[cfe-dev] clang AST printer

[Manuel Klimek]

On Fri, Sep 21, 2012 at 5:40 PM, Dmitri Gribenko <gribozavr at gmail.com> wrote:
> On Fri, Sep 21, 2012 at 6:37 PM, Manuel Klimek <klimek at google.com> wrote:
>> On Fri, Sep 21, 2012 at 5:32 PM, Dmitri Gribenko <gribozavr at gmail.com> wrote:
>>> On Fri, Sep 21, 2012 at 4:21 PM, Alexander Kornienko <alexfh at google.com> wrote:
>>>>
>>>> On Fri, Sep 21, 2012 at 2:40 PM, Manuel Klimek <klimek at google.com> wrote:
>>>>>
>>>>> On Fri, Sep 21, 2012 at 12:32 PM, Philip Craig <philipjcraig at gmail.com>
>>>>> wrote:
>>>>> > On Fri, Sep 21, 2012 at 7:49 PM, Manuel Klimek <klimek at google.com>
>>>>> > wrote:
>>>>> >> Hi Philip,
>>>>> >>
>>>>> >> we had a discussion around the strategy for handling ast dumping
>>>>> >> fairly recently. I think the common agreement in the end was that
>>>>> >> instead of having an extra tool, we want to make clang's -ast-dump
>>>>> >> awesome.
>>>>> >
>>>>> > Was this discussion on the mailing list? Any chance you could point me
>>>>> > to it?
>>>>>
>>>>>
>>>>> http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20120716/060831.html
>>>>>
>>>>> >> I don't know what your ultimate goal is here, but from my
>>>>> >> side any work that goes towards making clang -ast-dump better would be
>>>>> >> highly appreciated :)
>>>>> >
>>>>> > My motivation was having some way of getting the structure of the AST
>>>>> > for a given piece of source code, so that it is easier to correctly
>>>>> > call the AST matchers to match that code. The issue with clang
>>>>> > -ast-dump is that it pretty prints decls and types. So would the goal
>>>>> > here be to add more command line options to clang to control how
>>>>> > -ast-dump prints the AST?
>>>>>
>>>>> No, I think the goal is to dump decls and types in a sensible way :)
>>>>
>>>>
>>>> More specifically, I think we agreed on changing -ast-dump from
>>>> pretty-printing declarations to outputting them in the same LISP-style
>>>> format, which is used for statements. I was going to implement that, but
>>>> never had time to do this. If you're going to continue work on your utility,
>>>> it would be much more valuable, if you instead improved clang's current
>>>> -ast-dump option. In that case you consider to go this way, here's where to
>>>> start:
>>>>
>>>> clang/lib/Frontend/ASTConsumers.cpp:120: ASTConsumer
>>>> *clang::CreateASTDumper(StringRef FilterString)
>>>>
>>>> is a common entry point, used by "clang -cc1 -ast-dump" and by "clang-check
>>>> -ast-dump". An additional benefit from this would be that after "-ast-dump"
>>>> starts outputting the AST for declarations in a structured form,
>>>> "-ast-dump-xml" will become useless and can be removed.
>>>
>>> Does this mean that current declaration printer will be removed?  I
>>> see value in having a decl printer that prints declarations in
>>> user-readable form, so I think we should keep it until clang-format
>>> will be here.
>>
>> I'd be curious what your use case is - after all, it'll only print
>> declrations in user-readable form, and all the other stuff will be
>> written in S-epxression-like syntax.
>
> The decl printer could be used to pretty-print decls in some
> clang-based documentation generation system.
>
>> If we want a pretty-printer, I'd expect -pretty-print and not
>> -ast-dump to trigger that?
>
> I'd just leave it as an API.

I'm not sure what you mean by that. I agree that there are use cases
for a pretty printer, but I think "half" of the ast-dump mechanism is
a bad place to have a pretty printer...

Cheers,
/Manuel

>
> Dmitri
>
> --
> main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
> (j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at gmail.com>*/