[clang] [analyzer] Fix StackAddrEscapeChecker crash on temporary object fields (PR #66493)

[Balazs Benics via cfe-commits]

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@@ -398,7 +400,7 @@ void StackAddrEscapeChecker::checkEndFunction(const ReturnStmt *RS,
     }(Referrer->getMemorySpace());
 
     // This cast supposed to succeed.
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steakhal wrote:

I was thinking about it once you raised this comment.
To me, to have a proper diagnostic we need something that we can name here; and they are usually variables.

Now, if we check and bail out if it's not a VarRegion, we would not get notified if we suddenly have some other value that we could cover but we don't. It took a long time to even hit this crash, so I don't think they are too frequent.

So the question is which we prefer:
 - Crash (possible in the long future) to get notified or
 - Silently ignore these unthought, interesting cases for which we didn't account for
 
 If this would be a mission-critical software I'd vote for (2), but now I'm a bit hesitant in between the two options.
 
 Maybe, given that this is a core checker, we should lean towards gracefully handling this. WDYT?

https://github.com/llvm/llvm-project/pull/66493