C++: Retrieve namespace attributes

[IdrissRio]

• This PR changes the dbscheme. It adds a new table namespaceattributes to store namespace attributes.
• Add a predicate getAnAttribute to Namespace to retrieve a namespace attribute.

[Copilot]

Pull Request Overview

This PR introduces support for storing and querying attributes on C++ namespaces by adding a new database table and a corresponding QL predicate.

• Add namespaceattributes table to the database schema for mapping namespaces to attribute specs
• Implement getAnAttribute in Namespace.qll to fetch namespace attributes
• Update upgrade/downgrade scripts and change notes to reflect the new feature

Reviewed Changes

Copilot reviewed 5 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
cpp/ql/lib/upgrades/.../upgrade.properties	Add description and backwards compatibility for the new upgrade
cpp/ql/lib/semmlecode.cpp.dbscheme	Define new namespaceattributes table with refs to namespace and attribute
cpp/ql/lib/semmle/code/cpp/Namespace.qll	Implement getAnAttribute predicate in the Namespace class
cpp/ql/lib/change-notes/2025-06-16-namespace-attributes.md	Document the addition of namespace attribute support
cpp/downgrades/.../upgrade.properties	Add downgrade step to remove namespaceattributes table

Comments suppressed due to low confidence (2)

cpp/ql/lib/semmle/code/cpp/Namespace.qll:104

• There are no tests covering this new predicate. Consider adding QueryTest cases to verify that getAnAttribute correctly retrieves attributes for namespaces under various scenarios.

Attribute getAnAttribute() {

cpp/ql/lib/semmle/code/cpp/Namespace.qll:103

• [nitpick] The doc comment could be more precise about the behavior: does it return all attributes or just one? Also clarify what happens if a namespace has no attributes.

/** Gets an attribute of this namespace. */

[Copilot]

The predicate call isn’t assigned to the result variable, so the method won’t return any values. It should read:

result = namespaceattributes(underlyingElement(this), unresolveElement(result));

Suggested change

	namespaceattributes(underlyingElement(this), unresolveElement(result))
	result = namespaceattributes(underlyingElement(this), unresolveElement(result))

[jketema]

Could you add a new test directory to cpp/ql/test/library-tests/attributes that has a test in it that uses the new predicate?

[IdrissRio]

Could you add a new test directory to cpp/ql/test/library-tests/attributes that has a test in it that uses the new predicate?

I added the tests as you suggested. I noticed that some namespaces show up with the location file://:0:0:0:0, while others point to the actual test file (see below). I'm not sure why this happens, but it doesn't seem related to the attributes.

| file://:0:0:0:0 | NamespaceTest | test.cpp:3:26:3:37 | maybe_unused |
| test.cpp:4:53:4:61 | MultiAttr | test.cpp:4:26:4:35 | deprecated |

[jketema]

Looks like that has to do with there being multiple namespace declarations vs just one.

[jketema]

LGTM.