero @

expression *E;

@@

(

  E ==

- 0

+ NULL

|

  E !=

- 0

+ NULL

|

- 0

+ NULL

  == E

|

- 0

+ NULL

  != E

)

@ t3 depends on !patch disable is_zero,isnt_zero @

expression *E;

position p;

@@

(

* E == 0@p

|

* E != 0@p

|

* 0@p == E

|

* 0@p != E

)

@script:python depends on org@

p << t3.p;

@@

coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0")

@script:python depends on report@

p << t3.p;

@@

coccilib.report.print_report(p[0], "WARNING comparing pointer to 0")