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* [Cocci] Does coccinelle support non-standard C?
@ 2019-05-22 11:28 Christoph Böhmwalder
  2019-05-22 11:37 ` Julia Lawall
  0 siblings, 1 reply; 5+ messages in thread
From: Christoph Böhmwalder @ 2019-05-22 11:28 UTC (permalink / raw)
  To: cocci

Hi,

Consider the following snippet of C:


#define f() ({ puts("hello"); 0; })
int main()
{
     printf("%d\n", f());
}


It uses an expression statement in the definition of `f`, which is a gcc 
extension.

Now let's try to write a semantic patch to generate something like this:


@@
@@
- cocci_replace_this()
+ ({ puts("hello"); 0; })


With the C code as:


#define f() cocci_replace_this()
int main()
{
     printf("%d\n", f());
}


This prompts the following error message from spatch:


$ spatch --sp-file test.cocci test.c
init_defs_builtins: /usr/lib/coccinelle/standard.h
32 33
Fatal error: exception Failure("plus: parse error: \n = File 
\"test.cocci\", line 4, column 3,  charpos = 32\n    around = '{', whole 
content = + ({ puts(\"hello\"); 0; })\n")


Now here's my question: this obviously implies that coccinelle doesn't 
support expression statements (or any other non-standard C for that 
matter). Can I still somehow tell spatch to just replace it with this 
string of text instead of trying to parse it as C?

Thanks.

--
Regards,
Christoph
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^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [Cocci] Does coccinelle support non-standard C?
  2019-05-22 11:28 [Cocci] Does coccinelle support non-standard C? Christoph Böhmwalder
@ 2019-05-22 11:37 ` Julia Lawall
  2019-05-22 11:39   ` Christoph Böhmwalder
  0 siblings, 1 reply; 5+ messages in thread
From: Julia Lawall @ 2019-05-22 11:37 UTC (permalink / raw)
  To: Christoph Böhmwalder; +Cc: cocci

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On Wed, 22 May 2019, Christoph Böhmwalder wrote:

> Hi,
>
> Consider the following snippet of C:
>
>
> #define f() ({ puts("hello"); 0; })
> int main()
> {
>     printf("%d\n", f());
> }
>
>
> It uses an expression statement in the definition of `f`, which is a gcc
> extension.
>
> Now let's try to write a semantic patch to generate something like this:
>
>
> @@
> @@
> - cocci_replace_this()
> + ({ puts("hello"); 0; })
>
>
> With the C code as:
>
>
> #define f() cocci_replace_this()
> int main()
> {
>     printf("%d\n", f());
> }
>
>
> This prompts the following error message from spatch:
>
>
> $ spatch --sp-file test.cocci test.c
> init_defs_builtins: /usr/lib/coccinelle/standard.h
> 32 33
> Fatal error: exception Failure("plus: parse error: \n = File \"test.cocci\",
> line 4, column 3,  charpos = 32\n    around = '{', whole content = + ({
> puts(\"hello\"); 0; })\n")
>
>
> Now here's my question: this obviously implies that coccinelle doesn't support
> expression statements (or any other non-standard C for that matter).

The C parser should parse such statements.  I think it is indeed likely
that the semantic patch parser doesn't support them.  I wouldn't go as far
as saying that the semantic patch parser doesn't support any non-standard
C.  It pretty much supports what people have asked for, when there didn't
seem to be a workaround.

> Can I
> still somehow tell spatch to just replace it with this string of text instead
> of trying to parse it as C?

Is it always exactly this string that you want to add?

julia

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^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [Cocci] Does coccinelle support non-standard C?
  2019-05-22 11:37 ` Julia Lawall
@ 2019-05-22 11:39   ` Christoph Böhmwalder
  2019-05-22 11:55     ` Julia Lawall
  0 siblings, 1 reply; 5+ messages in thread
From: Christoph Böhmwalder @ 2019-05-22 11:39 UTC (permalink / raw)
  To: Julia Lawall; +Cc: cocci

On 22.05.19 13:37, Julia Lawall wrote:
> Is it always exactly this string that you want to add?

In my case, yes. I don't have any metavariable substitutions, etc; it's 
always the same constant code.

--
Regards,
Christoph

_______________________________________________
Cocci mailing list
Cocci@systeme.lip6.fr
https://systeme.lip6.fr/mailman/listinfo/cocci

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [Cocci] Does coccinelle support non-standard C?
  2019-05-22 11:39   ` Christoph Böhmwalder
@ 2019-05-22 11:55     ` Julia Lawall
  2019-05-22 11:57       ` Christoph Böhmwalder
  0 siblings, 1 reply; 5+ messages in thread
From: Julia Lawall @ 2019-05-22 11:55 UTC (permalink / raw)
  To: Christoph Böhmwalder; +Cc: cocci

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On Wed, 22 May 2019, Christoph Böhmwalder wrote:

> On 22.05.19 13:37, Julia Lawall wrote:
> > Is it always exactly this string that you want to add?
>
> In my case, yes. I don't have any metavariable substitutions, etc; it's always
> the same constant code.

You can do the following

@script:python b@
x;
@@

coccinelle.x = "({...})"    <--- The code you want

@@
identifier b.i;
@@
- cocci_replace_this()
+ i

julia

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https://systeme.lip6.fr/mailman/listinfo/cocci

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [Cocci] Does coccinelle support non-standard C?
  2019-05-22 11:55     ` Julia Lawall
@ 2019-05-22 11:57       ` Christoph Böhmwalder
  0 siblings, 0 replies; 5+ messages in thread
From: Christoph Böhmwalder @ 2019-05-22 11:57 UTC (permalink / raw)
  To: Julia Lawall; +Cc: cocci

On 22.05.19 13:55, Julia Lawall wrote:
> 
> 
> On Wed, 22 May 2019, Christoph Böhmwalder wrote:
> 
>> On 22.05.19 13:37, Julia Lawall wrote:
>>> Is it always exactly this string that you want to add?
>>
>> In my case, yes. I don't have any metavariable substitutions, etc; it's always
>> the same constant code.
> 
> You can do the following
> 
> @script:python b@
> x;
> @@
> 
> coccinelle.x = "({...})"    <--- The code you want
> 
> @@
> identifier b.i;
> @@
> - cocci_replace_this()
> + i
> 
> julia
> 

Cool, I guess that works. Thanks for the prompt reply and your help!

--
Regards,
Christoph
_______________________________________________
Cocci mailing list
Cocci@systeme.lip6.fr
https://systeme.lip6.fr/mailman/listinfo/cocci

^ permalink raw reply	[flat|nested] 5+ messages in thread

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Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-05-22 11:28 [Cocci] Does coccinelle support non-standard C? Christoph Böhmwalder
2019-05-22 11:37 ` Julia Lawall
2019-05-22 11:39   ` Christoph Böhmwalder
2019-05-22 11:55     ` Julia Lawall
2019-05-22 11:57       ` Christoph Böhmwalder

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