Implement Rule 17.6

[lcartey]

Description

Adds a query to identify parameter array types which use the static keyword.

Although the information about static keywords on array types is in the database, it's stored as a specifier on ArrayType. Unfortunately, Types in general do not have separate tuples per use location - instead, each type is stored once in the database. The consequence of this is that if one array type of a particular size and type uses the static keyword, that keyword is associated with all the uses.

This can be observed in the false positive test case int arr4[11] which is flagged because it uses the array type int[11], and we previously declared int arr2[static 11], which has "tainted" the other uses.

I think this is a CodeQL bug, in the sense that under our current model it doesn't make sense to store the static qualifier on the type at all. It could instead be registered on the parameter (possibly as a parameter specifier such as static_array). As Coding Standards only supports a specified version of CodeQL. and we run unit tests before upgrading, any future improvements in this area will be flagged on upgrade and the query can be adjusted at that point.

Change request type

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

Rules with added or modified queries

• No rules added
• Queries have been added for the following rules:
  • Rule 17.6
• Queries have been modified for the following rules:
  • rule number here

Release change checklist

A change note (development_handbook.md#change-notes) is required for any pull request which modifies:

• The structure or layout of the release artifacts.
• The evaluation performance (memory, execution time) of an existing query.
• The results of an existing query in any circumstance.

If you are only adding new rule queries, a change note is not required.

Author: Is a change note required?

• Yes
• No

🚨🚨🚨
Reviewer: Confirm that format of shared queries (not the .qll file, the
.ql file that imports it) is valid by running them within VS Code.

• Confirmed

Reviewer: Confirm that either a change note is not required or the change note is required and has been added.

• Confirmed

Query development review checklist

For PRs that add new queries or modify existing queries, the following checklist should be completed by both the author and reviewer:

Author

• 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!)

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!)

[mbaluda]

Checked on MRVA top1000 and the ratio of false positives is not negligible (maybe 20%).
However, they will only appear when the rule is violated somewhere else in the project, which I think makes it acceptable.
LGTM!