[Cocci] Problem writing simple patch

[Cocci] Problem writing simple patch

[David Frey]

Hi,

I'm trying to write a .cocci file to transform all calls to a function
"f(ex)" to something like this:

#ifdef USE_F
f(ex)
#else
g(ex)
#endif

The function has this signature:
bool f(int x);

This is the patch that I tried to use:
@@
expression ex;
@@
+#ifdef USE_F
 f(ex)
+#else
+g(ex)
+#endif


This is the result of running it:
$ spatch --show-c --sp-file test.cocci test.c
init_defs_builtins: /usr/bin/../lib/coccinelle/standard.h
plus: parse error:
  File "test.cocci", line 7, column 1, charpos = 50
  around = 'g',
  whole content = +g(ex)

What is wrong with the patch above?

Thanks,
David
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Re: [Cocci] Problem writing simple patch

[Julia Lawall]

On Mon, 25 Nov 2019, David Frey wrote:

> Hi,
>
> I'm trying to write a .cocci file to transform all calls to a function
> "f(ex)" to something like this:
>
> #ifdef USE_F
> f(ex)
> #else
> g(ex)
> #endif
>
> The function has this signature:
> bool f(int x);
>
> This is the patch that I tried to use:
> @@
> expression ex;
> @@
> +#ifdef USE_F
>  f(ex)
> +#else
> +g(ex)
> +#endif
>
>
> This is the result of running it:
> $ spatch --show-c --sp-file test.cocci test.c
> init_defs_builtins: /usr/bin/../lib/coccinelle/standard.h
> plus: parse error:
>   File "test.cocci", line 7, column 1, charpos = 50
>   around = 'g',
>   whole content = +g(ex)
>
> What is wrong with the patch above?

Coccinelle doesn't currently support adding ifdefs on expressions, only on
statements.

You could try for some typical usage contexts, like

+ifdef...
x = f(ex);
+#else
+x = g(ex);
+#endif

julia
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Re: [Cocci] Specifying conditional compilation with SmPL

[Markus Elfring]

> Coccinelle doesn't currently support adding ifdefs on expressions,
> only on statements.

Can the following transformation approach ever work

@adjustment2@
expression x;
@@
+#ifdef USE_F
 f
+#else
+g
+#endif
 (x);

in addition to this code variant for the semantic patch language?

@adjustment1@
expression x;
@@
+#ifdef USE_F
 f(x);
+#else
+g(x);
+#endif


Regards,
Markus
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Re: [Cocci] Specifying conditional compilation with SmPL

[Julia Lawall]

--- Please note the new email address ---


On Tue, 26 Nov 2019, Markus Elfring wrote:

> > Coccinelle doesn't currently support adding ifdefs on expressions,
> > only on statements.
>
> Can the following transformation approach ever work
>
> @adjustment2@
> expression x;
> @@
> +#ifdef USE_F
>  f
> +#else
> +g
> +#endif
>  (x);

Obviously, it what was asked for would work, this would work too.  We're
not going to make a special case to exclude expressions that are
identifiers.  But the generated code would look horrible.

The reason for putting an ifdef on an expression would be that the
expression could appear in other contexts, such as conditional tests, not
to minimize the number of characters in the file.

julia

>
> in addition to this code variant for the semantic patch language?
>
> @adjustment1@
> expression x;
> @@
> +#ifdef USE_F
>  f(x);
> +#else
> +g(x);
> +#endif
>
>
> Regards,
> Markus
>
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Re: [Cocci] Problem writing simple patch

[David Frey]

On 11/25/2019 1:10 PM, Julia Lawall wrote:
> On Mon, 25 Nov 2019, David Frey wrote:
> 
>> Hi,
>>
>> I'm trying to write a .cocci file to transform all calls to a function
>> "f(ex)" to something like this:
>>
>> #ifdef USE_F
>> f(ex)
>> #else
>> g(ex)
>> #endif
>>
>> The function has this signature:
>> bool f(int x);
>>
>> This is the patch that I tried to use:
>> @@
>> expression ex;
>> @@
>> +#ifdef USE_F
>>  f(ex)
>> +#else
>> +g(ex)
>> +#endif
>>
>>
>> This is the result of running it:
>> $ spatch --show-c --sp-file test.cocci test.c
>> init_defs_builtins: /usr/bin/../lib/coccinelle/standard.h
>> plus: parse error:
>>   File "test.cocci", line 7, column 1, charpos = 50
>>   around = 'g',
>>   whole content = +g(ex)
>>
>> What is wrong with the patch above?
> 
> Coccinelle doesn't currently support adding ifdefs on expressions, only on
> statements.
> 
> You could try for some typical usage contexts, like
> 
> +ifdef...
> x = f(ex);
> +#else
> +x = g(ex);
> +#endif
> 
> julia
> 


Hi Julia,

Thanks for your explanation and your suggestion.  I ended up creating a
new header that was like this:

#ifdef SOMETHING
#define foo_backport_x(_arg) bar_x(_arg)
#define foo_backport_y(_arg) bar_y(_arg)
#else
#define foo_backport_x(_arg) foo_x(_arg)
#define foo_backport_y(_arg) foo_y(_arg)
#endif

and then I defined coccinelle rules to change:
foo_x -> foo_backport_x
foo_y -> foo_backport_y

It's not the most elegant solution, but it works.

David
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Re: [Cocci] Problem writing simple patch

[Julia Lawall]

--- Please note the new email address ---


On Tue, 26 Nov 2019, David Frey wrote:

> On 11/25/2019 1:10 PM, Julia Lawall wrote:
> > On Mon, 25 Nov 2019, David Frey wrote:
> >
> >> Hi,
> >>
> >> I'm trying to write a .cocci file to transform all calls to a function
> >> "f(ex)" to something like this:
> >>
> >> #ifdef USE_F
> >> f(ex)
> >> #else
> >> g(ex)
> >> #endif
> >>
> >> The function has this signature:
> >> bool f(int x);
> >>
> >> This is the patch that I tried to use:
> >> @@
> >> expression ex;
> >> @@
> >> +#ifdef USE_F
> >>  f(ex)
> >> +#else
> >> +g(ex)
> >> +#endif
> >>
> >>
> >> This is the result of running it:
> >> $ spatch --show-c --sp-file test.cocci test.c
> >> init_defs_builtins: /usr/bin/../lib/coccinelle/standard.h
> >> plus: parse error:
> >>   File "test.cocci", line 7, column 1, charpos = 50
> >>   around = 'g',
> >>   whole content = +g(ex)
> >>
> >> What is wrong with the patch above?
> >
> > Coccinelle doesn't currently support adding ifdefs on expressions, only on
> > statements.
> >
> > You could try for some typical usage contexts, like
> >
> > +ifdef...
> > x = f(ex);
> > +#else
> > +x = g(ex);
> > +#endif
> >
> > julia
> >
>
>
> Hi Julia,
>
> Thanks for your explanation and your suggestion.  I ended up creating a
> new header that was like this:
>
> #ifdef SOMETHING
> #define foo_backport_x(_arg) bar_x(_arg)
> #define foo_backport_y(_arg) bar_y(_arg)
> #else
> #define foo_backport_x(_arg) foo_x(_arg)
> #define foo_backport_y(_arg) foo_y(_arg)
> #endif
>
> and then I defined coccinelle rules to change:
> foo_x -> foo_backport_x
> foo_y -> foo_backport_y
>
> It's not the most elegant solution, but it works.

Persoally, I would find lots of ifdefs around expressions in the code
rather ugly too, so I'm not sure that it is such a bad solution, although
the name is not pretty...

julia
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