A0-1-1: Fix useless assignment false positive on constexpr array size

[fjatWbyT]

Description

Addresses false positive like the one in #690 in another AUTOSAR ule.

Change request type

• [ ] Release or process automation (GitHub workflows, internal scripts)
• [ ] Internal documentation
• [ ] External documentation
• [x] Query files (.ql, .qll, .qls or unit tests)
• [ ] External scripts (analysis report or other code shipped as part of a release)

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• [ ] Queries have been added for the following rules:
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  • A0-1-1

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Author

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Reviewer

• [ ] Have all the relevant rule package description files been checked in?
• [ ] Have you verified that the metadata properties of each new query is set appropriately?
• [ ] Do all the unit tests contain both "COMPLIANT" and "NON_COMPLIANT" cases?
• [ ] Are the alert messages properly formatted and consistent with the style guide?
• [ ] Have you run the queries on OpenPilot and verified that the performance and results are acceptable?
  As a rule of thumb, predicates specific to the query should take no more than 1 minute, and for simple queries be under 10 seconds. If this is not the case, this should be highlighted and agreed in the code review process.
• [ ] Does the query have an appropriate level of in-query comments/documentation?
• [ ] Have you considered/identified possible edge cases?
• [ ] Does the query not reinvent features in the standard library?
• [ ] Can the query be simplified further (not golfed!)

[fjatWbyT]

Hello @lcartey,

I looked for unit tests analogous to the one updated in #690, in this case for A0-1-1 "useless assignment", in contrast with M0-1-9 "no dead code", but couldn't find any already existing. I run locally the (153) tests in cpp/common/test/rules after applying the change and all pass. I could find tests for useless assignment in deviations, but I doubt those need updating for this change since there's no new deviation.

Does it make sense to add explicit coverage for A0-1-1? I wonder if it would be sensible to (a) add a new directory cpp/common/uselessassignment, (b) update configuration so that the ones in cpp/common/deadcode are also run against A0-1-1, or (c) something else :) On the one hand, I think that covering these other isUselessSsaDefinition predicate and InterestingStackVariable class (assuming they aren't already) would be an improvement. On the other hand, since they are (at least partially) used by the dead code qll, it might not be worth further updates.

[lcartey]

Hi @fjatWbyT! Thanks for the PR.

The test cases for A0-1-1 live here: https://github.com/github/codeql-coding-standards/tree/main/cpp/autosar/test/rules/A0-1-1

The tests live in a common directory when one query implementation is shared by multiple rules - for example, where an AUTOSAR and CERT C++ rule cover the same issue. A0-1-1 is only required to be reported to AUTOSAR, so the tests live in the AUTOSAR test directory, under the rule ID.

[fjatWbyT]

Aaah, it is clear now. Thank you very much for the explanation. I will update the PR with extra coverage for this case in that file.