Extend support for handling of optional source code parts

[elfring]

The Coccinelle software provides the search operator "question mark". If I try a small script for the semantic patch language out on a source file like the following, I get an incomplete analysis result.

show_variable_definitions1.cocci:

@variable_definition@
expression value;
identifier var;
type data_type;
@@
*data_type var
?= value
 ;

optional_initialisation1.c:

#include <stdio.h>

int main(void)
{
 char const message[] = "Test example\n";
 int result;

 result = puts(message);
 return result;
}

Output:

elfring@Sonne:~/Projekte/Coccinelle/janitor> spatch.opt -sp-file show_variable_definitions1.cocci ../Probe/optional_initialisation1.c
init_defs_builtins: /usr/local/lib64/coccinelle/standard.h
HANDLING: ../Probe/optional_initialisation1.c
diff = 
warning: incompatible arity found on line 7
warning: incompatible arity found on line 6
warning: incompatible arity found on line 6
--- ../Probe/optional_initialisation1.c
+++ /tmp/cocci-output-30894-5c6d7c-optional_initialisation1.c
@@ -2,7 +2,6 @@

 int main(void)
 {
- char const message[] = "Test example\n";
  int result;

  result = puts(message);

I hope that the mentioned arity can become compatible. It seems that SmPL disjunctions need to be used instead for a while.

show_variable_definitions2.cocci:

@variable_definition@
expression value;
identifier var;
type data_type;
@@
(
*data_type var;
|
*data_type var = value;
)

Output:

elfring@Sonne:~/Projekte/Coccinelle/janitor> spatch.opt -sp-file show_variable_definitions2.cocci ../Probe/optional_initialisation1.c
init_defs_builtins: /usr/local/lib64/coccinelle/standard.h
HANDLING: ../Probe/optional_initialisation1.c
diff = 
--- ../Probe/optional_initialisation1.c
+++ /tmp/cocci-output-32184-d244bd-optional_initialisation1.c
@@ -2,8 +2,6 @@

 int main(void)
 {
- char const message[] = "Test example\n";
- int result;

  result = puts(message);
  return result;

I hope that the software implementation can also be improved around the operator "question mark" so that search element duplication can be avoided in more use cases.