Resolution Facade: Add explicit property for file target platform

compiler/frontend/src/org/jetbrains/kotlin/psi/KtPsiFactory.kt

@@ -32,6 +32,7 @@ import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.ImportPath
+import org.jetbrains.kotlin.resolve.TargetPlatform
 
 @JvmOverloads
 fun KtPsiFactory(project: Project?, markGenerated: Boolean = true): KtPsiFactory = KtPsiFactory(project!!, markGenerated)
@@ -45,6 +46,7 @@ private val DO_NOT_ANALYZE_NOTIFICATION = "This file was created by KtPsiFactory
 var KtFile.doNotAnalyze: String? by UserDataProperty(Key.create("DO_NOT_ANALYZE"))
 var KtFile.analysisContext: PsiElement? by UserDataProperty(Key.create("ANALYSIS_CONTEXT"))
 var PsiFile.moduleInfo: ModuleInfo? by UserDataProperty(Key.create("MODULE_INFO"))
+var KtFile.targetPlatform: TargetPlatform? by UserDataProperty(Key.create("TARGET_PLATFORM"))
 
 /**
  * @param markGenerated This needs to be set to true if the `KtPsiFactory` is going to be used for creating elements that are going

idea/idea-analysis/src/org/jetbrains/kotlin/idea/project/TargetPlatformDetector.java

@@ -38,6 +38,9 @@ public class TargetPlatformDetector {
 
     @NotNull
     public static TargetPlatform getPlatform(@NotNull KtFile file) {
+        TargetPlatform explicitPlatform = KtPsiFactoryKt.getTargetPlatform(file);
+        if (explicitPlatform != null) return explicitPlatform;
+
         if (file instanceof KtCodeFragment) {
             KtFile contextFile = ((KtCodeFragment) file).getContextContainingFile();
             if (contextFile != null) {