Update

Author: svilen-mihaylov-elastic

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/session/FieldNameUtils.java

@@ -109,7 +109,7 @@ public static PreAnalysisResult resolveFieldNames(LogicalPlan parsed, EnrichReso
         var canRemoveAliases = new Holder<>(true);
 
         var forEachDownProcessor = new Holder<BiConsumer<LogicalPlan, Holder<Boolean>>>();
-        processingLambda.set((LogicalPlan p, Holder<Boolean> breakEarly) -> {// go over each plan top-down
+        forEachDownProcessor.set((LogicalPlan p, Holder<Boolean> breakEarly) -> {// go over each plan top-down
             if (p instanceof Fork fork) {
                 // Early return from forEachDown. We will iterate over the children manually and end the recursion via forEachDown early.
                 var forkRefsResult = AttributeSet.builder();
@@ -218,7 +218,7 @@ public static PreAnalysisResult resolveFieldNames(LogicalPlan parsed, EnrichReso
                 });
             }
         });
-        parsed.forEachDownMayReturnEarly(processingLambda.get());
+        parsed.forEachDownMayReturnEarly(forEachDownProcessor.get());
 
         if (projectAll.get()) {
             return new PreAnalysisResult(enrichResolution, IndexResolver.ALL_FIELDS, Set.of());

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/session/FieldNameUtilsTests.java

@@ -73,6 +73,13 @@ public void testDirectFilter() {
         );
     }
 
+    public void testForkEval() {
+        assertFieldNames(
+            "FROM employees | fork (eval x = 1 | keep x) (eval y = 2 | keep y) (eval z = 3 | keep z)",
+            Set.of("*")
+        );
+    }
+
     public void testSort1() {
         assertFieldNames(
             "from employees | sort still_hired, emp_no | keep emp_no, still_hired | limit 3",