[clang] [clang][analyzer] CallAndMessage warnings at pointer to uninitialized struct (PR #164600)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat commented:

I admit that my first impression is that "I don't know" -- I'm not familiar enough with the possible representations of undefined values in the analyzer to form an opinion about this PR. I could research this if it is really needed -- but perhaps @steakhal @haoNoQ or @Xazax-hun could review this more quickly?

My first impression is that I feel that the old code should have been sufficient to detect whether the memory area is undefined -- and it is a bit sad that you need to write this more elaborate code. In general, I tend to notice a pattern that `LazyCompoundVal` is too opaque and its performance benefits come with lots of added code complexity as we always need to explicitly check for it. (However I don't know enough, perhaps this is still the least wrong approach.)

https://github.com/llvm/llvm-project/pull/164600