[cfe-dev] questions regarding using addPPCallbacks

[Farzad Sadeghi via cfe-dev]

yes, InclusionDirective is implemented in PPInclusion.
ok, thank you.

On 12/8/16, Eric Liu <ioeric at google.com> wrote:
> You could do: CI.getPreprocessor().addCallbacks(...) instead. BTW, have you
> implemented InclusionDirective in PPInclusion?
>
> This is how clang-move handles it:
> https://github.com/llvm-mirror/clang-tools-extra/blob/master/clang-move/ClangMove.cpp#L401
>
> On Thu, Dec 8, 2016 at 12:51 AM Farzad Sadeghi via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
>> Lets say I want to add a PP callback every time the PP runs into an
>> InclusionDirective.
>> going through the docs, I find that clang::PPCallbacks has the virtual
>> member functions for me implement to do just that. So far so good.
>> Now, how to tell the PP to use my callbacks?
>> I came across addPPCallbacks in clang::Preprocessor.
>> The code already has a class that derives from ASTConsumer to add and
>> run the matchers.
>> There is also a class that derives from ASTFrontendAction that is
>> passed to newFrontendActionFactory to create an instance of, to be
>> passed to a ClangTool instance to run the action.
>> Now the questions:
>> Do i need to cerate a new FrontendAction for the PPCallbacks? If yes,
>> then does that mean that the inputs get lexed and parsed twice?
>>
>> There is only one preprocessor instance used for each
>> frontendaction,right?
>> So i need to get a hold of that instance and add my PPCallbacks there.
>> I went through the docs again and found that I could do that with a
>> clang::CompilerInstace.
>> Now in my class that derives from ASTFrontendAction, I figured I'm
>> getting the CompilerInstance, so maybe i can get the preprocessor
>> there:
>>   std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
>> StringRef file) override
>> {
>>     Preprocessor &PP = CI.getPreprocessor();
>>     PP.addCallbacks(std::unique_ptr<PPCallback> PPInclusion)
>>
>>     TheRewriter.setSourceMgr(CI.getSourceManager(), CI.getLangOpts());
>>     return llvm::make_unique<MyASTConsumer>(TheRewriter);
>>  }
>>
>> PPInclusio is the class that derives from clang::PPCallbacks.
>> But the compiler tells me "error: member access into incomplete type"
>> which basically means that the Preprocessor i got from
>> CompilerInstance is a forward declaration.
>> How can I actually add a preprocessor callback then?
>>
>>
>> --
>> Farzad Sadeghi
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>> cfe-dev mailing list
>> cfe-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
>


-- 
Farzad Sadeghi