Upstream KSP implementation (#1393)

2025-10-18 23:49:21 +08:00 · 2021-10-16 01:52:04 -04:00
parent de8bbf12f5
commit 2db351f8ed
25 changed files with 2164 additions and 131 deletions
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -4,6 +4,7 @@ on: [push, pull_request]

 jobs:
  build:
+    name: 'Java ${{ matrix.java-version }} | KSP ${{ matrix.use-ksp }}'
    runs-on: ubuntu-latest

    strategy:
@@ -11,6 +12,7 @@ jobs:
      matrix:
        java-version:
          - 16
+        use-ksp: [ true, false ]

    steps:
      - name: Checkout
@@ -36,7 +38,7 @@ jobs:
          java-version: ${{ matrix.java-version }}

      - name: Test
-        run: ./gradlew build check --stacktrace
+        run: ./gradlew build check --stacktrace -PuseKsp=${{ matrix.use-ksp }}

      - name: Publish (default branch only)
        if: github.repository == 'square/moshi' && github.ref == 'refs/heads/master' && matrix.java-version == '16'
--- a/gradle.properties
+++ b/gradle.properties
@@ -16,34 +16,32 @@

 # For Dokka https://github.com/Kotlin/dokka/issues/1405
 org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8 \
-  --add-opens=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED \
-  --add-opens=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
-  --add-opens=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED \
-  --add-opens=jdk.compiler/com.sun.tools.javac.jvm=ALL-UNNAMED  \
-  --add-opens=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED \
  --add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.jvm=ALL-UNNAMED  \
+  --add-opens=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED \
  --add-opens=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+  --add-opens=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED

-# TODO move this to DSL in Kotlin 1.5.30 https://youtrack.jetbrains.com/issue/KT-44266
 kotlin.daemon.jvmargs=-Dfile.encoding=UTF-8 \
-  --add-opens=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED \
-  --add-opens=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
-  --add-opens=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED \
-  --add-opens=jdk.compiler/com.sun.tools.javac.jvm=ALL-UNNAMED  \
-  --add-opens=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED \
  --add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.jvm=ALL-UNNAMED  \
+  --add-opens=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
+  --add-opens=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED \
  --add-opens=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
-  --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+  --add-opens=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED

+# Kapt doesn't read the above jvm args when workers are used
+# https://youtrack.jetbrains.com/issue/KT-48402
+kapt.use.worker.api=false
 kapt.include.compile.classpath=false

 GROUP=com.squareup.moshi
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -15,16 +15,17 @@
 [versions]
 autoService = "1.0"
 gjf = "1.11.0"
-incap = "0.3"
 jvmTarget = "1.8"
-kotlin = "1.5.21"
-kotlinCompileTesting = "1.4.3"
-kotlinpoet = "1.10.0"
+kotlin = "1.5.31"
+kotlinCompileTesting = "1.4.4"
+kotlinpoet = "1.10.1"
+ksp = "1.5.31-1.0.0"
 ktlint = "0.41.0"

 [plugins]
-dokka = { id = "org.jetbrains.dokka", version = "1.5.0" }
+dokka = { id = "org.jetbrains.dokka", version = "1.5.30" }
 japicmp = { id = "me.champeau.gradle.japicmp", version = "0.2.9" }
+ksp = { id = "com.google.devtools.ksp", version.ref = "ksp" }
 mavenPublish = { id = "com.vanniktech.maven.publish", version = "0.17.0" }
 mavenShadow = { id = "com.github.johnrengelman.shadow", version = "7.0.0" }
 spotless = { id = "com.diffplug.spotless", version = "5.14.2" }
@@ -33,20 +34,22 @@ spotless = { id = "com.diffplug.spotless", version = "5.14.2" }
 asm = "org.ow2.asm:asm:9.2"
 autoCommon = "com.google.auto:auto-common:1.1"
 autoService = { module = "com.google.auto.service:auto-service-annotations", version.ref = "autoService" }
-autoService-processor = { module = "com.google.auto.service:auto-service", version.ref = "autoService" }
-guava = { module = "com.google.guava:guava", version = "30.1.1-jre" }
-incap = { module = "net.ltgt.gradle.incap:incap", version.ref = "incap" }
-incap-processor = { module = "net.ltgt.gradle.incap:incap-processor", version.ref = "incap" }
+autoService-ksp = "dev.zacsweers.autoservice:auto-service-ksp:1.0.0"
+guava = "com.google.guava:guava:30.1.1-jre"
 jsr305 = "com.google.code.findbugs:jsr305:3.0.2"
 kotlin-compilerEmbeddable = { module = "org.jetbrains.kotlin:kotlin-compiler-embeddable", version.ref = "kotlin" }
 kotlin-reflect = { module = "org.jetbrains.kotlin:kotlin-reflect", version.ref = "kotlin" }
 kotlinpoet = { module = "com.squareup:kotlinpoet", version.ref = "kotlinpoet" }
 kotlinpoet-metadata = { module = "com.squareup:kotlinpoet-metadata", version.ref = "kotlinpoet" }
+kotlinpoet-ksp = { module = "com.squareup:kotlinpoet-ksp", version.ref = "kotlinpoet" }
 kotlinxMetadata = "org.jetbrains.kotlinx:kotlinx-metadata-jvm:0.3.0"
+ksp = { module = "com.google.devtools.ksp:symbol-processing", version.ref = "ksp" }
+ksp-api = { module = "com.google.devtools.ksp:symbol-processing-api", version.ref = "ksp" }
 okio = "com.squareup.okio:okio:2.10.0"

 # Test libs
 assertj = "org.assertj:assertj-core:3.11.1"
 junit = "junit:junit:4.13.2"
 kotlinCompileTesting = { module = "com.github.tschuchortdev:kotlin-compile-testing", version.ref = "kotlinCompileTesting" }
+kotlinCompileTesting-ksp = { module = "com.github.tschuchortdev:kotlin-compile-testing-ksp", version.ref ="kotlinCompileTesting" }
 truth = "com.google.truth:truth:1.1.3"
--- a/kotlin/codegen/build.gradle.kts
+++ b/kotlin/codegen/build.gradle.kts
@@ -20,7 +20,7 @@ import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

 plugins {
  kotlin("jvm")
-  kotlin("kapt")
+  alias(libs.plugins.ksp)
  id("com.vanniktech.maven.publish")
  alias(libs.plugins.mavenShadow)
 }
@@ -31,12 +31,12 @@ tasks.withType<KotlinCompile>().configureEach {
    freeCompilerArgs += listOf(
      "-Xopt-in=kotlin.RequiresOptIn",
      "-Xopt-in=com.squareup.kotlinpoet.metadata.KotlinPoetMetadataPreview",
+      "-Xopt-in=com.squareup.kotlinpoet.ksp.KotlinPoetKspPreview",
    )
  }
 }

 tasks.withType<Test>().configureEach {
-  // For kapt to work with kotlin-compile-testing
  jvmArgs(
    "--add-opens=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED",
    "--add-opens=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED",
@@ -47,17 +47,15 @@ tasks.withType<Test>().configureEach {
    "--add-opens=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED",
    "--add-opens=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED",
    "--add-opens=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED",
-    "--add-opens=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED",
+    "--add-opens=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED"
  )
 }

 val shade: Configuration = configurations.maybeCreate("compileShaded")
 configurations.getByName("compileOnly").extendsFrom(shade)
 dependencies {
-  // Use `api` because kapt will not resolve `runtime` dependencies without it, only `compile`
-  // https://youtrack.jetbrains.com/issue/KT-41702
-  api(project(":moshi"))
-  api(kotlin("reflect"))
+  implementation(project(":moshi"))
+  implementation(kotlin("reflect"))
  shade(libs.kotlinxMetadata) {
    exclude(group = "org.jetbrains.kotlin", module = "kotlin-stdlib")
  }
@@ -67,16 +65,30 @@ dependencies {
    exclude(group = "com.squareup", module = "kotlinpoet")
    exclude(group = "com.google.guava")
  }
-  api(libs.guava)
-  api(libs.asm)
+  shade(libs.kotlinpoet.ksp) {
+    exclude(group = "org.jetbrains.kotlin")
+    exclude(group = "com.squareup", module = "kotlinpoet")
+  }
+  implementation(libs.guava)
+  implementation(libs.asm)

-  api(libs.autoService)
-  kapt(libs.autoService.processor)
-  api(libs.incap)
-  kapt(libs.incap.processor)
+  implementation(libs.autoService)
+  ksp(libs.autoService.ksp)
+
+  // KSP deps
+  compileOnly(libs.ksp)
+  compileOnly(libs.ksp.api)
+  compileOnly(libs.kotlin.compilerEmbeddable)
+  // Always force the latest KSP version to match the one we're compiling against
+  testImplementation(libs.ksp)
+  testImplementation(libs.kotlin.compilerEmbeddable)
+  testImplementation(libs.kotlinCompileTesting.ksp)

  // Copy these again as they're not automatically included since they're shaded
+  testImplementation(project(":moshi"))
+  testImplementation(kotlin("reflect"))
  testImplementation(libs.kotlinpoet.metadata)
+  testImplementation(libs.kotlinpoet.ksp)
  testImplementation(libs.junit)
  testImplementation(libs.truth)
  testImplementation(libs.kotlinCompileTesting)
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/Options.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/Options.kt
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.api
+
+import com.squareup.kotlinpoet.ClassName
+
+internal object Options {
+  /**
+   * This processing option can be specified to have a `@Generated` annotation
+   * included in the generated code. It is not encouraged unless you need it for static analysis
+   * reasons and not enabled by default.
+   *
+   * Note that this can only be one of the following values:
+   *   * `"javax.annotation.processing.Generated"` (JRE 9+)
+   *   * `"javax.annotation.Generated"` (JRE <9)
+   */
+  const val OPTION_GENERATED: String = "moshi.generated"
+
+  /**
+   * This boolean processing option can disable proguard rule generation.
+   * Normally, this is not recommended unless end-users build their own JsonAdapter look-up tool.
+   * This is enabled by default.
+   */
+  const val OPTION_GENERATE_PROGUARD_RULES: String = "moshi.generateProguardRules"
+
+  val POSSIBLE_GENERATED_NAMES = arrayOf(
+    ClassName("javax.annotation.processing", "Generated"),
+    ClassName("javax.annotation", "Generated")
+  ).associateBy { it.canonicalName }
+}
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/ProguardRules.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/ProguardRules.kt
@@ -16,9 +16,6 @@
 package com.squareup.moshi.kotlin.codegen.api

 import com.squareup.kotlinpoet.ClassName
-import javax.annotation.processing.Filer
-import javax.lang.model.element.Element
-import javax.tools.StandardLocation

 /**
 * Represents a proguard configuration for a given spec. This covers three main areas:
@@ -42,16 +39,11 @@ internal data class ProguardConfig(
  val targetConstructorParams: List<String>,
  val qualifierProperties: Set<QualifierAdapterProperty>
 ) {
-  private val outputFile = "META-INF/proguard/moshi-${targetClass.canonicalName}.pro"
-
-  /** Writes this to `filer`. */
-  fun writeTo(filer: Filer, vararg originatingElements: Element) {
-    filer.createResource(StandardLocation.CLASS_OUTPUT, "", outputFile, *originatingElements)
-      .openWriter()
-      .use(::writeTo)
+  fun outputFilePathWithoutExtension(canonicalName: String): String {
+    return "META-INF/proguard/moshi-$canonicalName"
  }

-  private fun writeTo(out: Appendable): Unit = out.run {
+  fun writeTo(out: Appendable): Unit = out.run {
    //
    // -if class {the target class}
    // -keepnames class {the target class}
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/kotlintypes.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/kotlintypes.kt
@@ -217,8 +217,12 @@ internal fun List<TypeName>.toTypeVariableResolver(
    // replacement later that may add bounds referencing this.
    val id = typeVar.name
    parametersMap[id] = TypeVariableName(id)
+  }
+
+  for (typeVar in this) {
+    check(typeVar is TypeVariableName)
    // Now replace it with the full version.
-    parametersMap[id] = typeVar.deepCopy(null) { it.stripTypeVarVariance(resolver) }
+    parametersMap[typeVar.name] = typeVar.deepCopy(null) { it.stripTypeVarVariance(resolver) }
  }

  return resolver
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/typeAliasUnwrapping.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/api/typeAliasUnwrapping.kt
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.api
+
+import com.squareup.kotlinpoet.AnnotationSpec
+import com.squareup.kotlinpoet.ClassName
+import com.squareup.kotlinpoet.LambdaTypeName
+import com.squareup.kotlinpoet.ParameterizedTypeName
+import com.squareup.kotlinpoet.TypeName
+import com.squareup.kotlinpoet.TypeVariableName
+import com.squareup.kotlinpoet.WildcardTypeName
+import com.squareup.kotlinpoet.tag
+import com.squareup.kotlinpoet.tags.TypeAliasTag
+import java.util.TreeSet
+
+internal fun TypeName.unwrapTypeAliasReal(): TypeName {
+  return tag<TypeAliasTag>()?.abbreviatedType?.let { unwrappedType ->
+    // If any type is nullable, then the whole thing is nullable
+    var isAnyNullable = isNullable
+    // Keep track of all annotations across type levels. Sort them too for consistency.
+    val runningAnnotations = TreeSet<AnnotationSpec>(compareBy { it.toString() }).apply {
+      addAll(annotations)
+    }
+    val nestedUnwrappedType = unwrappedType.unwrapTypeAlias()
+    runningAnnotations.addAll(nestedUnwrappedType.annotations)
+    isAnyNullable = isAnyNullable || nestedUnwrappedType.isNullable
+    nestedUnwrappedType.copy(nullable = isAnyNullable, annotations = runningAnnotations.toList())
+  } ?: this
+}
+
+internal fun TypeName.unwrapTypeAlias(): TypeName {
+  return when (this) {
+    is ClassName -> unwrapTypeAliasReal()
+    is ParameterizedTypeName -> {
+      if (TypeAliasTag::class in tags) {
+        unwrapTypeAliasReal()
+      } else {
+        deepCopy(TypeName::unwrapTypeAlias)
+      }
+    }
+    is TypeVariableName -> {
+      if (TypeAliasTag::class in tags) {
+        unwrapTypeAliasReal()
+      } else {
+        deepCopy(transform = TypeName::unwrapTypeAlias)
+      }
+    }
+    is WildcardTypeName -> {
+      if (TypeAliasTag::class in tags) {
+        unwrapTypeAliasReal()
+      } else {
+        deepCopy(TypeName::unwrapTypeAlias)
+      }
+    }
+    is LambdaTypeName -> {
+      if (TypeAliasTag::class in tags) {
+        unwrapTypeAliasReal()
+      } else {
+        deepCopy(TypeName::unwrapTypeAlias)
+      }
+    }
+    else -> throw UnsupportedOperationException("Type '${javaClass.simpleName}' is illegal. Only classes, parameterized types, wildcard types, or type variables are allowed.")
+  }
+}
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/apt/JsonClassCodegenProcessor.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/apt/JsonClassCodegenProcessor.kt
@@ -21,9 +21,11 @@ import com.squareup.kotlinpoet.ClassName
 import com.squareup.kotlinpoet.metadata.classinspectors.ElementsClassInspector
 import com.squareup.moshi.JsonClass
 import com.squareup.moshi.kotlin.codegen.api.AdapterGenerator
+import com.squareup.moshi.kotlin.codegen.api.Options.OPTION_GENERATED
+import com.squareup.moshi.kotlin.codegen.api.Options.OPTION_GENERATE_PROGUARD_RULES
+import com.squareup.moshi.kotlin.codegen.api.Options.POSSIBLE_GENERATED_NAMES
+import com.squareup.moshi.kotlin.codegen.api.ProguardConfig
 import com.squareup.moshi.kotlin.codegen.api.PropertyGenerator
-import net.ltgt.gradle.incap.IncrementalAnnotationProcessor
-import net.ltgt.gradle.incap.IncrementalAnnotationProcessorType.ISOLATING
 import javax.annotation.processing.AbstractProcessor
 import javax.annotation.processing.Filer
 import javax.annotation.processing.Messager
@@ -31,10 +33,12 @@ import javax.annotation.processing.ProcessingEnvironment
 import javax.annotation.processing.Processor
 import javax.annotation.processing.RoundEnvironment
 import javax.lang.model.SourceVersion
+import javax.lang.model.element.Element
 import javax.lang.model.element.TypeElement
 import javax.lang.model.util.Elements
 import javax.lang.model.util.Types
 import javax.tools.Diagnostic
+import javax.tools.StandardLocation

 /**
 * An annotation processor that reads Kotlin data classes and generates Moshi JsonAdapters for them.
@@ -45,34 +49,8 @@ import javax.tools.Diagnostic
 * adapter will also be internal).
 */
@AutoService(Processor::class)
-@IncrementalAnnotationProcessor(ISOLATING)
 public class JsonClassCodegenProcessor : AbstractProcessor() {

-  public companion object {
-    /**
-     * This annotation processing argument can be specified to have a `@Generated` annotation
-     * included in the generated code. It is not encouraged unless you need it for static analysis
-     * reasons and not enabled by default.
-     *
-     * Note that this can only be one of the following values:
-     *   * `"javax.annotation.processing.Generated"` (JRE 9+)
-     *   * `"javax.annotation.Generated"` (JRE <9)
-     */
-    public const val OPTION_GENERATED: String = "moshi.generated"
-
-    /**
-     * This boolean processing option can control proguard rule generation.
-     * Normally, this is not recommended unless end-users build their own JsonAdapter look-up tool.
-     * This is enabled by default.
-     */
-    public const val OPTION_GENERATE_PROGUARD_RULES: String = "moshi.generateProguardRules"
-
-    private val POSSIBLE_GENERATED_NAMES = arrayOf(
-      ClassName("javax.annotation.processing", "Generated"),
-      ClassName("javax.annotation", "Generated")
-    ).associateBy { it.canonicalName }
-  }
-
  private lateinit var types: Types
  private lateinit var elements: Elements
  private lateinit var filer: Filer
@@ -190,3 +168,10 @@ public class JsonClassCodegenProcessor : AbstractProcessor() {
    return AdapterGenerator(type, sortedProperties)
  }
 }
+
+/** Writes this config to a [filer]. */
+private fun ProguardConfig.writeTo(filer: Filer, vararg originatingElements: Element) {
+  filer.createResource(StandardLocation.CLASS_OUTPUT, "", "${outputFilePathWithoutExtension(targetClass.canonicalName)}.pro", *originatingElements)
+    .openWriter()
+    .use(::writeTo)
+}
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/apt/metadata.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/apt/metadata.kt
@@ -19,12 +19,10 @@ import com.squareup.kotlinpoet.AnnotationSpec
 import com.squareup.kotlinpoet.ClassName
 import com.squareup.kotlinpoet.DelicateKotlinPoetApi
 import com.squareup.kotlinpoet.KModifier
-import com.squareup.kotlinpoet.LambdaTypeName
 import com.squareup.kotlinpoet.ParameterizedTypeName
 import com.squareup.kotlinpoet.TypeName
 import com.squareup.kotlinpoet.TypeSpec
 import com.squareup.kotlinpoet.TypeVariableName
-import com.squareup.kotlinpoet.WildcardTypeName
 import com.squareup.kotlinpoet.asClassName
 import com.squareup.kotlinpoet.asTypeName
 import com.squareup.kotlinpoet.metadata.KotlinPoetMetadataPreview
@@ -37,7 +35,6 @@ import com.squareup.kotlinpoet.metadata.isLocal
 import com.squareup.kotlinpoet.metadata.isPublic
 import com.squareup.kotlinpoet.metadata.isSealed
 import com.squareup.kotlinpoet.tag
-import com.squareup.kotlinpoet.tags.TypeAliasTag
 import com.squareup.moshi.Json
 import com.squareup.moshi.JsonQualifier
 import com.squareup.moshi.kotlin.codegen.api.DelegateKey
@@ -46,15 +43,14 @@ import com.squareup.moshi.kotlin.codegen.api.TargetConstructor
 import com.squareup.moshi.kotlin.codegen.api.TargetParameter
 import com.squareup.moshi.kotlin.codegen.api.TargetProperty
 import com.squareup.moshi.kotlin.codegen.api.TargetType
-import com.squareup.moshi.kotlin.codegen.api.deepCopy
 import com.squareup.moshi.kotlin.codegen.api.rawType
+import com.squareup.moshi.kotlin.codegen.api.unwrapTypeAlias
 import kotlinx.metadata.KmConstructor
 import kotlinx.metadata.jvm.signature
 import java.lang.annotation.ElementType
 import java.lang.annotation.Retention
 import java.lang.annotation.RetentionPolicy
 import java.lang.annotation.Target
-import java.util.TreeSet
 import javax.annotation.processing.Messager
 import javax.lang.model.element.AnnotationMirror
 import javax.lang.model.element.Element
@@ -516,30 +512,6 @@ private fun String.escapeDollarSigns(): String {
  return replace("\$", "\${\'\$\'}")
 }

-internal fun TypeName.unwrapTypeAlias(): TypeName {
-  return when (this) {
-    is ClassName -> {
-      tag<TypeAliasTag>()?.abbreviatedType?.let { unwrappedType ->
-        // If any type is nullable, then the whole thing is nullable
-        var isAnyNullable = isNullable
-        // Keep track of all annotations across type levels. Sort them too for consistency.
-        val runningAnnotations = TreeSet<AnnotationSpec>(compareBy { it.toString() }).apply {
-          addAll(annotations)
-        }
-        val nestedUnwrappedType = unwrappedType.unwrapTypeAlias()
-        runningAnnotations.addAll(nestedUnwrappedType.annotations)
-        isAnyNullable = isAnyNullable || nestedUnwrappedType.isNullable
-        nestedUnwrappedType.copy(nullable = isAnyNullable, annotations = runningAnnotations.toList())
-      } ?: this
-    }
-    is ParameterizedTypeName -> deepCopy(TypeName::unwrapTypeAlias)
-    is TypeVariableName -> deepCopy(transform = TypeName::unwrapTypeAlias)
-    is WildcardTypeName -> deepCopy(TypeName::unwrapTypeAlias)
-    is LambdaTypeName -> deepCopy(TypeName::unwrapTypeAlias)
-    else -> throw UnsupportedOperationException("Type '${javaClass.simpleName}' is illegal. Only classes, parameterized types, wildcard types, or type variables are allowed.")
-  }
-}
-
 internal val TypeElement.metadata: Metadata
  get() {
    return getAnnotation(Metadata::class.java)
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/AppliedType.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/AppliedType.kt
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.ksp
+
+import com.google.devtools.ksp.getAllSuperTypes
+import com.google.devtools.ksp.processing.Resolver
+import com.google.devtools.ksp.symbol.ClassKind.CLASS
+import com.google.devtools.ksp.symbol.KSClassDeclaration
+import com.squareup.kotlinpoet.ANY
+import com.squareup.kotlinpoet.TypeName
+import com.squareup.kotlinpoet.asClassName
+import com.squareup.kotlinpoet.ksp.toClassName
+
+private val OBJECT_CLASS = java.lang.Object::class.asClassName()
+
+/**
+ * A concrete type like `List<String>` with enough information to know how to resolve its type
+ * variables.
+ */
+internal class AppliedType private constructor(
+  val type: KSClassDeclaration,
+  val typeName: TypeName = type.toClassName()
+) {
+
+  /** Returns all supertypes of this, recursively. Includes both interface and class supertypes. */
+  fun supertypes(
+    resolver: Resolver,
+  ): LinkedHashSet<AppliedType> {
+    val result: LinkedHashSet<AppliedType> = LinkedHashSet()
+    result.add(this)
+    for (supertype in type.getAllSuperTypes()) {
+      val decl = supertype.declaration
+      check(decl is KSClassDeclaration)
+      if (decl.classKind != CLASS) {
+        // Don't load properties for interface types.
+        continue
+      }
+      val qualifiedName = decl.qualifiedName
+      val superTypeKsClass = resolver.getClassDeclarationByName(qualifiedName!!)!!
+      val typeName = decl.toClassName()
+      if (typeName == ANY || typeName == OBJECT_CLASS) {
+        // Don't load properties for kotlin.Any/java.lang.Object.
+        continue
+      }
+      result.add(AppliedType(superTypeKsClass, typeName))
+    }
+    return result
+  }
+
+  override fun toString() = type.qualifiedName!!.asString()
+
+  companion object {
+    fun get(type: KSClassDeclaration): AppliedType {
+      return AppliedType(type)
+    }
+  }
+}
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/JsonClassSymbolProcessorProvider.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/JsonClassSymbolProcessorProvider.kt
@@ -0,0 +1,167 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.ksp
+
+import com.google.auto.service.AutoService
+import com.google.devtools.ksp.processing.CodeGenerator
+import com.google.devtools.ksp.processing.Dependencies
+import com.google.devtools.ksp.processing.KSPLogger
+import com.google.devtools.ksp.processing.Resolver
+import com.google.devtools.ksp.processing.SymbolProcessor
+import com.google.devtools.ksp.processing.SymbolProcessorEnvironment
+import com.google.devtools.ksp.processing.SymbolProcessorProvider
+import com.google.devtools.ksp.symbol.KSAnnotated
+import com.google.devtools.ksp.symbol.KSDeclaration
+import com.google.devtools.ksp.symbol.KSFile
+import com.squareup.kotlinpoet.AnnotationSpec
+import com.squareup.kotlinpoet.ksp.addOriginatingKSFile
+import com.squareup.kotlinpoet.ksp.toClassName
+import com.squareup.kotlinpoet.ksp.writeTo
+import com.squareup.moshi.JsonClass
+import com.squareup.moshi.kotlin.codegen.api.AdapterGenerator
+import com.squareup.moshi.kotlin.codegen.api.Options.OPTION_GENERATED
+import com.squareup.moshi.kotlin.codegen.api.Options.OPTION_GENERATE_PROGUARD_RULES
+import com.squareup.moshi.kotlin.codegen.api.Options.POSSIBLE_GENERATED_NAMES
+import com.squareup.moshi.kotlin.codegen.api.ProguardConfig
+import com.squareup.moshi.kotlin.codegen.api.PropertyGenerator
+import java.io.OutputStreamWriter
+import java.nio.charset.StandardCharsets
+
+@AutoService(SymbolProcessorProvider::class)
+public class JsonClassSymbolProcessorProvider : SymbolProcessorProvider {
+  override fun create(environment: SymbolProcessorEnvironment): SymbolProcessor {
+    return JsonClassSymbolProcessor(environment)
+  }
+}
+
+private class JsonClassSymbolProcessor(
+  environment: SymbolProcessorEnvironment
+) : SymbolProcessor {
+
+  private companion object {
+    val JSON_CLASS_NAME = JsonClass::class.qualifiedName!!
+  }
+
+  private val codeGenerator = environment.codeGenerator
+  private val logger = environment.logger
+  private val generatedOption = environment.options[OPTION_GENERATED]?.also {
+    logger.check(it in POSSIBLE_GENERATED_NAMES) {
+      "Invalid option value for $OPTION_GENERATED. Found $it, allowable values are ${POSSIBLE_GENERATED_NAMES.keys}."
+    }
+  }
+  private val generateProguardRules = environment.options[OPTION_GENERATE_PROGUARD_RULES]?.toBooleanStrictOrNull() ?: true
+
+  override fun process(resolver: Resolver): List<KSAnnotated> {
+    val generatedAnnotation = generatedOption?.let {
+      val annotationType = resolver.getClassDeclarationByName(resolver.getKSNameFromString(it))
+        ?: run {
+          logger.error("Generated annotation type doesn't exist: $it")
+          return emptyList()
+        }
+      AnnotationSpec.builder(annotationType.toClassName())
+        .addMember("value = [%S]", JsonClassSymbolProcessor::class.java.canonicalName)
+        .addMember("comments = %S", "https://github.com/square/moshi")
+        .build()
+    }
+
+    resolver.getSymbolsWithAnnotation(JSON_CLASS_NAME)
+      .asSequence()
+      .forEach { type ->
+        // For the smart cast
+        if (type !is KSDeclaration) {
+          logger.error("@JsonClass can't be applied to $type: must be a Kotlin class", type)
+          return@forEach
+        }
+
+        val jsonClassAnnotation = type.findAnnotationWithType<JsonClass>() ?: return@forEach
+
+        val generator = jsonClassAnnotation.generator
+
+        if (generator.isNotEmpty()) return@forEach
+
+        if (!jsonClassAnnotation.generateAdapter) return@forEach
+
+        val originatingFile = type.containingFile!!
+        val adapterGenerator = adapterGenerator(logger, resolver, type) ?: return emptyList()
+        try {
+          val preparedAdapter = adapterGenerator
+            .prepare(generateProguardRules) { spec ->
+              spec.toBuilder()
+                .apply {
+                  generatedAnnotation?.let(::addAnnotation)
+                }
+                .addOriginatingKSFile(originatingFile)
+                .build()
+            }
+          preparedAdapter.spec.writeTo(codeGenerator, aggregating = false)
+          preparedAdapter.proguardConfig?.writeTo(codeGenerator, originatingFile)
+        } catch (e: Exception) {
+          logger.error(
+            "Error preparing ${type.simpleName.asString()}: ${e.stackTrace.joinToString("\n")}"
+          )
+        }
+      }
+    return emptyList()
+  }
+
+  private fun adapterGenerator(
+    logger: KSPLogger,
+    resolver: Resolver,
+    originalType: KSDeclaration,
+  ): AdapterGenerator? {
+    val type = targetType(originalType, resolver, logger) ?: return null
+
+    val properties = mutableMapOf<String, PropertyGenerator>()
+    for (property in type.properties.values) {
+      val generator = property.generator(logger, resolver, originalType)
+      if (generator != null) {
+        properties[property.name] = generator
+      }
+    }
+
+    for ((name, parameter) in type.constructor.parameters) {
+      if (type.properties[parameter.name] == null && !parameter.hasDefault) {
+        // TODO would be nice if we could pass the parameter node directly?
+        logger.error("No property for required constructor parameter $name", originalType)
+        return null
+      }
+    }
+
+    // Sort properties so that those with constructor parameters come first.
+    val sortedProperties = properties.values.sortedBy {
+      if (it.hasConstructorParameter) {
+        it.target.parameterIndex
+      } else {
+        Integer.MAX_VALUE
+      }
+    }
+
+    return AdapterGenerator(type, sortedProperties)
+  }
+}
+
+/** Writes this config to a [codeGenerator]. */
+private fun ProguardConfig.writeTo(codeGenerator: CodeGenerator, originatingKSFile: KSFile) {
+  val file = codeGenerator.createNewFile(
+    dependencies = Dependencies(aggregating = false, originatingKSFile),
+    packageName = "",
+    fileName = outputFilePathWithoutExtension(targetClass.canonicalName),
+    extensionName = "pro"
+  )
+  // Don't use writeTo(file) because that tries to handle directories under the hood
+  OutputStreamWriter(file, StandardCharsets.UTF_8)
+    .use(::writeTo)
+}
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/KspUtil.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/KspUtil.kt
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.ksp
+
+import com.google.devtools.ksp.processing.KSPLogger
+import com.google.devtools.ksp.processing.Resolver
+import com.google.devtools.ksp.symbol.ClassKind
+import com.google.devtools.ksp.symbol.KSAnnotated
+import com.google.devtools.ksp.symbol.KSAnnotation
+import com.google.devtools.ksp.symbol.KSClassDeclaration
+import com.google.devtools.ksp.symbol.KSName
+import com.google.devtools.ksp.symbol.KSNode
+import com.google.devtools.ksp.symbol.KSType
+import com.google.devtools.ksp.symbol.KSTypeAlias
+import com.google.devtools.ksp.symbol.Origin.KOTLIN
+import com.google.devtools.ksp.symbol.Origin.KOTLIN_LIB
+import com.squareup.kotlinpoet.AnnotationSpec
+import com.squareup.kotlinpoet.ClassName
+import com.squareup.kotlinpoet.CodeBlock
+import com.squareup.kotlinpoet.ksp.toClassName
+
+internal fun KSClassDeclaration.asType() = asType(emptyList())
+
+internal fun KSClassDeclaration.isKotlinClass(): Boolean {
+  return origin == KOTLIN ||
+    origin == KOTLIN_LIB ||
+    isAnnotationPresent(Metadata::class)
+}
+
+internal inline fun <reified T : Annotation> KSAnnotated.findAnnotationWithType(): T? {
+  return getAnnotationsByType(T::class).firstOrNull()
+}
+
+internal fun KSType.unwrapTypeAlias(): KSType {
+  return if (this.declaration is KSTypeAlias) {
+    (this.declaration as KSTypeAlias).type.resolve()
+  } else {
+    this
+  }
+}
+
+internal fun KSAnnotation.toAnnotationSpec(resolver: Resolver): AnnotationSpec {
+  val element = annotationType.resolve().unwrapTypeAlias().declaration as KSClassDeclaration
+  val builder = AnnotationSpec.builder(element.toClassName())
+  for (argument in arguments) {
+    val member = CodeBlock.builder()
+    val name = argument.name!!.getShortName()
+    member.add("%L = ", name)
+    addValueToBlock(argument.value!!, resolver, member)
+    builder.addMember(member.build())
+  }
+  return builder.build()
+}
+
+private fun addValueToBlock(value: Any, resolver: Resolver, member: CodeBlock.Builder) {
+  when (value) {
+    is List<*> -> {
+      // Array type
+      member.add("[⇥⇥")
+      value.forEachIndexed { index, innerValue ->
+        if (index > 0) member.add(", ")
+        addValueToBlock(innerValue!!, resolver, member)
+      }
+      member.add("⇤⇤]")
+    }
+    is KSType -> {
+      val unwrapped = value.unwrapTypeAlias()
+      val isEnum = (unwrapped.declaration as KSClassDeclaration).classKind == ClassKind.ENUM_ENTRY
+      if (isEnum) {
+        val parent = unwrapped.declaration.parentDeclaration as KSClassDeclaration
+        val entry = unwrapped.declaration.simpleName.getShortName()
+        member.add("%T.%L", parent.toClassName(), entry)
+      } else {
+        member.add("%T::class", unwrapped.toClassName())
+      }
+    }
+    is KSName ->
+      member.add(
+        "%T.%L", ClassName.bestGuess(value.getQualifier()),
+        value.getShortName()
+      )
+    is KSAnnotation -> member.add("%L", value.toAnnotationSpec(resolver))
+    else -> member.add(memberForValue(value))
+  }
+}
+
+/**
+ * Creates a [CodeBlock] with parameter `format` depending on the given `value` object.
+ * Handles a number of special cases, such as appending "f" to `Float` values, and uses
+ * `%L` for other types.
+ */
+internal fun memberForValue(value: Any) = when (value) {
+  is Class<*> -> CodeBlock.of("%T::class", value)
+  is Enum<*> -> CodeBlock.of("%T.%L", value.javaClass, value.name)
+  is String -> CodeBlock.of("%S", value)
+  is Float -> CodeBlock.of("%Lf", value)
+  is Double -> CodeBlock.of("%L", value)
+  is Char -> CodeBlock.of("$value.toChar()")
+  is Byte -> CodeBlock.of("$value.toByte()")
+  is Short -> CodeBlock.of("$value.toShort()")
+  // Int or Boolean
+  else -> CodeBlock.of("%L", value)
+}
+
+internal inline fun KSPLogger.check(condition: Boolean, message: () -> String) {
+  check(condition, null, message)
+}
+
+internal inline fun KSPLogger.check(condition: Boolean, element: KSNode?, message: () -> String) {
+  if (!condition) {
+    error(message(), element)
+  }
+}
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/MoshiApiUtil.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/MoshiApiUtil.kt
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.ksp
+
+import com.google.devtools.ksp.processing.KSPLogger
+import com.google.devtools.ksp.processing.Resolver
+import com.google.devtools.ksp.symbol.KSClassDeclaration
+import com.google.devtools.ksp.symbol.KSDeclaration
+import com.squareup.kotlinpoet.AnnotationSpec
+import com.squareup.kotlinpoet.KModifier
+import com.squareup.kotlinpoet.asClassName
+import com.squareup.moshi.JsonQualifier
+import com.squareup.moshi.kotlin.codegen.api.DelegateKey
+import com.squareup.moshi.kotlin.codegen.api.PropertyGenerator
+import com.squareup.moshi.kotlin.codegen.api.TargetProperty
+import com.squareup.moshi.kotlin.codegen.api.rawType
+
+private val VISIBILITY_MODIFIERS = setOf(
+  KModifier.INTERNAL,
+  KModifier.PRIVATE,
+  KModifier.PROTECTED,
+  KModifier.PUBLIC
+)
+
+internal fun Collection<KModifier>.visibility(): KModifier {
+  return find { it in VISIBILITY_MODIFIERS } ?: KModifier.PUBLIC
+}
+
+private val TargetProperty.isTransient get() = propertySpec.annotations.any { it.typeName == Transient::class.asClassName() }
+private val TargetProperty.isSettable get() = propertySpec.mutable || parameter != null
+private val TargetProperty.isVisible: Boolean
+  get() {
+    return visibility == KModifier.INTERNAL ||
+      visibility == KModifier.PROTECTED ||
+      visibility == KModifier.PUBLIC
+  }
+
+/**
+ * Returns a generator for this property, or null if either there is an error and this property
+ * cannot be used with code gen, or if no codegen is necessary for this property.
+ */
+internal fun TargetProperty.generator(
+  logger: KSPLogger,
+  resolver: Resolver,
+  originalType: KSDeclaration
+): PropertyGenerator? {
+  if (isTransient) {
+    if (!hasDefault) {
+      logger.error(
+        "No default value for transient property $name",
+        originalType
+      )
+      return null
+    }
+    return PropertyGenerator(this, DelegateKey(type, emptyList()), true)
+  }
+
+  if (!isVisible) {
+    logger.error(
+      "property $name is not visible",
+      originalType
+    )
+    return null
+  }
+
+  if (!isSettable) {
+    return null // This property is not settable. Ignore it.
+  }
+
+  // Merge parameter and property annotations
+  val qualifiers = parameter?.qualifiers.orEmpty() + propertySpec.annotations
+  for (jsonQualifier in qualifiers) {
+    val qualifierRawType = jsonQualifier.typeName.rawType()
+    // Check Java types since that covers both Java and Kotlin annotations.
+    resolver.getClassDeclarationByName(qualifierRawType.canonicalName)?.let { annotationElement ->
+      annotationElement.findAnnotationWithType<Retention>()?.let {
+        if (it.value != AnnotationRetention.RUNTIME) {
+          logger.error(
+            "JsonQualifier @${qualifierRawType.simpleName} must have RUNTIME retention"
+          )
+        }
+      }
+      annotationElement.findAnnotationWithType<Target>()?.let {
+        if (AnnotationTarget.FIELD !in it.allowedTargets) {
+          logger.error(
+            "JsonQualifier @${qualifierRawType.simpleName} must support FIELD target"
+          )
+        }
+      }
+    }
+  }
+
+  val jsonQualifierSpecs = qualifiers.map {
+    it.toBuilder()
+      .useSiteTarget(AnnotationSpec.UseSiteTarget.FIELD)
+      .build()
+  }
+
+  return PropertyGenerator(
+    this,
+    DelegateKey(type, jsonQualifierSpecs)
+  )
+}
+
+internal val KSClassDeclaration.isJsonQualifier: Boolean
+  get() = isAnnotationPresent(JsonQualifier::class)
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/TargetTypes.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/TargetTypes.kt
@@ -0,0 +1,280 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.ksp
+
+import com.google.devtools.ksp.KspExperimental
+import com.google.devtools.ksp.getDeclaredProperties
+import com.google.devtools.ksp.getVisibility
+import com.google.devtools.ksp.isInternal
+import com.google.devtools.ksp.isLocal
+import com.google.devtools.ksp.isPublic
+import com.google.devtools.ksp.processing.KSPLogger
+import com.google.devtools.ksp.processing.Resolver
+import com.google.devtools.ksp.symbol.ClassKind
+import com.google.devtools.ksp.symbol.ClassKind.CLASS
+import com.google.devtools.ksp.symbol.KSAnnotated
+import com.google.devtools.ksp.symbol.KSClassDeclaration
+import com.google.devtools.ksp.symbol.KSDeclaration
+import com.google.devtools.ksp.symbol.KSPropertyDeclaration
+import com.google.devtools.ksp.symbol.KSType
+import com.google.devtools.ksp.symbol.KSTypeParameter
+import com.google.devtools.ksp.symbol.Modifier
+import com.google.devtools.ksp.symbol.Origin
+import com.squareup.kotlinpoet.AnnotationSpec
+import com.squareup.kotlinpoet.ClassName
+import com.squareup.kotlinpoet.KModifier
+import com.squareup.kotlinpoet.ParameterizedTypeName.Companion.parameterizedBy
+import com.squareup.kotlinpoet.PropertySpec
+import com.squareup.kotlinpoet.TypeName
+import com.squareup.kotlinpoet.ksp.TypeParameterResolver
+import com.squareup.kotlinpoet.ksp.toClassName
+import com.squareup.kotlinpoet.ksp.toKModifier
+import com.squareup.kotlinpoet.ksp.toTypeName
+import com.squareup.kotlinpoet.ksp.toTypeParameterResolver
+import com.squareup.kotlinpoet.ksp.toTypeVariableName
+import com.squareup.moshi.Json
+import com.squareup.moshi.JsonQualifier
+import com.squareup.moshi.kotlin.codegen.api.TargetConstructor
+import com.squareup.moshi.kotlin.codegen.api.TargetParameter
+import com.squareup.moshi.kotlin.codegen.api.TargetProperty
+import com.squareup.moshi.kotlin.codegen.api.TargetType
+import com.squareup.moshi.kotlin.codegen.api.unwrapTypeAlias
+
+/** Returns a target type for `element`, or null if it cannot be used with code gen. */
+internal fun targetType(
+  type: KSDeclaration,
+  resolver: Resolver,
+  logger: KSPLogger,
+): TargetType? {
+  if (type !is KSClassDeclaration) {
+    logger.error("@JsonClass can't be applied to ${type.qualifiedName?.asString()}: must be a Kotlin class", type)
+    return null
+  }
+  logger.check(type.classKind != ClassKind.ENUM_CLASS, type) {
+    "@JsonClass with 'generateAdapter = \"true\"' can't be applied to ${type.qualifiedName?.asString()}: code gen for enums is not supported or necessary"
+  }
+  logger.check(type.classKind == CLASS && type.origin == Origin.KOTLIN, type) {
+    "@JsonClass can't be applied to ${type.qualifiedName?.asString()}: must be a Kotlin class"
+  }
+  logger.check(Modifier.INNER !in type.modifiers, type) {
+    "@JsonClass can't be applied to ${type.qualifiedName?.asString()}: must not be an inner class"
+  }
+  logger.check(Modifier.SEALED !in type.modifiers, type) {
+    "@JsonClass can't be applied to ${type.qualifiedName?.asString()}: must not be sealed"
+  }
+  logger.check(Modifier.ABSTRACT !in type.modifiers, type) {
+    "@JsonClass can't be applied to ${type.qualifiedName?.asString()}: must not be abstract"
+  }
+  logger.check(!type.isLocal(), type) {
+    "@JsonClass can't be applied to ${type.qualifiedName?.asString()}: must not be local"
+  }
+  logger.check(type.isPublic() || type.isInternal(), type) {
+    "@JsonClass can't be applied to ${type.qualifiedName?.asString()}: must be internal or public"
+  }
+
+  val classTypeParamsResolver = type.typeParameters.toTypeParameterResolver(
+    sourceTypeHint = type.qualifiedName!!.asString()
+  )
+  val typeVariables = type.typeParameters.map { it.toTypeVariableName(classTypeParamsResolver) }
+  val appliedType = AppliedType.get(type)
+
+  val constructor = primaryConstructor(resolver, type, classTypeParamsResolver, logger)
+    ?: run {
+      logger.error("No primary constructor found on $type", type)
+      return null
+    }
+  if (constructor.visibility != KModifier.INTERNAL && constructor.visibility != KModifier.PUBLIC) {
+    logger.error(
+      "@JsonClass can't be applied to $type: " +
+        "primary constructor is not internal or public",
+      type
+    )
+    return null
+  }
+
+  val properties = mutableMapOf<String, TargetProperty>()
+
+  val originalType = appliedType.type
+  for (supertype in appliedType.supertypes(resolver)) {
+    val classDecl = supertype.type
+    if (!classDecl.isKotlinClass()) {
+      logger.error(
+        """
+        @JsonClass can't be applied to $type: supertype $supertype is not a Kotlin type.
+        Origin=${classDecl.origin}
+        Annotations=${classDecl.annotations.joinToString(prefix = "[", postfix = "]") { it.shortName.getShortName() }}
+        """.trimIndent(),
+        type
+      )
+      return null
+    }
+    val supertypeProperties = declaredProperties(
+      constructor = constructor,
+      originalType = originalType,
+      classDecl = classDecl,
+      resolver = resolver,
+      typeParameterResolver = classDecl.typeParameters
+        .toTypeParameterResolver(classTypeParamsResolver)
+    )
+    for ((name, property) in supertypeProperties) {
+      properties.putIfAbsent(name, property)
+    }
+  }
+  val visibility = type.getVisibility().toKModifier() ?: KModifier.PUBLIC
+  // If any class in the enclosing class hierarchy is internal, they must all have internal
+  // generated adapters.
+  val resolvedVisibility = if (visibility == KModifier.INTERNAL) {
+    // Our nested type is already internal, no need to search
+    visibility
+  } else {
+    // Implicitly public, so now look up the hierarchy
+    val forceInternal = generateSequence<KSDeclaration>(type) { it.parentDeclaration }
+      .filterIsInstance<KSClassDeclaration>()
+      .any { it.isInternal() }
+    if (forceInternal) KModifier.INTERNAL else visibility
+  }
+  return TargetType(
+    typeName = type.toClassName().withTypeArguments(typeVariables),
+    constructor = constructor,
+    properties = properties,
+    typeVariables = typeVariables,
+    isDataClass = Modifier.DATA in type.modifiers,
+    visibility = resolvedVisibility
+  )
+}
+
+private fun ClassName.withTypeArguments(arguments: List<TypeName>): TypeName {
+  return if (arguments.isEmpty()) {
+    this
+  } else {
+    this.parameterizedBy(arguments)
+  }
+}
+
+@OptIn(KspExperimental::class)
+internal fun primaryConstructor(
+  resolver: Resolver,
+  targetType: KSClassDeclaration,
+  typeParameterResolver: TypeParameterResolver,
+  logger: KSPLogger
+): TargetConstructor? {
+  val primaryConstructor = targetType.primaryConstructor ?: return null
+
+  val parameters = LinkedHashMap<String, TargetParameter>()
+  for ((index, parameter) in primaryConstructor.parameters.withIndex()) {
+    val name = parameter.name!!.getShortName()
+    parameters[name] = TargetParameter(
+      name = name,
+      index = index,
+      type = parameter.type.toTypeName(typeParameterResolver),
+      hasDefault = parameter.hasDefault,
+      qualifiers = parameter.qualifiers(resolver),
+      jsonName = parameter.jsonName()
+    )
+  }
+
+  val kmConstructorSignature: String = resolver.mapToJvmSignature(primaryConstructor)
+    ?: run {
+      logger.error("No primary constructor found.", primaryConstructor)
+      return null
+    }
+  return TargetConstructor(
+    parameters,
+    primaryConstructor.getVisibility().toKModifier() ?: KModifier.PUBLIC,
+    kmConstructorSignature
+  )
+}
+
+private fun KSAnnotated?.qualifiers(resolver: Resolver): Set<AnnotationSpec> {
+  if (this == null) return setOf()
+  return annotations
+    .filter {
+      it.annotationType.resolve().declaration.isAnnotationPresent(JsonQualifier::class)
+    }
+    .mapTo(mutableSetOf()) {
+      it.toAnnotationSpec(resolver)
+    }
+}
+
+private fun KSAnnotated?.jsonName(): String? {
+  return this?.findAnnotationWithType<Json>()?.name
+}
+
+private fun declaredProperties(
+  constructor: TargetConstructor,
+  originalType: KSClassDeclaration,
+  classDecl: KSClassDeclaration,
+  resolver: Resolver,
+  typeParameterResolver: TypeParameterResolver,
+): Map<String, TargetProperty> {
+
+  val result = mutableMapOf<String, TargetProperty>()
+  for (property in classDecl.getDeclaredProperties()) {
+    val initialType = property.type.resolve()
+    val resolvedType = if (initialType.declaration is KSTypeParameter) {
+      property.asMemberOf(originalType.asType())
+    } else {
+      initialType
+    }
+    val propertySpec = property.toPropertySpec(resolver, resolvedType, typeParameterResolver)
+    val name = propertySpec.name
+    val parameter = constructor.parameters[name]
+    result[name] = TargetProperty(
+      propertySpec = propertySpec,
+      parameter = parameter,
+      visibility = property.getVisibility().toKModifier() ?: KModifier.PUBLIC,
+      jsonName = parameter?.jsonName ?: property.jsonName()
+        ?: name.escapeDollarSigns()
+    )
+  }
+
+  return result
+}
+
+private fun KSPropertyDeclaration.toPropertySpec(
+  resolver: Resolver,
+  resolvedType: KSType,
+  typeParameterResolver: TypeParameterResolver,
+): PropertySpec {
+  return PropertySpec.builder(
+    name = simpleName.getShortName(),
+    type = resolvedType.toTypeName(typeParameterResolver).unwrapTypeAlias()
+  )
+    .mutable(isMutable)
+    .addModifiers(modifiers.map { KModifier.valueOf(it.name) })
+    .apply {
+      if (isAnnotationPresent(Transient::class)) {
+        addAnnotation(Transient::class)
+      }
+      addAnnotations(
+        this@toPropertySpec.annotations
+          .mapNotNull {
+            if ((it.annotationType.resolve().unwrapTypeAlias().declaration as KSClassDeclaration).isJsonQualifier
+            ) {
+              it.toAnnotationSpec(resolver)
+            } else {
+              null
+            }
+          }
+          .asIterable()
+      )
+    }
+    .build()
+}
+
+private fun String.escapeDollarSigns(): String {
+  return replace("\$", "\${\'\$\'}")
+}
--- a/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/shadedUtil.kt
+++ b/kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/ksp/shadedUtil.kt
@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) 2020 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.ksp
+
+import com.google.devtools.ksp.processing.Resolver
+import com.google.devtools.ksp.symbol.KSAnnotated
+import com.google.devtools.ksp.symbol.KSAnnotation
+import com.google.devtools.ksp.symbol.KSClassDeclaration
+import com.google.devtools.ksp.symbol.KSType
+import com.google.devtools.ksp.symbol.KSValueArgument
+import java.lang.reflect.InvocationHandler
+import java.lang.reflect.Method
+import java.lang.reflect.Proxy
+import java.util.concurrent.ConcurrentHashMap
+import kotlin.reflect.KClass
+
+/*
+ * Copied experimental utilities from KSP.
+ */
+
+/**
+ * Find a class in the compilation classpath for the given name.
+ *
+ * @param name fully qualified name of the class to be loaded; using '.' as separator.
+ * @return a KSClassDeclaration, or null if not found.
+ */
+internal fun Resolver.getClassDeclarationByName(name: String): KSClassDeclaration? =
+  getClassDeclarationByName(getKSNameFromString(name))
+
+internal fun <T : Annotation> KSAnnotated.getAnnotationsByType(annotationKClass: KClass<T>): Sequence<T> {
+  return this.annotations.filter {
+    it.shortName.getShortName() == annotationKClass.simpleName && it.annotationType.resolve().declaration
+      .qualifiedName?.asString() == annotationKClass.qualifiedName
+  }.map { it.toAnnotation(annotationKClass.java) }
+}
+
+internal fun <T : Annotation> KSAnnotated.isAnnotationPresent(annotationKClass: KClass<T>): Boolean =
+  getAnnotationsByType(annotationKClass).firstOrNull() != null
+
+@Suppress("UNCHECKED_CAST")
+private fun <T : Annotation> KSAnnotation.toAnnotation(annotationClass: Class<T>): T {
+  return Proxy.newProxyInstance(
+    annotationClass.classLoader,
+    arrayOf(annotationClass),
+    createInvocationHandler(annotationClass)
+  ) as T
+}
+
+@Suppress("TooGenericExceptionCaught")
+private fun KSAnnotation.createInvocationHandler(clazz: Class<*>): InvocationHandler {
+  val cache = ConcurrentHashMap<Pair<Class<*>, Any>, Any>(arguments.size)
+  return InvocationHandler { proxy, method, _ ->
+    if (method.name == "toString" && arguments.none { it.name?.asString() == "toString" }) {
+      clazz.canonicalName +
+        arguments.map { argument: KSValueArgument ->
+          // handles default values for enums otherwise returns null
+          val methodName = argument.name?.asString()
+          val value = proxy.javaClass.methods.find { m -> m.name == methodName }?.invoke(proxy)
+          "$methodName=$value"
+        }.toList()
+    } else {
+      val argument = try {
+        arguments.first { it.name?.asString() == method.name }
+      } catch (e: NullPointerException) {
+        throw IllegalArgumentException("This is a bug using the default KClass for an annotation", e)
+      }
+      when (val result = argument.value ?: method.defaultValue) {
+        is Proxy -> result
+        is List<*> -> {
+          val value = { result.asArray(method) }
+          cache.getOrPut(Pair(method.returnType, result), value)
+        }
+        else -> {
+          when {
+            method.returnType.isEnum -> {
+              val value = { result.asEnum(method.returnType) }
+              cache.getOrPut(Pair(method.returnType, result), value)
+            }
+            method.returnType.isAnnotation -> {
+              val value = { (result as KSAnnotation).asAnnotation(method.returnType) }
+              cache.getOrPut(Pair(method.returnType, result), value)
+            }
+            method.returnType.name == "java.lang.Class" -> {
+              val value = { (result as KSType).asClass() }
+              cache.getOrPut(Pair(method.returnType, result), value)
+            }
+            method.returnType.name == "byte" -> {
+              val value = { result.asByte() }
+              cache.getOrPut(Pair(method.returnType, result), value)
+            }
+            method.returnType.name == "short" -> {
+              val value = { result.asShort() }
+              cache.getOrPut(Pair(method.returnType, result), value)
+            }
+            else -> result // original value
+          }
+        }
+      }
+    }
+  }
+}
+
+@Suppress("UNCHECKED_CAST")
+private fun KSAnnotation.asAnnotation(
+  annotationInterface: Class<*>,
+): Any {
+  return Proxy.newProxyInstance(
+    this.javaClass.classLoader, arrayOf(annotationInterface),
+    this.createInvocationHandler(annotationInterface)
+  ) as Proxy
+}
+
+@Suppress("UNCHECKED_CAST")
+private fun List<*>.asArray(method: Method) =
+  when (method.returnType.componentType.name) {
+    "boolean" -> (this as List<Boolean>).toBooleanArray()
+    "byte" -> (this as List<Byte>).toByteArray()
+    "short" -> (this as List<Short>).toShortArray()
+    "char" -> (this as List<Char>).toCharArray()
+    "double" -> (this as List<Double>).toDoubleArray()
+    "float" -> (this as List<Float>).toFloatArray()
+    "int" -> (this as List<Int>).toIntArray()
+    "long" -> (this as List<Long>).toLongArray()
+    "java.lang.Class" -> (this as List<KSType>).map {
+      Class.forName(it.declaration.qualifiedName!!.asString())
+    }.toTypedArray()
+    "java.lang.String" -> (this as List<String>).toTypedArray()
+    else -> { // arrays of enums or annotations
+      when {
+        method.returnType.componentType.isEnum -> {
+          this.toArray(method) { result -> result.asEnum(method.returnType.componentType) }
+        }
+        method.returnType.componentType.isAnnotation -> {
+          this.toArray(method) { result ->
+            (result as KSAnnotation).asAnnotation(method.returnType.componentType)
+          }
+        }
+        else -> throw IllegalStateException("Unable to process type ${method.returnType.componentType.name}")
+      }
+    }
+  }
+
+@Suppress("UNCHECKED_CAST")
+private fun List<*>.toArray(method: Method, valueProvider: (Any) -> Any): Array<Any?> {
+  val array: Array<Any?> = java.lang.reflect.Array.newInstance(
+    method.returnType.componentType,
+    this.size
+  ) as Array<Any?>
+  for (r in 0 until this.size) {
+    array[r] = this[r]?.let { valueProvider.invoke(it) }
+  }
+  return array
+}
+
+@Suppress("UNCHECKED_CAST")
+private fun <T> Any.asEnum(returnType: Class<T>): T =
+  returnType.getDeclaredMethod("valueOf", String::class.java)
+    .invoke(
+      null,
+      // Change from upstream KSP - https://github.com/google/ksp/pull/685
+      if (this is KSType) {
+        this.declaration.simpleName.getShortName()
+      } else {
+        this.toString()
+      }
+    ) as T
+
+private fun Any.asByte(): Byte = if (this is Int) this.toByte() else this as Byte
+
+private fun Any.asShort(): Short = if (this is Int) this.toShort() else this as Short
+
+private fun KSType.asClass() = Class.forName(this.declaration.qualifiedName!!.asString())
--- a/kotlin/codegen/src/main/resources/META-INF/gradle/incremental.annotation.processors
+++ b/kotlin/codegen/src/main/resources/META-INF/gradle/incremental.annotation.processors
@@ -0,0 +1 @@
+com.squareup.moshi.kotlin.codegen.apt.JsonClassCodegenProcessor,ISOLATING
--- a/kotlin/codegen/src/test/java/com/squareup/moshi/kotlin/codegen/apt/JsonClassCodegenProcessorTest.kt
+++ b/kotlin/codegen/src/test/java/com/squareup/moshi/kotlin/codegen/apt/JsonClassCodegenProcessorTest.kt
@@ -18,6 +18,9 @@ package com.squareup.moshi.kotlin.codegen.apt
 import com.google.common.truth.Truth.assertThat
 import com.squareup.moshi.JsonAdapter
 import com.squareup.moshi.JsonReader
+import com.squareup.moshi.kotlin.codegen.api.Options
+import com.squareup.moshi.kotlin.codegen.api.Options.OPTION_GENERATED
+import com.squareup.moshi.kotlin.codegen.api.Options.OPTION_GENERATE_PROGUARD_RULES
 import com.tschuchort.compiletesting.KotlinCompilation
 import com.tschuchort.compiletesting.SourceFile
 import com.tschuchort.compiletesting.SourceFile.Companion.kotlin
@@ -324,7 +327,6 @@ class JsonClassCodegenProcessorTest {
        """
          import com.squareup.moshi.JsonClass

-          import com.squareup.moshi.JsonClass
          @JsonClass(generateAdapter = true)
          class NonPropertyConstructorParameter(a: Int, val b: Int)
          """
@@ -349,10 +351,10 @@ class JsonClassCodegenProcessorTest {
          """
      )
    ).apply {
-      kaptArgs[JsonClassCodegenProcessor.OPTION_GENERATED] = "javax.annotation.GeneratedBlerg"
+      kaptArgs[OPTION_GENERATED] = "javax.annotation.GeneratedBlerg"
    }.compile()
    assertThat(result.messages).contains(
-      "Invalid option value for ${JsonClassCodegenProcessor.OPTION_GENERATED}"
+      "Invalid option value for $OPTION_GENERATED"
    )
  }
  @Test
@@ -368,7 +370,7 @@ class JsonClassCodegenProcessorTest {
          """
      )
    ).apply {
-      kaptArgs[JsonClassCodegenProcessor.OPTION_GENERATE_PROGUARD_RULES] = "false"
+      kaptArgs[OPTION_GENERATE_PROGUARD_RULES] = "false"
    }.compile()
    assertThat(result.generatedFiles.filter { it.endsWith(".pro") }).isEmpty()
  }
--- a/kotlin/codegen/src/test/java/com/squareup/moshi/kotlin/codegen/ksp/JsonClassSymbolProcessorTest.kt
+++ b/kotlin/codegen/src/test/java/com/squareup/moshi/kotlin/codegen/ksp/JsonClassSymbolProcessorTest.kt
@@ -0,0 +1,824 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.ksp
+
+import com.google.common.truth.Truth.assertThat
+import com.squareup.moshi.kotlin.codegen.api.Options.OPTION_GENERATED
+import com.squareup.moshi.kotlin.codegen.api.Options.OPTION_GENERATE_PROGUARD_RULES
+import com.tschuchort.compiletesting.KotlinCompilation
+import com.tschuchort.compiletesting.SourceFile
+import com.tschuchort.compiletesting.SourceFile.Companion.java
+import com.tschuchort.compiletesting.SourceFile.Companion.kotlin
+import com.tschuchort.compiletesting.kspArgs
+import com.tschuchort.compiletesting.kspIncremental
+import com.tschuchort.compiletesting.kspSourcesDir
+import com.tschuchort.compiletesting.symbolProcessorProviders
+import org.junit.Ignore
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.TemporaryFolder
+import kotlin.reflect.KClassifier
+import kotlin.reflect.KType
+import kotlin.reflect.KTypeProjection
+import kotlin.reflect.KVariance
+import kotlin.reflect.KVariance.INVARIANT
+import kotlin.reflect.full.createType
+
+/** Execute kotlinc to confirm that either files are generated or errors are printed. */
+class JsonClassSymbolProcessorTest {
+
+  @Rule @JvmField var temporaryFolder: TemporaryFolder = TemporaryFolder()
+
+  @Test
+  fun privateConstructor() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          class PrivateConstructor private constructor(var a: Int, var b: Int) {
+            fun a() = a
+            fun b() = b
+            companion object {
+              fun newInstance(a: Int, b: Int) = PrivateConstructor(a, b)
+            }
+          }
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains("constructor is not internal or public")
+  }
+
+  @Test
+  fun privateConstructorParameter() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          class PrivateConstructorParameter(private var a: Int)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains("property a is not visible")
+  }
+
+  @Test
+  fun privateProperties() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          class PrivateProperties {
+            private var a: Int = -1
+            private var b: Int = -1
+          }
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains("property a is not visible")
+  }
+
+  @Test
+  fun interfacesNotSupported() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          interface Interface
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "@JsonClass can't be applied to test.Interface: must be a Kotlin class"
+    )
+  }
+
+  @Test
+  fun interfacesDoNotErrorWhenGeneratorNotSet() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true, generator="customGenerator")
+          interface Interface
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.OK)
+  }
+
+  @Test
+  fun abstractClassesNotSupported() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          abstract class AbstractClass(val a: Int)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "@JsonClass can't be applied to test.AbstractClass: must not be abstract"
+    )
+  }
+
+  @Test
+  fun sealedClassesNotSupported() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          sealed class SealedClass(val a: Int)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "@JsonClass can't be applied to test.SealedClass: must not be sealed"
+    )
+  }
+
+  @Test
+  fun innerClassesNotSupported() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          class Outer {
+            @JsonClass(generateAdapter = true)
+            inner class InnerClass(val a: Int)
+          }
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "@JsonClass can't be applied to test.Outer.InnerClass: must not be an inner class"
+    )
+  }
+
+  @Test
+  fun enumClassesNotSupported() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          enum class KotlinEnum {
+            A, B
+          }
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "@JsonClass with 'generateAdapter = \"true\"' can't be applied to test.KotlinEnum: code gen for enums is not supported or necessary"
+    )
+  }
+
+  // Annotation processors don't get called for local classes, so we don't have the opportunity to
+  @Ignore
+  @Test
+  fun localClassesNotSupported() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          fun outer() {
+            @JsonClass(generateAdapter = true)
+            class LocalClass(val a: Int)
+          }
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "@JsonClass can't be applied to LocalClass: must not be local"
+    )
+  }
+
+  @Test
+  fun privateClassesNotSupported() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          private class PrivateClass(val a: Int)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "@JsonClass can't be applied to test.PrivateClass: must be internal or public"
+    )
+  }
+
+  @Test
+  fun objectDeclarationsNotSupported() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          object ObjectDeclaration {
+            var a = 5
+          }
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "@JsonClass can't be applied to test.ObjectDeclaration: must be a Kotlin class"
+    )
+  }
+
+  @Test
+  fun objectExpressionsNotSupported() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          val expression = object : Any() {
+            var a = 5
+          }
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "@JsonClass can't be applied to test.expression: must be a Kotlin class"
+    )
+  }
+
+  @Test
+  fun requiredTransientConstructorParameterFails() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          class RequiredTransientConstructorParameter(@Transient var a: Int)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "No default value for transient property a"
+    )
+  }
+
+  @Test
+  fun nonPropertyConstructorParameter() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          class NonPropertyConstructorParameter(a: Int, val b: Int)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains(
+      "No property for required constructor parameter a"
+    )
+  }
+
+  @Test
+  fun badGeneratedAnnotation() {
+    val result = prepareCompilation(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          data class Foo(val a: Int)
+          """
+      )
+    ).apply {
+      kspArgs[OPTION_GENERATED] = "javax.annotation.GeneratedBlerg"
+    }.compile()
+    assertThat(result.messages).contains(
+      "Invalid option value for $OPTION_GENERATED"
+    )
+  }
+
+  @Test
+  fun disableProguardGeneration() {
+    val compilation = prepareCompilation(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          data class Foo(val a: Int)
+          """
+      )
+    ).apply {
+      kspArgs[OPTION_GENERATE_PROGUARD_RULES] = "false"
+    }
+    val result = compilation.compile()
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.OK)
+    assertThat(compilation.kspSourcesDir.walkTopDown().filter { it.extension == "pro" }.toList()).isEmpty()
+  }
+
+  @Test
+  fun multipleErrors() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          @JsonClass(generateAdapter = true)
+          class Class1(private var a: Int, private var b: Int)
+
+          @JsonClass(generateAdapter = true)
+          class Class2(private var c: Int)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains("property a is not visible")
+    // TODO we throw eagerly currently and don't collect
+//    assertThat(result.messages).contains("property c is not visible")
+  }
+
+  @Test
+  fun extendPlatformType() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+          import java.util.Date
+
+          @JsonClass(generateAdapter = true)
+          class ExtendsPlatformClass(var a: Int) : Date()
+          """
+      )
+    )
+    assertThat(result.messages).contains("supertype java.util.Date is not a Kotlin type")
+  }
+
+  @Test
+  fun extendJavaType() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+          import com.squareup.moshi.kotlin.codegen.JavaSuperclass
+
+          @JsonClass(generateAdapter = true)
+          class ExtendsJavaType(var b: Int) : JavaSuperclass()
+          """
+      ),
+      java(
+        "JavaSuperclass.java",
+        """
+        package com.squareup.moshi.kotlin.codegen;
+        public class JavaSuperclass {
+          public int a = 1;
+        }
+        """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages)
+      .contains("supertype com.squareup.moshi.kotlin.codegen.JavaSuperclass is not a Kotlin type")
+  }
+
+  @Test
+  fun nonFieldApplicableQualifier() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+          import com.squareup.moshi.JsonQualifier
+          import kotlin.annotation.AnnotationRetention.RUNTIME
+          import kotlin.annotation.AnnotationTarget.PROPERTY
+          import kotlin.annotation.Retention
+          import kotlin.annotation.Target
+
+          @Retention(RUNTIME)
+          @Target(PROPERTY)
+          @JsonQualifier
+          annotation class UpperCase
+
+          @JsonClass(generateAdapter = true)
+          class ClassWithQualifier(@UpperCase val a: Int)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains("JsonQualifier @UpperCase must support FIELD target")
+  }
+
+  @Test
+  fun nonRuntimeQualifier() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+          import com.squareup.moshi.JsonQualifier
+          import kotlin.annotation.AnnotationRetention.BINARY
+          import kotlin.annotation.AnnotationTarget.FIELD
+          import kotlin.annotation.AnnotationTarget.PROPERTY
+          import kotlin.annotation.Retention
+          import kotlin.annotation.Target
+
+          @Retention(BINARY)
+          @Target(PROPERTY, FIELD)
+          @JsonQualifier
+          annotation class UpperCase
+
+          @JsonClass(generateAdapter = true)
+          class ClassWithQualifier(@UpperCase val a: Int)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.COMPILATION_ERROR)
+    assertThat(result.messages).contains("JsonQualifier @UpperCase must have RUNTIME retention")
+  }
+
+  @Test
+  fun `TypeAliases with the same backing type should share the same adapter`() {
+    val result = compile(
+      kotlin(
+        "source.kt",
+        """
+          package test
+          import com.squareup.moshi.JsonClass
+
+          typealias FirstName = String
+          typealias LastName = String
+
+          @JsonClass(generateAdapter = true)
+          data class Person(val firstName: FirstName, val lastName: LastName, val hairColor: String)
+          """
+      )
+    )
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.OK)
+
+    // We're checking here that we only generate one `stringAdapter` that's used for both the
+    // regular string properties as well as the the aliased ones.
+    // TODO loading compiled classes from results not supported in KSP yet
+//    val adapterClass = result.classLoader.loadClass("PersonJsonAdapter").kotlin
+//    assertThat(adapterClass.declaredMemberProperties.map { it.returnType }).containsExactly(
+//      JsonReader.Options::class.createType(),
+//      JsonAdapter::class.parameterizedBy(String::class)
+//    )
+  }
+
+  @Test
+  fun `Processor should generate comprehensive proguard rules`() {
+    val compilation = prepareCompilation(
+      kotlin(
+        "source.kt",
+        """
+          package testPackage
+          import com.squareup.moshi.JsonClass
+          import com.squareup.moshi.JsonQualifier
+
+          typealias FirstName = String
+          typealias LastName = String
+
+          @JsonClass(generateAdapter = true)
+          data class Aliases(val firstName: FirstName, val lastName: LastName, val hairColor: String)
+
+          @JsonClass(generateAdapter = true)
+          data class Simple(val firstName: String)
+
+          @JsonClass(generateAdapter = true)
+          data class Generic<T>(val firstName: T, val lastName: String)
+
+          @JsonQualifier
+          annotation class MyQualifier
+
+          @JsonClass(generateAdapter = true)
+          data class UsingQualifiers(val firstName: String, @MyQualifier val lastName: String)
+
+          @JsonClass(generateAdapter = true)
+          data class MixedTypes(val firstName: String, val otherNames: MutableList<String>)
+
+          @JsonClass(generateAdapter = true)
+          data class DefaultParams(val firstName: String = "")
+
+          @JsonClass(generateAdapter = true)
+          data class Complex<T>(val firstName: FirstName = "", @MyQualifier val names: MutableList<String>, val genericProp: T)
+
+          object NestedType {
+            @JsonQualifier
+            annotation class NestedQualifier
+
+            @JsonClass(generateAdapter = true)
+            data class NestedSimple(@NestedQualifier val firstName: String)
+          }
+
+          @JsonClass(generateAdapter = true)
+          class MultipleMasks(
+              val arg0: Long = 0,
+              val arg1: Long = 1,
+              val arg2: Long = 2,
+              val arg3: Long = 3,
+              val arg4: Long = 4,
+              val arg5: Long = 5,
+              val arg6: Long = 6,
+              val arg7: Long = 7,
+              val arg8: Long = 8,
+              val arg9: Long = 9,
+              val arg10: Long = 10,
+              val arg11: Long,
+              val arg12: Long = 12,
+              val arg13: Long = 13,
+              val arg14: Long = 14,
+              val arg15: Long = 15,
+              val arg16: Long = 16,
+              val arg17: Long = 17,
+              val arg18: Long = 18,
+              val arg19: Long = 19,
+              @Suppress("UNUSED_PARAMETER") arg20: Long = 20,
+              val arg21: Long = 21,
+              val arg22: Long = 22,
+              val arg23: Long = 23,
+              val arg24: Long = 24,
+              val arg25: Long = 25,
+              val arg26: Long = 26,
+              val arg27: Long = 27,
+              val arg28: Long = 28,
+              val arg29: Long = 29,
+              val arg30: Long = 30,
+              val arg31: Long = 31,
+              val arg32: Long = 32,
+              val arg33: Long = 33,
+              val arg34: Long = 34,
+              val arg35: Long = 35,
+              val arg36: Long = 36,
+              val arg37: Long = 37,
+              val arg38: Long = 38,
+              @Transient val arg39: Long = 39,
+              val arg40: Long = 40,
+              val arg41: Long = 41,
+              val arg42: Long = 42,
+              val arg43: Long = 43,
+              val arg44: Long = 44,
+              val arg45: Long = 45,
+              val arg46: Long = 46,
+              val arg47: Long = 47,
+              val arg48: Long = 48,
+              val arg49: Long = 49,
+              val arg50: Long = 50,
+              val arg51: Long = 51,
+              val arg52: Long = 52,
+              @Transient val arg53: Long = 53,
+              val arg54: Long = 54,
+              val arg55: Long = 55,
+              val arg56: Long = 56,
+              val arg57: Long = 57,
+              val arg58: Long = 58,
+              val arg59: Long = 59,
+              val arg60: Long = 60,
+              val arg61: Long = 61,
+              val arg62: Long = 62,
+              val arg63: Long = 63,
+              val arg64: Long = 64,
+              val arg65: Long = 65
+          )
+          """
+      )
+    )
+    val result = compilation.compile()
+    assertThat(result.exitCode).isEqualTo(KotlinCompilation.ExitCode.OK)
+
+    compilation.kspSourcesDir.walkTopDown().filter { it.extension == "pro" }.forEach { generatedFile ->
+      when (generatedFile.nameWithoutExtension) {
+        "moshi-testPackage.Aliases" -> assertThat(generatedFile.readText()).contains(
+          """
+          -if class testPackage.Aliases
+          -keepnames class testPackage.Aliases
+          -if class testPackage.Aliases
+          -keep class testPackage.AliasesJsonAdapter {
+              public <init>(com.squareup.moshi.Moshi);
+          }
+          """.trimIndent()
+        )
+        "moshi-testPackage.Simple" -> assertThat(generatedFile.readText()).contains(
+          """
+          -if class testPackage.Simple
+          -keepnames class testPackage.Simple
+          -if class testPackage.Simple
+          -keep class testPackage.SimpleJsonAdapter {
+              public <init>(com.squareup.moshi.Moshi);
+          }
+          """.trimIndent()
+        )
+        "moshi-testPackage.Generic" -> assertThat(generatedFile.readText()).contains(
+          """
+          -if class testPackage.Generic
+          -keepnames class testPackage.Generic
+          -if class testPackage.Generic
+          -keep class testPackage.GenericJsonAdapter {
+              public <init>(com.squareup.moshi.Moshi,java.lang.reflect.Type[]);
+          }
+          """.trimIndent()
+        )
+        "moshi-testPackage.UsingQualifiers" -> assertThat(generatedFile.readText()).contains(
+          """
+          -if class testPackage.UsingQualifiers
+          -keepnames class testPackage.UsingQualifiers
+          -if class testPackage.UsingQualifiers
+          -keep class testPackage.UsingQualifiersJsonAdapter {
+              public <init>(com.squareup.moshi.Moshi);
+              private com.squareup.moshi.JsonAdapter stringAtMyQualifierAdapter;
+          }
+          -if class testPackage.UsingQualifiers
+          -keep @interface testPackage.MyQualifier
+          """.trimIndent()
+        )
+        "moshi-testPackage.MixedTypes" -> assertThat(generatedFile.readText()).contains(
+          """
+          -if class testPackage.MixedTypes
+          -keepnames class testPackage.MixedTypes
+          -if class testPackage.MixedTypes
+          -keep class testPackage.MixedTypesJsonAdapter {
+              public <init>(com.squareup.moshi.Moshi);
+          }
+          """.trimIndent()
+        )
+        "moshi-testPackage.DefaultParams" -> assertThat(generatedFile.readText()).contains(
+          """
+          -if class testPackage.DefaultParams
+          -keepnames class testPackage.DefaultParams
+          -if class testPackage.DefaultParams
+          -keep class testPackage.DefaultParamsJsonAdapter {
+              public <init>(com.squareup.moshi.Moshi);
+          }
+          -if class testPackage.DefaultParams
+          -keepnames class kotlin.jvm.internal.DefaultConstructorMarker
+          -if class testPackage.DefaultParams
+          -keepclassmembers class testPackage.DefaultParams {
+              public synthetic <init>(java.lang.String,int,kotlin.jvm.internal.DefaultConstructorMarker);
+          }
+          """.trimIndent()
+        )
+        "moshi-testPackage.Complex" -> assertThat(generatedFile.readText()).contains(
+          """
+          -if class testPackage.Complex
+          -keepnames class testPackage.Complex
+          -if class testPackage.Complex
+          -keep class testPackage.ComplexJsonAdapter {
+              public <init>(com.squareup.moshi.Moshi,java.lang.reflect.Type[]);
+              private com.squareup.moshi.JsonAdapter mutableListOfStringAtMyQualifierAdapter;
+          }
+          -if class testPackage.Complex
+          -keep @interface testPackage.MyQualifier
+          -if class testPackage.Complex
+          -keepnames class kotlin.jvm.internal.DefaultConstructorMarker
+          -if class testPackage.Complex
+          -keepclassmembers class testPackage.Complex {
+              public synthetic <init>(java.lang.String,java.util.List,java.lang.Object,int,kotlin.jvm.internal.DefaultConstructorMarker);
+          }
+          """.trimIndent()
+        )
+        "moshi-testPackage.MultipleMasks" -> assertThat(generatedFile.readText()).contains(
+          """
+          -if class testPackage.MultipleMasks
+          -keepnames class testPackage.MultipleMasks
+          -if class testPackage.MultipleMasks
+          -keep class testPackage.MultipleMasksJsonAdapter {
+              public <init>(com.squareup.moshi.Moshi);
+          }
+          -if class testPackage.MultipleMasks
+          -keepnames class kotlin.jvm.internal.DefaultConstructorMarker
+          -if class testPackage.MultipleMasks
+          -keepclassmembers class testPackage.MultipleMasks {
+              public synthetic <init>(long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,long,int,int,int,kotlin.jvm.internal.DefaultConstructorMarker);
+          }
+          """.trimIndent()
+        )
+        "moshi-testPackage.NestedType.NestedSimple" -> assertThat(generatedFile.readText()).contains(
+          """
+          -if class testPackage.NestedType${'$'}NestedSimple
+          -keepnames class testPackage.NestedType${'$'}NestedSimple
+          -if class testPackage.NestedType${'$'}NestedSimple
+          -keep class testPackage.NestedType_NestedSimpleJsonAdapter {
+              public <init>(com.squareup.moshi.Moshi);
+              private com.squareup.moshi.JsonAdapter stringAtNestedQualifierAdapter;
+          }
+          -if class testPackage.NestedType${'$'}NestedSimple
+          -keep @interface testPackage.NestedType${'$'}NestedQualifier
+          """.trimIndent()
+        )
+        else -> error("Unexpected proguard file! ${generatedFile.name}")
+      }
+    }
+  }
+
+  private fun prepareCompilation(vararg sourceFiles: SourceFile): KotlinCompilation {
+    return KotlinCompilation()
+      .apply {
+        workingDir = temporaryFolder.root
+        inheritClassPath = true
+        symbolProcessorProviders = listOf(JsonClassSymbolProcessorProvider())
+        sources = sourceFiles.asList()
+        verbose = false
+        kspIncremental = true // The default now
+      }
+  }
+
+  private fun compile(vararg sourceFiles: SourceFile): KotlinCompilation.Result {
+    return prepareCompilation(*sourceFiles).compile()
+  }
+
+  private fun KClassifier.parameterizedBy(vararg types: KType): KType {
+    return createType(
+      types.map { it.asProjection() }
+    )
+  }
+
+  private fun KType.asProjection(variance: KVariance? = INVARIANT): KTypeProjection {
+    return KTypeProjection(variance, this)
+  }
+}
--- a/kotlin/tests/build.gradle.kts
+++ b/kotlin/tests/build.gradle.kts
@@ -18,7 +18,15 @@ import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

 plugins {
  kotlin("jvm")
-  kotlin("kapt")
+  kotlin("kapt") apply false
+  alias(libs.plugins.ksp) apply false
+}
+
+val useKsp = hasProperty("useKsp")
+if (useKsp) {
+  apply(plugin = "com.google.devtools.ksp")
+} else {
+  apply(plugin = "org.jetbrains.kotlin.kapt")
 }

 tasks.withType<Test>().configureEach {
@@ -37,9 +45,14 @@ tasks.withType<KotlinCompile>().configureEach {
 }

 dependencies {
-  kaptTest(project(":kotlin:codegen"))
+  if (useKsp) {
+    "kspTest"(project(":kotlin:codegen"))
+  } else {
+    "kaptTest"(project(":kotlin:codegen"))
+  }
  testImplementation(project(":moshi"))
  testImplementation(project(":kotlin:reflect"))
+  testImplementation(project(":kotlin:tests:extra-moshi-test-module"))
  testImplementation(kotlin("reflect"))
  testImplementation(libs.junit)
  testImplementation(libs.assertj)
--- a/kotlin/tests/extra-moshi-test-module/build.gradle.kts
+++ b/kotlin/tests/extra-moshi-test-module/build.gradle.kts
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+plugins {
+  kotlin("jvm")
+}
--- a/kotlin/tests/extra-moshi-test-module/src/main/kotlin/com/squareup/moshi/kotlin/codegen/test/extra/AbstractClassInModuleA.kt
+++ b/kotlin/tests/extra-moshi-test-module/src/main/kotlin/com/squareup/moshi/kotlin/codegen/test/extra/AbstractClassInModuleA.kt
@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen.test.extra
+
+public abstract class AbstractClassInModuleA
--- a/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/DualKotlinTest.kt
+++ b/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/DualKotlinTest.kt
@@ -22,12 +22,13 @@ import com.squareup.moshi.JsonAdapter
 import com.squareup.moshi.JsonAdapter.Factory
 import com.squareup.moshi.JsonClass
 import com.squareup.moshi.JsonDataException
+import com.squareup.moshi.JsonQualifier
 import com.squareup.moshi.Moshi
 import com.squareup.moshi.ToJson
+import com.squareup.moshi.Types
 import com.squareup.moshi.adapter
+import com.squareup.moshi.kotlin.codegen.test.extra.AbstractClassInModuleA
 import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
-import com.squareup.moshi.rawType
-import com.squareup.moshi.supertypeOf
 import org.intellij.lang.annotations.Language
 import org.junit.Assert.fail
 import org.junit.Test
@@ -63,11 +64,11 @@ class DualKotlinTest(useReflection: Boolean) {
          object : Factory {
            override fun create(
              type: Type,
-              annotations: Set<Annotation>,
+              annotations: MutableSet<out Annotation>,
              moshi: Moshi
            ): JsonAdapter<*>? {
              // Prevent falling back to generated adapter lookup
-              val rawType = type.rawType
+              val rawType = Types.getRawType(type)
              val metadataClass = Class.forName("kotlin.Metadata") as Class<out Annotation>
              check(rawType.isEnum || !rawType.isAnnotationPresent(metadataClass)) {
                "Unhandled Kotlin type in reflective test! $rawType"
@@ -248,21 +249,21 @@ class DualKotlinTest(useReflection: Boolean) {
    val hasNonNullConstructorParameterAdapter =
      localMoshi.adapter<HasNonNullConstructorParameter>()
    assertThat(
+      //language=JSON
      hasNonNullConstructorParameterAdapter
-//language=JSON
        .fromJson("{\"a\":null}")
    ).isEqualTo(HasNonNullConstructorParameter("fallback"))

    val hasNullableConstructorParameterAdapter =
      localMoshi.adapter<HasNullableConstructorParameter>()
    assertThat(
+      //language=JSON
      hasNullableConstructorParameterAdapter
-//language=JSON
        .fromJson("{\"a\":null}")
    ).isEqualTo(HasNullableConstructorParameter("fallback"))
+    //language=JSON
    assertThat(
      hasNullableConstructorParameterAdapter
-//language=JSON
        .toJson(HasNullableConstructorParameter(null))
    ).isEqualTo("{\"a\":\"fallback\"}")
  }
@@ -284,7 +285,7 @@ class DualKotlinTest(useReflection: Boolean) {
    assertThat(decoded.a).isEqualTo(null)
  }

-  @Test fun inlineClass() {
+  @Test fun valueClass() {
    val adapter = moshi.adapter<ValueClass>()

    val inline = ValueClass(5)
@@ -297,6 +298,13 @@ class DualKotlinTest(useReflection: Boolean) {
      """{"i":6}"""
    val result = adapter.fromJson(testJson)!!
    assertThat(result.i).isEqualTo(6)
+
+    // TODO doesn't work yet.
+    //  need to invoke the constructor_impl$default static method, invoke constructor with result
+//    val testEmptyJson =
+//      """{}"""
+//    val result2 = adapter.fromJson(testEmptyJson)!!
+//    assertThat(result2.i).isEqualTo(0)
  }

  @JsonClass(generateAdapter = true)
@@ -339,6 +347,50 @@ class DualKotlinTest(useReflection: Boolean) {
  abstract class Asset<A : Asset<A>>
  abstract class AssetMetaData<A : Asset<A>>

+  // Regression test for https://github.com/ZacSweers/MoshiX/issues/125
+  @Test fun selfReferencingTypeVars() {
+    val adapter = moshi.adapter<StringNodeNumberNode>()
+
+    val data = StringNodeNumberNode().also {
+      it.t = StringNodeNumberNode().also {
+        it.text = "child 1"
+      }
+      it.text = "root"
+      it.r = NumberStringNode().also {
+        it.number = 0
+        it.t = NumberStringNode().also {
+          it.number = 1
+        }
+        it.r = StringNodeNumberNode().also {
+          it.text = "grand child 1"
+        }
+      }
+    }
+    assertThat(adapter.toJson(data))
+      //language=JSON
+      .isEqualTo(
+        """
+        {"text":"root","t":{"text":"child 1"},"r":{"number":0,"t":{"number":1},"r":{"text":"grand child 1"}}}
+        """.trimIndent()
+      )
+  }
+
+  @JsonClass(generateAdapter = true)
+  open class Node<T : Node<T, R>, R : Node<R, T>> {
+    var t: T? = null
+    var r: R? = null
+  }
+
+  @JsonClass(generateAdapter = true)
+  class StringNodeNumberNode : Node<StringNodeNumberNode, NumberStringNode>() {
+    var text: String = ""
+  }
+
+  @JsonClass(generateAdapter = true)
+  class NumberStringNode : Node<NumberStringNode, StringNodeNumberNode>() {
+    var number: Int = 0
+  }
+
  // Regression test for https://github.com/square/moshi/issues/968
  @Test fun abstractSuperProperties() {
    val adapter = moshi.adapter<InternalAbstractProperty>()
@@ -447,7 +499,7 @@ class DualKotlinTest(useReflection: Boolean) {
  @Test fun typeAliasUnwrapping() {
    val adapter = moshi
      .newBuilder()
-      .add(supertypeOf<Int>(), moshi.adapter<Int>())
+      .add(Types.supertypeOf(Int::class.javaObjectType), moshi.adapter<Int>())
      .build()
      .adapter<TypeAliasUnwrapping>()

@@ -587,8 +639,7 @@ class DualKotlinTest(useReflection: Boolean) {
  @JsonClass(generateAdapter = true)
  data class OutDeclaration<out T>(val input: T)

-  // Regression test for https://github.com/square/moshi/issues/1244
-  @Test fun backwardReferencingTypeVarsAndIntersectionTypes() {
+  @Test fun intersectionTypes() {
    val adapter = moshi.adapter<IntersectionTypes<IntersectionTypesEnum>>()

    @Language("JSON")
@@ -625,7 +676,7 @@ data class GenericClass<T>(val value: T)
 // Has to be outside since value classes are only allowed on top level
@JvmInline
@JsonClass(generateAdapter = true)
-value class ValueClass(val i: Int)
+value class ValueClass(val i: Int = 0)

 typealias A = Int
 typealias NullableA = A?
@@ -634,3 +685,23 @@ typealias NullableB = B?
 typealias C = NullableA
 typealias D = C
 typealias E = D
+
+// Regression test for enum constants in annotations and array types
+// https://github.com/ZacSweers/MoshiX/issues/103
+@Retention(RUNTIME)
+@JsonQualifier
+annotation class UpperCase(val foo: Array<Foo>)
+
+enum class Foo { BAR }
+
+@JsonClass(generateAdapter = true)
+data class ClassWithQualifier(
+  @UpperCase(foo = [Foo.BAR])
+  val a: Int
+)
+
+// Regression for https://github.com/ZacSweers/MoshiX/issues/120
+@JsonClass(generateAdapter = true)
+data class DataClassInModuleB(
+  val id: String
+) : AbstractClassInModuleA()
--- a/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codegen/MoshiKspTest.kt
+++ b/kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/codegen/MoshiKspTest.kt
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.squareup.moshi.kotlin.codegen
+
+import com.google.common.truth.Truth.assertThat
+import com.squareup.moshi.JsonClass
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.adapter
+import org.junit.Test
+
+// Regression tests specific to Moshi-KSP
+class MoshiKspTest {
+  private val moshi = Moshi.Builder().build()
+
+  // Regression test for https://github.com/ZacSweers/MoshiX/issues/44
+  @Test
+  fun onlyInterfaceSupertypes() {
+    val adapter = moshi.adapter<SimpleImpl>()
+    //language=JSON
+    val json = """{"a":"aValue","b":"bValue"}"""
+    val expected = SimpleImpl("aValue", "bValue")
+    val instance = adapter.fromJson(json)!!
+    assertThat(instance).isEqualTo(expected)
+    val encoded = adapter.toJson(instance)
+    assertThat(encoded).isEqualTo(json)
+  }
+
+  interface SimpleInterface {
+    val a: String
+  }
+
+  // NOTE the Any() superclass is important to test that we're detecting the farthest parent class
+  // correct.y
+  @JsonClass(generateAdapter = true)
+  data class SimpleImpl(override val a: String, val b: String) : Any(), SimpleInterface
+}
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -31,5 +31,6 @@ include(":examples")
 include(":kotlin:reflect")
 include(":kotlin:codegen")
 include(":kotlin:tests")
+include(":kotlin:tests:extra-moshi-test-module")

 enableFeaturePreview("VERSION_CATALOGS")
				`@@ -0,0 +1 @@`
				`com.squareup.moshi.kotlin.codegen.apt.JsonClassCodegenProcessor,ISOLATING`