Re: [cocci] Adjusting attributes for variables with SmPL?

On Wed, 27 May 2026, Pierrick Philippe wrote:

> On 5/27/26 11:16, Julia Lawall wrote:
> > On Wed, 27 May 2026, Pierrick Philippe wrote:
> >> On 5/27/26 10:59, Julia Lawall wrote:
> >>> On Wed, 27 May 2026, Pierrick Philippe wrote:
> >>> I think that the problem is that { ... } is not actually an expression in
> >>> C.  It's a strange thing that can only exist as part of a declaration.
> >>>
> >>> But you don't want to change it, so you don't need a metavariable for it.
> >>>
> >>> Just write:
> >>>
> >>> - T F =
> >>> + T __attribute__((myattr(("X")))) F =
> >>>   { ... };
> >> It does work indeed, thanks a lot!
> >> Although the metavariable X is not interpreted in the `+` context, could
> >> it be due to the attribute or unrelated?
> > It's due to the string quotes.
> >
> > It nmight be possible to get around this with a fresh identifier:
> >
> > fresh identifier x = "\"" # X # "\"";
>
> So this work, although the output still have the escaped quote, probably
> due to the same "issue" regarding quote.

I'm sorry, but I don't know what you want for the output.  Could you
provide an example?  If you don't want quotes at all, then you don't need
quotes at all.

julia

>
> But there also is a possible issue with the parsing/code generation
> here, generated diff and output of spatch:
>
> ```
> @attribute_struct_scalar_type_resolve@
> expression E1, E2;
> type T;
> identifier F, X;
> fresh identifier param = "\"" ## X ## "\"";
> @@
> T 
> +__attribute__((myattr((param))))
> F = { ... };
> ...
> memcmp(&F.X, E1, E2)
>
> warning: attribute_struct_scalar_type_resolve: metavariable param not
> used in the + code
> HANDLING: ./test.c
> -----------------------------------------------------------------------
> let's go
> -----------------------------------------------------------------------
> -----------------------------------------------------------------------
> -----------------------------------------------------------------------
> attribute_struct_scalar_type_resolve = 
> -----------------------------------------------------------------------
> dependencies for rule attribute_struct_scalar_type_resolve satisfied:
> binding in = []
> binding relevant in = []
>      transformation info returned:
>           transform state: 7
>                with rule_elem: T
>                                  >>> __attribute__ ((myattr((param))))
>                                        F = {...
>                                             ,
>                                             };
>                with binding: [attribute_struct_scalar_type_resolve.param
> --> id \"x\";
>                              attribute_struct_scalar_type_resolve.X -->
> id x]
>      binding out = []
>      transform one node: 7
> parse error 
>  = error in /tmp/cocci_small_output-112399-acda44-test.c; set
> verbose_parsing for more info
> badcount: 2
> bad: 
> bad: 
> bad: int main(void) {
> -----------------------------------------------------------------------
> Finished
> -----------------------------------------------------------------------
> parse error 
>  = error in /tmp/cocci-output-112399-6b7713-test.c; set verbose_parsing
> for more info
> badcount: 3
> bad: };
> bad: 
> bad: int main(void) {
> BAD:!!!!!     struct foo __attribute__((myattr((\"x\")))) f = { 42, 42 };
> diff = 
> --- ./test.c
> +++ /tmp/cocci-output-112399-6b7713-test.c
> @@ -6,9 +6,9 @@ struct foo {
>  };
>  
>  int main(void) {
> -    struct foo f = { 42, 42 };
> +    struct foo __attribute__((myattr((\"x\")))) f = { 42, 42 };
>      int b;
>      int *c = &b;
>      int z = memcmp(&f.x, c, sizeof(int));
>      return z;
> -}
> +}"
> Check duplication for 1 files
> ```
>
> It seems like a quote is added at the end of the main function itself.
>
> > I haven't tried this, though.  Another more complex solution involves
> > passing through python code.  You can get inspiration from
> > demos/pythontococci.cocci.  You would want to set eg coccinelle.z to a
> > string that additionally contains the desired string quotes.
> >
> > julia
>