Fix heap-after-free due to document rescan

[ppizarror]

Hi! First, thanks a lot for this fantastic project. I've been using it for several years.

I often struggle with crashes due to external updates to .tex files. While debugging, I got a use-after-free in LatexDocument::getListOfDocs(). Its result is cached in the project-shared lp->projectDocuments, but the cache was only invalidated in the two setMasterDocument paths. Every other mutation of the document set / master-child graph (deleteDocument, removeDocs, addDocument, addChild/removeChild) left stale.

So, for fixing it, I invalidated lp->projectDocuments on every graph mutation.
To confirm, added a unit test that confirms the exact crash pattern. Greetings!

[sunderme]

Thanks. I will review later this week.

[sunderme]

looks like a lp->projectDocuments.clear(); was added all over the place.
What action exactly leads to a crash ?

[ppizarror]

Hi @sunderme. Often, when TexStudio is opened, and .tex files are rewritten or moved from VS Code (imagine I am using some agent). Or if I have some auto-generated .tex from a Python script, I run that script, regenerate .tex, and then TexStudio crashes.

I am running the latest version on macOS 26.5.1.
To spot the culprit, I just compiled and ran the debug version on my machine. You can see that, without the fix, the unit test I added just collapses to the exact crash I detected.

[sunderme]

the file is open in txs while changed externally ?

[ppizarror]

the file is open in txs while changed externally ?

exactly. that is a much better description 🤔

[sunderme]

Well, I don't get a crash, but let's see.

[sunderme]

I think, I would like to see a (simple) test case to recreate the issue.
Currently I do not see a crash (nor failure to invalidate the cache)

or you can check how it gets to "delete document" in your use case.

[ppizarror]

Sure I will provide a simple test case by the end of the wee. Thanks!

[sunderme]

I still would like to see a real test case.

[sunderme]

can you check if txs still crashes on your end with latest changes ?