[clang] [llvm] Adapted MemRegion::getDescriptiveName to handle ElementRegions (PR #85104)

[Balazs Benics via cfe-commits]

steakhal wrote:

> Hello @steakhal, I have just looked through the changes again. What is the advantage of using checkPreCall instead of checkLocation? I would very much appreciate some background information. Thanks for your help!

Oh yes, I should have explained.
So, `checkLocation` can be triggered for all loads and store operations. Each time in the AST you have a `LValueToRValue` cast for reads, and others for write operations. This means that you can't really define a test where you have clear control of what region you wanted to dump.

Using `PreCall`, you can have your own API, that does what you think, exactly when it encounters that call.
This is similar to what we do in the `ExprInspection` checker, where we have analyzer debug intrinsics defined. Such as `clang_analyzer_dump(T)`. Search for it in the tests, and you will see what I'm talking about.

There is one more benefit of doing this way: There is already a communication channel for the stringified descriptive name: diagnostics.
One can easily capture and compare the diagnostics, like in the rest of the tests.

I was happy to help as I don't expect new contributors to be really involved with our specific testing.
To me what moved the needle was: well described expectation, well described and reproducible actual outcome. You even provided a fix, so I figured I'll help out with the rest.

Ask me if there is anything I left out.

https://github.com/llvm/llvm-project/pull/85104