Allow to have all parameters with default values in actual annotation

#KT-19656 In Progress

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
+ * Copyright 2010-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -131,7 +131,9 @@ object ExpectedActualDeclarationChecker : DeclarationChecker {
         if (!hasExpectedModifier) {
             if (Compatible !in compatibility) return
 
-            if (checkExpected) {
+            // we suppress error, because annotation classes can only have one constructor and it's a 100% boilerplate
+            // to require every annotation constructor with additional parameters with default values be marked with the `actual` modifier
+            if (checkExpected && !descriptor.isAnnotationConstructor()) {
                 diagnosticHolder.report(Errors.ACTUAL_MISSING.on(reportOn))
             }
         }
@@ -362,7 +364,9 @@ object ExpectedActualDeclarationChecker : DeclarationChecker {
 
         val aParams = a.valueParameters
         val bParams = b.valueParameters
-        if (aParams.size != bParams.size) return Incompatible.ParameterCount
+        if (!valueParametersCountCompatible(a, b, aParams, bParams)) {
+            return Incompatible.ParameterCount
+        }
 
         val aTypeParams = a.typeParameters
         val bTypeParams = b.typeParameters
@@ -401,6 +405,23 @@ object ExpectedActualDeclarationChecker : DeclarationChecker {
         return Compatible
     }
 
+    private fun valueParametersCountCompatible(
+            a: CallableMemberDescriptor,
+            b: CallableMemberDescriptor,
+            aParams: List<ValueParameterDescriptor>,
+            bParams: List<ValueParameterDescriptor>
+    ): Boolean {
+        if (aParams.size == bParams.size) return true
+
+        return if (a.isAnnotationConstructor() && b.isAnnotationConstructor())
+            aParams.isEmpty() && bParams.all { it.declaresDefaultValue() }
+        else
+            false
+    }
+
+    private fun MemberDescriptor.isAnnotationConstructor(): Boolean =
+            this is ConstructorDescriptor && DescriptorUtils.isAnnotationClass(this.constructedClass)
+
     private fun areCompatibleTypes(a: KotlinType?, b: KotlinType?, platformModule: ModuleDescriptor): Boolean {
         if (a == null) return b == null
         if (b == null) return false

compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDefaultValuesInAnnotationViaTypealias.kt

@@ -0,0 +1,33 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect annotation class Foo1
+expect annotation class Foo2
+expect annotation class Foo3
+expect annotation class Foo4
+
+// MODULE: m2-jvm(m1-common)
+
+// FILE: Bar1.java
+
+public @interface Bar1 {
+    String value() default "";
+}
+
+// FILE: Bar2.java
+
+public @interface Bar2 {
+    String value() default "";
+    String path();
+}
+
+// FILE: jvm.kt
+
+actual typealias Foo1 = Bar1
+
+<!NO_ACTUAL_CLASS_MEMBER_FOR_EXPECTED_CLASS!>actual typealias Foo4 = Bar2<!>
+
+actual annotation class Foo2(val p: String = "default")
+
+actual annotation class Foo3(val a: String = "a", val b: String = "b")

compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDefaultValuesInAnnotationViaTypealias.txt

@@ -0,0 +1,70 @@
+// -- Module: <m1-common> --
+package
+
+public final expect annotation class Foo1 : kotlin.Annotation {
+    public constructor Foo1()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final expect annotation class Foo2 : kotlin.Annotation {
+    public constructor Foo2()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final expect annotation class Foo3 : kotlin.Annotation {
+    public constructor Foo3()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final expect annotation class Foo4 : kotlin.Annotation {
+    public constructor Foo4()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+
+// -- Module: <m2-jvm> --
+package
+
+public final annotation class Bar1 : kotlin.Annotation {
+    public constructor Bar1(/*0*/ value: kotlin.String = ...)
+    public final val value: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final annotation class Bar2 : kotlin.Annotation {
+    public constructor Bar2(/*0*/ value: kotlin.String = ..., /*1*/ path: kotlin.String)
+    public final val path: kotlin.String
+    public final val value: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final actual annotation class Foo2 : kotlin.Annotation {
+    public constructor Foo2(/*0*/ p: kotlin.String = ...)
+    public final val p: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final actual annotation class Foo3 : kotlin.Annotation {
+    public constructor Foo3(/*0*/ a: kotlin.String = ..., /*1*/ b: kotlin.String = ...)
+    public final val a: kotlin.String
+    public final val b: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+public typealias Foo1 = Bar1
+public typealias Foo4 = Bar2

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -13934,6 +13934,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)
             public static class HeaderClass extends AbstractDiagnosticsTest {
+                @TestMetadata("actualClassWithDefaultValuesInAnnotationViaTypealias.kt")
+                public void testActualClassWithDefaultValuesInAnnotationViaTypealias() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDefaultValuesInAnnotationViaTypealias.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("actualMissing.kt")
                 public void testActualMissing() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/headerClass/actualMissing.kt");

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -13934,6 +13934,12 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)
             public static class HeaderClass extends AbstractDiagnosticsUsingJavacTest {
+                @TestMetadata("actualClassWithDefaultValuesInAnnotationViaTypealias.kt")
+                public void testActualClassWithDefaultValuesInAnnotationViaTypealias() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDefaultValuesInAnnotationViaTypealias.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("actualMissing.kt")
                 public void testActualMissing() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/headerClass/actualMissing.kt");