CodeQL cannot resolve some classes and methods

[ArtiomKr]

I just started using CodeQL and faced with the problem that the extension does not see some classes. What could be the problem?

CodeQL extension version: 1.17.1
CodeQL CLI version: 2.20.0
Platform: linux x64

[intrigus-lgtm]

There is an old interface for the data flow library and a new one.
The old interface has been deprecated last December I believe.

See here for information on how to convert from the old version to the new one:
https://github.blog/changelog/2023-08-14-new-dataflow-api-for-writing-custom-codeql-queries/

[ArtiomKr]

Thanks, you were right. However, after copying the example, I came across new errors, which, as I understand it, should not be. Could it have something to do with some additional import?

And is it possible to use the old API? Which versions of CodeQL extension and CodeQL CLI are needed for this?

[redsun82]

👋 @ArtiomKr

The example in the blog post was meant to showcase the changes in the dataflow API (the part where we need to implement DataFlow::ConfigSig, with its predicates isSource and isSink). The actual implementation of those predicates still needs to use the specific language API, which is different from language to language. The example in the blog post was done with Java, so it is expected that copying that example with an import cpp won't compile.

In your case you need to use the C/C++ library. You can probably just copy and paste the isSource and isSink bodies you posted in your initial question as the bodies of the same predicates in a module block implementing DataFlow::ConfigSig.

Here's some further documentation that you might find useful:

• Data flow in C/C++
• C/C++ library