[cfe-dev] Modifying Structs

[mats petersson via cfe-dev]

On 15 January 2017 at 01:49, Anil Altinay <aaltinay at uci.edu> wrote:

> Hello Mats,
>
> I have a list of struct names and I need to change the order of fields of
> these structs. I think I can only do this in HandleTagDeclDefinition
> because once a struct definition is completed, it is called and the changes
> I do here will be applied to rest of the codegen.
>

Those structs have no name. There is a typedef-name, but the struct has no
name.

Maybe the trick is to not use a list of struct names, but identify the
relevant structures in some other way?

>
> I can access the name of the struct which is defined using typedef keyword
> in HandleTranslationUnit (ASTContext &Ctx) but it is going to be too late
> to make changes here. Please let me know if I think wrong.
>

It _may_ be too late. That depends on what you are actually trying to
achieve and how. If you are re-ordering fields, then yes, it'll involve
looking up all references to that field and changing it to the new index.
Compilers do more difficult things throughout compilation.


> Maybe there is a way to get the struct name in HandleTagDeclDefinition
> even if it is defined with typedef but I couldn't find it.
>

There is obviously a typedef name in the compiler, but it's not part of the
ASTConsumer interface to "give" that name (as far as I can see). I don't
know the answer to how you solve this.

--
Mats

>
> thanks,
> Anil
>
> On Sat, Jan 14, 2017 at 2:33 PM, mats petersson <mats at planetcatfish.com>
> wrote:
>
>> Why do you need to know its name? If you edit the actual object, it
>> should reflect everywhere it is referred to.
>>
>> --
>> Mats
>>
>> On 13 January 2017 at 21:47, Anil Altinay via cfe-dev <
>> cfe-dev at lists.llvm.org> wrote:
>>
>>> Actually, HandleTagDeclDefinition is called for Integer struct but I
>>> couldn't get the name of the struct which is "Integer" from TagDecl. Is
>>> there any way to do this in HandleTagDeclDefinition function.
>>>
>>> On Fri, Jan 13, 2017 at 12:22 AM, Anil Altinay <aaltinay at uci.edu> wrote:
>>>
>>>> Hello,
>>>>
>>>> I am writing an AST consumer to modify fields of the structs in a C
>>>> program and let clang to generate code accordingly. I was modifying
>>>> structs in HandleTagDeclDefinition(TagDecl *D) but I realized that if
>>>> a struct defined using typedef like below, HandleTagDeclDefinition is not
>>>> called after it's definition is completed. Is there any way to solve this
>>>> problem? Thank you.
>>>>
>>>> typedef struct
>>>> {
>>>>     int a;
>>>> } Integer;
>>>>
>>>> best,
>>>> Anil
>>>>
>>>
>>>
>>> _______________________________________________
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>>>
>>>
>>
>
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