[cfe-dev] Clang plugin reload AST with in memory changes

[Manuel Klimek via cfe-dev]

On Mon, Oct 5, 2015 at 6:05 PM Zsolt Parragi via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> Hello
>
> There was an email on this list about my question earlier in January:
>
> http://lists.llvm.org/pipermail/cfe-dev/2015-January/040760.html
>
> But it contained no specific information about how to do it, and I
> couldn't figure it out based on the docs.
>
> My problem is:
>
> I have a source-to-source transformation tool, built using
> AstMatchers/Rewriter. It's perfect when I want to compile something with
> gcc (I can transform the source with it, and run gcc on the modified
> source), and also works with clang, but I thought it could be integrated
> with it even better: a clang plugin, which rewrites the source, but instead
> of saving it to a file, clang just could reparse the modifications from the
> memory buffer and compile it...
>
> So I have a PluginASTAction, and a Rewriter member, containing everything
> I modified.
>
>  * I tried the solution used by tracer (link found in the same
> conversation), saving the modification to the DefaultOutputFile. That
> overwrites the original file on the disk, and doesn't reload it - the
> modification will be only visible during the next execution
>  * I also found ASTUnit::Reparse, which is accessible from any
> FrontendAction, but I only succeeded in causing segmentation faults with it
> - the function itself isn't used by clang itself, and I found no plugins /
> projects using it with google
>  * I could write a standalone program which transforms the source, saves
> it to a temporary file, runs clang with it, and deletes the temporary
> file... but I hope it can be solved in a better way.
>

You could use two ClangTools / ToolInvocations. You'll definitely need to
create a new instance, as you'll want a new SourceManager.
Generally, this is possible, but not really a common use case; most of the
time, people want to rewrite things in headers, where this approach quickly
leads to ODR violations


>
> (I read that the recommended way is just adding attributes to the AST and
> changing the IR, but that would require creating and maintaining two
> version of my tool)
>
> My questions:
>  * is this possible at all, with a plugin?
>  * If it is, the solution is Reparse and I'm just doing something wrong,
> or something entirely different?
>
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20151006/727e592c/attachment.html>