DRY in the build scripts

Author: dkhalanskyjb

build.gradle

@@ -7,7 +7,6 @@ import org.jetbrains.kotlin.konan.target.HostManager
 import org.jetbrains.dokka.gradle.DokkaTaskPartial
 
 apply plugin: 'jdk-convention'
-apply from: rootProject.file("gradle/opt-in.gradle")
 
 def coreModule = "kotlinx-coroutines-core"
 def testModule = "kotlinx-coroutines-test"
@@ -168,7 +167,7 @@ configure(subprojects.findAll { !sourceless.contains(it.name) }) {
 
     // Configure options for all Kotlin compilation tasks
     tasks.withType(org.jetbrains.kotlin.gradle.tasks.AbstractKotlinCompile).all {
-        kotlinOptions.freeCompilerArgs += optInAnnotations.collect { "-Xopt-in=" + it }
+        kotlinOptions.freeCompilerArgs += OptInPresetKt.optInAnnotations.collect { "-Xopt-in=" + it }
         kotlinOptions.freeCompilerArgs += "-progressive"
         // Disable KT-36770 for RxJava2 integration
         kotlinOptions.freeCompilerArgs += "-XXLanguage:-ProhibitUsingNullableTypeParameterAgainstNotNullAnnotated"

buildSrc/src/main/kotlin/OptInPreset.kt

@@ -0,0 +1,13 @@
+/*
+ * Copyright 2016-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+val optInAnnotations = listOf(
+    "kotlin.RequiresOptIn",
+    "kotlin.experimental.ExperimentalTypeInference",
+    "kotlin.ExperimentalMultiplatform",
+    "kotlinx.coroutines.DelicateCoroutinesApi",
+    "kotlinx.coroutines.ExperimentalCoroutinesApi",
+    "kotlinx.coroutines.ObsoleteCoroutinesApi",
+    "kotlinx.coroutines.InternalCoroutinesApi",
+    "kotlinx.coroutines.FlowPreview")

buildSrc/src/main/kotlin/SourceSets.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2016-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+import org.jetbrains.kotlin.gradle.plugin.*
+
+fun KotlinSourceSet.configureMultiplatform() {
+    val srcDir = if (name.endsWith("Main")) "src" else "test"
+    val platform = name.dropLast(4)
+    kotlin.srcDir("$platform/$srcDir")
+    if (name == "jvmMain") {
+        resources.srcDir("$platform/resources")
+    } else if (name == "jvmTest") {
+        resources.srcDir("$platform/test-resources")
+    }
+    languageSettings {
+        optInAnnotations.forEach { optIn(it) }
+        progressiveMode = true
+    }
+}

gradle/opt-in.gradle

@@ -70,19 +70,8 @@ if (rootProject.ext.native_targets_enabled) {
  * because JMV-only projects depend on core, thus core should always be initialized before configuration.
  */
 kotlin {
-    configure(sourceSets) {
-        def srcDir = name.endsWith('Main') ? 'src' : 'test'
-        def platform = name[0..-5]
-        kotlin.srcDirs = ["$platform/$srcDir"]
-        if (name == "jvmMain") {
-            resources.srcDirs = ["$platform/resources"]
-        } else if (name == "jvmTest") {
-            resources.srcDirs = ["$platform/test-resources"]
-        }
-        languageSettings {
-            progressiveMode = true
-            optInAnnotations.each { optIn(it) }
-        }
+    sourceSets.forEach {
+        SourceSetsKt.configureMultiplatform(it)
     }
 
     configure(targets) {

kotlinx-coroutines-core/build.gradle

@@ -9,17 +9,5 @@ val experimentalAnnotations = listOf(
 )
 
 kotlin {
-    sourceSets.all {
-        val srcDir = if (name.endsWith("Main")) "src" else "test"
-        val platform = name.dropLast(4)
-        kotlin.srcDir("$platform/$srcDir")
-        if (name == "jvmMain") {
-            resources.srcDir("$platform/resources")
-        } else if (name == "jvmTest") {
-            resources.srcDir("$platform/test-resources")
-        }
-        languageSettings {
-            experimentalAnnotations.forEach { optIn(it) }
-        }
-    }
+    sourceSets.all { configureMultiplatform() }
 }