bugfix: correct nullability semantics around generation and usage of struct members (#710)

Author: lucix-aws

.changes/da10a905-d84c-45bf-bc34-520ab90d9285.json

@@ -0,0 +1,5 @@
+{
+    "id": "da10a905-d84c-45bf-bc34-520ab90d9285",
+    "type": "bugfix",
+    "description": "Fix inconsistent nullability semantics when generating struct members."
+}

gradle.properties

@@ -24,7 +24,7 @@ jsoupVersion=1.14.3
 okHttpVersion=5.0.0-alpha.10
 
 # codegen
-smithyVersion=1.25.0
+smithyVersion=1.25.2
 smithyGradleVersion=0.6.0
 
 # testing/utility
@@ -46,4 +46,4 @@ kotlinLoggingVersion=2.1.21
 slf4jVersion=1.7.36
 
 # crt
-crtKotlinVersion=0.6.4
+crtKotlinVersion=0.6.4

smithy-kotlin-codegen/src/main/kotlin/software/amazon/smithy/kotlin/codegen/core/KotlinSymbolProvider.kt

@@ -170,7 +170,7 @@ class KotlinSymbolProvider(private val model: Model, private val settings: Kotli
         val targetShape =
             model.getShape(shape.target).orElseThrow { CodegenException("Shape not found: ${shape.target}") }
 
-        val targetSymbol = if (nullableIndex.isMemberNullable(shape, NullableIndex.CheckMode.CLIENT_ZERO_VALUE_V1)) {
+        val targetSymbol = if (nullableIndex.isMemberNullable(shape, NullableIndex.CheckMode.CLIENT_ZERO_VALUE_V1_NO_INPUT)) {
             toSymbol(targetShape).toBuilder().boxed().build()
         } else {
             toSymbol(targetShape)

smithy-kotlin-codegen/src/main/kotlin/software/amazon/smithy/kotlin/codegen/rendering/StructureGenerator.kt

@@ -9,7 +9,6 @@ import software.amazon.smithy.codegen.core.Symbol
 import software.amazon.smithy.kotlin.codegen.core.*
 import software.amazon.smithy.kotlin.codegen.lang.KotlinTypes
 import software.amazon.smithy.kotlin.codegen.model.*
-import software.amazon.smithy.model.knowledge.NullableIndex
 import software.amazon.smithy.model.shapes.*
 import software.amazon.smithy.model.traits.ErrorTrait
 import software.amazon.smithy.model.traits.HttpLabelTrait
@@ -28,7 +27,6 @@ class StructureGenerator(
     private val symbolProvider = ctx.symbolProvider
     private val model = ctx.model
     private val symbol = ctx.symbolProvider.toSymbol(ctx.shape)
-    private val nullableIndex = NullableIndex(ctx.model)
 
     fun render() {
         writer.renderDocumentation(shape)
@@ -148,7 +146,7 @@ class StructureGenerator(
     // Return the appropriate hashCode fragment based on ShapeID of member target.
     private fun selectHashFunctionForShape(member: MemberShape): String {
         val targetShape = model.expectShape(member.target)
-        val isNullable = nullableIndex.isMemberNullable(member, NullableIndex.CheckMode.CLIENT_ZERO_VALUE_V1_NO_INPUT)
+        val isNullable = memberNameSymbolIndex[member]!!.second.isBoxed
         return when (targetShape.type) {
             ShapeType.INTEGER ->
                 when (isNullable) {

smithy-kotlin-codegen/src/test/kotlin/software/amazon/smithy/kotlin/codegen/rendering/StructureGeneratorTest.kt

@@ -644,6 +644,36 @@ class StructureGeneratorTest {
         contents.shouldContainOnlyOnceWithDiff(expectedEqualsContent)
         contents.shouldContainOnlyOnceWithDiff(expectedHashCodeContent)
     }
+
+    @Test
+    fun testNullableReferences() {
+        val model = """
+            structure Struct {
+                aInt: Integer
+                @default(0)
+                bInt: Integer
+            }
+        """
+            .trimIndent()
+            .prependNamespaceAndService(version = "2.0")
+            .toSmithyModel()
+
+        val provider: SymbolProvider = KotlinCodegenPlugin.createSymbolProvider(model)
+        val writer = KotlinWriter(TestModelDefault.NAMESPACE)
+        val struct = model.expectShape<StructureShape>("com.test#Struct")
+        val renderingCtx = RenderingContext(writer, struct, model, provider, model.defaultSettings())
+        StructureGenerator(renderingCtx).render()
+
+        val generated = writer.toString()
+        val expected = """
+            override fun hashCode(): kotlin.Int {
+                var result = aInt ?: 0
+                result = 31 * result + (bInt)
+                return result
+            }
+        """.formatForTest()
+        generated.shouldContainOnlyOnceWithDiff(expected)
+    }
 }
 
 private fun String?.indent(indentation: String = "    "): String? = if (this == null) null else "$indentation$this"