Re: [Cocci] Checking redundant variable initialisations with SmPL?

[Markus Elfring <Markus.Elfring@web.de>]

> Yu can do whatever you want, but you will get lotsof false positives if
> you keep it.  If you really want a star on the declaration then you need
> to make two rules.  The first that finds the positions of the places that
> match and the second that only puts a * when there is both a matched
> declaration and a matched reinitialization.

I hoped that the following SmPL script variant can be another approximation
for the desired solution on the discussed source code search pattern.


@display@
binary operator bo1, bo2;
expression action, e1, e2 != e1, e3, e4, e5;
identifier var;
statement es1, is2, es2, is3, es3;
type t;
@@
(
 t var = e1;
 <+...
 if (...)
 {
    var = e2;
    ...
 }
 else
    es1
 ...+>
 if ( \( var \| var bo1 e3 \) )
    is2
 else
    es2
|
 t var
*      = e1
 ;
 ... when != if ( \( var \| var bo2 e4 \) ) is3 else es3
     when != action(..., var, ...)
     when != switch (var) { default: ... }
     when exists
(
*e5 = <+... var ...+>
|
*var = e5
)
)


But I stumble on the following error message.

elfring@Sonne:~/Projekte/Linux/next-patched> git checkout next-20190620 && spatch drivers/misc/lkdtm/core.c ~/Projekte/Coccinelle/janitor/show_questionable_variable_initialisation5.cocci
…
minus: parse error:
  File "/home/elfring/Projekte/Coccinelle/janitor/show_questionable_variable_initialisation5.cocci", line 36, column 0, charpos = 492
  around = ')',
  whole content = )


I observed then that each of the two main branches in the shown SmPL disjunction
can work as expected. So I wonder even more why the combination can not be parsed
by the software “Coccinelle 1.0.7-00211-geaa13d59 (OCaml 4.07.1)” so far.

Regards,
Markus
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