[cfe-dev] facebook clang plugins

[Sean Silva]

I'd just like to say that even if OCaml tools parsing JSON is out of scope
as Nico suggests, the work you have done to "schematize" the Clang AST
could be the start of something really useful for upstream. Currently, I
can think of at least two places that would benefit greatly from having
such a schema as a "single point of truth": Serialization and ASTMatchers.

Being able to auto-generate those two from a schema (maybe in the form of
annotations in the header files) plus a relatively small amount of
generator code could eliminate thousands of lines of code.

If RecursiveASTVisitor (~2500 lines) and TreeTransform (~10k lines) could
also be generated from the "single point of truth" with relatively little
code, then that would be a tremendous savings.

I think your OCaml tool would be quite easy to write with Clang annotated
as such, but you could let the Clang developers maintain the annotations
for you ;)

This might also pave the way for a more "data-driven" approach to the
DynamicASTMatchers, which could significantly reduce the binary size (which
is enormous, and IIRC is mostly due to the fact that is just
pre-instantiates all the static templates). The same approach might work
for the "static" ASTMatchers too, letting the compiler essentially
constant-fold all the indirections (which will largely be member pointers I
imagine). This might also improve compile time (which is an issue; see
http://llvm.org/bugs/show_bug.cgi?id=20061).

-- Sean Silva


On Thu, Jun 19, 2014 at 10:30 AM, Mathieu Baudet <mathieubaudet at fb.com>
wrote:

> Hi,
>
> I am looking for feedback on the possibility of contributing some of the
> clang plugins used at Facebook back to clang.
>
> We just made available a first subset of plugins here:
> https://github.com/facebook/facebook-clang-plugins
>
> The plugins fall into two groups:
> 1) Clang analyzer checkers for iOS;
> 2) A clang frontend plugin to export the internal AST of clang in an
> Ocaml-friendly Json. This plugin comes with Ocaml libraries for testing,
> parsing, and visiting the AST.
>
> Except for the naming conventions, which are not uniform yet, and the need
> to update the referenced version of clang, the code should be in a
> relatively good state. In particular, everything has been tested quite at
> scale.
>
> Thanks!
> —
> Mathieu Baudet
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>
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