Use new -Xinline-classes compiler flag in the corresponding IDEA intention

idea/idea-jvm/src/org/jetbrains/kotlin/cli/common/arguments/CliArgumentStringBuilder.kt

@@ -5,10 +5,20 @@
 
 package org.jetbrains.kotlin.cli.common.arguments
 
+import com.intellij.openapi.util.text.StringUtil.compareVersionNumbers
 import org.jetbrains.kotlin.config.LanguageFeature
 
 object CliArgumentStringBuilder {
-    private const val languagePrefix = "-XXLanguage:"
+    private const val LANGUAGE_FEATURE_FLAG_PREFIX = "-XXLanguage:"
+    private const val LANGUAGE_FEATURE_DEDICATED_FLAG_PREFIX = "-X"
+
+    private val versionRegex = Regex("""^(\d+)\.(\d+)\.(\d+)""")
+
+    private val LanguageFeature.dedicatedFlagInfo
+        get() = when (this) {
+            LanguageFeature.InlineClasses -> Pair("inline-classes", KotlinVersion(1, 3, 50))
+            else -> null
+        }
 
     private val LanguageFeature.State.sign: String
         get() = when (this) {
@@ -18,24 +28,50 @@ object CliArgumentStringBuilder {
             LanguageFeature.State.ENABLED_WITH_ERROR -> "-" // not supported normally
         }
 
-    fun LanguageFeature.buildArgumentString(state: LanguageFeature.State): String {
-        return "$languagePrefix${state.sign}$name"
+    private fun LanguageFeature.getFeatureMentionInCompilerArgsRegex(): Regex {
+        val basePattern = "$LANGUAGE_FEATURE_FLAG_PREFIX(?:-|\\+)$name"
+        val fullPattern =
+            if (dedicatedFlagInfo != null) "(?:$basePattern)|$LANGUAGE_FEATURE_DEDICATED_FLAG_PREFIX${dedicatedFlagInfo!!.first}" else basePattern
+
+        return Regex(fullPattern)
+    }
+
+    fun LanguageFeature.buildArgumentString(state: LanguageFeature.State, kotlinVersion: String?): String {
+        val shouldBeFeatureEnabled = state == LanguageFeature.State.ENABLED || state == LanguageFeature.State.ENABLED_WITH_WARNING
+        val dedicatedFlag = dedicatedFlagInfo?.run {
+            val (xFlag, xFlagSinceVersion) = this
+
+            // TODO: replace to returning xFlag in 1.4 (behaviour for fallback)
+            if (kotlinVersion == null) return@run null
+
+            val isAtLeastSpecifiedVersion = versionRegex.find(kotlinVersion)?.destructured?.let { (major, minor, patch) ->
+                KotlinVersion(major.toInt(), minor.toInt(), patch.toInt()) >= xFlagSinceVersion
+            } == true
+            if (isAtLeastSpecifiedVersion) xFlag else null
+        }
+
+        return if (shouldBeFeatureEnabled && dedicatedFlag != null) {
+            LANGUAGE_FEATURE_DEDICATED_FLAG_PREFIX + dedicatedFlag
+        } else {
+            "$LANGUAGE_FEATURE_FLAG_PREFIX${state.sign}$name"
+        }
     }
 
     fun String.replaceLanguageFeature(
         feature: LanguageFeature,
         state: LanguageFeature.State,
+        kotlinVersion: String?,
         prefix: String = "",
         postfix: String = "",
         separator: String = ", ",
         quoted: Boolean = true
     ): String {
-        val existingFeatureIndex = indexOf(feature.name)
-        val languagePrefixIndex = lastIndexOf(languagePrefix, existingFeatureIndex)
-        val featureArgumentString = feature.buildArgumentString(state)
         val quote = if (quoted) "\"" else ""
-        return if (languagePrefixIndex != -1) {
-            replaceRange(languagePrefixIndex, existingFeatureIndex + feature.name.length, featureArgumentString)
+        val featureArgumentString = feature.buildArgumentString(state, kotlinVersion)
+        val existingFeatureMatchResult = feature.getFeatureMentionInCompilerArgsRegex().find(this)
+
+        return if (existingFeatureMatchResult != null) {
+            replace(existingFeatureMatchResult.value, featureArgumentString)
         } else {
             val splitText = if (postfix.isNotEmpty()) split(postfix) else listOf(this, "")
             if (splitText.size != 2) {

idea/idea-jvm/src/org/jetbrains/kotlin/idea/configuration/KotlinWithLibraryConfigurator.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.config.ApiVersion
 import org.jetbrains.kotlin.config.KotlinFacetSettingsProvider
 import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.config.LanguageVersion
+import org.jetbrains.kotlin.idea.facet.getCleanRuntimeLibraryVersion
 import org.jetbrains.kotlin.idea.facet.getRuntimeLibraryVersion
 import org.jetbrains.kotlin.idea.facet.toApiVersion
 import org.jetbrains.kotlin.idea.framework.ui.CreateLibraryDialogWithModules
@@ -371,7 +372,13 @@ abstract class KotlinWithLibraryConfigurator protected constructor() : KotlinPro
                 facetSettings.apiLevel = feature.sinceVersion
                 facetSettings.languageLevel = feature.sinceVersion
                 facetSettings.compilerSettings?.apply {
-                    additionalArguments = additionalArguments.replaceLanguageFeature(feature, state, separator = " ", quoted = false)
+                    additionalArguments = additionalArguments.replaceLanguageFeature(
+                    feature,
+                    state,
+                    getCleanRuntimeLibraryVersion(module),
+                    separator = " ",
+                    quoted = false
+                )
                 }
             }
         }

idea/idea-jvm/src/org/jetbrains/kotlin/idea/quickfix/ChangeGeneralLanguageFeatureSupportFix.kt

@@ -20,7 +20,9 @@ import org.jetbrains.kotlin.idea.configuration.findApplicableConfigurator
 import org.jetbrains.kotlin.idea.configuration.getBuildSystemType
 import org.jetbrains.kotlin.idea.core.isInTestSourceContentKotlinAware
 import org.jetbrains.kotlin.idea.facet.KotlinFacet
+import org.jetbrains.kotlin.idea.facet.getCleanRuntimeLibraryVersion
 import org.jetbrains.kotlin.idea.roots.invalidateProjectRoots
+import org.jetbrains.kotlin.idea.util.module
 import org.jetbrains.kotlin.psi.KtFile
 
 sealed class ChangeGeneralLanguageFeatureSupportFix(
@@ -56,7 +58,13 @@ sealed class ChangeGeneralLanguageFeatureSupportFix(
                 if (!checkUpdateRuntime(project, feature.sinceApiVersion)) return
             }
             KotlinCompilerSettings.getInstance(project).update {
-                additionalArguments = additionalArguments.replaceLanguageFeature(feature, featureSupport, separator = " ", quoted = false)
+                additionalArguments = additionalArguments.replaceLanguageFeature(
+                    feature,
+                    featureSupport,
+                    file.module?.let { getCleanRuntimeLibraryVersion(it) },
+                    separator = " ",
+                    quoted = false
+                )
             }
             project.invalidateProjectRoots()
         }