Kotlin Facet: Do not rewrite v2 configuration to latest version

This causes unwanted changes in configuration files
after plugin update

idea/idea-jps-common/src/org/jetbrains/kotlin/config/KotlinFacetSettings.kt

@@ -80,6 +80,7 @@ class KotlinFacetSettings {
         val DEFAULT_VERSION = 0
     }
 
+    var version = CURRENT_VERSION
     var useProjectSettings: Boolean = true
 
     var compilerArguments: CommonCompilerArguments? = null

idea/idea-jps-common/src/org/jetbrains/kotlin/config/facetSerialization.kt

@@ -132,8 +132,8 @@ fun deserializeFacetSettings(element: Element): KotlinFacetSettings {
         1 -> readV1Config(element)
         2 -> readV2Config(element)
         KotlinFacetSettings.CURRENT_VERSION -> readLatestConfig(element)
-        else -> KotlinFacetSettings() // Reset facet configuration if versions don't match
-    }
+        else -> return KotlinFacetSettings() // Reset facet configuration if versions don't match
+    }.apply { this.version = version }
 }
 
 fun CommonCompilerArguments.convertPathsToSystemIndependent() {
@@ -166,10 +166,9 @@ fun CompilerSettings.convertPathsToSystemIndependent() {
     outputDirectoryForJsLibraryFiles = PathUtil.toSystemIndependentName(outputDirectoryForJsLibraryFiles)
 }
 
-fun KotlinFacetSettings.serializeFacetSettings(element: Element) {
+private fun KotlinFacetSettings.writeLatestConfig(element: Element) {
     val filter = SkipDefaultsSerializationFilter()
 
-    element.setAttribute("version", KotlinFacetSettings.CURRENT_VERSION.toString())
     targetPlatformKind?.let {
         element.setAttribute("platform", it.description)
     }
@@ -191,3 +190,35 @@ fun KotlinFacetSettings.serializeFacetSettings(element: Element) {
         }
     }
 }
+
+// Special treatment of v2 may be dropped after transition to IDEA 172
+private fun KotlinFacetSettings.writeV2Config(element: Element) {
+    writeLatestConfig(element)
+    element.getChild("compilerArguments")?.let {
+        it.getOption("coroutinesState")?.detach()
+        val coroutineOption = when (compilerArguments?.coroutinesState) {
+            CommonCompilerArguments.ENABLE -> "coroutinesEnable"
+            CommonCompilerArguments.WARN -> "coroutinesWarn"
+            CommonCompilerArguments.ERROR -> "coroutinesError"
+            else -> null
+        }
+        if (coroutineOption != null) {
+            Element("option").apply {
+                setAttribute("name", coroutineOption)
+                setAttribute("value", "true")
+                it.addContent(this)
+            }
+        }
+    }
+}
+
+fun KotlinFacetSettings.serializeFacetSettings(element: Element) {
+    val versionToWrite = if (version == 2) version else KotlinFacetSettings.CURRENT_VERSION
+    element.setAttribute("version", versionToWrite.toString())
+    if (versionToWrite == 2) {
+        writeV2Config(element)
+    }
+    else {
+        writeLatestConfig(element)
+    }
+}

idea/testData/configuration/loadAndSaveProjectWithV2FacetConfig/module.iml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="FacetManager">
+    <facet type="kotlin-language" name="Kotlin">
+      <configuration version="2" platform="JVM 1.8" useProjectSettings="false">
+        <compilerSettings>
+          <option name="additionalArguments" value="-version -Xallow-kotlin-package -Xskip-metadata-version-check" />
+        </compilerSettings>
+        <compilerArguments>
+          <option name="jvmTarget" value="1.7" />
+          <option name="languageVersion" value="1.1" />
+          <option name="apiVersion" value="1.0" />
+          <option name="coroutinesEnable" value="true" />
+        </compilerArguments>
+      </configuration>
+    </facet>
+  </component>
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="KotlinJavaRuntime (2)" level="project" />
+  </component>
+</module>

idea/testData/configuration/loadAndSaveProjectWithV2FacetConfig/projectFile.ipr

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CompilerConfiguration">
+    <resourceExtensions />
+    <wildcardResourcePatterns>
+      <entry name="!?*.java" />
+      <entry name="!?*.form" />
+      <entry name="!?*.class" />
+      <entry name="!?*.groovy" />
+      <entry name="!?*.scala" />
+      <entry name="!?*.flex" />
+      <entry name="!?*.kt" />
+      <entry name="!?*.clj" />
+      <entry name="!?*.aj" />
+    </wildcardResourcePatterns>
+    <annotationProcessing>
+      <profile default="true" name="Default" enabled="false">
+        <processorPath useClasspath="true" />
+      </profile>
+    </annotationProcessing>
+  </component>
+  <component name="CopyrightManager" default="" />
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/module.iml" filepath="$PROJECT_DIR$/module.iml" />
+    </modules>
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" default="true" assert-keyword="true" jdk-15="true" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+  <component name="libraryTable">
+    <library name="KotlinJavaRuntime (2)">
+      <CLASSES>
+        <root url="jar://$PROJECT_DIR$/../mockRuntime11/kotlin-runtime.jar!/" />
+      </CLASSES>
+      <JAVADOC />
+      <SOURCES>
+      </SOURCES>
+    </library>
+  </component>
+</project>

idea/tests/org/jetbrains/kotlin/idea/configuration/ConfigureKotlinInTempDirTest.kt

@@ -86,4 +86,13 @@ class ConfigureKotlinInTempDirTest : AbstractConfigureKotlinTest() {
         Assert.assertEquals("1.1", settings.apiLevel!!.description)
         Assert.assertEquals("-version -Xallow-kotlin-package -Xskip-metadata-version-check", settings.compilerSettings!!.additionalArguments)
     }
+
+    fun testLoadAndSaveProjectWithV2FacetConfig() {
+        val moduleFileContentBefore = String(module.moduleFile!!.contentsToByteArray())
+        val application = ApplicationManager.getApplication() as ApplicationImpl
+        application.doNotSave(false)
+        application.saveAll()
+        val moduleFileContentAfter = String(module.moduleFile!!.contentsToByteArray())
+        Assert.assertEquals(moduleFileContentBefore, moduleFileContentAfter)
+    }
 }