[Cocci] Combining isomorphisms with source code adjustments?

[Cocci] Combining isomorphisms with source code adjustments?

[Markus Elfring]

Hello,

I have taken another look at the following information.
https://github.com/coccinelle/coccinelle/blob/6b4bb692f208bfe86e62a616724570d9310c7150/standard.iso#L544

…
// Affectation/initialisation isomorphism
…
// They are handled in engine.
// 'X = Y'  should also match  'type X = Y';
…


I have tried another script out for the semantic patch language.

@deletion@
expression input, storage, target;
@@
 storage
-        = input
 ... when != storage
 target = ...


elfring@Sonne:~/Projekte/Coccinelle/janitor> spatch --parse-cocci delete_unused_value4.cocci
…
the simple assignment expression on line 4 contains transformations
that prevent it from matching a declaration (not pure)
…


How do you think about the software situation?

Regards,
Markus
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Re: [Cocci] Combining isomorphisms with source code adjustments?

[Julia Lawall]

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On Wed, 22 Apr 2020, Markus Elfring wrote:

> Hello,
>
> I have taken another look at the following information.
> https://github.com/coccinelle/coccinelle/blob/6b4bb692f208bfe86e62a616724570d9310c7150/standard.iso#L544
>
> …
> // Affectation/initialisation isomorphism
> …
> // They are handled in engine.
> // 'X = Y'  should also match  'type X = Y';
> …
>
>
> I have tried another script out for the semantic patch language.
>
> @deletion@
> expression input, storage, target;
> @@
>  storage
> -        = input
>  ... when != storage
>  target = ...
>
>
> elfring@Sonne:~/Projekte/Coccinelle/janitor> spatch --parse-cocci delete_unused_value4.cocci
> …
> the simple assignment expression on line 4 contains transformations
> that prevent it from matching a declaration (not pure)
> …
>
>
> How do you think about the software situation?

I think what the message says.  You have put a - in an awkward place so it
may not be able to apply some isomorphisms.

julia

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Re: [Cocci] Combining isomorphisms with source code adjustments?

[Markus Elfring]

>> @deletion@
>> expression input, storage, target;
>> @@
>>  storage
>> -        = input
>>  ... when != storage
>>  target = ...
>>
>>
>> elfring@Sonne:~/Projekte/Coccinelle/janitor> spatch --parse-cocci delete_unused_value4.cocci
>> …
>> the simple assignment expression on line 4 contains transformations
>> that prevent it from matching a declaration (not pure)
>> …
>>
>>
>> How do you think about the software situation?
>
> I think what the message says.  You have put a - in an awkward place so it
> may not be able to apply some isomorphisms.

I got the impression that the Coccinelle software can handle changes
together with isomorphisms at other source code places already.

* Why is this functionality restricted here?

* The reported software limitation can trigger undesirable code duplication
  if a corresponding transformation approach would be required so far
  to express extra case distinctions by the means of SmPL disjunctions.

Regards,
Markus
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