Build proper modifier list stubs for 'SuspendFunction$n<...>' types.

core/descriptors/src/org/jetbrains/kotlin/builtins/functionTypes.kt

@@ -24,6 +24,7 @@ import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptorImpl
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationsImpl
+import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqNameUnsafe
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.constants.ConstantValueFactory
@@ -72,6 +73,12 @@ val KotlinType.isBuiltinFunctionalType: Boolean
                kind == FunctionClassDescriptor.Kind.SuspendFunction
     }
 
+fun isBuiltinFunctionClass(classId: ClassId): Boolean {
+    val kind = classId.asSingleFqName().toUnsafe().getFunctionalClassKind()
+    return kind == FunctionClassDescriptor.Kind.Function ||
+           kind == FunctionClassDescriptor.Kind.SuspendFunction
+}
+
 val KotlinType.isNonExtensionFunctionType: Boolean
     get() = isBuiltinFunctionalType && !isTypeAnnotatedWithExtensionFunctionType
 
@@ -99,8 +106,12 @@ fun DeclarationDescriptor.getFunctionalClassKind(): FunctionClassDescriptor.Kind
     if (this !is ClassDescriptor) return null
 
     val fqNameUnsafe = this.fqNameUnsafe
-    if (!fqNameUnsafe.isSafe || fqNameUnsafe.isRoot) return null
-    val fqName = fqNameUnsafe.toSafe()
+    return fqNameUnsafe.getFunctionalClassKind()
+}
+
+fun FqNameUnsafe.getFunctionalClassKind(): FunctionClassDescriptor.Kind? {
+    if (!isSafe || isRoot) return null
+    val fqName = toSafe()
 
     return BuiltInFictitiousFunctionClassFactory.getFunctionalClassKind(fqName.shortName().asString(), fqName.parent())
 }

idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/stubBuilder/TypeClsStubBuilder.kt

@@ -19,7 +19,9 @@ package org.jetbrains.kotlin.idea.decompiler.stubBuilder
 import com.intellij.psi.PsiElement
 import com.intellij.psi.stubs.StubElement
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
-import org.jetbrains.kotlin.builtins.isNumberedFunctionClassFqName
+import org.jetbrains.kotlin.builtins.functions.FunctionClassDescriptor
+import org.jetbrains.kotlin.builtins.getFunctionalClassKind
+import org.jetbrains.kotlin.builtins.isBuiltinFunctionClass
 import org.jetbrains.kotlin.lexer.KtModifierKeywordToken
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.load.java.ANNOTATIONS_COPIED_TO_TYPES
@@ -89,7 +91,7 @@ class TypeClsStubBuilder(private val c: ClsStubBuilderContext) {
         }
 
         val classId = c.nameResolver.getClassId(if (type.hasClassName()) type.className else type.typeAliasName)
-        val shouldBuildAsFunctionType = isNumberedFunctionClassFqName(classId.asSingleFqName().toUnsafe())
+        val shouldBuildAsFunctionType = isBuiltinFunctionClass(classId)
                                         && type.argumentList.none { it.projection == Projection.STAR }
         if (shouldBuildAsFunctionType) {
             val (extensionAnnotations, notExtensionAnnotations) =
@@ -114,13 +116,24 @@ class TypeClsStubBuilder(private val c: ClsStubBuilderContext) {
     }
 
     private fun createTypeAnnotationStubs(parent: KotlinStubBaseImpl<*>, type: Type, annotations: List<ClassId>) {
-        // TODO Calculate type modifiers mask, see 'ModifierMaskUtils.computeMask'
-        val typeModifiersMask = 0
-        if (annotations.isEmpty()) return
+        val typeModifiers = getTypeModifiersAsWritten(type)
+        if (annotations.isEmpty() && typeModifiers.isEmpty()) return
+        val typeModifiersMask = ModifierMaskUtils.computeMask { it in typeModifiers }
         val modifiersList = KotlinModifierListStubImpl(parent, typeModifiersMask, KtStubElementTypes.MODIFIER_LIST)
         createAnnotationStubs(annotations, modifiersList)
     }
 
+    private fun getTypeModifiersAsWritten(type: Type): Set<KtModifierKeywordToken> {
+        val result = hashSetOf<KtModifierKeywordToken>()
+        val classId = c.nameResolver.getClassId(if (type.hasClassName()) type.className else type.typeAliasName)
+
+        if (classId.asSingleFqName().toUnsafe().getFunctionalClassKind() == FunctionClassDescriptor.Kind.SuspendFunction) {
+            result.add(KtTokens.SUSPEND_KEYWORD)
+        }
+
+        return result
+    }
+
     private fun createTypeArgumentListStub(typeStub: KotlinUserTypeStub, typeArgumentProtoList: List<Type.Argument>) {
         if (typeArgumentProtoList.isEmpty()) {
             return

idea/testData/decompiler/stubBuilder/TypeModifiers/TypeModifiers.kt

@@ -1,4 +1,6 @@
 public class TypeModifiers {
+    val function: () -> Unit = null!!
+
     val suspendFunction: suspend () -> Unit = null!!
 
     val suspendExtFunction: suspend Any.() -> Unit = null!!

idea/testData/decompiler/stubBuilder/TypeModifiers/TypeModifiers.txt

@@ -7,12 +7,23 @@ PsiJetFileStubImpl[package=]
       MODIFIER_LIST[public]
       VALUE_PARAMETER_LIST
     CLASS_BODY
+      PROPERTY[fqName=TypeModifiers.function, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=function]
+        MODIFIER_LIST[public final]
+        TYPE_REFERENCE
+          FUNCTION_TYPE
+            VALUE_PARAMETER_LIST
+            TYPE_REFERENCE
+              USER_TYPE
+                USER_TYPE
+                  REFERENCE_EXPRESSION[referencedName=kotlin]
+                REFERENCE_EXPRESSION[referencedName=Unit]
       PROPERTY[fqName=TypeModifiers.functionOnSuspendFunction, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=functionOnSuspendFunction]
         MODIFIER_LIST[public final]
         TYPE_REFERENCE
           FUNCTION_TYPE
             FUNCTION_TYPE_RECEIVER
               TYPE_REFERENCE
+                MODIFIER_LIST[suspend]
                 FUNCTION_TYPE
                   VALUE_PARAMETER_LIST
                   TYPE_REFERENCE
@@ -29,6 +40,7 @@ PsiJetFileStubImpl[package=]
       PROPERTY[fqName=TypeModifiers.suspendExtFunction, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=suspendExtFunction]
         MODIFIER_LIST[public final]
         TYPE_REFERENCE
+          MODIFIER_LIST[suspend]
           FUNCTION_TYPE
             FUNCTION_TYPE_RECEIVER
               TYPE_REFERENCE
@@ -45,6 +57,7 @@ PsiJetFileStubImpl[package=]
       PROPERTY[fqName=TypeModifiers.suspendFunction, hasDelegate=false, hasDelegateExpression=false, hasInitializer=false, hasReturnTypeRef=true, isExtension=false, isTopLevel=false, isVar=false, name=suspendFunction]
         MODIFIER_LIST[public final]
         TYPE_REFERENCE
+          MODIFIER_LIST[suspend]
           FUNCTION_TYPE
             VALUE_PARAMETER_LIST
             TYPE_REFERENCE