Refactor "do not check impl" flag for multi-platform projects

Instead of LanguageFeature, make it an AnalysisFlag, which is more clear

compiler/cli/src/org/jetbrains/kotlin/cli/common/CLICompiler.java

@@ -270,9 +270,6 @@ public abstract class CLICompiler<A extends CommonCompilerArguments> {
         if (arguments.multiPlatform) {
             extraLanguageFeatures.put(LanguageFeature.MultiPlatformProjects, LanguageFeature.State.ENABLED);
         }
-        if (arguments.noCheckImpl) {
-            extraLanguageFeatures.put(LanguageFeature.MultiPlatformDoNotCheckImpl, LanguageFeature.State.ENABLED);
-        }
 
         LanguageFeature.State coroutinesState = chooseCoroutinesApplicabilityLevel(configuration, arguments);
         if (coroutinesState != null) {
@@ -282,6 +279,7 @@ public abstract class CLICompiler<A extends CommonCompilerArguments> {
         LanguageVersionSettingsImpl settings =
                 new LanguageVersionSettingsImpl(languageVersion, ApiVersion.createByLanguageVersion(apiVersion), extraLanguageFeatures);
         settings.switchFlag(AnalysisFlags.getSkipMetadataVersionCheck(), arguments.skipMetadataVersionCheck);
+        settings.switchFlag(AnalysisFlags.getMultiPlatformDoNotCheckImpl(), arguments.noCheckImpl);
         CommonConfigurationKeysKt.setLanguageVersionSettings(configuration, settings);
     }
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/HeaderImplDeclarationChecker.kt

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.resolve.checkers
 
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.config.AnalysisFlags
 import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.*
@@ -57,7 +58,7 @@ class HeaderImplDeclarationChecker(val moduleToCheck: ModuleDescriptor? = null)
 
         if (descriptor !is MemberDescriptor) return
 
-        val checkImpl = !languageVersionSettings.supportsFeature(LanguageFeature.MultiPlatformDoNotCheckImpl)
+        val checkImpl = !languageVersionSettings.isFlagEnabled(AnalysisFlags.multiPlatformDoNotCheckImpl)
         if (descriptor.isHeader && declaration.hasModifier(KtTokens.HEADER_KEYWORD)) {
             checkHeaderDeclarationHasImplementation(declaration, descriptor, diagnosticHolder, checkImpl)
         }

compiler/util/src/org/jetbrains/kotlin/config/AnalysisFlags.kt

@@ -39,4 +39,7 @@ private operator fun AnalysisFlag.Companion.provideDelegate(instance: Any?, prop
 object AnalysisFlags {
     @JvmStatic
     val skipMetadataVersionCheck by AnalysisFlag
+
+    @JvmStatic
+    val multiPlatformDoNotCheckImpl by AnalysisFlag
 }

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -52,8 +52,7 @@ enum class LanguageFeature(
 
     Coroutines(KOTLIN_1_1, ApiVersion.KOTLIN_1_1, "https://kotlinlang.org/docs/diagnostics/experimental-coroutines", State.ENABLED_WITH_WARNING),
 
-    MultiPlatformProjects(null, defaultState = State.DISABLED),
-    MultiPlatformDoNotCheckImpl(null, defaultState = State.DISABLED),
+    MultiPlatformProjects(sinceVersion = null, defaultState = State.DISABLED),
 
     ;