Enable eliminateAllFunctions by default in SubexpressionOptimizer

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

@@ -755,12 +755,13 @@ public abstract static class Builder {
 
       /**
        * Adds a collection of custom functions that will be a candidate for common subexpression
-       * elimination. By default, standard functions are eliminable.
+       * elimination. Only takes effect with {@code eliminateAllFunctions(false)}, where standard
+       * functions are eliminable by default.
        *
        * <p>Note that the implementation of custom functions must be free of side effects.
        *
-       * @deprecated Use {@code eliminateAllFunctions(true)} and {@link #addNonEliminableFunctions}
-       *     to exclude functions with side effects instead.
+       * @deprecated Use {@link #addNonEliminableFunctions} to exclude functions with side effects
+       *     instead.
        */
       @Deprecated
       @CanIgnoreReturnValue
@@ -781,7 +782,7 @@ public Builder addEliminableFunctions(String... functions) {
 
       /**
        * Treats all functions, including custom ones, as candidates for common subexpression
-       * elimination. Functions with side effects must be excluded via {@link
+       * elimination (enabled by default). Functions with side effects must be excluded via {@link
        * #addNonEliminableFunctions}.
        */
       public abstract Builder eliminateAllFunctions(boolean value);
@@ -807,7 +808,7 @@ public static Builder newBuilder() {
           .iterationLimit(500)
           .enableCelBlock(true)
           .populateMacroCalls(false)
-          .eliminateAllFunctions(false);
+          .eliminateAllFunctions(true);
     }
 
     SubexpressionOptimizerOptions() {}

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

@@ -222,10 +222,6 @@ private enum CseNoOpTestCase {
     // Constants and identifiers within a function
     CONST_WITHIN_FUNCTION("size(\"hello\" + \"hello\" + \"hello\")"),
     IDENT_WITHIN_FUNCTION("string(x + x + x)"),
-    // Non-standard functions that have not been explicitly added as a candidate are not
-    // optimized.
-    NON_STANDARD_FUNCTION_1("non_pure_custom_func(1) + non_pure_custom_func(1)"),
-    NON_STANDARD_FUNCTION_2("1 + non_pure_custom_func(1) + 1 + non_pure_custom_func(1)"),
     // Duplicated but nested calls.
     NESTED_FUNCTION("int(timestamp(int(timestamp(1000000000))))"),
     // This cannot be optimized. Extracting the common subexpression would presence test
@@ -265,19 +261,35 @@ public void cse_withCelBlock_noop(@TestParameter CseNoOpTestCase testCase) throw
   }
 
   @Test
-  public void cse_eliminateAllFunctions_customFunctionEliminated() throws Exception {
+  public void cse_customFunction_eliminatedByDefault() throws Exception {
     CelAbstractSyntaxTree ast =
         cel.compile("non_pure_custom_func(1) + non_pure_custom_func(1)").getAst();
 
     CelAbstractSyntaxTree optimizedAst =
-        newCseOptimizer(
-                SubexpressionOptimizerOptions.newBuilder().eliminateAllFunctions(true).build())
-            .optimize(ast);
+        newCseOptimizer(SubexpressionOptimizerOptions.newBuilder().build()).optimize(ast);
 
     assertThat(CEL_UNPARSER.unparse(optimizedAst))
         .isEqualTo("cel.@block([non_pure_custom_func(1)], @index0 + @index0)");
   }
 
+  @Test
+  public void cse_eliminateAllFunctionsDisabled_customFunctionRetained(
+      @TestParameter({
+            "non_pure_custom_func(1) + non_pure_custom_func(1)",
+            "1 + non_pure_custom_func(1) + 1 + non_pure_custom_func(1)"
+          })
+          String source)
+      throws Exception {
+    CelAbstractSyntaxTree ast = cel.compile(source).getAst();
+
+    CelAbstractSyntaxTree optimizedAst =
+        newCseOptimizer(
+                SubexpressionOptimizerOptions.newBuilder().eliminateAllFunctions(false).build())
+            .optimize(ast);
+
+    assertThat(CEL_UNPARSER.unparse(optimizedAst)).isEqualTo(source);
+  }
+
   @Test
   public void cse_eliminateAllFunctions_nonEliminableFunctionRetained() throws Exception {
     CelAbstractSyntaxTree ast =

policy/src/test/java/dev/cel/policy/PolicyTestHelper.java

@@ -87,12 +87,11 @@ enum TestYamlPolicy {
     RESTRICTED_DESTINATIONS(
         "restricted_destinations",
         false,
-        "cel.@block([request.auth.claims, has(@index0.nationality), resource.labels.location in"
+        "cel.@block([request.auth.claims, has(@index0.nationality), locationCode(destination.ip) in"
+            + " spec.restricted_destinations || resource.labels.location in"
             + " spec.restricted_destinations], (@index1 && @index0.nationality == spec.origin &&"
-            + " (locationCode(destination.ip) in spec.restricted_destinations || @index2)) ? true :"
-            + " ((!@index1 && locationCode(origin.ip) == spec.origin &&"
-            + " (locationCode(destination.ip) in spec.restricted_destinations || @index2)) ? true :"
-            + " false))"),
+            + " @index2) ? true : ((!@index1 && locationCode(origin.ip) == spec.origin && @index2)"
+            + " ? true : false))"),
     K8S(
         "k8s",
         true,