[clang] [analyzer] Fix crash in PaddingChecker on dependent field types (PR #232986)

[Balázs Benics via cfe-commits]

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+// RUN: %clang_analyze_cc1 -std=c++20 -analyzer-checker=optin.performance -verify %s
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steakhal wrote:

@redcode Thank you for your detailed reply. All great!
>Moving it to clang/test/Analysis/padding_cpp.cpp would need to bump the file to C++20, since the repro needs abbreviated function templates. Is that OK?

I think I'd prefer bumping and merging the files - although I haven't looked if the existing test has anything that would be an issue.

@benedekaibas right - https://github.com/llvm/llvm-project/pull/232986/changes#r4303935723.

https://github.com/llvm/llvm-project/pull/232986