C#: Property- and Indexer call targets for partial overrides.

[michaelnebel]

It appears that call targets for properties and indexers are missing, when only the getter or setter is overridden.
Assume we have

public class BaseClass
{
    public virtual int Value
    {
        get { return field; }
        set { field = value; }
    }
}

public class DerivedClass1 : BaseClass
{
    public override int Value
    {
        get { return 20; }
    }
}

For the example below, we extract an access to the property Value from DerivedClass1. However, only the getter is overridden, which means that the setter being called is the one from BaseClass.

var d1 = new DerivedClass1();
d1.Value = 11;

Furthermore, the function pointer calls are removed from the set of calls where we are interested in reporting missing call targets (as the class of function pointer calls explicitly overrides the getTarget predicate with none()).

[Copilot]

Pull request overview

Improves C# call target resolution for property and indexer accesses when only one accessor (getter or setter) is overridden, and adjusts call-target quality telemetry to exclude delegate-like calls (including function pointer calls) from “missing target” reporting.

Changes:

• Add property/indexer accessor “read/write target” resolution that follows override chains to find the effective getter/setter.
• Update call-target telemetry filtering to exclude DelegateLikeCall rather than only DelegateCall.
• Extend C# library tests (source + expected outputs) and add a change note covering the behavior change.

Show a summary per file

File	Description
csharp/ql/test/library-tests/properties/Properties19.expected	Updates expected call-target results to include correct getter/setter targets for partially overridden properties.
csharp/ql/test/library-tests/properties/Properties17.expected	Updates expected field list to include the synthesized Value.field.
csharp/ql/test/library-tests/properties/properties.cs	Adds a new test scenario covering partial property overrides (getter-only override) and observed call targets.
csharp/ql/test/library-tests/properties/PrintAst.expected	Updates AST expectations for the newly added test classes and property calls.
csharp/ql/src/Telemetry/DatabaseQuality.qll	Excludes DelegateLikeCall from missing-call-target telemetry classification.
csharp/ql/lib/semmle/code/csharp/Property.qll	Adds accessor target resolution helpers for read/write contexts across override chains.
csharp/ql/lib/semmle/code/csharp/exprs/Call.qll	Routes PropertyCall/IndexerCall target resolution through the new property/indexer read/write target logic.
csharp/ql/lib/change-notes/2026-05-22-property-indexer-partial-override.md	Documents the analysis improvement as a minor analysis change.

Copilot's findings

• Files reviewed: 8/8 changed files
• Comments generated: 0

[michaelnebel]

DCA looks good.