Native: add .alloc(value) for primitive types to interop runtime

^KT-50312 Fixed

generators/nativeInteropRuntime/NativeInteropRuntimeGenerator.kt

@@ -5,5 +5,51 @@
 
 package org.jetbrains.kotlin.generators.native.interopRuntime
 
-fun main() {
+import java.io.File
+import java.io.FileWriter
+
+fun FileWriter.generateHeader() {
+    appendLine(File("license/COPYRIGHT_HEADER.txt").readText())
+    appendLine("package kotlinx.cinterop")
+    appendLine()
+    appendLine("//")
+    appendLine("// NOTE: THIS FILE IS AUTO-GENERATED by the generators/nativeInteropRuntime/NativeInteropRuntimeGenerator.kt")
+    appendLine("//")
+    appendLine()
+}
+
+enum class PrimitiveInteropType {
+    Boolean, Byte, Short, Int, Long, UByte, UShort, UInt, ULong, Float, Double;
+}
+
+fun FileWriter.generateAllocWithValue(type: PrimitiveInteropType) {
+    val typeName = type.name
+
+    appendLine(
+        """
+        /**
+         * Allocates variable with given value type and initializes it with given value.
+         */
+        @Suppress("FINAL_UPPER_BOUND")
+        public fun <T : $typeName> NativePlacement.alloc(value: T): ${typeName}VarOf<T> =
+                alloc<${typeName}VarOf<T>> { this.value = value }
+    """.trimIndent()
+    )
+}
+
+fun generateUtils(targetDir: File) {
+    FileWriter(targetDir.resolve("_UtilsGenerated.kt")).use { writer ->
+        writer.generateHeader()
+
+        for (type in PrimitiveInteropType.values()) {
+            writer.generateAllocWithValue(type)
+            writer.appendLine()
+        }
+    }
+}
+
+fun main() {
+    val targetDir = File("kotlin-native/Interop/Runtime/src/main/kotlin/kotlinx/cinterop")
+
+    generateUtils(targetDir)
 }