Fix #14075 (False positive: unusedStructMember, member usage by alignas is ignored)

[danmar]

This should be reviewed extra carefully; I used ai to fix the ticket.

[Copilot]

Pull Request Overview

This PR fixes a false positive in the unused struct member checker where members referenced in alignas attributes were incorrectly flagged as unused. The fix adds detection for member usage within alignas expressions.

• Added logic to detect struct member references in alignas attributes
• Added test case to verify the fix for issue #14075

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
test/testunusedvar.cpp	Added test case structmember29 to verify alignas member usage detection
lib/checkunusedvar.cpp	Added code to check for member references in alignas attributes

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[danmar]

@firewave you reacted with a thumb down, do you see any problem here that I don't see?

[danmar]

This should be reviewed extra carefully; I used ai to fix the ticket.

[firewave]

@firewave you reacted with a thumb down, do you see any problem here that I don't see?

Yes, I read the summary and I had to double-check that what it wrote actually matches what is contained in the PR. It turned out it is basically just the title and the comment blown up, so it adds nothing at all and is just a waste of time and resources.

This should be reviewed extra carefully; I used ai to fix the ticket.

In this case I would like to have that stated somewhere very clearly and I would even like to have such commits annotated with something which can be searched for in the commit log. As Cppcheck is a security-related tool which handles confidential data I think that might be worth pointing out.

FYI I am 100% and totally against any usage of it at all. I think it should never be allowed to write any code which will make it into production. I do see the potential in the area of testing (heck, fuzzing is still controversial in this project and it is essentially the same) but it is not worth any of the cost it implies - at least for me. And that is all I am gonna to say about it.

[danmar]

Yes, I read the summary and I had to double-check that what it wrote actually matches what is contained in the PR.

yes the summary is pointless but sometimes copilot has good comments about the changes.. I invoked it to get a review.

I do see the potential in the area of testing

I agree it can be used for different things and we do not have to rule out all usages.