Configuration: Use project-level JVM target when facet is absent

#KT-17722 Fixed

idea/idea-analysis/src/org/jetbrains/kotlin/idea/project/Platform.kt

@@ -25,8 +25,10 @@ import com.intellij.openapi.roots.ProjectFileIndex
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.cli.common.arguments.Argument
 import org.jetbrains.kotlin.cli.common.arguments.CommonCompilerArguments
+import org.jetbrains.kotlin.cli.common.arguments.K2JVMCompilerArguments
 import org.jetbrains.kotlin.config.*
 import org.jetbrains.kotlin.idea.caches.resolve.getResolutionFacade
+import org.jetbrains.kotlin.idea.compiler.configuration.Kotlin2JvmCompilerArgumentsHolder
 import org.jetbrains.kotlin.idea.compiler.configuration.KotlinCommonCompilerArgumentsHolder
 import org.jetbrains.kotlin.idea.compiler.configuration.KotlinCompilerSettings
 import org.jetbrains.kotlin.idea.facet.getLibraryLanguageLevel
@@ -113,7 +115,14 @@ val Module.languageVersionSettings: LanguageVersionSettings
     }
 
 val Module.targetPlatform: TargetPlatformKind<*>?
-    get() = KotlinFacetSettingsProvider.getInstance(project).getSettings(this)?.targetPlatformKind
+    get() = KotlinFacetSettingsProvider.getInstance(project).getSettings(this)?.targetPlatformKind ?: project.targetPlatform
+
+val Project.targetPlatform: TargetPlatformKind<*>?
+    get() {
+        val jvmTarget = Kotlin2JvmCompilerArgumentsHolder.getInstance(this).settings.jvmTarget ?: return null
+        val version = JvmTarget.fromString(jvmTarget) ?: return null
+        return TargetPlatformKind.Jvm[version]
+    }
 
 private val Module.implementsCommonModule: Boolean
     get() = targetPlatform != TargetPlatformKind.Common

idea/testData/configuration/projectWithoutFacetWithJvmTarget18/module.iml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <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="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="KotlinJavaRuntime (2)" level="project" />
+  </component>
+</module>

idea/testData/configuration/projectWithoutFacetWithJvmTarget18/projectFile.ipr

@@ -0,0 +1,44 @@
+<?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>
+  <component name="Kotlin2JvmCompilerArguments">
+    <option name="jvmTarget" value="1.8" />
+  </component>
+</project>

idea/tests/org/jetbrains/kotlin/idea/configuration/ConfigureKotlinTest.java

@@ -259,4 +259,8 @@ public class ConfigureKotlinTest extends AbstractConfigureKotlinTest {
     public void testJvm6InProjectJvm8InModule() {
         configureFacetAndCheckJvm(JvmTarget.JVM_1_8);
     }
+
+    public void testProjectWithoutFacetWithJvmTarget18() {
+        assertEquals(TargetPlatformKind.Jvm.Companion.get(JvmTarget.JVM_1_8), PlatformKt.getTargetPlatform(getModule()));
+    }
 }