Version: 1.84.2 (user setup)
Commit: 1a5daa3
Date: 2023-11-09T10:51:52.184Z
Electron: 25.9.2
ElectronBuildId: 24603566
Chromium: 114.0.5735.289
Node.js: 18.15.0
V8: 11.4.183.29-electron.0
OS: Windows_NT x64 10.0.22631

I'm reworking how the C/C++ extension populates diagnostics (and inlay hints, semantic tokens, etc.), to progressively populate the document as additional results are available.

It looks like DiagnosticCollection does not currently provide an efficient way to add Diagnostic's to an existing set. It's necessary to get the array of Diagnostics, make a change, then set it again. I'm seeing that, with a large file, and several iterations of augmenting that list of diagnostics, that I get redundant (expensive) requests to provide CodeAction's for Diagnostics that are not 'new'. Also, if the user clicks on that bit of code, they will see the CodeAction lightbulb disappear out from under them when unnecessarily regenerated.

Perhaps this could be addressed by adding an 'add' function to DiagnosticCollection, or maybe keeping a cached list of existing Diagnostics to avoid redundantly requesting CodeActions for.