Those are probably caused by an issue in your project setup, but I don't think that this is the right place to go into details. If you like to investigate, please send us an e-mail!
A Compile Command is a JSON file entry that specifies what the C/C++ compiler should do when compiling a file. So it defines a file to compile and all the required flags (like include paths or preprocessor defines). These Compile Commands are used for all kind of Clang based tools. You can read more here: https://clang.llvm.org/docs/JSONCompilationDatabase.html
Yes, Sourcetrail also shows class internal calls and accessed fields. Code Maps in VS has a different approach because they try to keep the graph small by making the user add symbols. So if you are trying to see every access of a symbol it is easy to miss something. Sourcetrail on the other hand keeps the graph small and comprehensible by showing only one level of dependencies. You don't need to add anything yourself. So you cannot miss any relation ;)
Unfortunately it doesn't. Even though Scala and Java output the same kind of bytecode, these languages have different language specifications. We currently only support what's in the JLS.
Happy to hear that you like it! Full support of Python won't be easy but maybe we could tackle this one in stages. Implement highly demanded features in a first Python release and improve on that later on.
To be honest: We have not decided what language we will pick up next. Our first priority is to improve on our Java coverage. In a few months we should be ready to choose our next language. We are thinking about either tackling Python or implement support for a more recent language like Kotlin, Swift or Go.
We have been working on that for the past few month. Right now the performance is pretty good for C++ projects up to around 2 million lines of code. For C projects the performance is even better! If you want to test it, just download the pre-indexed clang project (900k loc) from our website (https://www.sourcetrail.com/downloads#extra). Indexing the project took 12 minutes on a 5 year old laptop.
Kotlin is definitely on the shortlist for the next language to be supported! Which language we'll pick up exactly depends on the landscape of available tools for that language. Kotlin is pretty new so I guess that there could be a need for Sourcetrail :)
Some time ago I met the people behind SmartGit (a cross platform git client) and they told me that using Google groups worked quite well for this purpose.