coccinelle: misc: add flexible_array.cocci script

// SPDX-License-Identifier: GPL-2.0-only

///

/// Zero-length and one-element arrays are deprecated, see

/// Documentation/process/deprecated.rst

/// Flexible-array members should be used instead.

///

//

// Confidence: High

// Copyright: (C) 2020 Denis Efremov ISPRAS.

// Comments:

// Options: --no-includes --include-headers

virtual context

virtual report

virtual org

virtual patch

@initialize:python@

@@

def relevant(positions):

    for p in positions:

        if "uapi" in p.file:

             return False

    return True

@r depends on !patch@

identifier name, array;

type T;

position p : script:python() { relevant(p) };

@@

(

  struct name {

    ...

*   T array@p[\(0\|1\)];

  };

|

  struct {

    ...

*   T array@p[\(0\|1\)];

  };

|

  union name {

    ...

*   T array@p[\(0\|1\)];

  };

|

  union {

    ...

*   T array@p[\(0\|1\)];

  };

)

@depends on patch@

identifier name, array;

type T;

position p : script:python() { relevant(p) };

@@

(

  struct name {

    ...

    T array@p[

-       0

    ];

  };

|

  struct {

    ...

    T array@p[

-       0

    ];

  };

)

@script: python depends on report@

p << r.p;

@@

msg = "WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)"

coccilib.report.print_report(p[0], msg)

@script: python depends on org@

p << r.p;

@@

msg = "WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)"

coccilib.org.print_todo(p[0], msg)