[PATCH] D153114: [clangd] [C++20] [Modules] Support C++20 modules for clangd

[Sam McCall via Phabricator via cfe-commits]

sammccall added a comment.

(Sorry, hit send too soon)

I suspect the answer for header modules is that we can study this patch and understand what the equivalents of graph nodes/deps/names/scanning look like for explicit header modules, and understand that we'll be able to abstractify some names and add some levels of indirection and it'll all work out.

For large project support, I suspect a bit more thought is needed.
We'll need some abstraction layer (like CompilationDatabase is to compile_commands.json) that exposes enough data to run the algorithms we need, without exposing so much that you have to hold the whole graph in memory. It could be backed by in-memory depscan results, or a build-system artifact, or a live query of the build system.
For "every time we update a file, all the affected files (e.g., we changed a header file) will be re-scanned" - we need a way to express this more abstractly than "re-scanned", and more narrowly than "all the affected files" - at least it needs to be limited to all the files that could themselves affect any open file.

(Going to dig into the design now and come back with more thoughts)


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  https://reviews.llvm.org/D153114/new/

https://reviews.llvm.org/D153114