Corrected Kotlin codegen to properly handle top-level functions

Author: volivan239

utbot-core/src/main/kotlin/org/utbot/common/KClassUtil.kt

@@ -2,7 +2,6 @@ package org.utbot.common
 
 import java.lang.reflect.InvocationTargetException
 import java.lang.reflect.Method
-import kotlin.reflect.KClass
 
 val Class<*>.nameOfPackage: String get() = `package`?.name?:""
 
@@ -12,8 +11,5 @@ fun Method.invokeCatching(obj: Any?, args: List<Any?>) = try {
     Result.failure<Nothing>(e.targetException)
 }
 
-val KClass<*>.allNestedClasses: List<KClass<*>>
-    get() = listOf(this) + nestedClasses.flatMap { it.allNestedClasses }
-
 val Class<*>.allNestedClasses: List<Class<*>>
     get() = listOf(this) + this.declaredClasses.flatMap { it.declaredClasses.toList() }

utbot-framework-api/src/main/kotlin/org/utbot/framework/plugin/api/util/IdUtil.kt

@@ -25,6 +25,7 @@ import kotlin.reflect.KClass
 import kotlin.reflect.KFunction
 import kotlin.reflect.KProperty
 import kotlin.reflect.full.instanceParameter
+import kotlin.reflect.jvm.internal.impl.load.kotlin.header.KotlinClassHeader
 import kotlin.reflect.jvm.javaConstructor
 import kotlin.reflect.jvm.javaField
 import kotlin.reflect.jvm.javaGetter
@@ -178,6 +179,14 @@ val ClassId.isDoubleType: Boolean
 val ClassId.isClassType: Boolean
     get() = this == classClassId
 
+/**
+ * Checks if the class is a Kotlin class with kind File (see [Metadata.kind] for more details)
+ */
+val ClassId.isKotlinFile: Boolean
+    get() = jClass.annotations.filterIsInstance<Metadata>().singleOrNull()?.let {
+        KotlinClassHeader.Kind.getById(it.kind) == KotlinClassHeader.Kind.FILE_FACADE
+    } ?: false
+
 val voidClassId = ClassId("void")
 val booleanClassId = ClassId("boolean")
 val byteClassId = ClassId("byte")

utbot-framework/src/main/kotlin/org/utbot/framework/codegen/model/visitor/CgAbstractRenderer.kt

@@ -131,8 +131,10 @@ internal abstract class CgAbstractRenderer(
         }
     }
 
+    protected abstract val ClassId.shouldBeOmittedWhenUsedAsCaller: Boolean
+
     private val MethodId.accessibleByName: Boolean
-        get() = (context.shouldOptimizeImports && this in context.importedStaticMethods) || classId == context.generatedClass
+        get() = (context.shouldOptimizeImports && this in context.importedStaticMethods) || classId == context.generatedClass || classId.shouldBeOmittedWhenUsedAsCaller
 
     override fun visit(element: CgElement) {
         val error =
@@ -654,8 +656,10 @@ internal abstract class CgAbstractRenderer(
     }
 
     override fun visit(element: CgStaticFieldAccess) {
-        print(element.declaringClass.asString())
-        print(".")
+        if (!element.declaringClass.shouldBeOmittedWhenUsedAsCaller) {
+            print(element.declaringClass.asString())
+            print(".")
+        }
         print(element.fieldName)
     }
 

utbot-framework/src/main/kotlin/org/utbot/framework/codegen/model/visitor/CgJavaRenderer.kt

@@ -60,6 +60,9 @@ internal class CgJavaRenderer(context: CgRendererContext, printer: CgPrinter = C
 
     override val langPackage: String = "java.lang"
 
+    override val ClassId.shouldBeOmittedWhenUsedAsCaller: Boolean
+        get() = false
+
     override fun visit(element: AbstractCgClass<*>) {
         for (annotation in element.annotations) {
             annotation.accept(this)

utbot-framework/src/main/kotlin/org/utbot/framework/codegen/model/visitor/CgKotlinRenderer.kt

@@ -53,6 +53,7 @@ import org.utbot.framework.plugin.api.TypeParameters
 import org.utbot.framework.plugin.api.WildcardTypeParameter
 import org.utbot.framework.plugin.api.util.id
 import org.utbot.framework.plugin.api.util.isArray
+import org.utbot.framework.plugin.api.util.isKotlinFile
 import org.utbot.framework.plugin.api.util.isPrimitive
 import org.utbot.framework.plugin.api.util.isPrimitiveWrapper
 import org.utbot.framework.plugin.api.util.kClass
@@ -72,6 +73,9 @@ internal class CgKotlinRenderer(context: CgRendererContext, printer: CgPrinter =
 
     override val langPackage: String = "kotlin"
 
+    override val ClassId.shouldBeOmittedWhenUsedAsCaller: Boolean
+        get() = isKotlinFile
+
     override fun visit(element: AbstractCgClass<*>) {
         for (annotation in element.annotations) {
             annotation.accept(this)