[cfe-dev] Distinguish between array parameters and pointer parameters in the AST.

[Alexei Svitkine]

You could get the original source range and look at it that way...

-Alexei

On Fri, Feb 20, 2009 at 12:22 PM, Roberto Bagnara <bagnara at cs.unipr.it> wrote:
> steve naroff wrote:
>>
>> On Feb 20, 2009, at 11:26 AM, Paolo Bolzoni wrote:
>>
>>> dear cfe list,
>>>
>>> According to the clang AST the two parameters' type of this function
>>> declaration are the same:
>>>
>>> int f(int a[], int* b);
>>>
>>> while it makes sense, I'd like to distinguish.
>>> Is it not possible?
>>>
>>
>> Not currently. Here is a comment from Sema::Sema::ActOnParamDeclarator():
>>
>>   // Perform the default function/array conversion (C99 6.7.5.3p[7,8]).
>>   // Doing the promotion here has a win and a loss. The win is the type for
>>   // both Decl's and DeclRefExpr's will match (a convenient invariant
>> for the
>>   // code generator). The loss is the orginal type isn't preserved. For
>> example:
>>   //
>>   // void func(int parmvardecl[5]) { // convert "int [5]" to "int *"
>>   //    int blockvardecl[5];
>>   //    sizeof(parmvardecl);  // size == 4
>>   //    sizeof(blockvardecl); // size == 20
>>   // }
>>   //
>>   // For expressions, all implicit conversions are captured using the
>>   // ImplicitCastExpr AST node (we have no such mechanism for Decl's).
>>   //
>>   // FIXME: If a source translation tool needs to see the original type,
>> then
>>   // we need to consider storing both types (in ParmVarDecl)...
>>   //
>>
>> HTH,
>
> Thanks Steve.  In our case we need to see the original type: there are
> coding rules that we need to check where the distincion is crucial.
> For instance:
>
> int f(int a[], int* b) {
>    a[0] = 0;     /* Compliant. */
>    b[5] = 0;     /* Not Compliant: as b was not declared as an array,
>                                    MISRA rule 17.4 is violated.  */
> }
>
> How difficult would be to address the FIXME above?
> Best,
>
>    Roberto
>
> --
> Prof. Roberto Bagnara
> Computer Science Group
> Department of Mathematics, University of Parma, Italy
> http://www.cs.unipr.it/~bagnara/
> mailto:bagnara at cs.unipr.it
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