Fix const fold

Author: l46kok

optimizer/src/main/java/dev/cel/optimizer/optimizers/ConstantFoldingOptimizer.java

@@ -201,7 +201,7 @@ private boolean canFold(CelNavigableMutableExpr navigableExpr) {
         CelNavigableMutableExpr operand = navigableExpr.children().collect(onlyElement());
         return areChildrenArgConstant(operand);
       case COMPREHENSION:
-        return !isNestedComprehension(navigableExpr);
+        return !isNestedComprehension(navigableExpr) && !containsUnfoldableFunctions(navigableExpr);
       default:
         return false;
     }
@@ -277,6 +277,16 @@ private static boolean isNestedComprehension(CelNavigableMutableExpr expr) {
     return false;
   }
 
+  private boolean containsUnfoldableFunctions(CelNavigableMutableExpr expr) {
+    return expr.descendants()
+        .filter(node -> node.expr().getKind().equals(Kind.CALL))
+        .map(node -> node.expr().call())
+        .anyMatch(
+            call ->
+                !foldableFunctions.contains(call.function())
+        );
+  }
+
   private Optional<CelMutableAst> maybeFold(
       Cel cel, CelMutableAst mutableAst, CelNavigableMutableExpr node)
       throws CelOptimizationException {

optimizer/src/test/java/dev/cel/optimizer/optimizers/ConstantFoldingOptimizerTest.java

@@ -48,6 +48,7 @@
 public class ConstantFoldingOptimizerTest {
   private static final CelOptions CEL_OPTIONS =
       CelOptions.current()
+          .populateMacroCalls(true)
           .enableTimestampEpoch(true)
           .build();
   private static final Cel CEL =
@@ -56,12 +57,23 @@ public class ConstantFoldingOptimizerTest {
           .addVar("y", SimpleType.DYN)
           .addVar("list_var", ListType.create(SimpleType.STRING))
           .addVar("map_var", MapType.create(SimpleType.STRING, SimpleType.STRING))
+          .setStandardMacros(CelStandardMacro.STANDARD_MACROS)
           .addFunctionDeclarations(
               CelFunctionDecl.newFunctionDeclaration(
                   "get_true",
-                  CelOverloadDecl.newGlobalOverload("get_true_overload", SimpleType.BOOL)))
+                  CelOverloadDecl.newGlobalOverload("get_true_overload", SimpleType.BOOL)),
+              CelFunctionDecl.newFunctionDeclaration(
+                  "get_list",
+                  CelOverloadDecl.newGlobalOverload(
+                      "get_list_overload",
+                      ListType.create(SimpleType.INT),
+                      ListType.create(SimpleType.INT)))
+          )
           .addFunctionBindings(
-              CelFunctionBinding.from("get_true_overload", ImmutableList.of(), unused -> true))
+              CelFunctionBinding.from("get_true_overload", ImmutableList.of(), unused -> true),
+              CelFunctionBinding.from(
+                  "get_list_overload", ImmutableList.class, arg -> arg)
+          )
           .addMessageTypes(TestAllTypes.getDescriptor())
           .setContainer(CelContainer.ofName("cel.expr.conformance.proto3"))
           .setOptions(CEL_OPTIONS)
@@ -371,6 +383,8 @@ public void constantFold_macros_withoutMacroCallMetadata(String source) throws E
   @TestParameters("{source: 'x == 42'}")
   @TestParameters("{source: 'timestamp(100)'}")
   @TestParameters("{source: 'duration(\"1h\")'}")
+  @TestParameters("{source: '[true].exists(x, x == get_true())'}")
+  @TestParameters("{source: 'get_list([1, 2]).map(x, x * 2)'}")
   public void constantFold_noOp(String source) throws Exception {
     CelAbstractSyntaxTree ast = CEL.compile(source).getAst();
 

tools/src/test/java/dev/cel/tools/ai/AgenticPolicyCompilerTest.java

@@ -283,6 +283,7 @@ private void runTests(Cel cel, CelAbstractSyntaxTree ast, PolicyTestSuite testSu
                   ? (List<AgentMessage>) inputMap.get("_test_history")
                   : ImmutableList.of();
 
+          @SuppressWarnings("Immutable")
           CelLateFunctionBindings bindings = CelLateFunctionBindings.from(
               CelFunctionBinding.from(
                   "agent_history",