C#: Introduce a new expr kind for when accessors are invoked directly.

Author: michaelnebel

csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Invocation.cs

@@ -26,6 +26,17 @@ private Invocation(ExpressionNodeInfo info)
 
         private bool IsOperatorCall() => Kind == ExprKind.OPERATOR_INVOCATION;
 
+        private bool IsAccessorInvocation() => Kind == ExprKind.ACCESSOR_INVOCATION;
+
+        private bool IsValidMemberAccessKind()
+        {
+            return Kind == ExprKind.METHOD_INVOCATION ||
+                IsEventDelegateCall() ||
+                IsExplicitDelegateInvokeCall() ||
+                IsOperatorCall() ||
+                IsAccessorInvocation();
+        }
+
         protected override void PopulateExpression(TextWriter trapFile)
         {
             if (IsNameof(Syntax))
@@ -39,7 +50,7 @@ protected override void PopulateExpression(TextWriter trapFile)
             var target = TargetSymbol;
             switch (Syntax.Expression)
             {
-                case MemberAccessExpressionSyntax memberAccess when Kind == ExprKind.METHOD_INVOCATION || IsEventDelegateCall() || IsExplicitDelegateInvokeCall() || IsOperatorCall():
+                case MemberAccessExpressionSyntax memberAccess when IsValidMemberAccessKind():
                     memberName = memberAccess.Name.Identifier.Text;
                     if (Syntax.Expression.Kind() == SyntaxKind.SimpleMemberAccessExpression)
                         // Qualified method call; `x.M()`
@@ -122,6 +133,14 @@ private static bool IsOperatorLikeCall(ExpressionNodeInfo info)
                 original!.MethodKind == MethodKind.UserDefinedOperator;
         }
 
+        private static bool IsAccessorLikeInvocation(ExpressionNodeInfo info)
+        {
+            return info.SymbolInfo.Symbol is IMethodSymbol method &&
+                method.TryGetExtensionMethod(out var original) &&
+                (original!.MethodKind == MethodKind.PropertyGet ||
+                 original!.MethodKind == MethodKind.PropertySet);
+        }
+
         public IMethodSymbol? TargetSymbol
         {
             get
@@ -233,6 +252,10 @@ private static ExprKind GetKind(ExpressionNodeInfo info)
             {
                 return ExprKind.OPERATOR_INVOCATION;
             }
+            if (IsAccessorLikeInvocation(info))
+            {
+                return ExprKind.ACCESSOR_INVOCATION;
+            }
             return ExprKind.METHOD_INVOCATION;
         }
 

csharp/extractor/Semmle.Extraction.CSharp/Kinds/ExprKind.cs

@@ -133,6 +133,7 @@ public enum ExprKind
         COLLECTION = 136,
         SPREAD_ELEMENT = 137,
         INTERPOLATED_STRING_INSERT = 138,
+        ACCESSOR_INVOCATION = 139,
         DEFINE_SYMBOL = 999,
     }
 }

csharp/ql/lib/semmlecode.csharp.dbscheme

@@ -1194,6 +1194,8 @@ case @expr.kind of
 | 136 = @collection_expr
 | 137 = @spread_element_expr
 | 138 = @interpolated_string_insert_expr
+/* C# 14.0 */
+| 139 = @accessor_invocation_expr
 /* Preprocessor */
 | 999 = @define_symbol_expr
 ;
@@ -1268,9 +1270,9 @@ case @expr.kind of
 
 @call = @method_invocation_expr | @constructor_init_expr | @operator_invocation_expr
       | @delegate_invocation_expr | @object_creation_expr | @call_access_expr
-      | @local_function_invocation_expr | @function_pointer_invocation_expr;
+      | @local_function_invocation_expr | @function_pointer_invocation_expr | @accessor_invocation_expr;
 
-@call_access_expr = @property_access_expr | @event_access_expr | @indexer_access_expr;
+@call_access_expr = @property_access_expr | @event_access_expr | @indexer_access_expr | @accessor_invocation_expr;
 
 @late_bindable_expr = @dynamic_element_access_expr | @dynamic_member_access_expr
                     | @object_creation_expr | @method_invocation_expr | @operator_invocation_expr;
@@ -1319,7 +1321,8 @@ dynamic_member_name(
 
 @qualifiable_expr = @member_access_expr
                   | @method_invocation_expr
-                  | @element_access_expr;
+                  | @element_access_expr
+                  | @accessor_invocation_expr;
 
 conditional_access(
   unique int id: @qualifiable_expr ref);