Enum shapes

smithy-build/src/main/java/software/amazon/smithy/build/transforms/ChangeTypes.java

@@ -22,6 +22,7 @@
 import software.amazon.smithy.model.Model;
 import software.amazon.smithy.model.shapes.ShapeId;
 import software.amazon.smithy.model.shapes.ShapeType;
+import software.amazon.smithy.model.transform.ModelTransformer;
 
 /**
  * {@code changeType} is used to change the type of one or more shapes.
@@ -80,7 +81,13 @@ protected Model transformWithConfig(TransformContext context, Config config) {
             throw new SmithyBuildException(getName() + ": shapeTypes must not be empty");
         }
 
+        if (config.getSynthesizeEnumNames()) {
+            return context.getTransformer().changeShapeType(
+                    context.getModel(), config.getShapeTypes(),
+                    ModelTransformer.ChangeShapeTypeOption.SYNTHESIZE_ENUM_NAMES);
+        }
+
         return context.getTransformer().changeShapeType(
-                context.getModel(), config.getShapeTypes(), config.getSynthesizeEnumNames());
+                context.getModel(), config.getShapeTypes());
     }
 }

smithy-model/src/main/java/software/amazon/smithy/model/transform/ModelTransformer.java

@@ -497,12 +497,17 @@ public Model changeShapeType(Model model, Map<ShapeId, ShapeType> shapeToType) {
      *
      * @param model Model to transform.
      * @param shapeToType Map of shape IDs to the new type to use for the shape.
-     * @param synthesizeEnumNames Whether enums without names should have names synthesized if possible.
+     * @param changeShapeTypeOptions An array of options to enable when changing types.
      * @return Returns the transformed model.
      * @throws ModelTransformException if an incompatible type transform is attempted.
      */
-    public Model changeShapeType(Model model, Map<ShapeId, ShapeType> shapeToType, boolean synthesizeEnumNames) {
-        return new ChangeShapeType(shapeToType, synthesizeEnumNames).transform(this, model);
+    public Model changeShapeType(
+            Model model,
+            Map<ShapeId, ShapeType> shapeToType,
+            ChangeShapeTypeOption... changeShapeTypeOptions
+    ) {
+        boolean synthesizeNames = ChangeShapeTypeOption.SYNTHESIZE_ENUM_NAMES.hasFeature(changeShapeTypeOptions);
+        return new ChangeShapeType(shapeToType, synthesizeNames).transform(this, model);
     }
 
     /**
@@ -617,4 +622,24 @@ public Model createDedicatedInputAndOutput(Model model, String inputSuffix, Stri
     public Model flattenAndRemoveMixins(Model model) {
         return new FlattenAndRemoveMixins().transform(this, model);
     }
+
+    /**
+     * Options that can be enabled when changing shape types.
+     */
+    public enum ChangeShapeTypeOption {
+        /**
+         * Enables synthesizing enum names when changing a string shape to an enum shape and the
+         * string shape's {@link EnumTrait} doesn't have names.
+         */
+        SYNTHESIZE_ENUM_NAMES;
+
+        boolean hasFeature(ChangeShapeTypeOption[] haystack) {
+            for (ChangeShapeTypeOption feature : haystack) {
+                if (feature == this) {
+                    return true;
+                }
+            }
+            return false;
+        }
+    }
 }