Make string enum to enum shape transform opt-in in CodegenDirector

smithy-codegen-core/src/main/java/software/amazon/smithy/codegen/core/directed/CodegenDirector.java

@@ -97,7 +97,6 @@ public static Model simplifyModelForServiceCodegen(Model model, ShapeId service,
         ServiceShape serviceShape = model.expectShape(service, ServiceShape.class);
         model = transformer.copyServiceErrorsToOperations(model, serviceShape);
         model = transformer.flattenAndRemoveMixins(model);
-        model = transformer.changeStringEnumsToEnumShapes(model, true);
         return model;
     }
 
@@ -238,6 +237,19 @@ public void createDedicatedInputsAndOutputs(String inputSuffix, String outputSuf
         });
     }
 
+    /**
+     * Changes each compatible string shape with the enum trait to an enum shape.
+     *
+     * @param synthesizeEnumNames Whether enums without names should have names synthesized if possible.
+     * @see ModelTransformer#changeStringEnumsToEnumShapes(Model, boolean)
+     */
+    public void changeStringEnumsToEnumShapes(boolean synthesizeEnumNames) {
+        transforms.add((model, transformer) -> {
+            LOGGER.finest("Creating dedicated input and output shapes for directed codegen");
+            return transformer.changeStringEnumsToEnumShapes(model, synthesizeEnumNames);
+        });
+    }
+
     /**
      * Sorts all members of the model prior to codegen.
      *

smithy-codegen-core/src/test/java/software/amazon/smithy/codegen/core/directed/CodegenDirectorTest.java

@@ -18,6 +18,7 @@
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.containsInAnyOrder;
+import static org.hamcrest.Matchers.empty;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -37,6 +38,8 @@ public class CodegenDirectorTest {
 
     private static final class TestDirected implements DirectedCodegen<TestContext, TestSettings, TestIntegration> {
         public final List<ShapeId> generatedShapes = new ArrayList<>();
+        public final List<ShapeId> generatedEnumTypeEnums = new ArrayList<>();
+        public final List<ShapeId> generatedStringTypeEnums = new ArrayList<>();
 
         @Override
         public SymbolProvider createSymbolProvider(CreateSymbolProviderDirective<TestSettings> directive) {
@@ -86,10 +89,15 @@ public void generateUnion(GenerateUnionDirective<TestContext, TestSettings> dire
         public void generateEnumShape(GenerateEnumDirective<TestContext, TestSettings> directive) {
             generatedShapes.add(directive.shape().getId());
             GenerateEnumDirective.EnumType type = directive.getEnumType();
-            if (type == GenerateEnumDirective.EnumType.ENUM) {
-                directive.expectEnumShape();
-            } else {
-                throw new RuntimeException("Expected enum type to be enum shape");
+            switch (type) {
+                case ENUM:
+                    generatedEnumTypeEnums.add(directive.expectEnumShape().getId());
+                    break;
+                case STRING:
+                    generatedStringTypeEnums.add(directive.shape().asStringShape().get().getId());
+                    break;
+                default:
+                    throw new IllegalStateException("Only ENUM and STRING types exist.");
             }
         }
 
@@ -164,6 +172,51 @@ public void performsCodegen() {
                 ShapeId.from("smithy.example#Instruction"),
                 ShapeId.from("smithy.api#Unit")
         ));
+
+        assertThat(testDirected.generatedStringTypeEnums, containsInAnyOrder(
+                ShapeId.from("smithy.example#Status")
+        ));
+        assertThat(testDirected.generatedEnumTypeEnums, empty());
+    }
+
+    @Test
+    public void performsCodegenWithStringEnumsChangedToEnumShapes() {
+        TestDirected testDirected = new TestDirected();
+        CodegenDirector<TestWriter, TestIntegration, TestContext, TestSettings> runner
+                = new CodegenDirector<>();
+        FileManifest manifest = new MockManifest();
+        Model model = Model.assembler()
+                .addImport(getClass().getResource("directed-model.smithy"))
+                .assemble()
+                .unwrap();
+
+        runner.settings(new TestSettings());
+        runner.directedCodegen(testDirected);
+        runner.fileManifest(manifest);
+        runner.service(ShapeId.from("smithy.example#Foo"));
+        runner.model(model);
+        runner.integrationClass(TestIntegration.class);
+        runner.performDefaultCodegenTransforms();
+        runner.changeStringEnumsToEnumShapes(true);
+        runner.createDedicatedInputsAndOutputs();
+        runner.sortMembers();
+        runner.run();
+
+        // asserts that mixin smithy.example#Paginated is not generated
+        assertThat(testDirected.generatedShapes, containsInAnyOrder(
+                ShapeId.from("smithy.example#Foo"),
+                ShapeId.from("smithy.example#TheFoo"),
+                ShapeId.from("smithy.example#ListFooInput"),
+                ShapeId.from("smithy.example#ListFooOutput"),
+                ShapeId.from("smithy.example#Status"),
+                ShapeId.from("smithy.example#Instruction"),
+                ShapeId.from("smithy.api#Unit")
+        ));
+
+        assertThat(testDirected.generatedEnumTypeEnums, containsInAnyOrder(
+                ShapeId.from("smithy.example#Status")
+        ));
+        assertThat(testDirected.generatedStringTypeEnums, empty());
     }
 
     @Test