Fix reserved variable availability in lambdas in Painless

modules/lang-painless/src/main/java/org/elasticsearch/painless/Locals.java

@@ -54,11 +54,21 @@ public final class Locals {
     /** Reserved word: unused */
     public static final String DOC    = "doc";
 
-    /** Map of always reserved keywords */
+    /** Map of always reserved keywords for the main scope */
-    public static final Set<String> KEYWORDS = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
+    public static final Set<String> MAIN_KEYWORDS = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
         THIS,PARAMS,SCORER,DOC,VALUE,SCORE,CTX,LOOP
     )));
 
+    /** Map of always reserved keywords for a function scope */
+    public static final Set<String> FUNCTION_KEYWORDS = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
+        THIS,LOOP
+    )));
+
+    /** Map of always reserved keywords for a lambda scope */
+    public static final Set<String> LAMBDA_KEYWORDS = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(
+        THIS,LOOP
+    )));
+
     /** Creates a new local variable scope (e.g. loop) inside the current scope */
     public static Locals newLocalScope(Locals currentScope) {
         return new Locals(currentScope);
@@ -71,7 +81,7 @@ public final class Locals {
      */
     public static Locals newLambdaScope(Locals programScope, Type returnType, List<Parameter> parameters,
                                         int captureCount, int maxLoopCounter) {
-        Locals locals = new Locals(programScope, returnType);
+        Locals locals = new Locals(programScope, returnType, LAMBDA_KEYWORDS);
         for (int i = 0; i < parameters.size(); i++) {
             Parameter parameter = parameters.get(i);
             // TODO: allow non-captures to be r/w:
@@ -90,7 +100,7 @@ public final class Locals {
 
     /** Creates a new function scope inside the current scope */
     public static Locals newFunctionScope(Locals programScope, Type returnType, List<Parameter> parameters, int maxLoopCounter) {
-        Locals locals = new Locals(programScope, returnType);
+        Locals locals = new Locals(programScope, returnType, FUNCTION_KEYWORDS);
         for (Parameter parameter : parameters) {
             locals.addVariable(parameter.location, parameter.type, parameter.name, false);
         }
@@ -103,7 +113,7 @@ public final class Locals {
 
     /** Creates a new main method scope */
     public static Locals newMainMethodScope(Locals programScope, boolean usesScore, boolean usesCtx, int maxLoopCounter) {
-        Locals locals = new Locals(programScope, Definition.OBJECT_TYPE);
+        Locals locals = new Locals(programScope, Definition.OBJECT_TYPE, MAIN_KEYWORDS);
         // This reference.  Internal use only.
         locals.defineVariable(null, Definition.getType("Object"), THIS, true);
 
@@ -140,7 +150,7 @@ public final class Locals {
 
     /** Creates a new program scope: the list of methods. It is the parent for all methods */
     public static Locals newProgramScope(Collection<Method> methods) {
-        Locals locals = new Locals(null, null);
+        Locals locals = new Locals(null, null, null);
         for (Method method : methods) {
             locals.addMethod(method);
         }
@@ -188,7 +198,7 @@ public final class Locals {
         if (hasVariable(name)) {
             throw location.createError(new IllegalArgumentException("Variable [" + name + "] is already defined."));
         }
-        if (KEYWORDS.contains(name)) {
+        if (keywords.contains(name)) {
             throw location.createError(new IllegalArgumentException("Variable [" + name + "] is reserved."));
         }
         return defineVariable(location, type, name, readonly);
@@ -214,6 +224,8 @@ public final class Locals {
     private final Locals parent;
     // return type of this scope
     private final Type returnType;
+    // keywords for this scope
+    private final Set<String> keywords;
     // next slot number to assign
     private int nextSlotNumber;
     // variable name -> variable
@@ -225,15 +237,16 @@ public final class Locals {
      * Create a new Locals
      */
     private Locals(Locals parent) {
-        this(parent, parent.getReturnType());
+        this(parent, parent.returnType, parent.keywords);
     }
 
     /**
      * Create a new Locals with specified return type
      */
-    private Locals(Locals parent, Type returnType) {
+    private Locals(Locals parent, Type returnType, Set<String> keywords) {
         this.parent = parent;
         this.returnType = returnType;
+        this.keywords = keywords;
         if (parent == null) {
             this.nextSlotNumber = 0;
         } else {

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/SFunction.java

@@ -53,9 +53,6 @@ import static org.elasticsearch.painless.WriterConstants.CLASS_TYPE;
  */
 public final class SFunction extends AStatement {
     public static final class FunctionReserved implements Reserved {
-        public static final String THIS = "#this";
-        public static final String LOOP = "#loop";
-
         private int maxLoopCounter = 0;
 
         public void markReserved(String name) {
@@ -63,7 +60,7 @@ public final class SFunction extends AStatement {
         }
 
         public boolean isReserved(String name) {
-            return name.equals(THIS) || name.equals(LOOP);
+            return Locals.FUNCTION_KEYWORDS.contains(name);
         }
 
         @Override
@@ -173,7 +170,7 @@ public final class SFunction extends AStatement {
         }
 
         if (reserved.getMaxLoopCounter() > 0) {
-            loop = locals.getVariable(null, FunctionReserved.LOOP);
+            loop = locals.getVariable(null, Locals.LOOP);
         }
     }
 

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/SSource.java

@@ -89,7 +89,7 @@ public final class SSource extends AStatement {
 
         @Override
         public boolean isReserved(String name) {
-            return Locals.KEYWORDS.contains(name);
+            return Locals.MAIN_KEYWORDS.contains(name);
         }
 
         public boolean usesScore() {

modules/lang-painless/src/test/java/org/elasticsearch/painless/LambdaTests.java

@@ -19,6 +19,9 @@
 
 package org.elasticsearch.painless;
 
+import java.util.HashMap;
+import java.util.Map;
+
 public class LambdaTests extends ScriptTestCase {
 
     public void testNoArgLambda() {
@@ -204,4 +207,28 @@ public class LambdaTests extends ScriptTestCase {
     public void testLambdaCaptureFunctionParam() {
         assertEquals(5, exec("def foo(int x) { Optional.empty().orElseGet(() -> x) } return foo(5);"));
     }
+
+    public void testReservedCapture() {
+        String compare = "boolean compare(Supplier s, def v) {s.get() == v}";
+        assertEquals(true, exec(compare + "compare(() -> new ArrayList(), new ArrayList())"));
+        assertEquals(true, exec(compare + "compare(() -> { new ArrayList() }, new ArrayList())"));
+
+        Map<String, Object> params = new HashMap<>();
+        params.put("key", "value");
+        params.put("number", 2);
+
+        assertEquals(true, exec(compare + "compare(() -> { return params['key'] }, 'value')", params, true));
+        assertEquals(false, exec(compare + "compare(() -> { return params['nokey'] }, 'value')", params, true));
+        assertEquals(true, exec(compare + "compare(() -> { return params['nokey'] }, null)", params, true));
+        assertEquals(true, exec(compare + "compare(() -> { return params['number'] }, 2)", params, true));
+        assertEquals(false, exec(compare + "compare(() -> { return params['number'] }, 'value')", params, true));
+        assertEquals(false, exec(compare + "compare(() -> { if (params['number'] == 2) { return params['number'] }" +
+            "else { return params['key'] } }, 'value')", params, true));
+        assertEquals(true, exec(compare + "compare(() -> { if (params['number'] == 2) { return params['number'] }" +
+            "else { return params['key'] } }, 2)", params, true));
+        assertEquals(true, exec(compare + "compare(() -> { if (params['number'] == 1) { return params['number'] }" +
+            "else { return params['key'] } }, 'value')", params, true));
+        assertEquals(false, exec(compare + "compare(() -> { if (params['number'] == 1) { return params['number'] }" +
+            "else { return params['key'] } }, 2)", params, true));
+    }
 }

modules/lang-painless/src/test/resources/rest-api-spec/test/plan_a/20_scriptfield.yaml

@@ -34,7 +34,32 @@ setup:
                                 x: "bbb"
 
     - match: { hits.hits.0.fields.bar.0: "aaabbb"}
+---
+"Scripted Field Doing Compare":
+    - do:
+        search:
+            body:
+                script_fields:
+                    bar:
+                        script:
+                            inline: "boolean compare(Supplier s, def v) {return s.get() == v;}
+                                     compare(() -> { return doc['foo'].value }, params.x);"
+                            params:
+                                x: "aaa"
 
+    - match: { hits.hits.0.fields.bar.0: true}
+    - do:
+        search:
+            body:
+                script_fields:
+                    bar:
+                        script:
+                            inline: "boolean compare(Supplier s, def v) {return s.get() == v;}
+                                     compare(() -> { return doc['foo'].value }, params.x);"
+                            params:
+                                x: "bbb"
+
+    - match: { hits.hits.0.fields.bar.0: false}
 ---
 "Scripted Field with a null safe dereference (non-null)":
     - do: