Change DelegateKey to use AnnotationSpec instead of AnnotationMirror

AnnotationSpec implements equals() in the way we need, but
AnnotationMirror doesn't. As a consequence this fixes a problem
where we were generating redundant adapters.

Closes: https://github.com/square/moshi/issues/563

kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/AdapterGenerator.kt

@@ -135,7 +135,7 @@ internal class AdapterGenerator(
     result.addProperty(optionsProperty)
     for (uniqueAdapter in propertyList.distinctBy { it.delegateKey }) {
       result.addProperty(uniqueAdapter.delegateKey.generateProperty(
-          nameAllocator, typeRenderer, moshiParam, messager))
+          nameAllocator, typeRenderer, moshiParam))
     }
 
     result.addFunction(generateToStringFun())

kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/DelegateKey.kt

@@ -15,9 +15,7 @@
  */
 package com.squareup.moshi.kotlin.codegen
 
-import com.google.auto.common.MoreTypes
 import com.squareup.kotlinpoet.AnnotationSpec
-import com.squareup.kotlinpoet.AnnotationSpec.UseSiteTarget.FIELD
 import com.squareup.kotlinpoet.ClassName
 import com.squareup.kotlinpoet.CodeBlock
 import com.squareup.kotlinpoet.KModifier
@@ -33,16 +31,11 @@ import com.squareup.kotlinpoet.asClassName
 import com.squareup.kotlinpoet.asTypeName
 import com.squareup.moshi.JsonAdapter
 import com.squareup.moshi.Types
-import java.lang.annotation.ElementType
-import java.lang.annotation.RetentionPolicy
-import javax.annotation.processing.Messager
-import javax.lang.model.element.AnnotationMirror
-import javax.tools.Diagnostic.Kind.ERROR
 
 /** A JsonAdapter that can be used to encode and decode a particular field. */
 internal data class DelegateKey(
   private val type: TypeName,
-  private val jsonQualifiers: Set<AnnotationMirror>
+  private val jsonQualifiers: List<AnnotationSpec>
 ) {
   val nullable get() = type.nullable
 
@@ -50,36 +43,17 @@ internal data class DelegateKey(
   fun generateProperty(
     nameAllocator: NameAllocator,
     typeRenderer: TypeRenderer,
-    moshiParameter: ParameterSpec,
-    messager: Messager): PropertySpec {
-    fun AnnotationMirror.validate(): AnnotationMirror {
-      // Check java types since that covers both java and kotlin annotations
-      val annotationElement = MoreTypes.asTypeElement(annotationType)
-      annotationElement.getAnnotation(java.lang.annotation.Retention::class.java)?.let {
-        if (it.value != RetentionPolicy.RUNTIME) {
-          messager.printMessage(ERROR, "JsonQualifier " +
-              "@${MoreTypes.asTypeElement(annotationType).simpleName} must have RUNTIME retention")
-        }
-      }
-      annotationElement.getAnnotation(java.lang.annotation.Target::class.java)?.let {
-        if (ElementType.FIELD !in it.value) {
-          messager.printMessage(ERROR, "JsonQualifier " +
-              "@${MoreTypes.asTypeElement(annotationType).simpleName} must support FIELD target")
-        }
-      }
-      return this
-    }
-    jsonQualifiers.forEach { it.validate() }
+    moshiParameter: ParameterSpec
+  ): PropertySpec {
     val qualifierNames = jsonQualifiers.joinToString("") {
-      "At${it.annotationType.asElement().simpleName}"
+      "At${(it.type as ClassName).simpleName}"
     }
     val adapterName = nameAllocator.newName(
         "${type.toVariableName().decapitalize()}${qualifierNames}Adapter", this)
 
     val adapterTypeName = JsonAdapter::class.asClassName().parameterizedBy(type)
-    val qualifiers = jsonQualifiers
     val standardArgs = arrayOf(moshiParameter,
-        if (type is ClassName && qualifiers.isEmpty()) {
+        if (type is ClassName && jsonQualifiers.isEmpty()) {
           ""
         } else {
           CodeBlock.of("<%T>", type)
@@ -87,7 +61,7 @@ internal data class DelegateKey(
         typeRenderer.render(type))
     val standardArgsSize = standardArgs.size + 1
     val (initializerString, args) = when {
-      qualifiers.isEmpty() -> "" to emptyArray()
+      jsonQualifiers.isEmpty() -> "" to emptyArray()
       else -> {
         ", %${standardArgsSize}T.getFieldJsonQualifierAnnotations(javaClass, " +
             "%${standardArgsSize + 1}S)" to arrayOf(Types::class.asTypeName(), adapterName)
@@ -98,9 +72,7 @@ internal data class DelegateKey(
     val nullModifier = if (nullable) ".nullSafe()" else ".nonNull()"
 
     return PropertySpec.builder(adapterName, adapterTypeName, KModifier.PRIVATE)
-        .addAnnotations(qualifiers.map {
-          AnnotationSpec.get(it).toBuilder().useSiteTarget(FIELD).build()
-        })
+        .addAnnotations(jsonQualifiers)
         .initializer("%1N.adapter%2L(%3L$initializerString)$nullModifier", *finalArgs)
         .build()
   }

kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/PropertyGenerator.kt

@@ -20,8 +20,10 @@ import com.squareup.kotlinpoet.NameAllocator
 import com.squareup.kotlinpoet.PropertySpec
 
 /** Generates functions to encode and decode a property as JSON. */
-internal class PropertyGenerator(val target: TargetProperty) {
-  val delegateKey = target.delegateKey()
+internal class PropertyGenerator(
+  val target: TargetProperty,
+  val delegateKey: DelegateKey
+) {
   val name = target.name
   val jsonName = target.jsonName()
   val hasDefault = target.hasDefault

kotlin/codegen/src/main/java/com/squareup/moshi/kotlin/codegen/TargetProperty.kt

@@ -16,6 +16,8 @@
 package com.squareup.moshi.kotlin.codegen
 
 import com.google.auto.common.AnnotationMirrors
+import com.google.auto.common.MoreTypes
+import com.squareup.kotlinpoet.AnnotationSpec
 import com.squareup.kotlinpoet.TypeName
 import com.squareup.moshi.Json
 import com.squareup.moshi.JsonQualifier
@@ -26,11 +28,16 @@ import me.eugeniomarletti.kotlin.metadata.shadow.metadata.ProtoBuf.Visibility.IN
 import me.eugeniomarletti.kotlin.metadata.shadow.metadata.ProtoBuf.Visibility.PROTECTED
 import me.eugeniomarletti.kotlin.metadata.shadow.metadata.ProtoBuf.Visibility.PUBLIC
 import me.eugeniomarletti.kotlin.metadata.visibility
+import java.lang.annotation.ElementType
+import java.lang.annotation.Retention
+import java.lang.annotation.RetentionPolicy
+import java.lang.annotation.Target
 import javax.annotation.processing.Messager
 import javax.lang.model.element.AnnotationMirror
 import javax.lang.model.element.Element
 import javax.lang.model.element.ExecutableElement
 import javax.lang.model.element.Modifier
+import javax.lang.model.element.Name
 import javax.lang.model.element.VariableElement
 import javax.tools.Diagnostic
 
@@ -85,10 +92,32 @@ internal data class TargetProperty(
       return null // This property is not settable. Ignore it.
     }
 
-    return PropertyGenerator(this)
-  }
+    val jsonQualifierMirrors = jsonQualifiers()
+    for (jsonQualifier in jsonQualifierMirrors) {
+      // Check Java types since that covers both Java and Kotlin annotations.
+      val annotationElement = MoreTypes.asTypeElement(jsonQualifier.annotationType)
+      annotationElement.getAnnotation(Retention::class.java)?.let {
+        if (it.value != RetentionPolicy.RUNTIME) {
+          messager.printMessage(Diagnostic.Kind.ERROR,
+              "JsonQualifier @${jsonQualifier.simpleName} must have RUNTIME retention")
+        }
+      }
+      annotationElement.getAnnotation(Target::class.java)?.let {
+        if (ElementType.FIELD !in it.value) {
+          messager.printMessage(Diagnostic.Kind.ERROR,
+              "JsonQualifier @${jsonQualifier.simpleName} must support FIELD target")
+        }
+      }
+    }
 
-  fun delegateKey() = DelegateKey(type, jsonQualifiers())
+    val jsonQualifierSpecs = jsonQualifierMirrors.map {
+      AnnotationSpec.get(it).toBuilder()
+          .useSiteTarget(AnnotationSpec.UseSiteTarget.FIELD)
+          .build()
+    }
+
+    return PropertyGenerator(this, DelegateKey(type, jsonQualifierSpecs))
+  }
 
   /** Returns the JsonQualifiers on the field and parameter of this property. */
   private fun jsonQualifiers(): Set<AnnotationMirror> {
@@ -131,5 +160,8 @@ internal data class TargetProperty(
       return getAnnotation(Json::class.java)?.name?.replace("$", "\\$")
     }
 
+  private val AnnotationMirror.simpleName: Name
+    get() = MoreTypes.asTypeElement(annotationType).simpleName!!
+
   override fun toString() = name
 }