Additional files added to git

Author: Fahad Zubair

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/traits/SyntheticImplDisplayTrait.kt

@@ -0,0 +1,11 @@
+package software.amazon.smithy.rust.codegen.core.smithy.traits
+
+import software.amazon.smithy.model.node.Node
+import software.amazon.smithy.model.shapes.ShapeId
+import software.amazon.smithy.model.traits.AnnotationTrait
+
+class SyntheticImplDisplayTrait : AnnotationTrait(ID, Node.objectNode()) {
+    companion object {
+        val ID: ShapeId = ShapeId.from("software.amazon.smithy.rust.codegen.core.smithy.traits#syntheticImplDisplayTrait")
+    }
+}

codegen-core/src/main/kotlin/software/amazon/smithy/rust/codegen/core/smithy/transformers/AddSyntheticTraitForImplDisplay.kt

@@ -0,0 +1,73 @@
+package software.amazon.smithy.rust.codegen.core.smithy.transformers
+
+import software.amazon.smithy.model.Model
+import software.amazon.smithy.model.shapes.AbstractShapeBuilder
+import software.amazon.smithy.model.shapes.EnumShape
+import software.amazon.smithy.model.shapes.ListShape
+import software.amazon.smithy.model.shapes.MapShape
+import software.amazon.smithy.model.shapes.StructureShape
+import software.amazon.smithy.model.shapes.UnionShape
+import software.amazon.smithy.model.traits.ErrorTrait
+import software.amazon.smithy.model.transform.ModelTransformer
+import software.amazon.smithy.rust.codegen.core.smithy.DirectedWalker
+import software.amazon.smithy.rust.codegen.core.smithy.traits.SyntheticImplDisplayTrait
+import software.amazon.smithy.rust.codegen.core.util.UNREACHABLE
+import software.amazon.smithy.rust.codegen.core.util.getTrait
+import software.amazon.smithy.utils.ToSmithyBuilder
+
+/**
+ * Adds a synthetic trait to shapes that are reachable from error shapes to ensure they
+ * implement the `Display` trait in generated code.
+ *
+ * When a shape is annotated with `@error`, it needs to implement Rust's `Display` trait.
+ * If the error shape contains references to other structures, those structures also
+ * need to implement `Display` for proper error formatting.
+ */
+object AddSyntheticTraitForImplDisplay {
+    /**
+     * Transforms the model by adding [SyntheticImplDisplayTrait] to all shapes that are:
+     * 1. Reachable from an error shape
+     * 2. Not already marked with `@error`
+     * 3. Of a type that can implement `Display` (structure, list, union, or map)
+     *
+     * @param model The input model to transform
+     * @return The transformed model with synthetic traits added
+     */
+    fun transform(model: Model): Model {
+        val walker = DirectedWalker(model)
+
+        // Find all error shapes from operations.
+        val errorShapes =
+            model.operationShapes
+                .flatMap { it.errors }
+                .mapNotNull { model.expectShape(it).asStructureShape().orElse(null) }
+
+        // Get shapes reachable from error shapes that need Display impl.
+        val shapesNeedingDisplay =
+            errorShapes
+                .flatMap { walker.walkShapes(it) }
+                .filter {
+                    (it is StructureShape || it is ListShape || it is UnionShape || it is MapShape || it is EnumShape) &&
+                        it.getTrait<ErrorTrait>() == null
+                }
+
+        // Add synthetic trait to identified shapes.
+        val transformedShapes =
+            shapesNeedingDisplay.mapNotNull { shape ->
+                if (shape !is ToSmithyBuilder<*>) {
+                    UNREACHABLE("Shapes reachable from error shapes should be buildable")
+                    return@mapNotNull null
+                }
+
+                val builder = shape.toBuilder()
+                if (builder is AbstractShapeBuilder<*, *>) {
+                    builder.addTrait(SyntheticImplDisplayTrait()).build()
+                } else {
+                    UNREACHABLE("`impl Display` cannot be generated for ${shape.id}")
+                    null
+                }
+            }
+
+        return ModelTransformer.create().replaceShapes(model, transformedShapes)
+    }
+}

codegen-server/python/src/main/kotlin/software/amazon/smithy/rust/codegen/server/python/smithy/generators/PythonServerEnumGenerator.kt

@@ -59,20 +59,27 @@ class PythonConstrainedEnum(
         }
 
     private fun pyEnumName(context: EnumGeneratorContext): Writable =
-        writable {
-            rustBlock(
-                """
-                ##[getter]
-                pub fn name(&self) -> &str
-                """,
-            ) {
-                rustBlock("match self") {
-                    context.sortedMembers.forEach { member ->
-                        val memberName = member.name()?.name
-                        rust("""${context.enumName}::$memberName => ${memberName?.dq()},""")
+        // Only named enums have a `name` property. Do not generate `fn name` for
+        // unnamed enums.
+        if (context.enumTrait.hasNames()) {
+            writable {
+                rustBlock(
+                    """
+                    ##[getter]
+                    pub fn name(&self) -> &str
+                    """,
+                ) {
+                    rustBlock("match self") {
+                        context.sortedMembers.forEach { member ->
+                            val memberName = member.name()?.name
+                            check(memberName != null) { "${context.enumTrait} cannot have null members" }
+                            rust("""${context.enumName}::$memberName => ${memberName?.dq()},""")
+                        }
                     }
                 }
             }
+        } else {
+            writable {}
         }
 }
 

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

@@ -0,0 +1,16 @@
+package software.amazon.smithy.rust.codegen.server.smithy.generators
+
+import org.junit.jupiter.api.Test
+import software.amazon.smithy.rust.codegen.core.testutil.asSmithyModel
+import software.amazon.smithy.rust.codegen.server.smithy.testutil.serverIntegrationTest
+import java.io.File
+
+class ServerErrorReachableShapesDisplayTest {
+    @Test
+    fun `composite error shapes are compilable`() {
+        var sampleModel = File("../codegen-core/common-test-models/nested-error.smithy").readText().asSmithyModel()
+        serverIntegrationTest(sampleModel) { _, _ ->
+            // It should compile.
+        }
+    }
+}