[clang-tidy][NFC] Fix bugprone-unchecked-optional-access warnings in codebase

[zeyi2]

Closes #156151
Assisted-by: Gemini 3 via Gemini CLI

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[vbvictor]

Can we then remove first assert if we still check via if later? (but preserve comment)

[vbvictor]

It feels weird that dataflow framework didn't count it as "validation", could it be a FP?
Later, you used assert(BestConversion && "text"); for the same purpose of validation

[vbvictor]

So dataflow couldn't handle checking for multiple optional values in one go? Seems like FP.

[zeyi2]

It seems that this is actually a FP..

[zeyi2]

Sorry for the postponing, I'll restart working on this soon.

Update: I'm not sure whether we should enable this check. On my PC (Intel(R) Core(TM) 7 250H (20) @ 5.40 GHz
) it took 2305.9s to proceed clang-tools-extra/clang-tidy/utils/LexerUtils.cpp.

Also, I think clang-tools-extra/clang-tidy/cppcoreguidelines/PreferMemberInitializerCheck.cpp requires more than 1 hour to proceed...

The existing fixes can serve as a refactor. WDYT @vbvictor

[zeyi2]

I think this is required, rewriting this to:
if (!parseFileExtensions(getOptions().HeaderFileExtensions.value_or(EmptyFileExtensions),...
causes a test failures, same as the below one.

[zeyi2]

As of AI usage: 67bf385, 8f46670 and 9533351 uses Gemini 3 for code cleanup and pre-commit review. I've manually verified that these changes are reasonable.

[vbvictor]

Sorry for the postponing, I'll restart working on this soon.

No problem, this is actually a good part of open source development when you don't have any deadlines:) So you can pause for as long as you want.

Update: I'm not sure whether we should enable this check. On my PC (Intel(R) Core(TM) 7 250H (20) @ 5.40 GHz ) it took 2305.9s to proceed clang-tools-extra/clang-tidy/utils/LexerUtils.cpp.

Hmm, that is very unfortunate and strange. Did you use optimized build of clang-tidy (installed from apt-get or Release local build)? When I did initial run in #156149 (comment) with all checks enabled, I think it didn't run for very long (ryzen 9950x, 96GB ram). I will double-check later.

Lets keep it disabled for now.

[zeyi2]

Did you use optimized build of clang-tidy (installed from apt-get or Release local build)?

I was using the one built from main branch:

$ ./build/bin/clang-tidy --version
LLVM (http://llvm.org/):
  LLVM version 22.0.0git
  Optimized build with assertions.

The command I use is:

python3 clang-tools-extra/clang-tidy/tool/run-clang-tidy.py \
    -clang-tidy-binary=./build/bin/clang-tidy \
    -checks='-*,bugprone-unchecked-optional-access' \
    -p=./build \
    clang-tools-extra/clang-tidy > clang_tidy_output.log 2>&1

It is possible that this problem is because of my laptop..

I will double-check later.

Thanks!