Merge pull request #22205 from michaelnebel/csharp/nameofvirtualincons

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

Author: michaelnebel

csharp/ql/src/Bad Practices/VirtualCallInConstructorOrDestructor.ql

@@ -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)
@@ -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

csharp/ql/src/change-notes/2026-07-16-virtual-call-in-constructor.md

@@ -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.

csharp/ql/test/query-tests/Bad Practices/VirtualCallInConstructorOrDestructor/VirtualCallInConstructorOrDestructor.cs

@@ -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; } }
 
@@ -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

csharp/ql/test/query-tests/Bad Practices/VirtualCallInConstructorOrDestructor/VirtualCallInConstructorOrDestructor.expected

@@ -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. |