[cfe-dev] clang AST printer

Manuel Klimek klimek at google.com
Fri Sep 21 08:37:43 PDT 2012

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.

If we want a pretty-printer, I'd expect -pretty-print and not
-ast-dump to trigger that?


> BTW, a while ago I added tests for current decl printer to
> unittests/AST/DeclPrinterTest.cpp.
> 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>*/
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