[cfe-dev] Using libClang for parsing Source and Comments

[barbara via cfe-dev]

Milian,



> Hey Barbara,
>
> see answers inline below from my experience with the Clang C-API working on
> KDevelop.
>
> On Tuesday, February 23, 2016 10:23:52 AM CET barbara via cfe-dev wrote:
>> We have not found a tutorial or any documentation addressing our
>> requirement to use libClang for parsing C++ source and full comments.
>> We are currently using libClang 3.6 for testing however moving to 3.7 is
>> possible although we would rather wait for 3.8.
>>
>> At the present time we have code to walk the AST and obtain cursors and
>> tokens for a sample C++ header. The following are the initial problems
>> we have encountered.
>>
>> 1)    Locate C++ standard headers
>>
>> On Debian we did not have to pass any parameters to libClang for it to
>> locate the C++ standard header files.
>>
>> On Windows, I had to pass six include lines which referenced GCC std
>> header files. This works but it will be cumbersome for our users. We
>> talked with a few people at the last llvm meeting  it was mentioned
>> there might be some enhancements for detecting the system headers.
>>
>> Do anyone have ideas or suggestion about this?
> I think this is still unresolved, but would be glad to be told otherwise.

I am hoping someone with knowledge in this area can shed some light on 
this problem.



>
>> 2)    We need to retrieve all the comments and using "cursors" this has
>> not worked.  We can easily generate a list of the tokens and walking
>> these appear to show the comments, however this feels very awkward and
>> slow.  We understand the basic idea of cursors and tokens. We are not
>> sure about the pros and cons of each approach.
> We also iterate over the tokens in KDevelop to find comments not associated
> with a  cursor, such as
>
> ///FIXME this is broken
> /**
>   * doxygen comment
>   */
> void foo();
>
> If you only need access to the comments of cursors, i.e. the second comment
> above, you should be fine with clang_Cursor_getParsedComment and without
> tokens.

It does seem like using the tokens is the appropriate way to handle 
parsing comments.  Just wanted to make sure we were not missing 
something obvious.



>
>> 3)  Is the -Wdocumentation flag passed to clang when building. Or is
>> this flag supposed to be passed to libClang?  Will this provide us with
>> more of the user comments?  It appeared to to have no effect.
> You need to pass that as part of the argv to clang_parseTranslationUnit2.
>

We are using clang_parseTranslationUnit2 and the flag did not have any 
effect.  Is there a chance this was not supported in 3.6?


Thanks for your input.


Barbara



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