Fetch children for TU from clangd

[ghentschke]

When expanding a translation unit in the CDT Project Explorer the IScannerInfo provides information about the functions and included files:

These information should not be provided by the CDT internal build AST for a project which prefers the LSP based C/C++ Editor. The language server should provide these informations.

[ghentschke]

The issue is here to determine how to get the AST from the LS and feed the cdt data model with the information from the LS AST.

Outcome could be an adapter between the ASt data and the cdt data model.

[ddscharfe]

• The AST can be fetched from the LS by providing a serverInterface in the org.eclipse.lsp4e.languageServer extension point. I already got this working and can provide the implementation for this
• To provide the cdt data model TranslationUnit::parseUsingCModelBuilder() needs to be changed to use a custom model builder. This could be also achieved by providing an own AbstractCLikeLanguage where createModelBuilder() creates the model builder.
• I think implementing the new model builder will be quiet some work, see CModelBuilder2 for reference

[ghentschke]

The idea now is to provide a new content provider for the project navigator view by extending the org.eclipse.ui.navigator.navigatorContent. The content provider can reuse the mechanism used by the outline view to determine the children of the translation unit. (see org.eclipse.lsp4e.outline.content)

[ddscharfe]

Sounds like a good approach which requires less effort than writing a new model builder.