Access C preprocessor features from non-C vscode extension

[killerkalamari]

With the C/C++ extension installed, if I'm in a .c/.cpp/.h file and I hover over C uses of preprocessor macros (#defines), it will show a popup box where it shows "Expands to:". Additionally, if I right-click and choose "Go to Definition" or "Go to Declaration", it will navigate to that #define.

I've put together a rudimentary syntax highlighting plugin for a non-C assembler (xa65). The macros in xa65 are very similar to those of the C preprocessor (and it also supports direct use of the C preprocessor). It would be great to be able to somehow access the C preprocessor functionality of the C/C++ extension in order to support macro expanding and go to's in my extension as well.

I have a few questions:

1. Is my hope of using the preprocessor functionality of the C/C++ extension to support the above features even possible?
2. If so, is the functionality tied to C/C++ or will I be able to access the C preprocessor parts alone?
3. From an extension POV, what is the proper terminology for implementing "macro expanding" and "go to's"? And what is the terminology for using functionality from another extension in the manner above? I obviously have some reading and learning to do, and if possible I'd like to find my own answers.

[sean-mcmanus]

Our extension is only designed to work on C/C++ files...if you want the feature for non-C/C++ files you'd need to add the file or file extensions to the files.associations setting to associate it with "c" or "cpp", although in that case it might break some features with your extension.

Our extension is not designed to re-usable by extensions supporting other languages.

Our extension implements the LSP's hover (macro expanding) and definition requests: https://microsoft.github.io/language-server-protocol/specification#textDocument_hover and https://microsoft.github.io/language-server-protocol/specification#textDocument_definition (in our closed source cpptools process).

It's possible you might be able to register your extension as a C/C++ provider, but then don't register as providing hover/definition capabilities and it might fallback to using our extension...but I'm not familiar with what exactly happens when multiple providers for the same language are active.