Rust: Make RefExpr an Operation.

rust/ql/lib/codeql/rust/elements/internal/RefExprImpl.qll

@@ -5,6 +5,7 @@
  */
 
 private import codeql.rust.elements.internal.generated.RefExpr
+private import codeql.rust.elements.internal.OperationImpl::Impl as OperationImpl
 
 /**
  * INTERNAL: This module contains the customizable definition of `RefExpr` and should not
@@ -21,11 +22,15 @@ module Impl {
    *     let raw_mut: &mut i32 = &raw mut foo;
    * ```
    */
-  class RefExpr extends Generated::RefExpr {
+  class RefExpr extends Generated::RefExpr, OperationImpl::Operation {
     override string toStringImpl() {
       result = "&" + concat(int i | | this.getSpecPart(i), " " order by i)
     }
 
+    override string getOperatorName() { result = "&" }
+
+    override Expr getAnOperand() { result = this.getExpr() }
+
     private string getSpecPart(int index) {
       index = 0 and this.isRaw() and result = "raw"
       or

rust/ql/test/library-tests/operations/test.rs

@@ -50,7 +50,7 @@ fn test_operations(
 
 	// miscellaneous expressions that might be operations
 	*ptr; // $ Operation Op=* Operands=1 PrefixExpr DerefExpr
-	&x; // $ RefExpr
+	&x; // $ Operation Op=& Operands=1 RefExpr MISSING: PrefixExpr
 	res?;
 
 	return Ok(());