Stop tracking removed files and modules

[szajbus]

After a file is removed

• its md5 should not be tracked anymore and
• its module should not be tracked in mod_deps

[axelson]

Hi, thanks for the PR! Can you explain a little bit about what problems occur without this change and why this is needed in addition to the removal that happens on line 351?

elixir-ls/apps/language_server/lib/language_server/dialyzer.ex

Line 351 in 457e16d

mod_deps = Map.drop(mod_deps, MapSet.to_list(stale_modules))

[szajbus]

Hi,
I added some extra JsonRPC calls to get more output from ElixirLS in vs code and I noticed that a file I already removed is still being tracked (passed in state.removed_files to compile/2 on each build).

The expected behaviour would be to stop tracking removed files.

This was done by removing file's md5 hash from md5 map that is used by ElixirLS.LanguageServer.Dialyzer to identify changed and removed files on builds.

But there's also mod_deps map that is tracking module dependencies (as provided by :dialyzer_analysis_callgraph) so that we can reanalyze changed modules and also their dependants.

When a module is removed we should stop tracking it as a dependency of other modules, because it may lead to their unnecessary reanalysis.

(On a side note, I think there may still be some issue with the module deps tracking, because it sometimes reanalyzes less modules than are actually recompiled after a change. That was the reason I started "digging" in the first place, but didn't fully resolve it yet)

[axelson]

Thanks for tracking this down and the writeup! ❤️ Would be great to have tests for this but that's not really feasible at the moment. Perhaps more tests can be added later.