Support service renames when flattening namespaces

docs/source/1.0/guides/building-models/build-config.rst

@@ -894,9 +894,13 @@ namespace. Shapes not connected to a service will not be flattened.
         separate :ref:`service closures <service-closure>`.
 
 The following example will flatten the namespaces of the shapes connected to
-the ``ns.bar#MyService`` service into the target namespace, ``ns.foo``. Shapes
-tagged with ``baz`` or ``qux`` will also be flattened into the ``ns.foo``
-namespace, so long as they don't conflict with a shape within the :ref:`service closure <service-closure>`.
+the ``ns.bar#MyService`` service into the target namespace, ``ns.foo``. All
+shapes within :ref:`service closure <service-closure>` with be flattened into
+the target namespace, including shapes that have been renamed to disambiguate
+them through the service shape's ``rename`` property. Shapes tagged with
+``baz`` or ``qux`` will also be flattened into the ``ns.foo`` namespace, so
+long as they don't conflict with a shape within the
+:ref:`service closure <service-closure>`.
 
 .. tabs::
 

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

@@ -164,9 +164,18 @@ private Map<ShapeId, ShapeId> getRenamedShapesConnectedToService(Config config,
         return shapeWalker.walkShapes(service).stream()
                 .filter(FunctionalUtils.not(Prelude::isPreludeShape))
                 .map(shape -> Pair.of(shape.getId(), updateNamespace(shape.getId(), config.getNamespace())))
+                .map(pair -> applyServiceRenames(pair, service))
                 .collect(Collectors.toMap(Pair::getLeft, Pair::getRight));
     }
 
+    private Pair<ShapeId, ShapeId> applyServiceRenames(Pair<ShapeId, ShapeId> pair, ServiceShape service) {
+        if (!service.getRename().containsKey(pair.getLeft())) {
+            return pair;
+        }
+        ShapeId newId = ShapeId.fromParts(pair.getRight().getNamespace(), service.getRename().get(pair.getLeft()));
+        return Pair.of(pair.getLeft(), newId);
+    }
+
     private Set<ShapeId> getTaggedShapesToInclude(Set<String> tags, Model model) {
         return model.shapes()
                 .filter(FunctionalUtils.not(Prelude::isPreludeShape))

smithy-build/src/test/java/software/amazon/smithy/build/transforms/FlattenNamespacesTest.java

@@ -116,6 +116,33 @@ public void doesNotIncludeAdditionalTaggedShapesWhenTheyConflict() throws Except
                 "ns.baz#MyOperationOutput$foo", "ns.qux#UnconnectedFromService")));
     }
 
+    @Test
+    public void supportsRenamesOnService() throws Exception {
+        Model model = Model.assembler()
+                .addImport(Paths.get(getClass().getResource("flatten-namespaces-with-renames.json").toURI()))
+                .assemble()
+                .unwrap();
+        ObjectNode config = Node.objectNode()
+                .withMember("namespace", Node.from("ns.qux"))
+                .withMember("service", Node.from("ns.foo#MyService"));
+        TransformContext context = TransformContext.builder()
+                .model(model)
+                .settings(config)
+                .build();
+        Model result = new FlattenNamespaces().transform(context);
+        List<String> ids = result.shapes()
+                .filter(FunctionalUtils.not(Prelude::isPreludeShape))
+                .map(Shape::getId)
+                .map(Object::toString)
+                .collect(Collectors.toList());
+
+        assertThat(ids, containsInAnyOrder("ns.qux#MyService", "ns.qux#GetSomething", "ns.qux#GetSomethingOutput",
+                "ns.qux#GetSomethingOutput$widget1", "ns.qux#GetSomethingOutput$fooWidget", "ns.qux#Widget",
+                "ns.qux#FooWidget"));
+        assertThat(ids, not(containsInAnyOrder("ns.foo#MyService", "ns.foo#GetSomething", "ns.foo#GetSomethingOutput",
+                "ns.bar#Widget", "foo.example#Widget")));
+    }
+
     @Test
     public void throwsWhenServiceIsNotConfigured() {
         Model model = Model.assembler()

smithy-build/src/test/resources/software/amazon/smithy/build/transforms/flatten-namespaces-with-renames.json

@@ -0,0 +1,40 @@
+{
+  "smithy": "1.0",
+  "shapes": {
+    "ns.foo#MyService": {
+      "type": "service",
+      "version": "2017-02-11",
+      "operations": [
+        {
+          "target": "ns.foo#GetSomething"
+        }
+      ],
+      "rename": {
+        "foo.example#Widget": "FooWidget"
+      }
+    },
+    "ns.foo#GetSomething": {
+      "type": "operation",
+      "output": {
+        "target": "ns.foo#GetSomethingOutput"
+      }
+    },
+    "ns.foo#GetSomethingOutput": {
+      "type": "structure",
+      "members": {
+        "widget1": {
+          "target": "ns.bar#Widget"
+        },
+        "fooWidget": {
+          "target": "foo.example#Widget"
+        }
+      }
+    },
+    "ns.bar#Widget": {
+      "type": "structure"
+    },
+    "foo.example#Widget": {
+      "type": "structure"
+    }
+  }
+}