coccinelle: misc: add uninitialized_var.cocci script

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

///

/// Please, don't reintroduce uninitialized_var().

/// From Documentation/process/deprecated.rst:

///  For any compiler warnings about uninitialized variables, just add

///  an initializer. Using warning-silencing tricks is dangerous as it

///  papers over real bugs (or can in the future), and suppresses unrelated

///  compiler warnings (e.g. "unused variable"). If the compiler thinks it

///  is uninitialized, either simply initialize the variable or make compiler

///  changes. Keep in mind that in most cases, if an initialization is

///  obviously redundant, the compiler's dead-store elimination pass will make

///  sure there are no needless variable writes.

///

// Confidence: High

// Copyright: (C) 2020 Denis Efremov ISPRAS

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

//

virtual context

virtual report

virtual org

@r@

identifier var;

type T;

position p;

@@

(

* T var =@p var;

|

* T var =@p *(&(var));

|

* var =@p var

|

* var =@p *(&(var))

)

@script:python depends on report@

p << r.p;

@@

coccilib.report.print_report(p[0],

  "WARNING this kind of initialization is deprecated (https://www.kernel.org/doc/html/latest/process/deprecated.html#uninitialized-var)")

@script:python depends on org@

p << r.p;

@@

coccilib.org.print_todo(p[0],

  "WARNING this kind of initialization is deprecated (https://www.kernel.org/doc/html/latest/process/deprecated.html#uninitialized-var)")