Flatten and remove mixins from code generation

CHANGELOG.next.toml

@@ -73,7 +73,6 @@ references = ["smithy-rs#1603", "aws-sdk-rust#586"]
 meta = { "breaking" = true, "tada" = false, "bug" = false, "target" = "client" }
 author = "jdisanti"
 
-
 [[aws-sdk-rust]]
 message = """
 Implemented customizable operations per [RFC-0017](https://awslabs.github.io/smithy-rs/design/rfcs/rfc0017_customizable_client_operations.html).
@@ -169,3 +168,9 @@ let response = client.some_operation()
 references = ["smithy-rs#1647", "smithy-rs#1112"]
 meta = { "breaking" = false, "tada" = true, "bug" = false, "target" = "client"}
 author = "Velfi"
+
+[[smithy-rs]]
+message = "Smithy IDL v2 mixins are now supported"
+references = ["smithy-rs#1680"]
+meta = { "breaking" = false, "tada" = false, "bug" = false, "target" = "all"}
+author = "ogudavid"

codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/ServerCodegenVisitor.kt

@@ -103,6 +103,8 @@ open class ServerCodegenVisitor(
      */
     protected fun baselineTransform(model: Model) =
         model
+            // Flattens mixins out of the model and removes them from the model
+            .let { ModelTransformer.create().flattenAndRemoveMixins(it) }
             // Add errors attached at the service level to the models
             .let { ModelTransformer.create().copyServiceErrorsToOperations(it, settings.getService(it)) }
             // Add `Box<T>` to recursive shapes as necessary
@@ -114,6 +116,12 @@ open class ServerCodegenVisitor(
             // Normalize event stream operations
             .let(EventStreamNormalizer::transform)
 
+    /**
+     * Exposure purely for unit test purposes.
+     */
+    internal fun baselineTransformInternalTest(model: Model) =
+        baselineTransform(model)
+
     /**
      * Execute code generation
      *

codegen-server/src/test/kotlin/software/amazon/smithy/rust/codegen/server/smithy/ServerCodegenVisitorTest.kt

@@ -0,0 +1,57 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.rust.codegen.server.smithy
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.Test
+import software.amazon.smithy.model.shapes.ShapeId
+import software.amazon.smithy.rust.codegen.server.smithy.customizations.ServerRequiredCustomizations
+import software.amazon.smithy.rust.codegen.smithy.ServerCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.customize.CombinedCodegenDecorator
+import software.amazon.smithy.rust.codegen.testutil.asSmithyModel
+import software.amazon.smithy.rust.codegen.testutil.generatePluginContext
+import kotlin.io.path.createDirectory
+import kotlin.io.path.writeText
+
+class ServerCodegenVisitorTest {
+    @Test
+    fun `baseline transform verify mixins removed`() {
+        val model = """
+            namespace com.example
+
+            use aws.protocols#awsJson1_0
+
+            @awsJson1_0
+            @aws.api#service(sdkId: "Test", endpointPrefix: "differentPrefix")
+            service Example {
+                operations: [ BasicOperation ]
+            }
+
+            operation BasicOperation {
+                input: Shape
+            }
+
+            @mixin
+            structure SimpleMixin {
+                name: String
+            }
+
+            structure Shape with [
+                SimpleMixin
+            ] {
+                greeting: String
+            }
+        """.asSmithyModel(smithyVersion = "2.0")
+        val (ctx, testDir) = generatePluginContext(model)
+        testDir.resolve("src").createDirectory()
+        testDir.resolve("src/main.rs").writeText("fn main() {}")
+        val codegenDecorator: CombinedCodegenDecorator<ServerCodegenContext> =
+            CombinedCodegenDecorator.fromClasspath(ctx, ServerRequiredCustomizations())
+        val visitor = ServerCodegenVisitor(ctx, codegenDecorator)
+        val baselineModel = visitor.baselineTransformInternalTest(model)
+        baselineModel.getShapesWithTrait(ShapeId.from("smithy.api#mixin")).isEmpty() shouldBe true
+    }
+}

codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/CodegenVisitor.kt

@@ -86,8 +86,10 @@ class CodegenVisitor(context: PluginContext, private val codegenDecorator: RustC
      * Base model transformation applied to all services
      * See below for details.
      */
-    private fun baselineTransform(model: Model) =
+    internal fun baselineTransform(model: Model) =
         model
+            // Flattens mixins out of the model and removes them from the model
+            .let { ModelTransformer.create().flattenAndRemoveMixins(it) }
             // Add errors attached at the service level to the models
             .let { ModelTransformer.create().copyServiceErrorsToOperations(it, settings.getService(it)) }
             // Add `Box<T>` to recursive shapes as necessary

codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/testutil/TestHelpers.kt

@@ -88,8 +88,8 @@ fun testCodegenContext(
 )
 
 private const val SmithyVersion = "1.0"
-fun String.asSmithyModel(sourceLocation: String? = null): Model {
-    val processed = letIf(!this.startsWith("\$version")) { "\$version: ${SmithyVersion.dq()}\n$it" }
+fun String.asSmithyModel(sourceLocation: String? = null, smithyVersion: String = SmithyVersion): Model {
+    val processed = letIf(!this.startsWith("\$version")) { "\$version: ${smithyVersion.dq()}\n$it" }
     return Model.assembler().discoverModels().addUnparsedModel(sourceLocation ?: "test.smithy", processed).assemble()
         .unwrap()
 }

codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/CodegenVisitorTest.kt

@@ -0,0 +1,65 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.rust.codegen.smithy
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.Test
+import software.amazon.smithy.model.shapes.ShapeId
+import software.amazon.smithy.rust.codegen.smithy.customizations.ClientCustomizations
+import software.amazon.smithy.rust.codegen.smithy.customize.CombinedCodegenDecorator
+import software.amazon.smithy.rust.codegen.smithy.customize.NoOpEventStreamSigningDecorator
+import software.amazon.smithy.rust.codegen.smithy.customize.RequiredCustomizations
+import software.amazon.smithy.rust.codegen.smithy.generators.client.FluentClientDecorator
+import software.amazon.smithy.rust.codegen.testutil.asSmithyModel
+import software.amazon.smithy.rust.codegen.testutil.generatePluginContext
+import kotlin.io.path.createDirectory
+import kotlin.io.path.writeText
+
+class CodegenVisitorTest {
+    @Test
+    fun `baseline transform verify mixins removed`() {
+        val model = """
+            namespace com.example
+
+            use aws.protocols#awsJson1_0
+
+            @awsJson1_0
+            @aws.api#service(sdkId: "Test", endpointPrefix: "differentPrefix")
+            service Example {
+                operations: [ BasicOperation ]
+            }
+
+            operation BasicOperation {
+                input: Shape
+            }
+
+            @mixin
+            structure SimpleMixin {
+                name: String
+            }
+
+            structure Shape with [
+                SimpleMixin
+            ] {
+                greeting: String
+            }
+        """.asSmithyModel(smithyVersion = "2.0")
+        val (ctx, testDir) = generatePluginContext(model)
+        testDir.resolve("src").createDirectory()
+        testDir.resolve("src/main.rs").writeText("fn main() {}")
+        val codegenDecorator =
+            CombinedCodegenDecorator.fromClasspath(
+                ctx,
+                ClientCustomizations(),
+                RequiredCustomizations(),
+                FluentClientDecorator(),
+                NoOpEventStreamSigningDecorator(),
+            )
+        val visitor = CodegenVisitor(ctx, codegenDecorator)
+        val baselineModel = visitor.baselineTransform(model)
+        baselineModel.getShapesWithTrait(ShapeId.from("smithy.api#mixin")).isEmpty() shouldBe true
+    }
+}