[clang-tools-extra] [clang-tidy] Filter out googletest TUs in bugprone-unchecked-optional-access (PR #115051)

[Gábor Horváth via cfe-commits]

Xazax-hun wrote:

I think the ideal solution would be something like using the [analyzer_noreturn](https://clang.llvm.org/docs/AttributeReference.html#analyzer-noreturn) attribute in GTest to mark branches that should not be taken by static analyzers because some invariants failed and every further diagnostics are false positive on that path. This is the solution that the Clang Static Analyzer recommends to users (adding annotations to custom asserts). That being said, there is a precedent of the analyzer recognizing custom assert functions and treating them as noreturn even if they are not annotated: https://github.com/llvm/llvm-project/blob/main/clang/lib/StaticAnalyzer/Checkers/NoReturnFunctionChecker.cpp

If GTest had a similar function for the assert failed paths, a similar approach could be taken for the dataflow framework as well. If there is no such function that we could match on in the expanded code, I don't think we could do anything, we might need to do changes to GTest.

All that being said, I think we want to provide a good experience for people using this popular testing library out of the box, even if they use an older version that does not have any annotations. I am OK with suppressing noisy static analysis results for test files for the time being. It looks like the current options are either leave it broken on tests or turn it off for tests as modeling non-test code is prioritized. As a users I would definitely prefer the latter. 

https://github.com/llvm/llvm-project/pull/115051