[cfe-dev] Source information for types

[Enea Zaffanella]

Argyrios Kyrtzidis wrote:
> Hi Enea,
> 
> On Aug 8, 2009, at 1:11 AM, Enea Zaffanella wrote:
> 
>> Hello.
>>
>> Argyrios Kyrtzidis wrote:
>>> Hi clang community,
>>> I'd like to make a proposal for keeping source location information  
>>> for types in the AST, to allow functionality like "find the source  
>>> locations where this typedef is used".
>> [...snip...]
>>> TypeSpecifier will replace the QualType fields in the Decls. For  
>>> example, ValueDecl will contain a TypeSpecifier instead of a plain  
>>> QualType.
>>> "QualType ValueDecl::getType()" will delegate to 
>>> TypeSpecifier::getType () (ValueDecl::getType() will still return a 
>>> QualType).
>>> TypeSpecifier will also be contained in Exprs that deal with type- 
>>> specifiers, like SizeOfAlignOfExpr.
>> [...]
>>
>> As clang users, we would be really interested in such a proposal (or a 
>> functionally equivalent one) and hence we would like to know if there 
>> have been progresses ... or there are plans in this respect.
> 
> Yes, I quite recently started working on this feature.

This is really good news!

[...]
>> Another issue that could be solved by following this proposal is the 
>> ability to distinguish different syntactic representations of the same 
>> type; namely, distinguishing "unsigned" from "unsigned int" from "int 
>> unsigned" and the like.
> 
> What are the use cases for this, do you also need it to check adherence 
> to coding standards ?

Yes. (In this particular case, I suspect that coding standard checkers 
are the only application.)

>>
>> As yet another example, we would like to be able to distinguish between
>>  void (*pf)(int left_is_array[], int* right_is_pointer);
>> vs
>>  void (*pf)(int* left_is_pointer, int right_is_array[]);
>>
>> [Note: since pf is a pointer to function, there are no parameters, 
>> hence we cannot keep track of the parameter names nor we can retrieve 
>> the original type from OriginalParmVarDecl].
>>
>> In our opinion, re-lexing the type specifier is not an option.
> 
> We will definitely handle this. The way I see it, you'll be able to get 
> at the parameters through the type source info (and look into the 
> parameter's type info too).
> 
> -Argiris
> 

Well, many many thanks in advance.

Cheers,
Enea.