[Cocci] How to concatenate identifier with text?

[Cocci] How to concatenate identifier with text?

[Timur Tabi]

@@
identifier func;
@@
func(...) {
<+...
     .... stuff
+   goto func_exit;
+}
...+>
}

So if I have this code:

void myfunc(int x)
{
}

I want it to look like this:

void myfunc(int x)
{
    goto myfunc_exit;
}

My problem is that cocci takes "func_exit" literally.  I tried
func##_exit, but that didn't work.  How do I make this work?
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Re: [Cocci] How to concatenate identifier with text?

[Timur Tabi]

On Fri, May 24, 2019 at 2:13 PM Timur Tabi <timur@kernel.org> wrote:

> void myfunc(int x)
> {
>     goto myfunc_exit;
> }
>
> My problem is that cocci takes "func_exit" literally.  I tried
> func##_exit, but that didn't work.  How do I make this work?

I figured it out:

@@
identifier func;
fresh identifier label = func ## "_exit";
@@
func(...) {
<+...
+    goto label;
...+>
}
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Re: [Cocci] How to concatenate identifier with text?

[Julia Lawall]

On Fri, 24 May 2019, Timur Tabi wrote:

> @@
> identifier func;
> @@
> func(...) {
> <+...
>      .... stuff
> +   goto func_exit;
> +}
> ...+>
> }
>
> So if I have this code:
>
> void myfunc(int x)
> {
> }
>
> I want it to look like this:
>
> void myfunc(int x)
> {
>     goto myfunc_exit;
> }
>
> My problem is that cocci takes "func_exit" literally.  I tried
> func##_exit, but that didn't work.  How do I make this work?

Python.  You need one rule to collect the func name, then a python rule to
create the new identifier you want, and then a third rule to do the
transformation.  See coccinelle/demos/pythontococci.cocci

julia
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Re: [Cocci] How to concatenate identifier with text?

[Julia Lawall]

On Fri, 24 May 2019, Timur Tabi wrote:

> On Fri, May 24, 2019 at 2:13 PM Timur Tabi <timur@kernel.org> wrote:
>
> > void myfunc(int x)
> > {
> >     goto myfunc_exit;
> > }
> >
> > My problem is that cocci takes "func_exit" literally.  I tried
> > func##_exit, but that didn't work.  How do I make this work?
>
> I figured it out:
>
> @@
> identifier func;
> fresh identifier label = func ## "_exit";

Yes, that works too.  Simpler than my suggestion.

julia

> @@
> func(...) {
> <+...
> +    goto label;
> ...+>
> }
> _______________________________________________
> Cocci mailing list
> Cocci@systeme.lip6.fr
> https://systeme.lip6.fr/mailman/listinfo/cocci
>
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Re: [Cocci] How to concatenate identifier with text?

[Timur Tabi]

On Fri, May 24, 2019 at 2:38 PM Julia Lawall <julia.lawall@lip6.fr> wrote:
> On Fri, 24 May 2019, Timur Tabi wrote:
> > I figured it out:
> >
> > @@
> > identifier func;
> > fresh identifier label = func ## "_exit";
>
> Yes, that works too.  Simpler than my suggestion.

I managed to break it somehow.  I suspect I ran into some other quirk
of coccinelle.  I'm trying to convert that looks like this:

x = MACRO1(stuff);
if (x == NULL)
{
  BREAKPOINT();
  status = ERROR;
  goto myfunc_exit;
}

into:
x = MACRO1(stuff);
CHECK_OR_BP_AND_GOTO(x == NULL, status, ERROR, _exit);

I thought this would work:

@@
type T;
expression y, z;
identifier x, s;
identifier func;
fresh identifier label = func ## "_exit";
@@
func(...) {
<+...
 x =
 (T)
 \(MACRO1\|MACRO2\)
 (...);
-if (y)
-{
-      BREAKPOINT();
-      s = z;
-      goto label;
-}
+CHECK_OR_BP_AND_GOTO(y, s, z, _exit);
...
 label:
...+>
}

but I get this error:

18: unexpected use of a fresh identifier label

What am I missing?
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Re: [Cocci] How to concatenate identifier with text?

[Timur Tabi]

On Tue, Jun 11, 2019 at 4:51 PM Timur Tabi <timur@kernel.org> wrote:
> but I get this error:
>
> 18: unexpected use of a fresh identifier label
>
> What am I missing?

Apparently I'm missing this obscure line in the documentation:

"Fresh identifier metavariables must only be used in + code."

Any suggestions on how to work around this, other than use Python?
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Re: [Cocci] How to concatenate identifier with text?

[Julia Lawall]

On Tue, 11 Jun 2019, Timur Tabi wrote:

> On Fri, May 24, 2019 at 2:38 PM Julia Lawall <julia.lawall@lip6.fr> wrote:
> > On Fri, 24 May 2019, Timur Tabi wrote:
> > > I figured it out:
> > >
> > > @@
> > > identifier func;
> > > fresh identifier label = func ## "_exit";
> >
> > Yes, that works too.  Simpler than my suggestion.
>
> I managed to break it somehow.  I suspect I ran into some other quirk
> of coccinelle.  I'm trying to convert that looks like this:
>
> x = MACRO1(stuff);
> if (x == NULL)
> {
>   BREAKPOINT();
>   status = ERROR;
>   goto myfunc_exit;
> }
>
> into:
> x = MACRO1(stuff);
> CHECK_OR_BP_AND_GOTO(x == NULL, status, ERROR, _exit);
>
> I thought this would work:
>
> @@
> type T;
> expression y, z;
> identifier x, s;
> identifier func;
> fresh identifier label = func ## "_exit";
> @@
> func(...) {
> <+...
>  x =
>  (T)
>  \(MACRO1\|MACRO2\)
>  (...);
> -if (y)
> -{
> -      BREAKPOINT();
> -      s = z;
> -      goto label;
> -}
> +CHECK_OR_BP_AND_GOTO(y, s, z, _exit);
> ...
>  label:
> ...+>
> }
>
> but I get this error:
>
> 18: unexpected use of a fresh identifier label
>
> What am I missing?

Fresh identifiers are only for + code.

You need to construct the identifier you want to match using python code,
as illustrated in demos/pythontococci.cocci

julia
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Re: [Cocci] Wider usage of “fresh identifiers”?

[Markus Elfring]

> Apparently I'm missing this obscure line in the documentation:
>
> "Fresh identifier metavariables must only be used in + code."
>
> Any suggestions on how to work around this, other than use Python?

Would you get into the mood to adjust this software situation any more?
(Increase OCaml development?)

How do you think about to check the mentioned restriction in more detail?

Regards,
Markus
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