Hello Julia,
thank you for helpful and fast response.
On 20.05.2015 23:58, Julia Lawall wrote:
>
>
> On Wed, 20 May 2015, Vladimir Zapolskiy wrote:
>
>> Hello Julia,
>>
>> please excuse me for a newbie question, I'm trying to find a way how to
>> match an assignment done from embracing struct or union.
>>
>> If you consider this C code sample:
>>
>> ----8<----
>> static void a(void) {};
>>
>> struct x {
>> void (*u)(void);
>> };
>>
>> struct y {
>> struct x v;
>> };
>>
>> struct x k = {
>> .u = a,
>> };
>>
>> struct y l = {
>> .v = {
>> .u = a,
>> },
>> };
>> ----8<----
>>
>> where "struct x" type is known and "struct y" may be arbitrary/unknown,
>> and I would like to match both assignments.
>>
>> My naïve rule finds only k.u assignment:
>>
>> ----8<----
>> @@
>> struct x X;
>> identifier value;
>> @@
>>
>> * X.u = value;
>> ----8<----
>>
>> I believe it should not be a problem for me to get access to ".u", if I
>> get ".v" identifier firstly, but here I encounter a problem, probably
>> because "{ .u = a, }" above is not considered as a valid expression to
>> be matched in a rule like ".f = E,".
>>
>> Any help is appreciated, thank you in advance.
>
> Could you live with the following?
>
> @@
> struct x X;
> identifier value;
> @@
>
> * X.u = value;
>
> @parent@
> identifier y,v;
> @@
>
> struct y {
> ...
> struct x v;
> ...
> };
>
> @@
> identifier l,parent.y,parent.v;
> struct y X;
Just to share my level of comprehension, I don't quite understand what
the line above is needed for.
> identifier value;
> @@
>
> struct y l = {
> .v = {
> * .u = value,
> },
> };
>
> -----------------------------------
>
> This will work for the case of a struct field inside a struct field, but
> not more levels of nesting.
Much better than nothing and I got the idea, thank you so much. It might
be a good improvement to coccinelle, if any level of nesting can be
technically supported (if it is not).
I ported the code to my actual project, and it works well, though spatch
1.0.0-rc24 produces a warning even on toy example above:
(ONCE) warning: struct/union with a metavariable name detected.
(ONCE) For type checking assuming the name of the metavariable is the
name of the type
> Do you expect the assignments to all be in structures, or sometimes
> in ordinary assignments? If you expect always structures, perhaps
> rewrite the first rule to mention structures. If there can be
> ordinary assignments, you can leave it as is.
Yes, my intention is to cover both cases, actually ordinary assignments
is the main case, but then I found that the discussed case is not
covered by my rule.
> But you may want to make a second copy without the ; if there is the
> possibility that such an assignment could be part of another
> expression, and thus without the ;. The ; though is necessary
> to get the isomorphism with structure field assignments.
>
In my particular situation it is unlikely, but I tested it and works as
expected.
Thank you for the great tool!
--
With best wishes,
Vladimir
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