FIR: add type alias descriptors

compiler/fir/resolve/src/org/jetbrains/kotlin/descriptors/ConeClassDescriptorImpl.kt

@@ -17,5 +17,4 @@ class ConeClassDescriptorImpl(
     override val fqName: ClassId,
     override val superTypes: List<ConeKotlinType>,
     override val nestedClassifiers: List<ConeClassifierDescriptor>
-) : ConeClassDescriptor, AbstractFirBasedDescriptor<FirResolvedClass>() {
-}
+) : ConeClassDescriptor, AbstractFirBasedDescriptor<FirResolvedClass>()

compiler/fir/resolve/src/org/jetbrains/kotlin/descriptors/ConeTypeAliasDescriptorImpl.kt

@@ -0,0 +1,18 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.descriptors
+
+import org.jetbrains.kotlin.fir.declarations.FirResolvedTypeAlias
+import org.jetbrains.kotlin.fir.descriptors.ConeTypeAliasDescriptor
+import org.jetbrains.kotlin.fir.descriptors.ConeTypeParameterDescriptor
+import org.jetbrains.kotlin.fir.types.ConeKotlinType
+import org.jetbrains.kotlin.name.ClassId
+
+class ConeTypeAliasDescriptorImpl(
+    override val typeParameters: List<ConeTypeParameterDescriptor>,
+    override val fqName: ClassId,
+    override val expandedType: ConeKotlinType
+) : ConeTypeAliasDescriptor, AbstractFirBasedDescriptor<FirResolvedTypeAlias>()

compiler/fir/resolve/src/org/jetbrains/kotlin/descriptors/FirClassifierResolveTransformer.kt

@@ -7,11 +7,9 @@ package org.jetbrains.kotlin.descriptors
 
 import org.jetbrains.kotlin.fir.FirDescriptorOwner
 import org.jetbrains.kotlin.fir.FirElement
-import org.jetbrains.kotlin.fir.declarations.FirClass
-import org.jetbrains.kotlin.fir.declarations.FirDeclaration
-import org.jetbrains.kotlin.fir.declarations.FirFile
-import org.jetbrains.kotlin.fir.declarations.FirResolvedClass
+import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.impl.FirResolvedClassImpl
+import org.jetbrains.kotlin.fir.declarations.impl.FirResolvedTypeAliasImpl
 import org.jetbrains.kotlin.fir.descriptors.ConeClassifierDescriptor
 import org.jetbrains.kotlin.fir.descriptors.ConeTypeParameterDescriptor
 import org.jetbrains.kotlin.fir.types.FirResolvedType
@@ -66,4 +64,26 @@ class FirClassifierResolveTransformer : FirTransformer<Nothing?>() {
     override fun transformResolvedClass(resolvedClass: FirResolvedClass, data: Nothing?): CompositeTransformResult<FirDeclaration> {
         return resolvedClass.compose()
     }
+
+    override fun transformTypeAlias(typeAlias: FirTypeAlias, data: Nothing?): CompositeTransformResult<FirDeclaration> {
+        typeAlias.transformChildren(this, data)
+        val expandedType = (typeAlias.expandedType as FirResolvedType).type
+        val typeParameters =
+            typeAlias.typeParameters.filterIsInstance<FirDescriptorOwner<*>>().mapNotNull { it.descriptor as? ConeTypeParameterDescriptor }
+
+        val descriptor = ConeTypeAliasDescriptorImpl(
+            typeParameters,
+            ClassId(packageFqName, className.child(typeAlias.name), false),
+            expandedType
+        )
+
+        return FirResolvedTypeAliasImpl(typeAlias, descriptor).compose()
+    }
+
+    override fun transformResolvedTypeAlias(
+        resolvedTypeAlias: FirResolvedTypeAlias,
+        data: Nothing?
+    ): CompositeTransformResult<FirDeclaration> {
+        return resolvedTypeAlias.compose()
+    }
 }

compiler/fir/resolve/src/org/jetbrains/kotlin/descriptors/FirTypeResolveTransformer.kt

@@ -143,7 +143,7 @@ class FirTypeResolveTransformer(val superTypesOnly: Boolean = false) : FirTransf
                         classifier.superTypes.any { it.accept(this, data) }
                     }
                 }
-                is FirTypeAlias -> classifier.abbreviatedType.accept(this, data)
+                is FirTypeAlias -> classifier.expandedType.accept(this, data)
             }
             return true
         }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/impl/FirQualifierResolverImpl.kt

@@ -48,7 +48,7 @@ class FirQualifierResolverImpl(val session: FirSession) : FirQualifierResolver {
                 ConeAbbreviatedTypeImpl(
                     abbreviationFqName = fqName,
                     typeArguments = parts.toTypeProjections(),
-                    directExpansion = (this.abbreviatedType as FirResolvedType).type
+                    directExpansion = (this.expandedType as FirResolvedType).type
                 )
 
             }