Combine type annotations for arguments of type aliases.

compiler/frontend/src/org/jetbrains/kotlin/resolve/TypeAliasExpander.kt

@@ -50,7 +50,7 @@ class TypeAliasExpander(
             "Type alias expansion: result for ${typeAliasExpansion.descriptor} is ${expandedProjection.projectionKind}, should be invariant"
         }
 
-        val expandedTypeWithExtraAnnotations = combineAnnotations(expandedType, annotations)
+        val expandedTypeWithExtraAnnotations = expandedType.combineAnnotations(annotations)
 
         return if (withAbbreviatedType)
             expandedTypeWithExtraAnnotations.withAbbreviation(typeAliasExpansion.createAbbreviation(underlyingProjection, annotations))
@@ -58,8 +58,8 @@ class TypeAliasExpander(
             expandedTypeWithExtraAnnotations
     }
 
-    private fun combineAnnotations(type: SimpleType, annotations: Annotations): SimpleType {
-        val existingAnnotationTypes = type.annotations.getAllAnnotations().mapTo(hashSetOf<KotlinType>()) { it.annotation.type }
+    private fun SimpleType.combineAnnotations(annotations: Annotations): SimpleType {
+        val existingAnnotationTypes = this.annotations.getAllAnnotations().mapTo(hashSetOf<KotlinType>()) { it.annotation.type }
 
         for (annotation in annotations) {
             if (annotation.type in existingAnnotationTypes) {
@@ -67,7 +67,7 @@ class TypeAliasExpander(
             }
         }
 
-        return type.replace(newAnnotations = CompositeAnnotations(listOf(annotations, type.annotations)))
+        return replace(newAnnotations = CompositeAnnotations(listOf(annotations, this.annotations)))
     }
 
     private fun TypeAliasExpansion.createAbbreviation(originalProjection: TypeProjection, annotations: Annotations) =
@@ -85,6 +85,7 @@ class TypeAliasExpander(
             typeParameterDescriptor: TypeParameterDescriptor?,
             recursionDepth: Int
     ): TypeProjection {
+        // TODO refactor TypeSubstitutor to introduce custom diagnostics
         assertRecursionDepth(recursionDepth, typeAliasExpansion.descriptor)
 
         if (underlyingProjection.isStarProjection) return TypeUtils.makeStarProjection(typeParameterDescriptor!!)
@@ -100,13 +101,15 @@ class TypeAliasExpander(
         val argumentVariance = argument.projectionKind
         val underlyingVariance = underlyingProjection.projectionKind
 
+        val argumentType = argument.type as? SimpleType ?: throw AssertionError("Non-simple type in type alias argument: $argument")
+
         val substitutionVariance =
                 when {
                     underlyingVariance == argumentVariance -> argumentVariance
                     underlyingVariance == Variance.INVARIANT -> argumentVariance
                     argumentVariance == Variance.INVARIANT -> underlyingVariance
                     else -> {
-                        reportStrategy.conflictingProjection(typeAliasExpansion.descriptor, typeParameterDescriptor, argument.type)
+                        reportStrategy.conflictingProjection(typeAliasExpansion.descriptor, typeParameterDescriptor, argumentType)
                         argumentVariance
                     }
                 }
@@ -118,12 +121,13 @@ class TypeAliasExpander(
                     parameterVariance == Variance.INVARIANT -> substitutionVariance
                     substitutionVariance == Variance.INVARIANT -> Variance.INVARIANT
                     else -> {
-                        reportStrategy.conflictingProjection(typeAliasExpansion.descriptor, typeParameterDescriptor, argument.type)
+                        reportStrategy.conflictingProjection(typeAliasExpansion.descriptor, typeParameterDescriptor, argumentType)
                         substitutionVariance
                     }
                 }
 
-        val substitutedType = TypeUtils.makeNullableIfNeeded(argument.type, underlyingType.isMarkedNullable)
+        val substitutedType = TypeUtils.makeNullableIfNeeded(argumentType, underlyingType.isMarkedNullable)
+                .combineAnnotations(underlyingType.annotations)
 
         return TypeProjectionImpl(resultingVariance, substitutedType)
     }

compiler/frontend/src/org/jetbrains/kotlin/resolve/TypeAliasExpansion.kt

@@ -16,14 +16,10 @@
 
 package org.jetbrains.kotlin.resolve
 
-import org.jetbrains.kotlin.descriptors.ClassifierDescriptor
 import org.jetbrains.kotlin.descriptors.TypeAliasDescriptor
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
-import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.TypeConstructor
 import org.jetbrains.kotlin.types.TypeProjection
-import org.jetbrains.kotlin.types.TypeUtils
-import org.jetbrains.kotlin.types.typeUtil.contains
 
 class TypeAliasExpansion private constructor(
         val parent: TypeAliasExpansion?,

compiler/testData/diagnostics/tests/typealias/parameterSubstitution.txt

@@ -1,7 +1,7 @@
 package
 
 public val ca1: CA<kotlin.Int> /* = C<kotlin.Int> */
-public val ca2: CA<CA<kotlin.Int> /* = C<kotlin.Int> */> /* = C<CA<kotlin.Int> /* = C<kotlin.Int> */> */
+public val ca2: CA<CA<kotlin.Int> /* = C<kotlin.Int> */> /* = C<C<kotlin.Int>> */
 public val ca3: CA<C<kotlin.Int>> /* = C<C<kotlin.Int>> */
 public val ca4: CA<kotlin.Int?> /* = C<kotlin.Int?> */
 

compiler/testData/diagnostics/tests/typealias/typeAliasForProjectionInSuperInterfaces.txt

@@ -34,7 +34,7 @@ public final class Test4 : IT<*> /* = I<*> */ {
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
 
-public final class Test5 : IT<IT<*> /* = I<*> */> /* = I<IT<*> /* = I<*> */> */ {
+public final class Test5 : IT<IT<*> /* = I<*> */> /* = I<I<*>> */ {
     public constructor Test5()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int

compiler/testData/diagnostics/tests/typealias/typealiasRhsAnnotationsInArguments.kt

@@ -0,0 +1,11 @@
+@Target(AnnotationTarget.TYPE)
+annotation class Ann1
+
+@Target(AnnotationTarget.TYPE)
+annotation class Ann2
+
+class C<T>
+
+typealias CA<T> = C<@Ann1 T>
+
+fun test(x: CA<@Ann2 Int>) = x

compiler/testData/diagnostics/tests/typealias/typealiasRhsAnnotationsInArguments.txt

@@ -0,0 +1,25 @@
+package
+
+public fun test(/*0*/ x: CA<@Ann2 kotlin.Int> /* = C<@Ann1 @Ann2 kotlin.Int> */): CA<@Ann2 kotlin.Int> /* = C<@Ann1 @Ann2 kotlin.Int> */
+
+@kotlin.annotation.Target(allowedTargets = {AnnotationTarget.TYPE}) public final annotation class Ann1 : kotlin.Annotation {
+    public constructor Ann1()
+    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
+}
+
+@kotlin.annotation.Target(allowedTargets = {AnnotationTarget.TYPE}) public final annotation class Ann2 : kotlin.Annotation {
+    public constructor Ann2()
+    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 class C</*0*/ T> {
+    public constructor C</*0*/ T>()
+    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 CA</*0*/ T>  = C<@Ann1 T>

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

@@ -21286,6 +21286,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("typealiasRhsAnnotationsInArguments.kt")
+            public void testTypealiasRhsAnnotationsInArguments() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/typealias/typealiasRhsAnnotationsInArguments.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("typealiasRhsRepeatedAnnotations.kt")
             public void testTypealiasRhsRepeatedAnnotations() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/typealias/typealiasRhsRepeatedAnnotations.kt");