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C#: Allow virtual member access in nameof expressions in cs/virtual-call-in-constructor. #22205

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C#: Allow virtual member access in nameof expressions in cs/virtual-call-in-constructor. #22205

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a549f49
C#: Add nameof virtual method in constructor test case.
michaelnebel Jul 16, 2026
be6f771
C#: Use any instead of exists.
michaelnebel Jul 16, 2026
4d8f150
C#: Allow virtual method/indexer/property/event access in nameof expr…
michaelnebel Jul 16, 2026
f7250f2
C#: Update test expected output.
michaelnebel Jul 16, 2026
b52ea33
C#: Add change-note.
michaelnebel Jul 16, 2026
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13 changes: 6 additions & 7 deletions csharp/ql/src/Bad Practices/VirtualCallInConstructorOrDestructor.ql
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ predicate virtualCallToSelfInConstructor(Expr e) {
(c instanceof Constructor or c instanceof Destructor) and
t = c.getDeclaringType() and
virtualAccessWithThisQualifier(e, d) and
not e = any(NameOfExpr ne).getAccess().getAChildExpr*() and
t.getABaseType*() = d.getDeclaringType() and
not t.isSealed() and
not overriddenSealed(t.getABaseType*(), d)
Expand All @@ -34,17 +35,15 @@ predicate overriddenSealed(RefType t, Virtualizable d) {
}

predicate virtualAccessWithThisQualifier(Expr e, Member d) {
exists(VirtualMethodCall c |
c = e and c.getTarget() = d and c.hasThisQualifier() and not c.isImplicit()
)
e = any(VirtualMethodCall c | c.getTarget() = d and c.hasThisQualifier() and not c.isImplicit())
or
exists(VirtualMethodAccess c | c = e and c.getTarget() = d and c.hasThisQualifier())
e = any(VirtualMethodAccess c | c.getTarget() = d and c.hasThisQualifier())
or
exists(VirtualPropertyAccess c | c = e and c.getTarget() = d and c.hasThisQualifier())
e = any(VirtualPropertyAccess c | c.getTarget() = d and c.hasThisQualifier())
or
exists(VirtualIndexerAccess c | c = e and c.getTarget() = d and c.hasThisQualifier())
e = any(VirtualIndexerAccess c | c.getTarget() = d and c.hasThisQualifier())
or
exists(VirtualEventAccess c | c = e and c.getTarget() = d and c.hasThisQualifier())
e = any(VirtualEventAccess c | c.getTarget() = d and c.hasThisQualifier())
}

from Expr e
Expand Down
4 changes: 4 additions & 0 deletions csharp/ql/src/change-notes/2026-07-16-virtual-call-in-constructor.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
---
category: minorAnalysis
---
* The query `cs/virtual-call-in-constructor` has been improved. Uses of virtual members in `nameof` expressions are no longer reported, since they are not calls.
4 changes: 4 additions & 0 deletions ...ad Practices/VirtualCallInConstructorOrDestructor/VirtualCallInConstructorOrDestructor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ public void f_nonvirtual() { }
public void f_interface() { }

public virtual int p_virtual { get { return 0; } }
public virtual string p_virtual_string { get { return ""; } }
public virtual int p_sealed { get { return 0; } }
public int p_nonvirtual { get { return 0; } }

Expand Down Expand Up @@ -55,11 +56,14 @@ class C : B
a = f_sealed; // GOOD
a = f_nonvirtual; // GOOD
a = f_interface; // GOOD
var f_name = nameof(f_virtual); // GOOD

// Property access
int i = p_virtual; // $ Alert // BAD
i = p_sealed; // GOOD
i = p_nonvirtual; // GOOD
var p_name = nameof(p_virtual_string); // GOOD
var p_length_name = nameof(p_virtual_string.Length); // GOOD

// Indexer access
i = this[0]; // $ Alert // BAD
Expand Down
10 changes: 5 additions & 5 deletions ...ctices/VirtualCallInConstructorOrDestructor/VirtualCallInConstructorOrDestructor.expected
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
| VirtualCallInConstructorOrDestructor.cs:45:13:45:23 | call to method f_virtual | Avoid virtual calls in a constructor or destructor. |
| VirtualCallInConstructorOrDestructor.cs:54:17:54:25 | access to method f_virtual | Avoid virtual calls in a constructor or destructor. |
| VirtualCallInConstructorOrDestructor.cs:60:21:60:29 | access to property p_virtual | Avoid virtual calls in a constructor or destructor. |
| VirtualCallInConstructorOrDestructor.cs:65:17:65:23 | access to indexer | Avoid virtual calls in a constructor or destructor. |
| VirtualCallInConstructorOrDestructor.cs:70:13:70:21 | access to event e_virtual | Avoid virtual calls in a constructor or destructor. |
| VirtualCallInConstructorOrDestructor.cs:46:13:46:23 | call to method f_virtual | Avoid virtual calls in a constructor or destructor. |
| VirtualCallInConstructorOrDestructor.cs:55:17:55:25 | access to method f_virtual | Avoid virtual calls in a constructor or destructor. |
| VirtualCallInConstructorOrDestructor.cs:62:21:62:29 | access to property p_virtual | Avoid virtual calls in a constructor or destructor. |
| VirtualCallInConstructorOrDestructor.cs:69:17:69:23 | access to indexer | Avoid virtual calls in a constructor or destructor. |
| VirtualCallInConstructorOrDestructor.cs:74:13:74:21 | access to event e_virtual | Avoid virtual calls in a constructor or destructor. |
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